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The ecology and harvesting of euphausiids in the Strait of Georgia Heath, William Arthur 1977

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THE ECOLOGY AND HARVESTING OE EUPHAUSIIDS IN THE STRAIT OF GEORGIA  WILLIAM  ARTHUR  B.Sc.(Hons.), U n i v e r s i t y  HEATH  of British  Columbia,  1972  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS  FOR THE DEGREE OF  DOCTOR OF PHILOSOPHY  in  the Faculty  of Graduate  (The Department  Studies  of Zoology  and the I n s t i t u t e  o f Oceanography)  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g required standard  to the  THE UNIVERSITY OF BRITISH COLUMBIA December, 1977 (c)  William  Arthur  Heath,  1977  In  presenting  this  an a d v a n c e d  degree  the  shall  I  Library  f u r t h e r agree  for  scholarly  by h i s of  thesis at  the U n i v e r s i t y  make  that  written  thesis  purposes  for  freely  permission may It  is  The  of  University  British  2075 Wesbrook P l a c e Vancouver, Canada V 6 T 1W5  A p r i l 10, 1978  of  British for  for extensive by  gain  Columbia  shall  the  that  not  reguirements  Columbia,  I  agree  r e f e r e n c e and copying  t h e Head o f  understood  permission.  Zoology  fulfilment of  available  be g r a n t e d  financial  Department o f  Date  it  representatives.  this  in p a r t i a l  of  or  that  study.  this  thesis  my D e p a r t m e n t  copying  for  or  publication  be a l l o w e d w i t h o u t  my  i  ABSTRACT  Populations of Euphausia Georgia  region  which have r e c e n t l y  were s t u d i e d w i t h population  of  euphausiids through  respect  dynamics  management  pacif ica  the  as  in  i n the  history,  order  Strait  been c o m m e r c i a l l y  life  resource.  a food  chemical  to  Hansen  to  The  e  aspects  potential rearing  a n a l y s e s and f e e d i n g t r i a l s  harv sted  distribution  examine  item f o r f i s h  of  use  with  of  of  was a l s o  and the local  evaluated  juvenile  coho  salmon. The for  maximum  life  span i n l o c a l  males and 22 months f o r f e m a l e s .  from  May  to  phytoplankton  September, abundance.  in  t h e f o l l o w i n g year  to  grow  faster  following life  early  phase  to  First-year  and  a similar  (11-12  between  October-November. Inlet  than  is  similar  size-selective  mm) ,  egg  Production  Survival  was  by  Oregon  26.8  ,  mgC/ra /day 2  Growth appeared  mortality  adult 18  a  with stages  mm. maximum  in  P, i n S a a n i c h (P/B  =  8.8),  f o r E._ - p . a c i f i c a .  on f r e e z e - d r i e d  euphausiids  on d i e t s o f e u p h a u s i i d Moist  over  pacifica  J u v e n i l e c o h o s a l m o n a t 9 C showed  3.1%/day  i n summer  increased  (6%/mo) and e a r l y  to  t o t h a t f o r h e r b i v o r o u s copepods, but h i g h e r  a previous estimate  3.8%/day  related  Males  i n each p o p u l a t i o n reached  d u r i n g July-November  which  occurred  maximal  pattern.  (68%/mo) b u t d e c l i n e d s h a r p l y f o r i n d i v i d u a l s T o t a l b i o m a s s , B,  which  closely  g r o w t h was  experienced  maturity  be  19 months  i n autumn and h a l t e d i n w i n t e r .  showed  changes  Spawning,  appeared  (0.094 mm/day) b u t s l o w e d  p o p u l a t i o n s was  Pellet,  meal,  respectively.  mean  compared frozen Local  growth t o 3.0%,  rates  of  2.7%  and  euphausiids euphausiids  and  have a  ii  well-balanced' carotenoid suitable  fish  f o r use  tons  food  during as  early  that  and  of Georgia  the  the  fishery  other  optimal  government  carefully  fisheries  who  need  i n salmon  as  an  about  aguarium  fishery  potential  and  to  further information  value  managers on  have  pacifica  January  plankton  monitored euphausiid  100  aguaculture.  t i m e f o r E±  g u i d e l i n e s on  industry  them  management c o n s i d e r a t i o n s  harvesting  r e g i o n a p p e a r s t o have harvesting  making  harvested  main u s e s a r e  December r a t h e r t h a n f r o m  plankton  dynamics.  euphausiid 1977;  tissue) ,  high  feeds.  a d i e t a r y supplement  between O c t o b e r and s u g g e s t e d by  ya,g/g  (80-219  c a l c u l a t i o n s and  indicated  limited  amino a c i d s i n t h e i r p r o t e i n s and  in aguacultural  Columbia's  and  Yield  as  of  concentrations  British metric  spectrum  to  March  harvesting, i n the to of  zooplankton  is  a  Strait  the  new  associated population  TABLE OF CONTENTS  Page Abstract Table  ..................................................  of Contents  List  of Tables  Lxst  of Figures  i  i i i vi  Acknowledgements  .••..••........,....... . . . . , . . . . . . . . . . . . . . . v i i i . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. ...... ..  x i i  INTRODUCTION CHAPTER  1:  1 BACKGROUND AND METHODS  1«1  X ii^-irocluc "fcion *« • * * « * •«• •«• • •-• • • * • • •  •••*§••••••  1.2  Description  1.3  P r e v i o u s S t u d i e s on E. p a c i f i c a  ..................  6  1.4  M a t e r i a l s a n d Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12  1.41  Sampling P r o c e d u r e s ..............................  13  1.42  Laboratory  14  o f t h e Study Region ..................  P r o c e d u r e s ............................  1.421 L e n g t h Measurements  ..............................  1.422 A n a l y s i s o f L e n g t h - f r e g u e n c y D i s t r i b u t i o n s  .......  1.423 L e n g t h : w e i g h t R e l a t i o n s h i p s 1. 424 I d e n t i f i c a t i o n CHAPTER  2:  of Life  History  •  Q 4  16 17 18  Stages  19  L I F E HISTORY, S I Z E STRUCTURE, GROWTH AND MORTALITY  2.1  Life  2.2  Larval  2.3  Population  .......  28  2.4  P o p u l a t i o n S i z e S t r u c t u r e i n J e r v i s I n l e t and the S t r a i t Of G e o r g i a . . . . . . . . . . . . . . . . . . . . . . . . . . .  37  Mortality of Juvenile  51  2.5  History  Stages  20  Survival Size  27 Structure i n Saanich  and A d u l t  E  A  Inlet  fiacj.fj.ca  iv  2.6  Discussion  CHAPTER 3:  .......................................  BIOMASS AND  61  PRODUCTION  3.1  Length;weight R e l a t i o n s h i p  3.2  Carapace:body Length R e l a t i o n s h i p  3.3  A n n u a l and M o n t h l y E. p a c i f i c a  3.4  P r o d u c t i o n o f E± p_acif i c a  3.5  S p a t i a l D i s t r i b u t i o n s o f Biomass o f M e g a z o o p l a n k t o n and P h y t o p l a n k t o n i n t h e S t r a i t o f G e o r g i a H@cj x o n * • * • * • • * • * • * • • • • • • * • • • • * • * • • * * • * • • • * • * • • * * •  3.6  Discussion  CHAPTER 4:  ,.  76  Biomass  Distribution  ..........  97  EUPHAUSIIDS AS A FOOD  Introduction  4.2  Methods o f C h e m i c a l A n a l y s i s  4.3  Fish  4.31  Methods  110  Feeding T r i a l s  Hss u X  .....................110  with E u p h a u s i i d P r e p a r a t i o n s  . 111  . . . . . v . . ; . , . . . . . , . . . . . . . . . . 111 •  * •«••*• ••••••••*••••••*• • * • • * « • • •  'tis  4.41  C o m p o s i t i o n o f E u p h a u s i i d s .......................  4.42  J u v e n i l e Coho Growth on E u p h a u s i i d P r e p a r a t i o n s  4.5  Discussion  4.51  Composition of Local  4.52  Coho Growth on E u p h a u s i i d  CHAPTER 5:  77 81  .......................................  4.1  #^  74  113  .. 115 118  ZOOPLANKTON  Euphausiids  .................118  Diets  ..119  HARVESTING  5.1  Introduction  .......................  121  5.2  L i t e r a t u r e Review  5.21  Methods o f P l a n k t o n  5.22  Operating Conditions f o r Plankton  5.23  Examples o f P r e s e n t M i c r o n e k t o n a n d Z o o p l a n k t o n H a r v e s t i n g ............. .. 132  ................................ Harvesting  121 125  Harvesting  ..... 128  y  5.231 A n t a r c t i c  Krill,  E u p h a u s i a s u p g r b a . . . . . . . . . . . . . . . 132  5.232 N o r t h A t l a n t i c Copepods and K r i l l , Calanus f i n m a r c h i c u s and MgganYctiphangs n o r v e q i c a 5.233 B r i t i s h C o l u m b i a ' s P l a n k t o n F i s h e r y , and C a l a n u s p l u m c h r n s . . . . . . . . . . . . CHAPTER 6:  Introduction  6.2  Net S e l e c t i v i t y  6.3  Factors  6.4  O t h e r Manaqement C o n s i d e r a t i o n s  CHAPTER 7: *7 # 1  APPENDIX  A  145 CONSIDERATIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155  Affectinq  155 Yield  159 166  SUMMARY  Su m iQctir y  BIBLIOGRAPHY  E, p a c i f i c a  NET S E L E C T I V I T Y , YIELD AND MANAGEMENT  6.1  139  *••••• • •  ........ .  •  «# • • • • « • ••*«:•* * « • * • •  • • . 167  . . . . . . . . . . . . . . . . 170 183  vi  L I S T OF TABLES Table  Page  •1. M o n t h l y mean body l e n g t h s by sex f o r E«_ pacJUEica c o h o r t s i n S a a n i c h I n l e t between J a n u a r y 197 4 ana F e b u a r y 1976. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29  2. Growth c o n s t a n t s f o r von B e r t a l a n f f y e q u a t i o n s f i t t e d t o S a a n i c h I n l e t d a t a on mean body l e n g t h by s e x , p l o t t e d i n F i g u r e 10. . . . . . . . . . . . . . . . . . . . . . . . . .  35  3. Summary o f S a a n i c h I n l e t E . p a c i f i c a growth c o n s t a n t s f o r von B e r t a l a n f f y e q u a t i o n s o f T a b l e 2 a c c o r d i n g t o s e x and s e a s o n . . . . . . . . . . . . . . . . . . . . . . . .  37  4. M o n t h l y mean body l e n g t h s by s e x f o r I pacifica c o h o r t s i n J e r v i s I n l e t between A p r i l and December 1975. . . . . . . . . . . . . . . v . . . . . . . . . . . . . . . . 38 A  5. M o n t h l y mean body l e n g t h s by s e x f o r E . p a c i f i c a c o h o r t s i n t h e S t r a i t o f G e o r g i a between March 1975 and F e b r u a r y 1976 6a.  6b.  40  Growth c o n s t a n t s f o r von B e r t a l a n f f y e q u a t i o n s f i t t e d t o J e r v i s I n l e t d a t a on mean body l e n q t h by s e x , p l o t t e d i n F i g u r e 12. . . . . . . . . . . . . . . . . . . . . . . . . .  45  Growth c o n s t a n t s f o r von B e r t a l a n f f y e q u a t i o n s f i t t e d t o S t r a i t o f G e o r g i a d a t a on mean body l e n g t h by s e x , p l o t t e d i n F i g u r e 14. . . . . . . . . . . . . . . . . . . . . . .  45  7. R e s u l t s o f S t u d e n t ' s t - t e s t s on p a i r e d v a l u e s of von B e r t a l a n f f y c o n s t a n t s f o r s e x e s w i t h i n I i . p a c i f i c a c o h o r t s . ....... .... .. . . .. . . . . .. .. ......  48  8. V a l u e s o f s e l e c t i v i t y , r , f o r p a c i f i c a sexes f r o m S a a n i c h I n l e t f o r p e r i o d s o f no g r o w t h i n 1974 and 1975. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55  9. R e p r e s e n t a t i v e s u r v i v a l r a t e s f o r s t a g e s o f I i £a£ifi£a i n t h e S t r a i t o f G e o r g i a r e g i o n used i n construction of the hypothetical survival c u r v e s i n F i g u r e 19. . . . . . . . . . . . .  59  10a. Summary o f c o n s u m p t i o n o f e u p h a u s i i d e g g s a n d l a r v a e by j u v e n i l e f i s h i n S a a n i c h I n l e t d u r i n g A p r i l - J u l y 1968. ..... . . . . . . . . . . . 10b.  Summary o f p r e d a t i o n by j u v e n i l e f i s h on j u v e n i l e and a d u l t e u p h a u s i i d s i n S a a n i c h I n l e t d u r i n g A p r i l - J u l y 1968.  11. S u r f a c e (0-10m) t e m p e r a t u r e s d u r i n g E. , p a c i f i c a *s main r e p r o d u c t i v e p e r i o d and d u r i n g w i n t e r i n s i x r e g i o n s o f the North P a c i f i c . ....................,.  66  66  72  vii  12.  Summary o f r e s u l t s f o r r e g r e s s i o n o f body l e n g t h on c a r a p a c e l e n g t h f o r E. p a c i f i c a from S a a n i c h I n l e t and t h e S t r a i t o f G e o r g i a . ......................... 77  13.  P r o d u c t i o n e s t i m a t e s and a s s o c i a t e d p a r a m e t e r s f o r E p a c i f i c a p o p u l a t i o n s and c o h o r t s d u r i n g A  June-  14.  P r o d u c t i o n : b i o m a s s r a t i o s and mean l i f e e x p e c t a n c y f o r E. p a e i f i c a p o p u l a t i o n s and S a a n i c h I n l e t c o h o r t s d u r i n g June-November 1975. ,......................... 84  15.  Summary o f o b s e r v a t i o n s on t h e 107 kHz s o u n d s c a t t e r i n g l a y e r and c o r r e s p o n d i n g MNT e s t i m a t e s o f m e g a z o o p l a n k f o n b i o m a s s f o r t h e O c t o b e r 1975 c r u i s e (75/31). . ................................... 90  16a.  Proximate c o m p o s i t i o n o f e u p h a t i s i i d s caught i n S a a n i c h I n l e t , J a n u a r y 1975. . . , ; . . > . . . . . . » . . . . . . 114  16b.  L i p i d and c a r o t e n o i d c o n t e n t o f c o m m e r c i a l c a t c h e s o f e u p h a u s i i d s from S e c h e l t and S a a n i c h I n l e t s . .... 114  17.  amino a c i d c o m p o s i t i o n o f t h r e e p r e p a r a t i o n s o f e u p h a u s i i d s from Saanich I n l e t . , . , . * . . , . . . . . . . . . . . . .  115  18.  C o m p a r i s o n o f i n i t i a l and f i n a l mean v a l u e s f o r »et w e i g h t and f o r k l e n g t h as w e l l a s mean g r o w t h r a t e s o f d i e t g r o u p s i n c o h o f e e d i n g t r i a l s . ....... 116  19.  Summary o f ANO?a on f i n a l wet w e i g h t s , f o r k l e n g t h s , and growth r a t e s o f t h e f o u r c o h o d i e t g r o u p s .  117  20.  C o m p a r i s o n o f means f o r d i e t g r o u p s by S c h e f f e ' s l e a s t s i g n i f i c a n t d i f f e r e n c e { LSD ) method. ....... 118  21.  Summary o f e u p h a u s i i d c a t c h e s by s t a t i s t i c a l a r e a ( F i s h e r i e s S e r v i c e ) and l o c a l i t y f o r 1975-77. ...... 148  22.  Beverton-Holt y i e l d parameters f o r f i r s t - and s e c o n d - y e a r c o h o r t s o f E. p a c i f i c a i n S a a n i c h I n l e t d u r i n g 1975.  23.  List  o f 1975 c r u i s e s ,  w i t h d a t e s and d e s t i n a t i o n s .  160 ... 183  viii  L I S T OF FIGURES Figure  Page  1. The S t r a i t o f G e o r g i a  region  .........................  2. E u p h a u s i i d egg(o) a n d l a r v a l ( t ) a b u n d a n c e s i n S a a n i c h I n l e t d u r i n g J u n e a n d J u l y 1966, f r o m o b l i q u e M i l l e r hauls(12m-0) 3.  21  E u p h a u s i i d e g g ( o ) , l a r v a l (t) and j u v e n i l e (e) a b u n d a n c e s i n S a a n i c h I n l e t from 175m v e r t i c a l h a u l s d u r i n g M a y - J u l y 1968. 22  4. Mean c h l o r o p h y l l - a c o n c e n t r a t i o n i n t h e u p p e r 20 m o f S a a n i c h I n l e t d u r i n g M a y - J u l y 1968. . . . . . . . . 5.  5  C h l o r o p h y l l - a c o n c e n t r a t i o n s i n t h e upper S a a n i c h I n l e t d u r i n g 1975.  23  10 m o f 24  6. F r e q u e n c y o f e u p h a u s i i d l a r v a l t y p e s e n c o u n t e r e d i n M i l l e r n e t s a m p l e s d u r i n g May and June 1975 i n Saanich I n l e t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25  7 . . V e r t i c a l d i s t r i b u t i o n o f temperature (C) a t s t a t i o n Saa-3 d u r i n g 1974-75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26  8. L e n g t h from  frequency d i s t r i b u t i o n s S a a n i c h I n l e t , 1974  30  9. L e n g t h from  frequency d i s t r i b u t i o n s of pacifica S a a n i c h I n l e t , J a n . 1975 t o Feb. 1 9 7 6 . . . . . . . . .  31  ( c o n t i n u e d ) . . . . . . . . . , . . . . . . . . , , . . . . . . . . . •..... .......  32  9. 10.  of |  A  pacifica  Mean modal body l e n g t h s and f i t t e d von B e r t a l a n f f y qrowth c u r v e s f o r f e m a l e ( a ) , male (e) a n d i m m a t u r e ( i ) •E. . p a c i f i c a i n S a a n i c h I n l e t d u r i n q 1974-75. .......  11,. .Length f r e q u e n c y d i s t r i b u t i o n s o f E ^ p a c i f i c a J e r v i s I n l e t , A p r i l t o December 1975 12.  13.  14.  33  from 39  Mean modal body l e n q t h s and f i t t e d von B e r t a l a n f f y growth c u r v e s f o r f e m a l e ( a ) , male (e) and immature ( i ) JU. E a s l f i s a i n J e r v i s I n l e t d u r i n g 1975.  41  Length frequency d i s t r i b u t i o n s o f J pacifica from t h e S t r a i t o f G e o r q i a , March 1975 t o February 1976......................................  43  Mean modal body l e n q t h s and f i t t e d von B e r t a l a n f f y qrowth c u r v e s f o r f e m a l e ( a ) , male (e) and i m m a t u r e ( i ) E. p a c i f i c a i n t h e S t r a i t o f G e o r q i a d u r i n q 197 5. ...,77.................................  46  A  ix  Figure  Page  15. Mean c h l o r o p h y l l - a c o n c e n t r a t i o n s i n t h e u p p e r 10 m o f J e r v i s I n l e t and t h e S t r a i t o f G e o r g i a d u r i n g 1975. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47  16. Changes i n s e x r a t i o (M : F) w i t h body l e n g t h f o r B. p a e i f i c a p o p u l a t i o n s d u r i n g 1 9 7 5 . . . . . . . . . . . .  50  17. C a t c h c u r v e s o f a l l E. p a e i f i c a s a m p l e d d u r i n g 1975 by K i l l e r n e t (HNT) and~by SCOR n e t i n t h e S t r a i t of Georgia region.  52  18.  Examples o f s u r v i v a l c u r v e s f o r J jacifica c o h o r t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...........> ....  57  19. H y p o t h e t i c a l s u r v i v a l c u r v e s f o r E. p a e i f i c a i n t h e S t r a i t o f G e o r g i a r e g i o n . ...................  60  20. R e p r e s e n t a t i v e g r o w t h c u r v e s f o r E. p a e i f i c a from t h e S t r a i t o f G e o r g i a and o t h e r r e g i o n s o f t h e P a c i f i c .  69  21. T o t a l mean b i o m a s s and mean b i o m a s s by 1 mm s i z e c l a s s e s o f E^ p a e i f i c a p o p u l a t i o n s i n t h e S t r a i t o f G e o r g i a r e g i o n d u r i n g 1975................  78  22.  A  Monthly biomass l e v e l s o f c o n s p i c u o u s s i z e of p a e i f i c a d u r i n g 1975  classes 79  23. M o n t h l y c h a n g e s i n b i o m a s s f o r a l l s i z e c l a s s e s (7-23 mm) i n E.. p a e i f i c a p o p u l a t i o n s and i n S a a n i c h I n l e t c o h o r t s d u r i n g 1975. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.  D i s t r i b u t i o n o f wet b i o m a s s (g/m ) o f m e g a z o o p l a n k t o n ( > 5 ram) i n t h e 107 kHz s o u n d s c a t t e r i n g layer d u r i n g M a r c h - A p r i l 1975.  81  3  25. D i s t r i b u t i o n o f wet b i o m a s s (g/m ) o f m e g a z o o p l a n k t o n ( > 5 7m) i n t h e 107 kHz s o u n d s c a t t e r i n g l a y e r d u r i n g J u n e - J u l y 1975. ,  85  3  26.  86  D i s t r i b u t i o n o f wet biomass (g/m ) o f m e g a z o o p l a n k t o n (> 5 mm) i n t h e 107 kHz s o u n d s c a t t e r i n g layer d u r i n g A u g u s t - S e p t e m b e r 1975.  88  27. D i s t r i b u t i o n o f wet b i o m a s s (g/m ) o f m e g a z o o p l a n k t o n (> 5 mm) i n t h e 107 kHz s o u n d s c a t t e r i n g layer d u r i n g October-November 1975. /. . .  89  28. D i s t r i b u t i o n o f m e g a z o o p l a n k t o n b i o m a s s ( g / m ) i n t h e 107 kHz s o u n d s c a t t e r i n g l a y e r i n S a a n i c h I n l e t , J u l y 1975  91  3  3  3  X  29. D i s t r i b u t i o n o f m e g a z o o p l a n k t o n b i o m a s s ( g / m ) i n t h e 107 kHz s o u n d s c a t t e r i n g l a y e r i n S a a n i c h I n l e t , August 1975. , .. ...................... 9 3 3  30. Change i n mean p e r c e n t a g e o f t o t a l m e g a z o o p l a n k t o n b i o m a s s c o n t r i b u t e d by E. p a c i f i c a d u r i n g 1975 . . . .  94  31. D i s t r i b u t i o n o f c h l o r o p h y l l - a (mg/m ) i n t h e u p p e r 10 m i n t h e S t r a i t o f G e o r g i a r e g i o n , J u n e - J u l y 1975. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  95  3  32.  D i s t r i b u t i o n o f c h l o r o p h y l l - a (mg/m ) i n t h e u p p e r 10 m, A u g u s t - S e p t e m b e r 1 9 7 5 . . . . . . . . . . . . . . . . . . , 96 3  33. D i s t r i b u t i o n o f c h l o r o p h y l l - a {mg/m ) i n t h e upper 10 m, October-November 1975. . . . . . . . . . . . . . . . . . 3  34.  F r e g u e n c y d i s t r i b u t i o n s o f wet w e i g h t f o r j u v e n i l e coho s a m p l e d b e f o r e and a f t e r f e e d i n g t r i a l s on f o u r d i e t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,  98  116  35..The e f f e c t o f f i s h i n g e x p e r i e n c e on e u p h a u s i i d f i s h i n g s u c c e s s , CPE i n S t r a i t o f G e o r g i a w a t e r s d u r i n g t h e 1976 and 1977 s e a s o n s . . . . . . . . . . . . . . . . . . . 149 36. C o m p a r i s o n o f s i z e c o m p o s t i o n o f e u p h a u s i i d c a t c h f r o m SCOH, MNT and IKMT h a n l s i n S a a n i c h I n l e t , A u g u s t 1975. 157 37. C o m p a r i s o n o f s i z e c o m p o s i t i o n o f e u p h a u s i i d c a t c h f r o m SCOB and IKMT h a u l s i n S a a n i c h I n l e t , March 1975. .. 158 38. C o m p a r i s o n o f s i z e c o m p o s i t i o n o f e u p h a u s i i d c a t c h i n s a m p l e s f r o m M i l l e r n e t (MNT) and c o m m e r c i a l p l a n k t o n n e t tows t a k e n c o n s e c u t i v e l y i n S a a n i c h I n l e t , J a n u a r y 1977. .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 39. C o n t o u r s o f e g u i l i b r i u m y i e l d / r e c r u i t f o r t h e s p r i n g 75 c o h o r t o f E . -.-pacificai n a f i s h e r y commencing a t t i m e t a n d e n d i n g a t t i m e t=11 m o . ( A p r i l ) . . . . . . . . . . . . . . . . . . . . .  161  40. C o n t o u r s o f e g u i l i b r i u m y i e l d / r e c r u i t f o r t h e s p r i n g 74 c o h o r t o f E p a c i f i c a i n a f i s h e r y commmencing a t t i m e t and e n d i n g a t t i m e t=22 mo. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  162  A l  41.  R e l a t i o n s h i p s between y i e l d / r e c r u i t and f i s h i n g m o r t a l i t y f o r 3-month f i s h e r i e s b e g i n n i n g i n O c t o b e r a n d J a n u a r y . . . . . . . . . . . . . . . . . . . . 164  xi  42.  Cruise t r a c k s f o r survey 75/12 ( A p r i l ) .  c r u i s e s 75/10  (March) and 184  43.  C r u i s e t r a c k s f o r s u r v e y c r u i s e s 75/21 ( J u n e ) , 75/24 ( J u l y ) and 75/25 ( J u l y ) . . . . . . . . . . . . . . . . . . . . . . 185  44.  C r u i s e t r a c k s f o r s u r v e y c r u i s e s 75/27 (August) and 75/29 ( S e p t e m b e r ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  186  C r u i s e t r a c k s f o r s u r v e y c r u i s e s 75/31 and 75/33 (November)  187  45.  (October)  xii  ACKNOWLEDGMENTS This  p r o j e c t would n o t h a v e been p o s s i b l e w i t h o u t  of  many  people.  for  his suggestions,  am  grateful  and  to  a d v i c e and s u p p o r t  assisted  II, I  services.  of  C.S.S.  Oceanography  extend  Vector,  completing  who  C.N.A.7.  bridge  fishermen  in  shared  I  and  the  logs. In a similar  R.V.  c o - o p e r a t i o n and  for their  answering  ship  and crew o f t h e  Laymore  my g r a t i t u d e f o r t h e i r  I a l s o thank t h e p l a n k t o n  the study.  s t u d e n t s , f a c u l t y and  i n my work. To t h e o f f i c e r s  i n t h e p r o j e c t and c o - o p e r a t i o n and/or  throughout  t h e many f e l l o w g r a d u a t e  research vessels, Pandora  help  I t h a n k ray t h e s i s s u p e r v i s o r . D r . T.H. P a r s o n s  technicians at the I n s t i t u t e time  the  interest  guestionaire  way, I am  grateful  t o t h e h a r v e s t i n g c o m p a n i e s f o r i n f o r m a t i o n on l a n d e d  catch  access  I t h a n k my  to  commercial samples  wife, V a l e r i e , typing  much  f o r h e r generous h e l p of  the  manuscript.  committee  members, D r s .  for  advice  their  thank fishery  biologist  the  and  drafting  figures  a n d f o r making  a post-graduate support  Council  and  I am g r a t e f u l t o my r e s e a r c h Northcote,  O s b o r n and  f o r improving  Walters  t h e manuscript.  f o r i n t r o d u c i n g me t o t h e v i e w p o i n t  Besearch  for research  6689.  i n  analyses.  a  computer  H o l t model a v a i l a b l e t o me. F i n a l l y ,  National  through  Carefoot,  and s u g g e s t i o n s  Dr. Wilimovsky  Beverton-  f o r chemical  and  of  Canada  program  I  ofthe of the  I am g r a t e f u l t o  f o r supporting  me  bursary  and s c h o l a r s h i p d u r i n g my work,  through  my s u p e r v i s o r ' s g r a n t  NBC  67-  1  INTRODUCTION The  Strait  productive et  of  Georgia  commerical  fish,  groundfish  local the  (Johnson,  inlets.  as  Pacific  life  history  populations  of  inlets  maintain  zooplankton  (Parsons  number  in  a commercial  goals  the  of  ecology  this  zooplankton  l o c a l waters, subregions the  affecting t h e use  the  to estimate Strait  the  Consequently, been  pacifica  and  on  the  potential  yield.  An  as a f o o d  and  the  animal  auxiliary  and  phytoplankton  and  f o r salmon  the  distribution history i n  pacifica  i n three  to  describe  t o examine is  to  factors evaluate  rearing.  i n f o r m a t i o n on  the  study  ; a description  a n a l y s i n g samples  of  of  zooplankton  follows. presents  r e s u l t s and  basic  population biology of I i , p a c i f i c a  Inlet  and  the  the  aim  s u b j e c t , E._ p a c i f i c a  methods f o r c o l l e c t i n g  2  and  above  Hansen,  secondly  fishery  1 p r o v i d e s seme b a c k g r o u n d  hampered.  the l i f e  p r o d u c t i o n of I i  of  the  Chapter  to i n t e r p r e t  development  the  a r e t o examine the  Enphausia  of Georgia;  has  p o p u l a t i o n dynamics o f  study  resource,  of e u p h a u s i i d s  Chapter area  and  of the  recent  fishery  on  marine r e s o u r c e has  of  various  available  waters.  this  of  g r o u p , the e u p h a u s i i d s , i n  and  B.C.  stocks  h e r r i n g , salmon and  dominant e u p h a u s i i d s p e c i e s , i n o r d e r t o a s s e s s of  of  L i m i t e d g u a n t i t a t i v e d a t a h a v e been  main  aspects  and a  1976). R e c e n t l y ,  management o f t h i s  The  support  a major z o o p l a n k t o n  distribution,  euphausiid  turn  such  to exploit  rational  i t s adjacent  populations of phyfoplankton  a l ^ ,1970) which i n  begun  and  Strait  of G e o r g i a ;  discussion concerning i n Saanich  r e s u l t s of  the  the  Inlet,  Jervis  present  study  2 are  discussed i n relation  o t h e r r e g i o n s of the relation  to  work  parts of the  world  Chapter biomass  in  the  North on  subregions  the a n a l y s i s through  of  estimates of  for  1975  are  of  in  of  the S t r a i t  • E. . p a e i f i c a  G e o r g i a a r e compared  zooplankton.  In  of  to  length:weight  p r o d u c t i o n by  4 examines t h e q u a l i t i e s  potential  aquacultural  source  feeds.  An  of  addition,  Georgia  with the  phytoplankton region  during  three different Chapter  5  experiment  and  pigmentation  i s d e s c r i b e d which  looks  at  the r e l a t i v e l y  new  h a r v e s t i n q . A review  the  in  world  euphausiids  in  British  fisheries. Columbia  The waters  local  fed  diet.  research into  t o summarize t h e p r e s e n t s t a t u s o f t h i s  development  compares  a control  of  make for  j u v e n i l e c h o h o which a r e  p r e p a r a t i o n s o f e u p h a u s i i d s and  of z o o p l a n k t o n  presented  o f e u p h a u s i i d s which  protein  qrowth r a t e s o f f o u r q r o u p s o f  prospects  in  presented.  Chapter  is  application  mortality  b i o m a s s f o r m e g a z o o p l a n k t o n and  survey c r u i s e s over  the  possible,  o f growth and  the S t r a i t  from  a  where  paeifica  s p e c i e s of e u p h a u s i i d s i n v a r i o u s  Estimates of secondary  distributions  them  and  E.  ocean.  distributions  previous  Pacific,  other  3 extends  relationships.  t o p r e v i o u s s t u d i e s on  the  literature important  fishery  i s described in  for this  context. Chapter the  fishery,  6 examines f a c t o r s such  as  net  w h i c h miqht a f f e c t  selectivity,  distribution of harvestinq effort.  The  the  yield  to  t i m e o f h a r v e s t i n q and  f i n d i n q s are discussed i n  3 relation  to  zooplankton Chapter  the  recently  stated  guidelines  on  harvesting. 7  presents  a  summary  s u g g e s t i o n s f o r f u r t h e r r e s e a r c h on zooplankton  government  harvesting.  of  the  euphausiid  study  and  ecology  offers and  on  4 CHAPTER 1.1  1: BACKGROUND AND METHODS  Introduction As  a  principal  contribution important  aim  of this  s t u d y i s t o make a  t o o u r knowledge o f t h e p o p u l a t i o n  zooplankton  and of  oceanography  1.2 D e s c r i p t i o n  o f t h e Study  Strait  of Georgia  and  t h e mainland  km  l o n g , with an average  156  m. A s s o c i a t e d w i t h  several Island,  coast.  with t h e P a c i f i c  that  significantly  have  The  . paeifica•. .  { F i g u r e 1 ) , between V a n c o u v e r  the  main  such  channel  as  limit  waters  Saanich  of the S t r a i t  the S t r a i t  described  Strait  shallow the  by  of  the  Inlet  Howe Sound and J e r v i s  o f Juan  to the  transport  and t h e P a c i f i c  and  Pickard(1961)  features of  on t h e  several  mainland  exchange to the  There  Saanich  i s Inlet  euphausiid  Ocean.  by  while  Inlet  of  o f Saanich I n l e t  Herlinveaux(1962)  are  Vancouver  features of the S t r a i t  W a l d i c h u c k (1 957)  depth o f  de Fuca  to  200  on  north.  D o d i m e a d ( 1 9 5 7 ) . The o c e a n o g r a p h y  oceanographic  Island  strait  of Georgia  approaches  inward  general oceanographic  been  ±  Ocean t h r o u g h t h e S t r a i t  the  p o p u l a t i o n s from The  geography  Region.  and t h r o u g h J o h n s t o n e  evidence  physical  w i d t h o f 30 km and an a v e r a g e  and B u r r a r d I n l e t ,  southwest  an  i ti s useful to  o f Canada a n d t h e U n i t e d S t a t e s , i s a b o u t  fjords(inlets),  mainland  the  of  o f t h e s t u d y r e g i o n , and t o summarize t h e s c o p e  p r e v i o u s s t u d i e s on t h e b i o l o g y o f E  The  biology  s p e c i e s i n l o c a l waters,  b e g i n w i t h a r e v i e w o f some a s p e c t s o f  practical  by  of Georgia Tully  was  and  reviewed  has  described  inlets,  including  5  FIGURE 1. The  Jervis  Inlet.  Strait  of Georgia  Lazier<1963)  region.  discussed  p h y s i c a l processes  i n the  6 J e r v i s and The Strait  Sechelt Inlet  major i n f l u e n c e s on of  tides,  Georgia  freshwater  biological the  and  light  the  water  adjacent  freshwater  The  Georgia  community  and  production  paeifica  the  North  along  1949;  Drift  processes  common  California)  of to  temperate  part  of the  N  Strait  radiation of  Strait  of  Parsons  North  Pacific  zooplankton 40  and  50  of  N;  extends  Georgia  raschii  x  T._,  and  species  community  most a b u n d a n t e u p h a u s i i d ,  inermis  and  ,1969).  of  i t s range  from  25  N  (Banner,  region, while  E±  other  spinifera^  f r e q u e n t l y o c c u r r i n g species are  Thysanoessa  with  activity  the by  of  salinity  (northern G u l f of Alaska)  the  stress,  cycle  solar  of  America  i n c l u d e Thysanoessa  longipeSi Less  dif f icilisj,  a  North  60  In  i s u s u a l l y the  species  is  et alv  the  associated  photosynthetic  between l a t i t u d e s  coast  Brinton,1962).  paeifica  Tj_  west  i s closely  have been d e s c r i b e d  important  Pacific  the  (southern  an  annual  run-off(affecting  co-workers(1969a,b;1970; LeBrasseur  which makes up  The  of  a r e wind  i n t h e s u r f a c e w a t e r s ) and  phytoplankton).  Euphausia  oceanography  inlets  sunlight.  temperature  plankton  physical  of the s t r a i t  changes i n  extinction  (affecting  the  r u n - o f f and  production  seasonal  and  systems.  and  Nematoscelis  T e s s a r a b r ach i o n  oculatus  ( F u l t o n , 1 968) .  1.3  Previous  Aspects observed and  in  of the l i f e a  Pacific,  Paeifica  history  o f Euphausia  number o f o c e a n i c  Ponomareva(1963)  western  E.  s t u d i e s on  by  in  the  Smiles  environments;  north and  paeifica  temperate Pearcy(1971)  by  have  Nemoto(1957)  region in  been  the  of  the  Oregon  7 offshore  and  California two  inshore  Current  zones,  and  o f f southern  p o p u l a t i o n s o f E._  pacifica  by  California.  physiology  several  of  researchers.  1960;1964;1966; have  respiration,  moulting  ship  off  and et  and  the carbon  estimated  energy  pressure  on  crustaceans  (Small  Childress,1971).  and  G i l f i l l a n {1972)  compared oceanic,  waters  experimental  from  (Saanich  combinations  other  1970  by  1962;  zooplankton  Bary  and  co-workers  brief  below. The  s k e t c h o f the  the  and  from  Saanich I n l e t  of  E._  under  euphausiids  were p e r f o r m e d  Pieper,1970;  b i o l o g y o f E.  relevance of several  of  the  Inlet,  pacifica and  from  various  salinity.  between  ( B a r y , B a r r a c l o u g b and and  S m a l l , 1968;  respiration.  B.C. and  of  migrating  Saanich  and  of  (Small  effect  oceanic-coastal  Inlet)  B a r y , 1 9 6 6 a ; 1 9 6 6 b ; Bary A  i n the l a b o r a t o r y  respiration  mixed  fish)  board  c o l l e a g u e s measured  Pearcy  of temperature  and  on  vertically  moulting  a c o u s t i c s t u d i e s of the as  these  the  and  growth,  p o p u l a t i o n s o f f Oregon  specimens  studied  coastal  and  Hebard,1967;  P a r a n j a p e (1967)  specimens from  Small  in  With  Jerde  budget of specimens i n the  They a l s o c o n s i d e r e d  respiration  by  (Lasker,  feeding,  a t v a r i o u s temperatures  a l . . ,1966; S m a l l , 1 9 6 7 ) .  Washington).  been i n v e s t i g a t e d  of  of  determined  of specimens observed  flow of f i e l d  the  cycles  co-workers  aspects  California.  respiration  were  Theilacker,1965;  as w e l l a s m o u l t i n g southern  euphausiid  and  and  described  has  in  life  University of  pacifica  Lasker  Lasker  Lasker,1966)  laboratory,  JEj_  The  i n P u g e t Sound  by H u l s i z e r ( u n p u b l i s h e d m a n u s c r i p t , The  Brinton(1976)  1961  well and  Herlinveaux,  Pieper,1971).  pacifica  above  (as  i s presented  papers  will  be  8  described Ii  i n more d e t a i l  £acifica  m o u t h p a r t s and  is  i n subsequent  an  thoracic  omnivorous f i l t e r appendages  (Mauchline  and  s p e c i e s has  been c o n s i d e r e d t o be  zooplankters  Fisher,  themselves nauplii. could  on  waters  a  mainly  rations  particles  as  on  that  region,  (personal  for  E.. p a c i f i c a  in  microzooplankton  may  coastal be  latitude just  life and  history  of  environmental  l e s s than  and  E.  a t n i g h t i n the  Strait  It  appears  regions,  during the  pacifica  shows  the l i f e  variations span  from  (Smiles  and  about  years i n the s u b a r c t i c r e g i o n o f the northwest 1957;  correspondingly higher  southern C a l i f o r n i a ( B r i n t o n ,  Ponomareva, h i g h e r i n the  latitudes.  1963). southern  Growth  with  ranges  1971)  (Nemoto,  in  1970).  Pearcey, two  off  whereas  w i n t e r and  a y e a r i n t h e p o p u l a t i o n s o f f Oregon and  that  i s a major source of food  LeBrasseur,  conditions;  were e a t e n .  taken  upwelling  more i m p o r t a n t  o c e a n i c environments (Parsons  The  and  from  specimens  observation).  d u r i n g most o f t h e y e a r , p h y t o p l a n k t o n  crustacean  during  scatterinq  Georqia  maintain  observed  from of  that  of diatoms  o f t e n be  layer  smaller  B... p a c i f i c a  i n diameter  guts of f r e s h l y cauqht  s h a l l o w sound  this  found  can live  suspensions  c e l l s can  of  adult  March t o December i n t h e the  apparatus  has  California  as s m a l l as 5u.m  G r e e n masses o f p h y t o p l a n k t o n  filterinq  a predator  well  on  f e e d e r which u s e s i t  Lasker{1966)  southern as  sections.  oceanic environments,  e t a l * . (1967) o b s e r v e d  maximal  Inlet;  off  as  In  1963).  phytoplankton  Parsons  obtain  Saanich  1969).  (Ponomareva,  i n d i v i d u a l s from  discussion  1976)  to  Pacific  rates  upwelling r e g i o n s than  are at  9 Populations extensive l i  £acifica  while  Bary  offshore  vertical  are  regions  migrations;  sampled  of v e r t i c a l and c o w o r k e r s  Racifica  from  presence Inlet  migrating  d e p t h s below 200m  (e.g. Bary  and  t h e day d e p t h o f t h e  sound to  constitute  a  intervals.,  The  of  the  the  population  physiological Inlet  a t n i g h t . The  and  most  other  of  were  high  directly  i n t h e l a y e r i n most  population  area,  has o b v i o u s  of  population  and from P a c i f i c  support  a  at least  i s likely  the  populations  at  parameters are than  newly  an open  area  Inlet  t o be d i s t i n c t differences from  as  that,  Saanich  taken  to  arrived  contention  example,  between J V p a c i f i c a  sampled  sea r e g i o n such  the  region,  organisms  rather  by  Georgia  Ocean  be  advantages over  populations..For  responses  can  a semi-enclosed  of  i f the i n d i v i d u a l s  i n population  former  o f evidence  Strait  oceanic  changes  which  the  o f E.. p a c i f i c a  neighbouring  that  100m i n S a a n i c h  layer  interpreted  within  o f Georgia  sea. Several l i n e s  within  The  found  measurements  the  population  observed  &s a s t u d y  Strait  1970)  b i o l o g y of a group  readily  distinct  of  assemblage. the  most  due t o p r o c e s s e s  replacement  50m.  ( P i e p e r , 1971) .  S t u d i e s on t h e p o p u l a t i o n be  adult  i n c o a s t a l waters;  euphausiids  t h e d r y biomass o f e u p h a u s i i d s  clearly  upper  below about  by  most  sound s c a t t e r i n g l a y e r a t  Quantitative  backscattering  months o f t h e y e a r  then  i n the  Pieper,  waters  undergo  ( B r i n t o n , 1962)  t h e day b u t a s c e n d s t o t h e u p p e r 30m  zooplankton.  freguency  daytime  c a n be much l e s s  of oxygen-deficient  limits  related  migration  the P a c i f i c  in  g e n e r a l l y forms a d i s t i n c t  55-90m d u r i n g  can  of  a t n i g h t most s p e c i m e n s a r e t a k e n  range  Ii  diel  in  from in  Saanich  have i n d i c a t e d t h a t t h e  10 Saanich  Inlet  population  environmental conditions by o c e a n i c p o p u l a t i o n s . that  specimens  sensitive from  and  to  developed  are d i s t i n c t  E. . - p a e i f i c a  from  region.  lighting  brighter  experienced  at  (below  population.  The  of  depth  in  about  from  to  preferred  Inlet  found  a r e more indiviuals  Saanich  which  Inlet  i s greener i n  intensity 250m) by  mechanism o f a d a p t a t i o n was  more  those  Saanich  E._ p a e i f i c a  significantly  storing  from  than to blue i n c o n t r a s t t o  environmental  day  tolerances  For example, Boden and Kampa(1965)  Diego Trough  adapted  colour  which  t o green l i g h t  the San  have  of  has  than  the  thought  that  California to  a s t a x a n t h i n i n the e y e s t o a c t a s a  be  the  screening  pigment.  Respiratory environmental are  well  stress;  adapted  have h i g h e r r a t e s by  the  same  specimens higher Juan  of r e s p i r a t i o n  E. ..-paeifica  Strait  to  from  indicate  s e t of c o n d i t i o n s  than t h o s e which Gilfillan, Saanich  Inlet  (mixed o c e a n i c - c o a s t a l  salinities  waters below  specimens  between 34 and  The  was  24 %o  were  27%o,  and  water)  (oceanic  the  5 to  from  from  the  water).  The  from  reduced at  reduced s i g n i f i c a n t l y  above d i f f e r e n c e s i n  that  tolerate  and  respiration  from  found  than i n d i v i d u a l s  significantly  temperatures  which  stressed  could  from o c e a n i c and  whereas t h e  not  He  to  generally  are  1972).  and l o w e r s a l i n i t i e s  r a t e s of the i n d i v i d u a l s  oceanic-coastal  response  of a zooplankton species  west o f t h e Queen C h a r l o t t e I s l a n d s  respiratory  Inlet  used  a particular  c o n d i t i o n s (e.g.  of  de F u c a  be  individuals  to  temperatures  Pacific  for  r a t e s can  of  mixed  15 C  and  Saanich  for salinities  15 C i n summer.  physiological  reactions  of  11 JLL  paeifica  individuals  regions suggest that  from  Saanich I n l e t  there i s r e l a t i v e l y l i t t l e  t h e s e p o p u l a t i o n s o f E.. p a e i f i c a Saanich  Inlet  plausible  i t s approaches  elements  paeifica  exchange  to  the  because  has  a  oceanographic features  (Herlinveaux,  Saanich  relatively  Inlet  than from  u s u a l i n most B r i t i s h C o l u m b i a a  weak  1962)  tidally  where t h e w a t e r at  the  compensating necessary sill  of  Pacific  population  of  t h e head  of t h e i n l e t as i s  inlets(Pickard,  assisted  surface  1961).  outflow  from the Haro  (75m)  on  the  lower Strait dense  1962). A  o f w a t e r , t o p r o v i d e t h e s e a water the waters  above  i n t h e i n l e t . T h i s weak e s t u a r i n e  effect  is,  more  same d e p t h i n S a a n i c h I n l e t ( H e r l i n v e a u x ,  f o r entrainment, tends to flush  has l i t t l e  There  a t a given s u b s u r f a c e depth i s always  subsurface inflow  depth  flushing  enters the i n l e t  reaches of the i n l e t through S a t e l l i t e Channel i n t o  than  of  provide a  estuarine  most o f t h e f r e s h w a t e r r u n - o f f  from t h e a p p r o a c h e s r a t h e r  however,  between  .  Saanich I n l e t action  . The  more o c e a n i c  mechanism f o r t h e r e s t r i c t i o n o f a d m i x i n g  population Ii  and  and f r o m  the  deep  the  circulation  waters  in  basin  i n Haro  S t r a i t above the s i l l  (234m  maximum) .  Only  when  become more d e n s e will  significant  Inlet  basin;  other  the  waters  than the waters intrusion  this inflow  zooplankters  from  might  of  bring  outside  e u p h a u s i i d s outwards  water.  an  event  could  the s i l l  seawater  Saanich I n l e t Such  below  i t  waters  and  occur  the  inlet  occur i n the Saanich  with  with the  in  depth  euphausiids  and  might  transport  displaced  resident  several  times  in  rapid  12 succession occurence In  o r not at a l l f o r s e v e r a l of sufficiently  order  for  waters t o occur, present  the  This  t h e i m m i g r a n t s would  distribution  usually  I»_ p a c i f i c a  of  pacifica  outflow  at  occasionally  are  as  caught  small  in Satellite  and i t s a p p r o a c h e s  summary,  will  i t seems l i k e l y  a distinct  breeding  Saanich  of  Channel.  with  populations i n adjacent  outside Inlet  with t h e s u r f a c e !•. p a c i f i c a  are  Further evidence samples from  presented  p o p u l a t i o n with  significant  Some  in  that the euphausiids  form  between  from  o f plankton  be  vertically  the i n l e t  numbers  o b s e r v a t i o n s on t h e c o m p o s i t i o n Inlet  from  be  during the  elements  probability.  swept  outside  have t o  Conseguently  population  low  likely  night  from  likely  the  occurs only f o r a short  migrate  s u r f a c e and d e e p e r d a y t i m e d e p t h s .  on  Strait.  a b o u t 60 t o 80m i n Haro S t r a i t  waters has a r e l a t i v e l y l i  input of euphausiids  t w i c e a day when t h e e u p h a u s i i d s  immigration  depending  dense o u t s i d e water i n Haro  large  though,  a t depths from  intrusion. time  a  years,  only  from  Saanich  Chapter  3.  i n Saanich limited  In  Inlet  exchange  waters.  1.4 M a t e r i a l s and Methods In o  f  76, 1975 of  Ii  order to follow the l i f e pacifica  including  Georgia.  giving  , a t o t a l o f 26 c r u i s e s were t a k e n  10 i n S a a n i c h  t o Saanich  h i s t o r y and p o p u l a t i o n d y n a m i c s  Inlet,  appendix  the cruise  Inlet  Jervis Inlet, A  contains  numbers, d a t e s  c h a r t s with t h e survey  during  cruise  and  tracks  1974,  d u r i n g 1974-  and  15  during  Knight  Inlet  and t h e S t r a i t  a list  o f t h e 1975 c r u i s e s ,  destinations indicated.  as  well  as  13 1.41  Sampling The  field  horizontal during  Procedures. sampling  distribution  the  survey  and  the  cruises.  To  euphausiids, sampling as  possible;  dark  procedures  Nitex  netting  generally  at  (HP  from  Inlet  were from  60 m/min and r a i s e d  after  dark  diameter, towed layer  depth  by  6  depths  was  8  net  knots  avoidance  o f darkness  for  diameter  Hauls  in  and  of  section  0. 350  mm  Inlet  were  Georgia  and  t o t h e s u r f a c e . The n e t was  of with  the  euphausiids  standard  lowered  Miller,1961). (3 o r 4 m/sec)  was  Miller These  from  nets(11.3 samplers  cm  were  than  method.  echosounders. 25 m;  Volume  sampling of  water  t h e d i s t a n c e towed and t h e a r e a o f  100% f i l t e r i n g SCOB  sampled  i n the s o u n d s c a t t e r i n g  net  (HP  efficiency -2,  f o r the M i l l e r  1968).  harvesting  midwater  was  done  Clogging  with a modified  by  mesh and 5 mm  6-foot  t r a w l ( IKMT ) . T h i s n e t ( I s a a c s and K i d d ,  Banse and Semon, 1963) h a s an e f f e c t i v e The  much  was r a r e .  Experimental Isaacs-Kidd  as  ( C l u t t e r and  Saanich  in the Strait  by t h e w i r e a n g l e  the  by t h e  s a m p l e s were c o l l e c t e d by  a t n i g h t were g e n e r a l l y l e s s  n e t mouth, a s s u m i n g  euphausiids  a t 30 m/min.  estimated  phytoplankton  2  200m  Nitex;  was e s t i m a t e d  n e t and 94%  m.  1968) .  transects  or  of  a s r e c o r d e d by 107 and 200 khz B o s s F i n e l i n e  filtered  1953;  zooplankton  distribution  0.350 mm  at  Sampling  the  -2,  t o sample t h e  m a t e r i a l s were a l s o u s e d  150-0m w h i l e t h o s e  Horizontal  stages  reduce  h a u l w i t h a . SCOP, n e t o f 57 era  netting  Jervis  life  was done i n t h e h o u r s  A n r a k u , 1968) . Most d a y t i m e vertical  were a d o p t e d  mouth  area of  a p e r t u r e s were c h a n g e d t o 8 mm f o r t h e f r o n t f o r the remainder  o f t h e net and codend.  A  2.9 3 m 45  14 cm  nylon zipper  the catch. m/sec)  a t t h e end o f t h e codend  The IKMT was towed  at  depths  estimated  l a y e r . The TKMT c a t c h material  f o r length  preserved  i n neutral  placed  in plastic  during to  subsampled  frequency  analysis.  5% f o r m a l i n . and  darkness  at  removal o f  2  knots  (1  be w i t h i n t h e s o u n d s c a t t e r i n g  was r a n d o m l y  bags  facilitated  f o r about Each  25 g  subsample  of was  The r e m a i n d e r o f t h e c a t c h was  frozen  f o r use  in  fish  rearing  e x p e r i m e n t s and f o r c h e m i c a l a n a l y s e s , Water s a m p l e s in  7-litre  2,  5,  Van Dorn  and  often  were f r e g u e n t l y according  Vertical  (XBT),  and 5 - l i t r e  during  taken, e s p e c i a l l y  collected  b o t t l e s f r o m d e p t h s o f 0,  samples from g r e a t e r  i n Saanich Inlet.  and P a r s o n s ( 1 9 7 2 )  by  depths  A n a l y s i s was  spectrophotometry  methods. temperature 1974 and  by i n s i t u  profiles  1975  by  and b u i l t  in  saanich  expendable  and  depth  Inlet  were  bathythermograph  s a l i n o m e t e r (Beckman p o r t a b l e ,  a thermistor-equipped temperature desiqned  measurements were  Niskin  10 m. A d d i t i o n a l  to Strickland  or f l u o r o m e t r i c  measured  for chlorophyll-a  RS5-2),  probe  and by  which  was  a t DBC.  1.42 L a b o r a t o r y P r o c e d u r e s . The  zooplankton  samples  manner. SCOR and M i l l e r in  5% n e u t r a l f o r m a l i n  made was  on  Miller  net samples  with  a modified  more  n e t samples,  than  Folsom  analysed were  i n the followinq  preserved  immediately  i n s e a w a t e r . Wet w e i q h t measurements were  p e r f o r m e d on 190 samples  Samples with  190  were  from  about  while size frequency the  SCOR  and  Miller  200 e u p h a u s i i d s were  plankton s p l i t t e r  analysis  which y i e l d e d  nets.  subsampled aliquots  15 of  size  1/2  operations. one  ,  n  where  In s u c h  of the f i r s t  was  subsamples. two  To  subsample)  c h e c k on  was  wet-sieved  to  the  retained  on  this  euphausiids,  were  material mesh  in  were  although  fraction.  c o n s i d e r e d a s an  for  biomass The  approximate  from  the  s i e v e to c o l l e c t  E  no m o i s t u r e  weights  were  g, and  sample  (or  which  was  c o d e n d . The  mainly  adult  plankters  and  numbers  of  juvenile amphipods,  occasionally galatheid A  paeifica  index  of  larvae  a l o n e g e n e r a l l y made size  euphausiid  initial  sieving  the zooplankton  fraction abundance  Each s i z e was  fraction  visibly  determined  was  was  re-strained  residue,  copepods, a l t h o u g h e u p h a u s i i d l a r v a l  c e r t a i n times.  0.001  this  surveys.  filtrate  mm  As  the  m e g a z o o p l a n k t o n b i o m a s s , the 5 mm  was  until  on  significant  mesh n e t t i n g ,  significant  this  30-90% o f t h e  after  IKMT  often  occurred  in  5 mm  the  l a r g e c o p e p o d s , and  at  determined  the c o n s i s t e n c y of  made  through  chaetognaths,  chiefly  were  s u b s a m p l e s were weighed. No  determinations  similar  a 0.35  weights  splitting  detected.  Height  up  number o f s u c c e s s i v e  c a s e s , t h e wet  method, o c c a s i o n a l l y bias  n i s the  stages  blotted  on  with  which  was  predominated paper  towels  t r a n s f e r r e d ( a b o u t 15 m i n u t e s ) .  on  a M e t t l e r balance, t o the  s t a n d a r d i z e d as grams  per  cubic  metre  Het  nearest  of  water  filtered. For fraction 60  81  The  the  wet-weighed s a m p l e s ,  were d e t e r m i n e d ;  C f o r 24  Mettler  of  h and  balance.  the  dry weights  s a m p l e s were d r i e d  cooled i n a desiccator  prior  i n an  for oven  to weighing  each at on a  ;  conversion factor  from  f o r m a l i n wet  weight  to  fresh  wet  16 weight  was  determined  samples  from  formalin  f o r about  weight Size  by  Saanich  wet  were  Biomass c h a r t s o f t h e 5 were  prepared  b i o m a s s v a l u e s and  Mar.-Apr. June - J u l y July August Aug.-Sept. Oct.-Nov.  1.421  Length  species  specimens scale  measured telson. vertical  fraction the  A  of  the  following  wt  Miller  net  p e r i o d s from  transect  wet  recordings:  75/10/,75/12 75/21,75/24 75/25 75/27 75/27,75/29 75/31,75/33  S t r a i t of Georgia; Saanich, S t r a i t of Georgia, Saanich, Saanich I n l e t Saanich I n l e t S t r a i t of Georgia, Saanich, S t r a i t of Georgia, Saanich,  Jervis Jervis Jervis Jervis  Measurements.  were  100  to  200  e u p h a u s i i d s p e c i m e n s were  to  F u l t o n (1968).  measured by  i n 1 ram s i z e from  the  mm.  tip  Juvenile  For s t a t i s t i c a l E  A  pacifica  of t h e r o s t r a l  selectivity  n e t and  through  and  each  analysis, body  p l a t e t o the  Saanich I n l e t , g e n e r a l l y animals  Miller  identified adult  means o f a b i n o c u l a r m i c r o s c o p e  intervals.  h a u l s a m p l e s from  s a m p l e s from  for  S D_.  Region  according  For  mm  *  * 1.15% o f wet wt + 2 . 2 2 % o f wet wt 94.2 ± 1.20% F r e s h  khz e c h o s o u n d i n g  t o t h e n e a r e s t 0.5  grouped  net  107  neutral  following  Cruises  A l i g u o t s of to  factor  Dry wt = 16.9 Dry wt = 17.0 F o r m a l i n wt =  mm  The  frozen  established:  Conversion  Period  previously  f o u r months b e f o r e r e - w e i g h i n g .  fraction  zooplankton  two  p r e s e r v i n g them i n 5%  I n l e t , then  conversion factors  5 mm 0.35  weighing  from  IKMT h a u l s comparison  they  were  length  was  t i p of  three or  month were measured.  the more  Additional  were measured t o of size  and  examine  distributions.  For  17 the S t r a i t  o f G e o r g i a and  mainly f o r M i l l e r net  and  A d u l t e u p h a u s i i d s were s e x e d ;  the  measured  spermatophores an  additional  margin  wide r a n g e  i n body  July  May  and  and  index  length August  length.  carapace  length  furcilia  larvae.  of  were  Linear  permanent successive  i t  parts,  moults,  and  can  i t can  i s , though,  and  technique of c o l l e c t i n g  distributions As  sensitive  absence  of  the  length  eye  to  was the  R e p r e s e n t a t i v e samples with analysed  for  the  1976.  months  Larval  a of  samples  measured f o r b o t h body l e n g t h of  body  length  on  f o r b o t h s e x e s o f a d u l t s and f o r  Distributions.  analysis be  was  euphausiids,  used;  applied  as be  of  to  applied  this  samples  may  which  bias  has  lacking qrow  t o l a r g e sample  which  the  method  animals  crustaceans  by  sizes.  the  qear size  obtained.  the euphausiid length d i s t r i b u t i o n s  by  or  to t h e p r o p e r t i e s of the sampling  more modes, t h e p o l y m o d a l  sugqested  behind  regression  such  It  presence  growth r a t e s  frequency  that  hard  and  comparison,  and F e b r u a r y  were computed  size  the advantages  was  from  Analysis of Length-freguency  technique  or  mm  were a l s o  To e s t i m a t e t h e age  commercial  o f body s i z e , c a r a p a c e  1975,  1975  IKMT,  noted.  o f the c a r a p a c e .  June  carapace  1.422  also  t o t h e n e a r e s t 0.1  posterior  January,  was  l e n g t h measurements were  although s e v e r a l for  As  and  net samples,  SCOR s a m p l e s were e x a m i n e d  attached  from  Jervis Inlet,  Hardinq(1949)  employed. I n i t i a l  analysis and  often  with  amplified  comprised  probability by  data r e d u c t i o n involved  two paper  Cassie(1950,1954) poolinq  of  each  18 month's  samples  individual lengths.  for  samples  a  for  Histogram  given  significant  p l o t s and  size  g r o u p s were computed  The  cumulative  region  variation  by a BMDP p r o g r a m , were  plotted  which t r a n s f o r m s a n o r m a l l y d i s t r i b u t e d deviations  modal  lengths  distributions identifying separate  from  and were  Euphausiid  among  standard  points  and  P5D  modal  on p r o b a b i l i t y  curve  into  deviations the p l o t s  of  1  mm  {Dixon,1975).  cause the l i n e  determined from  inflection  normal  normality  their  inspection  cumulative percentages i n the  percentages  line;  after  a  paper  straight  t o bend. for  polymodal  (Cassie,  t r a n s f o r m i n g each  Mean  1954)  by  mode i n t o  a  distribution. growth  rates  for  each sex  calculated  from t h e mean modal l e n g t h s .  equations  were  fitted  to  t h e growth  and age  group  von B e r t a l a n f f y d a t a f o r each  were  growth  sex  within  cohorts.  1.423  Length-weight Length-weight  euphausiid  mm  individually  pooled  from  on  Saanich I n l e t ,  were made f o r t h e March -  increment  balance.  determinations  samples  Jervis Inlet  Relationships.  of  body  wet-weighed  Linear  lenqth,  r e g r e s s i o n s o f ln(W)  d a t a f o r each  sex.  Strait  April  up  to the nearest  formalin-preserved  to  period. 25  0.0001 g on  o f G e o r g i a , and F o r each  specimens on  a  1  were  Mettler  l n { L ) were computed  on  1.424  Identification During  of  larval  permit  stages  stages  and  Saanich  Einarsson(1945), the  which  are  Stages. progress  separated  growth. Boden's(1950) d e s c r i p t i o n  calyptopes  for  History  development, e u p h a u s i i d s  post-naupliar  from  of L i f e  presence  was  seven Inlet.  used  by of  to distinguish  stages  of f u r c i l i a  Other  M a c d o n a l d (1 928)  references and  through  a  series  numerous m o u l t s t o the  E._  the t h r e e i n samples  paeifica stages  of l a r v a e  consulted  M a u c h l i n e (1965) t o  of l a r v a e o f Thysanoessa r a s c h i i  .,  of  were check  20 CHAPTER 2:. L I F E  2.1 L i f e  HISTORY, S I Z E STRUCTURE, GROWTH AND  History  Although are observed spawning  Stages  s m a l l numbers o f e u p h a u s i i d e g g s and l a r v a l during  period  late  is  April  from  , 1 9 6 9 ) . As  abundance in  can  and  similar  euphausiid  concentrations Inlet  second  October  late  a  the  the middle  main  of July  combined  plots  of  et egg  the p e r i o d s o f h i g h e r  and  June  by  (Figure  4).  A  appearance o f a high biomass o f of  Parsons  high  chlorophyll-a  e t a l . (1967) i n S a a n i c h  i n phytoplankton  ( F i g u r e 5) a l t h o u g h in  the  with  period  densities  o b s e r v a t i o n s were t a k e n  was less  1968 s t u d y by F u l t o n e t a l . . (1969). A  i n t e n s i v e spawning o c c u r s i n l a t e  as shown by l a r v a l  r e c r u i t m e n t i n September  1975 and by t h e p r e s e n c e  40%  the  Hay  1966. The t r e n d  than  until  Inlet,  c o n c e n t r a t i o n f o r 196 8, t h e p u l s e s  the  noted  period of less  September,  over  was  i n 1975  freguently  in  during  and  d u r i n g June  similar  seen  between  eggs  May  coincide closely  abundance  relation  Saanich  stages  S t e p h e n s e t a l . . ,1967 and F u l t o n  chlorophyll-a  spawning a c t i v i t y  phytoplankton  o f t h e 19 t o 23 mm  of spermatophores  female  euphausiids  August1974 and  attached  i n samples  to from  August 1975.  The diameter, one  be  in  early  ( F i g u r e s 2 and 3; d a t a f r o m ajU  MORTALITY  free-floating hatch  as n a u p l i i  metanauplius,  (Boden,1950). furcilia  instar  euphausiid  b e f o r e growing  three calyptopis  The  number  t o t h e next  eggs,  of  and  moults  i s highly  about  400  and m o u l t i n g  seven  furcilia  r e g u i r e d t o pass  ^um  in  through stages from  one  v a r i a b l e and d e p e n d e n t  on  21  . i  5 0 0 0 |  FIGURE 2. E u p h a u s i i d egq(o) and l a r v a l ( t ) a b u n d a n c e s i n S a a n i c h I n l e t d u r i n g J u n e a n d J u l y 1966, from o b l i q u e M i l l e r hauls (12m-0). D a t a from S t e p h e n s e t a l . . (MS, 1967).  temperature  (R.  Ross, p e r s o n a l  t h e r e a r e up t o a b o u t within  the  20  furcilia  different series,  development  of  pleopods,  Boden(1950)  encountered  samples  from  southern C a l i f o r n i a  summer.  The  frequency  communication).  setae 18  as  instars shown  and  or by  terminal  t y p e s amonq  Consequently, larval  the  distribution  deqree  spines.  500 f u r c i l i a  waters taken d u r i n q of l a r v a l  types of  Thus,  larvae i n  sprinq  and  t y p e s had s e v e n  22 lOOOr  ll  '  I  4  • t  )  1  1  1  MAY  1  1  "  1  *  • \  1  I -  ' • Ir  1  •  I  JUNE  1  •  1  1  1  '  JULY  FIGURE 3. Euphausiid egg(o), l a r v a l (t) and j u v e n i l e le) a b u n d a n c e s i n S a a n i c h I n l e t from 175m v e r t i c a l h a u l s d u r i n g May t o J u l y , 1968. Data from F u l t o n e t a l ^ (MS, 1969).  modes which Boden r e g a r d e d the  life To  history, check  euphausiid oblique in  part  of  developmental stages,  576  following Fraser's(l936)  on  local  euphausiid  Miller  tows May  gives the frequency furcilia  schematically  (15 m t o s u r f a c e ) and J u n e ,  distribution  staqe,  depicted.  taken  were  including  19  examined  a t weekly  1975 i n S a a n i c h for  of that  suggestion.  l a r v a e , i n c l u d i n g 357 f u r c i l i a ,  daytime during  sixth  as t h e a c t u a l s t a g e s  Inlet.  a l l staqes  from  from  intervals Figure egg  o f t h e 20 f u r c i l i a  6 to  types  23  !  j  1968  FIGURE H. Hean c h l o r o p h y l l - a c o n c e n t r a t i o n i n t h e u p p e r 20 m and e u p h a u s i i d egg a b u n d a n c e from v e r t i c a l h a u l s (150 m - 0) i n S a a n i c h I n l e t . Data from Fulton et al.. Curves f i t t e d by e y e .  (1969).  There positions additional third  i s g e n e r a l agreement of  furcilia  furcilia  through  F7  the  dominant types  stage  are l i k e l y  (F3)  (no.  with  Boden's  modes. 5 and  results  Differences 6)  and  due  the  include  two  a broadening  mode t o i n c l u d e t y p e n o .  underrepresented  on  11.  to a l a r g e r  of  the  Stages  F4  extent  of  24  FIGURE 5. Chlorophyll-a concentrations i n t h e u p p e r 10 m o f S a a n i c h I n l e t d u r i n g 1975. Mean ± S.p. for a l l stations sampled.  vertical  migration  (Mauchline The F3  fact  stage  during  and  experimental  the s u r f a c e l a y e r  by t h e o l d e r  furcilia  Fisher,1969). t h a t l a r g e r numbers  is  this  from  an i n d i c a t i o n  stage  that  of larvae a r e observed  t h e l a r v a e moult s e v e r a l  (Boden,1950). R o s s ( p e r s o n a l  support  in  for this conclusion  from  the times  communication)  has  observations  on  25 I  TS 7  I I  3 7  111  FURCILIA LARVAL TYPES  I .1  1000h  3 7  3 7  t .1 .1 '\ \ \ 111.1  500  Z3, 7  V V V  Z3 7 "J  2ND  ANTENNAL ENDOPOD UNSEGMENTED  r-r  8  9 C  100  ii  3 7 1 7  X \ VV  xxx  12  7  3 7  xx  1 7  W x S r  9 ^ 3 a 5 6  50  13  14  .15  ji 2ND  7  ANTENNAL / ENDOPOD \  10  3^  /'  SEGMENTED \  »  34 3 3  jrr..  ]8 1 1 1 I . >TT."X v» 1  \2o  x' X X X 1  1  -a ?Tx^=  1  3 2 3 1  IV  3  o  VI  11—I. I I I  I  II  E N MCICIICIII 1  I  i i i i i i i • i  i  t  2 3 4 5 6 7 8 9 10 1112 13 14 15 1617 1819 20 FURCILIA L A R V A L T Y P E S  FIGURE 6. Frequency o f euphausiid l a r v a l types encountered i n M i l l e r n e t s a m p l e s d u r i n q May and June 1975 i n S a a n i c h Inlet. abbreviations used are E=egg, N=nauplius, M = m e t a n a u p l i u s , CI t h r o u q h C I I I r e f e r t o c a l y p t o p e s s t a g e s , and TS=number o f t e l s o n s p i n e s . Roman n u m e r a l s I t h r o u q h VI r e f e r t o f u r c i l i a s t a q e s F1 t o F 6 .  the moulting Field (about  of laboratory-raised estimates  4.5 mm  Stephens  of  f». p a c i f i c a  developmental  i n body l e n g t h )  larvae.  time  were made from  e t a l . , ,1967 ( F i g 2 ) . a s s u m i n g t h a t  to  data  t h e F3 s t a g e collected  large  i n e u p h a u s i i d egg a b u n d a n c e a r e t r a n s m i t t e d t h r o u g h stages,  the  developmental  time  from  t h e d u r a t i o n between c o r r e s p o n d i n g  by  fluctuations the  larval  egg t o F3 c a n e s t i m a t e d by  peaks i n egg  and  F3  larval  26 abundance.  In  Fig  estimated  2)  days in  were  (Mean the  (compare  F3  higher  at  manner to  four  have  ± S.D..).,During  upper Figure  intermediate  to  this  m 7  between  12 a n d than  30  the  8 C  of  for  a  this  estimate  of  F3  larvae  developmental time period the  Saanich  Inlet  197U-75).  laboratory  (Boss,  groups  The  estimates  20 d a y s  of  average  was  above of  27.3  ±  1.5  10 a n d  11 C  estimate  is  developmental  by P e a s e (1968)  cn  temperature  between  personal communication), of  (numbered  but for  times  it the  is same  period  i n Saanich  running  Inlet.  mean f o r egg  recognition  However,  and  larval  of l a r v a l cohorts  his  use  of  a b u n d a n c e s may  and  thus  a  three-point  have b l u r r e d  the  duration  of  the the  stages.  2.2  Larval  Survival  Estimates stages l e s s and  from  (eg. of  of  than  larval  F i g 3)  the  4.5  rates  mm  (nauplii,  to juvenile  presented  by  stage  175  survival (Z=-lnS) time  and  (S=N2/M1) values  t 2 and Egg  N1  m vertical and  ±  to J u v e n i l e  larval  mm) (4.6-8 mm)  furcilia  F1-F3)  juvenile  data plots peaks  the f o l l o w i n g  (Sicker,1958) i s the  mortality  abundance a t  t1:  S = 0.42 Z = 0.93  ± ±  0.17 0.41  S = 0.022 ± 0.0083 Z = 3.87 ± 0.39  40%  in  the  transition  from  egg  from  to j u v e n i l e  early  larval  furcilia; furcilia  size  (age)  stages  survival to  i s o n l y about  Population Size S t r u c t u r e i n Saanich the  larval  S = 0.057 ± 0.015 2 = 2.90 ± 0.28  i s high f o r the  in  to  were made from  and  S.D.,), where N2  o f t h e eggs s u r v i v e t o be  Changes  egg  h a u l samples y i e l d e d  5.7%  2.3  egg,  to J u v e n i l e  Mortality  survival  (4.6-8 mm)  abundance a t time  (< 4.5  from  c a l y p t o p e s and  instantaneous  (Mean  i s the  to Larvae  Larvae Egg  20  survival  F u l t o n e t a l . . (1969) . L o g a r i t h m i c  abundance f o r c o r r e s p o n d i n g  from  of  as o n l y rises  juvenile.  to  about about  Overall  2.2%.  Inlet  structure  of the  euphausiid  28  population into  1976  through year.  in  Saanich  {Fig  the  length  Resolution  Inlet  8 and  9;  were Table  frequency of  sampling  effort  and  following  discussion  the  followed 1).  {L-F)  1975  will  Dp t o  concentrate  four  1974, modes  distributions  modes i s  consequently  during  better  larqer on the  due  1975  and  progressed  during to  each  increased  sample  sizes.  1975-76  data.  The  29  TABLE  1. M o n t h l y mean i n Saanich I n l e t  Mo Sex 1974  S p r i n g , 73 Mean ± S . D .  Jan. F Feb. M F Mar. M F Apr, M F May. M Aug. M F Sep. M F  11. 9 ± 12.0 i 12.1 ± 12.1 ± 12.4 ± 11.5 + 11.7 ± 13.5 ± 17.7 ± 20.0 ± 18.5 ± 20. 1 ±  0.97 0 . 94 0.96 0 . 90 1. 00 0.83 1.08 1.40 0.70 0.51 0.68 1.02  1975 Jan. M F Feb. M F Mar. M F Apr. M F May. M F Jul. M F  Spring  75  A  Aug. M F Oct. M F Nov. M F  ±  1.02  10.7  ±  2.04  12.5  + 1.94  12.3 13. 6 14. 8  In  0.75 1. 59 0 . 89  ± ± ±  1975,  cohorts,  two  entered  most  the  about  This 3  A  1.80 0.70 0.73  18.3 18.8  ± ±  0.32 1.0 2  17.9  ±  0.54  19. 7 18.7  ± ±  0.88 0.91  Fall  25  ±  8.4  x 0.73  groups adult  of  2.0  + 0.75  8.5  ±  0.58  13. 1 ±  0.65  20. 2  7.5  ±  recruits,  14.7  0.8 3  population.  Of to  (curves  I  and J ,  May  to  9-12  the these, the  Figure mm  in  i: 1 . 2 9  8 . 3 + 0.51 8. 3 ± 0.51 1 0 . 7 ± 1.96 8 . 7 ± 1. 10 1 2 . 5 ± 1.00  19.3 ± 0.97 2 0 . 2 + 1.26 19. 1 ± 0.9 1 2 0 . 2 ± 1.08 1 9 . 3 ± 0 62 20.0 ± 0.50  contributor  in  f a l l 24 Mean A  1 4 . 9 ± 1.21 1 5 . 2 ± 1.13 1 3 . 9 ± 1. 13 1 3 . 9 ± 1.13 14. 1 + 1.08 1 4 . 2 ± 1.67 1 4 . 7 ± 0.94 16. 1 ± 0.83 16. 2 ± 1.00 17.0 + 0.75  1.05  4. 3  sex f o r e u p h a u s i i d c o h o r t s 1974 a n d F e b r u a r y 1 9 7 6 . S p r i n c j 74 Mean +  D.  ± ± ±  cohort mm  23 + S  14.8 16.0 16. 1  significant  population. from  Fall Mean  14. 4 + 0 . 7 0 12. 5 ± 1.67  1976 Feb. M F M  was  3.0  b o d y l e n g t h s by between J a n u a r y  0.70 0.67 0.78 1.13 1 10 0.70  18. 2 18.2  0.94 0.78  ± ±  and  fall  spring  mode  February 10)  1.83  15. 8 ± 15.4 + 16. 1 ± 15. 8 ± 16 0 ± 16.0 +  spring the  +  grew  July.  1976 rapidly  The  L-F  FIGURE 8. Length frequency d i s t r i b u t i o n s of E p a c i f i c a from S a a n i c h I n l e t , 1974. The m o n t h l y s a m p l e s were c o l l e c t e d by v e r t i c a l h a u l s w i t h a SCOR net(100m - 0 ) . t  diagrams(Figures show  very  9ft and  strong  B)  recruitment  A u g u s t . Growth s l o w e d  during the f a l l .  a  length  cohort was  of  mm.  The  about  were g r o u p e d a s  11-15  into  as m a t u r a t i o n  declined body  f o r v e r t i c a l ana  Little  14  this  proceeded  petasma on mm;  immatures. change  horizontal cohort and  to t h i s  By  November, t h e body  for July food  time  length  members o f  had  modal  ana  supply  m a l e s became e v i d e n t  up  in  sampling  at the  range  occurred  by  31 1000 J A N 75  FEB 75  MAR  APR  75  75  soot-  lOOf-  .10  10  4000 A U G 75  JUL 75  O C T 75  1000  50 Or-  1  I  50  \  z  IO  1  '^1 5 10 15 20 BODY L E N G T H mm  25  FIGUBE 9. Length frequency d i s t r i b u t i o n s o f 1^ M c i f i c a from S a a n i c h I n l e t , J a n . 1975 t o Feb. 1976. Section A samples were taken by SC0R v e r t i c a l haul(150m - 0 ) ; S e c t i o n B i s f o r h o r i z o n t a l s a m p l i n g a t n i g h t i n t h e upper 25 m with Miller nets.  February  1976; t h e s p r i n g  mode t h e n c o m p r i s e d  about  90%  of  the  sampled p o p u l a t i o n . The October,  fall  cohort,  had r e a c h e d  7-9  which mm  appeared  as  3-5  ram  by F e b r u a r y b u t a c c o u n t e d  larvae i n for  only  BODY L E N G T H mm  FIGURE 9 ( c o n t i n u e d ) .  3% o f t h e sampled Members to  spawn  population.  of the s p r i n g cohort  f o r the f i r s t  time  mature o v e r  Females  eggs(Brinton,1976).  with  attached  Females  and  appear  i n the f o l l o w i n g s p r i n g , according  to o b s e r v a t i o n s o f spermatophores attached group.  winter  to  females  spermatophores  (19 t o 21 mm)  from  the  of  this  have  ripe  older  fall  r  t  1  r-  1  1 •  i  •  i  1 — — i  •  i  i  1  1  1  i  i  i  I  ;  i  i  i  i  i  22  o  FIGUBE 10. Mean body l e n g t h s and f i t t e d von B e r t a l a n f f y g r o w t h c u r v e s f o r f e m a l e ( a ) , male{e) and immature{i) E paeifica cohorts i n S a a n i c h I n l e t d u r i n g 1974-75. L e t t e r s A-J r e f e r t o t h e c u r v e s l i s t e d i n T a b l e 2. A  cohort  a l s o spawn i n t h e  The a b o u t 22 continues  fall  cohort  spring.  disappears  months a f t e r i t s o r i g i n . to  grow  September, f e m a l e s  in {now  f r o m t h e p o p u l a t i o n by The  mean  body  19-22  mm)  spring size.  In  apparently  cohort, late spawn  July,  however, August for  and the  i  hi  i  I  o i  J  1  I976  F  *5  34 second by  time.  In t u r n , t h i s  January, about lithin  rates Each  19 t o  a given  of  the  months a f t e r  cohort  the  length  differ  frequency  composite  of  modes  plots  from Table  For  the  g r o w i n g s e a s o n f r o m March  growth i n l e n g t h (1938) g r o w t h  rate  is  correlation  lengths period, plot  is  an  the  of ,  correlation  To  for  two  the  given  is  show  the  sexes,  in Figure  November, E. the  males.  presented  von  10.  paeifica  Bertalanffy  K i s the t  constant  i s the  curves  2  - t )  (  * 1^).  The of  (  t^,  from  hypothetical  coefficient,  10,  first  where 1, , 1^ against the the  are average length  a 0  t  0  the  estimated  is  -K  is  and  age, the  values  of  as  w e l l as  the  2) .  (The  the  the  growth  mean  length axis In ( L ^ t, in  body  for of  the this  1^)  2 i n d i c a t e s the  was  months.  Y-intercept  estimated (Bicker,  r, i n Table  "age"  The  plotting  L ( G u l l a n d , 1969) . Next,  relation which  involved  i n t e r c e p t on  plotted against the  i n Figure  determining  r , h a v e been t a b u l a t e d ( T a b l e  t ,  estimate  and  slope  l n L t f + Kt  length,  growth c u r v e s  times  0.5(1,  calculated The  for  (1^ - l , ) / ( t at  by  growth  of the  each sex.  zero(Bicker,1958;Gulland,1969).  coefficient,  of the  increment  those  1 are  t o about  described  asymptotic  constants  fitting  rates  o f c h a n g e i n q r o w t h , and  when l e n g t h these  well  inferred  equation:  where Lo© i s t h e the  is  from  for  growth  mean body l e n g t h s  the  population  appearance.  distributions  d i f f e r e n c e s i n the i n f e r r e d of  from the  its first  of euphausiids,  females g e n e r a l l y  mode i n t h e  therefore  20  mode d i s a p p e a r s  1958). goodness  is The of  35 fit  f o r the l a t t e r  TABLE  plots.  2. Growth c o n s t a n t s f o r v o n B e r t a l a n f f y e q u a t i o n s f i t t e d t o S a a n i c h I n l e t d a t a on mean body l e n q t h by s e x a n d c o h o r t p l o t t e d i n F i g u r e 10. Mode  Curve  K  A B  F Sp73 H Sp73  0.744 0.236  20.3 21.1  10.62 8.11  0.99 0.999  C D  F Fa73 Sp74  0.276 0.377  20.1 15.7  7.68 0.11  1.0 0.999  E F  F Sp74 N Sp74  0. 451 0.287  21. 3 21.1  9.20 7.70  0.980 0.99  G H  F Fa74 M Fa74  0.545 0. 455  16.1 16.3  1.46 4.70  0.983 0.983  I J  F Sp75 n Sp75  0.400 0.354  13.4 15.3  -.40 -.51  0.986 0.982  In Saanich I n l e t , female same  E  than  Nemoto's (1957)  North P a c i f i c  females  sampled  the i n f e r r e d  pacifica are usually  t  cohort.  western  growth r a t e s  higher than data  a l s o suggest  for  but  following  onset  The  growth i n m a l e s ,  faster  of  appear  there i s evidence  m a t u r a t i o n , a t about though,  higher  mortality  (compare  observed  or inferred  qrowth r a t e  less  the  w h i c h have d i e d qrowth both  rates  contribution  are  sexes; t h e deqree  h i q h e r i n males.  of  actually  I t follows  underestimates  o f males i n t h e from  the  smaller  t o be t r u e f o r t h e which s u g g e s t s that  of  females  coupled  with  Consequently, the  true  qrowinq that  that  (Brinton,1S76).  i s apparently  of the f a s t e r  i n the i n t e r v a l .  second-year  males a r e  11 mm  B i c k e r , 1969) . is  of  Ej. p a c i f i c a  that adult  o f t h e same age. T h i s may  population,  those  t h e t r u e growth r a t e o f males i s g r e a t e r t h a n  rate  r  ^ 0  the  qrowth  individuals  the  inferred  o f t h e t r u e qrowth r a t e s f o r  underestimation,  thouqh,  is  likely  36 Support  for  higher  growth  Figure  10.  Curve  about  11  to  size  between  lead  in  season.  rates J  March,  November,  when  evidence  Saanich  Inlet,  categories  when  characterise  a  growth  Inlet  rate. to  17  number mm i n  tended  higher  The  though,  when  the  and The  first  values  is  not  are  for  Georgia  the  0.71.  ratio  was  had  the  By  died.  combined  populations. of  limited  Table  2  support fall  growing length,  on  was  males  second  to  a  into  four  seasons  the  L^,  since  are  will E  often  pacifica  x  season,  and  20  asymptotic  lengths  for  males  in  growth  both  season  potential  significant  compared  the  a  growing  females  higher  such  of  described of  how  the  the  from  1 mm i n  in  F)  in  over  egual,  seasons  full  The  :  J  I  were,  constants  asymptotic  its  for  of  give  number  growing  a  difference  also  (M  presented  growth  of  than  cohort  were  10 c u r v e s  second season.  indicating  season.  They  of  have  H and  curve  eroded  ratio  Strait  the  than  H a n d G show  this  be  pacifica  curves  difference  sex  will  The  slope  proportion  and  sex  in  lengths  for  3).  a  E.  in  gradually  the  type  experienced.  its  possibly  this  (Table  22 mm d u r i n g be  body  statistics  13 t o  to  males  male  evident  in  be  much h i g h e r  of  the  is  Curves  can  the  mean  according  has  reaches  growth  that  a higher  February.  Jervis  below  male  cohort  by  the  Further  presented  has  2 mm l o n g e r ,  indicating  Summary  females  mm, r e s u l t i n g  sexes  about  higher  than  apparent In  hypothesis  (male)  14  average,  0.21,  the  with  at  within  the  Student's  95%  to  groups, a  given level,  t-test.  37 TABLE  3. Summary o f S a a n i c h I n l e t for von B e r t a l a n f f y e q u a t i o n s and s e a s o n . Mean ± S.D.  Sex^Season  K  E. p a e i f i c a qrowth c o n s t a n t s o f T a b l e 2 a c c o r d i n q t o sex  i ^ i l l l  t Jmol o  F.1 F.2 F.1 6 2  .44 + .09 .49 ± . 24 .47 ± . 16  15.1 ± 1.46 20. 6 ± 0.64  -.15 ± .36 9.2 ± 1.5  M. 1 M.2 M. 1 5 2  .41 ± .07 .26 ± .0 1 .33 ± . 10  15.8 ± 0.71 21.1 ± 0.  2.1 ± 6.8 ±  2.4  Population  Size Structure in Jervis Inlet  3.7 1.9  and t h e S t r a i t o f  Georqia.  Similar E  y  paeifica  Georqia  studies  provide  for  Inlet  Jervis  correspondinq  Jervis period  British  mean  are  chanqes  Jervis  size  cohorts  frequency  analysis.  structure  the  the  of  S t r a i t of  life  cycle  of  Columbia c o a s t a l waters. L-F histoqrams presented  constructed  in  Fiqure  11,  by s e x and c o h o r t from  these Inlet  data  with  whose  to  the  development  are  presented  population,  traced  the  durinq the  recruitment  was  the  appearinq i n  s t r u c t u r e becomes h i q h l y complex  from J u n e t o November due  juvenile  size and  on  12. I n c o n t r a s t t o t h e S a a n i c h  Inlet  in  Inlet  information  body l e n q t h s  4; qrowth c u r v e s  Fiqure  in  further  in  in  the  populations  E. p a e i f i c a  Table  on  of by  four length  38 TABLE 4. M o n t h l y mean body lengths by s e x f o r E. p a c i f i c a c o h o r t s i n J e r v i s I n l e t between A p r i l and December 1975. Mo.Sex  S p r i n g 74 Mean ± S.D.  Apr. M F Jan. M I/F Jul.M I/F Sept.M I/F  18.5 ± 18.7 ± 20. 3 ± 20.6 ± 20.0 ± 20. 3 ± 20.0 ± 20.9 ± Sum.B  0.71 0.70 1.08 0.67 1.22 1.34 0.70 0.86  10.7  ±  0.81  11.7 7.0 12. 0 11.8  ± ±  Oct. M I/F Nov. M I/F Fall I Dec. M I/F  The more  1.61 1.10 + 0.70 ± 1.64  13.6 14.0 17. 1 18. 5 17.2 17.4 17.5 17.0 I 7.8 20.0 19.5 20. 1 19. 3  ± 0. 91 ± 0. 65 + 1. 42 + 1.08 + 0.70 + 0. 27 ± 0. 41 ± 0.63 ± 1.34 ± 0. 54 ± 1.53  20.0 19.8  ± 0. 58 ± 1. 91  S t r a i t of Georgia  complex  than  to t h a t o f J e r v i s distributions results  Summer 74 Mean ± S.D. ±  o f L-F a n a l y s i s  Inlet  12.0  ± 0. 81  14.5  + 0.78  17. 1 16.4 17.4 16. 1  ± 0.91 + 1. 10 ± 0.67 + 1.51  16.2 15.2  ± •1. 40 ± 1.59  of  of  Georqia  the  Strait  Georqia  i n Fiqure  population  the recruitment  11.4  ±  13.0  ± 0.62  16.2 15.2  ± 1.40  E^ p a c i f i c a  detail.  Length  a r e qiven  a r e shown i n T a b l e  qrowth c u r v e s  7.0 ± 1.37 1, 45  ±  1.59  i s  also  population, but i s s i m i l a r  in  the derived  October with  9.3 + 1. 88  except  with  of  1. 88  population  for Strait  Sum.A 15 Mean ± S.D.  + 2. 26  t h e Saanich Inlet  S p r i n g 75 Mean ± S. D.  5  and  frequency  i n F i q u r e 13; are  14. As i n J e r v i s  increased  o f f o u r new c o h o r t s .  durinq  plotted Inlet, June t o  BODY  L E N G T H mm  FIGURE 11. length f r e q u e n c y d i s t r i b u t i o n s o f E._ p a c i f i c a from J e r v i s I n l e t , A p r i l t o December 1975. Samples were t a k e n by h o r i z o n t a l hauls with M i l l e r nets.  40 TABLE 5. M o n t h l y mean body cohorts i n the S t r a i t F e b r u a r y 1976. , Mo.Sex 1975  S p r i n g 74 Mean ± S.D.  Mar.M F Jun. M I/F Jul.M I/F Sra73F Aug. M I/F Sept.M I/F Oct. M I/F  15.3 16.0 17,6 20. 2 18.9 20. 3 23. 0 19.0 20.4 19.6 21.0 20.0 21. 1  + 1. 37 + 2.12 ± 0.59 ± 1.08 ± 0.73 ± 0.70 ± 0.71 ± 0.78 0.94 ± 1.02 ± 0.97 ± 0.70 i: 1.29  11.9 11.7 15.4 17.8  Nov.M I/F 1976 Feb.M F  20. 1 + 0.75 20. 3 ± 0.94  17.7 16.8  Although in  the  recruitment summer from  11  ± +  than  and  and  Inlet,  and  spawning  with  September-October strongest  8.0 ± 0. 71  1. 00 1.08  4-5 mm  Strait  6.6 + 0.66  12.0  ± 1. 34 A  8.9 ±  13.2  ±  17.7 16.9  A 12.3 ± 1.59 Fa 5.5 3.20 + Fa 7.7 0.81 00 1. t 08 B 10.9 ± 1. ± 1.08  14.8 16.2  ± 1. 10 ± 1. 37  Georgia  coincide  suggested i n timing  areas  11.7 12.6  1. 29 1.21  ±  +  counted  samples,  the  compared  to  activity  Saanich  Inlet  was c o n f i n e d t o May a n d September. I n appeared t o o r i g i n a t e  cohorts  12).  In  starting  the S t r a i t  appeared i n J u l y  periods  with  5.9 ± 0.94  B  h e a v i e r spawning  h e a v y s p a w n i n g i n J u n e and September  The  1. 53  1. 24  t h e sampled p o p u l a t i o n s d u r i n g t h e  smaller  juvenile cohorts  t 0. 50 A  of  recruitment  (Figure  10.0  were n o t r o u t i n e l y  13) s u g g e s t s  heaviest  June,  1.02 1. 02 0. 48 0. 83  2. 04 1. 02 0. 91 1. 37 0. 91 ± ± 1. 08  of juveniles into  (Figure  Summer 75 S p r i n g 75 Mean ± S. D. Mean ± S. D.  ± ± ± ±  June t o August i n t h e s e  Jervis  13);  + ± ± ±  16.7 16.0 16.3 16.3 18. 1 17. 1  Inlet  where s i g n i f i c a n t  May  Summer 74 Mean ± S. D.  larvae less  Jervis  lengths by sex f o r F/, p a e i f i c a o f G e o r g i a between March 1975 and  the  of  intense  periods  of  in  July  from and  of Georgia, the  and O c t o b e r  (Figure  i sindicated.  spawning higher  appear  to  phytcplankton  41  24  FIGURE 12. Mean modal body l e n g t h s and f i t t e d growth curves f o r female (a), male(e) p a e i f i c a i n J e r v i s I n l e t d u r i n g 1975.  abundance  in  Jervis  Inlet  determined  by c h l o r o p h y l l - a  inference  is  lower for  more  frequency  these areas.  appears  to  and  Strait  and  than  Georgia  a lack  f o r Saanich I n l e t of d a t a on egg  Nevertheless, the Jervis Inlet  match w i t h  of  Bertalanffy immature(i)  c o n c e n t r a t i o n ( F i g u r e 15),  tentative  of sampling  the  von and  the h i g h  level  but due  this to a  abundance  c o h o r t from  of c h l o r o p h y l l - a  as  June  i n June,  42 while  the S t r a i t  likely  were  of Georgia  spawned  cohorts  during  from  June  the phytoplankton  and  September  blooms i n t h e s e  months.  Following mm)  where  gonad  assimilated cohorts  r a p i d growth t o t h e e a r l y a d u l t s t a g e development  e n e r g y , t h e new S t r a i t  merged  or " p i l e d  w h i c h were s t i l l recruitment  into  an  the  16 t o 18 mm  of  Georgia size  larger  of Georgia  older  18  mm  mode  size  to  15  portion  of  and  Jervis  with  older  cohorts  The  strong  range.  tends t o lower  Rn example o f " p i l i n g  Inlet  t h e mean body  up" o c c u r r e d  the  spring cohort  (Figure  ( c u r v e s G5 and G6)  1 4 ) . By F e b r u a r y  reached  t h e e a r l y summer  cohort  ( c u r v e s G7 and G8) h a d e v i d e n t l y j o i n e d t h a t g r o u p a s w e l l . corresponding  mean  dropped, l i k e l y selective late  body  and  fall  Jervis  Inlet  during  1975 ( F i g u r e  the  cohorts  population  two  12).  In  recruitment  ( c u r v e s G9,10 and 11)  cases the  of  and  apparently  10 a n d 13 mm.  "piling  first,  sexes  At t h e same t i m e , t h e  the  up"  E. p _ a c i f i c a  1 and 2, l i k e l y  up" 19-22  In the  developed mm  spawned i n l a t e  example i n v o l v e s m e r g i n g o f  3 and 4) w i t h  the S t r a i t  "piling  of  The  mode  i n s p r i n g 1974) was j o i n e d i n September and O c t o b e r by  1 9 7 4 ) . The s e c o n d  In  t h e modes f o r b o t h  modal g r o u p between  younger a d u l t s ( c u r v e s  (curves  of  due t o t h e c o m b i n e d e f f e c t  merged t o form a s e c o n d  (spawned  lengths  mortality of larger individuals.  summer  in  male and f e m a l e modes i n November f o r t h e S t r a i t  when  range  a  up" ( B r i n t o n , 1 9 7 6 )  i n t h e 15 t o  l e n g t h o f t h e assemblage.  that  requires  (11  t h e e a r l y summer c o h o r t  of Georgia reduces  population  the  and J e r v i s  the to 2  number or  3  Inlet  data,  during  the  spring  (curves the  of recognizable  summer mode  5 and 6) .  process  of  modes i n t h e  late  fall  and  43 10000}MAR 75  JUN  75  JUL 75  50001-  1000  soo  100  •50 E o  "5  lO  15  20  10  B O D Y L E N G T H mm  10000  50001-  1000*-  500  5 10 15 20 BODY LENGTH m m  FIGURE 13. Length f r e q u e n c y d i s t r i b u t i o n s o f E. p a c i f i c a from t h e S t r a i t o f G e o r q i a , March 1975 t o F e b r u a r y 1976. Samples were c o l l e c t e d by M i l l e r n e t h o r i z o n t a l tows.  winter, fall.  from As  the 5 or 6 c o h o r t s observed  a result  the o v e r a l l  populations i n these population  in  the composite Further  Saanich  Georgia  and J e r v i s  to and  t h e data 14.  Inlet  cohorts Inlet  constants recorded  structure  similar  although between  comparisons o f t h e  E. p a e i f i c a  growth  appears  modes may v a r y  within  the  areas  size  be  and e a r l y  o f the euphausiid  to  the  E. p a e i f i c a  recruitment  into  areas. of made  population data.  f o r the  summer  relative  growth  can  during  males with  Table  von B e r f a l a n f f y  and  females  the S t r a i t o f 6a,h  presents  equations  i n T a b l e s 4 and 5 and p l o t t e d  fitted  i n F i g u r e s 12  45 TABLE 6 a . G r o w t h c o n s t a n t s f o r von B e r t a l a n f f y equations fitted t o J e r v i s I n l e t d a t a o n mean b o d y l e n q t h b y s e x , p l o t t e d i n F i q u r e 12. Curve  Mode  K  t  r  —o  1 2  F Sum74 H Sum74  0.488 0.325  19.8 20.9  8.74 8.42  0.994 0.995  3 4  B Spr75 F Spr75  0. 434 0.267  18.8 21.0  0.49 -.18  0.993 0.998  5 6  H Sum A75 F SumA75  0.224 0.360  21.4 17.2  -.28 0.03  0.999 0.999  7 8  M SuraB75 F SumB75  1.023 1.045  12.2 12.0  0.74 0.64  0 . 999 0.98  von  TABLE 6 b . G r o w t h c o n s t a n t s f o r to S t r a i t of Georqia data p l o t t e d i n F i q u r e 14. Curve  Mode  equations fitted lenqth by  K  r  G1 G2  F Spr74 M Spr74  0.484 0.220  21.4 21.5  8.42 5.65  0.993 0.992  G3 G4  M Fa F Fa  74 74  0.298 0.198  19.1 19.3  4.93 3.39  0 . 983 0. 993  G5 G6  M Spr75 F Spr75  0.295 3.352  21.2 18.7  0.78 0.73  0 . 986 0 . 98  G7 G8  F SumA75 M SumA75  0.228 0.280  18.9 16.3  -.39 0.50  0.998 0.994  G9 G10 G1 1  F SumB75 M SumB75 M Fa 75  0.820 0.470 0.338  12.7 12.2 13.7  0.88 -.40 0.51  0 . 996 0.963 0. 999  As i n cohorts  compared  the  in  somewhat  of  Bertalanffy mean body  Saanich  their  first  faster to  Georgia  Inlet year  qrowth  data, {curves  after  the corresponding cohorts  {Figure  qrowth 3,5  14),  and 7 in  11-12  females.  curves  mm b o d y For  males  of  Jervis  Fiqure lenqth  12) for  the f i r s t - y e a r have  higher  Inlet show males Strait  inferred  46  FIGDBE 14. Mean modal body l e n g t h s and f i t t e d von B e r t a l a n f f y growth curves for female(a), male (e) and immature(i) I i p a e i f i c a i n t h e S t r a i t o f G e o r g i a d u r i n g 1975.  growth  in  curves  G3  F e m a l e s i n c u r v e s G7 corresponding February mortality An  males.  and and The  G5  than  G9, gap  makes t h i s i n f e r e n c e may  a l s o be  interesting  a factor  for t h e i r  though,  apparently  i n sampling more  between  tentative  over t h i s  observation  female c o u n t e r p a r t s .  from  as  outgrow  the  November  and  differential  period. the l i s t  o f Lv> v a l u e s i n  Table  6a,b i s t h a t t h e a s y m p t o t i c  early are  summer  c l o s e t o those  growth span  to of  final  11  to  temperature rate  had  i n Jervis  o f t h e second adult size 12  months  in  line  o f f the coast  the  spring  and t h e S t r a i t  year  adults,  might i f  of  Inlet  food  suggesting  availability  with  fall  observations  of Oregon  and  E  that  in a  and w i n t e r . of  and  of Georgia  h a v e been c o m p l e t e d  not d e c l i n e d i n t h e l a t e  o f growth i s  populations off  cohorts  lengths  x  life water This  paeifica  ( S m i l e s and P e a r c y , 1 9 7 1 ) and  southern C a l i f o r n i a ( B r i n t o n , 1 9 7 6 ) . Ml  12h  x JERVIS INLET » STRAIT of GEORGIA  10  £ oi2  JUN  _J_  JUL  AUG  SEPT 1975  OCT  NOV  DEC  FIGDBE 15. Mean c h l o r o p h y l l - a c o n c e n t r a t i o n s i n t h e u p p e r 10 m o f J e r v i s I n l e t and t h e S t r a i t o f G e o r g i a d u r i n g 1975. B a r s i n d i c a t e one s t a n d a r d d e v i a t i o n .  The  t e n d e n c y f o r t h e m a l e s ' growth c u r v e s  to  have  higher  48 asymptotic  lengths  Jervis Inlet comparing growing  and  examined  Saanich I n l e t  male and seasons  significant  was  female showed  that  a t t h e 95% l e v e l  on  paired  significant  male and  difference  of  K  in  first  (t = 2.21, growing  P < .05)  the  95%  female  probability components  Student's  t-tests growth  the  von  p o p u l a t i o n s e x p r e s s e d as  second growing TABLE  in  the  season. Similar  ( T a b l e 7 ) . In c o n c l u s i o n , t h e i n f e r r e d  varies significantly  second  t h e d i f f e r e n c e between s e x e s  between  sexes  G  of  was  second  statistical  level  of  t-tests  and  at  cohorts.  sampled  of Georgia,  t  and  results  Strait  f e m a l e v a l u e s f o r L«>and  c o n s t a n t s between male The  the  cohorts; paired Student's  values  s e a s o n , but n o t i n t h e f i r s t tests  for  revealed  E  x  i n these paeifica  are l i s t e d  below  o f E, p a e i f i c a  Bertalanffy  within  no  in  equations  cohorts  in  their  season.,  7. R e s u l t s o f S t u d e n t ' s t - t e s t s on p a i r e d v a l u e s o f von B e r t a l a n f f y constants f o r sexes w i t h i n E paeifica cohorts. A  Constant  Season  tlxiSL  n-1  ti£alc L  Probj.  A  K K  6 5  1. 94 2.02  0.93 2.21  0.20 < .05  1 2  L CO L co  6 5  1.94 2.02  0.53 1.37  0.30 0. 15  1 2  to to  6 5  1.94 2.02  0.10 1.86  0. 45 < .10  males  evidence f o r  selective  mortality  of  faster  s h o u l d be c o n s i d e r e d i n c o n n e c t i o n w i t h growth  change i n sex r a t i o maturity  the  =  1 2  The  the  if  when  (M :  for  the  the sexes are f i r s t  c o h o r t d i s a p p e a r s from relative  F)  amount  of  range  discernible  t h e sampled time  size  spent  growing  rates. from  (11-12 mm)  The  early until  p o p u l a t i o n i s an i n d e x o f at  the  various  size  increments. are  Significant  likely  full  due  adult  increasing Inlet,  body s i z e  1975-76. On  the  sex (X  =  2  from  1.34,  and  12 mm  1 (X  0.80  females  2  a t 18 and  at  are  12  19 mm  and  Note,  = 5.00,  was  largely  early  spring  The  the  to  on  more  abundant  Similarly,  the  body l e n g t h ,  than  1 u n t i l the l a t e  14 mm).  At e a r l y  length  than  P < 0.05,  f o r 18 and  the M : F r a t i o of  19  1.29  and  larger  egg  from  ratio  below  1 (X* = 4 . 1 0 , P  may  sexual  the apparent  be  <  19  about 0.05).  mm i n  sex r a t i o  maturing  which  as  a t about  10-  is significantly  seem  must use  increments  a t an  i n the  such  males a r e d i s c e r n i b l e males  mm.  interpreted  characteristics  to  grow  more e n e r g y  production. Consequently  size  at  f o r t h e S t r a i t of G e o r g i a p o p u l a t i o n  sex  females  mm  population i s s i g n i f i c a n t l y greater  maturity the  the  mean  d e v i a t e s i g n i f i c a n t l y from 1  males a r e b e g i n n i n g t o be e x p r e s s e d  11 mm  development  taken during  a h i g h p r o p o r t i o n o f m a l e s a t 14-15  in  with  (0.85) i s n o t s i g n i f i c a n t l y  do n o t  manner. As s e c o n d a r y  petasma  the  mm  (or  Saanich  when t h e m a j o r i t y o f f e m a l e s were a t 11-13  variation  following  from  to  According to a chi-sguare  P < 0.05).  X* = 3.51,  up  mortality  P < . 0 5 ) . A l l o f t h e mean r a t i o s  14  ratio  change i n sex r a t i o  mm.  however, t h a t  r a t i o at due  in  apparently  mm  are s i g n i f i c a n t l y d i f f e r e n t h i g h H:F  the  18-19  (X* = 2.29,  P < 0.05  The  to  shows  at  1:1  i n t h e r a t e o f development  differences  f o r the S t r a i t of Georgia  than  the expected  S t r a i t of G e o r g i a samples  and  ratio  1.0  respectively). mm  16  the average,  mean  ratios  to  from  f o r a l l measured E«. p a c i f i c a  Inlet  e x c e p t a t about  different  and  Figure  Jervis  test,  to differences  size  catchability),  deviations  the  males  e a r l i e r age,  less  (about  12-  faster  in  f o r gonad graduate  resulting  in  50  o  • o v O  30  MEAN JERVIS INLET SAANICH INLET STRAIT of GEORGIA  BODY LENGTH mm  FIGURE 16. Changes i n s e x r a t i o (M : F) with JLL p a c i f i c a p o p u l a t i o n s d u r i n g 1975.  the  significantly  Except high  in Jervis after  abundance size  17 at  Inlet mm,  18  range sooner  lifespan the  lower sex r a t i o  at  this  males  19 mm  and/or size  i n t h e range  length  from  13-17  where male m o r t a l i t y was a p p a r e n t l y  the  to  body  their  which s u g g e s t s  spend  than  have  a  highest  that  they  for  mm. very  relative reach  this  greater  portion  of  their  do t h e f e m a l e s .  At s i z e s  over  19 mm  male m o r t a l i t y r a t e was a p p a r e n t l y  very  high  a s few s u r v i v e d  51 t o r e a c h 21 24  mm,  mm.  Some f e m a l e s , t h o u g h ,  probably  living  1-2  persisted  months  longer  until  about  22-  than  their  male  counterparts. There are other p o s s i b l e causes in  sex  ratio,  than  2.5  differences  Catch  vertical  curves during  study a r e a s . There  density  for  more c l o s e l y  21  t h e two  The  mm  the  presence  abundance o f t h e s e The  17  show  and  problem  . average  taken  by M i l l e r  by  SCOH  L-F net  nets i n a l l three  good a g r e e m e n t i n t h e s h a p e s  of  methods o f c a p t u r e ; t h e d i f f e r e n c e s i n to  the  vertical  stratification  represent the  m water column w h i l e t h e sound  by  larger  m/sec)  significance  the  scattering  layer  c o n c e n t r a t i o n s near  o f a shoulder r a t h e r than  taken  and  mortality.  i s , t h e SCOfi d e n s i t i e s  from  (3-4  of less  E^. p a c i f i c a  Inlet  represent l o c a l  females  avoidance.  due  i n t h e 0-150  determinations  for  variation  with s i z e  speed  A d u l t E. p a e i f i c a  i s generally  . That  concentration  and  high  are l i k e l y  Figure  1975  are p r i m a r i l y  E. p a e i f i c a  night.  in  hauls i n Saanich  curves  by  i n g r o w t h r a t e and  of J u v e n i l e  distributions  the  was  net hauls, c a t c h a b i l i t i e s  Mortality  the  such as d i f f e r e n c e s i n c a t c h a b i l i t y  s e x b u t a s most o f t h e s a m p l i n g Miller  f o r some o f  SCOP, amimals of  net  net was  average  Miller  net  of e u p h a u s i i d s the s u r f a c e  at  a peak f o r t h e  19-  suggests  that the  underestimated  selectivity  of  will  due  sampled to  net  be d i s c u s s e d  later.  The that  p o l y modal n a t u r e  different  periods  of the average of  time  catch  curves  are spent i n the  suggests  various  size  52  BODY LENGTH mm  FIGURE 17, C a t c h c u r v e s o f a l l E p a c i f i c a s a m p l e d d u r i n g 1975 by M i l l e r n e t (MNT) and by ~SCOR net" i n the Strait of Georgia region. A  increments, declining  more  in  rapidly.  indicates recruitment size  range  indicates  the a  modes  rising  less  numbers  are curve  i n t o t h e mode e x c e e d s m o r t a l i t y o v e r  that  from  left-hand  where  limb o f a c a t c h  ( c f R i c k e r , 1958)  graduation  and  w h i l e a descending  t h e mode a n d / o r  right-hand  mortality.  The  limb steep  negative high  slope  mortality  over  f o r t h e 20-24 mm  population; net s l o p e f o r the  the f i n a l  Comparison  mm  of  range  male E.. p a c i f i c a  the  male  and  12 and  mm  for this  male  size  earlier,  from  a  is  presented The  G6  age  o f changing l e s s time range  i n Figure  sample  than  in  net c a t c h c u r v e s s l o p e s suggests  i n the  earlier;  having  the  12-15  mm  females  approached  which  live  consistent  by  that range  accumulate  19-21  mm  6 of  their  mode. Figure  full  of s i z e - s e l e c t i v e  females  in  somewhat l o n g e r .  the  adult  mortality  same  cohort.  This  size  seguence  w i t h t h e i n t e r p r e t a t i o n o f t h e sex  of  ratios  earlier. of s i z e - s e l e c t i v e above.  Evidence  i s common t o most  stage  life  of  their  Bicker,1969) and  has which  mortality in  has  been  E.. p a c i f i c a fish  (Bicker,1969)  months when no s i g n i f i c a n t  ,  populations  is clearest  growth o c c u r s .  As  has  of l e n g t h ,  a normal  mortality  Jones  the average  Z,  s i z e of  is  a  animals  for  this  at  some  (1958,  in  which  i s not  within  which  positive  linear  length d i s t r i b u t i o n rate,  invoked  i n the winter  shown, i n a y e a r - c l a s s o f a n i m a l s  instantaneous  function  net  to  14.,  phenomenon, which  the  due  t h e m a l e s a p p a r e n t l y d i e at a s m a l l e r maximum  times  growing  Miller  experience a high rate  factor  several  mm  E.. p a c i f i c a  the females  events  16-19  female  mode b e f o r e g r a d u a t i n g to t h e  and  younger  Conseguently  members o f t h e M i l l e r  c o n t e n t i o n i s s e e n i n c u r v e s 5 and  c u r v e s G5  The  than  t e n d t o spend  i n the  14-16  Support  is likely  i n t h e SCOB n e t sample p o p u l a t i o n .  u s i n g t h e above i n t e r p r e t a t i o n s  in  increments  a v o i d a n c e p r o b a b l y c o n t r i b u t e s t o t h e change  18-22  but accumulate  size  in  the  year-  class  declines  with  time, but the length frequency  i n t h e y e a r - c l a s s remains not  change. B i c k e r (1969) h a s p r o p o s e d  selection(r)  or s e l e c t i v i t y r  where  d = decrease  difference  standard the  difference  the  smaller half  the  best  present early  decline April  i n average  rate  during t h i s  half  body  values  of  the  Saanich  Inlet  January  and H a r c h ,  approximately  deviations  calculations  i s observed  mean body l e n g t h s from  normal  rate  length frequency  o f r have been  in  in  population during where  a  general  between J a n u a r y and  February  chosen  (cf Fiqures  =  between  mortality  calculate  i n d e x , r , f o r E,. p a e i f i c a  were  s  i s egual t o  g r o w t h i n l e n g t h r e s u m e s . To  selectivity  1975  interval,  of length;  size-selective  the Saanich I n l e t  length  a = the  of the age-group.  months o f 1974 and 1975 ( F i g u r e 10) mean  interval;  instantaneous mortality  examples o f apparent a r e from  of  1.349d/s  i n s i z e by one u n i t  and t h e l a r g e r  study  in  intensity  i n length. T h i s s e l e c t i v i t y index  before s i g n i f i c a n t  standard  1. 349as =  differ  does  d e f i n e d as :  i n mean l e n g t h i n one t i m e  that  deviation  The  =  index  deviation  an i n d e x o f  i n instantaneous mortality  between a n i m a l s  the  n o r m a l and t h e s t a n d a r d  distribution  and A p r i l  paired  distributions  sexes i n 1974 and  examples with  8 and 9 ) . The r e s u l t s  recorded i n Table  8.  of  similar of the  55 TABLE 8. V a l u e s o f s e l e c t i v i t y i n d e x , r , f o r E. p a c i f i c a sexes from Saanich Inlet f o r p e r i o d s o f no q r o w t h i n 1974 and 1975. Date  Mean ±  Sex  d (rom/roo. 1  20Feb.74 3 Apr.74  M M  12.0 11.5  +  20Feb.74 3Apr.7U  F F  12.1 11.7  ± 0. 96  20Jan.75 24Mar.75  M M  20Jan.75 24Mar.75  F F  The  0. 94 ± 0.83  36  0.53  0.44  1.08  0. 29  0.38  0.28  14.9 14.1  ± 1. 21 ± 1.08  0.39  0.45  0.29  15.2 14.2  ± 1. 13 ± 1.37  0.48  0. 56  0.25  +  0.  above v a l u e s o f r show no s i q n i f i c a n t  (t = 0.15, P > 0 . 4 0 ) ;  they  indicate  months o f e a c h y e a r t h e l a r q e r averaqe  mortality  which a f f e c t e d of a l i n e a r  observed averaqe  loqarithraic  July  for  adult  mortality of  m o r t a l i t y r a t e with  euphausiids,  then  would r e a d i l y  males  and  an  that  assumption lenqth  the  account  consequently  hiqher f o r the  the  of  E.. p a c i f i c a  cohorts  cohorts  (eq.  Fiqure  1975 c o h o r t h a d an a v e r a q e and  was  estimated  p l o t s o f t h e month-to-month p o p u l a t i o n d e n s i t i e s  respective  sprinq  winter  low  M . F sex r a t i o .  Survival  the  of the cohort. I f the  o f male E. p a c i f i c a  hiqher  the  of the cohort experienced  increase i n instantaneous  rates  durinq  by s e x  r a t e t h a t was q r e a t e r by a b o u t 0.5 t h a n  the shorter half  is at a l l realistic growth  half  that  difference  February,  accordinq  a b u n d a n c e s from  SCOR v e r t i c a l  period  qrowth i n J u l y  of r a p i d  18). I n Saanich  survival to linear  hauls and  of  76%/mo  from in  I n l e t the between  r e g r e s s i o n o f monthly  ( F i q u r e 18,A). F o l l o w i n q t h e Auqust,  when  survival  of  j u v e n i l e s and immature a d u l t s =  .89), t h e i r  (7-12 mm)  percent s u r v i v o r s h i p  was o n l y  increased  about  t o 56%/mo between  a u g u s t and O c t o b e r , t h e n  t o about  maturity  and F e b r u a r y . From M i l l e r  between O c t o b e r  of abundance, 35%/mo about  juvenile  between  July  (7-12 mm) and A u g u s t .  55%/mo d u r i n g J u n e  and J u l y  For t h e Saanich I n l e t two of  sexes could  spring  be d i s t i n g u i s h e d  19-22 mm f e m a l e s between J u l y  68%/mo f o r t h e p e r i o d  survival  was  for July  about  during  component o f t h i s contrast, in  (Figure  mode was s t i l l  mature  the Strait  Inlet. of the  1975. The mean s u r v i v a l  and August  from  Miller  (Z=.559 ± . 1 0 1 ) . regression  18,B).  was  males was  1974 c o h o r t , m o r t a l i t y  t o F e b r u a r y from  65Vmo  Inlet  o f 14-18 mm  i n Jervis  of early  net estimates  i n Saanich  Survival  n e t a b u n d a n c e s was 57.4 + 5.1%/mo survival  41%/mo (Z  and SCOB  The  average  o f SCOB a b u n d a n c e s  By F e b r u a r y , o n l y t h e 19 mm  sampled  by  the  SCOB  n e t . In  f e m a l e s o f 18-24 mm were t a k e n by M i l l e r  of Georgia  and  Jervis  Inlet  during  nets  the  fall;  r e p r e s e n t a t i v e segments o f s u r v i v a l c u r v e s f o r t h e s e c o h o r t s a r e given  in  50%/mo  Figure  18, D and E. S u r v i v a l o f t h e o l d e r f e m a l e s was  (Z = .692) between J u l y  Georgia  and  45.7  December i n J e r v i s  Male s u r v i v a l but  the  and  August  i n Saanich I n l e t between  was l o w e r  estimates  cruises, rate  from  The e s t i m a t e o f s u r v i v a l  n e t abundances was 25%/mo  steady s u r v i v a l  in  the  Strait  of  Inlet,  disparity  Miller  October  ± 2.7%/mo (Z = .783 ± .059) between J u n e and  c a p t u r e was g r e a t e r . from  and  than  for  t h e two methods o f o f 17-21 mm  62%/mo  (Z  =  males  (Z = 1.386) between  b u t t h e SCOB n e t abundances y i e l d e d a of  females  .476)  f o r this  July  fairly cohort  57 between J u l y  and F e b r u a r y  mode i n S a a n i c h I n l e t  (Figure  18, C ) . The c o r r e s p o n d i n g  had a s u r v i v a l r a t e  1. 555 ± .559) between J u n e and  December  ESTIMATED  AGE  o f 21.5 ± 5.5%/mo (Figure  18,  male (Z =  G).  The  months  FIGDBE 18. Examples o f s u r v i v a l c u r v e s f o r E p a e i f i c a c o h o r t s . Age of c o h o r t s determined as (12Y • estimated age increment) where y=0 f o r f i r s t y e a r c o h o r t s and y= 1 f o r second year c o h o r t s . A  survival  of  similar  males  3251/mo (Z = 1.15) between J u l y appears  that  of  21-23  the  i n t h e S t r a i t o f G e o r g i a was and O c t o b e r  (Figure  t h e SCOR n e t h a u l s u n d e r r e p r e s e n t e d  underestimations  mm  male of  the  and  female  mortality  E. p a e i f i c a  18,  about  F) .  It  t h e abundance leading  to  o f t h e modes a s a w h o l e , a s  58 the  catch curves  in Figure  juvenile  and  densities  seem t o a g r e e  becomes  a  euphausiids  the  adult  survival  reasonably factor  in  over  18  with  about  noted  over  possibility  a  18 mm  mm  similar taken  of net  by  by  Net  estimates and  vertically  of net  likely  sampling  hauled  of  nets.  d e c l i n e i n abundance o f  vertically by  Miller  avoidance  representative  rapid  avoidance  The  SCOH  well.  significant  Brinton(1976) E. p a e i f i c a  early  17 a l s o i n d i c a t e .  hauled  CalCOFI  nets;  l a r g e i n d i v i d u a l s was  also  suggested. To  summarize t h e  Strait  of  presented those data  Georgia  the  egg-to-larvae  s u p p l i e d by  survival  of  begins  10  of the curve  and  cited  o f E,. p a e i f i c a  hypothetical survival  and  May.  i n Table  survival  rates  in  The  expressed  o f an E. The 9.  curves pacifjca  r a t e s used  in  the  curves  are  include  larvae-to-juvenile estimated  females  eggs i n e a r l y are  survival  F u l t o n e t a l . . (1969).  males 7  on  region,  i n F i g u r e 19;  for  as  results  follow cohort  from the which  construction  59 TABLE 9. R e p r e s e n t a t i v e s u r v i v a l rates f o rstages of E pacifica i n t h e S t r a i t o f G e o r g i a r e g i o n used i n c o n s t r u c t i o n o f t h e h y p o t h e t i c a l s u r v i v a l c u r v e s i n F i g u r e 19. A  Stage  Size (mm)  Age (mo)  Survival r a t e %/mo  Mortality Z= - l n (s)  Egg Larval N t o F3 Furcilia F3 t o J Juvenile  .40 1-4.5  0 1  5.7 ± 1.5 42.0 ± 1.7  2.86 ± .28 .86 8 ± .41  4. 6-8  2.7  40.8 ± 5.6  .897 ± .14  8-12  4  56. 3  .574  12-14  5. 5  67.8  . 389  14-18  10  Numbers surviving 1.0 x 107 1.34  x 105  4. 08 x 10* 1.72 x 10*  Small adult Medium adult  F 67.8  ,389  M 55.5  .588  2.99 x 103 F 4.28 x 10«  18-24  Large adult  M 32. 3 F 43. ,  18  1.58 x 102  M .559 ± . 10 F 1.13 M . 825 F 1. 15 M  F 57.4 ± 2.9  15  M 31.7  8.00 x 102 5.32 1. 54 x 10i 0.53  20  Linear population rates  regression on  of the  natural  age y i e l d s t h e f o l l o w i n g  from 4.6 mm l a r v a e  numbers, before  51.3I/mo  reaching  hypothetical  virtual  cohort  persist for  about  elimination.  agree c l o s e l y with  surviving  E.. p a c i f i c a (Z  A f t e r 20 months t h e m a l e s have d e c l i n e d but t h e females  of  mean l i f e - s p a n s u r v i v a l  i n the hypothetical  60.7%/mo (Z = ,500) f o r f e m a l e s a n d males.  logarithm  The  =  cohort;  .668) f o r  to i n s i g n i f i c a n t  three  more  months  life-spans  o fthe  the e s t i m a t e s from  f r e g u e n c y d i s t r i b u t i o n a n a l y s i s which were p r e s e n t e d  length  earlier.  60  500000  lOOOOOf-  4  6  8  IO  12  14  16  18  20 22  24 26  t (age) months  FIGURE 19. H y p o t h e t i c a l s u r v i v a l c u r v e s f o r E^. fiacltica i n t h e S t r a i t o f G e o r g i a r e g i o n . F o r e x p l a n a t i o n s e e t e x t . Symbols i n d i c a t e immatures ( i ) , f e m a l e s (a) and m a l e s ( e ) .  61 2.6 D i s c u s s i o n . In t h e S t r a i t strong  recruitment  associated in  with  a l l three  chlorophyll-a the the  of Georgia  successful  high  levels  of  areas were  fall  present.  larvae  May  i n Saanich  which  was  also  during  1966 a s m e n t i o n e d  evidence southern along  eggs with  that  heaviest  California  that c o a s t . During  t h e main  September, p u l s e s o f e u p h a u s i i d in  the  southern  were e n c o u n t e r e d lower and  i n nearshore  surface temperatures  while by  a  phytoplankton  high  bloom i n S a a n i c h  Brinton{1976)  has  spawning  Inlet  presented  activity  off  s p r i n g - e a r l y summer  upwelling  upwelling  April  larval  period,  recruitment  were  observed areas o f f  o f f O r e g o n most e u p h a u s i i d upwelling  areas  and h i g h p r i m a r y  to  larvae  characterized  productivity  by  (Smiles  Pearcy,1971).  In  contrast  to  Oregon and s o u t h e r n Ji  Likewise,  provided  bolstered  n u t r i e n t - e n r i c h e d s u r f a c e waters i n nearshore California.  high  the coincidence of a  E^ g a c i f i c a  c o i n c i d e s with  when  Inlets,  a  be  November.  a diatom  earlier.  to  occurred  cohorts  b e n e f i t t e d from  P a r s o n s e t a l . . (1967) a l s o n o t e d of euphausiid  appears  and J e r v i s  bloom i n September and warm w e a t h e r i n t o  biomass  subsequent  and/or June  The s p r i n g  population  cohort  and  abundance. Spawning  during  recruitment Georgia  spawning  E. p a e i f i c a  phytoplankton  study  strongest Strait  of  region,  paeifica  October.  the  year-round  California,  successful,  i n the Strait  larvae are recruited  The s p r i n g a n d e a r l y but  fall  cohorts  recruitment  of l a r v a e o f f  of Georgia  o n l y i n the p e r i o d from  summer c o h o r t s a r e g e n e r a l l y may a l s o c o n t r i b u t e  region May t o most  significantly  62  to  the  adult  cohorts  population.  with  latter  highest  half  California  of  the  In  survival year;  (Brinton,1976)  ( S m i l e s and  the  southern  are  June and  populations,  g e n e r a l l y produced  to  December  October  off  cohorts  in  the  Strait  of  from  l e n g t h frequency  described  von  Bertalanffy(1938)  eguation  yield  by  by  the  application and  s p r i n g and reaches  in  Holt(1957).,  summer, growth  a  winter two  body s i z e ,  resulting  adolescents  As  resume growth t o w a r d  their  E.. p a c i f i c a  commonly  up"  of adolescent euphausiids  inferred  appeared several  t o be  The  sufficient  reaches  also  growth o f s e x e s several direct  higher for E  differences  to distinguish  equations  for  of  growth  during  the  body  slow  length  down i n  early winter  different-aged  t  in  the  first  two  adult size  adolescence  end  adults in  the  southern  availability  indirect  pacifica  von  Off  within  "piling-  occurs(Brinton,1976).  and  the  size. full  food  after  growth r a t e s n e a r  cohorts of f i r s t - y e a r  studied.  growth  by  method  n e a r l y t h e same  adult  during p e r i o d s of lower  indicated  the  of groups o f  maximum  y e a r , but  Differential  has  until  may  attain  which  mode. I n t h e f o l l o w i n g s p r i n g , s u r v i v o r s  one  First,  growth  in "piling-up"  one  rapid  i n the f a l l  o r more c o h o r t s may  into  California,  slows  Georgia  d i s t r i b u t i o n s i s well  estimation  Following  maximum.  adulthood,  is  southern  t o December o f f O r e g o n  populations inferred  Beverton  i n the  Pearcy,1971).  Growth o f E i p a c i f i c a  further  the  (11-12  types of  o f the  evidence.  growing  season  males t h a n f o r f e m a l e s the  three  season  growth  Secondly,  in  populations were  Bertalanffy constants sexes.  ram)  of  the  not the von  63 Bertalanffy vary  constant,  significantly  completion ratio  range  suggest  mortality  exceeded  18  mm  mortality  size  than mm  (Z =  mm  E.  and  considered have  this  as t h e  curves  mm  body  as l a r g e  was  2-3  than  earlier  and  (over  thought  t o be  size-  in  the  lower  appeared  some a c h i e v e d  then  the  That  mm  same  16-18  o f the  If  catch  females; with  females  the  appear  increments  as a  possible  r a t i o i n favour of females  t o be s m a l l e r t h a n with  mm  i n age  Brinton(1976)  population o f f southern  the c a s e  i n the  t o males a t s u c c e s s i v e  r e c o g n i z e d by  where  females.  14-16  growing  though,  the s i z e  mm  males c o r r e s p o n d  slower  ages,  before the  males o f  14-  have o f t e n been  have r e a c h e d  are contemporaries 19  longer i n the  males, t h e y  18 mm)  f o r t h e b i a s of t h e sex  tend  size  Males  1.13)  they  months and  California.  o t h e r a u t h o r s have g e n e r a l l y c o n s i d e r e d t h a t  I*. p a e i f i c a  mm  higher  (Z =  sex  curves  females.  adults;  males of the  abundant r e l a t i v e  the E i p a e i f i c a  is  17)  length  explantion  and  sex;  occurs  females.  increasingly of  larger  the case,  (Figure  catch  experienced  tend t o remain  classes  d w i n d l i n g number o f >  18-20  ± .10)  though,  the  16-19  growing  high m o r t a l i t y  Females,  females  mm  mortality  i s indeed  to  r a t e s of  in  and  did  mm.  paeifica 19-21  changes  experience a  slower  t h e l a r g e m a l e s by  a p p a r e n t l y matured  increased  the  due  .559  body l e n g t h s o f 23-24 Since  the  growth  different  ( F i g u r e 16)  conseguently  range.  rates  of  males a d v a n c e i n t o t h e  and  22  t o have o u t l i v e d  16  season  indicating  body l e n g t h  that  before females  rarely over  between s e x e s ,  increasing  17)  selective  f o r t h e second  of t h e growth p a t t e r n . T h i r d l y ,  with  (Figure  K,  females  Nemoto(1975)  adult  males  of  o f t h e same a g e ,  Meganjctiphanes  in  norvegica  as  (eg.  Mauchline,1960) .  Other  sexes  studies  in  their  euphausiids least  (eg.  of  Smiles  i n E± p a c i f i c a  and  r a t e s based  18  Euphausiids over  the  SCOR  pattern tend  this  samples,  e s p e c i a l l y f o r males. mortality  with each  size  From t h e M i l l e r  E.. p a c i f i c a  (4.6-8 mm)  to j u v e n i l e  (12-14  mm).  survival  (8-12 mm) early  females 18-24  declines mm  as they  range.  population after  Large 19-20  reach  survival  mimic o b s e r v e d  by a b o u t  and  by  (13  Brinton(1976)  mm).  observed  18 mm,  from  mortality  final  population  rates,  the  following  Survival larval  juvenile  to  rates phase small  growth o f males  of males. S u r v i v a l o f  sexual  maturation  in the  d i s a p p e a r from  t h e sampled  off  California,  that  after  4%/mo  with l i f e  length-biomass  increased  to  n e t e s t i m a t e s and SCOR n e t  11-12S/mo  southern  the  whereas i n a h y p o t h e t i c a l a g e - f r e q u e n c y to  up  mm.  observed  dropped  SCOP, and  other f o r s i z e s  i s suggested.  males r a p i d l y  For t h e E. p a c i f i c a Brinton(1976)  differential  o f t h e sexes.  maturity, faster  leads to a higher s i z e - s e l e c t i v e  of  Matthews,1973) . A t  10-15 % w i t h c h a n g e s f r o m  After  growth  i n a bias to mortality  e s t i m a t e s f o r e u p h a u s i i d s under in  between  a p p e a r t o be u n d e r - r e p r e s e n t e d  resulting  t o i n c r e a s e by a b o u t  adult  Pearcy,1971;  and  on abundance e s t i m a t e s from  net hauls are c o n s i s t e n t  in  structure  merits separate treatment  Miller mm,  size  populations, the evidence f o r  growth and m o r t a l i t y Mortality  w o r k e r s have n o t d i f f e r e n t i a t e d  larval  history  phase, phase  a t p h a s e c h a n g e s up t o e a r l y  and d e r i v e d s u r v i v a l  changes  distribution constructed  d i s t r i b u t i o n s t h e mean  attributed  mean  the  survival adulthood  difference  r a t e s t o uneveness i n r e a l  between growth  65 rates. The part that  changes i n s u r v i v a l  due  to  as the  rapidly  size-selective  larger  than  a  effects  larger of  decrease  effect  patterns  between  predation)  are l i k e l y  Although  on  a was  Inlet  al^_ , (1968). larval juvenile  in  a  points out  disappear  more  mortality rate  i f  other  no  In a d d i t i o n t o t h e  changes thus  factors  in  behaviour  succeptibility  to  involved.  sampling  program  not undertaken  to  in this  and a d u l t e u p h a u s i i d s  predation  on  s t u d y , some i n f o r m a t i o n juvenile  fish  in  a d a t a r e p o r t by B a r r a c l o u g h e t  f o r consumption  presented  examine  by l a r v a l a n d  i s a v a i l a b l e from  are  (and  in  average  rate.  mortality,  life-phases  The r e s u l t s  stages  p h a s e s may be  cohort  with time,  mortality  a b o u t p r e d a t i o n on e u p h a u s i i d s Saanich  history  m o r t a l i t y . Sicker(1969)  individuals  size-selective  E. p a c j f i c a  life  t h e s m a l l ones, t h e o v e r a l l  of t h e s u r v i v o r s w i l l have  with  in  of euphausiid  Table  10a w h i l e  i s summarized  eggs  and  p r e d a t i o n on  i n Table  10b.  66  TABLE  10a, Summary o f c o n s u m p t i o n o f e u p h a u s i i d e g g s and larvae by j u v e n i l e f i s h i n S a a n i c h I n l e t d u r i n g A p r i l - J u l y , 1 S 6 8 . ( d a t a a r e from B a r r a c l o u g h e t a l . ,1968),  Fish  Number  Mean (mm) forklength  0_. g o r b u s c h a 304 p7 k e t a ~ 220 0. n e r k a 83 G. a c u l e a t u s 118 £i pa11asii 22 0._ k i s u t c h 5 Ejj. mordax 5 P leu ronectidae 3 Sebastodes sp^ 6 l i signatus 7 As. h e x a g t e r u s 3 lis. a l e u t e n s i s 3 H. s t e l l e r i 3  TABLE  90. 2 88. 1 113.7 77. 8 104. 2 127. 6 100.2 16.3 10.3 20. 20. 20.7 55.  739.9 171.0 43 6.1 194.3 166.6 9.8 32.0 7.7 1.0 2.3 6.0 20.7 17.0  40. 45. 85. 8. 0. 0.  stage eaten. Others  1 6 2 5 3 2  0.3  10 b. Summary o f p r e d a t i o n by j u v e n i l e f i s h on j u v e n i l e and a d u l t e u p h a u s i i d s i n S a a n i c h inlet during April-July 1968. ( d a t a from B a r r a c l o u g h e t a l , , 1968) .  Fish  Number  Mean(mm) forklenqth  175.0 141. 3 92.3 73.9 97.0 101. 1 128.7 154.0 62. 3  s. g a i f d n e r i i 50 kisutch 63 keta 84 aculeatus 56 gorbuscha 43 nerka 22 c. p a l l a s i i 3 2 I i productus 4 Si stelleri Oi Oi G7 o. o.  The consumed and  Mean no. o f each Eggs F u r c i l i a  fish  young about  other  10  with  times  larval  Mean no.  5.1-8.  0.02 0.02 1.8  euphausiids in  o f size(mm)  eaten  8. 1-15.  > 15.  19.4 7. 2 2. 4 2.7 1.5 2. 3 14.7 14. 5 2.0  0.36 0.02 0.06 0.04 0. 12  t h e i r stomach  more e u p h a u s i i d e g g s / f i s h t h a n  s t a g e s . J u v e n i l e salmon,  furcilia  (Oncorhynchus  spp^ii  threespine stickleback, Gasterosteus aculeatus; P a c i f i c  herring,  Clupea  had  pallasii^  highest the  fish  average taken  and  the  anchovy,  Engraulis  consumption o f the e a r l y i n the  two-boat  trawl.  mordax  x  the  e u p h a u s i i d s t a g e s among  Predation euphausiids, 8.1-15  the  juvenile Ii  predominantly  mm  size  gairdnerii, were  by  most  on  paeifica  range.  and s a l m o n ,  fish  ,  Juvenile  was  spp  Although  few were t a k e n  young h e r r i n g and P a c i f i c  hake, M e r l u c c i u s  be  of  predators  Herlinveaux(1965 of  juvenile  appeared Inlet of some Ii  doqfish,  Other  fall  day  (W.  productus.  of  contained  layer  Stomach  of  i n the S t r a i t  pileus  x  which becomes h i g h l y  near  Saanich contents  zooplankton;  predators  Greve,  for  in  w h i t i n q , r o c k f i s h and  species  euphausiids  to  quantities  eaten.  of  appear  hake and h e r r i n q which  soundscatterinq  several  catches,  B a r r a c l o u g h and  large  i n v e r t e b r a t e zooplankton.  and i s c a p a b l e  from l i v i n g  of Georgia  t h e ctenophore,  abundant  o f c a p t u r i n g many e u p h a u s i i d  in  summer  l a r v a e each  p e r s o n a l communication) . Presumably t h e change the s u r f a c e as l a r v a e t o m i g r a t i n g  to  greater  t h e d a y l i g h t h o u r s a s j u v e n i l e s and a d u l t s h e l p s t o  r e d u c e p r e d a t i o n by s u r f a c e - d w e l l i n g rely  i n the trawl  include carnivorous zooplankters, notably  and  Salmo  G._ a c c u l e a t u s  was t h e p r e d o m i n a n t s p e c i e s  flegrpbrachia  depths  a  suckleyi,  j u v e n i l e and a d u l t d o q f i s h , hake,  paeifica  region  Squalus  t o be f o l l o w i n q  herrinq  adult  i n the  trout,  and  i X  young e u p h a u s i i d s .  MS) r e p o r t e d t h e p r e s e n c e  which c o n t a i n e d  the  heaviest  steelhead  pneorhynchus  and  f r e g u e n t l y c a u g h t c o n s u m e r s o f t h e j u v e n i l e and  adult euphausiids.  important  juvenile  on v i s u a l  d e t e c t i o n o f prey.  larger euphausiids  may  predators.  Working  euphausiids  are their  also  help  against larger  enemies  and  The i n c r e a s e d in  improved  those  mobility of the  escaping  from  survival  t a r g e t s i z e s and d e n s e  which p r e d a t o r s c a n d e t e c t , a c o u s t i c a l l y  which  i n t h e case  of  certain larger  aggregations of  baleen  68 whales by  ( e g . Beamish a n d M i t c h e l l ,  hake, h e r r i n g  The  life  and o t h e r  span  of E  A  southerly  life-span months,  paeifica that  described for populations  r e g i o n s o f t h e e a s t e r n North  females  living  about  males. I n c o n t r a s t , E. p a e i f i c a  from  was between  Oregon, s o u t h e r n  o f about  and  Pearcy,1971;  H u l s i z e r , M S ) . The  between  the  availability Georgia  temperatures length  of food, e s p e c i a l l y  during  compared  appears  population,  late  t o halt  fall  and  more  phytoplankton  o f Georgia.  F i g u r e 20  curves  f o r E. p a e i f i c a  Pacific  with curve  Inlet  presented  from  where is  compares four  Figure  difference  to  t h e low  i n the S t r a i t o f to  lower  water  Strait  of  Georgia  water  temperatures  and the  southern  the  generalized  growth  o t h e r r e g i o n s o f t h e North  10. A l t h o u g h  cohort  from  the average  t o 0.065 mm/day f o r E. p a e i f i c a  California  ( S m i l e s and P e a r c y , 1 9 7 1 ;  maximum r a t e s f o r j u v e n i l e  regions;  Saanich  Inlet  growth  are  more a b u n d a n t t h a n i n t h e  Saanich life-span  growth f o r c o h o r t s i n t h e S t r a i t o f G e o r g i a r e g i o n i s o n l y 0.038 mm/day compared  in  rate during winter o f f  D-E o f t h e 1974 s p r i n g in  (Smiles  r e g i o n s . Whereas growth i n  a reduced  California,  Strait  and  during winter i n the at  than  California  or less  attributed  winter  t o the southern  i t continues  and  be  22  p o p u l a t i o n s and t h e i r  phytoplankton,  Oregon a n d s o u t h e r n uniform  one y e a r  S t r a i t o f Georgia  southern counterparts can probably  19 and  2 o r 3 months l o n g e r  Puget Sound had l i f e - s p a n s Brinton,1976;  in  P a c i f i c Ocean. The  and  life-span  ways  populations i n the S t r a i t o f  o f cohorts i n t h e present study with  i n other  fishes.  Georgia r e g i o n i s l o n g e r than more  1971) and l i k e l y  o f f Oregon  Brinton,1976),  are similar  j u v e n i l e s averaged  about  for  these  0.094 mm/day between  69  NORTHWEST. PACIFIC 1 (NEMOTO) -  OREGON  t  4  6 8 10 MONTHS  FIGURE 20. R e p r e s e n t a t i v e growth c u r v e s f o r E fiacifica from t h e S t r a i t o f G e o r g i a and o t h e r r e g i o n s o f t h e P a c i f i c . (After B r i n t o n , 1976; S m i l e s and P e a r c e y , 1971). t  May and August  while  (Smiles  and  reported  maximum  populations of  of  j u v e n i l e s i n c r e a s e d by 0.095  mm/day  P e a r c y , 1971). B r i n t o n (1976) and H u l s i z e r have growth  r a t e s o f about  0.095  mm/day  d u r i n g t h e s p r i n g and summer. These  t h e maximum  estimate  Oregon  growth maximum  rate growth  exceed in  field  L a s k e r * s (1966)  in  also field  estimates laboratory  juvenile  E^ p a c i f i c . a  paeifica  in  (C.038  mm/day).  The Georgia  average growth r a t e o f E region  appeared  x  t o be h i g h e r  the  and t h e l i f e  Strait  span  of  shorter  70 than  for E  pacifica  A  Nemoto(1957) the  populations  considered  that  Aleutian Islands reached  year  as d i d the  Jervis  populations  may  live  E  rapidly  in their  disappeared  in  in  the  sampled  in  frequency winter  mode  previous  at  8 mm  summer w h i l e  starting  its  year  and  old)  second 19  mm  and  spans of of at  a l l during  succeeding Atlantic  mm the  Mauchline,1960; rasehii  grows t o a b o u t 22 M a r r , 1962) .  E  on  the  and  A  and  The  grew  the  end  live  basis of  bimodal  more  of  up  two  to  The  during  thought  s p r i n g modes were a t  2  length  collections.  was  2  generally  pacifica  spring  mm  after  region  before  and  Neinoto's  mm  mode  euphausiid  s p e c i e s has  winter  have been f o u n d  then  season.  year,  the  to  12-13  be  mm  Examples  Matthews,1973;  Euphausia  and  their  with  a body  (1  final  from r e g i o n s  size  by life  length  slowly  or in  of the  not the  North  ( E i n a r s s o n , 1945;  Berkes,1976), Xiisanopoda  superba  in i t s f i r s t  species  to reach  noryegica and  summarized  growing o n l y  attaining  Meqanyctiphanes  mm  been  Several euphausiid  (Mauchline,1966)  (Einarsson,1945).  22  14-15  in their f i r s t  growing are  of  Nemoto's  first  Georgia  t o have h a t c h e d  Pearcy(1971).  22  of  considered  year.  2 o r more y e a r s  about  in their  of  (2 y e a r o l d ) .  Growth o f o t h e r Smiles  the  mm  attaining  that  of winter was  17-18  members  than  Okhotsk  distributions  south  population  years  of  o f f J a p a n and  Strait  year,  season  Ponomareva(1963) i n f e r r e d Sea  Pacific.  S t r a i t of G e o r g i a  years.  the  the  northwestern  spawning,  the  second  from  pacifica  f o r another  pacifica  the  a length of  Following  years.  t  E.  spring cohorts  Inlet.  in  acutifrons  , the A n t a r c t i c  year(Ruud,1932;  Thysanoessa  krill,  also  Bargmann,1945;  71 Few  authors  euphausiids that for  have  by  mathematical  to  combined  s e x e s was  expressions,  first  and  year  onwards.  the  Growth  February, mortality  one  second  developed  and  modification  of  but was  where L i s t h e c a r a p a c e  of  the  length of  two  first  observed  effect of of  raschii  = kl (L  ;  their  the year four  in  each  size-selective  year.  species, including  autocatalytic dL/dt  of  found  r e t a r d e d f o r about  that the  t h a t time  Thysanoessa the  the combination  Jorgensen  a g e n e r a l growth e g u a t i o n  growth o f s i x e u p h a u s i i d  noryegica  growth i n c a r a p a c e  mean growth was  possibly indicating  Matthews(1975)  growth  Matthews (1973)  November  cease,  growth a t  the  applying t o A p r i l t o October of for  "Negative"  exceeded  the  w e l l d e s c r i b e d by  d i d not  months i n w i n t e r .  describe  expressions.  f o r Meganyctiphanes n o r y e g i c a  empirical  the  attempted  to  and  describe  Meganyctiphanes eguation  is  a  value  of  model: - L) / L  m  l e n g t h and  m  L„, i s t h e  asymptotic  L. Variability maturity same  i n the  between  euphausiid  Einarssori,1945;  r a t e s o f d e v e l o p m e n t , growth and  geographically species  has  Nemoto, 1957;  Fisher,1969;  Matthews,1973).  availability  and  causes  such  for  separated  been  Regional  variability(Mauchline availability  earlier  in  E  Georgia  with  A  acknowledged  paeifica  o f f O r e g o n and  (eg.  in  and food  t o be  the  and  Fisher,1969).  of phytoplankton populations  southern  the  Mauchline  differences  temperature are considered  comparing  populations of  Ponomareva,1963;  Differences i n seasonal  those  widely  sexual  i n the  California.  principal  were  cited  Strait  of  Brinton(1976} during  E._ p a c i f i c a  in f i v e this  by  f  species  has  Pacific  been  where  f o r 0-10 m from  Brinton  (Sverdrup  life  In  winter  history  Table  11  of mean  Saanich Inlet(Herlinveaux,1962) f o r  e t a l . ,1942;  values  guoted  Anonymous,1963).  11. S u r f a c e {0-10 m) t e m p e r a t u r e s d u r i n g E^. p a c i f i c a »s main r e p r o d u c t i v e p e r i o d and d u r i n g w i n t e r i n s i x r e g i o n s of t h e North P a c i f i c .  legion  Spawning t i m e  Winter  10-13C{Aug.) 9-11C (Aug. ) 10-12C(Aug.) 9~13C(May) 10-14C(Sept.) 10-18C(June)  0C(Feb.) 0- l C ( F e b . ) 2-4C(Feb.) 6- 8C{Feb.) 9-11C(Feb.) 12-15C(Feb.)  Sea o f O k h o t s k O f f Kamchatka South of A l e u t i a n s S t r a i t o f Georgia O f f Oregon Off southern C a l i f o r n i a  Although distribution  Epacifica  Pacific,  i s  apparently  by low w i n t e r t e m p e r a t u r e s ,  reproduction  i s much n a r r o w e r ,  Ej. p a c i f i c a  phytoplankton  about  i s almost  main  reproductive  highest  activity  finished,  temperatures  phytoplankton E. p a c i f i c a  of  is  the  limited  the suitable  does n o t b e g i n t o spawn  bloom  not  range  until  June  much l a t e r  in  August  year.  abundance i s o f t e n h i g h i n  In April,  at  but  are just  into  necessary  o f spawning  as  suggested  a d u l t s on by  t h e range  from  9-13C  of temperature, phytoplankton  Ponomareva{1963).  main  May when (compare  a period of  may Off  the  Inlet,  the  surface temperatures  conditioning  than the  Saanich  generally begins i n e a r l y  range  after  9-13C,  activity  7). Besides a s u i t a b l e  for  region(Ponomareva,1963).  spawning  Figure  in  9-16C. I n t h e n o r t h w e s t e r n  o t h e r common e u p h a u s i i d s p e c i e s o f t h a t The  the  investigated.  temperatures  and d u r i n g  c o r r e s p o n d i n g p e r i o d s have been added t o t h e  TABLE  the  t h e s u r f a c e water  s main r e p r o d u c t i v e s e a s o n  areas o f the North  temperatures the  h a s summarized  also  be  Oregon and  southern summer  California temperatures  subsurface those  which  are  change  lowered  between by  winter  upwelling  w a t e r . Spawning happens i n a l l months o f t h e  regions  Farther south oxygen  there i s l i t t l e  although  usually  o f f mainland  concentrations  ( B r i n t o n , 1976) .  Mexico  i t occurs high  in periodic  temperatures  appear to l i m i t the range o f E  of year  cool in  pulses. and  A  and  low  pacifica  74 CHAPTER 3:  3.1  Length:Weight  To  convert  weight  or  that  the  mean  (GH)  mainly  inherent  of  weight  the  where  ( d i s t r i b u t i o n s or  regression  more  c a l c u l a t e s the v  length). line  (Teissier,1948). the  vertical  line.  slope =  and  sy  and  respectively; regression  of  between X and  b  of t h e  line  of  uniform  the  slope,  sx  are  the  is  regression X  due  to are  density  predictive  value the  of  the  value  of  regressions  the  eguation  (eg.  of  the  as -X)2  io.*  minimizes the  v,  (sy/sx) = ±  on  is  vX,  horizontal distance  Y  geometric  be  line  A l t e r n a t i v e l y , the  shown  variability  widely-used  Letting  f <k {Y - Y ) 2 / ^ ( X  This  v = ± where  ±  are  morphometric  Y = u + one  i s the  : w e i g h t r e l a t i o n s h i p and in  has  distributions  under-estimate  coefficient  regression  relationship  variability  open-ended  The  usually  c a r a p a c e v e r s u s body functional  (little  observations  extent).  length  corresponding  functional  regression  material  measurement) and  i n the  a  the  i n a l l s i t u a t i o n s where t h e  regressions  exponent  into  i s necessary. Bicker(1973)  form o f l i n e a r  in  indefinite  linear  the  and  data  distributions,  regression  concerned and  length-freguency  appropriate  e r r o r s of  PRODOCTION  Relationship.  biomass  between l e n g t h  BIOKASS AND  and  Y while d i s the  of  can  (b/r)  sum  be =  standard  ±  the  products  of  each  point  from  the  found  as  (b/d) °s  deviations  coefficient r  i s the  of  of  the  of  Y  and  X  predictive  correlation coefficient  regression  coefficient  of  the  predictive geometric  regression mean o f  reciprocal is  the  the  of t h e  same  recommend t h e  of  X  on  Y  (Bicker,1973).  p r e d i c t i v e regression of Y  predictive  on  r e g r e s s i o n o f X on  a s t h a t o f b,d  and  Thus v i s t h e  Y.  X The  r . R i c k e r ( l 9 7 3 ) and  f o l l o w i n g symmetrical  confidence  and  the  s i g n of  v  colleagues  limits  f o r the  GM  regression: v ± t f v* {1-r«)/(N-2) where N i s t h e sample s i z e  and  the  with  given confidence The  computed  level  length  and  21  male  mm  paeifica  , t h e GM  as  regression  2.98  o f W on InW  L  Thus, the limits  appear  = -4.70  found  overlap of the  for  i t s 95% In  to  t h e two  be  confidence  limits the  were  predictive  , the  GM  + 3.03  (InL); H =  exponent, 3.03  regression  was:  443.  was:  v,  and  ± 0.066. As  female confidence  a significant both  r = 0. 973.  + 2.92 (InL) ; r - 0.961.  t o be  male and  sexes;  For  376.  comparison,  • 2.90(lnL);  = -5.01  female L : W  were  1975.  was:  comparable p r e d i c t i v e r e g r e s s i o n InW  April,  10  was:  F o r t h e f e m a l e E. p a e i f i c a  The  i n March and  «-2.98(lnL) ; N =  0.059.  = -4.71  InW  form;  m e a s u r e m e n t s on s p e c i m e n s between  v and  ±  for  degrees o f freedom. ,  regression  = -4. 86  male L ; W e x p o n e n t ,  calculated  multiplier  B (InL),  length, collected  InW The  N-2  = lna •  length-weight  body  t i s the Student  : w e i g h t r e g r e s s i o n s of t h e  InW were b a s e d on  0-5  ]  its there limits  95%  i s considerable there  d i f f e r e n c e between L  exponents are  confidence  very c l o s e to  : W  does  not  exponents  3.0.  76 3.2 C a r a p a c e : B o d y  Another crustaceans relation  between  a  in  length  to  measure  i s bent and c a n n o t  length,  the  and body  ordinary  as  carapace  regression  has  included  converting  from  Carapace  lenqth  predictive  range For such  no  systematic  i n t h e sample; one l e n g t h  :  total  and  Strait  collected  Further from  predictive  comparisons  Saanich  Inlet  (AM) r e g r e s s i o n  or  total  when  a  order  given  carapace  h a s been  commonly  coefficient  tends  available length  or  to  lengths  conversions  the  to  recommended  for  another(Ricker,1973).  c o m p a r i s o n s were made on f o r m a l i n  pacifica  of Georgia,  than  properly) . In  i ti s therefore  male and f e m a l e  the  i s the  b i a s r e l a t e d t o t h e range o f  measurement  length  used  rather  for a  of routine  other  necessary  damaged  regression  preserved  F5)  is  and  (eg. S m i l e s and  be  length  be s t r a i g h t e n e d body  the  increases(Picker,1973).  lengths  i s best  length  i n these s i t u a t i o n s the r e g r e s s i o n  increase  1976,  euphausiids  M a t t h e w s , 1 9 7 3 ) . At t i m e s i t may  to p r e d i c t t h e c o r r e s p o n d i n g  GM  on  ( e g . when t h e t e l s o n o r r o s t r u m  specimen  used;  work  functional regression  carapace  convenient  length  Relationship  situation where  Pearcy,1971; more  Length  a d u l t s from Saanich in July  Inlet  1975 and F e b r u a r y  were made on f u r c i l i a  larvae  i n May 1975. The r e s u l t s a n a l y s i s are presented  (F1  to  o f t h e GM and i n Table  12.  77 TABLE 12. Summary o f r e s u l t s f o r r e g r e s s i o n o f body length on c a r a p a c e l e n g t h s f o r Ej_ p a c i f i c a from S a a n i c h I n l e t and t h e S t r a i t of Georgia. Stage  Sample Size  Type o f Regression  Intercept  Regression Coefficient  95% C . L . or r  28  GM AM  -0.72 -0.54  4.18 4.01  4.18 ± 0.39 r = 0.96  45  GM AM  0.59 0.93  3.38 3.30  3. 38 ± 0.19 r = 0.975  170  GM AM  0.88 1. 11  3.35 3.29  3. 35 ± .083 r = 0.981  Furcilia  Male Female  There furcilia  is  period  a notable  and t h e a d u l t  s e x e s do n o t d i f f e r total  length  confidence  c h a n g e i n body p r o p o r t i o n s  significantly  relation;  limits  condition.  there  with is  f o r the regression  3.3 A n n u a l and M o n t h l y Ej. p a c i f i c a The  mean a n n u a l  consistent (Figure at  21),  11 mm,  correspond  Local  16-17 to  mm  during  mode sizes; Inlet  contributes the l a t t e r and S a a n i c h  a  wide  overlap  i n t h e 95%  coefficients.  o f body  length  shows  and  peaks  19-20  body  length.  of the adult  periods,  energy  to  total  mature  growth  in  part  reproductive body  length  f o r reproductive  of Georgia,  biomass than  major  These  phase, t h e e a r l y  reguirements  In t h e S t r a i t  sizes are the Inlet.  mm  phase and t h e f u l l y  then.  more  1975 i n t h e t h r e e  fairly  occur  because  are higher  respect t o the carapace :  maxima i n t h e d i s t r i b u t i o n s g e n e r a l l y  p h a s e , r e s p e c t i v e l y . In t h e s e  processes  two  areas  the beginning  probably  the  study  o f t h e main r e p r o d u c t i v e  slows  adults,  Biomass D i s t r i b u t i o n s  b i o m a s s p e r mm  distributions  As  between t h e  the  19-20  do t h e 16-17 mm  contributors  in  Jervis  FIGURE 21. T o t a l mean b i o m a s s and mean biomass by 1 mm size c l a s s e s o f E^ p a e i f i c a p o p u l a t i o n s i n the S t r a i t o f G e o r g i a r e g i o n d u r i n g 1975.  The than  value  twice  of  mean  as h i g h i n J e r v i s  on t h e b a s i s o f M i l l e r value  i s  biomass f o r a l l s i z e  lower  as  Inlet  than  i n the S t r a i t  n e t (MNT) e s t i m a t e s . the  c l a s s e s was more  SCOR e s t i m a t e s  The  of Georgia  Saanich  Inlet  a r e f r o m a 150 m water  column. For  t h e p r o m i n e n t 11,16 and 19 ram s i z e c l a s s e s , t h e m o n t h l y  v a l u e s o f biomass combined  MNT  Jervis Inlet, in  are plotted  biomass  i n F i g u r e 22  estimates  t h e changes  and  from t h e S t r a i t  f o r a l l three s i z e  phase. T h e r e i s a g e n e r a l  A  B.  For the  o f G e o r g i a and  classes are usually  d e c l i n e i n biomass o f  these  sizes  79 A.  M N T BIOMASS JERVIS INLET STRAIT of GEORGIA  O I9mm  E O O  o \  o>  1  -I  Oiool  B.  UJ  1  !< o  I  1  _1  I l _  '  '  0-—O I 6 r  SCOR BIOMASS SAANICH INLET  F  M  A  M  I  -I I 197S  I A  l _ S  O  N  O  FIGURE 22. M o n t h l y b i o m a s s l e v e l s o f c o n s p i c u o u s E. p a e i f i c a d u r i n g 1975.  during  April  to  numbers o r grow October, leading  July  out  recruitment to rapid  as  the  o f . these into  size classes of  overwintered adults classes.  these  major  r i s e s i n t h e i r biomass.  From  dwindle i n  about  July  to  size classes  expands,  After October,  biomass  80 at  these  t o be  body l e n g t h s a g a i n  i n response to  recruitment Georgia  and  The classes out 19  Jervis  The  spring  and  16  mm  adults  at  size  11  into  11  important given.  mm  from  in  Saanich  as Inlet  strong  Strait  prominent  i n January  in  of  the  in  from  April  the  to  January the  new  August t o O c t o b e r .  recruitment  cohort  the  spring  as t h e  young  August.  again  On  recruitment  from  dropped  the  total  pacifica  t o the t r e n d s  In  the  swelled  the  biomass i n  the  Changes  Saanich  p e r i o d of  in  Inlet  i n the the  significant  of the  production  as t h e  population.  by  Strait  and  biomass  19  mm  of are  two also  i n c r e a s e i n biomass of  each o f  production  16  population  June t o November. C o n s e g u e n t l y ,  well  as  d i s p l a y e d c y c l e s of  fall  the  class.  23).  of  size  to March,  October  to J u l y , then  populations  chosen f o r e s t i m a t i o n  the  and  i n biomass d u r i n g  high  class  May  size  E v i d e n t l y , the  about  three  larger size classes during  (Figure  cohorts  populations  to a  show s i m i l a r i t i e s  of the Ii. p a c i f i c a is  mm  from  changes  classes  sharply  strongly recruited  autumn, r e c r u i t m e n t  three areas  the  shorter intervals;  advanced  Monthly  of  increased  rapidly  s h a r p l y from  biomass o f t h e  adults  c l a s s t e n d e d t o drop i n biomass from  hand, t h e  rose  of  appears  were more complex as c h a n g e s were o f t e n  steadily  rose  decline  cohort  Inlet  c o h o r t was  other  biomass  After declining  class  to J u l y , then  the  i n the  phase.  October.  growth  pattern  Inlet.  i n Saanich  size  rapid  above  j u v e n i l e s t h r o u g h o u t t h e summer i n t h e  trends  of mm  of  the  d e c l i n e s . The  of the  Georgia this the  region  period E.  was  pacifica  major c o h o r t s  in  81  1000  JERVIS TOTAL  ^.STRAIT O F . •••-.GEORGIA TOTAL  . • J.-  100]  SOfSPRING 74 .SAANICH  5 °  -l—-—i  10i  M  1  1  M  1  '  1  •  J 1975  J  •  L  FIGUBE 23. M o n t h l y c h a n g e s i n b i o m a s s f o r a l l s i z e c l a s s e s (7-23 mm) i n E . p a c i f i c a p o p u l a t i o n s and i n S a a n i c h I n l e t c o h o r t s d u r i n g 1975.  3.4  Production  o f E,. p a c i f i c a  Production elaborated including (cf. was  a  t h a t due  Ivlev,1945; used  mortality for  in  i s d e f i n e d h e r e as t h e t o t a l  (LeBlond and  production  group o f organisms i n a given to organisms which  Z  is  and P a r s o n s , 1 9 7 7 )  of g r o w t h  biomass  period of  during  the  time, period which  assumes e x p o n e n t i a l r a t e s o f  i n b i o m a s s . The  i n a given  the  died  of  Chapman, 1968) . The method o f c a l c u l a t i o n  appropriate  expression  period i s :  P = where  amount  (1 + Z/G)AB  instantaneous  mortality  rate  and  G i s the  82 observed such  r a t e o f i n c r e a s e i n b i o m a s s , B , between t i m e s  t  t,  that B(t)  = B(t )  exp (G f t - t  0  For each p o p u l a t i o n o r c o h o r t the  rate  ) 3 against time,t,  the  The  period.  increase rate,  ] ).  during the periods  slope  of  f o r each observed  the  resulting  i n biomass,G. C o r r e s p o n d i n g  2,  were  biomass, and  0  o f i n c r e a s e i n b i o m a s s , G, was d e t e r m i n e d  ln [ B(t)/B(t  calculated  B, was computed  initial  line  values  by  biomass  the  as d e s c r i b e d e a r l i e r .  between  the  in  Inlet  production expressed water  estimates  Strait  practical area.  SCOB  vertical  produced  body  hauls  o f 0.05 was u s e d  carbon  and J e r v i s I n l e t over  to convert  from  a  limited units  of these presented  were  sguare other  vertical  o f volume t o  range, units  of  published weight  Crisp,1975).  biomass e s t i m a t e s  also  meter  t o c o n v e r t grams wet  ( c f . Mullin,1969;  final  population,  hauls  under a  z  of Georgia  horizontal  c o h o r t s and t o t a l  day (mgC/m /day) f o r c o m p a r i s o n w i t h  v a l u e s . The f a c t o r grams  from  i n u n i t s o f carbon  per  mortality  biomass o b s e r v a t i o n s i n t h e p e r i o d . V a l u e s  13.,For t h e S a a n i c h  in  The c h a n g e i n  production estimates are  Table  plotting  i s the rate of  of  as t h e d i f f e r e n c e  indicated,  p a r a m e t e r s and t h e r e s u l t i n g  to  and  As t h e  were  from  i t was n o t of  surface  83 TABLE 13. I i paeifica  Production populations  Population or C o h o r t  Period lday_sjL  S t r a i t of Georgia  estimates and a s s o c i a t e d and c o h o r t s d u r i n g 1975.,  parameters f o r  /mo  G /mo  B g/103  Jun-N (143)  . 576  .268  24 2.3  Jervis Inlet  Jun-N (143)  . 693  .541  1364.  Saanich I . Total  Jul-N (105)  . 564  .442  175.6  3.81  26.8  Sp 75 Cohort  Jul-N (105)  .586  .477  162.8  3.45  24.4  Sp 74 Cohort  Jul-0 (77)  .559  .334  24.6  0.85  6.0  P r o d u c t i o n p e r 1000 a higher  standing  c o m p a r i s o n s ,, useful  in this  of p r o d u c t i o n p e r i o d (1/Z) ,  Bertalanffy  life  of  the  production  in Jervis of  P mgC/m*/da  Inlet  Georgia.  which had For  such  a v e r a g e b i o m a s s , P/B, i s more  estimates  alone. Table  assuming e x p o n e n t i a l  P/B  analysed  f o r the  differences  period,  expectancy  in Jervis  3  14 p r e s e n t s  : b i o m a s s r a t i o s and mean l i f e  and c o h o r t s  values  despite  m /da  mortality  a  expectancy and  von  g r o w t h m o d e l s ( c f . , A l i e n , 1 9 7 1 ) , f o r t h e E.. p a e i f i c a  populations the  production  unit  3  21.8  the S t r a i t  per  q/10  3  5.34  was h i g h e r  3  s t o c k than  production  than the  summary  in  P m  Inlet.  in  similarity  various populations average  E.. p a e i f i c a  i n Saanich  above. T h e r e i s  Inlet  biomass.  apparently  in  and c o h o r t s , During  has a s l i g h t l y  and t h e S t r a i t o f G e o r g i a  this longer than  84 TABLE 14. P r o d u c t i o n : b i o m a s s r a t i o s and mean l i f e expectancy f o r E. p a c i f i c a p o p u l a t i o n s and Saanich Inlet cohorts during 19757" Population or Cohort  Life Expectancy  P  B  a/103 1.7  S t r a i t of Georgia Jervis Inlet Saanich I, Total Sp 75 Sp  3.5  mo  q/10  3/da  5.34 21.8  1.4  74  m  . 026  9.5 8.8  1.8  3.81  157  . 024  1.7  3.45  123  .028  10.3  1.8  0.85  35  .025  9,0  i n the S t r a i t  of Georgia  Biomass c h a r t s o f t h e  and  taken  Biomass of  5 mm  size  F i g u r e s 24  Takahashi,  to  27.  i n B. C.  24)  shows  The  distribution  of  Jervis the  megazooplankton  During generally section  As o n l y d a y t i m e  Fraser  River,  there  fraction  lower, of the  especially  Strait  are  megazooplankton over  here  2 mm  are  (Parsons  represents  plankton nets  ( o v e r 2 g/m )  the  currently  the  i n the S t r a i t  3  end  sampling  of T e x a d a I s l a n d was  nighttime  done o f f t h e distribution  i s u n c e r t a i n f o r the e a r l y  June-July, l e v e l s  net  i n the M a r c h - A p r i l p e r i o d ( F i g u r e  a r e a s o f h i g h biomass  Inlet.  Miller  s u r v e y c r u i s e s i n 1975  Although  G e o r g i a o f f Nanaimo, o f f t h e n o r t h w e s t in  from  to i n c l u d e zooplankton  1973), t h e > 5 mm  and  Region  megazooplankton f o r commercial  used  Megazooplankton  fraction  during the zooplankton  considered  nettable  yr ~  837  Phytoplankton  generally  *  8.4  of  as  da -  3  .023  Distributions  presented  m  3  228  Spatial  samples  P/B  P/B  of  the  in Jervis  of Georgia  large Inlet  and mouth of  spring.  zooplankton and  of  in the  ( F i g u r e 25) . A r e a s  of  were  northern moderate  85  FIGURE 24. D i s t r i b u t i o n o f wet b i o m a s s ( > 5 mm) i n t h e 107 kHz sound Harch-April 1975.  {g/m | o f m e g a z o o p l a n k t o n scattering layer during 3  FIGURE 25. D i s t r i b u t i o n o f wet biomass { > 5 mm) i n t h e 107 kHz sound J u n e - J u l y 1975.  (q/m ) o f m e q a z o o p l a n k t o n scatterinq layer durinq 3  87 biomass g/m )  (1-2  G e o r g i a and Saanich For spaced  by  Inlet  only  ( F i g u r e 2 6 ) . The  over  be  (July).  higher than  had  distribution  were to  biomass  but  found Saanich i n the  truncatum,  of  later. cruises  were little  in  in Jervis  of Georgia south of sampling.  the Inlet  Nanaimo  High biomass  levels  much l o w e r c o n c e n t r a t i o n s i n t h e Haro S t r a i t Inlet.  latter rather  Over  and  80%  a r e a s was  of  the  contributed  2 g/m  and  of  the  Strait  in Jervis Inlet  concentrations of  sampling  and  presents  an  corresponding cruise.  from  o f Georgia  of G e o r g i a from 1-2  g/m , 3  continuous  example  of  by  than e u p h a u s i i d s . biomass d e n s i t i e s  were w i d e s p r e a d  of  Swanson  In t h e October-November s u r v e y p e r i o d , 3  of  biomass  involved  o f G e o r g i a and  by d a y t i m e Inlet  coverage  (2-4  Strait  for the previous period  the S t r a i t  the F r a s e r River i n the S t r a i t area  of the  the survey  weeks so s t a t i o n  area of the S t r a i t  Pseudomma  concentrations half  The  September p e r i o d ,  of  approaches  mysid,  the  higher  c o n s i d e r e d i n more d e t a i l  i n Saanich  megazooplankton the  southern  two  zooplankters  Channel  in  represented  were o b s e r v e d large  will  section  only  of  i n Saanich I n l e t  Biomass was  northern  pockets  observed  the August-  overlap.  was  and  3  were  3  in  g/m )  o f f t h e mouth o f  (Figure 27).  Malaspina  Strait  A  large  t o Nanaimo  a c c o r d i n g t o e s t i m a t e s from echosounding echosounding  of  records. Table observations  b i o m a s s e s t i m a t e s which were t a k e n on e a c h  net 15 and  survey  88  FIGURE 26. D i s t r i b u t i o n o f wet {> 5 mm) i n t h e 107 kHz A u g u s t - S e p t e m b e r 1975.  biomass sound  (g/m ) o f m e g a z o o p l a n k t o n scattering layer durinq 3  89  EIGUBE 2 7 . D i s t r i b u t i o n o f wet (> 5 mm) in the 107 October-November 1975.  b i o m a s s (g/m ) o f m e g a z o o p l a n k t o n kHz s o u n d s c a t t e r i n g l a y e r d u r i n g 3  90 TABLE  15. Summary of observations on t h e 107 kHz sound scattering layer and c o r r e s p o n d i n g MNT estimates of megazooplankton biomass f o r the October 1975 cruise (75/31).  Time PDST Oct. 6 1857  Station  Biomass  Layer depthiml  Je-4  13. 40  0-40  1925  Je-3.5  2.28  0-40  2000 2127 2158  Je-3 Je-2 Je-1.5  0. 60 2.4 2 5.06  0-30 0-30 0-40  2230 2335 Oct. 7 0104 0200  Je-1 3508  4.90 1.37  0-40 0-40  2500 2254  1.00 1.23  0-30 0-30  0335  1748  1.05  0-35  0515  1230  1.39  0-30  0610 0740 1822  1036 09 35 Saa-4.7  0.20  0-20 0-20 30-110  1900 1950 2215 2230 2305 2345 0025  Sat4424 Swa4417 5723 5926 0326 0331 0430  0. 03 0.04 2. 15 1.31 0.56  -1.04  0-50 0-40 0-30 0-30 0-30 0-30 0-35  0120  0635  0.07  0-30  The approaches  28  -  composition to  November from  was  -  Saanich that  density  Very heavy l a y e r ; d i f f u s e from 40-70 m., Heavy l a y e r w i t h d a r k e r patches w i t h i n . Moderate l a y e r . Heavy l a y e r . Very heavy, e s p e c i a l l y i n t h e t o p 10 m. As above. „ Heavy w i t h d a r k e r patches w i t h i n . M o d e r a t e l y heavy. Heavy i n l a y e r , d i f f u s e from 30-60 m., Moderately heavy with darker patches w i t h i n . Heavy between s t a t i o n s , e s p . t o p 10m; d i f f u s e 30-60m M o d e r a t e , d i f f u s e t o 50m. Light-moderate p r e - d u s k ; heavy l a y e r forming. L i g h t ; s c a t t e r e d patches Light; s c a t t e r i d patches Heavy, e s p . Upper 10m. Heavy, e s p , u p p e r 15m. M o d e r a t e ; d i f f u s e 30-80m Heavy; e s p . Near s u r f a c e Moderately heavy, esp. near s u r f a c e . L i g h t ; d i f f u s e t o 70m.  and d e n s i t y o f t h e m e g a z o o p l a n k t o n i n t h e Inlet  i n the i n l e t  Intensive  sampling  performed  i n Saanich  and 2 9 ) . The M i l l e r  Remarks on l a y e r  again  differed  during  October-  proper.  o f t h e e u p h a u s i i d sound Inlet i n July  scattering  and A u g u s t  layer  1975 ( F i g u r e s  n e t h a u l s and IKMT tows a r e i n d i c a t e d  by  91  FIGURE 28. D i s t r i b u t i o n o f m e g a z o o p l a n k t o n wet b i o m a s s (q/m ) i n the 107 kHz sound s c a t t e r i n q l a y e r i n S a a n i c h Inlet, July 1975. 3  solid  a r r o w s and d a s h e d  densities, °f  g/m )  Reach  (Figure  28).  In  July,  high  o f t h e s p r i n g 1975 c o h o r t  especially  o f f Bamberton and i n  Concentrations  were  lighter  (1-2  t o w a r d t h e mouth o f t h e i n l e t .  3  In  August,  previous g/m ) (1-2  the  pattern  survey(Figure  was f o u n d  3  g/m )  29)..A  of pocket  near t h e s i l l  from t h e  of high concentration  o f the i n l e t  biomass d e n s i t i e s i n c r e a s e d of  scattering The  E. p a e i f i c a layer  fall,  by E  A  the  and J e r v i s  of  the  while  (4-8  lower d e n s i t i e s  g/m ., The 3  major  up  inlet  spring  1975  component o f t h e sound  F i g u r e 30).  total  p a e i f i c a tended  reaching  megazooplankton  to increase during  90% i n HNT s a m p l e s f r o m  November  biomass t h e summer  in  Saanich  I n l e t ( F i g u r e 30) . ,  In conjunction determinations  was  t o 2-4  cf zooplankton (cf.  percentage  contributed  Inlet  b i o m a s s was a l t e r e d  e x t e n d e d a l m o s t a s f a r a s Bamberton. F a r t h e r  3  cohort  and  respectively.  by s t r o n g r e c r u i t m e n t  Si. £§.£ifi£a » were o b s e r v e d ,  Sgually  the  aided  arrows,  with  were  the zooplankton  made  at  survey  sampling, stations  chlorophyll-a during  June t o  November. C h a r t s  of c h l o r o p h y l l - a d i s t r i b u t i o n a r e presented  as  Figures  33  of  31  phytoplankton  to  to  f o r grazing  indicate by  the  general  zooplankton  such  availability  JL. p a e i f i c a  as  l a r v a e and a d u l t s . During phytoplankton the  outer  gradient  June-July,  there  (4-8 mg C h l - a / m parts  of  the  3  were  high  standing  and o v e r ) i n J e r v i s  Fraser  R i v e r plume  o f c h l o r o p h y l l - a i n t h e plume r e g i o n  crops  Inlet  and  of on  ( F i g u r e 3 1 ) . The  i s n o t i c a b l e as  a  93  / 2 3 ° 3o'  W  UGCND . - _ oo» coNtom - I C O " CONTOW • SlAHON • MOOHDUnr 1 M X O N  FIGURE 29, D i s t r i b u t i o n c f megazooplankton wet biomass (g/m ) i n the 107 kHz sound s c a t t e r i n g l a y e r i n Saanich I n l e t , August 1975. 3  94  FIGURE 30. Change i n mean p e r c e n t a g e b i o m a s s c o n t r i b u t e d by E. p a e i f i c a  series the  of  river.  {4-8  lenses  f o c u s s e d on t h e mouth o f t h e main  I n Saanich  mg/m ) 3  were  Inlet  also  3  observed.  than  August-September  biomass tended  o f the  t o be l o w e r {2-4  latter  or higher  phytoplankton  standing  crops  i n t h e previous period i n a l l areas except  F r a s e r R i v e r plume, the  I n the northern h a l f  levels  and l e s s ) . During  lower  channel o f  generally high chlorophyll-a  S t r a i t o f Georgia, phytoplankton mg/m  o f t o t a l megazooplankton d u r i n g 1975 c r u i s e s .  a n d west  o f Texada  area, chlorophyll-a  ( F i g u r e 32) .  Island  were i n the  i n September.  In  c o n c e n t r a t i o n s r o s e t o 4-8 mg/m  3  FIGURE 31. D i s t r i b u t i o n o f c h l o r o p h y l l - a (ag/m ) i n t h e u p p e r m i n t h e S t r a i t o f G e o r g i a r e g i o n , J u n e - J u l y 1975. 3  10  97 By  October-Hoveinber  declining higher  in  the  i n Saanich  the  Strait  3.6  Discussion  for  region Inlet  of Georgia  Previous  euphausiids  data  eguation  results  from t h e  Strait  a length  Saanich I n l e t length t i p of  length  used  plate,  about  species than  reviewed  such  0.5 as  need  relationships variation Fulton's different  species,  the  mm  of G e o r g i a  by  was  part  of  Mauchline  fitted  coefficient  to  data  paeifica  indicated  region  and  combined  of regression  .  The  were  not  that  were w i t h i n  body l e n g t h s .  the  the range  F u l t o n (1968  MS)  weight r e l a t i o n s h i p of e u p h a u s i i d s  from  June-July  was  the  present  study  i n mature E.  1966.  length from by  the  paeifica  Thysanoessa r a s c h i i which  The  measure  from t h e the  measure  length , but has  eye  of  of  stalk of  the  to  body  rostral  somewhat more i n  a  longer  of  length  rostrum  ..  for in  further  investigation  euphausiids  according  to  is  stage  (1968) r e s u l t s s u g g e s t e d for  was  : weight r e l a t i o n s h i p s  i n c l u d i n g E.  plotted  Fulton  the  E_. p a e i f i c a  The  line  t e l s o n , which d i f f e r s in  B i v e r plume, b u t  3  c o l l e c t e d during  the  was  Chl-a/m ) .  been  the  biomass  i n the c e n t r a l  length  :wet  u s e d by  Fraser  3  shown f o r c o r r e s p o n d i n g  presented  phytoplankton  r e s u l t s on  and of  body  the  a single regression  Inspection  values  33)  mg/m ) and  mg  have  stated.  the  (2-4  for several euphausiid  regression  of  of  (4-8  published  Fisher(1969);  (Figure  specimens  below  indicated  by  of development that about  the 10  and  weight  evidence with  relationship mm  :  i n length  of  season, may than  be for  98  F I G U R E 33. D i s t r i b u t i o n of c h l o r o p h y l l - a m, O c t o b e r - N o v e m b e r 1 9 7 5 .  (mq/m ) 3  in  the  upper  10  99 individuals  over  Fisher(1969) states to  of  not  have  sexual  compare  different  the  sea  Strait lenqth  Beverton  weiqht  considered  and  of  Ej_  of  with  known  of  i n  the order  euphausiids  such  studies  i s to  adult  phase  f o r E._  sexes  qive  and  qrowth  i n have  applied  of  i n the  i n  body  equation, to  violating  are  mm)  to  and  the  the  exploited  these  basic  model  of  of  are  body .  length  reqressions  P e a r c e y (1971)  i n  body  between  lenqth  from  I f  the  growth  the  Application less  than  i n body then  phase.  f o r  male  5mm  carapace  increase  each  e s p e c i a l l y when body  f o r  of  phases f o r  length  increase  larvae  indicate  advised  of  carapace  adulthood.  to  adult  results,  increments  on  JEj_ p a c i f i c a  pacif ica  similar  i n 1 mm  f o r  and  equations  be  carapace  equations  f u r c i l i a  regression  pacifica  t  and  the rate  to  6.5  used  the  may  length  that  be  throughout  E  Bertalanffy  without  overestimation  measurements length  von  model  respect  regression  Smiles  knowledqe  be  of  t o 3.0  the  body  t o about  significant  sexes  Applications  indicate  adult  qrouped  detailed  and  6.  of  carapace  by  model.  (up  length  close  yield  period  to  Mauchline  relationships of  f o r both  was  furcilia  leads  that  i n d i v i d u a l s must  pacifica  the  adults  changes  the  addition,  d i f f e r e n t seasons;  described  regressions and  at  reqion  i n Chapter  The  :  exponent  of  assumptions  length  lenqth  Holt(1957)  populations  f u r c i l i a  of  L:W  well  and  out  maturity  Georqia  was  In  performed.  the of  size.  pointed  areas  y e t been  As  that  i n  length separate  Within and  the  female  measurements  are  lenqth.  reported  a  predictive  (AM)  100  regression lenqth  equation  (from  the  f o r Ji. p a e i f i c a  for conversion  p o s t e r i o r of the  o f f O r e q o n . The  where Y = t o t a l  lenqth  included  the  the  reqression  and  1960;  and  +  has  other  often  males  Por  1973;  Jorqensen  and  4.12  convertinq  that the  from  to  4.91  for  conversion  mature  the  relationships species  and  sizes was  Megan y e t i p h a n e s  v a r i e d from  4,8 7  in  i n immature f e m a l e s .  In  the  3.86  same  4.0 3 t o  ranqe  to  4.33  to  mature  the  length  =  s i z e s as  of  in  carapace  between s t u d y  the length  areas,  it  of in  females.  total  lengths  males  length,  of  by  these  immature  4.27.  For  f o r i m m a t u r e s and  4.05  species  from  Norwegian  f o r combined  follows:  3.18 ( c a r a p a c e  variation  Mauchline,  carapace  qonads,  of  qrowth  lenqth to  measurements  For  as  of  of t o t a l  t o 4.58  ripe  index  1975).  f a c t o r s were 4.27  a wide r a n g e o f  From  of  Matthews,  i n males and  4.33,  specimens.  Total  was  s t a t e d ; nor  w a t e r s , Matthews (1973) c a l c u l a t e d a r e g r e s s i o n l i n e s e x e s and  telson)  and  used mean f a c t o r s ; c a r a p a c e  males were m u l t i p l i e d by the  total  sexes  N o r t h A t l a n t i c (eq.  ratio  3.87  carapace  Mauchline(1960)  females,  the  ranqe  not  s p e c i e s such  i n the  mature a n i m a l s w i t h was  The  been u s e d as an  lenqth i n Meganyctiphanes noryegica  ratios  to  0.66  species  M a u c h l i n e (1960) f o u n d  sexually  t i p of  f o r grouped  c a l c u l a t i o n was  larger euphausiid  Matthews,  immature  the  lenqth  coefficient.  s t u d i e s on  norvegica  to  X=carapace l e n q t h .  regression  Carapace l e n q t h for  eye  equation  Y = 2.54X  in  from c a r a p a c e  length) form to t o t a l is  +  2.41.  of  the  body  apparent  reported  length that  within further  101 attention  s h o u l d be p a i d  to standardization  measurement and s t a t i s t i c a l ease  treatment  o f methods o f l e n q t h  o f the r e s u l t s f o r greater  of comparison.  The  annual  E. p a c i f i c a and  at  19-20mm,  reproduction,  origin  during  corresponded  period  toward  the  of  biomass  By  and  These s i z e s  end o f t h e g r o w i n g and  time  groups,  size  at  class for  11mm,  16-17mm  of Georgia region.  t o the o n s e t o f s e x u a l m a t u r a t i o n ,  respectively.  that  by  1975 i n t h e S t r a i t  reproduction,  of the cohort,  bloom.  of  r e v e a l e d t h r e e prominent  These s i z e s early  distribution  season,  were  the  the  final  were  period  the  o f peak  generally  reached  a c c o r d i n g t o t h e time o f  maintained  until  the  winter breeding period  spring  was o v e r a n d  growth had resumed. Brinton(1976) California  found  had c o n s i s t e n t  o f b i o m a s s a t 3-4mra, 7mm, 1956.  In  developed that  two o f t h e s e  E. p a c i f i c a  peaks i n t h e annual s i z e 10-12mm and a t  a t 17 and 18mm,  respectively.  t h e peak a t 3-4mm was due t o t h e i n the early  The  peak c o r r e s p o n d e d  7mm  juvenile  phase  corresponded relation sizes  furcilia  while  with  the  to the Strait below  11mm  populations as these  off  15mm  phase  during  Brinton(1976) consistent  (likely  peaks  reproductive  of Georgia  at  1953 t o peaks  abundance  from  larger  periods  of  1950).  larval  to  sizes  likely  referred  to i n  p o p u l a t i o n s . The biomass  were n o t o b s e r v e d  also  considered  F 3 ; c f Boden,  with the t r a n s i t i o n the  southern  distribution  y e a r s , 1954 and 1956, b i o m a s s  larvae  at  that  i n the Strait  peaks  o f Georgia  s t a g e s were o n l y p r e s e n t f o r a s h o r t p e r i o d  of t h e year r a t h e r than  at a l l times o f t h e year as i n  southern  102 California  waters.  Total Georgia end  biomass  of  B.  paeifica  populations  r e g i o n g e n e r a l l y peaked i n O c t o b e r  of the growing season;  reached  sizes  of  to  rise  November  appeared  improving  survival in this interval.  of r a p i d  t o a drop i n t o t a l biomass i n J e r v i s I n l e t .  Georgia  between O c t o b e r  Off  for the  of E  total  lengths  of  This  promote  size  uniformity  breeding  efficiency  of Georgia and  "piling-up"  Production  were  may in  for  Such and  the  declined  late  of The  significantly  summer  noted  represent the  in  the  fall  a  staging and  s p r i n g (Br i n t o n ,  seasonal  1976).  populations due  to  the to  higher In  the  phytoplankton  their  u n i f o r m i t y , as  estimates  body  period hence  declines i n through  had  and  of biomass at  population  E. p a e i f i c a  previous  Strait  23).  build-up  temperatures,  local  pattern  i n December.  of s e v e r a l c o h o r t s i n the l a t e f a l l  comparison with  decline  a  of a d o l e s c e n t s t h e n  regular  r e g i o n , the  of  the  and  peaks  growth r a t e s , l e a d t o g r e a t e r s i z e the  rates  to  most s u c c e s s f u l o n e s , major  i n the e a r l y  water  period  fall  1976); t h e c o h o r t s  8-12mm.  the  and  biomass  transition  abundance  had  where t h e  are the  juvenile-adult  Strait  Inlet  been monitored  cohort  California,  E.. p a e i f i c a  winter(Brinton,  Saanich  November c r u i s e s ( F i g u r e  paeifica  A  had  Inlet  and  southern  cohorts in  expected  Saanich  growth  of  i n c r e a s e d m o r t a l i t y of second-year a d u l t s  populations i f they  second-year  this  A f t e r October,  led  be  by  at  i n b i o m a s s f r o m June  growth  also  and  the r e s u l t  had  in  would  rates  be  rapid  Strait  t o November,  the s p r i n g cohorts  13-17mm. The  i n the  impacts  evidenced  on by  and  winter.  was  examined  Lasker(1966) ,  103 based data  laboratory studies of E  on from  the literature(eg. estimate  that  E. p a e i f i c a  i s needed  to m a i n t a i n  of  estimate its  the  2  range  obtained  in  Lasker's  16%  the  ingested  of  production (Mullin, production be a b o u t  et  E. p a e i f i c a  i s thus  not  version  about  size  would  of this  of  E. p a e i f i c a increase  the l i t e r a t u r e over  is  used  for  basis,  The  value  that  growth  the  3.0 / y e a r for source  of  (Crisp,  further  and  mean  rate  of  would  production  (from  estimated  1975). T h i s  of error  egg  Pacific  P/B  production  about  by  for  estimate  animals  in this  lost  estimate i s  rates of laboratory  specimens  r a n g e were assumed t o be a p p l i c a b l e t o d i v e r s e In  be l o w e r  addition,  than  the  the  annual  summer  rate  net used  primary in  one  estimate.  study  more  based  i n biomass.  offered  an o p p o r t u n i t y  well-defined on  observations  The  j9JJcifica  i n the S t r a i t  one  on  based  was  8  this  allowance  present  production  and  b i o m a s s o f E. p a e i f i c a  o r 0.48% o f n e t p r i m a r y  populations.  The  respiration  budget f o r E_ p a e i f i c a  growth r a t e s and r e s p i r a t o r y  production  the  On  mortality. A further  natural  growth,  by t h e p o p u l a t i o n . I t  a l , 1960).  include  of a l i m i t e d  JL.  the  Lasker's  i n t h e biomass o f  o f t h e n a t u r a l p o p u l a t i o n i n t h e North  McAllister  that  the carbon  From  field  2  carbon  0.9 mgC/mVday  through  1963).  e a c h d a y , and from  carbon  1969).  g r o w t h and on  O c e a n , a v a l u e o f 5.5 mgC/m /day was  f o r daily ingestion from  of  f o r the l i v e  the P a c i f i c  estimated  does  5%  population  o f 110 mgC/m  paeifica  Ponomareva,  laboratory  moulting  t  values  on  populations  of  r a t e s o f m o r t a l i t y and estimated  for  o f G e o r g i a r e g i o n a r e much h i g h e r  than  Lasker's(1966)  of  coastal  to estimate the  production  carbon  budget.  The  local  104 populations than  had a mean P/B r a t i o  Lasker*s  by a b o u t  likely  be a t t r i b u t e d  local  populations  o f 8.9 ± 0.56 w h i c h was  three times.  to t h e higher compared  Much o f t h e d i f f e r e n c e c a n  growth r a t e s o b s e r v e d  the  contribution  mortality  i s i n c l u d e d i n the present estimates.  production copepod  literature  species  E,  reported for  E  (26.8  meqazooplankton  to  from  Inlet  from  and  z  the  throuqh  zooplankton for  about  at  niqht  i n the S t r a i t i n the hiqh  on  P/B  (0.0 24/da)  be  detectable  recordinq  not durinq  cruise  the  discussed  scatterinq  patchiness  euphausiids i n Saanich  survey  the d i s t r i b u t i o n  of values  tows  was  scales by  with  layer(cf. within  estimate  o f biomass o f  the  larqe-  sound s c a t t e r i n q usually  one  layer.  nautical  o f p a t c h i n e s s below net  t r a n s e c t s with  thouqh, o f t e n d e t e c t e d patches  for  due t o L a s k e r ( 1 9 6 6 ) .  frequency  3m/sec),  would  values  o f Georqia reqion revealed  at  minutes  net  sinqle  0.2 t o 77  a r e t h u s w i t h i n t h e ranqe  m i l e (10  of  ranqe  mqC/m /da)  Miller  The  of  lost  0.002 t o 0.50 / d a y . The  As t h e l e n q t h o f  within  much  i n the Sorth P a c i f i c  patchiness  limit  individuals  f o r h e r b i v o r o u s c o p e p o d s , but h i q h e r t h a n t h e  Observations  scale  found  i n Saanich  pacifica  x  to  up t o 1968. P r o d u c t i o n v a l u e s  P/B v a r i e d  production pacifica  due  reviewed  were  mqC/n>2/day w h i l e of  has  i n the  t o L a s k e r * s l a b o r a t o r y a n i m a l s . In  addition,  Mullin(1969)  higher  samplinq.  this  Continuous  a 107 kHz e c h o s o u n d e r ,  diameters  l e s s than  a  mile  Table  1 5 ) . P i e p e r (1971) h a s  sound  scatterinq  layer  of  Inlet.  cruises  indicated  the presence  of several  areas  h i q h abundance o f megazooplankton, e u p h a u s i i d s i n p a r t i c u l a r .  105 These i n c l u d e Saanich from J e - 5 ) , and west the  of  in  of  i n the  and  high  i n the  within the  euphausiid  catches  will  be  concentrations Crofton area  (see  by  not  from  ( S t a t i o n 1748  of  an  annual  December ( S t e p h e n s e t Ej_ p a c i f i c a  For and  high  estimates  showed  the  T^inermis  on  Gulf  of  and  A  maximum  the  of  fishery  indicate  high in  the  toward  the  distribution  of  Strait  by  the  Miller  vertically  sound  similar present  the  noryegica (Berkes,  to  layer. central  1966-1968 to  that  about observed  study.  St. Lawrence e s t u a r y , on  during  October  net  migrating  scattering  study)  have  Parsons et  hauls(400m-0) i n t h e  1969)  reported  of Georgia  daytime  during  i n the  longicaudata  plankton  also  from  present  Meganyctiphanes T  were  vertical  populations  shift  distribution  , MS{1969) and  freguency  the  The  megazooplankton  occasionally  sampled  a l . . . MS,  Sameoto (1976) h a v e  euphausiids,  data  have  of  1) .  Stephens et a L  would  to  i n Sechelt Inlet,  i n the s u r f a c e waters of the  megazooplankton of t h e  for  Figure  and  part  plume.  tended  the  the  5  occur  Channel,  River  of Georgia  Chapter  studies(1965-1967)  which  Strait  Strait  inlet areas:  central  of Georgia  on  down  following  Fraser  Data  in  ( 1 9 7 0 ) ; however, t h e i r  Biomass  Strait  euphausiids  of S t u a r t  reported  tows  the  Nanaimo i n t h e  of the  inlets.  presented of  Earlier  al..  of Georgia  vicinity  from t h e  mouth o f Howe Sound  zooplankton  (especially  between c r u s i e s much more t h a n  populations  been  Strait  abundance i n t h e  location  which  Jervis Inlet  Texada I s l a n d ; n o r t h o f  Strait;  areas  Inlet,  Berkes(1973;  distribution , Thysanoessa only).  of  1976) the  raschii  .  Sameoto(1976)  106 used  a  120  scattering three  kHz  echo s o u n d e r  l a y e r s which  euphausiid  to r e c o r d the  were  comprised  largely  s p e c i e s m e n t i o n e d above.  relationship  between i n t e n s i t y  of  of  and  euphausiids  numbers  collected  on  the  He  of  found  In  the  chlorophyll-a  in  first  density  concurrently  during  flay  y e a r s (1972-74)  the d e n s i t y of the  sound  a consistent  from  addition,  of  the  b a c k s c a t t e r i n g and  successive  between  amount o f  of  samples.  three  correlations and  biomass  plankton  cruises  distribution  or  June  significant  sound s c a t t e r i n g l a y e r s  the  surface  waters  were  noted.  In  summary,  Georgia  populations  r e g i o n were o b s e r v e d  E±  of  to reach  JBScifica  June-October,  proportion  of the  scattering indicated  layers  of  that s i z a b l e  100,000 m e t r i c the  total  shallow  tons  paeifica  study  stocks  production  contributed  megazooplankton the  biomass  areas.  of  The  in  of  d u r i n g October-November Strait  summer.  an  increasing  in  the  survey  megazooplankton  s c a t t e r i n g l a y e r s o f the  Strait  maximum b i o m a s s i n O c t o b e r  t o November, f o l l o w i n g t h e p e r i o d o f h i g h During  i n the  1975)  sound cruises  (e.g.  are  about  present  in  region  at  biology  of  of Georgia  night. To  conclude  E. p a e i f i c a population the  very  , I will  ideally  consider  between t h e  following generation  difficult  since  discussion  biology, especially  relationship  of the  the  a  wide be  a  on  problem  observed  and  population which  is  central  to that of e x p l o i t e d s i z e o f the  parent  sizes  for  stock  of a d u l t and  the e f f e c t  natural filial  of environmental  to  populations:  (e.g. L a r k i n , 1973). The  to resolve empirically range of  the  and  that  guesticn i s populations  stocks  should  variability  107 on  reproduction  Consequently, to  construct  recruitment  a f a v o u r e d approach  about  the  action  f o r example,  and  into  account.  b i o l o g i s t s has  recruitment of density  as p r e d a t i o n , g r o w t h r a t e s  Ricker(1954;1958)  taken  of fishery  models f o r s t o c k and  assumptions such  and  based  on  dependent  fecundity.  been  simple  mechanisms  The  model  of  assumes:  " t h a t t h e a v e r a g e abundance o f t h e p r e d a t o r s ( d u r i n q the t i m e o f t h e i r c o n t a c t w i t h t h e p r e y ) v a r i e s from year to year, as some constant f r a c t i o n of the i n i t i a l abundance o f prey (fish eqqs or larvae, etc., at whatever s t a q e c o m p e n s a t i o n b e q i n s ) , but t h a t t h e p r e d a t o r s have a minimum abundance w h i c h i s s u s t a i n e d by t h e i r o t h e r f o o d s . "  ks t h e p r e d a t o r s c a n parents  of  species and of  the  eqqs  or  more t h a n larvae  to function  the compensatory  proceeds parental  and  equilibrium  a t some  as a c o n t r o l ,  at the hiqher  these to the  that  assumptions,  the  followinq relation filial  stocks  replacement  Z  is  abundance,  W  the  replacement  ratio  "a" to  is  include  density  merely  of  shifts  predator  prey a  or  part aqent  are  mathematical  (Ricker,  1958),  expressed  derivation  i n which  i n terms  of  the their  values:  of  i s the r a t i o  a b u n d a n c e , and  and  density."  Z = 8-exp £ a (1-W) where  species  mechanism t o some o t h e r  can f u n c t i o n  From  one  i n question, then i f a qiven  o f p r e d a t o r "becomes s a t i a t e d  ceases  which  be  filial  parental  abundance  of parental  the  ratio abundance  1  of  to  replacement  abundance t o parental associated  replacement  abundance with  at  maximum  reproduction. From c o n s i d e r a t i o n  of  a  theoretical  situation  in  which  108 competition derived  f o r food  the  same  limits  growth r a t e , Beverton  expression.  with  higher  then  d e n s i t y dependent r e g u l a t i o n i s  The long  rates of predation  As s l o w e r  present  study  and H o l t ( 1 9 5 7 )  growth r a t e i s l i n k e d  on t h e e a r l y s t a g e s  of the  accomplished.  was n o t c a r r i e d  out over  a sufficiently  p e r i o d t o m o n i t o r a wide r a n g e o f p a r e n t a l and f i l i a l  densities  necessary  recruitment  t o apply t h e e m p i r i c a l approach  question  f o r E. p a c i f i c a  above  critically  examined t h r o u q h f u r t h e r f i e l d  questions  provide  minimum a d u l t s t o c k  of  mature  higher could without  ( c f . S i c k e r , 1958)  the  mortality  the stock's  The  adult stock  possible  reproduction  cohort.  Therefore  maximum r e p r o d u c t i o n Ricker's replacement  are  where Z ^ i s t h e r a t i o  and  fishing)  to  ratio  of  possess  generate  be  a  t h e maximum replacement  i n the r e l a t i o n  replacement  o f maximum f i l i a l  abundance. In o r d e r on  either  to evaluate  between  reproduction.  maximum  reproduction  the  Saanich  abundance t o  From to  conditions.  Inlet  replacement  this expression  the a d u l t or f i l i a l  under maximum a n d r e p l a c e m e n t harvesting,  (natural  1/a • e x p ( a - 1)  m  information  (b) how much  reproduction i s : Z =  filial  stock  thus  interested  and s i m p l e the  i s  and  (a) would  rate i n order  equation,  what  production?  in situation  we  h e r e a r e (a)  t o produce a replacement  progeny?  lowering  as  studies.  interest  necessary  total  to the stock  a p r e l i m i n a r y view which c o u l d be  of p a r t i c u l a r  the  stock  . However, a model s u c h  described  The  can  prey,  population  relative In  the  one needs abundances  absence  of  of euphausiids f o r  109 instance, there  has  i s  no  variability inlet  evidence  Bary  et  mortality  significantly  subseguent density  then  over  level  the  be  relation  reproduction  the  indicate  the  o f t h e stock recruitment curve  to  c a t c h and l i m i t i n g  times  harvested  can  be  determine  Ej_ p _ a c i f i c a  several  possibility  nature  of  relationship.  i s protracted  of  in  calculated.  a reliable  Saanich  reproduction  ( B r i n t o n , 1976).  adult  be r e a l i z e d  spawners,  populations over  more  and r e p l a c e m e n t  s h o u l d be examined  more  a period  i s obtained,  eguilibrium  that  Inlet  Although  i t  Under of  maximum  the  spawning  possibly  spawn  conditions  of  the r e p r o d u c t i v e  still  thoroughly  the  c o u l d e a s i l y be  since  of years.  rate  stock recruitment  (May-September) and f e m a l e s  per season  might  were  of recruitment could  season  potential  and P i e p e r , 1 9 7 0 ) . I f h i g h  present i n f o r m a t i o n , i t appears  density  that  s t o c k , then t h e  s e v e r a l times t h e replacement  lower  o f high  spawning  (Bicker,1958)  of  19 61-77  adult  premature from  from  as  levels of euphausiids i n  a l ^ ,1962; B a r y  t h e maximum e g u i l i b r i u m  would  period  levels  (or adverse environmental c o n d i t i o n s )  shape  of e x p l o i t a t i o n  the  biomass  reduce  dependent  If  been r e p r o d u c i n g a t r e p l a c e m e n t  i n t h e annual  {cf.  harvesting to  likely  achieved. This by  monitoring  110 CHAPTER 4:  4.1  EUPHAUSIIDS AS  Introduction  If  harvesting  commercially potential time, the  then  uses  of  zooplankton  further of  the  growth  response can  zooplankters  in  information products  essentially  be  useful  the  in  marine f o o d  negative  indicated  crustaceans  results  a  experiment  web. a  Methods f o r C h e m i c a l  Analyses  ash),  was  proximate  same  zooplankters to  the  the  food  by  as food  analysis  of a January A.  analysed  zooplankton  a n a l y s e s were p e r f o r m e d  and  of  the  zooplankton for  fish,  B r e t t (1971) on f o r young  the  use  the  salmonids  of  for rearing  of l o c a l  on  marine  young  fish  euphausiids  and  coho a r e d e s c r i b e d b e l o w .  amino  1975  Barnes o f the  for l i p i d  and  role  superior  analysis(crude protein,  Canada, Vancouver L a b o r a t o r y .  acid  o b t a i n e d . At t h e  s a m p l e s were s u b j e c t e d t o t h e f o l l o w i n g  k i n d l y s u p p l i e d by  personally  and  live  of  importance  composition  as a d i e t  c a r o t e n o i d d e t e r m i n a t i o n , and  proximate  in  Although  the composition juvenile  analyses:  the  assessing  reappraisal  with  Euphausiid  of  obtained  as E.. p a c i f i c a  n e e d e d . A n a l y s e s on  a growth  of  that  such  be  develop  of experimental animals  v a l u e o f f r o z e n marine z o o p l a n k t o n  4.2  on  must  have been g e n e r a l l y r e c o g n i z e d as  have  i s to  d a t a on t h e c h e m i c a l c o m p o s i t i o n  preparations  is  A FOOD  crude acid  sample f r o m  chemical  lipid, analysis.  fibre, The  Saanich  Inlet  F i s h e r i e s Research  Board  Further  frozen  samples  were  c a r o t e n o i d c o n t e n t . The  amino  u n d e r c o n t r a c t by  Dr.  J.  SheIford  111 at  the  Department o f  For  the  Kjeldahl  proximate  by  Science,  analysis,  determination  Steyermark(1961) . (1:2  animal  volume).  of  Lipid Ash  of  the  association  crude  a t 525  fibre  of O f f i c i a l  p r o t e i n was as  found  by  C.  twice  Details  determination  Agricultural  by  the  described  extracted i n chloroform:  determined  sample i n a m u f f l e f u r n a c e and  %  .  nitrogen  was  was  UBC  by  methanol  combusting  of t h e s e are  the  procedures  given  Chemists(1960)  in  the  manual  of  analysis. Lipid according The dried in  6  does  and to  carotenoid  analyses  euphausiids  not  determined  i n our  laboratory  Herring(1972).  amino a c i d  N HCl,  were  on  f r e e z e - d r i e d , f r o z e n and  steam-  were p e r f o r m e d f o l l o w i n g h y d r o l y s i s f o r 24  according  to  Spackman e t  give q u a n t i t a t i v e recovery  al.  (1958).  This  h  method  of c y s t e i n e , methionine  or  tryptophan.  4.3  4.31  Fish  Feeding  Trials  with  from C a p i l a n o  the  of the  Initial  Hatchery,  fish  diets.  separated  fish  Preparations  Methods J u v e n i l e coho salmon  all  Euphausiid  into equal forklength  from e a c h The  to  k i s u t c h ) , were  Department of the  were k e p t  Prior  { Oncqrhynchus  i n one  the  Environment.  tank f o r one  feeding  trials,  groups i n f o u r i d e n t i c a l and  wet  w e i g h t was  week t o the  obtained Initially introduce  548  fish  fibreglass  estimated  by  were  tanks.  sampling  26  tank.  four fish  diets included three euphausiid  preparations  112 and  a  control  diet  o f Oregon m o i s t  (Halver,  1972), p r e p a r e d  LaConnor,  Washington.  minced f r o z e n , moist  (2)  pellet.  plant at P a c i f i c  This  equipment,  liquid and  and  To from raw  make  Saanich  three  Co.,  Inlet  p a r t s by  San To  dried  Company,  processed'  West  Research  meal  Vancouver.  Organization, press  partially  m a t e r i a l . The  (1)  with a f i s h  worm-drive  press  raw  and  a  separates  the  unit  then  meal, f r o z e n e u p h a u s i i d s  i n January  and  p r e s s i n g and one  February cooking  part l i g u i d  weight of the  with  Chemical  2  cooks  fraction.  adding  a Laboratory  1975  were u s e d  the dried  fraction.  Pellet  Mill  as  the  product  e x t r a c t from  dried  collected  the  The  was  press  to  mixture  was  Pellet  Mill  (California  Francisco, Calif.) standardize the  and  pelleted  through  a  No.  retained  on  a No.  were minced i n t o The  fixed  weight per  day,  eguivalent  dry  continued  particle  16  O.S.  30  Standard  sieve  of the diets,  daily  rations  t o 17%  weight  for  1-2  After 21  mm  two  The  OMP  freeze-  meal were 1.19  mm  frozen  passed  meshes  and  euphausiids  (30% o f i n i t i a l  body w e i g h t  were  the  long.  of a l l d i e t s  of f i n a l basis)  the  Sieve with  (0.595 mm).  p i e c e s about  14  size  e u p h a u s i i d m e a l s and  growth r e g u i r e m e n t s . trial  The  prepared  No.  were  meal  Institute,  a  Formula  preparations  (3) a ' f i s h was  basically  the euphausiid  by  pelletted  the  p a r t s o f the  material. After  moistened  diet  by  is  d r i e s the s o l i d  and  (OMP)  Moore-Clarke  euphausiid  dryer-cooker. solid  by  Environmental  built  Denmark,  steamheated  The  latter  pilot  Esbjerg,  commercially  freeze-dried  The  pellet  per  set i n excess  d a y s o f no  feeding,  d a y s w i t h once d a i l y  day  on  body an  of  expected  the  feeding  feedings  between  113 1030  and  1430  The  four  fibreglass  tanks  difference  to  the  h to c l e a r  end  their  measured  and  growth i n l e n g t h and  4.4  Results  Composition The  analysis  proximate of  marked  carotenoid/g Possible  bottom  outdoor The  courtyard  flushing  inlets  and and  in  rate  four  of  the  in  the  surface outlets relatively  was  uniform  r a n g e 8-10.5 C ) . a n a l y s i s o f v a r i a n c e readings  revealed  means a t t h e  guts. wet  no  the f i s h  A l l of the f i s h  were  level.  were s t a r v e d killed  weighed f o r c o m p a r i s o n  on  significant  1% s i g n i f i c a n c e  of the experiment  of  then  treatments  weight.  composition from  lipid  and  with  of t h i s  of l o c a l  Saanich  variations  tissue)  sources  maintained  Euphausiids  a catch  Later analyses of revealed  of  the  a t OBC.  temperature  for  4.41  in  between t h e t a n k  Prior  directly  1)  were  oxygen s a t u r a t i o n  (mean 9 C,  surface  24  with  to maintain  temperature  for  (200  groups  Sciences Building  freshwater  daily  experimental  tanks  Biological  adjusted  PDT.  euphausiids,  Inlet,  carotenoid (6.6  date  variation  to of  i s shown i n T a b l e content  19.6%  be  (Table  lipid,  collection  will  based  80  and  discussed.  t o 219  on 16a. 16b) ug  location.  114 TABLE  16a. Proximate composition of euphausiids S a a n i c h I n l e t , J a n u a r y 1975. Dry w e i g h t b a s i s . Component Protein Lipids Ash Crude F i b r e  caught  % 69.1 17.3 11.1 2.5  TABLE 16b. L i p i d and c a r o t e n o i d c o n t e n t o f c o m m e r c i a l e u p h a u s i i d s from Sechelt and Saanich Inlet. weight b a s i s . Inlet  Date  Sechelt Sechelt Sechelt Sechelt Saanich  1816012016-  The  amino  LipidXll  31/Jan/77 28Feb/77 11/Mar/76 31/Mar/76 23/Feb/76  acid  catches Dry  C a r p t e n o i d (flq/q)  19. 6 13. 1 11. 0 9. 0 6. 6  compositions  p r e p a r a t i o n s of e u p h a u s i i d s , used  219. 94. 80.  of  in  the  the  j u v e n i l e coho salmon, a r e g i v e n i n T a b l e TABLE  in  protein  feeding  of  trials  three with  17.  17. Amino acid composition of three preparations of euphausiids from Saanich Inlet in January and F e b r u a r y 1975. L a b e l s a r e e x p l a i n e d i n the t e x t . Preparation  FDE  EM  FZE  DryMatter  91.6  74.5  17.0  %  ASiS2 A c i d Alanine Arqinine Aspartic Acid Glutamic Acid Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tyrosine Valine  mg  aa/mq s a m p l e x 3.34 3. 58 5. 93 7. 16 3.91 1. 24 2.59 4. 21 3. 33 1.76 2. 87 2. 10 2.31 2.70 2. 33 2. 66  VOQ  Jdry, wt  2.40 2.62 2.98 5.35 2.59 .68 2.01 3. 17 2.34 •1. 40 1.85 1.31 . 58 .91 1.46 2.03  basis) 3.94 2.91 6. 52 4. 17 4.68 1.46 3.08 4.67 5.03 2.07 3.30 2.07 2.59 2.98 2.36 3.11  115 4.42  J u v e n i l e Coho Growth  on E u p h a u s i i d  The  the  results  effectiveness are  final  growth  of three euphausiid  summarized  illustrate  of  i n Table  the  changes  o f t h e OMP  experiment  in  wet  q r o u p was  w e i q h t between Althouqh  marqinally  ( FDE ) q r o u p had t h e h i q h e s t  3.8%  body  for  euphausiid was  wt/day,  the euphausiid  hiqh,  standard  test  the  to  OMP  p r e p a r a t i o n s compared  euphausiid wet  to  18. F r e q u e n c y d i s t r i b u t i o n s i n F i g u r e  samples f o r each treatment.  weiqht  Preparations  compared  meal  ( EM  especially  in  the  final  hiqher, mean  2.8%  and  EM  mean  qrowth  for  qroup v a r i a t i o n FZE  and wet  the f r e e z e - d r i e d  t o 3.1% f o r the OHP  ) q r o u p and  ( F Z E ) qroup. Within  the  the i n i t i a l  34  rate  qroup, the  at 3.0%  frozen  i n qrowth  rates  q r o u p s , where t h e  d e v i a t i o n s e x c e e d e d t h e mean q r o w t h r a t e s .  TABLE 18. C o m p a r i s o n o f i n i t i a l and f i n a l mean values for weiqht and f o r k l e n q t h a s w e l l a s mean qrowth r a t e s o f d i e t q r o u p s i n coho f e e d i n q t r i a l .  wet  Mean j s _ . dj, i_  Euphausiid Preparations Frozen Freeze-dried  Meal  Control OMP  Initial wet w e i q h t  276.0 (8.6)  297.3 (7.5)  329.9 (5.4)  349.2 (8.0)  Final wet w e i q h t (mg) Initial forklenqth (cm)  532.3 (52.7)  684.0 (46.8)  643.6 (47.6)  692.6 (48.9)  3. 16 (.06)  3.21 (. 04)  3.24 (.02)  3.24 (.04)  Final forklenqth (cm) Growth r a t e (%body wt/ day)  3.65 (.16)  3.87 (.13)  3.73 (.12)  3.87 (.13)  2.67 (5. 53)  3. 76 (2.94)  2.95 (3.08)  3.05 (2.80)  Statistical  siqnificance  one-way c l a s s i f i c a t i o n  o f the  results  a n a l y s i s of variance  was  assessed  by  { ANOVA ) ( S o k a l  and  116  BEFORE  AFTER A. FROZEN'  20  15 10 5 0| 20  B.  FREEZE-DRIED  15 10 5 0 20  *-n  C. MEAL  r-i  n  15 10 5  D. OMP  .2  .3  .4  .5  .6 .2 .3 WET W E I G H T (g )  .4  .5  .6  .7  .8  .9  10 1.1 1.2  FIGOEE 34. Frequency d i s t r i b u t i o n s of wet weiqht for juvenile coho sampled b e f o r e and a f t e r f e e d i n g t r i a l s on four diets: a. Frozen euphausiids, B. F r e e z e - d r i e d euphausiids. C. Euphausiid meal, D, OMP ,  R o h l f , 1969) and by Scheffe*s(1959) l e a s t s i g n i f i c a n t d i f f e r e n c e (  LSD  ) procedure. The ANOVa t e s t s (Table 19) e s t a b l i s h e d that  there were h i g h l y  significant  treatments f o r f i n a l growth r a t e s .  (P<  0.01)  differences  between  mean wet weights and f o r k l e n g t h s as w e l l as  117 TABLE 19. Summary o f ANOVA on f i n a l wet w e i g h t s and growth r a t e s o f t h e f o u r c o h o d i e t g r o u p s . Source  df  of Variation  F i n a l wet w e i g h t treatment within treatment Final forklength treatment within treatment Growth r a t e treatment within treatment  SS  MS  found  t h e LSD p r o c e d u r e that  significantly forklengths  the  1.81 23.55  .603 .0535  11.27**  3 440  3.94 64.52  1.31 .147  8.95**  3 440  71.6 3 1746.  23. 88 3.97  6.01**  lower of  f o r comparing  mean  wet  weight  (P<0.01) t h a n  the  FDE and OMP  the groups  of  other  the  other d i e t  FZE  means.  were a l s o  growth  FDE g r o u p  ( T a b l e 20) i t was  the  o f t h e FZE and EM g r o u p s .  of  P<.01  means,  higher than those rate  I  3 440  ** By  forklengths;  was h i g h e r  group  was  The  mean  significantly  Finally,  the  mean  (P<.05) t h a n f o r t h e  groups.  TABLE 20. C o m p a r i s o n o f means f o r diets by s i g n i f i c a n t d i f f e r e n c e ( LSD ) method.  Scheffe's  least  Means  Frozen FZE  Meal EM  Control OMP "  Freeze-dry FDE~ ~  LSD (prob)  Wet Wt (mg)  532.3**  643.6  692.6  684w0  104.4 (.01)  Forklength (cm)  3.65**  3.73*  3.87  3.87  . 14 (.05) .16 (.01)  Growth Rate {% body wt p e r day)  2.67  2.95  3.05  3.76*  .706 (.05) . 85 (. 01)  *P<.05 **P<.01 Note that LSD i s the smallest s t a t i s t i c a l l y significant d i f f e r e n c e between compared means and c a n be c a l c u l a t e d a s d f x F(cr) x standard e r r o r o f t h e d i f f e r e n c e between t h e compared means ( S c h e f f e , 1 9 5 9 ; S o k a l and R o h l f , 1 9 6 9 ) .  118 4.5 D i s c u s s i o n  4.51  Composition  Due  especially  proteins, for  rapid  qrowth  derived  baleen  of  their  t o be an e x c e l l e n t c o n s t i t u e n t  animals.  Certainly  a  qood  whales which f e e d  i n t h e Southern  results from  example  i s  almost  entirely  Ocean and i n t h e N o r t h  Pacific  presented  his  multiplying  by  determinations,  Kjeldahl 6.25  with  values i n  euphausiids  noryegica  to  of  body %  prior  with time  from  Sechelt  late  winter.  rasehii  t o spawning  carotenoids,  from  protein  71.9%  for  of year  was  and  drops.  Although  are  Inlets  of  Meganyetiphanes  F y n e , S c o t l a n d . The with  use  f o r egg  i n l a t e March and A p r i l .  appear the  similar  five  noted,  Saanich  associated  a s t a x a n t h i n and i t s e s t e r s to  present  decline data  they i n d i c a t e t h a t euphausiids  region  by  F i s h e r e t a l . ,(1954)  Loch  t o be  predominantly also  values  nitrogen.  m a i n t e n a n c e d u r i n g w i n t e r a n d , i n some f e m a l e s ,  preliminary, Georgia  values  with  65 t o 81.21.  r e s e r v e s appears  ( F i s h e r e t aJU , 1955) content  agree  pacifica  A  mean  content  durinq  and T h y s a n o e s s a  production  The  protein  trends i n the f a t content  depletion of l i p i d body  lipid  markedly similar  a  a r a n q e from  of  observed  %  nitroqen  yields  Variation  declining  for  L a s k e r ' s (1966) d a t a on E  Converting  for  of  quality  (Nemoto, 1957; 1959; 1968) . The  with  Euphausiids  t o t h e q u a n t i t y and h i g h  of qrowinq  upon e u p h a u s i i d s Ocean  of Georgia  euphausiids are l i k e l y  the diets  the  of Strait  as  the  lipid  must be r e g a r d e d  as  in  of  the  Strait  i n carotenoid concentration to the  119 p e l a g i c red  crab,  Pleuroncodes  California  which  has  feed  ingredient  (Wilkie,1972: total  tissue(mean The E.  favourable protein.  Levels  indicating  during  the  FDE  frozen  diet  favourably  that  ) g r o u p had The  was  the  more  of the  coho w h i l e  cloudiness consumed  due  within  to  the  meal  the  { EM  the  of  l o s s of  processing.  and  diet  there  was  the  OMP  freeze-  over  more f a v o u r a b l e was  range  of  the  the  surface  bottom  frozen euphausiids,  the  freeze-  tended to  sink t o the  than  amino  in  Thus, the  euphausiids to  based  growth r a t e  difference  within  the  protein  ) groups, the  fish.  a  were  than f o r  Although  higher  of  a dietary  % recovery  freeze-dried  frozen  With t h e  as  have  the e u p h a u s i i d  diet.  a result  surface  leaching  seconds.  OMP  r a t i o n to the  minced  animal  mean growth r a t e s o f  likely  daily  and  s t a g e o f meal  the  ) and  not  obtained  proteins  preparations  a significantly  clearly  meal f l o a t e d a t t h e  feeding  with  s u p e r i o r i t y of  composition;  availability  { FZE  salmonids  preparations  significant  pressing  d i f f e r e n c e between frozen  of  aguacultural  whole  three  amino a c i d s  freeze-dried  s h o r t term o f t h e  the  others.  dried  the  show t h a t  important and  Gulf  units.  experiment,  {  acid  of  Eor  compared  an  pen-reared  99  Diets  g r o u p and  the  to  as  the  Wilkie(1972)  Coho Growth on E u p h a u s i i d  the  from  e s s e n t i a l amino a c i d s f o r use  of the  meal,  significant  dry  83  of  ,1974).  A  compositions of  frozen  occurred  diets no  acid  balance of  euphausiid  4.52  of  a l  from S a a n i c h I n l e t  f o r the  likely  et  i n astaxanthin  amino  jOacifica  higher  t o enhance p i g m e n t a t i o n  yields  93)  ,  r e c e n t l y been suggested  Spinelli  pigment  pianipes  the  cause i f not more  120 aqgressive poorly; small  growth  values  growth  rates  but t h e t i m i d  reported  rate  is  for  weight  temperatures  juvenile  the  keta  T  in  the  salmon  effect  on  live  present  o b s e r v e d a growth  feeding primarily  13.5 C i n a f u l l - s c a l e ). I n c o n t r a s t , Oncorhynchus  of  weight  of  water  rapid  temperature  on  x  Controlled  experiment.  i n young  Koeller  salmonids.  and  a t 10 t o  j u v e n i l e sockeye  m  3  salmon,  1.5% p e r day on f r o z e n based  on  fish  meal  r a t i o n s o f 6% d r y body  are  reduce s i n k i n g  f o o d s c a n be e q u a l l y  ambient  E x p e r i m e n t a l Ecosystem(1700  a t 15 C g a i n e d o n l y  f o r m s which  chum  increased  on l i v e C a l a n u s p l u m c h r u s  Brett(1971) found that  nerka  meal  growth  related  r a t e o f 4% p e r day f o r j u v e n i l e  p e r day. The p r e s e n t f i n d i n g s  crustacean  closely  on e x c e s s d i e t s  a t up t o 2 . 8 % p e r day on f i x e d  In  bits.  including  contrary  contention that crustacean foods are i n f e r i o r foods.  the  zooplankton,  Cala£fi§ PiiJSSllESs whereas t h o s e f e d d i e t s increased  as  5.4% p e r day, b u t a t c o n s i d e r a b l y warmer  than  Parsons(1977) salmon  as t h e f r o z e n  i n t a n k s a t 14-16 C. F i s h at  was more e v e n  considered. LeBrasseur(1969) f e d j u v e n i l e  Oncorhynchus  euphausiids,  ones d i d  o b t a i n e d i n t h i s experiment a r e comparable  e s p e c i a l l y when  salmon,  chum  well,  p e l l e t s d i d not s i n k so r a p i d l y  species,  in  were a b l e t o f e e d  w i t h t h e o t h e r meals, d i s t r i b u t i o n  The to  fish  to  to fish  Brett's  meal  and l e a c h i n g  o r more e f f e c t i v e  in  based  losses,  promoting  121 CHAPTER 5:  ZOOPLANKTON  HARVESTING  5.1 I n t r o d u c t i o n ,  The  harvesting  important  recent a  and  sciences.  area  of  5.2  significant  active  literature  fishes? food  of  hiqh-quality  WHO,  1973);  and  billion  a  4 of  food  also  oceanographic  status a  an  of  review  this  of  the  advangages of h a r v e s t i n g s e a f o o d  addressed  average  about  day  24%  people.  metric tons  c o u l d be a c h i e v e d by  decline  in fertility  A,D.(Frejka,1973).  Seafood  fish  requires  food  35-40 qrams  diet  (FAG  p r o d u c t i o n o f 70  and  million  requirements  Ricker(1969b)  estimated  probably  per y e a r o f f i s h ;  20%  Suppose t h i s  A.D. billion,  The  provide  of  that  be i n c r e a s e d t o of  based  about  this  siqnificant  projected  t o a net replacement could  t o mankind's  of the p r o t e i n  protein.  5,9  commercial  increasing  f o r an a d e q u a t e  2000  be about  for  person  the sea can  usable hiqh-quality  t h e n would  in relation  potential  each  from  150-160 m i l l i o n  population  technology,  thus the present annual  the world's  increase  be  the  protein  furnish  is  present  i t  t h a n t h o s e o f most p r e s e n t  t h e s e a . The  m e t r i c t o n s can  on  and  p r o s p e c t s and  trophic levels  p r o d u c t i o n from  total  fisheries;  is  Review  requirements  about  indicate the  T h i s q u e s t i o n may  production  world  micronekton  area of i n t e r a c t i o n f o r  research  what a r e t h e lower  To  in  and  i s presented,  Literature  from  zooplankton  development  represents fishery  of  world  optimistically o f 1,0 35%  by  2000  of  the  122  world's 3%  minimal  of  it's  biological  and  a population  kcal/day tons  by  protein  p r o t e i n needs i n t h i s  2000  ft.D,  importance as landings  sea,  source  times  Many o f the nearing  increase  world's  or are  (Gulland,1971).  at  organisms  within  sufficient  motility  against  local  to  or  fish),  other  Takahashi,1973),  such  whose d i s t r i b u t i o n  fleets  the  of  protein  37%  in  6  fish  billion  t o grew i n  provided up  that to  two  fisheries for fin fishes  come?  readily  2-10  of  The  harvest  level  the a n t i c i p a t e d most  g r o u p e d as  the  be  considered  cm  (WP-4,1968)  their  position  promising micronekton as  pelagic  which  and  to  small adult  cephalopods  and  over  200  fishing  mile  such  (myctophids  large  euphausiids.  mm  (Parsons  small ocean  economic  Onion)  are  underutilized  and  euphausiids, currents.  zones,  grounds f o r t h e i r  Soviet  (eg.  fish  2  a s l a r g e c o p e p o d s and  have move  group i n c l u d e s l a r g e decapods  zooplankton  harvesting  million  about  sustainable  to  Penaeids),  the  3000  150  expected  i s the bulk  maintain  of the  (eg. J a p a n , and for  of  i s i n f l u e n c e d s t r o n g l y by  advent  curtailment  technology  be  range  small  Megazooplankton i n c l u d e  With  maximum  currents. This  and  on  levels.  M i c r o n e k t o n can  the  Sergestiids, lantern  can  about  i n proportion to population  where t h e n  stocks  only  (based  increase of  be  mankind's  production  megazooplankton.  can  major e x i s t i n g  the  From  i n seafood  underutilized  facing  of  the present  an  a population then,  increase roughly  or three  and  would r e p r e s e n t  The a  requirements  but  of 6 b i l l i o n ) . Landings of  per c a p i t a , assuming  (Bicker,1969b).  are  energy  situation,  nations  d i s t a n t water  developing stocks  as  the the  123 Antarctic stocks and  krill,  of  Euphausia superba  rayctophids.  Japan  have  micronekton  Such  already  and  sense  to  energy  standpoint from  efficiency, from  to that  trophic  supplied  in estimating  the  ecosystem  (eg.  be d e f i n e d  as:  as low  level,  E  the  trophic  levels.  between tuna)  and  fewer the the  5%  as  a trophic level  number  harvested  level,  active  of various  which  level, the  of  1974;  of  harvesting  ultimate  uses of  the  catches,  amount  of  energy  been  used  levels  of  an  production  (P)  can  E  can  primary  and  n i s the  in  the such  herbivore).  greater  On  the  as  harvesting at d i f f e r e n t  number  i s the  of  range  salmcn  Clearly,  i s the  other  trophic  oceans  between t h e p r i m a r y  the  the  costs  good  practical.  amount o f  the  carnivores  overall.  enter  is  the  trophic  more e f f i c i e n t  relative  efficiency.  for  BE*  of t r o p h i c l e v e l s  and  as  of  t h i s sense  a planktonic  p h y t o p l a n k t o n t o man  considerations  Norway  i t makes  i s a c o n c e p t which has  pelagic  (eg.  trophic  as  fisheries  to the  ecological efficiency  30%  about  oceanic  Komaki,1957;  ratio  change i n biomass a t  available f o r harvest, from  the  T y p i c a l l y , values  (for  nations  a trophic level  P =  is  (eg.  S c h a e f e r , 1965) . I n  annual  fishing  of e c o l o g i c a l e f f i c i e n c y  production  where B i s t h e  widespread  1976).  defined  extracted  the  nearshore  megazooplankton  harvest  Ecological  prominent  developed  0 m o r i , 1 9 6 9 ; Wiborg,1966;  From t h e  , and  or the  level  and  production food  hand,  process,  chain  practical such  as  trophic levels  and  decrease the o v e r a l l  transfer  124 The of  first  serious s c i e n t i f i c  plankton  harvesting  Hardy(1941),  Ruud{1932)  that  " i f the  become  a  marketing  practical  richness  plankton "there  filtering  i s l a n d s or i n the  currents areas  as t h e  large nets the  tidal  time  h a r v e s t i n g . He  i t  special  s h i p s to h a r v e s t  seas".  Despite in  inadeguate  two  f o r economical  Jackson(1954)  than sea.  were t h e t e c h n i c a l His  report  procuring  a l s o mentioned  between  suitably  possible  use  for testing  so t h a t t h e y Hardy  richer  harvesting  d r a w b a c k s were more f o r m i d a b l e  of  harvesting f o r s e v e r a l years.  that a  located  of  tidal  feasible  to  employ  of the  polar  i d e a of a  plankton were  1956).  engineering  in  as  that  concentrations  obstacles to a  interest  of of  might s w i n q  plankton  (Hardy,  that  use  f u r t h e r remarked  work, the as  the  and  plankton  problems of e x t r a c t i n g p l a n k t o n  dampened  some  of operating economically  shelved  contended  l o c a t e d or  rate  economically  the s t i l l  was  to  d e s c r i b e d the s u i t a b i l i t y  y e a r s of survey  Scotland  above  of S c o t l a n d  would be  is  of g r e a t l y i n c r e a s e d  ) must be  the  moored f r o m a n c h o r c h a i n s  in  concluded  estuary".  upon  west c o a s t  3  flow an  Clarke(1939),  Clarke(1939)  However, he  c u r r e n t s change d i r e c t i o n .  "perhaps  fishery  of  enlarged  i n plankton  such  tidal  prospects  a commercial s c a l e  the  possibility  entrance  by  e i t h e r areas  feasible".  the  Hardy (1941)  on  0. 1 g d r y wt/m  some  plant i n  plankton  f o r making  economically be  initiated  J u d a y (1943).  reality,  found  might  and  of  ( g r e a t e r than  method must be  sere  d i s c u s s i o n s on t h e  commercial  economic fishery from  the  plankton  125 5.21  Methods o f Before  Plankton  returning  t o e x a m i n e some o f The or  to  the  involves streaming d e p t h by filter  i t may  and be  the  then  to  are  large  There  be  the  degree  of of  the  can  to s t r a i n  meshes. A  net  more  time i n c r e a s e s  the  of  the  around the hauled  this  in relation  net  tc  net  drop  hand  or  action  to  A p o s s i b l e s o l u t i o n i s t o monitor  winch.  might  During  is  due  reduce and  unproductive  time.  rate are  o f tow  heavier  makes h a u l i n g  filterinq  filterinq  of  catches  drastically  period  be of  t r a w l method.  Consequently,  lenqth  is  collar  by  r a i s e d by  may  towing  frequent.  at  (5 m o r more i n  the codend i s  to the  the net  but  i t  retrieving  entire unit  body  seams, a l i f t  codend and  of  of  d a v i t o r drum i s a v a i l a b l e  is fitted  net  optimum  towing  d e c k . A l t e r n a t i v e l y , when  conditions affectinq choosinq  the  the  I f only  shortened  clogging,  nets,  to leave  lowering  warp, and  net  conical  cycle  line),  l a r g e r nets  drawbacks  efficiency  handlinq  problem.  on  the  serious  (towing  r e t r i e v e d and  p u l l e d over the  of the  variable,  For  line  be  catch  clearing  Since  smaller  towed  familiar  surface,  in the  s u i t a b l e crane,  line  towing, f i l t e r i n g  warp  aboard.  the  at the  hauling  throttling  are  to clogging  the  emptied.  a  raise  w e b b i n g may  catch,  net  more p r a c t i c a l  a  as  out  e n t i r e net  codend. T h i s  winch  the  codend. For  unless  hauling  hauled,  the  from the rinsed  paying  r a n g e from  i s by  beam t r a w l s . I n a l l c a s e s t h e  catch  so  plankton  harvesting.  and  submerged  the  plankton  otter trawls  lifted,  for  methods o f  designs  to  length)  suggested  worthwhile  net  fishing  depth  the  is  Plankton  operation to  t o Jackson's arguments, i t  most common method o f c a t c h i n g  trawl.  nets  Harvesting  often  a  filtration  hiqhly  substantial efficiency  126 with  a telemetered  flow  meter. When f i l t r a t i o n  efficiency  falls  t o o low, the n e t i s h a u l e d . a major advantage harvesting plankton the  unit;  patches  best  this over  fishing  possible.  of  (eg  permits  depth  of  f o r day  mobility  of the  and e x p l o i t a t i o n o f  operation.  or  net avoidance  euphausiids  i s the  the location  a l a r g e area  In a d d i t i o n ,  micronekton  trawling  Selection  of  night operation i s also  by l a r g e  and s e r g e s t i d  zooplankters  and  shrimps) i s reduced  when l a r g e t r a w l s a r e u s e d . A modification pumping  system.  of  the  The  c o n t i n u o u s l y withdrawn  trawl  from  A water s e p a r a t o r o n b o a r d effluent  method  filters  t h e codend removes  the  pumping r a t e .  of  filtration  catch  likely  20m  likely  2  and  a  towing  speed  would  t o be l e s s than  t h e pumping  be  beam-trawl which  i s  system.  the  water  be v e r y s i m i l a r  is  The f l o w  10  m /sec 3  of  having  a  net  less  (10»  1/sec).  o f 30 cm, t h e pumping  than  4000 2.5%  gal/min). of the  p a t t e r n i n t h e n e t would  t o t h e c o n v e n t i o n a l l y towed n e t ; c l o g g i n g  c o n t i n u e t o be a p r o b l e m . O t h e r  difficulty  by t h e maximum  0.5 m/sec, t h e maximum  250 1 / s e c (about  capacity  c a p a c i t y o f the net.  would p r o b a b l y the  from  F o r example, i n a s y s t e m  rate i n the net  Consequently filtering  catch  i s limited  However, even w i t h a s u c t i o n p i p e d i a m e t e r is  the  by a pump o r l i f t  the  c a p a c i t y o f a pumping s y s t e m  economical  rate  is  f o rprocessing.  The  opening  trawl  manipulation  disadvantages are  and t h e d a n g e r o f p e r m a n e n t l y  damaging t h e s u c t i o n p i p e by k i n k i n g . another Hardy (1941),  method  of  plankton  i s the s t a t i o n a r y  harvesting,  swing net.  suggested  by  F o r use i n areas  with  127 strong the  tidal  currents  advantage  and a b u n d a n t z o o p l a n k t o n , t h i s method  of  self-orientation  o p e r a t i o n a l l a b o u r . One to  15  anchored  involved  inverted stretched  relative  larger  longer  Shortcomings of  harvesting surface  artificially  reduce  the  swing  and  certain  induced  absence  lower  this  for  be  of  than  Shropshire(1944)  plankton apparatus  screens  and  from s e a w a t e r overcomes  restrictions.  can  be  netting  can  be  occurrence  of  and c t e n o p h o r e s , method  are i t s  in i t sdaily  highly  catch.  organisms  is  swarm  life  near the  history  impractical  for  (eg  when t h e  o r i n deep s u b s u r f a c e l a y e r s . harvesting  swarms  for  naturally  but  or  or mechanical  catch  rate  or t r a w l i n g .  is  In the  i s impractical. and e x p e r i m e n t e d w i t h a s y s t e m nozzles  on  continuous  problem  The s c r e e n drum  the  seining  spray a  occurring  i s by h a n d - o p e r a t e d  purse  devised  the  effective  which  their  method  o f swarms, d i p n e t t i n g  rotating  duties  intervals,  marine f o u l i n g  micronekton  stages  However,  method  can  n e t . The e g u i p m e n t i s i n e x p e n s i v e ,  generally  net  10  nets  the  s u c h as medusae  method  populations are dispersed another  to  low  e t c ) must be c o u n t e r a c t e d .  zooplankton  euphausiids).  and  The o n l y  the  coarser  (weeks o r months)  seining  during  a  and t h e h i g h v a r i a b i l i t y  periods,  purse  clogging  also,  mouth  1976).  the net a t r e g u l a r  reduce  plankters,  ( b a r n a c l e s , mussels,  dip  (Wiborg,  emptying.  immobility  The  To  a c r o s s the net  the catch.  Over  nets  morning.  undesirable in  swing  after  currents  fisherman i n a small v e s s e l can tend  a r e c h e c k i n g and e m p t y i n g  u s u a l l y each  to  has  of  to  filter basis.  clogging,  must r e m a i n  partially  and  collect  Although i t  of  his  has o t h e r  emerged  from  128 the  water f l o w i n g  washing  by  the  into  i t in  spray  jets.  order  to  T h u s , the  permit  effective  drum must  be  fixed  w a t e r s u r f a c e , where p l a n k t o n  concentrations  are  than  For  operation  at  subsurface  Shropshire's from  the  device  drum  h a r v e s t i n g by there  this  a  position  by  cost  of  unit  would  r e q u i r e a conveyor to  processing  plankton  operation  the  on  of  a a  unit.  An  reqular  flow.  compared  p r o d u c e a low  to  plackton  the  choice  distribution  for a particular  and  behaviour  o p e r a t i n g c o n d i t i o n s , and  on  5.22  f o r Plankton  Operating  Conditions  Returning  to the Jackson  conditions  which  low  First,  he  argured  f l u c t u a t e widely Paton,1947;  knowledge o f t h e is  impossible  given for  with  region, detecting  that  time,  Riley  (Note  predict  harvestinq  will  plankton  the  resources  available.  a  number to  of  operating  be o b s t a c l e s  to  below.  plankton and  population  depth  Gorgy,1948)., F u r t h e r ,  their  o r swarms o f  densities  ( H a r v e y , 1950;  Hardy without  populations  i t  magnitudes o r d e n s i t i e s i n a  that during that period electronic  layers  capital  t a r g e t s p e c i e s , on  mechanisms i n f l u e n c i n g p l a n k t o n to  a  on  considered  place and  from  Harvesting  Report,  discussed  the  depend  financial  Jackson(1954)  economic h a r v e s t i n g a r e  and  the  where  investment.  locality  of the  economic  the  I n summary, t h e r e a r e s e v e r a l e f f e c t i v e methods o f h a r v e s t i n g ; the  sea,  justify  addition,  r e t u r n on  at  to harvest  relatively  the  lower  localities  basis  In  with the  remove  few  at  often  obstacle to  machine d e s i g n e d  usinq t i d a l  likely  continuous  method i s t h a t t h e r e a r e  fixed  rate  would  to  i s enough  continuous  levels.  back  plankton  devices  were u n a v a i l a b l e ) .  129 Consequently, plankton  would  Since and  s e a r c h i n g time  to locate  he e x c e s s i v e l y  1954, h i q h  concentrations  sonar  and e c h o s o u n d e r s  g r e a t e r ) have been i n t r o d u c e d which a r e c a p a b l e such  Pieper,1970)  and c o p e p o d s  surveys employing  as  euphausiids  these  vertical  migrating  0mori,l969). operations, subsurface the  althouqh  the  Steele,1974; quantitative  predict  quite reliably  zooplankton  layers  better  are  not  certain  reqions  For  example,  and P a c i f i c  finmarchicus  applicable to and  i s possible t o  Euphausia  Off  the  accordinq  d e n s i t y of plankton a  time  Koraaki {1967)  d u r i n q s p r i n q and summer  suqqested  (eq  aqqreqations  west  o f t e n swarms n e a r  more s e r i o u s p r o b l e m  Clarke(1939)  of  far  of has  pacifica  c o a s t a l r e q i o n s o f Japan i n  Calanus  Thus  i t  t h e o c c u r r e n c e o f dense  Norway,  t h e averaqe  previously,  so  yet d i r e c t l y  t o s u r f a c e water temperature.  that  than  developed  relation  A second,  and  understood  models  micronekton.  a f t e r n o o n and e v e n i n q  harvesting  controllinq  in  Sea o f J a p a n  1970;  are invaluable f o r locating  t h e s e a s o n a l s u r f a c e swarminq  the  and  o f p l a n k t o n abundance i n r e a l  this,  and  Pieper,  their  n e t s . Today, t h e p r o c e s s e s  Patten,1968)  Despite  and  our  determining  mathematical  prediction  Plankton  for  are  space.  alonq  sounders  and  increased  and  sampling  plankton o r micronekton  production  Bary  distributions  (Bary  scientific  high frequency  plankton  described  and m i c r o n e k t o n  f o r towinq  1969;  have q r e a t l y  (100 k h z  of detecting  ( B a r r a c l o u g h e t ajL. , 1969).  behaviour  During  best depth  (Beamish,  instruments  knowledqe o f z o o p l a n k t o n  of  h i q h f o r economic h a r v e s t i n q .  frequency  zooplankton,  is  hiqh  of  the surface i n  (fliborq, to  coast  1976).  Jackson(1954)  p o p u l a t i o n s i s v e r y low.  maximum a v e r a q e  d e n s i t y o f 0.1  130 g/m  3  g/m  3  dry weight dry  while  weight  calculations, harvesters  Jackson  and  Cashing  { i n Jackson,1954) c o n s i d e r e d  to  a  be  used  0.01  g/m  a  "rich" value  for  3  concentration.  of  0.1  g/m  In h i s  for  3  0,05  mobile  stationary harvesters i n t i d a l  estuaries. The  above f i g u r e s a r e t o o c o n s e r v a t i v e a c c o r d i n g  surveys  of  detected  copepod  (0.3  g/m  extensive  concentrations  dry  3  marine r e g i o n s .  o f about  supported  concentrations  of  by  whales.  B. C.  a b o u t 2.5 g/m  zooplankton  the  Parsons,1972).  food  inlets,  weight  Along  a r e present  have  the  west  observed  in  surface  coast  (Wiborg,1976).  In  the  concentrations  of  10 t o 16 kg/m  ( B u r u k o v s k i y , 1967; basis  at  plankton  least,  Southern  there  or micronekton  Economic  and e x p l o i t a t i o n  Another  problem  3  d r y weight harvesting  o f such  seasonal areas  planktivorous f i n concentrations of (Pieper,  Norway,  weight  have  spring  on  often  and summer  Euphausia  Thus,  in  Calanus  superba  wet weight have been  concentrations  Jackson(1954).  "average"  extensive  are often extensive regions  o f 0.1 g/m  r a t h e r than  during Ocean,  3  sampling  over  of  wet  S a s a k i e t a l . . ,1968).  "average" f i g u r e  location  patches  weight  and n e t  recorded  3  wet  3  dense  of  been  e t al._ (1969)  that  euphausiid  c o n c e n t r a t i o n s a s h i g h a s 6 t o 24 kg/m been  g/m  recent  Ocean i n s p r i n g . T h e s e  reguirements  coastal  dry  3  Pacific  Klumov's (1961) c o n t e n t i o n  as i n d i c a t e d In  1.5  w e i g h t ) by 200 k h z e c h o s o u n d e r  during transects of the subarctic results  Barraclough  to  reported  a  seasonal  i n which t h e  a r e much h i g h e r  than  the  u s e d by C l a r k e (19 39) and depends  on  dense a g g r e g a t i o n s  the or  prompt patches  concentrations. cited  by Jackson{1954) i s t h e v a r i a t i o n i n  131 zooplankton and  catch composition  zooplankton  given  harvest  in  the  season  the  very  consistent since  for  a  uniform  single size  comprised  species  Further  caught with During can  hinder  nets  catch  o f f the  harvesting  or s p o i l i n g  the  J a c k s o n (1954)  also  of plankton  the  protected  winter,  with  B.  C,  operations  Jackson's  are  are  other  Norway,  surface  the  that  coast  the early  (Wiborg, sometimes  by  of  spring final  conditions  densities  harvesting.  Poor sea  fishing  clogging  may  as  disrupt  conditions,  bad the  though,  operations.  Seasonal  many c o n v e n t i o n a l  fisheries  of weather, i n  where p l a n k t o n f j o r d s or  regions  h a r v e s t i n g has  inlets  have  moving t o more e x p o s e d and  such  fisheries.  adverse e f f e c t s  waters of  c a l m e r months of  and  finmarchicus  the  along  p o t e n t i a l plankton  and  months  diatoms  as  Norway  relatively  medusae, c t e n o p h o r e s and  i n abundance a l s o a f f e c t s  as  select  night.  plankton  t o most t y p e s  reduce the  to  at  variation  To  often  i n s p r i n g and  euphausiids  near  stated  continuity  w e l l as  coast  is  commercial  paeifica In  a  catch.  s e a s o n s o f low  detrimental  the  Calanus  operations  weather and  are  tend  winter  observation).  Norway c o a s t ,  months, t h o u g h ,  area  region,  and  Euphausia  of  phytoplankton  towing speed  fall  especially  x  i n an  of Georgia  along  entirely  Calanus  summer  of  of  r e l a t e d s p e c i e s of  the  (personal  commercial zooplankton  1976).  Strait  entirely  almost  composition  closely  during  mixing  However, i n p r a c t i c e , d u r i n g  mesh s i z e s and  catches  euphausiid  summer i s  catch  species or  almost  the  catch.  range. I n t h e  zooplankton  and  been  such  commenced, fished  in  waters d u r i n g  the  summer.  o b j e c t i o n to plankton  h a r v e s t i n g was  that  132 "not some  a l l forms of are  plankton  toxic,  harvesting  a r e p a l a t a b l e o r even  presenting  when  we  very  have  o f t h e community".  harvesting  would  gear  from  can  be  sea  w a t e r . On  Harvesting  of  This  euphausiid  bounded  t o the north  by  not  i n temperate  seas.  November t o l a t e  Euphausia  frigid  and  horizontal  the  distribution  Rind  and  mesh  Zooplankton  age  in  Except krill  all  sectors  surrounding  of  the  Antarctica  and  convergence zone; i t does  d u r i n g t h e summer months spend  perimeter  most o f t h e i r  of the  packice  is  a s s o c i a t e d with  from  lives at  0  (Marr,1962;  summer,  the cold  their  waters of  W e d d e l l D r i f t s ( M a r r , 1 9 6 2 ) . S u r f a c e swarms  with  as  have  been  also at  night  acoustically their  one  of  harvesting  and  Makarov, 1969). In open w a t e r d u r i n g  10-16 and  kg/m (Burukovskiy,1969) 3  visually  bioluminescence  ( I v a n o v , 1969; 1970) . The of  of a l l t y p e s  superba  Antarctic  March, t h e  d e n s i t i e s as h i g h  when  the scale  appropriate choice of  lives  waters  C beneath the i c e or a t the  located  of  large  plankton  Micronekton  species  Ocean, t h e  East  bulk  Operations.  Southern  the  assumed t h a t  contrary,  through  Present  Antarctic k r i l l ,  Shevtsov  has  and  fisheries.  5.231  live  the  highly selective  Examples  He  in  knowledge  involve unselective f i l t r a t i o n  s i z e s , as i n c o n v e n t i o n a l  5.23  problems  insufficient  composition  plankton  serious  nutritious,  group  swarms a r e  usually.  The  s e v e r a l meters t o s e v e r a l t e n s of  in daylight is mobile  and  sufficiently aggregations  diameters  intense of  krill,  o f swarms r a n g e  m e t e r s . ,. L a r g e  areas  from  spotted  133 with  thousands of  great  i n t e r e s t commercially(Burukovskiy,1967).  The  region  fishery, Scotia and  smaller  which  according Sea  and  to  the  swarms, known as  shows the  area  Soviets,  in  the  Sea ( S h e v t s o v e t taken  vicinity a l . , , 1969)  in catches  The  from  formation  cyclonic  Sasaki  oceanic  et et  vicinity  al.  and  into  flow  the  vertical to  daily  h i s t o r y stage.  history  Two  often  the  e f f e c t s of  et  (20-36  to  Scotia mm)  be  are  associated  and  the  a l . . ,1969;  seasonal  scientists  often  found i n  the  covergence zones of sea  Euphausia  cycles  the  mounts  Ivanov(1970) r e l a t e s  generalizations;  description  of  Elizarov,1971;  p r e d i c t i o n s can of  with  centres  oceanographic c o n d i t i o n s  reliable  A brief  the  tend the  n e a r i s l a n d s and  above  distribution and  in  Japanese  of these c u r r e n t s .  against  swarming i s n e e d e d b e f o r e  according  and  i n the  for  The  Soviet  gyrals  the  of  swarms(Ivanov,1970) .  of  which  research  chains  more j u v e n i l e s  Bogdanov  Weddel D r i f t s ,  of  commercial  (42-60 mm)  swarms a p p e a r s t o  West Wind and  results  krill  swarms a r e  persistent  a  are  A t l a n t i c sector  a l . ,1968) b e l i e v e t h a t  alter  for  back e d d i e s o f c u r r e n t s  ,1969;  fields"  A n t a r c t i c P e n i n s u l a (Shevtsov  island  while  g y r a l s (Buud, 1932).  (Avilov  i s the  Adult  of  of the  a r e a s of convergence,  promise  around t h e  Makarov,1969; I v a n o v , 1 9 7 0 ) .  swarm  life  best  "feed  which  be  further on  made.  superba are  krill  varies  dependent  of  the  krill's  eggs  per  adult  on  life  follows.  thousand  (Bargmann 1945;  to  10,000  Nemoto,1968) a r e  krill  spawned d u r i n g  early  female  summer  in  134 shelf  and  first  oceanic  n a u p l i u s which  waters.  They s i n k w h i l e  hatches  a t d e p t h s o f 100 0 m o r more.  ascent t o the surface the l a r v a e nauplius,  metanauplius  and  furcilia  I stage, the larvae  feeding  on p h y t o p l a n k t o n  stages  (> 20 mm)  during the  Marr(1962)  with  are  i n the  the k r i l l  40  summer  i s  the v e r t i c a l  m.  when  the  surface  below 40 m ( S h e v t s o v  The  they  30 mm).  42-60  exploited juveniles fished stages  Until  begin Shevtsov  mm, during  22 mm  m  where  furcilia i s  rapid  i s reached i n  a s two  three  to year  years,  o f j u v e n i l e s and  stratification  with  swarming i s n o t p r e s e n t ; t h e  the  phytoplankton-rich  waters  while a d u l t s g e n e r a l l y predominate  are harvestable  t o swarm a t t h e s u r f a c e a s l a t e e t a l . . (1969) s u g g e s t  which w i l l the  that the k r i l l  first  that  half  of  summer  the  summer,  juveniles krill  s h o u l d be while  f e e d i n g and growth  a t t h e end o f t h e summer. The J a p a n e s e  from  adult  d i e b e f o r e t h e n e x t summer,  which a r e c o m p l e t i n g  over  By t h e  According  takes  Age  second  e t a l . . ,1969).  S o v i e t s have f o u n d  time  in  40 m t h e r m o c l i n e ,  Growth  distributions  to the thermocline.  observed  100  the separate sexes  In  (about  upper  During  the  stages.  Bargmann,1945).  o c c u r r i n g i n the fourth year.  the  i n t o the  They s p e n d t h e l a t e  breeding  above  all  the  t h a t maturation  j u v e n i l e s a r e most a b u n d a n t  be  in  upper  mature i n t o  Ivanov(1970) contends  depth  of  calyptopis  proceeds.  year(Ruud,1932;  adults are related  the  three  through  t h e summer a s a body l e n g t h o f a b o u t first  olds.  mostly  progress  developing  the  should  have c o n s i d e r e d  20 mm t o be h a r v e s t a b l e ( S a s a k i e t a l . , 1968).  recently  the f i s h e r y  for  Antarctic  krill  has  been  135 experimental,  involving a small  O n i o n , J a p a n , and in  the  southern  were  by  West Germany. S o v i e t summer o f  modified  fish  of  70  t o n s was  meal p r o c e s s .  livestock  feed  In  out  ingredient.  exploratory  S h e t l a n d s and the a  1968  i n the  size  depths,  o f 6 mm",  The  accompanied  although  about  2  was  t o n s per Soviets  in  trawl  which  for  krill  ,1973). The  annual S o v i e t  FAO  unofficial  Yearbook  reports  that  pump  the  trawler  "Muksun"  krill  meal by  success  two  smaller  the  area  and  from  the  of  could  upper  136  10  m.  a  10-12  the  South For  tons  at  from  codend  different  Catch  rates  otter-  (Lyubiraova  et  not  been  Statistics,  a b o u t 20,000 t o n s was  t/h.  mid-water  t/h has  a  trawlers  with  fish  a  research  a maximum r a t e o f 7  krill  Fishery  of  trawl  developed  yielded  of  as  Makarov,1969).  "krill trawl  catch  of  a  hour, with  has  harvesting  fish  a catch  this  have  at  began  and  with  by  Soviet  krill  f o l l o w i n g summer t h e  which u s e d  the c a t c h  on  tons of  tested  harvesting  More r e c e n t l y , t h e  the  was  11  S c o t i a Sea(Shevtsov  fishery  most o f  averaged  in  into  season, Ivanov(1970) r e p o r t e d  10-day t r i a l  mesh  1964-65 a b o a r d  product  v e s s e l "Akademik K n i p o v i c h " carried  trawls  processed  The  research  from t h e  1961-62. E a r l y a t t e m p t s fish  u n i t s ( B u r u k o v s k i y , 1967) . a catch  number o f s h i p s  but  caught  a.l  ±  reported there in  are  1974 {  SCAR/SCOP., 1977) .  The  Soviet  human c o n s u m p t i o n fluids in  and  trays  catch by  separating and  is  processed  pressing the  deep f r o z e n .  ingredients  krill,  coagulated  for  and  a protein  cooking  paste,  Food p r o d u c t s  paste i n c l u d e "shrimp b u t t e r " ready-to-eat  the  into  the  extracted  which i s then  derived  a melted cheese,  salads,  paste f o r  stuffed  from  packed  the  as  eggs and  krill  well  as  stuffed  136 f i s h . . apparently the k r i l l  paste  market, but t h e r e are p r i c e  p r o b l e m s ( L y u b i m o v a e t al..  Atkinson,  personal  Japan Antarctic  has  fishery  the Tokyo U n i v e r s i t y and  Foss  Sea  experimented  areas(Sasaki with  a  and  patches  a]U  was  130  deep-frozen  midwater  trawl.  surface-midwater was  reported  as  (FAO,1975;1976).  purse  1964-65  potential  for  150  Koyama otter 643  seine  without  was  also  commercial  the  for  i n the  The  1974  The and  large  superba frequent  between  of k r i l l ,  in  an  a more  1000  fishing  the which  efficient  tons  catch  in  1975  corporations in  development  krill  by  inefficient  Japanese k r i l l  to the  Antarctic  application.  and  developed  but  a r e a bounded  59 t o n s  taken  t h e i r commitment  fishery  tested.  fiuphausia  south  1973,  was  two  pump  Comparatively  trawl f o r k r i l l .  Recently,  a fish  were c o n s i d e r e d p r o m i s i n g ,  E. I n  in  Haru" o f  initially  et al(1974)  tons  an  They  cruise.  storage,  of  a l . . ,1968) ,  swarms were n o t e d  E and  J a p a n h a v e announced commercial  C.  D'Orville  were r e g u i r e d f o r  krill  of  , 1973;  t o the  n e t , w i t h and  technigues  the  of  the S o v i e t  made a c r u i s e  S t o the n o r t h , the p a c k i c e to  meridians  the  (1968) r e p o r t e d o b s e r v a t i o n s on  during  occurrences 61  seining  inprovements  et  sguare  pumping  et  investigated  of F i s h e r i e s  t o the codend; a  Ozawa  on  s i n c e 1964-65 when t h e " O m i t a k a  attached  further  been a c c e p t e d  communication).  seriously  krill  has  (Fishing  of  a  News  International,1976).  In direct  Japan, use  Crustacea.  f r o z e n whole k r i l l in  traditional  Research  on  has  ways  found  a ready  applied  to  diversification  of product  market  similar use  is  for small also  137 u n d e r way  (PAG  West 1975  Germany  southern  landed  250  krill  1974).  entered  the  summer when t h e tons  successfully the  Bulletin,  of  developed which t h e y  Antarctic  research  ship  krill.  German  food  sauces,  s o u p s and  "fish  stick"  are pressed giant  of  started  together(T. the  pet  fish  t o market a new  whole f r e s h f r o z e n k r i l l  The  but  on e s t i m a t i o n s o f t h e krill-eating stock and  packets  Parsons,  product, and  5000 m i l l i o n  krill  Lyubimova  et  al..  variety  approaches.  of  estimated baleen  annual  w h a l e s and  removed,  communication).  The  has r e c e n t l y  F l a k e s , which  krill  baleen  lists  has  sources  not  been  which  rely  w h a l e s and  other  Klumov, 196 1}.  The  standing  i s between 800  production  been  and  and  million  Ruud,1964;  100  150  F i s c h e r , 1974; place  million  c o n s u m p t i o n by  p a s t and  present  by  predators,  1970;  Tomo  the  tons,  include  krill  the  M c Q u i l l a n , 1962;  methods  other  These  and  of  Mackintosh,1966;  Omura, 1973;  between  biomass  made (eg.  M a r s c h o f f , 1 9 7 4 ; B v e r s o n , 1976) . Most e s t i m a t e s yield  chitin  tons.  , 1973;  harvestable  include  have been p u b l i s h e d  to these  have  Shevtsov,1963; Jonsgard  krill  personal  of the Antarctic  Numerous e s t i m a t i o n s o f t h e Antarctic  from  with  amount consumed by  metric  paste  C a l a n u s among i t s i n g r e d i e n t s .  estimates  according  have  to crab(Fishing  from t h e  Tetra K r i l l  the  Herwig"  of k r i l l ,  a n i m a l s ( P e g u e g n a t , 1958;  of k r i l l  in  technologists  food i n d u s t r y , TetraWerke,  potental production  measured d i r e c t l y  "Walther  c l a i m t a s t e s very s i m i l a r  i n which  fishery  a sandwich  News I n t e r n a t i o n a l , 1 9 7 7 ) . O t h e r p r o d u c t s a  krill  and  annual  b a s e d on  tallying populations  estimation  of  a  the of the  138 proportion  of  primary  production  e x t r a p o l a t i o n from c a t c h  rates  Although  the  estimates,  i t appears that  yield  the  of  results  same  are  J.W.  S.  Antarctic  on  of  whaling  region,  combined  British  into k r i l l , plankton  very  and  hauls.  approximate  has  weight as  a  potential  that  of a l l the  (Burukovskiy,1967).  facing  a  major  A n t a r c t i c oceanographer,  eloquently  and  which  and  difficulties  great  has  in  sugerba  s i z e by  stocks  The  Barr(1962),  restrictions  indirect  considerable  harvesting operation.  krill  EuEhausia  order  presently exploited fish  There  are  of  incorporated  stated  oceanographic  would a l s o a p p l y  the  natural  operations  in  to a large scale  the krill  fishery: A v a s t a r e a o f t h e A n t a r c t i c Ocean, i n v o l v i n g much of the r i c h e s t o f the whaling qrounds, has f o r s i x v i t a l months, from June to November, never been visited by our v e s s e l s , n o r i n t h e n a t u r e o f t h i n q s i s i t e v e r l i k e l y t o be. I n d e e d since the hiqhest latitudes can o n l y be a t t a i n e d i n J a n u a r y , P e b r u a r y and March, i t i s c l e a r t h a t much o f t h e r e q i o n s o u t h o f t h e 6 5 t h p a r a l l e l , and p r o b a b l y e v e r y w h e r e south of the Antarctic c i r c l e , an enormous c o a s t a l b e l t t h a t w i l l be demonstrated later to be of major importance to the whalinq industry, i s virtually c l o s e d t o n a v i q a t i o n f o r a l l but 3 months of the year—an accident of qeoqraphy that w i l l always present a problem t o A n t a r c t i c oceanoqraphers." M  Thus l a r q e s c a l e southern l l i  harvestinq  summer s e a s o n which  (1968) have p o i n t e d  out  would  shiftinq  to  Of  particular  ability krill  to detect  is likely  population  seems  to  as  occur  the  weather t o o .  low  pressure  areas  importance,  a n d / o r p r e d i c t where and  to occur,  to  ways f o r s h i p s t o a v o i d  by  krill.  limited  i n c l u d e s bad  rouqh seas caused harvest  be  only  a small  Sasaki  so  continue  will  be  the  when t h e swarminq  fraction  i n dense a q q r e g a t i o n s  et  excessively  and  thouqh,  short  of at  the one  of  krill time.  139 This  behaviour  the  food  pyramid  allowance  f o r such  krill  acts as a natural buffer against in  krill  are a keystone.  c o n s i d e r a t i o n s , t h e projected annual  fishery  krill,  interested  treaty  nations(Anonymous,1977a).  i n exploitation  of the k r i l l ,  the  Australia,  planned  meeting  have  1978 t o  additional  up  nations  a  and  draft  regime  international  t o p a r t i c i p a t e i n the convention  first  time  international  controls  Atlantic  Norway  and  i n Canberra f o r to  decide  organizations conference. will  be  what  will  This  be  marks  placed  on a  copepods  and  krill,  Calanus  finmarchicus  MeganYgtiphanes n o r v e g i c a , Since  copepods  about has  1960, a s m a l l - s c a l e , e x p e r i m e n t a l been  Norway(Wiborg,1976). finmarchicus Norwegian  developing The  migrate  in  principal  which g e n e r a l l y h a s two  w a t e r s ( W i b o r g , 1954) .  In  w e s t e r n Norway, t h e o v e r w i n t e r i n g V,  nations  t h e U.S.S.R. ,  U.K.,  and  the  before the species i s nearing o v e r e x p l o i t a t i o n .  5.232 N o r t h and  draw  a preparatory  by  The  including  S t a t e s , West Germany,  fishery  of  international  i s being arranged  Japan, t h e United  the  y i e l d of  an i n t e r n a t i o n a l c o n v e n t i o n t o  r e g u l a t i o n s f o r t h e new f i s h e r y  invited  Making  i n t h e order of s e v e r a l tens  o f t h e d e v e l o p m e n t o f a major  f o r the Antarctic  Antarctic  early  of  o f tons(PAG B u l l e t i n , 1 9 7 4 ) .  In a n t i c i p a t i o n  13  the  t o man's h a r v e s t i s s t i l l  millions  draft  which  the c o l l a p s e  to the surface i n l a t e  fjords  species  fishery f o r  of  taken  generations  i s Calanus  per  c o a s t a l and s h e l f  Calanus  western  year  waters o f  , as copepodite  February;  they  in  stage  s o o n mature a s  140 adults  and  breed.  copepodite often the  stage  V i n late  a maximum i n t h e coast  of  b i o m a s s may second  develop  is  medusae,  often  stage  V  April  the or  later of  March  May,  spawning  a t which t i m e  i n May  Calanus  plankton(Wiborg,1976).  or i n e a r l y  other  of  the  in  from  the  deeper water b e f o r e s t a r t i n g  late  the  stock  by  plankters, especially  c l o s e t o t h e c o a s t (Wiborg, 1976).  individuals  plankton  July-August,  harvestable  neritic  Along  June. Although  peaks i n biomass  contamination  reach there i s  Norway, t h e s p r i n g maximum i n  c l a d o c e r a n s and  f j o r d s and  from  biomass o f  northern  generation  there  the  Progeny  The  in  copepcdite  summer c o h o r t o v e r w i n t e r  the cycle  anew  in  the  in  following  spring.  The but  copepod  dense  fishery  aggregations  Norway, Wiborg has and  swarms w i t h  as red c l o u d s , surface often  i s based  or  of  observed  1-3  m long  below i t .  congregate  in fjords  are  During  this  Calanus local  and  phytoplankton,  and  is  finmarchicus  kg/m . The 3  0.5-1  m  in  and  bays  migrates  to the  carried  western  3-25  g/m  3  visible  diameter,  at  the  s h o a l s of  fish  such  swarms,  a f t e r n o o n and  evening.  surface  into  small  swarms a r e  containing  during the  of  Off  x  of  F l o c k s of s e a b i r d s and  most o f t e n o b s e r v e d time, Calanus  exploitation  concentrations  d e n s i t i e s o f 6-15  just  which  upon t h e  the  to  inlets  feed by  on  tidal  currents(Wiborg,1976).  Many t y p e s including nets  conical  using the  widely  of nets  used  plankton  parachute at  have been t r i e d  i n the copepod  fishery,  n e t s , o t t e r t r a w l s , beam t r a w l s  principle;  the  p r e s e n t (Wiborg, 1976),  beam A  trawl  typical  is  and most  t r a w l has  a  m rectangular nylon  mouth, 4  fabric  meshes o f strength nets,  0.5  outer  produced x 0,8  of t h i s  it  m wide by  mm  and  is  often  meshes. The  shape o f  m codend  section.  The warp  attached pipe  m  and  ballasted  trawling  i s adjusted  bar  usual  and  two  as  with by  surface  t o 6-10  h o u r s . The  alive  longer  without  duration  The  above  accommodate sacrifice  the  and  the  frozen  25  procedure  appears  small  of  of h a r v e s t i n g  size  the  efficiency  the  about  net  30  mouth  on  a  mm to  c o n i c a l f o r the  10  single net  The  are  bottom  t r a w l ; depth  of r o p e between  of the  of t h e b a r .  m i n d a y l i g h t and  The  10  m  boats i n the f i s h e r y  i s prolonged,  sometimes  the  will  Calanus  i n the  net  boat. A f t e r towing shore  catch  from  towed  most o f t h e  fresher  at  undesirable  with  a t e i t h e r end  o f towing  therefore  f r e e z i n g onboard  i s drained  As  the  nets.  lengths  rationale i s that  and  prevent  i s towed  the  from 5 t o  a f t e r dusk.  f r e e z e r s , the  To  bottom s i d e s of t h e  in  the  coarse  stationary  b u o y s , one  although  p r o t e c t i o n from a  bridle and  has  swing  f r o n t 7 m and  i n the  woven  stationary  b a r r i e r net  changing the  surface  for  i s e i t h e r tapered  top  lead  depths of towing are  the  a  attached The  pipes  is  by  f o r the  long.  to s t e e l  a b o u t 0.5,  sufficient  trawl  beam t r a w l w i t h  120-150  netting i s a  medusae from s p o i l i n g  the  or c y l i n d r i c a l  catch  is  protected  codend,  lack  a porosity of  r e q u i r e s f u r t h e r support  as  The  f o r making c u r t a i n s ; i t  l a y e r o f n e t t i n g i n towed t r a w l s .  mouth  to  commercially  material  l a r g e r o r g a n i s m s such  top  3 m high.  than  up  remain  i f stored  i s completed  the  facilities.  to  be  vessels and  a i n the  product  compromise f i s h e r y at guality.  to the Long  142 hauls  are  often  plagued  filtering  efficiency.  monitored  f o rlong  depth  of  As  by the  to  the q u a l i t y  the  pressure  easily As  in  the  o f towinq  may  and a q a i n  in liquid  any  whales o r b a s k i n g frequency  fishery,  sharks  the  a calibrated  location  of  3  usually  ranqe.  seabirds,  the  with  of  siqhtinqs of the "red feed". distinctive  C o n f i r m a t i o n o f such  fine  result  siqns of  presence  nettinq from  over  plankton  net throuqh t h e  The volume o f a sample c a n be  cylinder  stationary anchored  nets,  A swinq  measured  t h e b o t t o m end.  concentrations  on  s u r f a c e and a l l o w e d are  suqqested  between  of  1-3  by  Hardy(1941), a r e  islands  where  by two o t h e r  buoys  attached  mouth; a s m a l l e r buoy i s t i e d  t h e c o d e n d . The n e t i s u s u a l l y t o orient  o f t e n tended  moderate  n e t i s moored t o a n a n c h o r buoy b y  and i s s u p p o r t e d  to t h e t o p bar o f t h e n e t ' s throttling-line  as  i n sounds o r  c u r r e n t s flow.  means o f a b r i d l e  nets  are  o r more{Wiborq,1976). The  tidal  they  harvestable  Visual  c a n d e t e c t and r e c o r d  zooplankton.  Reasonable catches u s u a l l y ml/m  under  the c a t c h i s  storaqe l i p i d s ,  be made by h a u l i n q a s m a l l p l a n k t o n  a p p r o p r i a t e depth in  of  and d i r e c t  echosounders  traces of subsurface can  suffer  by e x c e s s i v e p r e s s u r e a n d h a n d l i n q .  s u r f a c e swarms i n c l u d e f l o c k i n q  layers  are not  of towing o r  while  c o n c e n t r a t i o n s i s the key t o s u c c e s s f u l c a t c h e s .  Hiqh  hauls  o f t h e path  of a large catch  as copepods a r e r i c h ruptured  of  reduces  i m p r o v e t h e c a t c h r a t e may be o v e r l o o k e d .  More s e r i o u s l y ,  landed;  results  p e r i o d s , adjustments  towing  prolonqed  c l o g g i n g o f meshes which  aqainst the t i d a l  by f i s h e r m e n  who a l s o  t o the  s e t near the  currents.  Such  p a r t i c i p a t e i n the  143 gape n e t f i s h e r y  f o r salmon. One man i n a s m a l l b o a t  v e s s e l s a r e used) c a n t e n d up t o 10-15 a n c h o r e d During are In  the height o f the plankton  emptied  net t h e codend i s h a u l e d by  hand  unless  are l e f t  packaged The  without 400  The c a t c h in  days  good  Bergen t o Trondheim also  made  in  usually  June.  Unfavourable  plankton  into  the  surface  of cladocerans  from  netof  used  i f  i t is plant.  deal.  A  periods up  to  the coast  the  trials  from were  Norway. The c o p e p o d  and  extends  to  late  by n o r t h e r l y winds  offshore,  and l a r v a e o f  carrying  the  c o a s t . A l s o t h e heavy benthic  invertebrates  may sometimes r e d u c e  the guality of  in  fjords  ctenophores  such  as  Bolinopsis  from  is  successful  of northern  waters  away  nettable plankton  abundant; t h e y  a lift  freezing  along  c o n d i t i o n s c a n be c a u s e d  drive  aboard  recorded.  although  catch  excluded  lifted  varies a great  primarily  the Calanus  become v e r y  t o a shore  a t t h e end o f A p r i l  concentrations  recruitment  is  (60-64N)  begins  to  and  i s abundant, c a t c h e s o f  the Lofoten area  season  which tend  line  a r e o f t e n f o l l o w e d by l o n g  kg p e r n e t p e r n i g h t have been  fishery  nets  i n the evenings.  and a w i n c h  t h e swing nets  any c a t c h . When p l a n k t o n  Calanus  swing  i n t o a d r a i n i n g box b e f o r e  bags and t a k e n  catches  nets.  o p e n . To empty t h e s t a t i o n a r y  t h e codend  i s emptied  plastic  of  The  the  the c a t c h i s l a r g e . I n t h a t case  s i z e o f c a t c h e s from  few  season,  by t h e h e a v i n g  h e a v i e r mesh i s p u l l e d o v e r necessary.  swing  i n t h e morning and sometimes a l s o  s l a c k periods the nets  (7.6-10.7 m  and  may  t h e c a t c h o f swing  island  areas.  infundibulum  clog  towed  may  nets  n e t s by a b a r r i e r  Medusae  and  occasionally but  can  be  net placed a t  144 the  mouth.  the  fjord  At t h e same t i m e a few water  but  may  consist  zooplankton  still  in  kilometres offshore, the  coastal  almost e n t i r e l y  outside  current,  the  of Calanus f i n m a r c h i c u s  (Wiborg, 1976) .  During O  Calanus  I  nets.  An  1975  with  was  about  the  aim  yield  increased,  w i t h towed n e t s about  the  Calanus  pending the d e t a i l e d  main  astaxanthin  /kg  m e t r i c t o n s , mostly  from  was  tons.  fishery  study  It might  of  catch  stationary  planned  80 m e t r i c t o n s . The  10-100 m i l l i o n  of  concentrations of  desired  t h e a n n u a l Norwegian  of z o o p l a n k t o n a l o n g t h e N o r w e g i a n c o a s t  the  The  1975,  of landing  be o f t h e o r d e r o f  that  50  experimental f i s h e r y  production to  r e c e n t y e a r s up t o  for  annual  i s estimated  is  anticipated  be  considerably  swarming  and  other  plankton(Wiborg,1976).  use o f C a l a n u s  i n Norway h a s  i n salmonid r e a r i n g  red c o l o u r .  (0tne,1974)  Raw  and  to  give  been a s a s o u r c e o f  the  fish  C a l a n u s c o n t a i n s up t o 85 as much as  918  of Calanus  (about  flesh  the  mg a s t a x a n t h i n  mg/kg o f o i l ( F i s h e r  et a l  x  ,1952). The is  present price  too  high  aguaculture, for  later  copepods similar  for  i t  to  be  a l t h o u g h some f i s h  use.  to those f o r k r i l l  Because  a s a major  dietary  farmers catch Calanus  2-3/kg) item i n  themselves  E x p e r i m e n t s a r e underway t o d e v e l o p p r o d u c t s f r o m  f o r human c o n s u m p t i o n .  zooplankters  used  Norwegian k r .  i s very  of  The  problems  encountered  are  as t h e p r o x i m a t e c o m p o s i t i o n o f t h e s e  similar.  the pattern o f d i s t r i b u t i o n  and t h e  relatively  145 short  fishing  presently  season,  no  foreseen,  overfishing  even  at  of t h e copepod  considerably  plankton  is  levels  of  higher  exploitation. In  some Norwegian  during  February  fjords,  to A p r i l  by  Meganyetiphanes n o r y e g i c a Thysanpessa  inermis  years the annual mainly  for  personal  5.233  In  3000  commercially  l u r e s and  principal  been a b o u t  dip  species 196 6 and kg  nets.  although subseguent  which  of rainbow trout(Wiborg,1966;  Columbia s  plankton  ,  is  J.  used  Matthews,  fishery,  E  paeifica  A  and  plumchrus .  Interest Canada  was  i n plankton first  Biological  estuary.  fishermen. Public  plumchrus  out The  scientists  at  in  , i n the v i c i n i t y  conjunction  and  was was  sold also  coast  the  of t h e  with  as a f i s h tried  and  at  the  Fraser Biver E  several food  of  Nanaimo  described catches of  h a r v e s t i n g o f t h i s copepod  catch  Aquarium  by  P a r s o n s (1972) has  Experimental  carried  h a r v e s t i n g along the P a c i f i c  stimulated  Station.  copepod, Calanus  was  the  contributes.  c a t c h has  fished  communication).  British  Calanus  are  means o f l i g h t  is  also  culture  krill  paeifica  A  commercial  to the  Vancouver  government  fish  hatcheries(Parsons,1972).  For only  a few  catch  less  was  the  years  fishermen  was  fishery boat,  several  not  first  after  the i n i t i a l  were i n v o l v e d i n the  than  10  developed  tons any  of  experiments  fishery;  E^ p a e i f i c a  further).  Operating  Canadian commercial plankton  .  in  1970  the  annual  (The  copepod  from  fishermen  a used  small a  10  146 m  long  sguare  equipped  f o r the  mesh o f t h e  codend  of  a  of p l a s t i c  in  baqs.  plastic  December  modified  1974  with  surface floats  its  zippered qear  area  by  easier  codend. F u r t h e r  f o r commercial combininq  two  use  26  vane and bonqo  m.  v i a the  nets  cleared  the  draininq  over  riqqinq  possibly  The  when t h e waters present  depth  a 54-ton  the  bridle with  to a sinqle a 12  the  m x 3.7 a  resulting  nets of  the  strain  towinq  Strait  is  not  The a  of Georgia  The  that  they in  handlinq  time  aspect of  in  a  catches  in  r e g i o n , but or  of  warp.  handicap  h a n d l i n g problems i n rough seas  alonq  depressor  when  hiqh  scale  area  dumped  net  net  throuqh  nets  larqe  the nets  i n each net.  were h a u l e d  m)  m s t e e l boom so  arranqement kept  d i d tend to  were l i f t e d  the  filterinq  mouth  were a t t a c h e d t o a s i n q l e  raised  than  proved  catch  enlarqinq  a  fishinq  IKMT d e s i q n  "bonqo" IKMT had  was  with  modifications introduced to  (3.7  net  and  made  of f i s h i n q  f o r emptyinq  The  a  f r o z e n onboard  d e c k , a l l o w i n q t h e c a t c h t o be  s h o r t , but kq  lenqth  aboard  the  screwed onto  were  f r e e z e r . The  square-mouthed  wire-rope  boat's  200  sheltered  nets  c o u l d be  box.  reasonably of  The  2  in  hauls  included  a common s i d e ; t h e r e s u l t i n q about  m  trawl  for selectinq  while  the cone of the net. 100  as  fishery.  k n o t l e s s nylon which  was  b a r s much  copepod  d r a i n i n q , t h e c a t c h was  midwater  and  horizontal  bucket  p i p e on  w i n c h e s and  more v e r s a t i l e  with  the  6 mm  experimental  Isaacs-Kidd  v e s s e l equipped  and  mouth) which  Norweqian  on a p o l y e s t e r warp a b o u t by hand. A f t e r  be  was  plastic  retrieved  to  m x 2 m i n the  bridle  e u p h a u s i i d net  section  towed  In  2  towed n e t s i n t h e  consisted  threaded was  (about  with s u r f a c e f l o a t s ,  described The  net  a  the the  would hiqh  147 wind. The  vessel  harvesting Channel  i n Saanich and  1976  the  tons.  During  rn i n  tons  total  1976, f i v e  in  vessels  with  1976 were Howe Sound Sechelt  Inlet  The  nets landed days  season  operations  to  i n 45 d a y s f i s h i n g . in  the  recorded  E  euphausiid  by a r e a  Eacifica  f o r Malaspina  catch  region  x  in  p e r i o d was a b o u t 45 the  euphausiid  IKMT t r a w l s g e n e r a l l y a b o u t 13 from  Saanich  Inlet  in  o f 51.7 t o n s .  E. p a c i f i c a  was h a r v e s t e d  Inlet  (4,4  during  tons),  and  from  January  effort.  to  The boat  the C r o f t o n area  April  with  1977 saw  bongo  IKMT  where 68 t o n s  c a t c h i n g 8,8 t o n s .  Inlet  in  were  for 9  Total catch  boats  Additional  landed  from  r o s e t o 17.4 t o n s  a l l areas  1977 were a b o u t  in  the  104 t o n s .  i n T a b l e 21.  about  small catches  (1 ton) and Howe Sound  Sechelt Inlet  i s summarised  two o t h e r  1977,  Strait  l a n d i n g s from  i n early  from  was t h e r e f o r e a b o u t 76.8 t o n s i n e a r l y 1977,  Meanwhile i n S a a n i c h of  Inlet;  Another v e s s e l a l s o harvested  Crofton area,  Crofton area  tons  i n Saanich  1975  (10.6 t o n s ) .  patterns of fishing  moved  area (Stuart  January-March  joined  (2.5 t o n s ) , J e r v i s  harvesting  shifting  where  in,euphausiid  Crofton  During  for a total  localities  the  f o r a comparable  a l l were e g u i p p e d  Other  been u s e d  were c a u g h t  other  1976 was a b o u t 6.7 t o n s  The  and  mouth a r e a . The a d d i t i o n a l c a t c h  2  the  has  Narrows).  40 m e t r i c  vessel's  above  Inlet  Sansum  appproximately  fishery;  described  (0,2  9  were ton).  i n 1977. T o t a l  Strait  of  Georgia  The breakdown o f c a t c h  148 TABLE 21, Summary of euphausiid c a t c h e s by s t a t i s t i c a l ( F i s h e r i e s and M a r i n e S e r v i c e ) and l o c a l i t y f o r 1975-77. Year  Statistical areas  Locality  1975  18  1976  18 16 16 28 All  Saanich I n l e t Sechelt Inlet Jervis Inlet Howe Sound Total  1977  17 18 16 16 28 All  Crofton Saanich I n l e t Sechelt I n l e t Malaspina S t r a i t Howe Sound Total  The night  when  freguency to t e l l  Saanich  B r i t i s h Columbia  or sonar.  catches.  sampler  concentrations.  harvesting  success  The  boats*  close  be  effect  detected  by  the corresponding  will  yield  a small high useful  of  per  speed  t o judge  experience  unit  a c t i v i t y over  on  number o f d a y s f i s h e d  the fishery.  Values  are based  c a t c h e s from  a vessel  a bridge l o g o f daily  shows  effort  (CPE)  the f i r s t  season  With t h e e x c e p t i o n o f t h e  date o f e n t r y i n t o  trawl;  high-  i t i s possible  curve  p o i n t on t h e c u r v e s r e p r e s e n t s t h e a v e r a g e  on d a i l y  out a t  to the s u r f a c e .  echosounder  catch  continuing plankton f i s h i n g  two i n t h e f i s h e r y .  otter  i s carried  i s c l e a r l y e v i d e n t i n F i g u r e 35 w h i c h  the p a t t e r n o f i n d i v i d u a l  trip;  76.8 9.0 17.4 1.0 0.2 104. 4  as the M i l l e r net are a l s o  commercial  each  51.7 10.6 4.4 2.5 69.2  T e s t samples taken with  such  tons  40.0  With p r a c t i c e ,  whether a g i v e n showing on t h e  plankton  left,  migrated  of these zooplankters can  echosounders  reasonable  or  Inlet  euphausiid fishery  t h e e u p h a u s i i d s have  Heavy p a t c h e s  with  Catch JJL  area  on  CPE f o r a  i s cumulative  o f CPE i n t h e f i r s t using a  c a t c h had been  3.7  the  x  from curve  3.7  m  m a i n t a i n e d by  149  0  10  20  30  40  50  60  70  DAYS FISHED  FIGUBE 35. The e f f e c t of fishing experience on e u p h a u s i i d fishing success, CPE i n S t r a i t o f G e o r g i a w a t e r s d u r i n g t h e 1976 and 1977 s e a s o n s .  t h e crew  who were on t h e i r  The  first  plankton  g e n e r a l t r e n d i n CPE i n c l u d e s a s h a r p r i s e  first  one  season  a p l a t e a u i n CPE d e v e l o p e d  reached CPE  for  or  a second  is  could  trip.  quite  two  trips.  and h i g h e r dependent  During  subseguent f o r two  during  t r i p s i n t h e same  vessels.  p l a t e a u d u r i n g i t s second on  fishing  the  One  boat  season,  experience these  as  patterns  be d e s c r i b e d a s " l e a r n i n g " c u r v e s . A l s o , t h e t h r e s h o l d CPE  a new f i s h e r m a n  t o stay i n the f i s h e r y  100  kg/day. One f i s h e r m a n q u i t  than  this  w h i l e a second  quit  appears  when h i s f i r s t  trip  to  be  yielded  about less  after a particularly disappointinq  150 trip  even though  b e t t e r f o r over  on t h e a  average  based  n e t s and  so on; h i s l o w e s t  present  market  price  to  dry  e s t i m a t e was  1800  weight  dry t o n  form  f o r producing  fishermen  i s available  completed  t o be  after  from  in  the  and  processing  the  catch  of  tends  as  spoil.)  The  a  previously lubricating another  1976  of  pound s t e r l i n g .  The  circulated  season.  catch. the  who  vessels  eguipped (It  limiting must  with  hydraulic so equipped. oil  and  major i t e m . By  winch  or  plastic prorating  this  replied  be  drum  be  noted  the  two  sample  size  presently  up  the  initial  as  for  on-board  that  freezing daily  frozen lest f o r the  they  fishery  or more), vessel  include  used;  used  maximum  (100 k h z i f  i f  several  are p r i m a r i l y  expenses  bags  ton  Only  vessels  promptly  sounder  a  are considered  f a c t o r f o r the  Operating  cn  {The g u e s t i o n a i r e  freezers  should  to  reguest.)  major e g u i p m e n t e x p e n s e s t o g e a r a high-freguency  based  What i s t h e c o s t t o  multi-purpose  Both  Columbia  estimate the costs of  upon  fisherman  the  g dry  the e g u i v a l e n t of a dry  author  euphausiids  are f o r the net, possibly  are  t o be  the  of  fishery.  salmon t r o l l e r s  capacity  the  o f the  representative  engaged  the  of  efficiency  g u e s t i o n a i r e s were r e c e i v e d . A l t h o u g h  s m a l l , the boats  (0.1  {2000 l b . ) ,  conversion factor.  h a r v e s t i n g a g u e s t i o n a i r e was  euphausiid  plankton  filtering  11,800 l b . ) o f f r o z e n e u p h a u s i i d s ? To  euphausiid  is  season,  $3530 p e r  the plankton fisherman {ie.  marginally  for frozen euphausiids i n B r i t i s h  e q u i v a l e n t t o about wet  only  the c o s t o f h a r v e s t i n g a dry ten  per  3  0.17  managed  on assumed c o n c e n t r a t i o n s o f  wt/m ), h a r v e s t i n g h o u r s  is  had  season.  Jackson(1954) e s t i m a t e d plankton  he  was  fuel  not and  crew s h a r e s eguipment  and  are  costs  151 over  the  first  year,  the  following  costs  p e r d r y t o n were  estimated:  One v e s s e l f i s h e d tons.  "dry"  19 days p l u s 3 d a y s t r a v e l l i n g ;  Operating expenses(fuel/oil,etc)at Crew s h a r e s Equipment c o s t s ( $ 3 2 0 0 , p r o r a t e d ) Total  $32.50/day  c a t c h 1.6  $610, 596. 2000. $3206.  T h e r e f o r e t h i s b o a t made a p r o f i t o f a b o u t $324 per " d r y " ton a f t e r p a y i n q o f f t h e n e t , w i n c h , warp and e c h o s o u n d e r w i t h i n the first year. Of c o u r s e t h i s e q u i p m e n t i n s u b s e q u e n t years c o u l d be used t o h a r v e s t e u p h a u s i i d s a t a p r o f i t l e v e l o f about $230 0 p e r d r y t o n , n o t i n c l u d i n g d e p r e c i a t i o n c o s t s .  catch  The other 4,6 " d r y "  vessel tons.  fished  5 9 days p l u s 10 d a y s  Operating expenses(fuel/oil,etc)at$19.00/day Crew s h a r e s ( 2 5 % g r o s s ) Equipment c o s t s { $ 7 0 5 , p r o r a t e d ) Total  travelling;  $285. 887, 153. $1325.  T h i s v e s s e l made a f i r s t y e a r p r o f i t o f about $2205 p e r "dry" t o n ($412 p e r wet m e t r i c t o n ) ; equipment c o s t s were l o w e r as t h e f i s h e r m a n made h i s own n e t and t h e b o a t was already e q u i p p e d w i t h a winch and s o n a r .  Takinq its the  level  into  i n the e a r l y  interveninq  analysis  waters. can  be  such  d e v a l u a t i o n o f t h e pound s t e r l i n q  1950's, and t h e i n f l a t i o n  years,  seriously  zooplankton likely  account  i t i s  apparent  overestimates as e u p h a u s i i d s  the  that cost  in British  t h e c o s t o f h a r v e s t i n q c o p e p o d s and Euphausiid quite  especially  profitable  f o r multi-purpose  and b e f o r e t h e s p r i n q  harvestinq,  then,  can  of  krill  prices  Jackson's  Columbia  i n the S t r a i t  because t h e h a r v e s t i n q season  salmon f i s h e r y Zooplankton  harvestinq  of  in  from in cost  harvestinq w a t e r s and Norweqian  o f Georqia reqion fishinq  vessels,  comes a f t e r t h e summer  Pacific  herrinq  act  a  as  useful  fishery. form o f  152 employment f o r generally growinq various  a  slow  limited  time  of the year.  manufacturing products  Despite Columbia Recently,  the  fishermen  In a d d i t i o n ,  and  promising and  domestic  beginnings  industry,  the  B,ft. C r o u t e r , D i r e c t o r o f  Directorate  of  guidelines  "to  the  Fisheries  durinq  meet  the  threat  of  t h e r e i s a new  e u p h a u s i i d s , the statement  plankton  this  future the  and into  new is  Field  British  uncertain. Operations,  has i s s u e d management of  briefly  their  markets.  Service,  resource"(Anonymous,1977b). A f t e r harvesting  of  industry f o r processing the  f o r export  fishery Mr.  number  overfishing  describing  continues as  the  methods f o r  follows:  "Zooplankton f o r m t h e b a s i c f o o d r e s o u r c e s f o r many m a r i n e f i s h e s , and a p l a n k t o n f i s h e r y could reduce their food supply unless carefully controlled. Accordingly, the g u i d e l i n e s f o r this fishery take i n t o c o n s i d e r a t i o n t h i s important c o n s t r a i n t . Current scientific knowledge i n d i c a t e s t h a t a f i s h e r y i n o f f s h o r e w a t e r s c o u l d have l i t t l e effect due to the vast plankton resource available. However, in the Strait of Georgia, zooplankton abundance i s s m a l l e r and a l a r g e f i s h e r y w i l l n o t be permitted. The g u i d e l i n e s and management c o n t r o l f o r t h e z o o p l a n k t o n f i s h e r y a r e as f o l l o w s . To enable this developing i n d u s t r y t o d e s i g n f i s h i n g e g u i p m e n t and p r o c e s s i n g technology i n p r o t e c t e d waters, a f i s h e r y of n o t more t h a n 500 t o n s a n n u a l l y w i l l be allowed in t h e S t r a i t o f G e o r g i a u n t i l 1980. T h i s amount i s l e s s t h a n o n e - t e n t h o f one per c e n t of the annual food requirements of a l l f i s h e s i n the S t r a i t of Georqia, accordinq to s c i e n t i s t s . The f i s h e r y i n G e o r q i a Strait (sic) i s also limited t o t h e w i n t e r months o n l y ( J a n u a r y t o March a n n u a l l y ) , to minimize the p o s s i b i l i t y of catchinq larval fish or shellfish which are found i n the summer months. Z o o p l a n k t o n a r e a l s o n e a r t h e end of t h e i r l i f e c y l c e i n t h e w i n t e r months when t h e y w i l l be a l l o w e d t o be f i s h e d . After 1980, there will be a m o r a t o r i u m on plankton f i s h i n q i n the Gulf of Georqia ( s i c ) . I t i s  153 a n t i c i p a t e d t h a t t h e i n d u s t r y w i l l have d e v e l o p e d t o t h e s t a g e where t h e y w i l l be a b l e to f i s h i n the outside waters by that time. Further policy development f o r t h e a n t i c i p a t e d f i s h e r y o u t s i d e the S t r a i t o f G e o r g i a w i l l be d e v e l o p e d i n t h e f u t u r e a s i n f o r m a t i o n from o n - g o i n g s t u d i e s becomes a v a i l a b l e . "  In  C h a p t e r 6, t h e announced  harvesting  i n the  conclusions model the  obtained  t o cohorts  guidelines  some  of  fishery  for  from  also  which  winter.  In  offshore  plankton  One o n l y  has t o look  fishery  for Pacific  for  these  the  ''outside"  would have t o purpose  required  fishery  point,  however,  but c l o s e l y  monitored  of  Georgia  involves  would b e i d l e  industry  sheltered areas). compete  /or  for  f o r new  record  much  to r e l y  of  For  multiof  the  under  i n that  specially  area  euphausiid  on s t o c k s  harsh  spring  i n the  designed  sea  An o f f s h o r e  euphausiid  convential heavy  processing  construction  in  f i s h e r y i n summer  fisheries capital  industry  and  conditions  w a t e r s were a v a i l a b l e f o r h a r v e s t i n g  vessel  the  of Vancouver  the  entirely  require  operate  with  be  sea c o n d i t i o n s .  of operating  winter.  Conseguently, the  will  several  o f f t h e west c o a s t  in  to  behind  b o a t s would n o t be s u i t a b l e f o r a n  would l i k e l y  vessels.  f i s h e r m e n and  reasoning  At t h i s  Strait  the d i f f i c u l t i e s  vessels  {unless other  the  herring  harvesting/processing  constructed  . The a p p a r e n t  to t h e p o o r s a f e t y  periods  waters  yield  f i s h e r y i n w i n t e r due t o rough  t o appreciate  "outside"  a p p l i c a t i o n o f the Beverton-Holt  otherwise  general,  extended  with  the  be  plankton  compared  in  present,  to control  will  o f a continuing  euphausiids At  Georgia  be d i s c u s s e d .  advantages  purpose v e s s e l s  Island  of  o f E. p a c i f i c a  will  the  mentioned.  Strait  guidelines  for  multi-  investment  would  when t h e r e  likely  by be  are already  15U suitable That  vessels for a  is  feasible,  not  t o say  but  t h a t the  limited t h a t an  of  i s that  quite  well-defined  mortalities. (eg.  The  Walters  information well.  i t offers  The  and  yet  populations  to  Hilborn,  the  to monitor  could  of  in  this situation.  s c r u t i n y , t h o u g h , as Strait  of  a crash  Georgia  production  area  euphausiid could  i n the southern  be  B.C.  the  water  species  Such a p r o g r a m in  the  provide  c a r r y i n g c a p a c i t y of such zooplankton  assessed  i s not  euphausiid  h a r v e s t i n g and  "outside"  of commercial f i s h  fishery  inshore  control  1976)  fishery.  t o be e s t a b l i s h e d .  continuing  opportunity  f o r management o f  populations  herring  a  has  approach of adaptive  increased  the  to an  euphausiid  offshore euphausiid  feasibility  A f u r t h e r advantage fishery  "inshore"  response natural fishery valuable  stocks  as  populations  for  might  also  be  would r e g u i r e c l o s e populations  within  d i s a s t r o u s t o salmon waters.  and  155 CHAPTER 6:  6.1  NET  S E L E C T I V I T Y , YIELD AND  MANAGEMENT CONSIDERATIONS  Introduction  All  members  generally  not  of  a  equally  sampled  or  harvested  susceptible  to capture  due  to physical  or  b e h a v i o u r a l d i f f e r e n c e s w i t h i n the  information is  properties of the  on  the s e l e c t i v i t y  important  Net  no  behavioural  and  throuqh  1975), t h e  relative  assessed  by  was  comparing  Conversions  t o weight  described  selection  selectivity  as  Consequently, in  use  and  body  of the  compositions here  length  was  the  and  are  possible  age  Pope  different  Selectivity  the  to  effects  p r o c e s s e s or to  designs(eg.  the  qear  et  raeaure aJL. , ,  types  of catches  refers  measure  of  with  to  used taken  length  size  used.  relationships  earlier.  Chapter  2,  r e f e r e n c e was  c o m p a r i n g c a t c h c u r v e s f o r MNT that,  although  n e t s , t h e numbers o f l a r g e r represented hauled  population.  made h e r e t o s e p a r a t e  experimental  selection  appeared  morpholoqical  o f t h e v a r i o u s equipment  mechanical  under s i m i l a r c o n d i t i o n s .  In  tc  qear,  fishery.  attempt  selectivity  was  a qiven  are  Selectivity  Although of  and/or  by  t o the e s t i m a t i o n of p o p u l a t i o n parameters  t h e manaqement o f a  6.2  qear  population  net  and  similar E  ti  the  SCOR mesh  pacifica  i n t h e SCOR s a m p l e s . by  made t o n e t  more m o b i l e  nets  selectivity (Figure  sizes  were used  ( o v e r 19  Avoidance  17}.  of  e u p h a u s i i d s was  mm) the  were  when It  i n the under-  vertically  suggested  as a  156 possible On  cause. Saanich I n l e t  sampling shaped month be  with length  n e t s and SCOR n e t s  freguency  under-represented samples  Strait  from  alternative curves  of  Saanich  f o r the  f o r the nets  may  euphausiids i n Saanich I n l e t due  to mortality  Percentage  august  or other  Figures  in  distributions. 22  mm;  a  second  mm  Jervis  and  be t h e l o w e r  availability  Thus  average  and  a  catch  of larger  and w i n t e r  by  size  class  months,  f o r MNT, SCOR and  a t Saanich I n l e t Figure  36.  at  the  tails  SAa-2  station  There  o f t h e maximum a t 14-15  at  i s  mm, of  general  but the  18-22  mm  was a l s o  s i n g l e specimen  that  a t 17-19 a  second  more  length 9  to  p r e s e n t . The MNT  i n d i v u d u a l s , b u t showed o n l y a  Only a shoulder  indicated  an  causes.  mode mm  19  I n l e t and  13).  the  shoulder  a t 21 mm a s e v i d e n c e  mode. I n c o n t r a s t , t h e IKMT d i s t r i b u t i o n  t o 21 mm. 21  mm  to  (over  T h e SCOR n e t s a m p l e i n c l u d e d s p e c i m e n s from  second  18-19  appear  in  representation  sample i n c l u d e d 8-21 at  11  during the f a l l  compositions  i n the p o s i t i o n  variation  n e t s i n each  differences  21, 1975 a r e shown i n  agreement  similarly  large euphausiids  w i t h s a m p l e s from  IKMT e u p h a u s i i d s a m p l e s c o l l e c t e d on  f o r both  e u p h a u s i i d s d i d not  Inlet,  Georgia (cf.  reason  in  i n t h e SCOR c a t c h e s . However, i n O c t o b e r -  were s c a r c e i n c o m p a r i s o n  the  1975, e x t e n s i v e  resulted  distributions  ( F i g u r e 9A, B) . The l a r g e r  February mm)  Miller  c r u i s e s i n J u l y and a u g u s t  ranged  mm and a s i n g l e  from  of a 12  individual at  mode might be p r e s e n t  i n the  population.  Selectivity  o f t h e IKMT i s more n o t i c e a b l e a t s m a l l e r modal  157  2  SAA A U G U S T 1975  BODY L E N G T H  FIGURE  36. C o m p a r i s o n o f s i z e composition of euphausiid catch f r o m SCOR ( • ) , MNT (v) and IKMT (•) h a u l s i n S a a n i c h I n l e t , a u g u s t 1975.  a comparison o f t h e s i z e  sizes,  SCOR and IKMT s a m p l e s from SCOR  distribution  13  and a low s h o u l d e r  mm  mm  a high degree o f individuals  of  composition  March  of euphausiids  1975 i s g i v e n i n F i g u r e 37. The  shows a s m a l l mode a t 8 mm,  13  mm  a larger  mode a t  a t 16-19mm. The IKMT d i s t r i b u t i o n  selectivity  from  f o r the  14-15  body l e n g t h and l e s s  mm  shows  euphausiids;  are greatly  under-  represented. A final  example  i n F i g u r e 38 compares t h e c a t c h  of c o n s e c u t i v e tows by similar ca.  mesh s i z e  5 mm).  mm  and  a s t h e codend  The MHT d i s t r i b u t i o n  the d i s t r i b u t i o n Again,  MNT  selection  i s apparent.  by  a  commercial  o f t h e IKMT used indicates  trawl  in this  t y p e o f t r a w l a t body  with  study  a mode a t 12 mm  f o r t h e c o m m e r c i a l n e t h a s a maximum by t h i s  composition  at  {  while 14mm.  lengths over  13  158  SAA 4.7 MARCH 1975  40  30  u O V  V /••  20  \  10  m \  .c.  10  II  12 13 14 15 BODY LENGTH mm  Vi  17  18  19  20  FIGURE 37, C o m p a r i s o n o f s i z e c o m p o s i t i o n of euphausiid from SCOR («) and IKMT (•) h a u l s i n S a a n i c h I n l e t , March 1975.  In size  summary,  distributions  locality.  In  euphausiids spring  for  of  E  t  depend  yield on  harvesting, cohorts  the  several  (eg. growth  over  by l a t e  and  during the harvestable  samples  about  from  this  13-14  the  mm.  corresponds  September  same select  For  t o an age o f  including fishing characteristics  lifespan).  10,12  Fishery  of t h e euphausiid  natural  the  to e a r l y October.  of t h e Euphausiid  i n weight  rate,  guite consistent  o f a b o u t 5 months ( c f . F i g u r e s  factors,  mesh s i z e ,  give  IKMT and c o m m e r c i a l t r a w l s  paeifica  Yield  or catch  nets  contemporary  to the fishery  14) which i s r e a c h e d  The  and MNT  body l e n g t h s  6.3 F a c t o r s A f f e c t i n g  size  SCOR  contrast,  with  cohorts  recruitment and  the  catch  of  fishery  effort, the  will  time o f  harvested  m o r t a l i t y r a t e and maximum I t has  been  shown  that  159  FIGURE 38. C o m p a r i s o n o f s i z e c o m p o s i t i o n of euphausiid catch from Miller net (MNT) and c o m m e r c i a l p l a n k t o n n e t tows t a k e n c o n s e c u t i v e l y i n S a a n i c h Inlet, January 1977.  growth von  i n each  Bertalanffy  exponents mortality until  are  year  growth c u r v e s and nearly  is fairly  late  f o r E^ p a c i f i c a  3.0  o f t h e model o f B e v e r t o n The  following  analysis  from  Saanich I n l e t  and  Holt(1957)  C l a r k e t §JL The  A  f o r both sexes. In a d d i t i o n ,  natural  by  and  and  mm).  the  early  maturity  Conseguently  Holt(1957)  appear  examines t h e y i e l d  of E  u s i n g the e g u i l i b r i u m by  length  by  weight  ( o v e r 18  that  be d e s c r i b e d :  c o n s t a n t from  adulthood  c o h o r t s can  i3L  (ca.  12  mm)  the  assumptions  t o be  satisfied.  pacifica  approach  of  cohorts Beverton  u s i n g t h e o p t i m a l dynamics approach  of  (1973).  parameters  o f t h e B e v e r t o n - H o l t model  for  first-  and  160 second-year Table  22.  paeifica  Values  values obtained Bertalanffy  of  i n Chapter  eguation  w(t)  asymptotic  is  of  = l  the  recruitment  r  into  the  from t h e  end  of  they  were d i f f e r e n t  [  t  in  weight are  0  was  at  time  t,  and  the  same  as  for  from t h e  taken  The  stocks,  two  due  between t h e  r  E  each c o h o r t  of  to  first  v a r y i n g the  m o r t a l i t y , F,  on  a r e shown i n t h e  For both  von  cohorts,  i s  the and  larqe  22,  von  the of  age  aqe full  Age at  as i f in  seasons.  parameters f o r f i r s t in Saanich Inlet  Sprinq  of the  difference  second qrowinq  and  75  26.2 0.35 -0.5 5. 11. 0.35 0.70  age  at f i r s t  the e q u i l i b r i u m yield  the  the  c o h o r t s were examined  73.4 0.45 9.2 16. 22. 0.50 0.80  a  fishing  Lao  the  ?  body l e n q t h  as t h e c o h o r t  S p r i n q 74  ¥ ^ (mq) K t (mo) t (mo) T (mo) n (min) H (max)  effects  weight  ]  22. Beverton-Holt y i e l d model s e c o n d - y e a r E^ p a e i f i c a cohorts durinq 1975.  The  of  0  April.  Parameter  the  terms  m i d - w a t e r t r a w l f i s h e r y ( 1 3 - 1 4 mm). E  growth parameters  given i n  from t h e c o r r e s p o n d i n g  1 - exp{-K(t-t ))  estimated  fishery, T ,  fishing  In  are  f o r growth i n l e n q t h . I n T a b l e  t , was  exit  TABLE  a  body  equation  recruitment,  2.  i n 1975  is :  w e i g h t . K and  Bertalanffy  observed  were c a l c u l a t e d  w(t)  where  cohorts  contours  yield/recruit  rises  capture,  t , c  yield/recruit  of Fiqure  much  39  faster  and  for  and for 40.  a  161  FIGOBE  39. C o n t o u r s o f e g u i l i b r i u m y i e l d / r e c r u i t f o r t h e s p r i n g 75 c o h o r t o f E._ p a c i f i c a i n a f i s h e r y commencing at time t= 11 mo. ( A p r i l ) . I n p a r t A, M - 0.35 w h i l e i n p a r t B, M = 0.70; K =0.35 t h r o u g h o u t .  162  FIGOEE 40. C o n t o u r s o f 74 c o h o r t o f JU t i m e t=22 mo. I n = 0.80; K = 0.4 5  given  increase  in  spring eguilibrium y i e l d / r e c r u i t f o r the p a c i f i c a i n a f i s h e r y commencing a t p a r t A, M = 0.50 w h i l e i n p a r t B, I! throughout.  fishing  mortality i f harvesting  b e g i n s when  163 the  cohorts  are f i r s t  the  h a r v e s t i n g season  yield/recruit  the  month  the  harvesting similar the  between J a n u a r y and increases i n  percentage  higher.  Thus  increases the  are l i k e l y  equilibrium yield  in  at  yield/recruit  advantage  of  t o be s u b s t a n t i a l ,  January-March  three  months,  f o r a given  commencing  according to  fishing  there  i s  also  much  hiqher  m o r t a l i t y i f t h e season as  e  runs  opposed  to  ( t =8;t = 11). c  optimal  optimize  g  d y n a m i c s a p p r o a c h o f C l a r k e t a l - (1973)  levels  body  size  of  the  harvested  o f t i m e - d i s c o u n t i n g , "\ . If discount  of optimal  rate)  f o r the euphausiid  time  for  t h e c o h o r t ( C l a r k e t a l . , 1973). The o p t i m a l  according t o their  harvest  one  the  effort,  seeks  A  the  (ie. zero  fishing  are  approach.  c  ^=0  natural  yield/recruit  from O c t o b e r t o t h e end o f D e c e m b e r ( t = 5; t = 8)  different  month  41 shows t h a t i f t h e l e n g t h o f t h e h a r v e s t i n q s e a s o n  maintained  to  season  i n c r e a s e s by 88 t o 60% f o r e a c h  and September. A t h i g h e r r a t e s o f  i n body s i z e  The  the  e a r l i e r when t h e c o h o r t s a r e n u m e r i c a l l y s t r o n g e r b u t  Figure is  March,  (at a n a t u r a l m o r t a l i t y o f  the corresponding  F=0.20)  added between J a n u a r y  significantly  that  33 t o 17%. F o r t h e s p r i n g 74 c o h o r t , t h e y i e l d / R  and  mortality,  a t t h e end o f  t h a t t h e season s t a r t s  September;  length a r e only M=0.50  finishes  Given  m o r t a l i t y o f 0.20) i n c r e a s e s by 50 t o 30% f o r  earlier  preceeding  (at  always  t o the t r a w l f i s h e r y .  of t h e s p r i n g 75 c o h o r t  0.35 and a f i s h i n g each  available  Fisher  i s at t h e t i m e  Rule  i s to apply  of  animals  under  assumes  that  fishery,  then  maximum  biomass  harvest  strategy  t h e maximum  possible  Fmax, f o r a s h o r t p e r i o d a t t h e t i m e  o f maximum  164 12  .1  .2  .4  .3  .5  .6  .7  F FIGDBE  41. Relationships between yield/recruit and fishing m o r t a l i t y f o r 3-month f i s h e r i e s b e g i n n i n g i n O c t o b e r and J a n u a r y , r e s p e c t i v e l y .  biomass i n o r d e r  to q u i c k l y reduce the  where  biomass,  B  effort  and  Ideally  one  sufficient  c/p  (here  p i s the p r i c e per miqht e x p e c t  that  to  a new  qenerate  or l a r g e r than  From t h e harvest  =  t h a t of the  population  c i s the  weight o f  this  remaining  parent  a  cost of a unit  unit  cohort  to  harvest  fishing  product).  population  of similar  would  maximum  Beverton-Holt  t^ = t  D  + 1/K  [  model i s g i v e n ln(1  be  biomass  generation.  a n a l y s i s o f C l a r k e t a l . . (1973) t h e o p t i m a l  f o r the  level  + 3K/(M  by:  +*))  ]  age  of  165  HhenA=0, For  the optimal  t h e s p r i n g 75 c o h o r t  This  corresponds  to  age i s t h e age  of E  about time  cohort  13  recruitment  into  conclusions approach  be  about  are i n  the mm,  t h e mid-water  from  maximum  biomass.  , t^=3.5 mo when M=0.35.  e a r l y September f o r a c o h o r t  began i n mid-Hay; a t t h i s would  pacifica  A  of  mean  body  length  fishery.  agreement  regarding  of f u l l  Therefore,  t h e e g u i l i b r i u m and from t h e o p t i m a l close  i n the  which i s near t h e s i z e  trawl  which  time  the  dynamics  of  harvest.  Commencement o f h a r v e s t i n g i n l a t e  September o r e a r l y O c t o b e r i s  suggested  f o r optimal  by t h e f i s h e r y .  affecting  harvesting  exploitation policy  are discussed  Other f a c t o r s  below.  6.4 O t h e r Management C o n s i d e r a t i o n s As  pointed  out  by  the  government  C h a p t e r 5, an  u n r e s t r i c t e d plankton  food  of  supply  herring.  l e v e l s o f plankton which  can  requires  problem, then,  regenerate  themselves  The  models s u c h  level  annually)  of  i s likely  Georgia  euphausiid  several  localities  information  on  harvesting  could  stabilised  for  to  as  i t  would  each  year.  response obtained  certain  and  acceptable  maintain This  stocks  question  application  effect  of  been  the  on  (500 t o n s Strait  i s distributed  recently.  o f the euphausiid  closely  salmon and  permitted  i f the catch  i f  the  i n C h a p t e r 3.  currently  has  Pacific  which  t o have a n e g l i g i b l e populations  reduce  determine  studies  as d i s c u s s e d  harvestinq  the be  field  could  notably  is  harvesting effort  more a t t e n t i o n from  recruitment  fishery  many m a r i n e f i s h e s ,  A central  g u i d e l i n e s quoted i n  harvesting  Most  of over  useful  populations to effort  monitored p o p u l a t i o n s  were  t o allow  166 then  t o approach  e q u i l i b r i u m . The s t o c k  would be more r e a d i l y The  choice  s t u d i e d under these  of t h e best time  t o minimize t h e impact of the harvested  impact should  on  larvae  but  conflict  with  October  to  limited  late  euphausiid  o p t i m a l time  from  harvestinq this  fish  condtions.  o f manaqement, whether i t be  or  With  respect  shellfish,  s p r i n q and summer i n the f a l l  restraint.  minimizinq  plankton  harvestinq  months  Consequently, here  i n the S t r a i t  of harvestinq beinq  to  and w i n t e r  March i s c o n s i d e r e d fishery  harvestinq  p r e d a t o r s o r t o o p t i m i z e t h e body  zooplankton.  of  be r e s t r i c t e d  areas,  on f i s h  relationship  of year f o r plankton  o b v i o u s l y d e p e n d s on t h e p r i o r i t i e s  size  recruitment  early  of  in  nursery  months i s n o t i n the  period  from  t o be s u i t a b l e  for a  Georqia,  in this  period.  with  the  167 CHS PTES 7: SUMMARY  7.1 Summary The  life  Euphausia studied speed  history,  paeifica during  Miller  vertical  Hansen i n t h e S t r a i t  were  examined  frequency  to identify  p o p u l a t i o n s from  of  Georgia.  Inlet,  use o f l o c a l  rearing  was e v a l u a t e d t h r o u g h  throuqh  feeding t r i a l s  in  other  net  selectivity  The  with  Columbia's  i n relation parts  comparison  and t i m e  j u v e n i l e coho  were  by h i g h  SCOR  net  specimens  inferred  fishery and  was  growth r a t e s  and  the  Strait  for fish  samples  and  f o r euphausiids  was  salmon.  micronekton  Factors affecting have  been  fisheries  yield,  such a s  considered  in  w i t h government g u i d e l i n e s f o r p l a n k t o n h a r v e s t i n g . maximum  life  span  of  Inlet  and  the  were p r o d u c e d t o be c l o s e l y  Growth  of  i n the S t r a i t o f  19 months f o r males and  Spawning i n S a a n i c h  Strait  during related  cohorts  E,. p a e i f i c a  t o be a b o u t  May-June and t o a l e s s e r  appeared  paeifica  Jervis Inlet  of harvest,  months f o r f e m a l e s .  larvae  A  c h e m i c a l a n a l y s e s on  o f t h e world.  to  Jervis  of E  t o zooplankton  r e g i o n was f o u n d  during  collected  e u p h a u s i i d s as a f o o d  recent  Georgia 22  region  f o r e u p h a u s i i d s p e c i e s and t o t a l  analysis  Saanich  potential  described  samples,  c o h o r t s and t o c a l c u l a t e  in  British  of Georgia  n e t s , I s a a c s - K i d d mid-water t r a w l a n d by  hauls  The  and p o p u l a t i o n d y n a m i c s o f  1974-76. Z o o p l a n k t o n  biomass. Length used  distribution  extent of  in  was m a i n l y  August-September.  In  Georgia, s e v e r a l cohorts of  May-September.  Spawning  to phytoplankton  was w e l l  Inlet  up  d e s c r i b e d by  activity  abundance. von B e r t a l a n f f y  168 growth e q u a t i o n s ; mm/day) of  durinq  qrowth o f  rapid  (0.094  summer b u t s l o w e d d u r i n q autumn a t body  lenqths  15-17 mm and s t o p p e d  similar  sprinq  i n winter.  pattern. D i f f e r e n t i a l  apparent;  males had h i q h e r  selective appeared  cohorts  Second-year qrowth  showed  a  qrowth and m o r t a l i t y o f s e x e s was  qrowth r a t e s  mortality followinq early t o qrow s l o w e r  was  i n lenqth  and  experienced  maturity(11-12  mm).  a t peak r e p r o d u c t i v e  sizeFemales  sizes{14-  16 mm and 19-21 mm). Survival  was  lowest  staqes(6%/mo)  but  increased  staqes(4.6 15%/mo mm)  life  and j u v e n i l e  nearly  distribution 19-20  P, the  18mm)  3,0.  a  larval  mm)  f o r both  Durinq  Total  1975, class  J .Survival  sexes over peaks  in  occurred  biomass,  B,  I n l e t d u r i n q July-November value  for  of  P/B  of  (8-12 larqe  10 mm the  body  annual  a t 11, 16-17 and  herbivorous  o f E. p a c i f i c a  shallow  copepods  dusk  and w i n t e r .  over  2  q/m . 3  The  wet  was  26,8  but  mqC/m /day; 2  i s similar to  hiqher  than  a  .  sound s c a t t e r i n q after  in  was 8,8# which  at  l a y e r s of meqazooplankton 107  I n l e t s and i n p a r t s o f the S t r a i t  qenerally  to juvenile  10-  production,  were r e c o r d e d  fall  r a t e i n c r e a s e d by  maximum i n O c t o b e r - N o v e m b e r . E. p a c i f i c a  previous estimate  durinq  larval  population  values reported  Jervis  larval  each  correspondinq  (> 5mm)  early  declined sharply.  o f b i o m a s s by s i z e  i n Saanich  Dense,  and  40%/mo f o r l a t e  survival  exponent  mm body l e n q t h .  reached  about  to small adult(12-14  lenqth:weiqht was  eqq  phase chanqes [ l a t e  males and f e m a l e s (over  lenqth  to  t o 8mm), S u b s e q u e n t l y  with  The  between  biomass  kHz  in  Saanich  of Georqia, in  such  and  especially layers  was  169 Juvenile 3.8%/day on 3.1%/day  diets  Oregon M o i s t  carotenoid  indicated between  and  of  as  and  by  dynamics.  and  harvesting who  Local  ^»g/g  euphausiids  and  have  a  high  making  them  harvested  about  100  main u s e s a r e a s an  aguaculture.  for  need f u r t h e r i n f o r m a t i o n  paeifica  from J a n u a r y t o  fishery  t o have p o t e n t i a l to  E.  plankton  monitored euphausiid  and  aguarium  management c o n s i d e r a t i o n s have  December r a t h e r t h a n  industry  and  p r o t e i n s and  tissue),  fishery  the  other  appears  2.7%  of  feeds.  g o v e r n m e n t g u i d e l i n e s on  region  rates  meal, f r o z e n e u p h a u s i i d s  optimal h a r v e s t i n g time  carefully  Georgia  fisheries  1977;  3.0%,  a d i e t a r y supplement i n salmon  that the October  plankton  early  c a l c u l a t i o n s and  as s u g g e s t e d limited  (80-219  in aguacultural  during  compared t o  o f amino a c i d s i n t h e i r  Columbia's e u p h a u s i i d  tons  Yield  9 C showed mean growth  respectively.  spectrum  f o r use  food  at  euphausiid  concentrations  British  fish  of  Pellet,  well-balanced  metric  salmon  freeze-dried euphausiids  on  suitable  coho  managers  March  harvesting. i n the  value of  on z o o p l a n k t o n  is  A  Strait  t o the  new  associated population  170 BIBLIOGRAPHY ALLEN,  K.R. 1971. 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WP-  WP-  2  (Working P a r t y No. 2) 1968. S m a l l e r m e s o p l a n k t o n . R e p o r t o f Working P a r t y No. 2. I n : Z o o p l a n k t o n sampling. Monographs on O c e a n o g r a p h i c M e t h o d o l o g y 2. UNESCO, P a r i s p. 153-59.  4 (Working P a r t y No. 4) 1 968. P a r t y No. 4 I n : Z o o p l a n k t o n Oceanographic Methodology 167.  M i c r o n e k t o n . R e p o r t o f Working S a m p l i n g . Monographs on 2. UNESCO, P a r i s p.164-  183  APPENDIX A  T a b l e 23. L i s t  o f 1975 c r u i s e s ,  Cruise  Date 20,21 J a n . 17,18 F e b . 17-20 Mar. 24,25 Mar. 1-4 Apr. 27,2 8 A p r . 12,13 May 16-20 J u n 16-18 J u l y 21-22 J u l y 19-22 Aug. 3,4 S e p t . 6-8 O c t .  75/3 75/5 75/10 75/11 75/12 75/13 75/15 75/21 75/24 75/25 75/27 75/29 75/31  3-5  Nov.  75/33  1-4  Dec.  75/34  No..  with dates  and d e s t i n a t i o n s .  Destination Saanich I n l e t Saanich I n l e t Knight I n l e t , S t r a i t o f Georgia S a a n i c h I n l e t , Howe Sound S t r a i t o f Georgia, J e r v i s I n l e t Saanich I n l e t Saanich Inlet S t r a i t of Georgia, J e r v i s Inlet S t r a i t o f Georgia, J e r v i s I n l e t Saanich I n l e t S t r a i t of Georgia, Saanich I n l e t S t r a i t of Georgia, J e r v i s Inlet J e r v i s I n l e t , S t r a i t of Georgia, Saanich I n l e t J e r v i s I n l e t , S t r a i t o f Georgia, Saanich I n l e t Jervis Inlet  184  FIGURE 44. C r u i s e t r a c k s f o r s u r v e y c r u i s e s 75/27 " (August) 75/29 {September) .  and  FIGURE  45. C r u i s e t r a c k s 75/33 (November).  f o r s u r v e y c r u i s e s 75/31  ( O c t o b e r ) and  

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