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The effect of intertidal exposure on the survival and embryonic development of Pacific herring spawn Jones, Barry Cyril 1971

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THE EFFECT OF INTERTIDAL EXPOSURE ON THE SURVIVAL AND EMBRYONIC DEVELOPMENT OF PACIFIC HERRING SPAM by BARRY CYRIL JONES B.Sc,  University of B r i t i s h Columbia, 1965  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in the Department of Zoology  We accept t h i s thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA November, 1971  In p r e s e n t i n g an the  in partial  advanced degree a t t h e U n i v e r s i t y Library  I further for  this thesis  shall  f u l f i l m e n t of the requirements f o r of British  make i t f r e e l y a v a i l a b l e  agree that  permission  Columbia,  f o rreference  f o r extensive  I agree  that  and s t u d y .  copying of t h i s  thesis  s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r  by  h i s representatives.  of  this thesis  written  I t i s understood  f o r f i n a n c i a l gain  permission.  Department o f  ZOOLOGY  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  Columbia  November 26, 1971.  shall  that  copying or p u b l i c a t i o n  n o t be a l l o w e d w i t h o u t  my  ABSTRACT  Eggs of P a c i f i c h e r r i n g were exposed to a i r f o r different  p e r i o d s of time i n s i m u l a t i o n of t i d a l  on spawn d e p o s i t s at v a r y i n g beach h e i g h t s .  effects  The maximum  exposure range was 2/3 of a 2k hour day c o r r e s p o n d i n g roughly to the exposure of eggs at k meters above mean low t i d e on the B r i t i s h Columbia c o a s t . f i s h length,  Egg s i z e ,  and egg clump s i z e were examined as  f a c t o r s modifying the e f f e c t  of exposure.  spawning  secondary  Incubation time  dropped from 19 to 18 days with only two 2-hour p e r i o d s of exposure per day and t h e r e a f t e r  fell  slowly.  It i s  suggested  t h a t oxygen d e p r i v a t i o n t r i g g e r e d a h a t c h i n g response  for  the i n i t i a l drop, whereas the gradual decrease was due to a h i g h e r a i r temperature i n c r e a s i n g metabolism. m o r t a l i t y rose s t e a d i l y maximum exposure time,  Hatching  from an unexposed 1J% to yi% at with s i g n i f i c a n t l y h i g h e r  contributions  from eggs of s m a l l e r f i s h and s m a l l e r egg clumps.  Larval  l e n g t h at h a t c h i n g f o r the unexposed eggs was 7*7 mm.5 l e n g t h s f o r a l l degrees of exposure were s i m i l a r (7% l e s s than f o r no exposure).  L a r v a l weight  remained r e l a t i v e l y constant exposure p e r i o d when i t  (body plus y o l k )  (0.099 mg.) u n t i l the l o n g e s t  dropped to O.O87 mg.  This  decrease  c o i n c i d e d w i t h s i m i l a r sharp trends i n i n c u b a t i o n time and h a t c h i n g m o r t a l i t y , and suggests a " c r i t i c a l p o i n t " near the upper experimental range of exposure, little  chance of normal development  above which eggs stand  or s u r v i v a l .  Beach  surveys to note p o s s i b l e  egg s i z e s t r a t i f i c a t i o n ,  although  s u g g e s t i n g the d e p o s i t i o n of l a r g e r eggs a t the top l e v e l s , proved i n c o n c l u s i v e ,  but p o i n t up the p o s s i b i l i t y that a  heavy f i s h i n g pressure which reduces mean f i s h s i z e might detrimentally affect intertidal  potential  exposure e f f e c t  stock r e c r u i t m e n t v i a  on the  spawn.  the  iii TABLE OF CONTENTS  Page ABSTRACT  i  LIST OF TABLES  iv  LIST OF FIGURES ACKNOWLEDGEMENTS  v •  vii  INTRODUCTION  1  MATERIALS AND METHODS  3  Spawner Characteristics Analyses.-  3  Exposure Laboratory Experiment  5  Egg Size D i s t r i b u t i o n Beach Surveys  9 10  RESULTS Effects of Exposure  10  Incubation Time  12  Hatching Mortality  12  Larval Length  15  Larval Weight  15  Beach S t r a t i f i c a t i o n  18  DISCUSSION  18  LITERATURE CITED  26  APPENDICES  29  A - Apparatus Design  30  B - Raw Data  33  C - Spawner Correlations  ^2  D - Computations Summary E - S t a t i s t i c a l Analyses  52  iv LIST OF TABLES  Table  Page  I  Summary of experimental conditions  II  Group means and standard deviations i n the analyses  6 11  Appendix Table 36  IA  Spawner data l i s t  IIA  Incubator data l i s t  IIIA  Computations f o r incubation time (days)  ^7  IVA  Computations f o r hatching mortality {%)  ^8  VA  Computations f o r l a r v a l length  ^9  VIA  Computations f o r l a r v a l weight (mg;..)  50  VILA.  Computations f o r beach s t r a t i f i c a t i o n of egg weight (mg.), showing beach height (m. ) Significance of differences within the  50  VIIIA  37  •  (mm.)  t o t a l data  53  IXA  Significance of differences between groups  5^  XA  Significance of i n t e r a c t i o n  55  XIA  Significance of differences between beach levels  56  v LIST OF FIGURES  Figure 1  2 3 k 5 6 7 8 9 10 11  12  Page Relationship of beach height to exposure time. Data f o r Vancouver, B.C., (March, 1970) meaned from S t r a i t s Towing calendar  6  Relationship of incubation time to exposure time for t o t a l data  13  Relationship of hatching mortality to exposure time f o r t o t a l data  13  Fish length effects i n the relationship between hatching mortality and exposure time  Ik  Clump size effects i n the relationship between hatching mortality and exposure time  Ik  Relationship of l a r v a l length to exposure time f o r t o t a l data  16  Egg size effects i n the r e l a t i o n s h i p between l a r v a l length and exposure time.....  16  Relationship of l a r v a l weight to exposure time f o r t o t a l data  17  Egg size effects i n the relationship between l a r v a l weight and exposure time  17  Relationship of egg size to beach height at spawning, Bedwell Bay, A p r i l 20, 1970  19  Relationship of egg size to beach height at mid-incubation (8'days), Nanoose Bay, March 27, 1970  19  Relationship of egg size to beach height just a f t e r spawning (k days) and at hatching (16 days) f o r the same egg mass. The l a t t e r i s f o r larvae as the eggs hatched en route to the lab. These samples taken at Icarus Point, March 17 and 29, 1971  20  LIST OF FIGURES (CONT.)  Appendix Figure  Page  1A  Tank set-up f o r each exposure time  32  2A  Cross-section of incubator i n tank  32  3A  Relationship of egg size to spawner length  43  4A  Relationship of egg size to spawner weight with gonads removed  5A  Relationship of egg size to spawner age  6A  Relationship of spawner length to age  7A  Relationship removed Relationship removed  8A  of to of to  spawner weight with gonads age spawner weight with gonads length  43  kk 45 45  vii ACKNOWLEDGEMENTS  I would l i k e to thank D r . P . A . L a r k i n , of  my s u p e r v i s o r ,  the Department of Zoology, U n i v e r s i t y of B r i t i s h Columbia,  who gave me the o p p o r t u n i t y ,  support from h i s N a t i o n a l Research  C o u n c i l g r a n t , and guidance i n t h i s work over the past two years.  The a s s i s t a n c e of D r . F . H . C .  T a y l o r and the  members of h i s H e r r i n g I n v e s t i g a t i o n group of the  other  Fisheries  Research Board of Canada's B i o l o g i c a l S t a t i o n , Nanaimo, also gratefully appreciated. facilities,  the f i s h ,  They s u p p l i e d me with  is  the  and checked, c e r t a i n of my d a t a .  Thanks  a l s o go to Dr. N . G i l b e r t f o r h i s h e l p i n the s e t - u p and use of and  h i s non-orthogonal a n a l y s i s  of v a r i a n c e computer program  to Dr. D . J . R a n d a l l f o r h i s h e l p f u l c r i t i c i s m s of the manu-  script.  D r s . G i l b e r t and Randall are of the Department of  Zoology, U n i v e r s i t y of B . C .  THE EFFECT OF INTERTIDAL EXPOSURE ON THE SURVIVAL AND EMBRYONIC DEVELOPMENT OF PACIFIC HERRING SPAWN  INTRODUCTION The are  eggs of the P a c i f i c h e r r i n g  (Clupea p a l l a s i i V a l . )  spawned i n and below the i n t e r t i d a l zone.  Due to  their  adhesive n a t u r e , they become a t t a c h e d to c e r t a i n forms-of seaweed and are e s s e n t i a l l y of  immobile.  For t h i s  reason most  them are s u b j e c t e d to r e g u l a r p e r i o d s of exposure and sub-  mergence.  Such c o n d i t i o n s cause c o n s i d e r a b l e f l u c t u a t i o n  i n the environment of the eggs and may a f f e c t and development.  The e f f e c t of thi>s  their  fluctuation  survival is  o s t e n s i b l y d i r e c t l y r e l a t e d to the height up the beach that the eggs a r e l a i d ,  and t h u s ,  the amount of time they a r e  exposed. W i t h i n the spawning zone a v a r i e t y of egg s i z e s can be expected because each spawner produces a range of sizes  ( f o r example,  for Atlantic herring,  Hempel and B l a x t e r , 1 9 6 7 ) .  egg  Clupea harengus,  In a d d i t i o n , every r e p r o d u c t i v e  stock comprises a v a r i e t y of i n d i v i d u a l s d i f f e r i n g i n l e n g t h , weight,  and age,  and s e v e r a l s t u d i e s  (Rannak, 1 9 5 8 ; B l a x t e r  and Hempel, 1 9 ^ 3 ) have shown that mean egg s i z e i s a f u n c t i o n of  s i z e and m a t u r i t y .  The adhesiveness  of h e r r i n g eggs a l s o  causes the formation of clumps when exposed to sea water. Such clumps are of d i f f e r i n g t h i c k n e s s and vary i n egg and number.  Hence, egg s i z e ,  fish size,  size  and clump s i z e a l l  2 have some b e a r i n g on the p o s s i b l e  e f f e c t s of  environmental  f l u c t u a t i o n r e s u l t i n g from exposure. The c h a r a c t e r i s t i c s most n o t a b l y a f f e c t e d time,  h a t c h i n g m o r t a l i t y , and l a r v a l l e n g t h and weight a t  hatching. that  are incubation  In t h i s  r e g a r d , B l a x t e r and Hempel (1963) noted  egg s i z e d i d not a f f e c t  i n c u b a t i o n time, whereas h a t c h i n g  m o r t a l i t y was found by other s t u d i e s  (Runnstrom, 19^1; McMynn  and Hoar, 1953) to be d i r e c t l y r e l a t e d to egg number. l a r v a e have been shown to be a f f e c t e d sizes.  For instance,  The  by both egg and f i s h  Toom (1958) has demonstrated that  s i z e i s d i r e c t l y r e l a t e d to egg s i z e ,  larval  and Cushing and B r i d g e r  (I966) have noted that l a r v a e from f i r s t spawners are l e s s v i a b l e than those from l a r g e r f i s h .  In a d d i t i o n , i t has a l s o  been shown (Nagasaki, 1958) t h a t f e c u n d i t y i s d i r e c t l y to spawner  related  size.  Because f i s h i n g i n t e n s i t y  reduced the mean s i z e ,  age,  and numbers of spawners of B r i t i s h Columbia stocks of h e r r i n g (Taylor,  1963) and North Sea h e r r i n g , Clupea harengus  (Cushing and B r i d g e r ,  1966), then i t must f o l l o w that mean  egg s i z e a l s o decreased.  There would be fewer,  eggs produced than i n former y e a r s , of l a r v a l s u r v i v a l . fish  smaller  and w i t h a l e s s e r  chance  The s u r v i v a l advantage a c c r u i n g to a  stock due to the presence  of l a r g e r eggs and l a r v a e  has been p o i n t e d out by M a r s h a l l  (1953)-  If  environmental  f a c t o r s o p e r a t i n g i n the spawning zone a r e more d e t r i m e n t a l to s m a l l e r eggs o r the eggs from s m a l l e r f i s h , c o u l d be s e r i o u s  repercussions  on r e c r u i t m e n t  then  there  potential,  3 i.e.  the number of immature f i s h a v a i l a b l e to  enter  the  reproductive population. Previous work on h e r r i n g egg development  has  concerned w i t h c o n d i t i o n s f o r submerged eggs. sought  to examine i n c u b a t i o n time,  been  This  study-  h a t c h i n g m o r t a l i t y , and  l a r v a l l e n g t h and weight a t h a t c h i n g i n r e l a t i o n to v a r y i n g degrees of exposure.  The l a b o r a t o r y experiment was  conducted  and a n a l y z e d u s i n g as a d d i t i o n a l v a r i a b l e s the e f f e c t s egg s i z e ,  fish size,  and clump s i z e .  a l s o undertaken to note p o s s i b l e  of  A beach survey was  egg s i z e  stratification.  MATERIALS AND METHODS The  eggs used i n t h i s  study were taken from spawning  P a c i f i c h e r r i n g of the Lower East Coast stock Vancouver I s l a n d r e g i o n )  (inner  southern  of B r i t i s h Columbia, and the l a b o r a -  t o r y experiment was done a t the F i s h e r i e s Research Board of Canada's B i o l o g i c a l S t a t i o n i n Nanaimo, B . C .  Spawner C h a r a c t e r i s t i c s Analyses F o r t y female  spawners were used to determine i f  s i z e was r e l a t e d to f i s h s i z e and m a t u r i t y .  The f i r s t  taken by beach seine and h e l d a l i v e i n l a r g e , h o l d i n g tanks f o r one week p r i o r to use.  used i:mmedlately.  29 were  well-flushed  The other 1 1 were  o b t a i n e d dead from l o c a l t r a w l e r s w i t h i n 6 hours of and  egg  capture  A f t e r s t r i p p i n g the experimental  the spawners were measured f o r standard l e n g t h  ( t i p of  to end of v e r t e b r a l column) and three or more s c a l e s  eggs, snout  plus  4 both o t o l i t h s were taken f o r age d e t e r m i n a t i o n s .  The gonads  were then removed and the spawner wet weight r e c o r d e d .  The  f i s h were then tagged and preserved i n 5$ f o r m a l i n f o r possible future  reference.  The age of each spawner was determined by r e a d i n g the s c a l e s from the areas above and below the l a t e r a l l i n e the r e a r of the g i l l ( T e s t e r , 1937). glass s l i d e . and hence,  cover and the f r o n t of the d o r s a l f i n  These were c l e a n e d , dyed, and mounted on a  The 11 t r a w l caught f i s h had very few  any s c a l e was used.  the o t o l i t h s  between  scales,  These ages were checked with  which had been cleaned and preserved i n 5$ forma-  lin. Samples of each spawners' gonads were immediately p r e served i n S% f o r m a l i n when removed.  T h i s succeeded  in  hardening and s e p a r a t i n g the eggs from each o t h e r and the o v a r i a n t i s s u e so that they c o u l d be e a s i l y sequently,  counted.  Sub-  the gonad samples were broken up to r e l e a s e  which were then thoroughly washed i n f r e s h water.  the eggs  Five  samples of 100 eggs were taken from each of two f i s h and put i n a d r y i n g oven f o r 24 hours a t 50° C e n t r i g r a d e ^ .  Several  p r i o r t e s t s confirmed that t h e r e were no e f f e c t s of  position  of  samples i n the d r y e r ,  the d r y e r h a n d l i n g c a p a c i t y ,  e s t i m a t i o n 'Of r e s i d u e weight,  and the l e n g t h of d r y i n g time.  The samples were i n d i v i d u a l l y removed from the oven, on a Cenco e l e c t r i c a l balance to the n e a r e s t 1  the  weighed  0.1 mg., weighed  These c o n d i t i o n s a r e the same as those used by B l a x t e r and Hempel (1963 ).  again as a check,  5  and then d i s c a r d e d .  Exposure L a b o r a t o r y Experiment F i v e tanks  (see  d i f f e r e n t beach l e v e l s  Appendix A) s i m u l a t e d c o n d i t i o n s (Figure 1) r a n g i n g from the  at  control  (0) which was c o n t i n u o u s l y submerged, through 2, 4, 6, and 8 hours of exposure twice per day.  These exposure  s i m u l a t e a f i x e d t i d a l c y c l e of roughly 2 meters  times  amplitude  (not found i n t h i s a r e a , but necessary as an experimental feature).  Each tank contained f o r t y i n c u b a t o r s , and a l l were  kept i n a small t e m p e r a t u r e - c o n t r o l l e d room under r e g u l a t e d conditions  (Table 1).  From every female spawner approximately 100 eggs s t r i p p e d i n t o each of f i v e operation,  separate  incubators.  clumping of the eggs was u n a v o i d a b l e ,  In  were  this  but an  <$  attempt was made to produce the same clump form i n a l l incubators.  The i n c u b a t o r s were then s i m u l t a n e o u s l y  placed  i n t o a g l a s s f e r t i l i z a t i o n t r a y c o n t a i n i n g a sperm s o l u t i o n and allowed to stand f o r 60 seconds.  The sperm s o l u t i o n  was prepared u s i n g 500 ml. of sea water and s u f f i c i e n t  sperm  from 2 o r 3 males  water  opaque.  (to  ensure v i a b l e sperm) to t u r n the  The i n c u b a t o r s were t r a n s f e r r e d to another t r a y  and g e n t l y f l u s h e d w i t h f r e s h sea water to prevent  polyspermy  and remove any excess o r g a n i c matter which might decay i n the tanks.  They were then t r a n s f e r r e d to t h e i r  respective  exposure tanks and kept submerged f o r 12 hours before  the  The small s i z e and adhesiveness of the eggs prevented counting. In f a c t , i t was found that the mean was 132 eggs; standard d e v i a t i o n t kj,.  6  Exposure time twice per day F i g u r e 1:  Table 1:  (hr.)  R e l a t i o n s h i p of beach h e i g h t to exposure time. Data f o r Vancouver, B . C . , (March, 1970) meaned from S t r a i t s Towing c a l e n d a r .  Summary of  experimental  conditions.  Factor  (1) L i g h t (a) (b)  Mean  • •  Day l e n g t h Intensity  (2) A i r : — T a ) Temperature (b) R e l a t i v e  (3) Sea Water*  humidity  (a) Temperature (b) Oxygen (c) Flow r a t e (d)  Standard Dev.(SD)  Depth  13 hours 60 watt bulb at 75 cm. above each tank  —  11.7° C  to. 6°  65%  t5%  7.8° C  +0.4°  55ml. per min.  ±3 m l .  6.5 m l . / I .  per i n c u b a t o r 5 cm.  7 experimental c o n d i t i o n s were  initiated.  The a r t i f i c i a l environment  (summarized i n T a b l e I)  was  s i m i l a r to t h a t recorded on the beach surveys d u r i n g the experimental i n c u b a t i o n p e r i o d .  An attempt was made to main-  t a i n the l a b o r a t o r y temperature at 12° C.  A maximum-minimum  thermometer checked d a i l y gave a mean of 11.7° G; SD * 0.6°. The mean r e l a t i v e humidity determined by s l i n g  psychrometer  was 65%', SD * 5%> The day l e n g t h was r e g u l a t e d by time c l o c k and set  at t h i r t e e n hours (9 am to 10 pm) so that one  p e r i o d was i n the l i g h t and the other i n darkness. source was a s i n g l e  60-watt incandescent  The l i g h t  b u l b per tank.  b u l b had a white p o r c e l a i n r e a r r e f l e c t o r and was 75 cm. above the l e v e l  exposure  Each  suspended  of the eggs i n the center of the tank.  The sea water o r i g i n a t e d from the bottom of the l o c a l bay and ran c o n t i n u o u s l y through the tanks at a mean r a t e of 55 l • m  per minute per i n c u b a t o r ; SD * 3 nil. full,  When the tanks were  a l l the eggs were suspended at an equal depth of 5 cm.  S e v e r a l oxygen determinations were c a r r i e d out on the and o u t l e t  waters by the Improved Winkler Method and a l l came  to approximately 6.5 m l . per 1. plentiful system,  inlet  T h i s would suggest that  with  oxygen i n the i n l e t waters and the open c i r c u l a t o r y  oxygen was not a l i m i t i n g factor-^.  temperature measurements  Regular water  y i e l d e d a mean of 7•8° C; SD - 0.4°.  T h i s r e s u l t e d i n an a i r / w a t e r temperature d i f f e r e n t i a l of 4° C. 3  T h i s was v e r i f i e d by a tank p o s i t i o n a n a l y s i s of the r e s u l t s u s i n g Dr. N . G i l b e r t ' s program. However, because the system was open and a p p r o p r i a t e water sampling proved d i f f i c u l t , I would q u e s t i o n the v a l i d i t y of these d e t e r m i n a t i o n s , although not the c o n c l u s i o n s drawn.  8  A f t e r 15 days the larvae "began to hatch.  Throughout  the hatching period c o l l e c t i o n was done immediately p r i o r to exposure (10 am and 10 pm) of the eggs . Upon removal by large-mouth pipette, they were immobilized i n a 1:50,000 solution of MS222 (Tricaine Methanesulfonate). caused the larvae to straighten out and s t i f f e n . then preserved i n 5% formalin.  This treatment They were  When l a r v a l emergence ceased,  the incubators were cleaned out and the dead eggs counted-'. Prom t h i s data the incubation time (from f e r t i l i z a t i o n to 50$ hatch) and mortality were determined.  At convenient times  during and a f t e r the experiment the larvae were counted and the lengths (from t i p of snout to end of t a i l ) of a l l measurable larvae were determined by graduated microscopic eyepiece. This work took some 3 months, during which time a companion shrinkage test was run.  When the measuring was completed,  the test was terminated and a table of d a i l y shrinkage correction values was computed and used to correct the mean l a r v a l length obtained f o r each incubator.  The shrinkage  was found to be only U-,2% over the entire three month measuring period.  Once the larvae from each incubator had  been counted and measured, they were a l l put into one v i a l . When a l l the incubators had been processed i n t h i s way, ten v i a l s (incubators) at a time were taken, the larvae recounted, washed thoroughly i n fresh water, and dried and weighed i n  Larvae did not hatch out during the exposure periods. The dead larvae were i n many stages of development.  the same manner as f o r the spawner egg weights  6 7  ' .  Egg S i z e D i s t r i b u t i o n Beach Surveys A number of r e c e n t spawning s i t e s were examined d u r i n g daytime low t i d e s .  For purposes of comparison, the  deter-  m i n a t i o n of beach height was based on the datum e s t a b l i s h e d by the sea l e v e l a t the exact time of low t i d e  (as i n d i c a t e d  i n the Canadian T i d e and Current Tables - #5, u s i n g P o i n t A t k i n s o n as a r e f e r e n c e ) .  The sea l e v e l a t t h i s time was  used as sample area M, the middle r e g i o n of f i v e beach l e v e l s sampled on each survey.  The bottom sample (B) was then taken  i n as great a depth as p r a c t i c a l  (about 1 m e t e r ) , and another  sample (L-low) taken halfway between these two (about 50 c m . ) . The a c t u a l sample depths were determined w i t h a graduated staff.  Two f u r t h e r samples were taken above M — T ( t o p ) ,  as h i g h as the spawn was d e p o s i t e d , between T and M.  as  halfway  The h e i g h t s of these were determined by  c l i n o m e t e r and tape measure. jars,  and H ( h i g h ) ,  The samples,  taken i n 500 ml.  i n c l u d e d as many eggs and the seaweed they adhered to  possible. Environmental c o n d i t i o n s were a l s o r e c o r d e d at  spawning s i t e s .  the  Among these were the a i r and sea water  F i x a t i o n i n f o r m a l i n over a three month p e r i o d was shown to have n e g l i g i b l e e f f e c t s on l a r v a l weight (-0.4$) and egg weight {-0.2%) by B l a x t e r and Hempel ( 1 9 6 6 ) . L a r v a l weight i n t h i s experiment means the t o t a l weight the body and the y o l k sac.  of  10 temperature, and r e l a t i v e humidity as determined by s l i n g psychrometer. mental  These data were used as a guide f o r the  experi-  regime.  Upon r e t u r n i n g to the l a b , the age of the spawn was estimated  (Outram, 1955)« the samples were preserved i n 5%  formalin,  and the beach l e v e l  low t i d e was c a l c u l a t e d .  f o r each sample r e l a t i v e to mean  Later,  the eggs were separated from  the seaweed by t r a n s f e r to a one normal KOH s o l u t i o n which was then heated to 30° C. and allowed to stand f o r 2 h o u r s ® . The  eggs and seaweed were then t r a n s f e r r e d to a 5% f o r m a l i n  s o l u t i o n a g a i n to harden f o r 24 hours before the seaweed was removed and d i s c a r d e d .  T h i s treatment not o n l y loosened  eggs from the seaweed, but a l s o from each o t h e r . then thoroughly washed i n f r e s h water, were taken from each beach l e v e l the spawner egg weight  the  The eggs were  and ten 100-egg  samples  f o r d r y i n g and weighing as per  determinations.  RESULTS  E f f e c t s of Exposure Eggs from s i x of the t r a w l caught f i s h had 100^ m o r t a l i t y i n a l l tanks.  The data from these i n c u b a t o r s was  d i s c a r d e d on the grounds that d i s i n t e g r a t i n g when used.  the eggs were probably a l r e a d y  Data f o r one spawner from the  beach s e i n e group was d i s c a r d e d f o r the same r e a s o n . Q  The net  Procedure by word-of-mouth from h e r r i n g r e s e a r c h e r s at B i o l o g i c a l S t a t i o n , Nanaimo, but s l i g h t l y a l t e r e d .  the  11 r e s u l t was data from 3 3 spawners.  On c o n s i d e r a t i o n ,  the  experimental data was d i v i d e d i n t o t h r e e groups — noted as s m a l l , medium, and l a r g e . i n the a n a l y s e s  (see Appendix D).  The data were i n i t i a l l y a n a l y s e d i n t o t a l to note g e n e r a l t r e n d of each c h a r a c t e r i s t i c i n r e l a t i o n to exposure time.  the  increased  They were then t r e a t e d s e p a r a t e l y a c c o r d i n g  to t h e i r groupings as noted above. Egg s i z e as determined from the preserved gonads was first  examined f o r p o s s i b l e d i f f e r e n c e s  between groups.  It  was found of s i g n i f i c a n c e o n l y i n l a r v a l l e n g t h and weight (see Appendix E ) . of  f i s h length.  The second a n a l y s i s  examined the  Here h a t c h i n g m o r t a l i t y and l a r v a l  were shown to be a f f e c t e d .  effects weight  Since f i s h l e n g t h and weight  are  so h i g h l y c o r r e l a t e d (see Appendix C ) , the a n a l y s i s was not repeated f o r weight.  The e f f e c t  of age was not examined as  the spawners were predominantly 3 - y e a r o l d f i s h , a few 4 and 5 - y e a r o l d s . was d i f f e r e n t if  with o n l y  Because the egg number (clump s i z e )  f o r each i n c u b a t o r , a t h i r d t e s t was run to  t h i s had any e f f e c t .  I t proved n e g l i g i b l e  c h a r a c t e r i s t i c s but h a t c h i n g m o r t a l i t y .  for a l l  The mean group  values f o r these t h r e e a n a l y s e s are g i v e n i n Table  Table I I :  Group means and standard d e v i a t i o n s  Grouping (1)  Egg s i z e  (mg.)  (2) Pish length ( 3 ) Clump S i z e  (mm.) (no.)  see  II.  i n the  analyses.  Small  Medium  Large  0 . 2 4 3 * 0 . 015  0.271*0.005  0.300*0.015  199*5 89*17  211±4  223±6  130±12  175*29  12 Another analysis was performed to determine i f there was any interaction among egg size, f i s h length, and clump size.  This was  found to be non-significant i n most cases for  a l l factors and hence w i l l not be referred to further. These various analyses are discussed together for each of the variables examined.  Incubation Time The relationship of incubation time to exposure time i s shown i n Figure 2.  The control or unexposed incubators  had a s l i g h t l y greater than 19-day incubation period.  The  f i r s t exposure period (2 hours) showed an abrupt decrease of close to one f u l l day  (p < . 0 1 ) .  Thereafter, there i s only  a gradual decrease through the remaining exposure periods, but the t o t a l decrease significant  (p =  (from 2 to 8 hours) of 0.4 days i s  .01-.05).  Hatching Mortality As expected,  the hatching mortality showed a  increase with increasing exposure time (Figure 3 ) .  continuous rising  from 13$ i n the control to 31$ i n the 8-hour exposure period. For the t o t a l data, t h i s i s s i g n i f i c a n t (p < . 0 1 ) 9 . Eggs from smaller f i s h had a higher mortality (Figure 4), but the effect was not s t a t i s t i c a l l y s i g n i f i c a n t (p =  .05-.10).  Analysis of t h i s small f i s h data did not indicate which egg 9  A l l hatching mortality s t a t i s t i c a l tests were done on a r c s i n transformation of the percentage data.  13 19-5 •  17. 0 • 0 Figure 2:  2 4 6 Exposure time twice per day (hr.) R e l a t i o n s h i p of i n c u b a t i o n time to exposure f o r t o t a l data.  8 time  53%T  0 Figure 3  8  2 4 6 Exposure time twice per day (hr.) R e l a t i o n s h i p o f h a t c h i n g m o r t a l i t y to time f o r t o t a l data.  8  exposure  14 40  >5  •P •H  H  30  03 P  o g  to  20  •H  -C o -p  03  m  medium f i s h  10 •  )  4  2  8  Exposure time twice per day ( h r . ) F i s h l e n g t h e f f e c t s i n the r e l a t i o n s h i p between h a t c h i n g m o r t a l i t y and exposure time.  F i g u r e 4:  40 small -P  clumps  30  o3  -p u o  g  faD  fl  20  •H  .c o p  03  K  10  large  6 F i g u r e 5«  2  clumps  5  Exposure time twice per day  6"  (hr.)  Clump s i z e e f f e c t s i n the r e l a t i o n s h i p between h a t c h i n g m o r t a l i t y and exposure time.  8"  sizes within the group might be s u f f e r i n g greater mortality. Smaller egg clumps also had a s i g n i f i c a n t l y higher mortality (p < .01 f o r several exposure periods) than larger egg clumps (Figure 5 ) .  Larval Length Larval length at hatching i n r e l a t i o n to the exposure time (Figure 6) follows c l o s e l y the pattern of incubation time. The i n i t i a l drop between the control and the 2-hour exposure periods from 7.7 mm.  to 7-2 mm.  i s s i g n i f i c a n t (p < . 0 1 ) .  From exposure periods of 2 to 8 hours there was no further, decrease. Larvae were shorter (Figure 7) from smaller eggs, but t h i s difference was not s i g n i f i c a n t (p =  .05-.10).  Larval Weight The r e l a t i o n s h i p of l a r v a l weight to exposure time (Figure 8) follows a concave curve, r i s i n g from 0.092 mg. to a high of 0.099 mg. at the 4-hour period, and f a l l i n g back to 0.087 mg. by the 8-hour period.  None of the differences was  s t a t i s t i c a l l y significant. For egg size groups (Figure 9) there was a pronounced (p < .01) r e l a t i o n s h i p to l a r v a l weight.  F i s h length had  similar effects (not shown), except that they were not s i g n i f i c a n t (p =  .05-.10).  16  8.5  8.0 Xi •p  faO  fl) 7 . 5  I-H  iH f-l  5  7.0  6.5  )  Figure  6:  4"  2  Exposure  R e l a t i o n s h i p of l a r v a l f o r t o t a l data.  8  6  t i m e t w i c e p e r day  (hr.)  l e n g t h to exposure  time  8.5  8.0 xi •p  bD  C 0  r-n  7-5  rH  cd l-H  7.0  small  eggs-  6.5  0  Figure 7 *  Exposure  t i m e t w i c e p e r day  (hr.)  Egg s i z e e f f e c t s i n t h e r e l a t i o n s h i p l a r v a l l e n g t h and exposure t i m e .  between  17  0.12  s  0.10  .p  s: bO •H <D  DS  0. 08  ts  H  rH  0.06  2 4 6 Exposure time twice per day (hr.)  0 Figure 8:  8  R e l a t i o n s h i p of l a r v a l weight to exposure time f o r t o t a l data.  0.12  large  eggs  s 0.10  p  Si 60 •H <D  ts rH  0. 08  IS rH  a  o. 06  ~0~ Figure 9:  2 4 6 Exposure time twice per day (hr.)  Egg s i z e e f f e c t s i n the r e l a t i o n s h i p between l a r v a l weight and exposure time.  8  18  Beach S t r a t i f i c a t i o n The beach survey done a t the time o f spawning ( F i g u r e 10) showed an i n c r e a s e i n egg weight with beach h e i g h t . was s i g n i f i c a n t  (p < . 0 1 ) .  This trend  By m i d - i n c u b a t i o n ( F i g u r e 11) the  r e l a t i o n s h i p had d i s a p p e a r e d , becoming convexly c u r v i l i n e a r w i t h no s i g n i f i c a n t d i f f e r e n c e s sequenced o b s e r v a t i o n s  between beach l e v e l s .  c o n s i s t i n g of an e a r l y (4 days) and a  (16 days - h a t c h i n g ) stage f o r a s i n g l e  late  to c l a r i f y  this  Time-  problem ( F i g u r e 1 2 ) .  egg mass was done  However, the  l6-day  sample was taken lower down on the beach and hatched en r o u t e to the l a b o r a t o r y .  The l a r v a l weights o b t a i n e d were assumed  to be a r e f l e c t i o n of t h e i r former egg weights and were compared with the k— day sample on a r e l a t i v e b a s i s .  No s i g n i f i c a n t  t r e n d s were i n d i c a t e d .  DISCUSSION  The spawners used i n t h i s all  r e c e n t l y mature h e r r i n g .  experiment were  As such, the r e s u l t s  essentially found a r e  o n l y t r u l y a p p l i c a b l e to the spawn of these young f i s h .  The  exposure time imposed on the spawn ranged up to 2/3 of a day, and reduced i n c u b a t i o n time,  i n c r e a s e d h a t c h i n g m o r t a l i t y , and  reduced l a r v a l l e n g t h and weight.  Possible  some of these p a t t e r n s a r e presented  explanations  for  below.  Incubation time dropped markedly when the eggs were first  exposed,  exposure t i m e .  but t h e r e a f t e r decreased g r a d u a l l y w i t h i n c r e a s e d The drop with o n l y two 2-hour exposure p e r i o d s  per day may be due to oxygen d e p r i v a t i o n .  In t h i s  regard,  19 0.24h  0.22 bD  -p  W  0.20  0)  bO bO W  0.18  MLT 1.0  0 Figure 10:  2.0 Beach Height (m.)  3.0  R e l a t i o n s h i p of egg s i z e to beach h e i g h t spawning, Bedwell Bay, A p r i l 2 0 , 1 9 7 0 .  at  0.24 r  0.22 b0  6  p bo  •H  0.20  M  CD bD bO  0.18  MLT 0 Figure 11:  1.0 Beach Height  2.0 (m.)  3-0  R e l a t i o n s h i p of egg s i z e to beach height at m i d i n c u b a t i o n (8 d a y s ) , Nanoose Bay, March 2 7 , 1 9 7 0 .  20  0.28  0.26  |  0.24  b0 w  0.22  (4 days)  0.20  0.14  0.12 ( 1 6 days) 0.10  MLT -1.0  F i g u r e 12  1.0  Beach Height (m.)  2.0  R e l a t i o n s h i p of egg s i z e to beach h e i g h t j u s t a f t e r spawning (4 days) and at h a t c h i n g ( 1 6 days) f o r the same egg mass. The l a t t e r i s f o r l a r v a e as the eggs hatched en route to the l a b . These samples taken at Icarus P o i n t , March 17 and 2 9 , 1 9 7 1 .  21 V o l o d i n (1956) n o t e d t h a t t h e r e was an e r r a t i c b u t t w o f o l d i n c r e a s e i n oxygen r e q u i r e m e n t s o v e r t h e i n c u b a t i o n p e r i o d . In a d d i t i o n , Rannak (1958) found t h a t h a t c h i n g was i n i t i a t e d when eggs were t r a n s f e r r e d t o l o w e r oxygen p r e s s u r e s .  Thus,  whereas oxygen needs were s a t i s f i e d i n a i r and water when t h e embryos began development,  j u s t p r i o r t o h a t c h i n g , when oxygen  demand was much h i g h e r , t h e eggs may have been i n c a p a b l e o f o b t a i n i n g adequate  s u p p l i e s from a i r .  A p o s s i b l e reason f o r  l o w e r oxygen a v a i l a b i l i t y i n a i r would be t h e impairment o f the  egg membrane by d e s i c c a t i o n , t h e r e b y r e s t r i c t i n g e n t r y .  As no l a r v a e h a t c h e d o u t d u r i n g t h e exposure p e r i o d s , i t might be t h a t a more f l a c c i d n a t u r e o f t h e membrane due t o d e s i c c a t i o n p r e v e n t e d i t s r u p t u r i n g u n t i l t h e eggs were once more submerged and t h e i r membranes t a u t by i n t e r n a l  pressure.  In t h i s study,  the beach s u r v e y eggs c o l l e c t e d a t 16 days were i n a d v e r t e n t l y made t o h a t c h en r o u t e t o t h e l a b o r a t o r y .  As c o n s i d e r a b l e  l i v i n g o r g a n i c m a t t e r was e n c l o s e d i n a v e r y s m a l l space, t h e oxygen was u n d o u b t e d l y d e p l e t e d i n a v e r y s h o r t t i m e , and hence, c o u l d have i n i t i a t e d h a t c h i n g o f t h e eggs. The o v e r a l l g r a d u a l d e c r e a s e i n i n c u b a t i o n time i s l i k e l y due t o t h e h i g h e r t e m p e r a t u r e encountered i n t h e a i r , promoting an i n c r e a s e d m e t a b o l i c r a t e . examined,  F o r t h e h i g h e s t degree o f exposure  t h e i n c u b a t i o n time r e a c h e d a minimum o f 17.8 days.  The r e d u c t i o n i n time a t t h i s beach l e v e l was r o u g h l y 7%, over 5$ o f w h i c h i s accounted f o r by the f i r s t exposure drop.  This  phenomenon p r o v i d e s a p o s s i b l e r e a s o n f o r d e p o s i t i o n o f spawn i n the  i n t e r t i d a l zone, which o b v i o u s l y must be o f some advantage  t o t h e s p e c i e s s u r v i v a l , and t h a t i s t o a t t u n e h a t c h i n g t o  22 i n c r e a s e d a i r and s u r f a c e water temperatures which are with p l a n k t o n p r o d u c t i o n , the source of l a r v a l  sustenance.  o t h e r words, as plankton p r o d u c t i o n i s dependent so a l s o i s I966),  associated In  on temperature,  i n c u b a t i o n time of h e r r i n g spawn ( B l a x t e r and Hempel,  and t h e i r c o i n c i d e n c e would n a t u r a l l y be b e n e f i c i a l  to  the emerging l a r v a e . 'Unfortunately, advantages.  exposure of spawn a l s o has s e v e r a l  dis-  Among these are the i n c r e a s e d h a t c h i n g m o r t a l i t y  and d e t r i m e n t a l e f f e c t s on l a r v a l l e n g t h and weight. The h a t c h i n g m o r t a l i t y on the spawning grounds was cons i d e r e d by T a y l o r  ( 1 9 6 4 ) to average 3 7 $ i f l o s s e s due to  p r e d a t i o n were not i n c l u d e d . inviability, desiccation.  T h i s may be a t t r i b u t e d  bird  to  overcrowding, and exposure to wave a c t i o n and The r e s u l t s  somewhat lower than t h i s the d u r a t i o n of exposure.  of t h i s  experiment show a m o r t a l i t y  (13 to 31%), and being dependent upon To some degree,  was not an experimental f e a t u r e  wave a c t i o n which  could account f o r the  difference.  What p a r t i n v i a b i l i t y of eggs played cannot be deduced i n study.  this  Eggs from small f i s h had a h i g h e r m o r t a l i t y than those  from l a r g e r spawners.  Toom ( 1 9 5 8 ) has demonstrated that  v i a b l e l a r v a e a r e produced by small f i s h ,  and hence,  less  one might  suspect t h a t they were i n c a p a b l e of s u r v i v i n g the r i g o r s of exposure o r completing h a t c h i n g m a n i p u l a t i o n s . The egg d e n s i t y  seems to have mixed e f f e c t s .  one hand l a r g e clumps might h i n d e r f e r t i l i z a t i o n , supplies, eggs.  On the limit  oxygen  and promote waste product accumulation of the i n t e r n a l  On the other hand, these same l a r g e r clumps would prevent  23 desiccation and mechanically protect (not applicable i n this experiment) the inner eggs.  It was found that the small egg  clumps did i n fact have a higher mortality than the larger ones. Undoubtedly though, as egg numbers get very large, the mortality w i l l increase many times and easily surpass that of the smaller clumps.  This has been shown by Runnstrom (19^1).  It would seem,  then, that an optimum number of eggs per clump must exist f o r maximum s u r v i v a l . conclusion.  McMynn and Hoar (1953) have also come to t h i s  It i s possible that optimum clump size w i l l depend  on the height up the beach at which the eggs are deposited. The survivors would be from some middle layer, deep enough to be protected, but not so buried as to be smothered — of t h i s layer depending on the degree of exposure.  the depth  Whether or  not clump size varies with f i s h size i s also not known. As f o r the effect of exposure on the individual egg, Hamdorf (1961), working on trout eggs, suggests that a higher mortality could stem from introducing embryos which are beyond hatching size to lower oxygen regimes.  In t h i s case, they  suffocate as the oxygen available i s no longer s u f f i c i e n t to cover t h e i r minimum needs, and the f l a c c i d exposure membrane prevents hatching.  Blaxter and Hempel (I96D have also noted  the possible mortality due to accumulation of waste when eggs are exposed. It seems probable that herring l a y t h e i r eggs as high on the beach as the t i d e at spawning time w i l l allow.  Referring to  Figure 1, t h i s would be at or near 4 meters above mean low tide, a place where exposure i s lengthy and mortality i s r e l a t i v e l y  24 high.  This d i s t r i b u t i o n i s  i n f a c t borne out by T a y l o r  and the beach samples taken i n t h i s t h a t an e x c e p t i o n a l l y  study.  (1964)  It might even occur  h i g h t i d e d u r i n g a spawning would r e s u l t  i n eggs being d e p o s i t e d  too h i g h on the beach and hence,  sub-  j e c t i n g them to a much more severe degree of m o r t a l i t y . c o u l d account f o r some p a r t of y e a r - c l a s s numbers.  fluctuation  This  in  On the other hand, l a y i n g eggs h i g h on the beach  has been shown ( T e s t e r , survival.  In t h i s  1942)  case,  to c o n t r i b u t e to  year-class  the eggs on the lower beach and i n  the water d i e d f o r some unknown r e a s o n , w h i l e the h i g h e r eggs survived. As a l r e a d y suggested, on l a r v a l c h a r a c t e r i s t i c s . , (7%) a t f i r s t  exposure  is  exposure a l s o has some e f f e c t s The i n i t i a l drop i n l a r v a l  expected,  as e a r l i e r h a t c h i n g would  c e r t a i n l y mean l e s s time f o r l a r v a l growth or the of y o l k i n t o body t i s s u e . additional  conversion  The l a c k of f u r t h e r decrease w i t h  exposure might w e l l be due to the i n c r e a s i n g mean  temperature enhancing the metabolic r a t e and hence, i n c u b a t i o n time d i f f e r e n c e s . may v e r i f y Hamdorf's ( I 9 6 I )  A l t e r n a t i v e l y , these  of exposure t i m e .  nullifying results  view t h a t l a r v a l l e n g t h i s  r e l a t e d to the p r e v a i l i n g oxygen p r e s s u r e and i s  directly  independent  To some degree e a r l i e r h a t c h i n g must a l s o  add to m o r t a l i t y d u r i n g the l a r v a l has s t a t e d ,  length  stage i f ,  as Rannak  exposure p r i o r to h a t c h i n g r e a d i n e s s  premature and t h e r e f o r e  less viable larvae.  This  (I958)  results  in  experiment  i n d i c a t e d that the s m a l l e r eggs y i e l d e d s h o r t e r l a r v a e .  It  might be that these l a r v a e are l e s s v i a b l e than those from  25 l a r g e r eggs.  This would further add to t h e i r disadvantages  r e l a t i v e to larger larvae which have lesser food requirements, faster swimming speed, and a greater degree of thermal insulat i o n (Marshall, 1953). Larval weight, on the other hand, (which includes yolk) might not be expected to change r e l a t i v e to exposure time.  In  f a c t , there i s no change except at the highest degree of exposure where a decrease i n weight begins.  If there were any importance  in the i n i t i a l increase i n weight with exposure, t h i s would lend support to Hamdorf's (1961) proposal that hatching weight may a c t u a l l y benefit from, exposure up to a point, possibly as a r e s u l t of increased yolk u t i l i z a t i o n e f f i c i e n c y .  In t h i s  experiment, the l a t t e r stage i s manifest i n a 12% decrease i n weight with the greatest exposure.  This drop may be due to i n -  e f f i c i e n c y of yolk conversion into body tissue.  It coincides  with s i m i l a r sharper trends i n both incubation time and hatching mortality, and suggests that a " c r i t i c a l point" i n exposure time i s reached above which the environment i s so harsh that the eggs stand l i t t l e chance of contributing to year-class strength.  This upper l i m i t would seem to be near 14 hours of  exposure per day, or roughly the 3-5 meter beach l e v e l during the spawning season.  Eggs deposited above t h i s l e v e l are not  only subjected to a higher mortality, but also produce smaller, l e s s viable larvae. From t h i s study one might i n f e r that most spawning i s high up on beaches, where the larger eggs from larger f i s h are better f i t t e d to survive.  In consequence, reduction i n the  26 s i z e of spawning f i s h i m p l i e s a lower average r a t e of s u r v i v a l . An optimum clump s i z e i s  f u r t h e r suggested, but i t s  to f i s h s i z e o r beach l e v e l  i s unknown.  (Rannak, 1 9 5 8 ) ,  l a r g e r f i s h spawn f i r s t  p e r i o d u s u a l l y l a s t s s e v e r a l days many t i d a l movements),  relationship  Though the o l d e r and s i n c e the  (and t h e r e f o r e  spawning twice  as  the eggs of a l l f i s h may be evenly  buted over the spawning zone.  distri-  The beach c o l l e c t i o n of eggs a t  spawning d i d however i n d i c a t e that the l a r g e r eggs were f u r t h e r up the beach.  U n f o r t u n a t e l y , the o t h e r beach surveys were f a r  less instructive,  and the t r e n d s are f u r t h e r complicated by the  i n c r e a s i n g m o r t a l i t y w i t h exposure and the d i f f e r e n t i a l m o r t a l i t y due to f i s h and clump s i z e s . possible  effects  Another source of c o n f u s i o n i s  the  of wave a c t i o n and p r e d a t i o n by b i r d s as noted  earlier. In any event, a heavy f i s h i n g i n t e n s i t y which kept individual of  the  f i s h s i z e small would imply a decreased average  s u r v i v a l at h i g h e r l e v e l s of spawning.  has a hidden dimension i n a l s o  Thus,  fishing  pressure  r e d u c i n g spawn s u r v i v a l .  LITERATURE CITED  Blaxter,  J.H.S.,  and G. Hempel  (I96D  " B i o l o g i s c h e Beobachtungen b e i der Aufzucht von Heringsbrut", H e l g o l a n d . Wiss. M e e r e s u n t e r s . , (Fish. Blaxter,  Res. Bd. Canada,  J.H.S.,  7 ( 5 ) : 260-283.  E n g l i s h t r a n s l a t i o n #708)  and G. Hempel ( 1 9 6 3 )  "The i n f l u e n c e of egg s i z e on h e r r i n g l a r v a e (Clupea harengus L . ) " , J.  Cons. E x p l .  Mer, 2 8 ( 2 ) : 211-2-4-0.  rate  27  Blaxter, J.H.S., and G. Hempel (1966) " U t i l i z a t i o n of yolk by herring larvae", J. Mar. B i o l . Assoc. U.K., 4 6 ( 2 ) : 219-234. Cushlng, D.H., and J.P. Bridger (1966) The Stock of Herring i n the North Sea and Changes Due to Fishing, Min. Agr. Fish. Fd., Fish. Invest., Series II, Vol. 2 5 ( 1 ) :  123  pp.,  London.  Hamdorf, K. (1961) "Die Beeinflussung der Embryonalund Larvalentwicklung der Regenbogenforelle (Salmo irldeus Gibb.) durch die Umweltfaktoren CVj-Partialdruck und Temperatur", Z e i t . Verg. Physio., 4 4 ( 5 ) : 523-549. Hempel, G., and J.H.S. Blaxter (I967) "Egg weight i n A t l a n t i c herring (Clupea harengus L.)", J. Cons. Expl. Mer, 3 1 ( 2 ) : 1 7 O - I 9 5 . Marshall, N.B. (1953) "Egg size i n A r c t i c , Antarctic, and deep-sea fishes", Evolution, 7 ( 4 ) : 328-341. McMynn, R.G., and W.S. Hoar (1953) "Effects of s a l i n i t y on the development of the P a c i f i c herring", Can. J. Zool., 31: 417-432. Nagasaki, F. (1958) "The fecundity of P a c i f i c herring (Clupea p a l l a s l i ) in B r i t i s h Columbia coastal waters", J. F i s h . Res. Bd. Canada, 15(3)' 313-330. Outram, D.N. (1955) The Development of the P a c i f i c Herring and Its Use in Estimating Age of Spawn, Fish. Res. Bd. Canada, Pac. B i o l . Stn., C i r c . #40. Rannak, L.A. (1958) — in Russian. ("Quantitative study of the B a l t i c herring eggs and larvae i n the northern part of the Gulf, of Riga and the p r i n c i p a l factors i n determining t h e i r survival"), Trudy VNIRO, 34:  7-18.  (Fish. Res. Bd. Canada, English t r a n s l a t i o n #238)  28 Runnstrom, S.  (19^1)  " Q u a n t i t a t i v e i n v e s t i g a t i o n s on h e r r i n g spawning and i t s y e a r l y f l u c t u a t i o n s at the west coast of Norway", Flskeridir. Taylor, F.H.C.  S k r . Havundrsok.,  6(7 )  :  71 PP«  (I963)  "The s t o c k - r e c r u i t m e n t Columbia h e r r i n g  relationship in British populations",  Rapp. C.P.I.E.M., 15^1 279-292. Taylor,  F.H.C.  (1964)  L i f e H i s t o r y and Present Status of B r i t i s h Columbia H e r r i n g Stocks. Fish. Tester,  Res. Bd. Canada, B u l l e t i n #143, 81 pp.  A . L . (1937)  "Populations of h e r r i n g (Clupea p a l l a s i i ) i n c o a s t a l waters of B r i t i s h Columbia", J. Tester,  F i s h . Res.  the  Bd. Canada, 3 ( 2 ) : 108-144.  A . L . (1942)  "A h i g h m o r t a l i t y Fish.  Res.  of h e r r i n g eggs",  Bd. Canada, Prog. Rep. P a c . ,  53* 16-19.  Toom, M.M. (1958) — i n R u s s i a n . ("Experiments eggs"),  i n the  incubation  of B a l t i c  herring  Trudy VNIRO, 34: 19-29( O f f i c e of Tech. S e r v . , U . S . Dept. of Commerce, Wash. 25, D . C . , USA, E n g l i s h t r a n s l a t i o n # 6 l l ) Volodin,  V . M . (1956) — i n R u s s i a n .  ("Embryonic development of the autumn B a l t i c h e r r i n g and t h e i r oxygen requirements d u r i n g the course of development"), Voprosy I k h t i o l o g l l , 7- 123-133( F i s h . Res. Bd. Canada, E n g l i s h t r a n s l a t i o n  #252)  29 APPENDICES  30 APPENDIX A - Apparatus Design  The tank, f i t t i n g s ,  and t u b i n g were a l l  polyethylene.  For each tank, the water i n f l o w d i v i d e d i n t o f o u r  separate  compartments of ten i n c u b a t o r s e n t e r i n g at the bottom r e a r ( F i g u r e 1A).  During the exposure p e r i o d i t  flowed a c r o s s  the  f l o o r under the i n c u b a t o r s and out the bottom f r o n t c o n t r o l drain,  e x i t i n g through the e l e c t r i c a l v a l v e .  T h i s v a l v e was  open o n l y when:., energized and operated on a time c l o c k .  During  submergence the v a l v e was c l o s e d and the water f i l l e d the tank, f l o w i n g out the top f r o n t overflow.  Emptying o r f i l l i n g  the  tank took J or k minutes. The i n c u b a t o r s ( F i g u r e 2A) were made from 3 mm. p l e x i g l a s s t u b i n g (2.5 cm. i n s i d e diameter) open a t the t o p . bottom and the f o u r m i d - l e v e l s i d e p o r t s  The  (1.25 cm. diameter)  were covered with N i t e x #253 monofilament n y l o n s c r e e n . lower 1.25 cm. separated from the top which i t tight  f r i c t i o n - g r i p band.  The  secured w i t h a  The reason f o r t h i s was to  easy s t r i p p i n g of the eggs onto the bottom s c r e e n .  allow  T h i s whole  u n i t was bonded t o g e t h e r u s i n g ethylene d i c h l o r i d e . Each tank compartment was d i v i d e d i n h a l f h o r i z o n t a l l y by a p l e x i g l a s s  plate  (secured by S i l i c o n e S e a l a n t )  which ten h o l e s had been d r i l l e d .  The i n c u b a t o r s  through fitted  through these h o l e s and l o c k e d i n by bayonet mount so changing water l e v e l d i d not d i s l o d g e  them.  the  The water was  made to flow up through the eggs and out the s i d e p o r t s when submerged, never r e a c h i n g the top of the tube.  Due to  their  31 demersal and adhesive n a t u r e ,  the eggs themselves remained  a t t a c h e d to the bottom screen and d i d not f l o a t  f r e e l y i n the  upper tube. The apparatus was run c o n t i n u o u s l y f o r two weeks p r i o r to the experiment - f o r adjustment of the environmental c o n d i t i o n s and the removal of p o s s i b l e affect  the  eggs.  l e a c h i n g m a t e r i a l which might  F i g u r e 2A:  C r o s s - s e c t i o n of i n c u b a t o r i n tank.  33 APPENDIX B - Raw Data  The data f o r the spawners  (Table IA) i s  listed  a c c o r d i n g to the f i s h number, the o r d e r i n which they were used.  Numbers 14,  30 to 34, and 39 were e l i m i n a t e d due to  100$ m o r t a l i t y i n a l l i n c u b a t o r s . #14  d i e d i s not known.  Why the eggs from spawner  On examination they formed a hard  mass w i t h no s i g n of embryonic development.  It  is  possible  they may have been i n f e r t i l e or were i n the process reabsorbed when s t r i p p e d .  The l a t t e r  is  of  being  s a i d to happen when  spawners a r e kept f o r l o n g p e r i o d s i n h o l d i n g t a n k s .  The  o t h e r s i x f i s h were from the t r a w l caught b a t c h , and a l l eggs d i s i n t e g r a t e d . eggs,  So as not to a f f e c t  the o t h e r  the  healthy  these i n c u b a t o r s were a l l removed halfway through the  incubation period. was l e f t  for  Data f o r a t o t a l  of 33 female  spawners  analysis.  Table IIA l i s t s the i n d i v i d u a l i n c u b a t o r data by exposure index.  The Incubator number consists of the f i s h number  f o l l o w e d by the exposure the spawners.  index and has the same order as  The zeros mean that t h e r e was no data and  were used as computer s e n t i n e l s o n l y .  T h i s l a c k of data  is  based on the f o l l o w i n g c r i t e r i a : (a)  Incubation time - i f l e s s than 20 eggs hatched,  the d i s t r i b u t i o n seemed too d i s p e r s e Pour values were r e j e c t e d on t h i s (b)  to p i n p o i n t 50$ h a t c h .  basis.  H a t c h i n g m o r t a l i t y - any i n c u b a t o r with an egg  number l e s s than 45 was c o n s i d e r e d inadequate f o r comparison  3k with means based on more eggs.  This l e v e l i s approximately  the lower boundary of the 95$ range of egg number and eliminated only one (c)  value.  Larval length - the mean number of larvae  measured per incubator was  3k; standard deviation * 15-  This  number was much l e s s than that for l a r v a l weight as many larvae were too bent or otherwise misshapen to measure accurately.  If  there were less than 10 measurable larvae, which again i s near the lower 95$ range boundary, then the data was not used. It was  thought that, since each incubator had a range i n  l a r v a l lengths, l e s s than 10 had too great a chance of not t r u l y representing the mean.  In t h i s case, 11 values were d i s -  carded, the lower numbers being due to few straight larvae or a high hatching mortality. per incubator was (d) cal balance was  limited to  The maximum number measured 100.  Larval weight - the s e n s i t i v i t y of the e l e c t r i the deciding factor here.  than 15 larvae was  determined inadequate to y i e l d a f a i r  estimate of the mean. fewer numbers may  Thus, anything less  Similar to l a r v a l length, however,  not have been representative.  mean number used was 6 l : standard deviation - Ik.  The actual Here also  the maximum number used from each incubator was 100 larvae. Hatching mortality again played a part i n t h i s elimination which involved 11 (e)  values.  Definite e r r a t i c values - there were only  two  rejections of t h i s nature, and both were f o r l a r v a l weight. These must have been handling mistakes as the weights were  f a r removed from the rest of the l a r v a l weight determinations. In fact, they were actually i n excess of the egg weights noted for their respective spawners.  TABLE  FISH NUMBER  X  2 3 4 5 6  8 9 10 11 12 13 15 16 17 18 19 2U 21 22 23 24 25 Zb  27 28 29 35 36 3 / 38 40  IA.  SPAWNER  LENGTH (MM.)  202. 218. 222. 205. 194. 214. 220. 205. 204. 218. 217. 213. 2U1. 193. 234. 192. 231. 205. 232. 217. 213. 203. 201. 219. 2U /. 216. 221. 213.' 200* 215. 20 /. 197. 215.  DATA  36  LIST  WEIGHT ( GM. )  86. 105. 102. 84. 72. 92. 110. 81. 83. 98. 110. 97. 79. 67. 134. 67. 127. 85. 128 • 110. 103. 76. 79. 107. 8/ • 97. 100. 86 • 74. 88.  //.  76. 98.  AGE EGG WEIGHT ( YR. ) (MG. )  3. 3c 3. 3. 3. 3. 4o 3. 3. 3. 3. 3. 3. 3. 5. 3. 4. 3. 5. 4. 3. 3. 3. 3.  ii.  4. 4. 3. 3. 4. 3. 3. 4.  0.2228 0.2884 0.2564 0.2182 0.2564 0.2526 0.2806 0.2682 0.2668 0.2554 0. 2474 0.2776 0.2872 0.2748 0« 2876 0.2478 0.3204 0.2640 0. 29 /0 0.2636 0.2558 0.2926 O i 2738 0.3204 0.2 726 0.3196 0.2966 0.2752 0.2658 0.3068 0.2 /58 0.2380 0.2212  TABLE  I I A.  INCUBATOR DATA  37  LIST  (ZERO VALUES MEAN NO DATA = COMPUTER  CONTROL  SENTINEL  ONLY)  DATA  INCUBATOR NUMBER  INCUBATION TIME (DAYS)  HATCHING MORTALITY (PER CENT)  LARVAL LENGTH (MM.)  LARVAL WEIGHT (MG.)  NUMBER OF EGGS  10 20 30 40 50 60 70 80 90 100 110  1 9 .. 15 1 9 *• 1 8 1 8 ..82 1 9 .>Q5 1 9 ..76 1 9 ..07 1 9 ..36 19 • 22 1 8 .. 7 1 1 9 .i 0 4 18 • 7 0 IB • 6 2 1 8 ..95 1 9 .. 1 9 2 0 ..15 1 9 ..05 1 8 ..48 1 9 ..12 1 8 .. 9 1 1 9 .32 18 .66 19 .59 1 8 .. 7 5 18 .64 18 i 7 6 18 .79 19 .72 19 .91 19 .50 1 9 .5 3 19 .83 19 .50 19 » 15  1 3 ..3 1 2 .1 1 3..6 5. 9 1 4 ..5 12. 3 1 7 ..4 19. 0 1..8 1 6 .»1 3 .. 2 1 9 .. 3 1 6 ..2 4 2 ..4 2 3 ..7 2 6 .,0 1 3 ..6 0.. / 3..6 6..5 1 0 .. 3 1 3 ..4 6..5 3 .6 4 .3 6 .3  7,.3 1  0.000 0. 0 0 0 0.066 0.056 0.068 0.050 0.084 0.083 0.066 0.117 0.076 0.081 0.085 0*092 0.087 0.074 0. 1 0 5 0.082 0.098 0.099 0.093 0. 1 0 9 0.102 0. 1 2 3 0. 1 0 6 0.121 0.113 0.108 0.114 0.12/ 0. 1 2 0 0.088 0.072  255 . 132* 166. 102. 166 e 65 . 92. 79. 112. 56. 216.  12U 130 150 160 170 180 190 200 2 10 220 230 24 0 260 270 280 290 350 36U 370 380 400  7 .2 7 .3  1 7 .4 IV . 2 2 1..7 2 6 ..9 1 4 ..6  7..20 7. 4 4 7..36 7..17 6..91 7..22 7.. 3 5 7«.11  6.. 8 9 7.. 1 5 (i. 1 9 7..30 7..38 7..7 5 6. 8 0 7..98 / .B5 7. 9 0 8..40 7.. 8 5 8..2 1 7. 9 9  8 .49 8 .33 8..2 2 8.. 1 5 8 .27 8 .28 8 .8 2 8 .19 8..28 7,. 9 6  ii?U .  136. 118 . 156. 104. 81. 142 . 138 . 107. 126. 97. 155. 111. 185. 144. 166. 193. 121. .  ftit  106. 167. 89 .  TABLE  I IA  38  (CONTINUED)  2  INCUBATOR NUMBER  12 22 32 42 52 62 72 82 92 102 112 122 132 152 162 172 182 192 202 212 222 232 242 252 262 272 282 292 352 362 372 382 402  INCUBATION TIME (DAYS)  18. .00 1 8 i .30 18. . 2 5 1 8 . .33 1 8 . .33 18. .29 18. . 2 8 18. . 3 8 18. . 0 4 18. . 13 18. . 14 18. . 3 4 18. .06 0. .00 18. .20 18. . 10 17. .61 18. .00 18. .86 18. . 0 4 17. .99 18. .26 18. . 0 8 17. .46 17 .57 17 . 8 5 17. . 7 4 18 .53 18. . 2 5 18 .50 18 .51 18. . 5 7 18 . 4 7  HOUR  DATA  HATCHING MORTALITY I PER C E N T )  LARVAL LENGTH (MM.)  2 9 . .2 19. . 1 1 8 . .2 5 <1 26. 7 3 <.1 2 0 . .5 18. .3 4i 0 8« 5 1. .8 3 6 . .4 4 4 . .3 76. > 1 3 1 . .9 21. 0 3. ,7 4. .8 8..3 7..5 2. 7 13. 7 13. 9 18. .3 1. . 4 10. .1 0. .6 5. 9 10. .4 5 4 . .5 16. .8 15. .4 34. .3  7<.07 It 07 6< 89 6« 92 6. . 6 4 6. 96 It 06 6..79 6.. 8 7 6.. 7 4 6« 89 6.. 5 1 6.. 4 5 0<.00 6..50 6<. 3 3 6. 90 6.. 6 8 7..93 6.. 6 9 6..82 7.. 1 1 6..72 7..5 1 7.. 9 8 7.. 9 2 8<.00 8 .06 8.. 0 7 8.. 0 3 8 .09 7,. 89 8 .14  LARVAL WEIGHT (MG.)  0 . 054 0* 104 0.076 0.089 0.090 0.080 0 . 100 0.080 0.070 0 . 107 0.103 0.081 0.083 0.000 0.090 0.079 0.098 0.084 0.120 0.097 0.085 0 . 102 0.098 0.122 0.131 0.151 0.109 0.101 0.114 0.131 0.120 0.086 0.067  NUMBER OF EGGS  250. 157. 137« 156. 131. 98. 127. 131. 101. 142. 170. 154. 79. 46. 94. 143. 81. 147. 156. 93. 110. 95. 101. 131 e 145. 148 . 168. 271. 173. 101. 113. 247. 67.  TABLE  39  I IA (CONTINUED)  4 HOUR DATA  INCUBATOR NUMBER  INCUBATION TIME (DAYS)  HATCHING MORTALITY (PER CENT)  LARVAL LENGTH (MM.)  LARVAL WEIGHT (MG.)  NUMBER OF EGGS  14 24 34 44 54 ~6Tf 74 84 94 104 114 T7^+ 134 154 164 174 184 T74" 204 214 224 234 244 "254 264 274 284 294 354 "36~4 374 384 404  18.19 18.67 18.10 18.15 18.30 18.08 18.28 18.05 17.65 18.09 18.35 18.30 0.00 18.33 18.61 18.37 18.23 18.21 0.00 17.97 17.58 18.45 18.03 17.88 17.41 17.69 17.98 18.70 16.79 18.48 17.63 16.43 18.44  10.0 18.5 8.9 16.5 45.7 9~T7 31.0 11.8 10.3 20.4 7.9 T3T5 80.8 46.8 32.8 33.1 20.1 Zf77i 0.0 42.7 6.1 22.1 17.7 T5T3 2.0 3.3 17.0 2.6 30.1 34T5 21.1 7.3 42.3  6.96 6.71 6.82 6.91 6.79 /.20 7.13 7.37 7.24 6.90 6.75 7T1J+ 0.00 7.19 7.16 6.76 7.34 7TCT5 0.00 6.82 7.07 7.22 6.92 679~9 6.82 6.92 7.58 7.82 7.53 0T0~Q~ 7.76 8.00 0.00  0.077 0.112 0.084 0.083 0.075 0.0 /4 0.108 0.076 0.067 0.120 0.091 U. 130 0.000 0.076 0.107 0.086 . 0.131 0.089 0.000 0.090 0.091 0.101 0.098 0.114 0.100 0.111 0.144 0.112 0.112 0.000 0.123 0.091 0.000  201. 135. 157. 164. 70. TU3T 113. 127. 97. 142. 140. 125 . 78. 111. 122. 136. 144. HT3T 35. 82. 131. 122. 96. TW7 152. 152. 176. 190. 173. 7~8T 90. 151. 71.  40 TABLE  I IA  (CONTINUED)  6  INCUBATOR NUMBER  INCUBATION TIME (DAYS)  HOUR  DATA  HATCHING  LARVAL  LARVAL  MORTALITY  LENGTH  WEIGHT  (MM.)  (MG.)  EGGS  (PER  CENT)  NUMBER OF  16  1 7 .. 9 3  3 5 ..7  6. 9 4  0.063  140.  26 36 -+6  18 . 4 4 17 . 9 6 18 . 2 7  3. 0 1 4 ..5 1 2 ..5  7 .. 0 2 6<. 7 5 6 .. 5 4  0.106 0.069 0.076  199 . 131. 128.  56 66 76  18 . 2 1 18 . 3 1 18 118  6 .. 3 5 6 .. 6 6 6 .. 7 4  0.112 0.082 0.090  85. 129. 116.  86 96 106 116 126 136 156 166 176  18 . 0 2 1 8 .. 0 6 1 8 .. 2 4 1 8 .. 6 6 18 . 3 6 1 8 .. 0 2 18 . 2 5 1 8 .. 7 9 18 . 4 8  40. 0 1 0 ..9 1 1 ..2 16. 9  186 196 206  1 7 .. 9 8 1 7 .. 9 6 1 8 .. 5 2  11.. 1 1 4 ..4 34< 7 20. 2 7 4 ..2 73. 0 39. 8 10i.2 8. 8 6 ..6 24. 7  216 226 236 246 256 266  1 8 .. 3 9 1 6 .. 7 6 1 8 .. 6 1 1 8 .. 5 4 1 7 .. 8 2 1 7 .. 6 9  40. 0 10. 9 3 7 ..3 20. 0 6 ..3 2 .. 4  7 .. 4 3 7 .. 3 3 7. 87  276  1 7 .. 6 6 1 7 .. 9 2 17 • 8 1 17 . 6 9 18 • 6 3  1 ..3 13. 9 2 .. 4 1 3 .. 1 5 3 .. 1  17 • 6 4 16 • 76 17 • 6 4  286 29 6 356 366 376 386 40 6  0.076  148 .  0 0 0 0 0 0 0 0  .088 .127 .073 .090 .000 .000 . 102 .070  117. 97. 118 a 130. 89 .  0.124 0.089 0. 104  80 . 152. 170 .  7 .. 5 7 7. 89 7. 79  0 . 106 0.088 0.118 0.114 0.121 0 . 10 7  130. 17 5 . 150. 180 .  7« 8 7  0.125  152.  2 6 ..8  8. 05 8 .. 1 0 8 .. 0 7 0<. 0 0 8 .. 0 8  0. 0. 0. 0. 0.  187. 167. 145 . 8 1 .  25« 9 4 9 ..5  7 .. 6 0 7 .48  0.087 0.077  6. 87 6< 4 0 7 .. 1 2 6 .. 4 9 6. 6 4 Oi 0 0 0 .. 0 0 7« 0 6 6 .. 5 2 7«. 3 4 6 .. 9 1 7. 0 1  146 110 113 108 117  111. 12 3 . 157.  159 . 167.  112. 135. 107.  4l TABLE  I IA  (CONTINUED)  8 HOUR DATA  INCUBATOR NUMBER  INCUBATION TIME (DAYS)  HATCHING MORTALITY (PER CENT)  18 28 38 48 58 68 78 88 98 108 118 i2b 138 158 168 178 188 198 20 8 218 228 238 248 258 268 278 288 298 358  16..86 17..36 17,.51 17..92 17..58 171.68 17..53 17..66 17..54 18 .36 17..63 1 /.52 17..37 18..49 17..60 17 .62 17 .65 17 .58 . 17..57 0 .00 18..27 18 .38 18 .30 1 /.68 17 .70 17 .68 17 .80 17 .88 18 .59 18 • SU 18 • 50 0 • 00 17 .67  10..3 24..4 58..6 15..6 .4 4 3. 31..6 3..6 18..7 3..4 9..6 29..9 30. U 70..8 25..0 35..6 .2 42 < 28<.8  378 388 40 8  3i . V  .5 36 . 73..7 14..2 14 .3 16..7 2 1> 1 1 .8 26 .3 26..0 20 .4 1 1.6 6 7. .y 48..9 94 .9 39 .8  LARVAL LENGTH (MM.)  LARVAL WEIGHT (MG.)  NUMBER OF EGGS  7. 95 7..48 7. 9 1 6. 27 6..71 fi 02 6c 66 6..63 6« 77 6..77 6..45 6..16 0<.00 6< 86 6..91 6. 81 6..93 b i .84 6..95 0, 00 6,.76 7..16 7..0 1 1.63 l i .49 l i ,47 7 ,66 7<,60 7.,14 b<>uy 8.,04 0.,00 7 .38  0.. 046 0., 106 0,.055 0. 060 0..000 0..000 0<.055 0. 075 0..045 0,.110 0<,055 O i ,05 / 0.,000 0<.070 0.,065 0..044 O i , 102  117. 205. 70 . 135. 99. 57. 111. 123* 119. 230. 177.  U I>UtiU Oi  ,072  OI ,000 Oi  ,110  OI ,090  0 ,114 0 » 136 0<» 102 0 . 133 0 .113 0 .112 0 .115 0 . 120 0 . 120 0<,000 0 .090  iUU *  89. 52. 101. 83. 118 . iy 2 . 178. 57. 141. 98 » H4o 152 . 226. 167. 192. 211. 138 . 112. 92 • 158. 113.  42 APPENDIX C - Spawner C o r r e l a t i o n s  A comparison of the v a r i o u s experimental characteristics  l e d to the f o l l o w i n g  spawner  observations:  s i z e was found to be weakly c o r r e l a t e d to f i s h  length  ( F i g u r e 3 A ) , f i s h weight ( F i g u r e 4A), and to f i s h ( F i g u r e 5A).  On the other hand, f i s h l e n g t h  and f i s h weight f i s h age,  age  ( F i g u r e 6k)  ( F i g u r e ?A) were more s t r o n g l y r e l a t e d  to  and the r e l a t i o n s h i p of f i s h l e n g t h to f i s h weight  ( F i g u r e 8A) was very h i g h l y  correlated.  From t h i s i n f o r m a t i o n , and f i s h  The egg  i t was decided that  egg  l e n g t h would be used as bases f o r a n a l y z i n g  incubator data.  the  The use of both f i s h weight and l e n g t h would  have been redundant due to t h e i r high a s s o c i a t i o n . was s e l e c t e d as these measurements involved possible  size  Length  were more exact; weight  v a r i a t i o n i n moisture  content and v e s t i g e s  o f gonads (which were removed f o r t h i s d e t e r m i n a t i o n i n d e t e r m i n a b l e amounts of eggs were a l r e a d y m i s s i n g ) .  since The  use of age was r e j e c t e d because of the v e r y narrow and skewed d i s t r i b u t i o n of v a l u e s .  In a d d i t i o n , due to the poor  c o r r e l a t i o n of f i s h l e n g t h and egg s i z e , to use both these approaches to the  data.  it  seemed necessary  43 o  0.32  ©  o  0.30  g >  •P  0.28  «> 0.26 H-i  0) bO  $ 0.24 0.22  190  '  200  '  210  '  Spawner Length F i g u r e 3A»  220  '  240  230  (mm.)  R e l a t i o n s h i p of egg s i z e to spawner  0.32  length.  ©  0.30 !? 0.28 p §0.26 <D .3  bO  $0.24  0.22  _ / /  1  ^ 6 0  1  1  80  1  1  Spawner Weight Figure 4 A :  1  100  1  1—  120  (gm.)  R e l a t i o n s h i p of egg s i z e to spawner weight w i t h gonads removed.  140  44  3  0.32  0.30  g> 0.28 -p  «> 0.26  'H  <D  bO M  0.24 0.22  o o  Spawner Age F i g u r e 5A:  (yr.)  R e l a t i o n s h i p of egg s i z e to spawner  age.  240 r  Spawner Age ( y r . ) F i g u r e 6As  R e l a t i o n s h i p of spawner l e n g t h to  age.  140  Spawner Age ( y r . ) Figure 7 A :  R e l a t i o n s h i p o f spawner weight w i t h gonads removed to age.  46  APPENDIX D - Computations Summary  These tables summarize the means and standard deviations of a l l the analyses made i n t h i s study.  For the  experimental work, there i s a separate table f o r each of the characteristics  examined, thus incubation time may be found i n  Table IIIA, hatching mortality i n Table IVA, and l a r v a l length and weight i n Tables VA and VIA respectively.  The layout i s by  exposure index f o r the t o t a l data and f o r the groupings of egg size, f i s h length, and clump size.  The number of data re-  presented by each mean i s dependent upon the c r i t e r i a l a i d out in Appendix B. and 11  Maximally, i t should be 33 for the t o t a l data  each f o r the groupings.  In fact, i t i s found that a  minimum of 28 f o r t o t a l s and 7 f o r groups exists, but with most data being close to the maximum l e v e l . The egg weights f o r the beach s t r a t i f i c a t i o n surveys (Table VIIA) are arranged by beach l e v e l and the c o l l e c t i o n time r e l a t i v e to the incubation stage of the spawn.  The  height above mean low tide that the sample was taken i s also shown.  The means are based on 10 subsamples per beach l e v e l  throughout.  It should also be pointed out that the weights  f o r the c o l l e c t i o n done at 16 days are f o r larvae because the eggs hatched on the way to the laboratory f o r preservation, and thus can be compared to the other collections on a r e l a t i v e basis only.  Table IIIA:  Computations f o r i n c u b a t i o n time (days).  Exposure Characteristic  0  time twice per day  (hr. )  4  2  8  6  19.16 * 0.42  18.1? + 0.31  18.05 + 0.50  18.07  + 0.47  17.81 + 0.41  Small  19.09 + 0.32  18.24 + 0.19  18.01  17.93 + 0.64  17.71 + 0.42  Medium  19.18 + 0.44  18.17  Large  19.21 + 0.51  18.10 + 0.41  Small  19.22 + 0.34  18.21  Medium  19.14  Large  19.12 + 0.50  18.09  Small  19.22  O.36  18.15 + 0.26  18.10  + 0.32  18.14 + 0.33  17-82  0.44  Medium  19.00 + 0.29  18.09 + 0.33  18.27  + 0.30  18.10 + 0.55  17.86  0.51  Large  19.26 + O.56  18.26 + 0.33  17-78 + O.67  17.96 + 0.53  17.72 + 0.26  (1) T o t a l data (2) Egg s i z e  0.29  0.57  17.92 + 0.52  18.04  + 0.31  17.98 + 0.44  0.34  18.23  + 0.38  17.74  18.25  0.37  (3) F i s h l e n g t h +  0.45  + 0.18  17.86 + 0.70  18. 05 + 0.51  17.84 + 0.57  18.22 + 0.32  18. 06 + 0.42  17.88 + 0.51  17.90 + O.36  + 0.38  18.22 + 0.27  18.26  + O.32  17.67 + 0.27  (4) Clump s i z e  Table IVAs  Computations f o r h a t c h i n g m o r t a l i t y ( $ ) . Exposure time twice p e r day ( h r . )  Characteristic  0  2  4  6  8  13.0 +  8.9  17..8 + 16.8  21.5 ± 17.1  23.3 + 19.2  31.2 ± 22.0  Small  13-3 +  7.9  15.1 + 11.7  18.9 + 14.7  23.6 + 14.2  35.5 + 25.3  Medium  13.4 + 12.3  17.8 + 21.7  18.5 ± 15.^  21.3 + 20.4  25.8 + 20.9  Large  12.4 +  20.5  27.5 ± 20.9  24.9 + 23.6  32.3 + 20.5  (1) T o t a l data (2) Eftfi s i z e  6.6  I6.9  (3) F i s h l e n g t h  (4)  Small  17.9 + 10.9  24.8 + 20.2  28.7 ± 22.2  32.7 ± 22.8  31-9 ± 28.6  Medium  11.1 +  6.9  15.9 + 17.8  14.2 ± 13.6  17.9 + 18.3  30.0 ± 18.1  Large  10.1 +  7.0  12.6 +  9.7  21.5 + 11.0  19.2 + 13.^  31.6 ± 20. 0  Small  I6.3 +  5.3  26.1 + 24.3  35.2 + 21.6  36.1 + 24.2  43.1 + 18.7  Medium  11. 0 ± 11.8  14.3 +  19.8  9-5  24.4 + 11.7  21.0 + 18.8  Large  11.8 ±  12.9 + 11.3  10.7 ±  8.5  Clump s i z e  8.4  8.5  9.2 +  7.7  29.5  23.9  Table VA:  Computations f o r l a r v a l  length  (mm.).  Exposure time twice per day  (hr.)  Characteristic  0  2  6  4  8  0.55  7.19 + 0.60  7.13 + 0.34  7.22 ± 0.57  7.12 ± 0.52  Small  7-37 + 0.48  7.03 + 0.53  7.02 + 0.37  6.89  0.43  7.00 + 0.57  Medium  7.85 + 0.50  7.25 + 0.70  7.24 + 0.35  7.39 + 0.64  7.05  0.54  Large  7-93 + 0.53  7.32 + 0.60  7.13 + 0.27  7.43 + 0.49  7.29  0.44  Small  7-56 + 0.53  6.99 + 0.57  7.20 + O.38  7.13 + 0.66  7.00  0.40  Medium  7.90 + O.56  7.46 + 0.67  7.19 + O.36  7.34  0.62  7.19  0.64  Large  7.69 + 0.54  7.11 + 0.50  7.02 + 0.28  7.17 + 0.48  7.13 + 0.49  Small  7.61 ± 0.66  7.04 + 0.59  7.13 + 0.33  7.00 + 0.61  7. 06  Medium  7.82 + 0.50  7.05 + 0.57  7.05 + 0.24  7.13  0.53  7.05 + 0.56  Large  7.73 + 0.49  7.48 + 0.59  7.22 + 0.43  7.46  0.53  7.23  (1) T o t a l data  7.72  (2) Egg s i z e  (3) F i s h  length  (4) Clump s i z e  0.59 0.44  Table VTAi  Computations f o r l a r v a l weight Exposure time twice per day  (mg.).  (hr.)  Characteristic  0  2  4  6  8  o. 092 + 0.020  O.O96 + 0.020  0.099 + 0.019  0.099 ± 0.020  0.087 + 0. 028  Small  0.075 + 0.019  0.083 + 0. 014 0.087 + 0.013  0.083 + 0.019  0.071 + 0.027  Medium  0.095  + 0.016  0.097  0.100 + 0.014  0.088 + 0.026  Large  0.105 ± 0.016  0.109  0.019  0.115 + 0.014  0.114  Small  0.088 -± 0.016  0.085 + 0.016  0.085 + 0.014  0.093 + 0. 021 0.074 + 0.029  Medium  0.092 ± 0.026  0.101  0.101 ± 0. 018 0.097 ± 0.016  Large  O.O96 ± 0.018  0.102 ± 0. 012 0.110 ± 0.018  0.106 ± 0.023  Small  0.090 + 0.026  0.091 + 0. 018 0.086 + 0.019  0.101 + 0. 020 0.071 + 0.025  Medium  0.097 + 0.018  0.097 + 0.019  0.089  Large  0. 089  (1) T o t a l data (2) Egg s i z e  + 0.019  0.097  0.020  0.015  0.099 + 0. 028  (3) F i s h l e n g t h ±  0.027  0.098 ± 0.025 0. 086± 0.029  (4) Clump s i z e  + 0.016  0.104  0.017  0.101 + 0. 024 0.101 + 0.019  0.018  0.084  0.029  0.107 + 0.020  0.101  0.025  Table VIIA:  Computations f o r beach s t r a t i f i c a t i o n of egg weight (mg.), showing beach height (m.). Sample r e g i o n  Time and p l a c e of sample  Bottom  Low  Middle  High  Top  0.170 0.12  0.205 0.013 0.92  0.209 0. 014 1.71  0.227 0.007 2.53  0.232 0.010 3.33  0.239 0.015 0.21  0.237 0.012 0.70  0.016 1.16  0.240 0.012  0.220 0. 011 1.68  0.205 0.007  0.200 0.009  0.203  0.46  0.200 0.009 1.16  1.86  0.210 0.0072.56  0.130 0.005 -0.03  0.117 0.003 0.27  0.125 0. 002 0.58  (1) Spawning Bedwell Bay, 20/4/70. Mean Std. Dev. Height  0.004  (2) Post-spawning (4 days) Icarus Pt., 17/3/71. Mean Std. Dev. Height  0.248  1.37  (3) Mid-incubation (8 days) Nanoose Bay, 27/3/70. Mean Std. Dev. Height  -0.24  0.011  (4) Hatching (16 days) (larvae) Icarus Pt., 29/3/71. Mean Std. Dev. Height  0.127 0.005 -0.37  0.126 0. 004  1.04  52 APPENDIX E - S t a t i s t i c a l Analyses  The o r i g i n a l number of spawners was  a r b i t r a r i l y set at  f o r t y (with f i v e exposure periods) so that, with possible rejections, a good range of differences i n egg and f i s h sizes could be obtained.  One-way analyses of variance were used on  the data, and the following symbols have been employed to indicate the r e s u l t s : (—)  Due  not s i g n i f i c a n t  ( 0 )  s i g n i f i c a n t at p = .05 -  .10  ( * )  s i g n i f i c a n t at p = .01  .05  (**)  s i g n i f i c a n t at p <  -  .01  to unequal r e p l i c a t e numbers, Scheffe's method was  used to make a l l possible comparisons within the experimental exposure period data.  The  significance of differences within  the t o t a l data i s shown f o r each c h a r a c t e r i s t i c examined i n Table VIIIA. not tabulated.  The significance within the Individual groups was The between groups' s i g n i f i c a n c e of differences  are found i n Table IXA f o r a l l c h a r a c t e r i s t i c s . Table XA shows the significance of i n t e r a c t i o n among egg size, f i s h length, and clump size. exposure time was computer program.  In these l a t t e r two tables each  examined separately using Dr. N. Gilbert's Analyses of covariance were inadvisable  to unequal sample sizes. used a r c s i n transformation  A l l tests done on hatching  mortality  of the percentage data.  The significance of differences between beach l e v e l s f o r the s t r a t i f i c a t i o n surveys are found i n Table Scheffe's method was  also used here.  due  XIA.  Table VIIIA:  Significance  of d i f f e r e n c e s w i t h i n the t o t a l  Exposure p e r i o d  data.  comparisons  Characteristic 0-2 (a)  Incubation  2-4  4-6  6-8  time  0-4 •M--K-  2-6  4-8  —  —  (b) Hatching m o r t a l i t y ^ (c)  Larval  0-6  2-8  0  length  •H--H-  (d) L a r v a l weight  Used a r c s i n  transformation.  —  —  0-8  54  Table IXA:  S i g n i f i c a n c e of d i f f e r e n c e s  Characteristic  (a)  Exposure time twice per day (hr.)  0  I n c u b a t i o n time (1) Egg s i z e (2) F i s h l e n g t h (3) Clump s i z e  (b) Hatching m o r t a l i t y (1) Egg s i z e (2) F i s h l e n g t h (3) Clump s i z e (c) L a r v a l 1ength (1) Egg s i z e (2) F i s h l e n g t h (3) Clump s i z e (d) L a r v a l  between groups .  0  2  4  6  —  0  —  —  0  G  0  0  weight  (1) Egg s i z e (2) F i s h l e n g t h (3) Clump s i z e  **  Used D r . N. G i l b e r t ' s program. Used a r c s i n t r a n s f o r m a t i o n .  0  * 0  8  --  55  Table XA: S i g n i f i c a n c e of I n t e r a c t i o n - . 1  Exposure time twice per day ( h r . )  Characteristic  0 (a)  Incubation time (1) Egg s i z e / f i s h l e n g t h (2) P i s h l e n g t h / c l u m p s i z e (3) Egg s i z e / c l u m p s i z e  2  0  (b) H a t c h i n g m o r t a l i t y ^ (1) Egg s i z e / f i s h l e n g t h (2) F i s h l e n g t h / c l u m p s i z e (3) Egg s i z e / c l u m p s i z e  —  Used D r . N . G i l b e r t ' s program. Used a r c s i n t r a n s f o r m a t i o n .  0  —  *  1 2  8  0  (c) L a r v a l l e n g t h (1) Egg s i z e / f i s h l e n g t h (2) F i s h l e n g t h / c l u m p s i z e (3) Egg s i z e / c l u m p s i z e (d) L a r v a l weight (1) Egg s i z e / f i s h l e n g t h (2) F i s h l e n g t h / c l u m p s i z e (3) Egg s i z e / c l u m p s i z e  6  *  0  —  Table X I A s  S i g n i f i c a n c e of d i f f e r e n c e s between beach l e v e l s .  Beach l e v e l comparisons  Time and p l a c e of sample B-L (1)  Spawning Bedwell Bay, 2 0 / 4 / 7 0 .  ( 2 ) Post-spawning (4 days) Icarus P t . , 1 7 / 3 / 7 1 .  L-E  M-H  H-T  —  #  B-M  L-H  *#  **  --  M-T  B-H  L-T  B-T  ##  **  0  —  **  —  0  0  *#  —  --  ( 3 ) M i d - i n c u b a t i o n (8 days) Nanoose Bay, 2 7 / 3 / 7 0 . ( 4 ) Hatching (16 days) Icarus P t . , 2 9 / 3 / 7 1 .  --  ON  

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