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Effects of rearing density on stress response in tank-reared juvenile steelhead trout, (Salmo Gairdneri) Loftus, Kevin Kenneth 1983

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EFFECTS ON TANK-REARED  JUVENILE  OF  REARING DENSITY  STRESS RESPONSE IN S T E E L H E A D TROUT,  (SALMO G A I R D N E R I )  by KEVIN  B.Sc,  KENNETH  Guelph  LOFTUS  Univ.,  Guelph,  1978  A THESIS THE  SUBMITTED IN PARTIAL F U L F I L L M E N T R E Q U I R E M E N T S FOR T H E D E G R E E OF MASTER OF S C I E N C E in THE F A C U L T Y OF GRADUATE S T U D I E S (Department of Zoology)  We  accept this thesis required  THE  @  as conforming standard  U N I V E R S I T Y OF B R I T I S H J a n u a r y 1983  Kevin Kenneth  to the  COLUMBIA  Loftus,  1983  OF  In  presenting  requirements of  British  it  freely  agree for  this for  an  available  that  I  by  understood  that  his  that  or  be  her or  shall  DE-6  (3/81)  the  be  shall  and  study.  I  copying by  allowed  Columbia  the  Library  publication  not  of  University  the  of  of  make  further this  head  representatives.  of  The U n i v e r s i t y o f B r i t i s h 1956 Main M a l l Vancouver, Canada V6T 1Y3  at  granted  permission.  Department  fulfilment  the  extensive  may  copying  f i n a n c i a l gain  degree  reference  for  purposes  or  partial  agree  for  permission  scholarly  in  advanced  Columbia,  department  for  thesis  It  this  without  thesis  of  my  is  thesis my  written  i i  ABSTRACT The effects of rearing density on stress response in j u v e n i l e s t e e l h e a d t r o u t (2-60 g r a m s ) were e x a m i n e d i n a series of experiments. F i s h r e a r e d a t h i g h d e n s i t i e s showed evidence of s t r e s s , however, b o t h the m a g n i t u d e and the nature of the response v a r i e d with size. In the first study, fry (initial w e i g h t 2.35 gm) were r e a r e d a t 2 t e m p e r a t u r e s (12.5 and 15.0 °C) a n d 3 d e n s i t i e s (0.6 t o 3.0 times conventional d e n s i t i e s ) . F i s h r e a r e d at the high temperature showed a greater response to d e n s i t y than those r e a r e d a t t h e low t e m p e r a t u r e . At 15 ° C , growth rates were depressed by high densities, h o w e v e r t h e e f f e c t was of s h o r t d u r a t i o n and e v i d e n t only during the first 2 of 8 weeks. Wholebody proximate composition was affected. At high d e n s i t i e s , m o i s t u r e and p r o t e i n l e v e l s were e l e v a t e d , and lipid levels were lowered. C o n d i t i o n f a c t o r s w e r e a l s o low i n f i s h reared at high d e n s i t i e s . Both c o n d i t i o n factors and growth rates followed a c u r v i l i n e a r pattern with time. A t 12.5 °C, growth rates, proximate composition and condition factors followed trends close to t h o s e a t 15 ° C , h o w e v e r , t e s t s w e r e rarely significant. Plasma Cortisol concentrations were unaffected by either density or temperature. Activity was a f f e c t e d by d e n s i t y , b u t n o t by temperature. F i n g e r l i n g t r o u t ( i n i t i a l w e i g h t 15 gm), were differently affected over an 8-fold range in d e n s i t y ( 0 . 6 t o 4.8 times conventional levels). At h i g h densities, growth rates were suppressed, a n d t h e e f f e c t was of l o n g e r d u r a t i o n than o b s e r v e d in the f i r s t experiment. Whole body c o m p o s i t i o n followed the same pattern with density as in the f i r s t e x p e r i m e n t , but condition factors responded in the opposite direction, increasing at high d e n s i t i e s . Plasma C o r t i s o l concentrations w e r e u n a f f e c t e d by d e n s i t y . Rapid increases in density induced a r e s p o n s e i n growth r a t e s over and above t h a t due to density alone, which s u g g e s t e d t h a t f i s h become c o n d i t i o n e d t o r e a r i n g densities. Rapid r e d u c t i o n s i n d e n s i t y d i d not a f f e c t growth. Growth r a t e s and plasma Cortisol concentrations of presmolts and smolts were u n a f f e c t e d by a n 8 - f o l d d e n s i t y r a n g e ( 0 . 4 t o 3.2 times conventional levels). However, after an acclimation period, sudden increases in density caused s i g n i f i c a n t r e d u c t i o n s i n growth (greater than that expected on the basis of d e n s i t y a l o n e ) and e l e v a t i o n s i n plasma C o r t i s o l concentrations. Whole body composition followed a similar pattern with density as o b s e r v e d w i t h s m a l l e r f i s h suggesting that the lack of growth responses to density, does not necessitate a l a c k of s t r e s s r e s p o n s e . Condition f a c t o r data were i n c o n c l u s i v e . A c t i v i t y l e v e l s were u n a f f e c t e d by d e n s i t y , but d i d v a r y w i t h time. After exsposure to a salt water challenge test, f i s h reared at high d e n s i t i e s r e g u l a t e d plasma sodium levels less efficiently than fish reared at low densities. Flow rates and container volumes did not  significantly  affect  stress  response.  These r e s u l t s i n d i c a t e that high density rearing induces physiological, and possibly behavioral changes, i n steelhead trout. T h i s suggests t h e f i s h a r e showing a stress response. There i b evidence that, in some cases, f i s h may a d j u s t t o d e n s i t i e s , and that changes i n d e n s i t y , not density per se, may influence the stress response. G r o w t h r a t e s , when u s e d a l o n e , are inadequate i n d i c a t o r s of s t r e s s .  i v  T A B L E OF C O N T E N T S ABSTRACT L I S T OF T A B L E S L I S T CF FIGURES ACKNOWLEDGEMENTS General Introduction Study s i t e and r e a r i n g f a c i l i t i e s Water s u p p l y and q u a l i t y Environmental control f a c i l i t i e s G e n e r a l methods Culture practices Broodstock c o l l e c t i o n and i n i t i a l r e a r i n g Food and f e e d i n g Environmental control Temperature Photoperiod D a i l y maintenance Water q u a l i t y S e l e c t i o n of rearing d e n s i t i e s Sample c o l l e c t i o n Anaesthetic Lengths and weights Total weights Proximate a n a l y s i s Blood c o l l e c t i o n Behavioral Observations Experiment 1 : Stress Responses i n f r y Introduction M a t e r i a l s and Methods Results Growth Proximate a n a l y s i s Moisture Protein Lipids Ash Cortisol Weight l e n g t h r e l a t i o n s Behavior Net a c t i v i t y Total activity Water q u a l i t y Conclusions E x p e r i m e n t 2: S t r e s s r e s p o n s e s i n f i n g e r l i n g s Introduction M a t e r i a l s and Methods Results Growth Proximate a n a l y s i s Moisture Protein Lipids  i i v i v i i viii 1 11 11 12 13 13 13 14 16 16 16 17 18 19 21 21 21 21 22 22 24 26 26 27 29 29 38 38 41 41 42 43 43 49 50 51 54 55 60 60 61 63 63 72 73 73 76  V  Ash 77 Cortisol 77 Weight l e n g t h r e l a t i o n s 78 Water q u a l i t y 80 Conclusions 82 E x p e r i m e n t 3: s t r e s s r e s p o n s e s i n s m o l t s a n d p r e - s m o l t s ... 84 Introduction 84 M a t e r i a l s and methods 86 Results 93 Growth 93 E x p e r i m e n t 3a 93 E x p e r i m e n t 3b 96 E x p e r i m e n t 3c 101 Proximate Analysis 102 E x p e r i m e n t 3a 102 E x p e r i m e n t 3b 105 E x p e r i m e n t 3c 107 Cortisol 107 E x p e r i m e n t 3a 108 E x p e r i m e n t 3b 111 E x p e r i m e n t 3c 112 Weight Length R e l a t i o n s 113 E x p e r i m e n t 3a 113 E x p e r i m e n t 3b 115 E x p e r i m e n t 3c : 115 Behavior 116 E x p e r i m e n t 3a 116 E x p e r i m e n t 3b 117 S a l t Water C h a l l e n g e T e s t 123 Conclusions 127 E x p e r i m e n t 3a 127 E x p e r i m e n t 3b 128 E x p e r i m e n t 3c 130 General Discussion 132 Stress responses i n f r y 133 Stress responses in f i n g e r l i n g s .139 S t r e s s responses i n smolts and p r e s m o l t s 142 References Cited 150 Appendix I. A n a l y t i c a l composition of a r t i f i c a l sea s a l t . .161  LIST  OF  TABLES  T a b l e 1. P r i m a r y , s e c o n d a r y a n d t e r t i a r y l e v e l r e s p o n s e s t o stress 9 T a b l e 2. Summary o f t e m p e r a t u r e f l u c t u a t i o n s between tanks within experiments 17 T a b l e 3. D e s i g n o f e x p e r i m e n t 1 28 Table 4. Analyses of variance of growth slope data f o r experiment 1 33 T a b l e 5. E x p e r i m e n t 1. C o r t i s o l data 44 T a b l e 6. E x p e r i m e n t 1. C o n d i t i o n f a c t o r d a t a summary. 46 T a b l e 7. W a t e r q u a l i t y d a t a f o r e x p e r i m e n t 1 55 T a b l e 8. D e s i g n o f e x p e r i m e n t 2 62 T a b l e 9. A n a l y s i s o f v a r i a n c e of growth slope data for experiment 2 70 T a b l e 10. E x p e r i m e n t 2. C o r t i s o l d a t a summary 78 T a b l e 11. E x p e r i m e n t 2. Summary o f c o n d i t i o n f a c t o r d a t a . . 79 T a b l e 12. W a t e r q u a l i t y d a t a f o r e x p e r i m e n t 2. 81 Table 13. Physiological changes which occur during the parr-smolt transformation i n salmonids 85 T a b l e 14. D e s i g n o f e x p e r i m e n t 3 87 T a b l e 1 5 . Summary o f d i s s o l v e d o x y g e n d a t a for experiment 3 90 Table 16. Analysis of v a r i a n c e of growth slope data f o r experiment 3, p a r t A 96 T a b l e 17. A n a l y s i s o f v a r i a n c e o f growth slope data for experiment 3, p a r t B 99 Table 18. Analysis of v a r i a n c e of growth slope data f o r experiment 3, p a r t C ...102 T a b l e 19. E x p e r i m e n t 3, p a r t s 2 a n d 3. W h o l e b o d y proximate composition 1 06 T a b l e 20. E x p e r i m e n t 3. C o n d i t i o n f a c t o r d a t a summary 114 T a b l e 21. E x p e r i m e n t 3, p a r t 2. Summary of net activity d a t a by t r e a t m e n t a n d t i m e 121 Table 22. Experiment 3, p a r t 2. Summary o f t o t a l activity data 122 T a b l e 23. D e s i g n o f s a l t w a t e r c h a l l e n g e t e s t 126  vii  LIST  OF  FIGURES  F i g u r e 1. C h a n g e i n w e i g h t o v e r time by temperature and density f o r experiment 1 F i g u r e 2. G r o w t h s l o p e s a g a i n s t t i m e f o r e x p e r i m e n t 1 Figure 3. Histograms of proximate composition data for experiment 1 F i g u r e 4. C o n d i t i o n f a c t o r s a g a i n s t t i m e f o r e x p e r i m e n t 1. F i g u r e 5. E f f e c t o f f i s h density on activity levels in experiment 1 F i g u r e 6. C h a n g e i n w e i g h t w i t h t i m e f o r e x p e r i m e n t 2 F i g u r e 7. G r o w t h s l o p e s a g a i n s t t i m e f o r e x p e r i m e n t 2 Figure 8. Histograms of proximate composition data for experiment 2 F i g u r e 9. C h a n g e s i n w e i g h t o v e r t i m e f o r experiments 3a, 3 b , 3c Figure 10. G r o w t h s l o p e s a g a i n s t t i m e f o r e x p e r i m e n t s 3a, 3 b , 3c F i g u r e 11. H i s t o g r a m s o f proximate composition data for e x p e r i m e n t 3a F i g u r e 12. H i s t o g r a m s o f p l a s m a C o r t i s o l c o n c e n t r a t i o n s f o r e x p e r i m e n t s 3 a , 3 b , 3c F i g u r e 13. A c t i v i t y a g a i n s t t i m e f o r e x p e r i e m t 3 Figure 14. Plasma sodium concentrations following salt water c h a l l e n g e t e s t  30 35 39 47 52 65 68 74 94 97 103 109 118 124  viii  ACKNOWLEDGEMENTS I would l i k e t o express g r a t i t u d e t o my supervisor, Dr. T.G. Northcote f o r h i s e n c o u r a g e m e n t , and f i n a n c i a l s u p p o r t . Dr. J.D. M c P h a i l d e s e r v e s considerable thanks f o r assuming supervisory duties during Dr. Northcote's sabbatical. His p a t i e n c e and thorough efforts i n reviewing the d r a f t s were appreciated. S p e c i a l thanks t o D r . A.F. T a u t z of t h e F i s h and W i l d l i f e Branch f o r h i s encouragement, guidance and s u p p o r t , without w h i c h , t h i s s t u d y would n o t have been c o m p l e t e d . He a n d I s p e n t many h o u r s p l a n n i n g a n d d i s c u s s i n g t h i s research. Dr. Tautz a r r a n g e d a c c e s s t o t h e F r a s e r V a l l e y T r o u t H a t c h e r y and p r o v i d e d f i n a n c i a l a s s i s t a n c e . He a l s o r e v i e w e d s e v e r a l d r a f t s . Dr. P.A. Larkin provided encouragement and a d v i c e a t s e v e r a l stages during the study. His financial contribution, which covered a major p o r t i o n o f t h e m a t e r i a l c o s t s , was b o t h i n d i s p e n s i b l e , and a p p r e c i a t e d . H i s comments on t h e f i n a l d r a f t were most u s e f u l . Mr. U.H.M. Fagerlund and Dr. D.A. Higgs of the Department o f F i s h e r i e s a n d Oceans p r o v i d e d a d v i c e whenever r e q u e s t e d , a n d were i n s t r u m e n t a l i n d e f i n i n g t h e p r o b l e m . Mr. Fagerlund also r e v i e w e d a number o f d r a f t s . T h e i r support and e n c o u r a g e m e n t was g r e a t l y a p p r e c i a t e d . Drs. G. G r e e r , J.R. M c B r i d e , a n d D . J . R a n d a l l provided advice on s e v e r a l occassions. Dr. Greer k i n d l y arranged f o r t h e use o f t h e v i d e o e q u i p m e n t . der  S p e c i a l t h a n k s t o B a k h s h i s h D o s a n j h , H e l e n Dye and G l e n v a n K r a a k f o r p r o v i d i n g t e c h n i c a l a d v i c e w i t h sample a n a l y s e s .  The f o l l o w i n g people deserve credit and thanks for providing technical assistance with sample c o l l e c t i o n : Paul B e n t z e n , L i n d a B e r g , G a r y B i r c h , M i c h a e l F a t t o r i , Ron G r i f f i t h s , M i k e H e n d e r s o n , M i c h e l e Skwarok, A l S t o c k w e l l , Leonardo Tiro, and J o h n W e r r i n g . Sincerest thanks a r e extended t o the r e s e a r c h s t a f f a t t h e h a t c h e r y ; Bob L a n d , L a r r y M i t c h e l l , a n d M o r l e y Rempel, who c a r e d f o r my f i s h when I was n o t a t t h e h a t c h e r y . These gentlemen p r o v i d e d t e c h n i c a l a s s i s t a n c e , e n c o u r a g e m e n t a n d a d v i c e whenever requested. Their skillful efforts ensured t h e h e a l t h o f my f i s h , and s u c c e s s of the p r o j e c t . T h e i r a b i l i t i e s to suppress what must have been n e a r - h y s t e r i c a l l a u g h t e r d u r i n g some o f my more i n v e n t i v e moments, w i l l be remembered. Dr. Dave Z i t t i n , o f t h e B i o s c i e n c e Data Centre provided essential help w i t h programming a n d d a t a a n a l y s i s . H i s r a t h e r r e m a r k a b l e p a t i e n c e and good humour was a p p r e c i a t e d .  ix  Finally, a special thanks material support throughout this  to my effort.  family  for  moral  and  Personal support during this study was provided G r a d u a t e R e s e a r c h and E n g i n e e r i n g T e c h n o l o g y Award from the S c i e n c e C o u n c i l , and from Dr. N o r t h c o t e ' s NSERC g r a n t .  by a B.C.  1  GENERAL Fish  culturists  salmonids 1974)  North  America  i n hatcheries since the late  but with  rearing much  in  INTRODUCTION  little  densities.  an a r t a s a  selecting  scientific In t h i s  data  sense,  have  1850's guiding  fish  densities  remains  an  raising  (MacCrimmon their  culture  s c i e n c e , and e s t a b l i s h i n g  rearing  been  a l .  selection  of  has remained  as  adequate  important  et  criteria for  problem  in  fish  culture. Over  the past  50 y e a r s ,  salmon,  (Oncorhynchus  1975) .  Similarly,  the  province,  (Ford been  an  has  been  through  catches  Hart  increase  replenish  and  in  nature,  primarily  1969;  natural  determinants  balance al.  between  1981).  experience ability  who  some  to  understanding  gairdneri), with  salmonids  degree  survive this  optimal  efficiency  hatchery  the  stress  sports have  Larkin fish  a  of  in  declined  declines,  (Dill  regulate  method  has to this  hatcheries  1969;  I n h a t c h e r i e s , most  of the  operate,  and i t i s t h e  density. Usually  and f i s h  I f such  hatchery  response  densities  1981; A l l e n  survival  conditions i t i s probable  of s t r e s s . in  as  1977;  o p e r a t i o n , and management.  1962).  determines  these  efficiency  o f d e n s i t y no l o n g e r  economic  Under  important  Pacific  stocks. Associated with  the  dwelling  1966,  o f some  (MacLeod  propagation  natural  i n design,  Chapman  culturist  (Salmo  b e h a v i o r a l mechanisms  Fraser  fish  o f t h e most  increase  stream  through  declined  artificial  to  catches  Concomitant  supplement  improvements  have  trout,  1973).  an e f f o r t  In  spp.),  steelhead  1982;  commercial  stress a n d when  is  this (Birks that  reduces released,  essential  is a  to  et fish  their then fish  2  culturists  (Donaldson  Salmonid and  the  can  be  their as  culture  subsequent  depends  the  released  capable  of  Larkin  (1981)  released. with wild hatchery  He  and  also  salmonid stocking  rearing  in  the  wild.  in  hatcheries  Carpenter and  that  fish,  be  of long  often  wild  several  that  experience  stocks.  be  To  and well  achieve  behaviorally environment. used  in  p h y s i o l o g i c a l changes  may  affect  survival  large-scale genetic an  as  densities  inevitable  on  noted  on  when  interference  consequence  possible  subsequent  observed  and These  upon  differences  Atlantic  orders  the  (1966) s u g g e s t e d t h a t  of  a  the  suppression  on  of  in  of  smolts.  "normal"  was  behavior  reared  in  different  from  was  hatchery  of m a g n i t u d e above d e n s i t i e s  and  natural  salar)  influence that  survival  Fenderson  fish  of  conditions  behavior  release  suggest  and  artificial  (Salmo  over-crowding  studies  behavior  i n the  salmon  behavior  consequences  release.  territoriality)  addition,  lasting.  and  fish,  fisheries,  natural  high  Economic  released  natural  i n the  changes  have d i s c u s s e d  (aggression, In  on  the  influence behavior  hatcheries.  sports  fish  p r o g r a m s , even w i t h c a r e f u l management.  hatchery-reared  patterns  and  behavioral  may  environment.  s u r v i v a l of  growing  these  Chapman  (1958)  the  spawning,  s t a g e where the  p h y s i o l o g i c a l l y and  that  stocks  (1971)  Kalleberg  and  noted  Several-authors hatchery  must be  impose  fish,  into  pressures  suggested  may  reared  fish  artificial  to a development  to commercial of  1981a). involves  adequate  surviving  hatcheries the  on  reduction  success,  presently  released  contributions  to  Schreck  rearing  successfully  viability  1981;  in  found  to  densities, the  wild,  3  may  cause  changes  in  behavior,  and  in  turn  these  may  affect  survival. High number  density  of  released  rearing  physiological as  either  conditions  and  associated  et  al.  1981;  the  requirements of  hatchery  rearing  of  densities  observed  primarily  In by  been  fish  directed and  are  (Wedemeyer  1980)  it  at  behavioral  authors  and  are  is  note  that  during  most  the  sensitive  to  most  in  fish  culture  is  selecting  rearing  densities.  not  Stone  necessarily  (cited  in  returns  hatcheries  trial  and  density  Fagerlund  of  fish  (McLean  effects  increase  in  density  error  the  i s not  and  Increasing  production. et  reared  criteria 1979)  establishment  are the  understood  In  al.  1981)  under  high  established physiological (McLean  1979;  1981a). number  growth, streams.  high  does  and  underlying  Schreck  when  for  reductions  densities.  has  Dickhoff  exacting,  that  environmental  physiological  and  are  transformation  research the  a  species  pre-smolts,  Folmar  are  problem  criteria  Sandercock  A  smolts  influence  practices.  fundamental  rearing  basis  of  1981b;  to  most  s m o l t i f i c a t i o n . Many  smoltification  adequate  fact  with  Since  parr-smolt  Extensive  Schreck  process  or  understanding  changes  i s known  processes.  the  important.  identifying  salmonids  smolts  affecting  potentially  A  of  studies  survival,  and  Kalleberg  densities and  of  that  of  S.  under  the  competition  (1958) salar such  examine  noted and  in  that  brown  conditions  effects natural  territories  trout,  Salmo  subordinates  of or  density  on  simulated  disintegrated trutta, were  were  displaced  4  to  areas  where  growth  suggested  that  the  salmonids  are  fixed  physiological (1969)  Allen not  shrink  of  high  and  minimal but  space  that  observed  that  below a c e r t a i n  (1974)  in  l e v e l s of a g g r e s s i o n  Kawanabe  (1969)  described  fish  was i n h i b i t e d and a l l  densities,  surplus  some  food  o t h e r s were d i s p l a c e d low  densities, These  conditions, as  i n some s p e c i e s  would  suggest  when p r e y  behavior  individuals  made  growth.  At  grew  disappear),  will  be  suppressed.  In  as densities  become h i g h ,  some  In  At  rates species  of  while At  well.  semi-natural salmonids  limited  food,  also  may d e c r e a s e  some  individuals  under  territories  minimum t e r r i t o r y  middle  poorly.  many  of  sizes  in this  grew w e l l ,  and  conditions  densities  behavior  a n d grew  natural  Territory  and g r o w t h  response to  high  and  noted  decreased.  well.  generalizations.  increases.  They  behavioral  territories  under  when  affecting  a r e a s and grew  under  several  however,  juvenile  l e v e l s were  territorial  rarely  others,  that  of  territorial  (but  conditions,  observed  streams.  unusual  occupied  increase  conditions  densities  without  from p r e f e r r e d  a l l fish  under  (1965)  artificial  an  were  studies  densities  aggressive  In  food.  Chapman  conditions,  fish  by  with  i n t h e ayu, P l e c o g l o s s u s a l t i v e l i s •  under  moderated  made s i m i l a r o b s e r v a t i o n s on r a i n b o w  gairdneri,  and  territorial  associated  increased  (1966)  Chapman  be  sizes  kisutch,  increased  density  can  factors  and  f o o d abundance a l l o w e d  Salmo  they  minimum s i z e , even  Mason  Slaney and N o r t h c o t e  reduced.  r e q u i r e m e n t s of  territory  coho s a l m o n , O n c o r h y n c h u s  trout,  were  psychological  densities.  increased  rates  surplus  food  disintegrate.  sizes  are reached  5  surplus  fish  are displaced  and r e g a r d l e s s  of food  supply,  grow  poorly. Several of  density  laboratory  on g r o w t h  latipes,  diminished made  similar  (1946a,b) optimum  degree  densities  densities.  observed  1976;  various et a l .  Brauhn  et  density-related differences rearing  evaluated  were  In  was  within  each  made  of  most  to  poorly  studies  water to  density  i n growth may  be  from More  rearing  have  et a l .  a l . 1981;  and  Kittleson  have  described  these  differences  analyses  the  conditions  et  also  described  changes  an  higher (but  (Andrews  however  size  make  value.  density  1977; R e f s t i e  of f i n a l  Such  Brown  with  (Fagerlund  however,  experiment.  pulcher.  of the r e s u l t s  punctatus  studies  detect  (1972)  hatchery  high  depression;  too  Minchen  limited  Under  Other  food  territories  hatcheries  be a t t r i b u t e d t o e i t h e r  on t h e b a s i s  effort  1976).  of  olds.  i n hatcheries  with  (Oryzias  d e n s i t i e s and detected  facilities  Ictalurus  1981; R e f s t i e  growth  abandoned.  in  salmonids  a l .  could  methods  evaluation.  associated  in catfish,  and  Trzebiatowski  rates  of  Aquidens  studies  viable)  growth  1971),  found  conducted  medaka,  regardless  i n f r yand 2 year  are studies  economically  were  at different  production  the consequences  advantages  cichlid  a n d some l a b o r a t o r y  meaningful  been  to fish  the  that  the  they a  of crowding  extrapolation  reduced  on  S. t r u t t a  high  ecological  eventually  examined In  found  densities  findings  grew  The  (1962)  at high  and  have  and aggression.  Magnuson  availability,  studies  growth  q u a l i t y or the allow  critical  effects alone, rates  and over  essential  were no time to  6  understanding Growth assessing (1981)  density-related alone  density  examined  number  of  health.  is  variables As  mentioned  et  at  densities.  they  must  a l .  be  (Conte  and  studies  describing  densities effects. related  affect  salt  Wagner  may  Therefore survival  exist  for  Because  i t  returns  from  effects  of  confounded  Since  et  al.  by  in  assessing  and  Stone  may  effects. Bilton time  by be  (1978)  and  size  adult  returns.  unclear  i f size  at  They  in  useful, time  rate  of  the  of  return  results  reared  under  of  high  time-related  measuring et  release, found  fish  are  and  Bilton  a  reared  and  or  on  (cited  size  size  a l .  coho  trends  1980),  not  and  of  for  et  stress  both  fish  either  studies  Fagerlund  returns  tolerance  returns  affected  useful  density/return  reduced  indicator  density-induced  cautiously.  both  1981).  reduced  water  such  adequate  Sandercock  Wedemeyer  that  independantly,  of  1965;  be  demonstrated  values  Although  an  a l .  them  reported  interpreted  can  et  earlier,  1981)  release  (Birks  found  phenomena.  not  consequences and  Fagerlund high  probably  effects the  growth  densityal.  (1980)  when  varied  that  optimum  have  affected  each. is  juveniles rearing  reared  under  densities  on  differences different  ocean  densities,  s u r v i v a l are  not  the well  established. To and  s u r v i v a l of  evidence some  summarize,  that  species.  regimes,  water  the  effects  of  hatchery-reared  high  rearing  However, quality  rearing salmonids  density in  some  may  are  reduce  studies,  v a r i a t i o n s , and  density  on  the  unclear. growth  There rates  inappropriate  difficulty  in  growth is in  feeding comparing  7  growth  rates  findings. been  Because  rates  One  ultimately, developing the  an  gaining rearing  response  stress. are  stress.  examination Before  of  to  Evidence  of  The c o n c e p t  of stress  received  considerable  the f i r s t  definitions:  fish  and c u l t u r e of  fish  of  reared  demonstrable  attention.  have  by  at  high  experienced through  parameters.  definition  of " s t r e s s " i s  to biological  Selye  l i e in  strategies for  may  as a p p l i e d  and  perceived  must  a  of  the  health,  the fish be  not  clear.  may  of stress  and behavioral  further,  on  environment,  rates  this  of p h y s i o l o g i c a l proceeding  densities  to stress,  then  have  to survival  i s f a r from  of the l e v e l s  suppressed,  distorted  understanding  natural  I f growth  have  guidelines  the significance size,  i n the  weights  density  , not absolute  of d i f f e r e n t  their  densities  required.  suitable  an u n d e r s t a n d i n g  controlling  some  p e r se  survival  fish,  of d i f f e r e n t  Furthermore,  approach  consequences  groups  of t h i s ,  established.  growth  has  among  (1950)  systems  proposed  one  "the sum o f a l l t h e p h y s i o l o g i c a l r e s p o n s e s by w h i c h an a n i m a l t r i e s t o m a i n t a i n o r r e - e s t a b l i s h a normal metabolism in the face of a physical or chemical force."  Since most  then, useful  stress  has been  definitions  re-defined  i s that  many  of B r e t t  times.  One  of  the  (1958):  "stress is a s t a t e p r o d u c e d by any e n v i r o n m e n t a l o r other factor which extends the adaptive responses of an animal beyond the normal range, or which disturbs the normal f u n c t i o n i n g to such an extent that the chances of s u r v i v a l are s i g n i f i c a n t l y reduced. "  Seyle's  (1950)  account  of s t r e s s  introduced  the concept  of  8  the  general  is  a  adaptation  common  (including responses to  that  their  disease, to  nature.  a  to  can  during  the  resistance  physiological,  morphological  i f adaptation may  adaptation the  stage  fish  be  occurs,  reduced.  will  levels  (Schreck  1981a;  e t a l . 1977).  effects  (Table  effects  1981). al. 1978;  the  stimuli Stimuli  1980),  past on have  et  These  of  specific  regardless of  of r e s i s t a n c e , and a stage  of  the  divided  1973, 1 9 5 0 ) .  The  initial  by t h e r e l e a s e  in  take  place.  to absorb  i s  severe enough  been  duration, lethal.  defined  1981; Wedemeyer  secondary  other  enough,  i s usually  have  are primary,  occurs  changes  This  and McLeay  various  biochemical,  stress  to stress  or  which  capacity  reached.  of  adaptation  or i f i t i s of long  Wedemeyer  totality  3  an a n i m a l s '  be  stimuli  into  and b e h a v i o r a l  15  years,  fish been  has  and  (Mazeaud Yasutake  a l . 1981;  a considerable developed,  examined  investigated  anaesthesia  Wedemeyer  (Fagerlund  may  this  and  in  1980;  tertiary  1).  of s t r e s s  inducing  reactions  stage,  of response  Mazeaud  Over  o f some  i s not l e t h a l ,  If  not occur,  of exhaustion  Three  The  to a l l stimuli  Selye  I f the s t r e s s  of s t r e s s  conveniently  stage  terms  etc.).  i s u s u a l l y accompanied  hormones.  stresses  be  1980;  stress  Even  common  In simple  variety  pain,  reaction, a  (Wedemeyer  reaction,  wide  i s composed  and others  T h e G.A.S.  (G.A.S.).  a  fright,  stressor  an a l a r m  exhaustion alarm  response  stimulus,  stages:  syndrome  (for  include  a  interest  i n the  many  stress-  and review,  see P i c k e r i n g  transportation  e t a l . 1977; S t r a n g e 1977),  Wedemeyer  loading  1976),  (Barton and  and  social  et  Schreck density  heirarchies  9  level  T a b l e 1. Summary of primary, secondary r e s p o n s e s t o s t r e s s ( f r o m Wedemeyer a n d  Primary  Effects  (i)  release of a d r e n o c o r t i c o t r o p h i c hormone (ACTH) from the adenohypophysis; r e l e a s e of " s t r e s s hormones" (catecholamines and c o r t i c o s t e r o i d s ) from the interrenal.  (ii)  Secondary  Effects  (i)  b l o o d c h e m i s t r y and h e m a t o l o g i c a l changes (hyperglycemia, hyperlacticemia, hypochloremia, leucopenia, reduced blood c l o t t i n g time); tissue changes (depletion of liver glycogen, interrenal vitamin C depletion); metabolic changes such as negative nitrogen b a l a n c e and oxygen debt; diuresis with resultant osmoregulatory dysf u n c t i o n due t o e l e c t r o l y t e loss.  (ii) (iii) (iv)  Tertiary  Effects  (i) (ii) (iii) (iv) (v) (vi) (vii)  (Ejike  i m p a i r e d growth r a t e and f o o d c o n v e r s i o n ; delayed mortality; impaired parr-smolt transformation; impaired normal m i g r a t o r y behavior; reduced spawning s u c c e s s ; a l t e r e d body c o m p o s i t i o n ; increased s u s c e p t i b i l i t y to disease.  and  Schreck  1967),  high  Barton  et  handling al.  1978;  al.  1977;  and  Lorz  Hill  1981;  density  Noakes  (Barton  et  1978;  and  exercise  demonstrated  1976; 1976;  McLeay  Fromm  fright  a l . 1980;  Wedemeyer Wedemeyer  and  1968),  behavior (Zalnik  and  confinement  a l . 1980),  and  migration and  and tertiary McLeay, 1981)  (Specker  induced Strange  Wedemeyer Gordon  (Schreck  measurable  1970),  stress  and  1980;  Specker Most  responses,  and  et  (Mazeaud  et  (Schreck  Dye  1975;  a l . 1977), and of  Schreck these and  or  Bouck  contaminants  et  1980;  capture  disease  Donaldson  1980).  Erickson  Schreck  Schreck  (Strange  1981b;  1977;  chase,  1972),  1977;  Goldspink  by  and  Wedemeyer  temperature  and  Leatherland  smolt 1980)  studies a l l  have  10  contributed  t o an  improved  cultured  fish.  attempted  t o measure t h e  reared  for  However,  changes  in  assessing  and  consideration steelhead  stress  of  a primary  (Donaldson  in  results  of  Cortisol),  (1981)  1981)  i t has of  a  number  that  To  might  trout. of  one  several body  it  responds  important  selected  either  because o f  signify  in  primary  immediate use a  to  thorough  indicator  of  tertiary  indicators  condition,  activity,  was  quickly on  selected to  (1978). their  metabolic  stress  metabolic  e x c e s s C o r t i s o l l e v e l s as Laycock  other  useful  A  primary  effects  and  i n them would  of  be  attain  i n Lee  because changes  fish  and  described  were  by  e f f e c t s of density,  be  stress,  and  because  and  have  its  t o l e r a n c e ) were m o n i t o r e d . C o r t i s o l  indicator  mammals a r e  al.  of  and  steelhead  facilities. effects  et  experienced  on  variables  the  processes. E f f e c t s  measures  and  proximate compostion,  salt-water  osmotic  that  the  (plasma  growth  juvenile  production  (growth r a t e ,  as  in  was  understanding  t o examine the  on  requirements  variables.  behavioral  stress  stress  the  under d i f f e r e n t d e n s i t i e s ,  physiological  density,  of  Fagerlund  l e v e l s of  study attempted  physiological  and  only  extended p e r i o d s  c o n s e q u e n c e s on This  understanding  observed  The  other  sensitivity, or  and  or  behavioral  changes. In no  a l l experiments  effect  on  any  of  the  the  null  hypothesis  measured  variables.  was  that  density  had  11  STUDY All  experiments in  Abbotsford,  facility  is  operated  output  anadromous steelhead  water  constant  nearly 200  and  84.0  at the Fraser  Columbia.  Ministry  production  of c o a s t a l  of  of  cutthroat  supply  obtained  i s passed  trout,  Valley  Trout  This  provincial  the  Environment.  parr  and  smolts  of  Salmo  clarki,  and  a  throughout  the year - 7.8  levels  aquifer,  units.  respectively,  tower  and t o t a l  quality  Before  t o remove  C.(±  Specific  water  available  of production.  .2),  excess  Temperature and  pH  conductance hardness  and f o r a c o a s t a l  Overall,  is  to saturation.  a t 9.5°  t o 230 umho/cm. A l k a l i n i t y  buffered.  local  an a e r a t i o n  oxygen  mg/1  quality  f o r a l l phases  through  a t 7.5  and  from  and to bring  moderately  culture.  the  quantities  constant  from  is  water,  sufficient  nitrogen, is  FACILITIES  trout.  Ground  use,  British  includes  stocks  REARING  conducted  by  Water  in  AND  were  Hatchery  Hatchery  c  SITE  source i s ideal  are  is  ranges 71.0  t h e water for fish  12  Environmental  Most the  experiments  research  fibreglass fitted  cleaning.  section  tanks  with  were  central  by  outflows  f o r each  from  three  i n f l o w s : one  groundwater  temperature.  Each either  and  model  quantity  provided  was  504  a  heated, By  and  were  single accurate Each  one  oval,  available.  drains, with  Twelve  were  of tanks.  of  equipped both  Frequency food  timers by  cm)  enabling  pair  o r 708,  free.  Automatic  i n the quarantine  mixing  500  flow  litre, were  largely  self-  and  two  control,  were  received  and  one  temperature  in  These  overflow  unit  chilled,  room  at  water ambient  could  be  accurately. tank  vibration  77  each  constructed  controlled  conducted  bottom  boxes,  valve-regulated  facilities  of the h a t c h e r y .  ( 1 3 7 cm  Header  control  fed  at  provided  fluorescent  of  with of  an  which  feeding, each  operate  duration  feeding  photoperiod  lighting.  automatic  feeder,  silently  of each  were  control.  Ewos  and  feeding,  controllable.  Illumination  was  13  GENERAL  Culture  Broodstock  The  collection  initial  rearing  carried run,  collection  o u t by  of  of  late  the  During  egg  1979,  take,  phenoxyethahol.  Ripe  wiped  then  eggs  clean,  and  to f a l l  males  was  During  water  an  into  mixed  Heath  batches When  stage,  starter  were  fish  a clean, i n and  up  until  were these  eggs  in these  and  experiments  were  at the hatchery.  The  mid-April, were  Adult  captured  collection  were  period  dry bucket. t h e eggs  erythromycin  by  with  cardiac  the vent  Sperm were  extended  1980.  bled from  early  by a n g l i n g  anaesthetized  anteriorly  then  from  trays.  from  2-  puncture,  a l l o w i n g the  at  rinsed  phosphate  reared  were  least  several  ( 4 0 ppm)  time  to  170  per trough. a mean  two  times.  was  used  t o 1.8  m circular  their  weights  of  placed  t o swim-up, from  reached  litre  They  weight  were  ranging  10% o f t h e a l e v i n s  fish  until  females  at temperatures  reached  transferred tanks  synchronize  transferred  t o 8000 they  individual  To  approximately  they  densities  they  used  spawning,  antibiotic.  separate egg  until  slit  artificial  s t e e l h e a d were  females  hardening,  Fertilized  in  fish  of the system.  December,  rearing  broodstock,  the research s t a f f  the headwaters  from  practices  initial  C h i l l i w a c k - V e d d e r system  in  as  and  METHODS  were  tanks.  the  fed  1.2  gm  12  °C.  swim-up  troughs  at  Silver  Cup  at which  time  Rearing  averaged  different  7 to  ( 2 . 4 m)  in  continued  2.3' gm.  At  this  14  weight  Food  the  and  experiment  ensure  schedules  that  minimizing  reduce  Furthermore,  interactions.  both  those  frequency  found  less  sockeye than  or  off  varied  the  above,  could  fully  to  hours.  turn  every  15  minutes between  treatments  were  30 on  50  minutes  digest  minutes the  before  lights  and  seconds.  the  70  same  on  their average  aggressive  supply and  and  the  (1962) appetite  outcome  of  a p p e t i t e s of  gastric  of  their et  Brett  maximum  a l . (1973)  exhibited  rainbow  evacuation  Oncorhynchus  20°C  every  after  prey  and  Magnuson  temperature.  times  approximately  and  that  rate  sockeye,  3  thereby  fish.  and  and  Higgs  nerka,  reared  daily  ration  observed  greater  that  growth  daily.  i n f o r m a t i o n , i t was  and on  of  Shelbourne  satiation  this  (1974),  increased with gram  rations,  hunger-induced  demonstrated with  designed  should  interactions  in t e r r i t o r i a l  be  interactions  feedings  importance  aggression  closely  24  aggressive  Northcote  the  should  to excess  frequent  30-40  fed  fish,  15  of  that  frequently,  to  exposed  f r y fed continuously at  fish  gram set  of  rate  than  Given fed  and  of  experiments  decrease  a l . (1978)  evacuation  15°C  in  et  correlated  (1970) at  Slaney  interactions  trout that  and  evidence  Grove  are  likelihood  appetite  provided  in density  a l l fish  the  consequences.  on  started.  feeding  Feeding to  was  decided  that  fish  20  minutes  for  for  larger  fish.  lights  o f f . The At  frequency  small, Feeders  turned  d u r a t i o n of  any and  were  should  time,  the  on,  be 2-20  were and  feeding  however,  duration schedule.  a l l The  15  quantity  of  adjusting  the  To  feeder  using  in  grams,  incorporating hatchery  the  the  and  minimal,  I multiplied  fish an  basis  this with  is  Since  by  a  (dry clear  on  a  dry  a a  weight  basis)  that,  10%).  even  from  to  3.  dry  be  were  weight  of  that  not  allowing  always  conversion  content  Given  factor  Fish  to  of  would  allow  food  are  fish.  is  food  of  in by  matter  food  for  moisture  of  final  accurate  conversion  some  food  content  =  modified  simple  by  weight  fish  Wt  individual  factor  sufficient  (1981).  calculated  of  was  were  temperature  was  competition  amount  and  fish  should  then  frequently  p o s s i b l e . To  always  that  moisture 3:1  by  70%  and  conversion  uncommon  f o r waste,  in  excess  available.  Ideally,  visual  tank.  Tautz  reasonably  increases  average  i t  not  per  =  factor  feed  rates  where T  days)  weight  to  an  hatcheries,  morning,  amount  (assuming  of  was  in  9:1  feed  in  enabled  as  efficiencies  food  time  poor  average  as  controlled  Iwama a n d  i n gm,  adjustment  ensure  provided  efficiencies  =  by  weight  weight  fish  to  be  growth  (T/l000)*t:  model  minimum  of  +  3 3 3  increase  wasted,  therefore  t  projected  number  could  projected  developed  initial  This  of  multiplying  =  seasonal  data.  Calculating  Wo'  and  a  predictions  model  Wo  Celcius,  feeding  requirements,  =  3 3 3  each  plates.  a  Wt'  degrees  during  food  model,  weight  and  fed  estimate  calculated Their  food  confirm  inspections found  on  the  of tank  have  been  fed  to  satiation  early  each  thereafter. Logistically,  this  that  rations  periodic  food  waste  bottoms  were were  adequate,  made. S u r p l u s  immediately  after  first  feed  was  was  feeding  1 6  in  the mornings,  increased  throughout  reduction The  of  published  the  wasted  day.  at  This  successive suggests  i n these  experiments  was  the Moore-Clarke  Company  was  used  formulation  and  i t  a t -20°C  Environmental  feedings  a  voluntary  intake.  used  from  brand  stored  food  food  obtained This  and t h e amount  since is  until  i t s  known  t o be a  required  the  Abernathy  i n LaConner,  Washington.  specifications  suitable  in order  diet  feed.  to reduce  Feeds  are were  oxidation.  control  Temperature  The When  adjusted,  desired by  available  level  experiment  temperature  i t  and  could  range  be  maintained  fluctuations  in Table  extended  from  those  from  within levels  7  ±  to  18°C  0.5°C of t h e  are  summarized  2.  Photoperiod  As  described  fluorescent Brett growth  rates  averages finish  of  earlier,  t h e q u a r a n t i n e room  lights.  Dimmers  (1979)  noted  i n salmonids. the  number  of the experiments  were that To  not  were  eliminate  used  equipped  with  available.  changing  of hours  was  photoperiods can this  influence,  of d a y l i g h t to establish  affect simple  at the start  and  photoperiods.  1 7  T a b l e 2. Summary o f t e m p e r a t u r e f l u c t u a t i o n s between tanks within experiments. Fluctuations were not calculated for t a n k s h e l d a t 9.5 C , s i n c e most were r e c e i v i n g w e l l water, and well water temperatures fluctuated only slightly. I n c o l u m n 4, the greatest difference between mean tank temperatures over the d u r a t i o n of each experiment i s g i v e n .  EXPERIMENT  DESIRED TEMPERATURE celc ius  1a 1b 2 3  15.0 12.5 12.5 9.5  Daily  morning  individually allowed  header  MAX DIFFERENCE BETWEEN T I M E AVERAGES celc ius  0.17 0.21 0.66 0  0.13 0.15 0.21 0  maintenance  Each  also  MAX DIFFERENCE BETWEEN TANKS AT ANY TIME celc ius  box  feeders  examined  to ensure  feeding  outflows  were  activity were  manually  proper t o be  checked.  switched  functioning.  observed.  This  At'the  Temperatures  on  routine  same  were  and  time,  checked  frequently. To once  minimize  per  seconds during  week.  The  (excluding cleaning.  without  was  partial  More  quick  all-  time  and  fed vigorously  tanks  spent  were  on  draining  frequently,  s c r u b b i n g and  procedure usually  stress,  excess  each  tank  were  and  wastes  apparently  not  thoroughly  rarely  time). Fish  tanks  food  at the next  scrubbed  were  stressful  feeding.  exceeded not  partially were  only 30  removed drained  removed.  This  since  fish  18  Water  quality  Generally, water  quality  two  in density  proportionally all  treatments  and  per  unit  water  of  fish  (1957)  the  showed  high  energy that  as  Brett  recorded  consumption findings Davis  An was  to  and water  that  could  alternate estimate  provide quality Several  dissolved  measured  by  method  (Standard nitrate,  nitrogen  at  were  the  in  reduced and  at  with  the  treatments  the  addition Samples  the  as  are  can  ensure unit  be that  of  ideal  time  from  a  consequences. enough,  would  maintenance. varies  swimming  (30-50 with  adequate  swimming  sustained  gm),  speed. oxygen  velocity.  defined  by  These  Warren  and  flows. used  same  in these  water  experiments,  (next  flow.  section)  Differences  in  expected. monitored.  compounds.  nitrite  and  were  and  of  the  and  for  ammonia  Ministry  near  was  (Winkler)  analyzed  specific  collected  were  oxygen  iodometric  nitrate,  Laboratory  always  These  Dissolved  Samples  turbidity  were  per  requirements  1976).  pH,  to  of  azide modification,  total  tanks  i f high  cost  were  nitrogenous  flows  for position  high  water  one,  serious  tanks,  one  ensure  while  sockeye  the  Environmental  determined.  have  f o r growth,  Methods  nitrite,  of  variables  and  usually  can  to  water  approach,  metabolic  maximum  other  of  logarithmically  a l l tanks  In  This  that  method,  between  density  density  scope  be  the  oxygen  Environment.  high  square  increases  suggest  (1967),  the  taken In  expenditures  the  approximately  be  same a m o u n t  weight.  i n the  higher  (1964)  in  viewpoint,  flows  necessitate Fry  receive  can  experiments.  increased  quality  Increased  approaches  of  the  conductance the  central  19  bottom  drains.  Collection  time  varied,  but  was  always  in  the  afternoon.  Selection  of rear ing  The amount  s e l e c t i o n o f d e n s i t i e s was b a s e d  of water  steelhead In in  tanks  At  half  Quinsam,  high.  Robertson  for  upper  density.  fish  conventional  flow  of  permissible  conservative  Brett reared  conventional  minimum  was  and Blackburn  that  in  d e n s i t i e s of  0. k i s u t c h and  was a  as  estimate  an  at found  20 gm/1  could  oxygen  set  at  "B"  safety  common  but short  duration oxygen  6.0  of  found  as oxygen  that  were  The  used  minimum  This  closely  level.  This  level is  levels  should  schedule  reductions,  i n young were  not  of the experiments,  feeding  levels  levels  in a  mg/1.  stages  level  be r e a r e d  levels.  ( i ) oxygen  the f i n a l  (1981)  gm  densities are  hatcheries,  was u s e d  until  a t 15°C, as l o n g  coho,  metabolite  reasons:  feeding-induced  2 t o 60  rearing  2 gm,  acceptable  (1975)  level  and  of f i s h  safe  level  rearing densities  densities for steelhead.  t h e number  f o r three  this  examined  than  20 gm/1  rearing  Davis'  the frequent  minimize  of  rearing  and B i g Qualicum  Therefore,  oxygen  (1979)  greater  maximum  approximated  approach  ( i ) t h e maximum  for fish  steelhead  tshawytscha  weights  of water,  20 gm/1  hatchery, McLean  maximum  of the hatchery,  exceed  Creek,  determine  instead  (ii)  rarely  Oncorhynchus  that  To  section  Capilano  that  chinook,  given  a v a i l a b l e , and ( i i ) a knowledge  the research  weight.  upon:  rearing densities.  circular  only  densities  coho  should  and  and  maintained  ( i i i )  sockeye above  a  20  critical  minimum  conversion  of  4.0  efficiency  -  were  4.5  mg/1,  limited  neither  during  growth  6  to  8  nor week  experiments. Although rough  metabolite  estimates  concentrations ionized  to  quantity  of  levels.  The  levels  0.0125  EPA  based  remain  found  became  low  even  toxic et  at  al.  a  errors  at  1974)  in  Burrows  ammonia  high  densities.  Un-  were  estimated  by  which  expresses  the  pH  and  temperature  that  mg/1.  maximum  calculated,  that  recommends  0.010 safe  not  clear  form)  handbook  as  were  different  below  mg/1  procedure  on  rearing  First, the  consumption  mg  Fourth,  the  estimated  amount  was  were  un-ionized  Burrows  level, method  maximum  available  water  (1964)  however and  Westers  recommended  calculated. growth  probable  final  calculated  densities  oxygen  available  the  (above  per  probable  model  described  using  6  tank,  Second,  size,  involved  and  final  following  the fish  earlier.  approximate  the  ppm)  oxygen formula  comm.):  oxygen/fish/hour  to  of  of  using  the  rates  pers.  calculating  quantity  knowing  (Tautz,  for  temperature,  were  Third,  total  form  (1973)  0.003  It  (Liao  toxic  rates  mg/1.  steps.  sizes  (the  chart  (1977)  The five  a  should  Pratt  remain  levels  the  recommended  made.  would  ammonia  referring  and  were  production  determine  available  oxygen  =  the was  wt'  e  *  temp  maximum divided  (°C)  number by  *  of the  0.048  fish  per  expected  tank,  the  maximum  21  consumption  rate.  Finally,  density,  tank  volumes  per  were  known.  tank  to achieve  could  be  Sample  the desired  a d j u s t e d once  weight/volume  t h e number  of  fish  was  used.  c o l l e c t ion  Anaesthet i c  When  required,  The  c o n c e n t r a t i o n was  the  sampling  usually  and  These  proceedure.  measurements  first  Total  were  netted,  and weights  weeks  0.01  were  rare,  and  required  by  recovery  was  usually  taken  anaesthetized, Fork  and  l e n g t h s were  to the nearest  of the f i r s t  every  0.1  two  50  were  taken gm,  experient, they  weeks.  randomly  to the nearest  although  were  Fish  during  weighed  to the  gm.  weights  To weights  obtain were  an  procedure  and  rarely  not appear  exact  determined  anaesthetizing  did  Mortalities  f o r measurement.  millimeter,  nearest  a c c o r d i n g t o the speed  weights  quickly  selected  the  varied  rapid.  Lengths  were  the a n a e s t h e t i c 2-phenoxyethanol  measure  approximately  sampling  lasted  traumatic  o f mean  more  a l l than  since  fish  weight every in  a  two tank.  5 to 7 minutes.  fish  usually  by  The  tank,  total  weeks The  by  entire  experience  fed actively  at  the  22  next  opportunity.  Proximate  analysis  To body  determine  composition,  moisture, In  protein,  of  t h e growth  for  the t h i r d  experiment  were  killed  whole  analysed f o r  and ash content. fish  were  f o l l o w i n g 24 h o u r s  experiment fish  c o n d i t i o n s on  and s u b s e q u e n t l y  two e x p e r i m e n t s ,  killed,  until  were were  composition  fish  killed  at  the  of starvation.  collected  not  mid-way  starved,  testing  within  was  since  and  end  Samples  through  this  the  would  have  and  then  each  tank  o f 2-5 f i s h  Following  before  fish  from  on t h e b a s i s differences  Higgs  analysis.  forprotein  measured,  processing,  for sized-related  tanks.  used  weighed  During  two g r o u p s  homogenized  procedure  were  required. into  enabled  were  lipid  of r e a r i n g  growth.  divided  This  effects  were  studies  and  When frozen  fish  the f i r s t  affected  the  et  The  a l .  of  in  proximate  (1975)  automated  determinations  on  size.  fish  Kjeldahl  a  Technicon  AutoAnalyser I I .  Blood  c o l l e c t ion  Blood Considerable during minutes  samples care  sampling. between  acceptable  was  were  forCortisol  r e q u i r e d t o minimize  Fagerlund netting  maximum  collected  time.  ( p e r s . comm.; and  taking  Wedemeyer  determination.  the effects  of  1967) s u g g e s t e d  of the last and  sample  Yasutake  stress that  5  was a n (1977)  23  recommended  When  similar  For  24  fish  were  hours  fish  immediately  placed  concentration  prior  was  with  Schreck  1978;  began  roll,  to  weighed,  they  and  and  and  centrifuged removed  labelled frozen  a  until was  with  vials.  Fish  fish  one  individual  that  at  were  within  a l . 1977; 1977).  As  fish  measured  and  severed  lamda  centrifuge  similar  vial.  high  speed  and  dry  the  insufficient  same  on  500  2ml  If  pipettes  and  as  They  into  of  20-30  hormones  soon  heparinized  fish  and The  Strange  the  frozen  avoid  netted  stress  processed.  Pasteur  to  anaesthetization  in  emptied  second  to  three minutes  A l l samples  in  were  added  over"  assistants.  quickly  a  taken  individually,  two  disturbed.  quickly  "rolled  et  blood  collected  not  strong anaesthetic.  Yasutake  of  a l l fish  were  elevations  removed  were  was  demonstrated  and  was  Vials  then and  size  the  were serum  placed  i c e , and  was  in  remained  analysed.  Cortisol  samples  kit available  from  outlined  care  (Mazeaud  collected  i t s blood for  until  to  Blood  iced  most  have  were  fish  containing  reduced  handed  volume  selected,  was  that  Wedemeyer  peduncle  and  blood  such  tank, tanks.  bath  sampling  micropipettes. vials  in a  sampling,  a  in adjacent  sampling  associated  to  from  Several authors to  caudal  prior  removed  disturbing  seconds.  guidelines.  i n the  were  analysed  Clinical  manual  (see  Assay Ref.).  by of  radio-immunoassay, Canada.  Proceedures  using are  24  Behavioral  The  Observations  initial  enable  a  and  and a c t i v i t y  densities  observe  enabled with  12  to  With  the  fish.  Activity  were  to ensure  most  cases,  activity  appeared  were  filmed  Fish  Analysis  subject  individual though  estimates  fish  followed  individual  fish  Additionally,  within  could  be  be m e a s u r e d .  could  be  distribution  and the ease  were  for  at  least  disturbance for at  least  "normally".  within  both were  In  two t o  three  qualitative  and  difficult low  for  tanks  observations  to obtain  density  and a g o n i s t i c  However,  i n these  reduced.  little  the  followed  of making  p e r i o d , the.  minutes.  that  In  used  the camera  "normal"  aggression  be  because a l l  hour  behaving  for five  which  operating,  with  were  to follow  could  on t h e m o n i t o r  bias.  could  2-3  undisturbed  edge  showed  of  a  monitor  to observational  uncommon,  uniform,  then  fish  of the films  quantitative and  that  system  of  Because  recorder,  i n behavior  followed  minutes  video  Additionally,  left  t h e tank  was t h e n  treatments.  This  within  five  minutes.  used.  was t o  levels  a  television  be p o s i t i o n e d o v e r  the  Thus  of d i u r n a l changes fish  both  i t was d i f f i c u l t  was  made  observations  high,  t o the f i s h .  be  to filming,  hours.  could  could  effects  often  viewing,  of  different  fish.  disturbance  observations  Prior  within  individual  little  assessment  were  repetitive  possible  of the b e h a v i o r a l  quantitative  aggression rearing  objective  encounters,  at high  densities,  only  short  tended  to  varied  tanks,  times. be  non-  considerably  tanks.  Therefore  only  gross  measures  of a c t i v i t y  were  recorded.  25  The  two  variables  distance (the and  that  a  shortest end A  of  measured  given  distance  a  15  second  total  of  100  total  and  reduce  observational  periods 15  of  period,  of  50  seconds  were  erratic in  view,  and  Selection  on  total  distance  proportional completed. fish. some In  to  fish  these  cases,  to  decrease  five  separate  spaced  right  and  measures  activity  required terms fish the  were  not  avoid by  fish  be  net  those  at  total  activity the  start  associated  alternates  of  were  for  the  of  on  of  the  each  since  each  ten  fish field  each  fish.  fish  its  To  recording  be  neighbours. the  occassionally less  was  active  corrected  required  were high  the  filmed.  behavior  other.  the  with  (50  influence  half  from  would  fish,  was  tank  interval,  that  the  each  intervals,  made  measured,  activity  followed  were  selecting  fraction of  of  time  left  position  behavior  To  the  net  the  each  only  of  active  moved  not  of  for  throughout  the  problem  could  and  on  each  view.  and  activity  five  Measures  Another  that  evenly  observation of  day  of  in  (the  position  recorded  start  affect  field  was  the  of  the  fish's  At  adjacent  of  seconds)  each  behavior,  Immediately  During  a  bias,  criteria  could  between  15  analyzed.  both  distinguishable  in  activity  interval).  duration,  were  total  moved  observations  net)  selected,  one  fish  were  not  selected.  fish, by  a  viewing  possible  densities,  required  swim  length  for was of  out the  factor time these that time.  26  EXPERIMENT  1:  STRESS  RESPONSES  IN  FRY  Introduction  It  is  decrease small,  as  body  their  rapid,  small  easily  potential  than  that  the  i f present,  In at  three  a l l groups,  growing  mean  of  and  two  orders  times  stress,  natural  i f present,  conditions,  territorial  (Cole  artifical  conditions,  between  establish  and  were  juvenile  densities  territories.  be  1980),  result  animals When  cause,  small  hatchery to  Maximum  are  might stress  for  eight  densities stream  densities.  increase  of  Since  400-600%,  of  this  under  differences i f . the  fish  is  more  density-  readily detectable.  and  are  growth  natural  consequences  to  fish.  reared  above  steelhead  considerable might  in  f r y were  expected  should  Noakes  of  tends  density-induced  magnitude  conventional  weights  when  temperatures.  of  fish  i n d i v i d u a l s . One  r e a d i l y demonstrable  physiological/endocrinological  induced  levels  slower  steelhead  of  is greatest.  in  densities  and  growth  regardless  three  levels,  Therefore,  rates,  experiment,  several  rates  in  this  were  the  for  growth  consequences  be  attained  in  relative  increases.  variations  then,  should,  that  size  detected  expect  weeks  known  Under  size  these in  are  highly activity  attempt  to  27  Materials  Replicate 12.5  or  15°C, a t one  treatments The  groups  and  experiment  late  permissible  densities  were  p e r volume  to  design  3.0  times  Photoperiod automatically  On  minutes to  for  further  size  was  taken  fixed  1,  analysis  were  collected  On density  14,  and 32,  f o r proximate day  36, w a t e r  t a n k s , and  from  on  as  per  described 1/min.  tank.  The  On  extended  a  from  a t t h e h a t c h e r y . The  Lights  hours  and o f f a t  1900  minutes  plates  and  day  Also  on  were hours.  seconds every  adjusted day  each 23-24  frequently 39,  feed  inches.  lengths  61. Plasma and  feed  were  released.  58,  f o r 60  to  t o 4/64ths  and w e i g h t s ,  samples  on d a y  60  were  for Cortisol samples  were  the four  high  analysis. samples  were  the inflow.  sampling  was c o m p l e t e , w a t e r  time  a l l t a n k s . A l l samples  from  in  cycle.  individual 46,  terminated  12L:12D  adjusted-  quantity 3/64ths  days  densities  18-19  Feeder  weights,  final  densities  a  seconds.  on  collected  on  fed every  from  gm.  s e t a t 25  fish  6  2.35  calculated  1000  either w e i e  there  averaged  was  f l o w s were  at  3.  were  switched  and  were  on a t 0700  food  reared  In t o t a l ,  f r y weight 1980  and  feeders  control  Total  600,  i n Table  were  68  Water  conventional  was  39,  26,  predicted  switched  fish  day  200,  basis,  i s summarized  Initially,  Initial  densities  (General Methods).  f r y were  densities.  b e g a n on A u g u s t  Maximum  weight  time.  tanks.  1980.  three  steelhead  of three  October,  earlier  0.6  12  of  and Methods  collected On  samples were  day were  from  58,  after  Cortisol  again c o l l e c t e d ,  refrigerated  and  kept  this in  28  T a b l e 3. D e s i g n o f e x p e r i m e n t 1. Initial densities (gm/1) b a s e d o n i n i t i a l mean w e i g h t o f 2.35 g r a m s . F i n a l densities are p r o j e c t e d v a l u e s b a s e d o n g r o w t h s l o p e m o d e l (Iwama and T a u t z 1981) u s i n g t h e s e a s o n a l a d j u s t m e n t f a c t o r of T/1000 (see t e x t , page 1 5 ) .  TANK  TEMP NUMBER VOLUME Celcius litres  1 2 3 4 5 6 7 8 9 10 1 1 12  15.0 15.0 15.0 15.0 15.0 15.0 12.5 12.5 12.5 12.5 12.5 12.5  darkness 24  1000 600 200 1000 600 200 1000 600 200 1000 600 200  until  delivered  tanks  on d a y s Video  oxygen  25 25 25 25 25 25 25 25 25 25 25 25  4.0 2.4 0.8 4.0 2.4 0.8 4.0 2.4 0.8 4.0 2.4 0.8  DENSITY INITIAL gm/1  FINAL gm/1  9.4 5.6 1.9 9.4 5.6 1.9 9.4 5.6 1 .9 9.4 5.6 1 .9  60 36 12 60 36 12 48 29 10 48 29 10  to the environmental  concentrations  46 a n d 6 1 . A Y S I m o d e l  r e c o r d i n g s of f i s h  LOADING gm/l/min inflow  600 360 1 20 600 360 1 20 480 288 96 480 288 96  laboratory  within  were  determined  54 o x y g e n  behavior  meter  w e r e made  was  on d a y s  on a l l used. 25, 39,  53. Mortalities  usually by  INITIAL f/1  hours. Dissolved  and  250 250 250 250 250 250 250 250 250 250 250 250  FLOW 1/m  caused  gilling  were  by e i t h e r  recorded physical  i n the perforations  daily,  b u t were  damage w h i l e  of the inflow  rare,  being  pipe.  a n d were  netted,  or  29  Results  Growth During  the  difficulties feeder  course  of  the  r e s u l t e d in the l o s s  problems  lasting  four  of  tank  some  days,  r e s u l t e d in the l o s s of growth slope Similarly,  experiments, data.  between data  for  technical In  tank  days  14 and 32,  that  interval.  growth slope data was l o s t between days 32 and 46 for  12. A  plot  of  adjusted  fish  weights  against  (Figure 1) in which weights were c o r r e c t e d to a  time i s  common  a common i n i t i a l  weight and r e c a l c u l a t i n g  times using the growth slopes from figure  shows  expected, at density  the  increased,  Linear  time  coefficients  fit  It was  This  over time. As as  mean f i n a l weight d e c r e a s e d . At 1 2 . 5 ° C ,  the  were fit  were greater  revealed a consistent  specified  intervals.  weight  than at  weight  15°C,  but l e s s  r e g r e s s i o n equations  data  in  1 2 . 5 ° C . At  clear.  r e g r e s s i o n s of mean f i s h weights  against  treatments.  successive  changes  15°C, f i s h grew f a s t e r  trend was s i m i l a r ,  power  relative  s i z e s at  given  initial  s i z e . T h i s was accomplished u s i n g the grand mean s t a r t i n g as  4,  plotted the  data  in  the  the  each  closely  than 0 . 9 9 ) .  pattern  is unlikely  for  to  However,  one-third  treatment. (all  correlation  close  residuals  inspection  between  that the s l i g h t c u r v i l i n e a r i t y  of s u f f i c i e n t magnitude to e i t h e r  analyses.  all  in the  invalidate  use of the growth model (Iwama and Tautz 1981), or to a l t e r c o n c l u s i o n s of any of the  The  the the  30  Figure  1. Change i n w e i g h t o v e r t i m e by t e m p e r a t u r e a n d density f o r experiment 1. A l l weights have been a d j u s t e d t o a common i n i t i a l w e i g h t u s i n g t h e g r a n d mean s t a r t i n g w e i g h t ( 2 . 3 5 gm) a n d t h e i n d i v i d u a l growth s l o p e s by t i m e i n t e r v a l . -  16  T  0 -I 0  1  1  1  10  20  30 TIME  1  1  1  1  HO  50  60  70  (DAYS)  32  Growth  slopes  (both  Growth  data  (temperature, according effect  was,  as  from  (Duncan's  multiple  the  high  low  the  (Figure  discussion  other were  of  the  with  significant. and  also Of  time.  Time by  pattern  then  were  temperature  by  time,  suggest  that  the  temperature  changed  over  time.  percentage faster  to  a  a  clear by  Further  density  by  indicating  that  density.  The  each  density  influence The  than  peak  thereafter.  and  were  significant.  The  at  These  a  revealed  significant similar  0.0125).  mid-density  10%  rising  follow.  not  12.5°C,  densities  On  interval  than  0.0182  at  is  were  declining  will  higher  the  about  effects  initially,  was  temperature  growing  time  slopes  from  the  on  3-way  by  time  growth  of  interaction  significant. a l l  Since  suggested  level)).  and  interaction  interactions,  density was  low  extreme  (5%  data  interval,  temperature differences  the  two  test  tanks.  were  prediction  not  were  temperature  Similarily,  but  tanks  calculated  slopes averaged  0.0150). (model  ANOVA  temperatures  density  growth  The  slopes  both  other,  range  2);  or  At  by  15°C  significant.  density  of  second  ( T a b l e 4 ) . The  0.0143  each  density  Examination pattern  was  were  different  the  i s at  3-way  (1981)  pooled  i s 15/1000,  value  effects  basis,  That  a  growth  significant.  slopes  in  using  expected,  prediction  Density  time)  analyzed  Tautz  growth  observed  first  Iwama a n d  predictions.  (model the  were  density,  to  calculated model  temperatures)  interactions,  both that  factors one  or  the  takenmore  most  interesting  alone  intervals  were within  was  density  significant, the  growth  by  this period  33  may  be c o n t r i b u t i n g  t o most  of the observed  density  effects.  T a b l e 4. A n a l y s i s o f v a r i a n c e t a b l e s o f g r o w t h s l o p e a g a i n s t treatment f o r experiment 1. P a r t A i n c l u d e s b o t h d e n s i t y a n d temperature e f f e c t s . In p a r t s B a n d C, a n a l y s e s o f t h e 15 a n d 12.5 C d a t a a r e g i v e n . T h e d e g r e s s o f f r e e d o m v a l u e s f o r both the r e s i d u a l and t o t a l terms i n each a n a l y s i s a r e lower than expected since at each temperature, data f r o m one t i m e was l o s t f o r o n e t a n k .  A BOTH TEMPERATURES  12.5  To  C  DF  Temperature Density Time Temp*Density Temp*Time Density*Time Temp*Dens*Time Residual Total  1 2 3 2 3 6 6 22 45  0. 0. 0. 0. 0. 0. 0. 0.  00017606 00000468 00018975 00000227 00000700 00000383 00000337 00000092  0. 0. 0. 0. 0. 0. 0.  Density Time Density*Time Residual Total  2 3 6 •1 1 22  0. 0. 0. 0.  00000444 00011205 00000393 00000090  0.0292 0.0 0.0167  Density Time Density*Time Residual Total  2 3 6 11 22  0.00000225 0.00008380 0.00000327 0.00000094  0.1367 0.0 0.0352  investigate  over  selected  that  the  interval, Data  this,  time  first  Consequently,  MEAN SQUARE  SOURCE  i t was  intervals.  interval  two m o r e  and another  may  ANOVAs  -  decided  time  to  A cursory have  were  been  analyze inspection the  performed,  f o r the remaining  f o r the f i r s t  PROBABILITY  interval  most  one  0 01 52 0 1 072 001 1 0060 0112  -  the  data  indicated crucial.  f o r the  first  three.  were  analyzed  in  a  2-way  34  ANOVA  (temperature,  density).  significant  effects  significant  ( d f = 2,11  density test  affected showed  different density and  (df=1,11  p<.01).  p<.C)1).  growth that  from  As e x p e c t e d ,  during  This  each  other.  indicating  was  found  Mean  that  the  to  also  were  significant  that  Duncan's  significantly  slopes  density  proved  period.  increased  the interaction  of  produced  demonstrated  time  growth  be  effect  clearly  densities  decreased. Unexpectedly,  density  Density  the f i r s t  a l l three  temperature  of  as  temperature  (df=2,11  on g r o w t h  p<.05),  varied  with  temperature. The  remaining  (temperature, temperature  density,  (df=1,33  significant.  therefore,  and  density  density  days.  effects  Neither  suggesting been  (df=4,33 that  different To  suggest  before,  time  3-way  the  (df=2,33  ANOVA  effect  p<.00l)  was n o t s i g n i f i c a n t  (df=2,33  p=.74)  growth  after  of the observed on f i n a l  sizes,  .05<p<.1  clarify  differences  differences.  by  time,  However,  and df=2,33  and  interval.  i n growth  rate,  the f i r s t  14  density  by  or  both  time.  were  nearly  .05<p<.1,respectively)  of temperature  and  time  may  have  densities.  the data,  This  time  occurred during  of density  significant.  the f i r s t  of were  with  at different  effects.  a  steadily  the effects  further  temperature terms  were  in  declined  interaction  temperature, significant  most  analysed As  and  slopes  d i d not a f f e c t  means t h a t  were  time).  p<.00l)  Growth  Surprisingly,  This  3 intervals  was  i t was d e s i r a b l e  justified  since  the  to eliminate interaction  35  Figure  2. Growth s l o p e s a g a i n s t time (mid-point of sampling i n t e r v a l ) f o r e x p e r i m e n t 1. Mean v a l u e s a r e g i v e n . G r o w t h s l o p e s w e r e c a l c u l a t e d a c c o r d i n g t o Iwama a n d Tautz (1981). V e r t i c l e bars are standard errors.  0.005 0  10  20  30  40  MID-POINT OF TIME INTERVAL  50  60  37  Growth  slopes  The  (15°C)  high  ANOVA  (density,  four  time  data  confirming  but  over  which  When  time  was  sizes. lack  similar, level  before,  i n a 2-way  computed  density at  the  indicating  were  most  over a l l  and time had  15°C,  density  density  that  the  during  three  the  by  time  effect  of  effects first  on g r o w t h time  density  the effect  were  by d e n s i t y , t h e  interaction  times*  confirming that effects  affected  Density  of the previous  last  of  significant  were  interval,  effect. h a d no  density (df=2,16  When  effect was  of  p<.001),  was n o t .  (12.5°C) data  from  treatments,  effect  a l l times  density  thought  However,  replicate  was r e a l .  though attained  less  to  term  were  tanks  than  close.  analysed  a  at In  (Table  close,  of  low  The l a c k of  small  suggesting  the trend with  the  4 ) . However  of the r e s u l t s  function  were  for  significant.  i n view  Furthermore,  clear  was  be  were  h a d no e f f e c t  was u n e x p e c t e d  initially  of e f f e c t  both  analysed  Clearly,  time.  and the i n t e r a c t i o n  density  and  times  p<.0l)  the  growth  temperature  that  as  by  the findings  slopes  first  time.  (df=2,5  p=.87),  were  growth.  significant  the interaction  both  on  d u r a t i o n . Time  Growth  a  was  over  (df=2,16  indicated  subdivided  significant  analysed  (Table  However,  determine  were  short  4 ) . The r e s u l t s ,  growth.  changed  To  time)  effects  interaction density  data  periods,  significant affected  temperature  a t 15°C sample that the  density  was  1 5 ° C , and  the  probability  addition,  the  significant  38  interaction at  term  suggested  t h e 1 5 ° C was o c c u r r i n g These  Again, time  density effects (df=2,5  interval  trend  t o that  intervals,  were  were  then  not  p=.l8),  observed  t h e same p r o c e s s  occurred  r e a n a l y z e d by time  interval.  significant  although  during  a similar,  a t 1 5 ° C , was f o u n d .  d e n s i t y h a d no e f f e c t  Proximate  which  here.  (12.5°C)  data  that  (df=2,16  Over  the  first  but less  clear  t h eremaining  3  p=.59).  analysis  Moisture  2-way, n e s t e d  A was  performed  different. both had  significant,  it  was  view  (df=2,17 was  15°C  These  not  revealed (df=2,29  content  that p<.01)  decreased  d e n s i t y increased, so d i d  analyse the  results whether  of  mean  content  were  cases,  and density  temperature  s l o p e s were  fish  the  effect  At 12.5°C  determine  regressions moisture  to  p<.05).  apparent. To  all  of theunusual  At  data  were  as  moisture.  was n o t s i g n i f i c a n t .  decided  separately.  replicates)  Replicates  on p o o l e d  Moisture  As  density,  data.  p<.0CM)  effects.  increased.  interaction  analysis  (df=1,29  temperature  In  (temperature,  f o r the moisture  A subsequent  temperature The  ANOVA  effect  data of  f o r each  density  i t was n o t ,  affected  weight  by sample  a similar  moisture, against  different  not s i g n i f i c a n t l y  significant trend  i n Figure 3a.  weight  for  slopes  temperature  was  however  a r e summarized  calculated  on g r o w t h  linear  percentage  treatments.  different  from  zero.  In  39  Figure  3. Histograms of proximate composition data f o r experiment 1. A-moisture, B - p r o t e i n , C - l i p i d , D-ash. S t i p p l e d b a r s a r e 15 °C d a t a , a n d o p e n b a r s a r e 12.5 °C data. Each f i g u r e i s d i v i d e d i n t o 3 s e c t i o n s . The f i r s t 2 b a r s a r e mean l e v e l s a t e a c h temperature (densities pooled). B a r s 3-5 a r e 15 °C d a t a a t e a c h o f the t h r e e d e n s i t y t r e a t m e n t s . B a r s 6-8 a r e 12.5 °C data a t each of the three d e n s i t y treatments. Vertical bars are standard e r r o r s . W i t h i n each s e c t i o n , common l e t t e r s refer to treatments not s t a t i s t i c a l l y different ( D u n c a n ' s o r S c h e f f e ' s m u l t i p l e r a n g e t e s t s - 5% l e v e l ) .  4-0  75 LU Dd  o  71  a  a  73  i i GO  a  b  a b  •*  69 B  y—  ••i  z  1  CD  LU f—  o  i  ii  >cc:  f—i  68 66  i i  b  a  64 62  b  1  60 /•—^  32  CD  30  LU  28 26  i  ...J  i  a  i  b  24 10  1  CD  GO  8 +  15.0 12.5 (°C) MEANS  1000 600 200  1000 600 200  DENSITY (FISH PER TANK)  41  Protein  Protein (Figure  values  3b).  calculated. p<.05)  not  replicates  Density  (df=2,29  were  levels  decreased  expressed  With  effects  protein  were  with  pooled,  percentage a  2-way  d r y weight ANOVA  p<.00l) and temperature  significant.  increased  as  As  with  with  the  a decrease  decreasing densities.  was  (df=1,29  moisture  data,  i n temperature,  and  The  interaction  term  was  were  analysed separately  significant. The  data  determine 15°C",-  with  i f density  the  Protein  f o r each  effect  levels  however,  decreasing  effects.  a  was  Only  at  density.  was  not  At  ( d f = 2,17  12.5°C,  signficant  trend  in  At  p<.00l).  the effect,  (df=2,11  protein  to  as  p=.24).  levels  with  observed. of sub-sample  were the  that  by t e m p e r a t u r e .  significant  with  calculated middle  different  unlikely  influenced  was  decreasing  protein  significantly appears  data,  regressions  percentage  were  of d e n s i t y  density  Linear  effects  increased  the moisture  Again  temperature  size  from  mean  to test  density zero  affected  fish  at  weights  against  f o r size-dependant 1 5 ° C was  a  slope  obtained. Consequently, i t protein  content.  Lipids  Lipid were  the  effects so.  v a l u e s were protein  were  expressed  data. Without  significant,  as percent pooling  and temperature  of  dry  weights  of r e p l i c a t e s , effects  were  as  density nearly  42  When  replicates  (df=2,29  p<.00l)  and  significant.  The  temperature  decreased  were  moisture  and p r o t e i n .  density  direction  as  presented  from  at  zero.  density  increased. p=.29).  15°C.  Most  As b e f o r e ,  at the high  unimportant  Both  observed  for  at this  in density  separately.  of  15°C,  lipid  with  temperature  results  At  the effect  as  as  decreased.  those  12.5°C,  were  decreased  differences  However,  The  p<.05)  (df=2,17 p<.005), At  density  levels  was  not  moisture  was  in  these  and  the  same  analyses  are  3c.  regressions  effects.  to  of  content  as d e n s i t y  analysed  significant  the trend  i n Figure  Linear related  were  (df=1,11  levels,  not. Lipid  direction  were  effects  (df=1,29  temperature-related  as d e n s i t y  significant  was  in  temperatures  decreasing  protein  temperature  opposite  effects  the  and i n c r e a s e d  investigate  response,  pooled,  interaction  patterns  To  were  were  calculated  regressions there  was  temperature.  f o r the reasons  to  produced  investigate slopes  not  one  exception  -  This  occurrence  was  described  size-  different  the  middle  considered  earlier.  Ash  There  were  temperatures no  trends  content  no d e n s i t y  were  analysed  i n the data.  was  temperature.  relatively Linear  effects  on a s h c o n t e n t ,  together,  It therefore insensitive  regressions  or s e p a r a t e l y .  appeared  that  to the e f f e c t s  were  either There  when were  whole-body ash of density  not c a l c u l a t e d .  and  43  Cortisol  To  increase  analysed  duplicates  were  insufficient  weighting  of  produced to  the  There  w e r e no  effects  were  the  low  temperature.  significant.  These data  Because and a  this  was  number of  made. the  the not  Weight  of  there  length  the  was  was  trend  are  summarized  again  this  Mann-Whitney  significant  significant  a priori  with  justification  was  density were  was  at not  temperature,  transformations U-test  when  values  trend  for  the  no  higher  were h e t e r o g e n e o u s of  only  term  trends  5..  any  that  temperature  in Table  by  so  analysis.  no to  volumes  inappropriate  replicates  however,  t e s t s produced  little  or  of  tested,  comparisons  were  differences 1-tailed for  its  in  a  with  tests, use.  relations  First,  calculated for  weight  mentioned,  Some w e r e  Weight-length procedure.  As  corrected  i n the  was one  plasma  avoid  importantly  a  i n which  or  temperature,  was  variances  2-tailed test.  however  and  non-parametric  None  entered  by  sample  were p o o l e d  ANOVA. The  reanalysed  There  results,  either density  nested  observed,  distinguishable.  were c a s e s  duplicates  s a m p l e was  in a  When  there  plasma  d u p l i c a t i o n . To  e f f e c t s of  were a n a l y s e d  significant.  enable  per  each  questionable  results,  C o r t i s o l value  data  precision,  i n d u p l i c a t e . However,  the  one  assay  relations a  were  examined  f u n c t i o n a l , geometric the  relationship.  natural  log  Secondly,  (In) using  mean  length, this  (G.M.)  two  step  regression  natural  log  regression,  (ln) a  44  Table  5.  Summary  significant  of  effects  Cortisol data results. due treatment. Values  There  were  are  no  given i n  ng/ml.  fish/tank replicate '  1000  600  1  2  200  1  2  1  15.0  C.  n mean S.E.  12 10.8 2.88  13 19.8 2.77  12 14.4 2.88  14 16.0 2.67  16 12.9 2.50  15 22.9 2.58  12.5  C.  n mean S.E.  15 19.6 2.58  16 27.6 2.50  15 22.7 2.58  15 12.3 2.58  15 16.1 2.58  16 24.7 2.50  condition  factor  of  was  one,  equation  created.  (1973,  1975).  I t was  since  different  "customized" This  populations  Small  errors  equation,  especially  trends  lead  can  As tank),  described were  experiment. those  A  5  where  with  weight times  have  customized variable  parts  of  a  exponent,  b,  equation length  condition can  with  value Ricker  weight a  and  length  throughout  data  the  produce  size.  the  data  problems  had  existed,  affected.  analyses,  the  Such  pairs of  indicated  However,  affected  (50  course  of  strongly other  with  interpretation.  feeder  not  a  in condition trends  in  earlier, at  length  p r e l i m i n a r y overview  were  consistency  errors  collected  tanks  relations  were  to  fish  data,  i s p r e f e r r e d by  have  certain  the  curvi1inearities  to  of  in  artificial  the  technique  important  relations.  to  that  weight to  tanks,  per the in  length  maintain 4 and  12,  against  ln  excluded. The  weight  G.M.  functional  produced ln  Wt.  =  the  regression  following  -5.017  +  3.269  of  equation: In  L.  ln  length  45  When  antilogged, the equation condition  which  = weight/(.00662437  i s the condition Using  from  factor  this  equation,  presented  although  in  3  50 c o n d i t i o n v a l u e s  data  were  some  * length '  2  6  9  ),  equation.  the l e n g t h weight  analyses  becomes:  from  each  performed  of  the  tank.  on d a t a  comparisons  calculated  The  with they  were  statistical  replicates were  pooled  significantly  different.  Condition  factors  Condition nested  factor  ANOVA  Replicates  significance.  were  similar  effects p<.005)  the two  To  time  observed  was n o t a l w a y s  homogeneous  groups  and the  indicated  that  to  temperature  by  low  that density  was  3-way,  replicates). on  close  caused the  replicates  were  i n main  effects  and  interactions  i n growth  slope  data.  Temperature  density  (df=2,2499  both  p < . 0 0 l ) were  decreasing  were  middle factors  growth not  the  significant.  densities,  time  The  significant,  produced  and  lowest  Duncan's were  i n c o n d i t i o n over slope.  although  test  highest  densities. a t each  The p a t t e r n  for  a  However,  consistent. Scheffe's  and  times.  time,  trends,  However,  which  in  one o r two c a s e s  (df=4,2499  condition  at a l lother  identical  only  to increase with  densities,  than  observed  effects  analysed  different.  overall  not s i g n i f i c a n t .  tended  pattern  first density,  that  identify  patterns  and  Condition  were  appeared  t o those  were  data  significantly  i t  The  temperatures)  (temperature,  were  inspection,  pooled.  (both  test  different time  was  interaction but  was  of  close  46  (p=.09). time,  However,  and  temperature  (df=4/2/2,2499 on  condition  time,  a l l others, by  p<.00l). changed  by d e n s i t y ,  density  Most  over  temperature by  time  importantly,  time.  are presented  Plots  by t i m e , were  by  significant  the e f f e c t s  of c o n d i t i o n  in Figure  density  of  density  factors  over  4.  T a b l e 6. Condition factor data summary b y t e m p e r a t u r e a n d t i m e f o r e x p e r i m e n t 1. C o n d i t i o n s were c a l c u l a t e d from t h e GM f u n c t i o n a l r e g r e s s i o n of natural l o g of length against n a t u r a l l o g o f w e i g h t f r o m s a m p l e s o f 50 l e n g t h s a n d w e i g h t s taken from each tank. In a l l cells, n=50 and S.E. o f t h e mean = 0 . 0 0 9 2 3 .  TEMP  15.0  12.5  DENSITY  1  1 000  0.919  600  32  46  1 .009  1 .030  1 .009  0.985  0.938 0.915  1 .036 1 .071  1.0-61 1 .007  1 .025 1 .030  0.981 1 .005  200  0.930 0.948  1 .057 1 . 1 00  1 .026 1 .071  1.014 1.014  0.938 0.974  1 000  0.941 0.945  1 .046 1 .045  1 .039 1 .036  1 .005 1.017  0.949 0.955  600  0.954 0.959  1 .055 1 . 1 27  1 .023 1 .023  0.986 1.013  0.961 0.959  200  0.949  1 .064  1.010  1.015  0.952  C.  C.  Condition To  factors  effects  interpretation,  (Table were  61  (15°C)  simplify  separately  14  6 ) . At  temperatures  15°C, w i t h  significant  replicates  (df=2,1249  were  analyzed  pooled,  p<.005),  density  condition  47  Figure  4. C o n d i t i o n f a c t o r s a g a i n s t time f o r experiment 1. V e r t i c a l bars are standard e r r o r s . Since temperature e f f e c t s were n o t s i g n i f i c a n t , t e m p e r a t u r e t r e a t m e n t s were p o o l e d . E a c h p o i n t r e p r e s e n t s 200 l e n g t h w e i g h t observat ions.  I.IOT  DAY NUMBER  49  increasing the  high  than  as  density  the  p<.001),  with  P<.001). increased,  Condition  of  density  and  the  followed  conditions  of  time  was  described  by  time  magnitude  of  indicated  significantly significant  pattern  was  time  peak  that lower  (df=4,1249  occurring.  significant  the  the  test  The  (df=8,1249  required  to  peak  decreased.  (12.5°C) the  density that  (df=4,1249  but  the  pattern  the  for  growth  effect for  was  growth  p<.00l),  interaction  P<.001), case  Scheffe's  increased,  exactly  significant The  effect  density  12.5°C,  pattern.  The  had  previously  factors  At  was  the  As  decreased.  treatments  others.  interaction  trend  density  term  was  slope  significant,  slope.  and  was  less  not  The  effect  followed  also  clear  at  of  the  significant  than  and  15°C  the time  expected (df=8,1249  as  had  been  data.  Behavior  Behavior measurement variance with  data scale  assumption  large  sample  heterogeneity pers.  in  check,  some  reanalysed transformed  may  sizes,  for  T. it  ordinal,  not  meet  statistical  F-values  (Dr.  or  are  Kozak, was  decided  they  are  comparisons  which  were  markedly  follows:  tests.  of to  more  A l l  or  if  on  a  homogeneity  of  analysis.  Faculty  since  non-parametric  the  relatively  analyses  using as  frequently  Therefore,  these  nominal  required  problems  comm.).  methods  is often  However,  i n s e n s i t i v e to Forestry, use  UBC,  parametric  powerful.  As  a  heterogeneous  were  observations  were  50  natural It  should  be kept  arbitrary,  were  i n mind t h a t  i n poor  technical  analysed.  the  time of f i l m i n g feeder  the  one o f t h r e e  recorder  films  from tank 4 was d e l e t e d  In a d d i t i o n , d a t a  the  (temperature,  (df=2,514  densities, density density.  pooled  caused  could  since at  problems  had  were  analysed  in  effects  were  significant  range t e s t  i n d i c a t e d two  data  density)  p<.0l).  homogeneous  density  Scheffe's  groups  as  multiple  follows:  and ( i i ) t h e h i g h e s t was  significantly  (i)  the  fish  to  and  temperature Bartlett's  nor test  most the  different  precise  lack  indicated  temperature  was  separately  temperatures  on  lowest  from  and  only  precise  the  low  terms  at  highest  were  grouped  not c o n s i d e r e d  the  lowest  the  middle  density.  the variances  but n o t when  r o b u s t n e s s of the t e s t it  at  that  o f h o m o g e n e i t y was  Next,  least  interaction  when g r o u p e d by d e n s i t y ,  the  2-way ANOVA  a  and m i d d l e d e n s i t i e s . The m i d d l e  S t a t i o n m a i n t e n a n c e was  density,  two  with  activity  When  the  although  hyperactive.  Net  This  problems  f i l m q u a l i t y and o n l y  be  become  t h e u n i t s o f measurement  consistent.  Unfortunately, resulted  +1.1).  log (activity  Neither  significant.  were by  homogeneous temperature.  important  b e c a u s e of  procedure.  decided  to  analyse  the  i n view o f t h e d i f f e r e n t the  t e m p e r a t u r e were s i g n i f i c a n t  other  data effects  for of  each the  v a r i a b l e s measured. At n e i t h e r  density  effects  found.  However,  51  both It  were  was  close  interesting  pattern  of  (Figure  pooling,  a  replicates  5b)  did were  activity  significant. interaction increased  pooled data,  density  per  15  not  To  was  p=.08).  temperatures,  similar  (Figure  the  5a).  a  different  f o r net a c t i v i t y .  ANOVA  (temperature,  significant  the data  were  effects  of  effects.  Without density,  Consequently,  r e a n a l y z e d . As temperature  density  with  the  were  not  ( d f = 2 , 5 4 9 p<.005) a n d t h e  significant.  interaction  subsequently was  Total  total  activity  not s i g n i f i c a n t  that  levels each  .for  each  At  15°C,  the  ( d f = 2,2-49 p < . 0 0 5 ) . When  at the high  activity  data  separately.  activity  indicated  from  effects,  analyzed  significant  interval  lower  revealed  decreased.  different  was  was  both  observed  both  Scheffe's test  significantly  trend  the  untransformed, second  density.  12.5°C df=2,280  data  ( d f = 2 , 5 4 9 p<.05) were  effect  density  and  However,  was  of  that  not produce  temperature  were  density  nested  investigate  data  at  activity  from  as d e n s i t y  To  that  with  total  2-way,  replicates)  were  note  p=.055;  activity  Analysis pattern  to  i n net a c t i v i t y  Total  net  (15°C df=2,233  doubled density  from t o 8.5  the high  than  o t h e r . At  the  units  a t t h e low  density other  12.5°C,  (df=2,299 p=.59),  4.2  the  tank  two  which  the e f f e c t  although  a  had  of  similar  apparent.  examine v a r i a n c e h e t e r o g e n e i t y e f f e c t s ,  that  parametric  test  comparisons  tests were  were  acceptable, 2-tailed,  calculated  for a l ldensity  and  to  confirm  Mann-Whitney  li-  combinations  at  52  Figure  5. E f f e c t o f f i s h d e n s i t y on a c t i v i t y l e v e l s . Part A i s net a c t i v i t y , the t e n d a n c y to m a i n t a i n a fixed position. High values indicate less precise station maintenance. P a r t B, t o t a l a c t i v i t y , i s t h e total d i s t a n c e moved i n a g i v e n t i m e . A l l values are given i n a r b i t r a r y u n i t s per 15 s e c o n d i n t e r v a l .  S2>  1.6T 1.1 + CO  1.0 +  -12.5 ° C •temperatures p o o l e d (± 9 5 % C L . )  0.8  10  B  -+-  -+•  T  8+ •—  >  LU  to  H— L H I—> i — I «=C \ oo —I t -  <£  I— O  6+  ~  z Z>  15.0 C 12.5 °C •temperatures p o o l e d (± 9 5 % C L . ) U  4+  "0  200  400 DENSITY  +-  600 (FISH  800 PER  TANK)  1000  1200  54  each  temperature.  Water  consistent expected  with  On  the  confirmed  had  were  the  oxygen the  those  listed  The  the  fish  models  mg/1.  levels  above.  61  levels  (Table  7).  density were  was  close  to  size,  and  fish  used  in  determining  observed In  were  side.  and  number  adequate.  most  was  of  slightly  p r e d i c t e d oxygen  (conservative)  46  observed  oxygen  7.1  days  concentrations with  considered  lowest  model  on  temperature,  d e c l i n e d to  Apparently,  oxygen  for. Therefore  46  actual  high  determined  expected.  when  densities day  this  that  levels  and  were  in dissolved  accounted  flows  61  levels  pattern  were  results  quality  Oxygen The  The  8.0  the  than  consumption in  this  were  lowest  By  day  calculations,  higher  Errors  mg/1.  expected.  r a t e s on  direction  the were  acceptable. As  expected,  tanks. growth rates was  While rates during  this  fish  the  final  from  Water analysis. calculated metabolite  may  levels be  suspected  i n these  tanks,  there  the  70%  the  greatest.  for  oxygen  last  of  In  addition,  high  density  were  was  no  at  a  high  contributing  when  density  to  differences  experiment  there tanks  of  i n the  in  to  growth  oxygen  non-significant  15°C  reduced  grow  demand tendency  faster  during  weeks. samples The  were  results un-ionized  levels  were  collected  are  on  presented ammonia  well  within  days  in  levels. safe  Table It  levels.  36  and  58  for  7  along  with  is  clear  that  55  T a b l e 7. Water q u a l i t y data f o r experiment 1. Un-ionized a m m o n i a v a l u e s w e r e d e t e r m i n e d f r o m L i a o ( 1 9 7 4 ) u s i n g pH a n d temperature data. Nitrite levels were below detectable l e v e l s ( < 0 . 0 0 5 mg/1). DAY  TANK  TOTAL AMMONIA  UN-1ONI ZED AMMONIA  mg/1  mg/1  mg/1  0.0018 0.0012 0.0022 0.0028 0.0005  5.60 5.80 5.80 5.90 5.90  1 4 7 . 10 INFLOW  0. 1 05 0.069 0. 1 25 0.161 0.030  _  TANK  TOTAL AMMONIA  1 2 3 4 5 6 7 8 9 1 0 1 1 1 2  0.201 0. 1 32 0.045 0. 1 53 0. 1 39 0.044 0.110 0. 154 0.064 0. 194 0. 183 0.041  pH  7.8 7.8 7.8 7.8 7.8  DAY 58  UN-IONIZED AMMONIA  mg/1  TOTAL NITRATE  TOTAL NITRATE  mg/1  mg/1  0.0024 0.0017 0.0006 0.0020 0.0017 0.0006 0.0010 0.0014 0.0009 0.0023 0.0022 0.0006  4.90 4.80 4.90 5.00 5.00 5.00 5.00 5.10 5.10 5.00 5.00 5.20  pH  SPECIFIC CONDUCTANCE umho/cm  7.6 7.7 7.7 7.7 7.6 7.7 7.6 7.6 7.8 7.6 7.7 7.8  211 210 209 209 209 208 210 209 209 21 1 210 210  DISSOLVED OXYGEN mg/1 DAY N o . 46 61  8.8 9.3 10.0 8.8 9.1 10.0 8.5 8.7 9.0 8.0 9.0 9.7  7.1 8.5 9.8 7.8 8.2 9.4 8.6 8.0 8.9 7.6 9.0 10.0  Conclusions  Results  of this  induced  differences  condition  factors  density  related  Cortisol  levels  evidence  of  experiment in  (tertiary  demonstrated  growth,  proximate  responses  in activity  (a  response  treatment  effects.  The  were  to  treatment-  composition,  to stress).  differences primary  clear  Additionally,  detected.  stress)  effect  and  Plasma  showed  of density  no  varied  56  between were  temperatures.  usually  observed  were  usually  demonstrated  As  that  were  Additionally, interactions by  suggested  that  the  water  quality  ammonia time  high  levels,  prove  either  respect  time the  that  when a l l  growth  slopes.  significant.  two  of d e n s i t y  significant to  were  temperature  and  were  most  by  time.  on  growth  the e f f e c t s  Several  important  being  Together  these  were  different  of temperature  varied  time. Consequently,  temperature. time  effects  the trends  at  important  d i d not a t any  significant,  times  as  un-ionized  effects  and  and  most  with  the e f f e c t s  different  over  temperature  time  temperature,  direction  the  15°C,  responses.  compared  were  same  quality  growth  temperature,  t h e low  and  density  density  at  water  expected,  At  of  oxygen  or a l t e r  treatments  high  i n the  Evaluation  dissolved  limiting,  the  significant.  temperature. data,  At  In  interaction  over  time.  growth these  terms  was  analysed  separately  further  significant  analyses, suggested  Therefore,  data  that  were  density  analysed  for  density  effects by  each  time  by  varied interval  grouping. At  the high  significant short  only  duration  conditioning. be  ascribed At  higher  the  temperature, during of  About  to the f i r s t lower  temperature  the f i r s t  the 90%  density  density of  of  four  effect  on  time  was  the d i f f e r e n c e s  time  growth  were  intervals. indicative  in final  weight  The of  could  interval.  temperature, appeared  effects  during  trends  similar  the f i r s t  to those  interval,  but  at the were  57  not  significant  however,  growth  during rates  non-significant, slopes for  in  the  most  time  In  a l l  time.  a  effect,  since as  analysis, protein the  a  by  at  the  At  density  low  density.  greater  density  data  density  was  in ash  lipid As  were  by  Ash  some w e r e  was  A  growth  observed  pattern  initially and  then  not  a  compensates  for  density  revealed  with low,  declined  fish  size  size.  This  effect,  levels ash  was  and  as  a  density factor  observed In  in  and the  in  moisture,  several  analyses,  were  significant,  temperature.  levels was  and  protein  levels  significantly  were  greater,  unaffected. protein  levels  decreased content density  Although  close,  both  entered  content.  and  before,  found.  time  moisture  significant not  were  interactions  lipid  moisture  and  unusual  e f f e c t s were  analysis  and  with  temperature  not  an  duration  temperature,  12.5°C,  significant,  towards  Overall  effect.  temperature.  increased.  composition  high  interval,  analysis  short  but  lower,  15°C,  At  intervals.  the  low  was  second  temperature  high  significantly,  slope  With  further  the  the  composition  lipids,  significantly than  at  treatments  decline  the  significant  necessitating  by  The  effects.  and  the  there  a l l  conditioning  body  density  At  in  growth with  of  temperature  remaining  trend  over  analyses,  peak  thereafter.  Whole  persistent  rates  steadily  suggestive  the  suppressed  density  growth  to  pattern,  or  intervals.  Growth  increased  were  but  middle  that  few  trends  significantly,  was  not  effects of in  increased  the  as  affected. on  proximate  comparisons  moisture,  were  protein  58  and  lipid  higher  data  suggested  similar  at the  temperature.  With  temperatures  differences  to  probabilities patterns  pooled,  i n net a c t i v i t y  attributable  density  while  observed  this  pattern  pattern was a r e a l  (the tendency  not  were  identical.  to maintain  were  Levels  near  temperature, and  were g r e a t e s t The  significance,  consequence of  positions)  close,  a t t h e low d e n s i t y .  the  significant  However, a t e a c h  significant,  were  and  there  effects.  m i d d l e d e n s i t y , and l o w e s t of  r e l a t i o n s h i p s to those  density,  at the  consistency  suggest  and  the  not  that the a  chance  occurrence. Total at  activity  15°C, n o t so a t 1 2 . 5 ° C ) .  findings  in  discussed  .later.  conjunction  No t r e n d s This by  would different  Schreck  densities,  the net a c t i v i t y  fish or  adjustment  (significant  concentrations  that  if  of i n t e r r e n a l  unlikely  were  in  initially activity  The f i r s t view  these will  be  present. stressed  stressed,  a  as d e s c r i b e d  by  hypothesis,  of  of  results  were n o t d i f f e r e n t i a l l y  have o c c u r r e d .  appears  increased  The p o s s i b l e s i g n i f i c a n c e  i n plasma C o r t i s o l  (1981) may  stress  as d e n s i t y  with  i n d i c a t e that  compensatory  no  decreased  that  a l l other  of  results  presented. Condition growth  slope  significantly  f a c t o r data data. with  At  time;  showed both  factors decreasing  trends  temperatures,  the p a t t e r n  g r o w t h s l o p e s . O n l y a t '15°C were condition  similar  being  density  as d e n s i t y  to  those  conditions  identical effects  of  varied  to that for significant,  i n c r e a s e d . A t 12.5°C,  no  59  trend  was  apparent.  temperatures, peaking any  at  In the  higher  time,  condition  a  the  reflected  densities.  From  by  a  was  significant  tendency  these  correlation  the  response  temperatures.  differences  of  was  term  data  towards  i t is clear  between  growth  at  both  delayed that  slope  at and  existed.  indications  similar  interaction  strong  summary,  two  noted,  and  The  of  to  manifestation  not  those  response  rearing  15°C,  stress-induced  associated  although  At  to  with  15°C,  i s reduced  i s delayed.  At  the  12.5°C,  lower  that  is different  clear  significant,  suggesting at  are  metabolic  density.  statistically at  there  density  and  consistent  and  behavioral  the  differences  followed  either  at  the  temperature,  or  trends  magnitude that  its  60 E X P E R I M E N T 2:  STRESS RESPONSES IN  FINGERLINGS  Introduction This and  experiment  stress  examined  the  e f f e c t s of  in juvenile steelhead  Weights  were e x p e c t e d  to  enable  detection  growth d i f f e r e n c e s  consequences Since the  of  the  first  may  density  were  density  first  density, this  r e s u l t s of days  after  density)  be  could  (or  most  to  the  growth  initial  experiment  and  a  test  i t  other  new  weight). and  thus  physiological  density  e f f e c t s of  is  suggested  density  is  the  transfer,  the  important in  a  upon  determines  the  gm  experiment at  s e n s i t i v e , the  experienced  and  first  If  (15  on  stress.  weeks)  transfer  have  management  the  examined.  . that  during  density-induced  few  immediately  of  double  trout  density  magnitude  implications  interpretation  from  the in  of  common  changes  in  change  in  relative not  period  a  sudden  and of  (the  the  c  that  actual  stress  response  both  hatchery  r e s u l t s of  density  experiments. Lastly, time  to  should time.  experiment  determine  experiment pattern  this  i s repeated  suggests  if  examines  the  with  pattern larger  a conditioning  either accelerate  or  changes observed  fish.  changes  growth  over  the  first  in  Since  e f f e c t , sudden  decelerate  in  the density  in  observed changes  growth  over  61  Materials  The groups  experiment of  numerical weight Tank  times  in four On  a  8.  of  the  On  oval per  650  fish  immediately  excess  tanks  third  6  experimental  to  experiment  1980,  about  4 weeks  corresponding to  until were  one  the  similar  to  that  of  at  250  changes  litres.  This  eight-fold  gm/1  ( 1 / 3 .- 3  is  presented  before  rearing  the  start  circular  of  tanks  approximately  about  study.  sudden  basis were  litres  Fish  experiment  volumes  volumes  would  observed was  i n the limited,  used.  the  control,  time  (not  were  treatment,  slopes with  tanks  the the  treatments  second  tank  mean  13.9-16.1).  were  density  of  Initial  similar  2 m  before  number/volume  held  in growth  start  week  effects  volume  that  a  two  40  gm/1  were  fed  began,  when  given.  the or  the  °C.  to  48  had  tank,  12.5  of  an  design  There  a  of  was  one  500  represented  this  in this  or  at  examine  number  250  held  pattern  the  either  Replicated  (range  and  treatment,  decided  gm,  tanks  rations  In  to  at  tank).  from  initially  litres.  0.61  per  transferred  prior  three  The  1980.  reared  fish  and  6,  were  weight/volume basis)  were  basis  13,  December  fish  rations  To  on  ±  groups  used  November the  the  15.1  densities).  study,  to  reduced  density  Methods  800  adjusted  A l l fish  histories.  was  or  weight/volume  standard  Table  (200  a l l tanks were  started  juveniles  densities--  volumes  range.  in  steelhead  over  resulted  was  and  were be  density  numerical  In  opposite  showed  and  a  doubled  not  first  in  one  a  density  treatment,  i n volume  to  500  was  In  the  done.  unchanged.  It  adjusted until  evidence  experiment. the  on  of  a  was the  decline,  Unfortunately,  experimental  design  62  could  not  (density) slopes. showing  be  balanced.  was e x p e c t e d These  to alter  changes  evidence  Changing  were  of growth  the a v a i l a b l e  the rate expected  differences  of  per  fish  change  in  density  ranges not  t o volume  changes.  over prior  space  growth  T a b l e 8. D e s i g n o f e x p e r i m e n t 2. Tank volumes were changed o n d a y 32 ( d e n o t e d b y t h e s e p a r a t i o n i n t h e t a b l e ) . E x p e c t e d maximum a n d final densities were calculated according to Iwama a n d T a u t z ( 1 9 8 1 ) u s i n g T / 1 0 0 0 .  TNK  1 2 3 4 5 6 7 8 9 1 0 1 1 1 2  FIRST DENSITY INITIAL MAX f / 1 gm/1 gm/1  FIRST NUMBER VOLUME FISH litres  200 800 200 800 200 800 200 800 200 800 200 800  All  250 250 250 250 500 500 500 500 500 500 500 500  fish  0.8 3.2 0.8 3.2 0.4 1 .6 0.4 1 .6 0.4 1 .6 0.4 1 .6  were  reared  10L:14D.  Lights  off  1730 h o u r s .  an  at  were  were  the previous The  different  design  18.8 75.2 18.8 75.2 9.4 37.6 9.4 .37.6 9.4 37.6 9.4 37.6  at  500 500 500 500 500 500 500 500 250 250 250 250  A l l  tanks  growth  conservative.  '  12.5°C  automatically  optimistic projected  estimates for  1 2 48 1 2 48 6 24 6 24 6 24 6 24  SECOND VOLUME litres  AVE f/1  0.4 1 .6 0.4 1 .6 0.4 1 .6 0.4 1 .6 0.8 3.2 0.8 3.2  0.6 2.4 0.6 2.4 0.4 1 .6 0.4 1 .6 0.6 2.4 0.6 2.4  9.4 37.6 9.4 37.6 9.4 37.6 9.4 37.6 18.8 75.2 18.8 75.2  Photoperiod  switched  received rate  SECOND DENSITY - I N I T I A L - FINAL f/1 gm/1 gm/1  was  Feeding  1 2 49 12 49 12 49 12 49 24 98 24 98  was  set  at  on a t 0730 h o u r s a n d  flows  o f 25 1 / m i n .  used, rates  maximum were  Since  density  c a l c u l a t e d as  experiment. of  the  analyses  be  experiment run  necessitated  o n t h e same d a t a ,  that  b u t on  several different  63  groupings. manner  Part  as  of the  the  experiment  first  was  experiment.  analyzed  in  Details will  the  same  be g i v e n  where  appropr i a t e . Total 53.  weights  Length  53.  and weight  During  plotted  were  the  m e a s u r e d on d a y s  data  course  against  of  time.  anticipated  changes  The  trend  was  Plasma  samples  After  two  were  10,  on d a y s  the  i n growth  first  pattern  17, 3 1 , 4 6 ,  3,  the experiment,  At  detected  taken  1,  10, 3 1 , 4 6 , a n d  growth  slopes  indications  tank  were  were  of  volumes, were  on d a y 3 1 , a n d c h a n g e s  and  the  altered.  made  on d a y  32.  56.  collected  monitored  Water  samples on  days  of  f o r proximate  were  etc.  for Cortisol  the  recorded.  collected  same  days.  41  were  collected  on  day  d a y 58, s a m p l e s  were  Dissolved  a n d 49, u s i n g  for analysis Behavioral  were  and flows  on  composition.  Mortalities  Temperatures  starvation,  on two d a y s ,  were  a n a l y s i s were  recorded checked  oxygen  Winkler  of  pH,  every  2-3  reagents.  metabolites,  observations daily  levels  but  were  were  not rare.  days.  Results  Growth  During due  course  of t h i s  to t e c h n i c a l d i f f i c u l t i e s .  feeder data  the  problems  for that  resulted  in  i n tank  period. the  During  some  the f i r s t  2 r e s u l t e d i n the loss  More  loss  experiment  of  p e r s i s t e n t feeder growth  slope  data time  were  interval,  of growth  problems  information  lost  slope  i n tank  5  f o r three  64  intervals.  Changes  Figure  6.  Growth  slopes  To  both  most  times  were  analyzed  treatment. peak  growth  growth trend  from  t o be s i g n i f i c a n t . time,  however, that  slopes  Growth (Table  8,  0.4  (df=4,l6  (about  effects  On a  0.33  to  The d a t a were  i n the high  not  density  o f t h e low d e n s i t y  treatment  reached  f o r a more  rapid  density.  the interaction p=.11).  a  higher  decline i a F o r such term  a  would  The  effect  p<.05) a n d t h e p a t t e r n  closely  expected.  (average  densities)  rates  were  last  col.).  treatments.  volume  growth  treatments  densities).  fish  at the high  on  experiment.  t o 1.6  I t was n o t ( d f = 4 , 1 6  was  in  s e p a r a t e l y . On  these  a t 90% o f t h e r a t e  analysed  based  into  on a v e r a g e  Accordingly there  d e f i n e d by one o f two n u m e r i c a l  volume  basis,  However,  than  given  density  Density  was a t r e n d  time  are  analyzed  hatchery  t h e low d e n s i t y there  with  were  t o be d e t e c t a b l e s t a t i s t i c a l l y ,  Growth  and  slope,  constant  ANOVA.  p=.11).  time  i n the f i r s t  maximum  t o grow  Although  tested  ranged  2-way  (df=1,16  slope  followed  each  a  appeared  of  a n d number/volume  density  in  over  treatments  (5,6,7,8)  conventional  significant treatment  effects  of the range  basis,  1.3  density  tanks  a weight/volume  fish/litre  of  the  the control  spanned  have  i n constant  examine  slopes,  i n adjusted weights  densities  I t was n o t p o s s i b l e a n ANOVA  since  they  were  to enter  density  groups  s i x treatments,  a n d one o f both  c o v a r i e d almost  fish  three number  perfectly.  65  Figure  6. C h a n g e i n w e i g h t w i t h t i m e f o r e x p e r i m e n t 2. w e i g h t s h a v e b e e n a d j u s t e d t o a common i n i t i a l size u s i n g a n i n i t i a l w e i g h t o f 15 g r a m s a n d t h e g r o w t h s l o p e s by t i m e interval.  A l l  35 T  TIME (DAYS)  67  Following volume  t h e work  e f f e c t s would  when  volumes  due  to  were  density  (average  increased  changes. time)  terms  fish  in  200 f i s h which  interaction time,  changes.  initially, between  (constant  density)  could  rising  times  were  produced  3  examined,  patterns  (Figure  that  have  to  a  been  with  peak,  of s u f f i c i e n t  over  This  groups. time  probably  ANOVA  although that  and then  the tanks 800  different.  The  changed  over  o f sudden  density  expected  --  declining.  magnitude  density  containing  density  was a s  and the  the pattern  only  were  a function  time  time  average  and those  of  When  i n a 2-way  As  doubled,  the effect  pattern  homogeneous  7).  were  Therefore, were  density,  indicated  that  any e f f e c t s  entered  decreased,  test  The o v e r a l l  that  9 ) . Average  slope  i t was a s s u m e d  Discussion).  a l l significant.  densities  this  were  Scheffe's  suggested  however  (General  The d a t a  growth  not consistent.  (1977)  i t was a s s u m e d  (Table  were  overall  containing  be m i n i m a l  changed,  density,  interaction  was  of L i and Brocksen  that  low  Differences  Scheffe's  test  i n d i v i d u a l treatments  d i d not always reflected  the  follow  this  sudden  were trend  changes i n  density.  Growth  before  To  density  examine  therefore  were  covering  an  of  800 f i s h ,  entered  growth  weight  intervals  in  changes  densities  analyzed 8-fold  2-way  before  were  high ANOVA.  range or  tank  changed,  separately.  density  and e i t h e r a  diffences  There  (Table low  Density  volumes,  the were  first four  and three  groups  8, c o l . 4 ) , e i t h e r  volumes.  The  e f f e c t s were  data  200 were  significant  68  Figure  7. Growth s l o p e s a g a i n s t time (mid-point of sampling i n t e r v a l ) f o r e x p e r i m e n t 2. Growth s l o p e s were c a l c u l a t e d a c c o r d i n g t o Iwama a n d T a u t z (1981). V e r t i c a l bars are standard errors.  LI  0.020T  200 fish 200 fish 200 fish  constant low density high to low density low to high density  800 fish 800 fish 800 fish  constant low density high to low density low to high density  0.015 + D_ O  I  OO  CD CD  0.010+  0.005-  0  10  20  30  40  MID-POINT OF TIME INTERVAL  50  60  70  T a b l e 9. Analysis of variance of growth slope data for e x p e r i m e n t 2. Average d e n s i t y t r e a t m e n t s were e n t e r e d into the a n a l y s i s ( T a b l e 8, l a s t column). Tests are considered significant if p < 0.05.  Density Time Density*Time Residual Total  (df=3,33 lowest  (3.2  5 4 20 26 55  p<.05). With  three  slope.  groups,  However,  f/1),  effect.  the  The means  between  the  i n t e r a c t i o n term,  p=. 1 0 ) ,  suggesting  inherent  in  the  previous  the  significant  Growth  after density examine times 8,  X d f =1,21 growth in  8)  (df=3,21  p<.005). slope  growth  with  rates  As  i t may  reduction (1.6  This  f/1)  times  have  interaction  been  on  and  a l l  a  were  was  the  the  6  growth highest  p<.00l),  different.  close  change  the  threshold  (df=2,33  entered  significant  within  i n mean  suggests  significant  analysis  changes  (df=6,33 in  density  treatments  that  effect.  the  after  sudden  separately.  were  as  before,  the  lower  the  pattern  numerical  new  The  changes,  density  Density  were  in density.  density  Four  compared.  p<.05),  increases at  not  examined  col.  significant  were  density,  changes  growth were  highest  three  though that  caused  (Table  of  in  slight  marked.  of  each  a  third  time  The  two  was  was  0.00483 0.0 0.00080  increase  e f f e c t s of  the  last  each  decline  PROBABILITY  0.00000637 0.00005694 0.00000731 0.00000144  there  and  To  MEAN SQUARE  DF  SOURCE  showed more  groups  effects  effects a  of  were time  reduction  rapid  d e n s i t i e s was  the  in  decline  especially  71  apparent. Did extent that  The  the changes  than the  expected  were  that  growth  changes  density  could  were  were  regressions various slope  less  be  for  last  changes,  growth.  with  three  when  than  expected  intervals  whether  expected  volumes slope  from  were n o t over  changes.  were  and compared  densities  test  that  i n growth  average  i t i s apparent  To  i n which  Changes  Recalling  time  Linear  calculated for  using  equality  of  tests. ' the controls  analysis,  However,  i t appeared  accelerated  When  different.  slopes  were  not  different  of d e c l i n e  density.  missing,  and as expected  were  the rate  a t the lower  the  low d e n s i t y  with  increased  densities  that  compared,  in  from  (p=.09).  growth  slopes  Unfortunately, data  reducing  the  the  from  sensitivity  of  comparisons.  compared  were  were  their  of the c o n t r o l s  subsequent  were  volume  tanks  combinations,  earlier  one  those  alone?  b u t n o t when  or greater  compared  the  treatment  First,  was  than  to a greater  significant  a l l times,  as c o n t r o l s .  therefore  were  (p=.54).  slopes  density  had a l t e r e d  alone,  used  growth  of  and a f t e r  changes  effects  changed  over  not s i g n i f i c a n t  alter  effects  before  the density  was  on t h e b a s i s  compared  analyzed  term  in density  interaction  treatments were  interaction  a t time  t h e low d e n s i t y (densities  i n growth  sudden  density  there  slope  treatment  was  a  and  trend which  in fact,  constant  in  not  volumes  had  equal  significantly  towards had  volume)  which  i . e . both  s l o p e s were  i n the group  reduction,  (200 f i s h ,  decreased,  of comparison),  However,  decline  controls  a less  undergone  i n the f i r s t  steep the  interval  72  following  density  When  the  treatment  in  changes,  same c o n t r o l s which  significant  (p<.05).  prediction,  i . e . an  growth two  slopes  with  different  density  density  the  appeared  to  basis  density  In slopes the  affect  when  densities  there  would  be  a  growth  Proximate  decline  been  of  that  none  difference  of  in  fish  one  the  high  of  was  between  the  absolute  the  earlier  growth  over  this  (increasing  the  accustomed  than  at  d i f f e r e n t . In  the  had  no  to  would  both,  same  effect,  were  consistent than  one  density,  expect  on  the  numerical  density,  were  however,  trends  were  in  the  it  decreased (although controls  would  seem  improbable  ( i . e . volumes  increased),  non-significant) that  had  trend  for  continuously  density.  analysis  Statistical groupings.  more  the  rate  the  direction.  conditioning  experienced  had  comparison  that  faster  fish  with  in  per  were  consistent  unlikely  space  density  differences  comparison  since  significant  growth  significantly  If  is  low  alone.  neither  expected  this  important,  the  in  increased.  the  slope  was  (2-fold)  it  with  halved,  Although  Decreasing  after  of  pattern  was  there  range.  density)  The  increase  actually  compared  were  densities,  were  were  rates  volumes  time.  difference  analyses  growth  In  analyses  a l l analyses,  were weight  performed was  used  on as  average a  density  covariate.  73  Moisture  The  r e s u l t s of a  covariate Figure  effect  f o r the 6 average  density  As of  p<.001), weight.  the  covariate This  for  that  other. observed  suggested  that  was  were  was a l s o  regression  lines  However,  since  t h e mean  density  effect  i s likely  would  by  the  (df=1,49 by  i t  (df=5,49  was  i s  not  likely  disappear  were  the that  as  their  and crossed  weights  fish  interaction  significant  approached  sample  (df=5,49  affected  of weight  Consequently, treatments  a  so d i d m o i s t u r e . The  defined  the effect  as  are presented i n  significant  levels  term,  weight  significant  increased,  density,  e f f e c t s between  - density  were  moisture  of slope  with  treatments  weight,  a l l treatments.  significant covariate  density  with  ANOVA  density  covariate,  The e q u a l i t y  p<.005).  of  average  indicating  the  same  nested  8a. The e f f e c t s  p<.00l).  of  1-way  each  close, the  real.  Protein  The  r e s u l t s o f t h e 1-way,  covariate, Protein  produced  levels  significant  tended  density  to increase  were  c o l l e c t e d , one o f t h e high, d e n s i t y  other the  f / 1 , even high  time  similar  though  density  which  had lower  densities,  effects average  density,  was  had a d e n s i t y levels.  suggests  weight  (df=5,49  treatments  density  protein  this  with  8 b ) . At the time  i t s average  treatment,  of sampling, average  (Figure  with  pattern  3.2  irregular  ANOVA  the  of  was  nested  a  p<.05). although  that  samples  had a  density  2.4 of  Since  that  as  f / 1 . The 1.6  f/1 at  both  had  the-metabolic  74  Figure  8. Histograms of proximate c o m p o s i t i o n data f o r e x p e r i m e n t 2. A - m o i s t u r e , B - p r o t e i n , C - l i p i d , D-ash S t i p p l e d b a r s a r e t r e a t m e n t s c o n t a i n i n g 200 f i s h . E r r o r bars are included. B a r s b e a r i n g common s m a l l c a s e l e t t e r s a r e n o t s t a t i s t i c a l l y d i f f e r e n t (Duncan' or S c h e f f e ' s m u l t i p l e r a n g e t e s t s - 5% l e v e l ) . Uppe case l e t t e r s a t the base of the bottom graph i n d i c a t e density treatments (e.g. H-L means i n i t i a l l y h i g h d e n s i t y , then d e c r e a s e d ) .  00  ASH •<Z DRY WEIGHT) ID  -4-  PROTEIN % ( DRY WEIGHT) CD  cn  cn  at tr  a  MOISTURE  76  consequences densities densities the  increase,  that  a greater  tanks.  This  stress  high  may  terms  The  both  were  pattern  on p r o t e i n  may  i n d i c a t i v e of greater  within  high  density  levels  tanks  quickly  when  quickly  when  the covariate  significant in  densities, within  effect be  appear  disappear  moisture,  test  p<.005). at  composition  also  As w i t h  slopes  and df=5,49  suggested had  of  on body and  a r e reduced.  equality  p<.05  of  of density  than  (df=1,49  covariate  tank  size  i n the  within  analysis  (Figure  slopes  variations  low  differences  than  and  density in levels  low  density  tanks.  Lipids  The clear.  results  This  of  the  lipid  was d u e t o a h i g h e r  degree  of  8c) were  variability  less  between  replicates. In the the  nested  r e p l i c a t e s term effects  (df=5,49 clear, the  t h e 1-way  high  of  was  both  p=.09; d f = 1 , 4 9 however, density  all  others.  high  densities.  that  ANOVA  significant  weight  as a covariate,  (df=6,49  p<.01),  density  and the c o v a r i a t e  p<.09).  Upon  differences  treatment,  There  with  i n which  was a t r e n d  visual d i d exist volumes  towards  were  although nearly  inspection especially were  a reduction  only  i t  so was  between  halved, in lipids  and at  77  Ash  As  with  between  the  previous  replicates  were  the  lipid  analysis,  was  not s i g n i f i c a n t .  analysis  greater  than  the probability There  were  for  lipids,  between  value  differences  treatments.  Unlike  for the density  no t r e n d s  in  the  data  effect (Figure  8d).  Cortisol  Eight  plasma  duplicate. In  This  a l l cases,  was,  Cortisol  There time it  was  the data  difficult  weight  were  Data density those  per  in tank.  and  there  tank  tanks.  No  levels was  factor.  (within  1  trends  were  made  and sampling  variation  correction  plots  time.  as  sample  large  making  Since  sample  min), the effect in Cortisol  with  was fish  apparent.  were  described  analysed  indicated  2  in a  1-way,  of  average  The r e p l i c a t e s a  nested  replicates).  previously analyses  effects  concentrations. test  weight  increased Cortisol  close  between  treatments,  no  assayed  analysed  statisticaly,  sample  within a  were  constant  both  towards  apply  times  were  determinations  successfully  analyzed  However,  to  tank  to pool d u p l i c a t e s .  were  trend  each  i n 16 C o r t i s o l  values .against  progressed.  probably  from  d u p l i c a t e s were  a  processing  were  resulted  t h e r e f o r e , no n e e d Before  of  samples  marked  term  (6  The t r e a t m e n t  (Table density was  ANOVA  8, on  last  of  groups  col.).  plasma  significant.  heterogeneity  average were There  Cortisol Eartlett's  variance  between  78  T a b l e 10. Summary of C o r t i s o l data. T h e r e was no e v i d e n c e of s i g n i f i c a n t differences between t r e a t m e n t s . Values are g i v e n i n n g / m l . S a m p l e s s i z e s i n a l l c e l l s w e r e 16. S t a n d a r d e r r o r s ( o f means) were 0.71. fish/tank replicate '  200 1  h i g h t o low d e n s i t y constant density low t o h i g h d e n s i t y  treatments. this  Several  problem,  parametric  none  comparisons  replicates  pooled.  comparisons  indicated  were  15.1 12.3 12.0  no  patterns  Only  in  considered  unimportant.  the  that  linear  length, were  data  A natural =  15  to  eliminate  Consequently,  on  the  (Table  non-  data  Mann-Whitney  occurences  from  functional  of  time  with LJ-test  However,  there  10)  suggesting  and  were  l o g of weight equation  length-weight experiment.  relationship intervals  Consequently,  GM  the  i n the f i r s t  regression  f o r i n the  . 9 3 ) . The  tested  differences.  data  chance  treatment  outlined  excluded.  accounted  the  12.4 12.1 15.4  the  therefore  relations  Statistical same a s  of  the  possibly  were  performed  4  2  11.4 14.9 12.3  successful.  significant  were  length  were were  differences  Weight  11.3 12.6 12.5  transformations  but  800 1  2  where 2650  between feeder of  3000  In  data  was  the  calculating  l n weight problems data  and l n  occurred pairs  were  equation. r e g r e s s i o n of natural was  calculated.  of the l i n e  was:  The  l o g of l e n g t h a g a i n s t data  f i t was  good  ( r  2  79  ln  Wt.  Rearranged  = -4.317 and  antilogged,  condition which  i s the  + 2.956 * l n L.  factor  working  the  equation  becomes:  = weight/(0.0133398  * length ' 2  3  5  6  ),  equation.  T a b l e 11. C o n d i t i o n f a c t o r d a t a summary. Values are given for treatment g r o u p s on t h e b a s i s o f a v e r a g e d e n s i t y ( s e e Table 8). Densities were changed on d a y 32 a s d e s c r i b e d in the methods s e c t i o n . R e p l i c a t e s were n o t significantly d i f f e r e n t and were therefore pooled. L e t t e r s i n column 2 refer to r e l a t i v e d e n s i t y changes. F o r e x a m p l e , H-L, means i n i t i a l d e n s i t y was h i g h , a n d t h e n on d a y 32 i t was halved,.  AVE f/1  DENSITY TREAT.  0.4 0.6 0.6 1 .6 2.4 2.4  L-L H-L L-H L-L H-L L-H  factor  The  (df=5,2499), terms  were  small, lowest  to  was  high  different.  53  0 .981 0 .996 0 .997 1 .009 1 .010 0 .996  n  S.E.  1 .016 1 .030 0 .983 1 .026 1 .041 1 .024  50 1 00 1 00 1 00 50 100  0.0096 0.0068 0.0068 0.0068 0.0096 0.0068  were  analysed  data data  density, time  (Table  time),  treatment found  volume). Notably,  (200  i n one Only this  of  replicates  and  (p<.00l). the  11)  with  (df=4,2499)  surprisingly,  density  46  1.017 1.017 1.014 1.015 1 .024 1 .025  .985 .995 .010 .980 .014 .991  significant  and  highest  0 0 1 0 1 0  condition  (average  DAY 31  10  0 .989 1 .003 0 .984 0 .988 1 .009 0 .988  Condition  ANOVA  3  the  The  lowest fish, the  these  in  constant  treatments was  i n the  was  2-way  Density  (df=20,2499)  mean  mean v a l u e  treatments  pattern  pooled.  interaction  range  in a  values found  volume),  in  was the  while  the  c o n t a i n i n g 800  (low  were  significantly  opposite  direction  80  to  the  one  pattern  with  The as  had  the the  observed  first  the  of  variables was  first  within  the  time  other  d i d not  i n the  the  experiment.  first  attributable  treatments  follow  before  other  to  that  experiment.  experiment,  f o l l o w e d each  There  the  sudden  no  clear  tested. i n growth  slopes  However,  during  volumes  closely.  was  were  The  changes  adjusted,  significant in  density.  quality  Oxygen times  on  between  levels day  times  corresponds maximally dynamic oxygen  were  the  greatest.  In  density 1000  (Table  time due  i t  to  day  measures  this  of  experiment a l l tanks,  when levels  growth  should  and  specific  that  single-  adequate  collected  the  be  c o n s t r a i n e d by  view  demand  above  interval  levels  were  three  Differences  time  was  the  were  oxygen were  this  activity,  levels  measures  measured  hours.  oxygen  supports  oxygen  Additional  when  that  were  1500  Since  feeding,  is unlikely  tanks  and  12).  of  Furthermore,  intended.  of  small  depressed  levels.  high  between  the  action,  purpose  i n the  41,  to  point-in-time  end  case  part  interaction  Water  density  pattern with  been  two  i n the  should minimum  for  the  near  the  have  been  acceptable  levels. The  results  collected was  on  of  day  a c c e p t a b l e and  stress  response.  guideline unlikely  maximum that,  the  41  laboratory  (Table  unlikely  12) to  analysis  also have  indicate  in  the  in  the  remaining  were  General of  samples  water  either  levels  days  water  that  affected  U n - i o n i z e d ammonia discussed  of  growth  or  below  the  well  Methods. the  quality  It  was  experiment,  Table 12. Water q u a l i t y data summary f o r e x p e r i m e n t 2. To investigate variations during the time o f d a y when o x y g e n demand i s g r e a t e s t , o x y g e n l e v e l s were d e t e r m i n e d a t t h r e e t i m e s on d a y 4 1 . W a t e r s a m p l e s f o r l a b o r a t o r y analysis were c o l l e c t e d t h e same d a y . Oxygen d a t a were again collected on day 49. Nitrite levels were below detectable levels ( < 0 . 0 0 5 mg/1). Un-ionized ammonia l e v e l s were determined from L i a o (1974) . D  TANK  2 4 6 8 10 12  TIME hrs.  10: 10. 1 0 1 1 1 1 1 1  OXYGEN  14 44 44 16 1 6 16  TIME hrs.  8.35 8.48 7.75 7.10 7.00 7.60  13:00 1 3:00 1 3:00 1 3:00 1 3:00 13:00  TOTAL UN-IONIZED TOTAL AMMONIA AMMONIA NITRATE  mg/1  1 2 3 4 c O  6 8 1 0 12  0.260  -  4!  Y  mg/1  DAY  TANK  A  mg/1  0.0018  -  OXYGEN  -  TIME hrs.  8.50 8.20 7.80 7.10 7.30 8.30  1 5:22 15:25 1 5:29 15:20 15:15 15:17  -  -  7.5  219  -  -  9.75  -  9.90  7.5  220  1 .5  0.464 0.470 0.414 0.265  0.0032 0.0033 0.0024 0.0019  5.65 5.70 5.70 5.75  7.5 7.5 7.4 7.5  225 224 221 219  4.1 2.7 3.5 1 .4  conclusion.  49  -  1 .5  5.70  increased  8.60 8.50 7.40 7.00 7.60 7.80  SPECIFIC DISSOLVED CONDUCT T U R B I D I T Y OXYGEN umho/cm J.T.U. mg/1  pH  0.0021  levels  mg/1  DAY  0.306  metabolite  OXYGEN  41  mg/1  5.65  mg/1  sufficiently  to  -  —  alter  this  82  Conclusions  The of  the  results  previous  stress-related plasma  of  this  experiment  there  response  density.  As  no  evidence  slopes  and  proximate  to  levels, of  densities.  Condition factor  decreased  body  data.  This  their with  was  period  of  density  tended basis  to  the  a  conditioning  of  quality  not  artifact  acclimation  on  did  Density  expected  alter  the  effects  only  the  time  lowest  In  increasing  densities  growth  on  indicator,  with  at  further  stress,  repeated  and  i f  these growth  in  these  conditioned  doubt  that  sudden  more  the  to  trend  after  a  changes  in  than  supports  response.  high  and  Additionally,  oxygen  growth  indicators,  stress  was  response  growth  both  level  densities,  This  that  stress  become  model.  a  experiment,  curvilinear  removes  rearing  growth  1.6  different.  fish  of  expected  the  idea  I n s p e c t i o n of metabolite  of the  levels  results. on  and  the  alone.  indicate  p a t t e r n over  compared,  to  influence  data  0.4  of  The  those  first  inconclusive,  experiment  that  than  evidence  However,  associated  It also  the  density  influence  •containing  idea  environment. an  were  contradictory.  the  clear  increased  results  first  level  tertiary  is truly  i n the  i n the  effects.  suggest  condition  somewhat  rearing time  water  that  supports  primary  composition,  results  observed  a  density  produced  pattern  was  However,  showed  were  less  experiment.  corticosteroid  results  were  treatments  were  not  fish/litre  observed  were  when  compared;  treatments  however,  o c c u r r e d . When  a l l 6  and  highest densities  one  with  mid-way  of  the  similar through  treatments  average the  experiment  the were were  densities, produced  83  lower  overall  decreased. after than  a  growth  This  period  all  comparisons  to  changes  than  suggests  of  increasing  rates  space  growth  in  that  acclimation  the  has  after  rates  density  those  a  in  which  densities  decreasing  the  a  effect  greater  space  responded  (although  3  in of  the 4  per  on  similar acclimation  the  fish  growth  period.  expected  of  were  In  direction  tests  were  not  significant) . Changes followed  in  the  whole same  the  data  moisture  and  protein  there  was  effects  on  ash  average  both  section, fish  stress.  no  in  the  c l e a r . As tended  density  reduced  on  lipid  trends  in plasma  at  increased,  Although  content high  density  experiments.  density  increase.  levels  detected.  average  previous  average to  were  differences  density  the  15-30  condition  of  as  with  were  found,  densities.  corticosteroids  no  No  associated  density.  Significant with  of  content  were  less  levels  effects  There with  were  evidence  composition  pattern  However,  significant  body  r e s u l t s were gm  may  and  not  in  time.  a  condition As  over  useful  the  data  discussed  contradictory.  weight, be  in  It  density  indicator  were earlier  in  this  that  for  tested,  body  appears range of  detected  density-induced  84  EXPERIMENT  3:  STRESS  RESPONSES  IN  SMOLTS  AND  PRE-SMOLTS  Introduction  This  experiment  responses density grams.  to  rearing  changes The  This  is  the  From  populations  of  which  last  the  few  most  February juvenile  process  of  have  authors  have  process  to  here  The at  two  (3b), The  hatchery  these  different  was  partial  Although  L i and  repetition  of  (1977)  on  and and  second  and  other  smoltification described  volume  and  stress  volume  effect  have  detected  Most  these  studies  such were  Refstie  responses  The  major  tank  growth  and  Wedemeyer  stress-related  authors  Aulstad  behavioral  period.  no  conditions.  undergo involves  These,  the  found  of  size  densities.  of  rearing dwelling  experiments  this  the  effects  Brockson other  of  compared  rates,  Discussion).  hatchery  during  the  process  13).  The  release.  stream  (1981),  (Table  constant  the  wild  This  practices.  and  in  30  conducted  before  appropriate  sensitivity  loading  trout,  period  the  sudden  averaged  were  rearing  Dickhoff  changes  (3a)  ( 3 c ) , examined and  rainbow  (General  a  of  and  weights  April,  and  responses  widely  third,  under  of  the  rearing  stress  first  densities  of  emphasized  examined  months  i n which  rate  morphological  Folmar  described these  flow  studies  smoltification.  (1976),  sections  Initial  s t e e l h e a d of  changes.  3  volume,  these  until  physiological,  (1981)  into  critical  biochemical, Hoar  tank  examined.  over  probably  process.  the  to  divided  density,  were  period  corresponded  was  not  second,  experiment. at  equal  response. on an  growth effect  conducted  (1975)  noted  85  Table 13. P h y s i o l o g i c a l changes a s s o c i a t e d smolt transformation i n salmonids (from 1980).  PHYSIOLOGICAL  -  -  L E V E L I N SMOLTS COMPARED WITH PARR  body s i l v e r i n g , f i n m a r g i n b l a c k e n i n g increases hypoosmotic regulatory c a p a b i l i t y increases s a l i n i t y tolerance and preference increases weight per u n i t length ( c o n d i t i o n f a c t o r ) . decreases growth r a t e increases body t o t a l l i p i d c o n t e n t decreases oxygen consumption increases ammonia p r o d u c t i o n increases l i v e r glycogen decreases blood glucose increases endocrine a c t i v i t y increases t h y r o i d (T4) interrenal p i t u i t a r y g r o w t h hormone g i l l m i c r o s o m e Na+ K+ - A T P a s e e n z y m e a c t i v i t y , increases a b i l i t y t o g r o w i n f u l l s t r e n g t h s e a w a t e r .. . i n c r e a s e s buoyancy increases migratory behavior increases  significant different rainbow  there  differences  tank  depths,  in  growth  but they  rates  in  d i d not detect  coho this  reared effect  at in  trout.  The  in  CHARACTERISTICS  with the parrWedemeyer e t a l .  will  null  hypotheses  of the experiments  are that  b e no d i f f e r e n c e s , a t t r i b u t a b l e t o t r e a t m e n t  effects,  any of t h e v a r i a b l e s  f o r each  measured.  86  Materials  These designed  experiments  s a  c o n t i n u a t i o n s of  permissible in  these  for  at  fish  densities  experiments  least were  densities In  two fed  during  the  first in  growth  stress  weight Tank 24  1/min.  per  times  the  low  density  rations  projected  ascertain water  supply  would  have  containing  fish)  to  fish,  experiment  the  experiment,  was  effects  was  350  to  of  flow the  of  summarized  used 10  °C  A l l  Rearing  flows  at  high  was on  density  growth  in  Table  as  in  at  400  and  levels.  more  1/min.  set  fish about  hatchery. had  a  While  an to  since,  to  due  experiments  more The 14,  The  important  small-scale  10  9.5°C  density  the  two  of  on fish  was  were  density  traditional i t  was  Initial  expected  used  the  study  varying densities  maximum  of  to  week.  density  the  rates  flow  Maximum  study.  temperature  Therefore,  a  9.5  this  examined.  and  other  at  final  widely  maximum  desirable, of  tanks  simple  commonly  half  received is  a  a  were  before. A l l fish  rearing 1,  and  gm/1.  were  The  flows.  set at  second the  of  1981,  experiments.  the  20-30  one-eighth  density  as  during  grams.  was  two  start  (3a), a  density  different  Photoperiod  the  presmolts  adjusted  February  in circular  effects  constraints,  50  first  were  experiment,  density  the  the  conditions allowed  final  intermediate  In  period  maximum  (50  13  to  This corresponded  3.8  this  full  30-32  were  These  tank.  prior  in  on  held  the  methods  calculated  weeks  which  averaged  volumes  were  were  this  conducted and  began  and  tanks,  each  design tanks  of 1-6.  10L:14D. study,  effects  of  (3b),  changes  in density  the were  second  major  examined. A l l  87  T a b l e 14. comprised study 3c. t a n k s were  Design of experiment 3. T a n k s 1-6 ( u p p e r table), s t u d y 3 a . T a n k s 13-16 ( u p p e r table), comprised T a n k s 7-12 ( l o w e r t a b l e ) c o m p r i s e d s t u d y 3 b . A l l h e l d a t 9.5 C. F l o w r a t e i n s t u d y 3b was 18 1 / m i n .  TANK NUMBER FISH  1 2 3 4 5 6 1 3 14 15 16  VOLUME litres  400 50 50 400 50 50 250 250 500 500  DENSITY — INITIAL — fish/1 gm/1  FLOW 1/min  350 350 350 350 350 350 250 250 500 500  24.0 24.0 10.0 24.0 24.0 10.0 12.5 12.5 25.0 25.0  FINAL  34.2 4.2 4.2 34.2 4.2 4.2 30.0 30.0 30.0 30.0  1.14 0.14 0.14 1.14 0.14 0.14 1 .0 1 .0 1 .0 1.0  PHOTOPERIOD lighl  gm/1 ' .h o u r s  62.7 7.8 7.8 62.7 7.8 7.8 55.0 55.0 55.0 55.0  10 10 10 10 10 10 14 14 14 14  FIRST —DENSITY-SECOND DENSITYTNK VOLUME I I N I T I A L F I N A L VOLUME I N I T I A L F I N A L AVE ' F I S H l i t r e s f/1 gm/1 gm/1 l i t r e s f/1 " - gm/1 7 8 9 10 1 1 12  300 300 300 300 300 300  tanks  500 500 500 500 250 250  contained  9.5°C. A g a i n , used. 1  0.6 0.6 0.6 0.6 1 .2 1 .2  throughout  were  summarized weights, (low  given  densities tanks,  500 500 250 250 500 500  fish,  and  replicated  the  midway reverse  would and h a l f  27 27 54 54 27 27  0.6 0.6 0.9 0.9 0.9 0.9  of 2 tanks  had t h e i r  through  the  treatment. Based  approach  66 gm/1  in  the  each,  o f 500  volumes  halved  and  two  experiment  projected  i n the high low  were  volume  study,  This  on  10 10 10 10 10 10  o f 18 1/min a t  at a constant  tanks  7-12.  that  33 33 66 66 33 33  received flows  held  Two  14, t a n k s  0.6 0.6 1 .2 1 .2 0.6 0.6  treatments  were  study.  doubled)  i n Table  volume)  27 27 27 27 54 54  two t a n k s  the  densities  others  300  three  As b e f o r e ,  (i.e.  18 18 18 18 36 36  PHOTO hrs light  density  i s  final density tanks.  88  Photoperiod In  the  different Both  was  tank  litres about are  55  others,  was  room.  experiment  was  important  3b  assumed  insufficient  fish.  This Since  were  tanks  date  fish 3/32  no  the  tanks  by  more  than  as  of  the  well  water  water  to from  frequently,  9.2°C. several and  and  frequency first  6/64th  used  well  8  inch  which,  experiment  unlike  a l l  the  in  the  not  14L:10D the  cycle.  results  of  Unfortunately, were  available  include  2-ocean  temperatures  temperature  food  the  the  directly,  the  were  was  adults  from  For  Tanks  analyses.  water  9.5  2.  in a l l tanks  a  to  achieve  250  effects.  0.3°C  Abernathy  pellets  on  necessary  in  from  more  before.  received  set  were  containing  of  study,  3-ocean  Well  received  monitored  of  i t was  experiment  of  factor  i n t e r p r e t a t i o n of  progeny  received  a  laboratory,  volume  infrequently.  quantity  determined  since  is considered  were  The  was  effect  tanks  This  here  To  design  of  investigated.  basis).  density  the  wet  Therefore,  some  fluctuated  of  of  effects  b a s i s ) , and  tanks  final  the  study.  measured  shortages  all  numbers  most  throughout  Photoperiod  gm/1  by  and  13-16.  in  a  the  were  inflow  fish  details  conducted  (on  differed  500  tanks  (3c),  stress  of  Expected  Pertinent 14,  and  densities  flows  had  study,  growth  gm/l/min  fish.  in Table  this  on  rates  250  study  for  a  litres  gm/1.  quarantine  small-scale  identical  (on  500  had  given  This  had  loading  containing  10L:14D.  volumes  loaded  similar  at  third  tanks  equally  set  days  Because  of  water  sources.  These  temperatures  rarely  source. of of  feeding the  crumbles.  because  decreased  of  were  experiment, After  their  this  different  89  shape,  were  Total 54,  61  and  larger. weights  were  collected  72.  a l l  tanks  specified  days.  following  days:  collected being  1,  8,  18,  days  61  32  and  and  and  experiment  3b  11,  No  since  was  18,  39,  48,  each  of  the  collected  on  the  on  were  72.  61  i t  1,  measured  data  32,  for Cortisol  days  were  Length-weight  between  sampled  handling  Not  on  measurements fish  were  desirable  stress.  In  densities  assess  Cortisol  concentrations  to  pre-density  32,  were  were  frequently  to  minimize  adjusted  on  day  48. To  experiments, 3b,  blood  effects from day  and  samples of  study  analysis. 47,  on  were  collected  Since  the and  samples  enabled  sampled  had  collected  on  day  54.  poor  not  growth  day  samples  data  47.  To  were  again  A l l tanks  were  on  47  of  full day  47  for  the study  assess  sampled  film  and  these  quality  73.  the  collected again  on  still  fish  stomach  stomach  for  should  proximate  in progress  before have  fullness.  reasons,  on  sampling. been  Fortunately,  content  logistic  74  both these  A l l  only  fish  samples  processed. were  recorded  T e c h n i c a l problems  data was  and  treatments.  For  observations and  were  starve  the  between  were  59,  to  in  i n s p e c t i o n of  52,  Water  food  stomachs.  days  experiments  appropriate  constant  Behavioral 45,  the  effect  small  a  on  d e n s i t y changes,  tanks  i t was  However,  31,  collected  adjustment  through  74. Samples  day  were  sudden 3b  obtain  mid-way  were  excluded  monitored  less  on  video  on  days  on  day  17  from  the  analysis.  frequently  resulted  in  17, in  these  90  experiments two  than  reasons.  suggested  First,  that  conservative. these  last  allowed.  results  t h e method  Secondly,  Consequently,  however,  from  oxygen  summarized  the  were  i n Table  the  This  were  only  70-80%  were  were  1 2 3 4 5 6 7 8  - 12:45 13:15 13:15 13:55 1 3:55 1 4:22 10:40 10:52  8.80 1 0.95 10.75 9.1 5 10.90 10.90 9.20 9.00  phase  periodically  as h i g h  1981);  however,  groups  of f i s h  were  Transport to  stress  regulate  1 1 1 1 1 1 1  a salt  not  fish  has been  salts  TANK  feeding  given  was  test  as  used  In  in  the  addition  At a l l  data  was  predictions  a t t h e end of  checked.  Oxygen  times,  f o r d a y 73 a r e  9 0 1 2 3 4 5 6  water  11:05 11:30 11:30 12:35 1 5:00 1 5:00 15:00  8.35 9.40 8.50 8.90 8.30 8.50 8.60  -  -  ended  on  to Vancouver  challenge at may  t o reduce  i n a hyperosmotic  the have  3.  OXYGEN mg/1  day  c o n t i n u e d a n d o n May  available  shown  f o r experiment  TIME hrs.  of the experiments  April  transporting  densities  15.  OXYGEN mg/1  water  experiments  actually  collected  satisfactory.  TIME hr s.  Salt  two  high density.treatments only.  TANK  growth  acceptable f o r  maximum  densities  T a b l e 15. Summary o f d i s s o l v e d o x y g e n d a t a Measurements a r e p r e s e n t e d f o r day 73.  The  was  first  of c a l c u l a t i n g  samples  levels  levels  of  t h e maximum  experiments  experiment  oxygen  i n the p r e v i o u s ones.  6  74  ( d a y 82)  test. hatchery  produced  the a b i l i t y  environment  (27  of  (Iwama  and  stress. smolts 1979).  91  Consequently, artificial  the  sea  or  a  To  a  and  minimize  levels,  model  system  i t was the  equipped  pers.  in  carbon  stress  salt  water  the  the  hatchery  minimum  system  Brett  required  to  were  and  The  use  using  Zala  (1975)  effects  of  been  Neither  were  static  bath.  stressful  approximated and  of and  considered. With  volume  a  have  reaching  dioxide production, were  should  bio-filters.  metabolites  rates  comm.).  pH,  to  water with  of  production  temperature, due  at  therefore necessary  presented  (Tautz,  salt  liklihood  ammonia  information  conducted  flow-through  closed  available,  was  water.  Ideally, used,  test  using  the  oxygen  fish the  this  size,  additional information  water  for  the  test  was  allowed  free  circulation  approx imated. A  vexar  water  mesh  within  compartments enabled  since  were to  separated be  catecholamine  release  shifts  in g i l l  (Eddy  1981).  Individual  wide  by  9.5°C,  and  to  temperature, chilled The brand.  a  constructed.  black  from  stress  rapid  cm  was  with  removed  Minimizing  27  that  compartments,  fish  neighbours.  h o l d i n g cage,  one  by  50  i t  from  heat-exchanging  cm  Adjacent sheets.  without  sampling  associated  compartments  prevent  section  during  p e r m e a b i l i t y and  across  polyethylene  with  stress  deep.  important can  Temperature  coil  was  was  "Forty  to  improvised  cause  performance  approximately  increasing  This  disturbing  was  osmoregulatory were  of  was  30  cm  set  at  ambient to  air  circulate  water. artificial The  salt  chemical  used  composition  Fathoms  i s provided  Marinemix"  i n Appendix  I.  A  92  hydrometer  (Fisher  to  salinities.  check  used  to  correct  anomaly. prior  The  to  Iwama  fed  for  challenge in  a  were  the  procedures  24  not  test  fish  and  from  introduction  was  As  to  near  treatment  24  hours  water  strong solution  caudal Plasma  peduncle was  tubes. were  Both  a  If  units,  were  they  salt  to  Fish  f o r 24  in  hours  after.  those  described  Fish  were  to  be  from  as  was  volume  used  individually  bath  used  (1977)  vigorously  A l l fish  possible,  and  placed of  a  one  not  in  the  weighed treatment  group.  the  with  test.  Twenty Time  of  model  were  443  used  variation  as  removed  bucket  from  containing  Before  dilution  syringes  with  or  cation-free  determined and  flame  the salt  sampling, of  the  the  plasma.  microcapillary heparin.  Samples  on  samples  diluted  measured  in  photometer.  an Zero  s t a n d a r d s . Samples  between  r e - r u n , and  were d i s c a r d e d .  were  iced.  levels  were  in a  prevent  either  treated  fish  anaesthetic. to  standard,  Inc.,  duplicate.  they  and  sodium  / l solutions  the  dried  been  lithium  Laboratories +  had  centrifuged  with  Na  was  collected  Plasma  water.  used  specific  (1977).  were  was  Chester  on  less  testing.  were  as  compartment,  a  °C,  recorded.  appropriate and  and  closely  a n a e s t h e t i z e d , but  introduced into  each  and  Blackburn  to  0.1  aerated vigorously  corresponded  prior  ±  effects  fish  p r e - t a r e d c o n t a i n e r of held  in Riley  was  C l a r k e and  hours  were  2.1  solution  (1979) and  accurate to  temperature  salt  test  Table  for  introducing  The by  Scientific),  duplicates  i f differences  was were  Instumental and  140  meq  assayed  in  greater than  10  were  still  large,  93  Results  Growth  Experiment In stress four  this  3a experiment,  r e s p o n s e were examined  of the f i r s t  growth  slope  Changes  i n adjusted  slope  data.  Bartlett's  eleven  test  (Table  showed  that  calculated.  LT-test  time  was  problems  the  deletion  5 and 6 f o r that  i n Figure  9.  calculated  f o r the  growth  analyse  effect  of  interval.  were n o t s i g n i f i c a n t .  comparisons  during  are given  variances  to  No s i g n i f i c a n t  1 4 ) .Feeder  tanks  over 16)  o f d e n s i t y a n d f l o w on  necessitated  effects  therefore necessary  Mann-Whitney  (Table  from  weights  Treatment  effects  days  information  A 2-way ANOVA  was  the  However,  were h e t e r o g e n e o u s ,  and i t  by  means.  non-parametric  (2-tailed, of either  5%  flow  level)  were  or density  was  detected. Over  the  Although  there  growth  at  range was  tested, a  reduced  d e n s i t y h a d no e f f e c t  non-significant flows,  the  trend  effect  on g r o w t h .  towards  was  not  reduced  considered  important. Referring Bartlett's time  test  without  significant previous pattern  back  to  the  indicated that heterogeneity  (df=6,39 p<.05).  experiments, (i.e. rise  growth  t o a peak  ANOVA  presented  growth  rates could  problems. In contrast slopes after  a  in  Table  be a n a l y z e d  The e f f e c t s  of time  to the results  d i dnot follow the low  initial  16,  of  by  were the  expected  period,  and  94  Figure  9. C h a n g e i n w e i g h t o v e r t i m e f o r e x p e r i m e n t s 3a, 3b, and 3c. A l l w e i g h t s h a v e b e e n a d j u s t e d t o a common i n i t i a l w e i g h t o f e i t h e r 30 o r 33 g r a m s (33 g r a m s i f f i r s t i n t e r v a l g r o w t h d a t a h a d t o be d e l e t e d ) . Changes o v e r t i m e were c a l c u l a t e d u s i n g g r o w t h slope informat i o n .  ^  60  t  400 fish - 24 1/min 50 fish - 24 1/min 50 fish - 10 1/min  50 +  40 +  30 60  TIME (DAYS)  T  constant density low to high density high to low density  50 +  S  40 +  30  -  0  60  10  20  30  40  50  60  70  TIME (DAYS)  T  high volume low volume  50 +  40 +  30  0  10  20  30  40  TIME (DAYS)  50  60  70  80  96  T a b l e 16. Analysis of variance of growth s l o p e experiment 3, part A ( s e e t a b l e 14, part A). considered significant i f p < 0.05. Data from i n t e r v a l s were a n a l y s e d .  SOURCE  Treatment Time Treatment*Time Residual Total  then  decline  erratic three  This  there  (Duncan's  increase  associated  time  plotted  in  During  first  the 6  tanks,  growth  slope  first  interval.  may  hyperactive,  and  As  of  numbers  corrected  within  Because  the  first  time  growth  Over  growth  three  tanks  showed  the  growth Growth  was  the  to  last  increase.  times  were  this  not  pattern.  acceleration slopes  the  tanks  the  time few  appeared  to used  was  feeder  jumped  a  interval  feeder  in u n r e l i a b l e data.  of  problems  fish  times,  experiment,  for a l l 6  at  and  for  last  of  this  recounts  experiment,  the  part  necessitated were  4  against  10a.  result  large  first  trend  a l l 6  resulted  a  the  smoltification.  days  information  0.09846 0.01284 0.36346  predictions).  a  be  in Figure  3b  of  was  with  Exper iment  4  model  test),  i f real,  process are  to  During  d i f f e r e n c e s between  significant  PROBABILITY  0.00000666 0.00000944 0.00000298 0.00000253  close  intervals, the  2 6 12 19 39  thereafter).  (although  Although  MEAN SQUARE  DF  data from Tests are a l l time  out  of  next  days  of  behave in  Consequently,  deleted  problems, of  the  problems  some  fish  A l l  start  "normally" analysis  the  became  tanks.  weighing. the  for  This feeder  of by  day  the 7.  extended  97  Figure  10. Growth s l o p e s a g a i n s t time (mid-point of sampling i n t e r v a l ) f o r e x p e r i m e n t s 3a, 3b, a n d 3 c . Growth s l o p e s w e r e c a l c u l a t e d a c c o r d i n g t o Iwama a d T a u t z (1981). V e r t i c a l bars are standard errors.  0.020 D_ O  I  400 fish 50 fish 50 fish  24 1/min 24 1/min 10 1/min  0.015  OO  § 0.010 CD  0.005 0.020 r  B LU D_ O  i  constant density low to high density high to low density  0.015 -  OO  rn 1— 0.010 to 1 1 • 0.005 •• CD 0.000 +• 0.020 T £  high volume low volume  0.015 +  o  oo  o oc  ^  CD  0.010 + 0.005 + 0.000 0  10  H  20  h-  30  40  50  MID-POINT OF TIME INTERVAL  60  70  99  from  day  affected  11  data  density  i t  analysed  treatments  were  the  same  (low  over  time  that  the feeder  groups.  Growth  (density  groups average  ANOVA  (Table  significant.  which  in  problems  were  mean  growth  are given  i n Figure  test in  significantly  not d i f f e r e n t . but  Both  treatment  was  The two  different  t o l o w ) , were  different  17).  Duncan's  the  doubled)  density,  to high, or high  significantly  patterns  2-way  were  reduced  i n the other  with  in a  effects  two h o m o g e n e o u s  than  i s unlikely  results.  time  volumes  groups  have  were  and  produced  lower  18,  subsequent  The  which  to  volume  not expected t o  slopes.  Growth  slope  10b.  T a b l e 17. Analysis of variance of growth s l o p e d a t a from e x p e r i m e n t 3, p a r t B ( s e e t a b l e 14, p a r t B ) . T e s t t e r m s are c o n s i d e r e d s i g n i f i c a n t i f p < 0.05. Due t o t e c h n i c a l diffic u l t i e s , d a t a from t h e f i r s t t i m e i n t e r v a l were d e l e t e d . The s i g n i f i c a n t i n t e r a c t i o n t e r m was t h e b a s i s f o r r e a n a l y s i s b y s e l e c t e d time intervals.  SOURCE  DF  Treatment Time Treatment*Time Residual Total  2 6 12 21 41  Duncan's  test  however,  none  processes  since  pattern The  observed  of  produced these  no  MEAN SQUARE  PROBABILITY  0.00002167 0.00001294 0.00000908 0.00000273  several groups  patterns  were  groups offered  term  was  on t h e b a s i s insight  detected.  i n t h e p r e v i o u s major  interaction  0.00270 0.00335 0.00773  The  experiments  significant,  of time,  into  growth  curvilinear was  a n d i t was  absent. therefore  100  decided  to  volumes  were  When density  reanalyze  the  data  the  first  effects  four  were  times  not  u n a f f e c t e d over  first  47  days  the  of  high  conventional  the  densities (df=3,23  time  the  significantly  a  analyzed  2-fold  tanks at  before  On  and  a  after  in a l l groups.  more Time  third  ANOVA  Therefore  during  weight/volume  s l o p e s were  The  2-way  in density  hatchery.  the  a  p=.42).  slightly  Growth  of  in  (df=2,23  range  were  the  p<.005).  exception  lower  were  experiment.  density  significant with  groupings  significant  was  47,  time  adjusted.  growth  day  by  the  basis,  than  by  twice  effects  were  constant  over  interval  interaction  which  term  was  was  not  signi f icant. The  results  of  a  2-way ANOVA  f o r the  last  treatment-related  differences.  Density  effects  (df=2,17  Those  at  density  about  p<.00l).  60%  slower  treatments the  fact  the  tanks  period  had that had  they been  considerably  (0.0125  low  had  high  density  were (low  groups.  e q u i v a l e n t growth  different  reared at  the  following  density high  Both  sgnificant  low  slopes,  grew  density despite  ( i . e . two  until  changes  produced  volume)  histories  density  density  times  day  47).  elicited  of The the  response.  Interestingly, were  the  statistically  immediately  greatest  than  groups  3  versus  compared.  This  mean  growth  higher  0.0097) supports  than  when the  slopes for  tanks  over  the  the 7,  trend observed  9,  last  3  intervals  first  four  intervals  10,  and  i n experiment  12 3a.  were  -  101  Experiment  3c  Technical  difficulties  experiment,  interval.  were  analysed.  effects  data were  were  i n a 2-way ANOVA  analyzed  not s i g n i f i c a n t .  predictions  (0.0091), above  towards than  with  (Figure  approximated  10c)  the  last  the  pattern  was  conducted. Since  was  time  important three  that  were  the  different  two  similar stock  stocks effect  associated faster  on have  with  growth  parents.  been  data  and t h e most stocks pooled  volume in  fish  model  which  grew  and the o v e r a l l  pattern  3a  increased  and  3b.  growth  over  the p o s s i b i l i t y  that  which  the  by a l m o s t  obtained.  source  in a  research  15%,  Obviously  of v a r i a t i o n this  i t  was  possibility,  1-way  ANOVA.  The  p o s s i b l y due t o t h e v a r i a n c e  However which  volume  To examine  there  t h e were  some o f t h e v a r i a n c e  may  present  the  volume  varied  not  and analysed  effects.  low  slopes  in  likely  used.  the  different  was  intervals  s l i g h t l y below  i t reduced  were  first  1 8 ) . Volume  experiments  o f t h e room  means  in  of the  the  6 time  Growth  towards  was n o t s i g n i f i c a n t ,  Therefore  volume  since  significance  large  were  in  was t h e t r e n d  the treatment  variances  p<.05),  from  (Table  at high  (0.0109).  those  intervals,  fish  growth,  fish  (df=5,23  was a n a r t i f a c t  surprising  lower  predictions  significantly  the remaining  However,  those  few d a y s  data  only  tended  Especially  first  Consequently,  treatments  slightly  the  n e c e s s i t a t e d d e l e t i o n of growth  time  The  during  was  progeny  i n the  be d u e t o s t o c k  effects.  b u t , i f s o , i t was  small.  a  ANOVA  A volume  trend  for  o f 3-ocean conducted effect  may  1 02  T a b l e 18. A n a l y s i s of variance of growth s l o p e data from experiment 3, p a r t C ( s e e t a b l e 14, p a r t C K Tests a r e cons i d e r e d s i g n i f i c a n t i f p < 0.05. Due t o t e c h n i c a l difficult i e s , d a t a f r o m t h e f i r s t t i m e i n t e r v a l were d e l e t e d .  SOURCE  DF  MEAN SQUARE  Volume Time Volume*Time Residual Total  1 5 5 12 23  0.00001175 0.00001449 0.00000311 0.00000291 -  Proximate  Results  parametric  3a  of these  Moisture:  comparisons  replicates  had  significantly  with  calculated  necessary.  different.  replicates higher  pooled. moisture  treatments  were  Treatments covariate  Parametric  entered had  no  in a  in a  With  with  on  The h i g h  than  agreed  with  protein test  pooled,  The e f f e c t ,  only  comparisons  tests were were  treatment  t h e low d e n s i t y that  were  found  observed between  flows.  adequate with  that non-  density  levels  were  of slope  replicates  1-way ANOVA.  Subsequent  11.  U-test  In one c a s e  different  1-way ANOVA  effect  demonstrated  No d i f f e r e n c e s  tests  nor the e q u a l i t y  Lipid: examined  two e x p e r i m e n t s .  c o n t a i n i n g 50 f i s h  Protein:  trend  i n Figure  Mann-Whitney  replicates.  ( U s = 5 7 , Uc = 4 9 ) . T h i s  the f i r s t  which  were  statistically  on d a t a  a r e summarized  ANOVA  f o r treatment  done  in  analyses  The f i r s t  calculated  tanks  0.06749 0.01063 0.42484  Analysis  Exper iment  were  PROBABILITY  for  weight  Neither  the  significant.  density  although  data  as a c o v a r i a t e .  content. were  these  effects  were  not s i g n i f i c a n t ,  1 03  Figure  11. Histogram of proximate composition data f o r experiment 3a. A-moisture, B-protein, C-lipid, D-ash. Means a r e g i v e n w i t h s t a n d a r d e r r o r s . Bars bearing common s m a l l - c a s e l e t t e r s a r e n o t s t a t i s t i c a l l y different (Duncan's o r S c h e f f e ' s m u l t i p l e range t e s t 5% l e v e l ) . S t a t i s t i c a l c o m p a r i s o n s w e r e made b e t w e e n the f i r s t 2 columns ( d i f f e r e n t density, equal flows), and t h e l a s t 2 columns ( e q u a l d e n s i t y , d i f f e r e n t flows).  o  ASH (% DRY WEIGHT) CO  CD  LIPID (% DRY WEIGHT) O  H  ro  ro -Cr  PROTEIN (% DRY WEIGHT) ro  cn  CD -Cr  cn cn  cn oo  MOISTURE CD  ro  Jr  m i i 1  CO  »  «  -<  J=CD  -n t—•  ro  —1  CD \  CO X  -1  >  z  v—*  o ro -n _t i— o  H  ^  —i  vn CD  CO  1—  m  \  1  O  z  (7  105  was  close  (df=1,15  p=.12),  direction,  i . e .decreased  Furthermore  there  or  were  the interaction.  examined  in  tanks  decreased  flow,  and the t r e n d lipid  followed  content  no s i g n i f i c a n t  the  expected  at the higher  density.  effects  of  the  The e f f e c t s  of varying  flow  containing  identical  densities.  lipid  levels  were  significantly  covariate  r a t e s were  then  At  reduced  the  (df=1,15  p<.005). Ash: in  a  With  1-way  (df=1,15  replicates ANOVA.  p<.05),  pooled,  There  was a s i g n i f i c a n t  ash content  Flow  effects  were  ash  content  was  also  the density data  decreasing  significant  higher.  effect  of  analyzed  of density  a s d e n s i t y was  (df=1,15  Effects  were  reduced.  p<.05). A t low  the  flows  c o v a r i a t e were n o t  signi f icant.  Experiment  3b  As m e n t i o n e d were there  collected were  four  i n t h e methods,  just  prior  tanks  There  analyses  a r e summarized  calculated.  covariate  Using  were term  adjustment.  Until  two  t h e r e f o r e , two t r e a t m e n t s .  The e f f e c t  replicates  t o volume  f o r proximate  a t t h e low d e n s i t y a n d  density.  Moisture:  were,  samples  i n Table weight  nor  that  at  Results  a  the  high  of  these  1-way ANOVA  o f d e n s i t y was n o t s i g n i f i c a n t ,  the  time,  19.  as a c o v a r i a t e ,  different  analysis  (df=4,23  equality  of  p<.00l). slope  test  was  although  Neither  the  term  were  these  data  significant. Protein: indicated  that  A  similar  replicates  analysis could  be  performed pooled.  on When  pooled  the  106  Table 19. Whole body proximate composition of juvenile s t e e l h e a d t r o u t from samples collected f r o m e x p e r i m e n t s 3b and 3 c a f t e r 47 d a y s of rearing. F i v e f i s h were collected from each tank, and d i v i d e d i n t o two s i z e g r o u p s . Fish from e a c h g r o u p were h o m o g e n i z e d and analysed i n d u p l i c a t e . The two s t u d i e s w e r e a n a l y s e d separately with a n a l y s i s of c o v a r i a n c e a n d D u n c a n ' s t e s t . Common l e t t e r s r e p r e s e n t n o s i g nificant differences. DENSITY 0.6 1 .2 fish/1 fish/1  VOLUME 250 500 litres litres  MOISTURE  n mean S.E.  16 72.81a 0.058  8 72.71a 0.082  8 73.78a 0. 1 02  8 73.61a 0. 102  PROTEIN  n mean S.E.  16 66.11a 0.313  8 66.53a 0.446  8 67.96a 0.549  8 68.26a 0.549  LIPID  n mean S.E.  16 25.16a 0.284  8 25.31a 0.404  8 22.40a 0.219  8 23.48a 0.219  ASH  n mean S.E.  1 6 8.74a 0.270  8 9.64a 0.562  8 8.27a 0.562  ef f e c t s  of  covariate p<.001), levels  density term  decreased.  was  Ash:  With  ash  content  signi f icant.  significant  significantly that  as  term  replicates  pooled,  detected.  than  p=.45)  zero  (df=1,23  increased,  protein  was n o t s i g n i f i c a n t .  analysis,  terms  (df=1,23  weight  (df=4,23 p<.05).  of the other  was  less  fish  the protein  significant None  not  The i n t e r a c t i o n  As w i t h  detectable.  on  was  indicating  Lipid: term  were  8 8. 1 6a 0.384  were  only  the  No e f f e c t  replicates  of density  was  sigificant.  no d e n s i t y A l l other  effects terms  of were  density non-  107  Experiment  As  with  replicates were  3c  the growth  probably  analyzed  for  results  of the analyses  (Table  19);  effects  existed.  however,  A  indicated  other  were  replicates  term  Protein: As  with  p=.051)  protein  Replicates Ash:  no  p=.15) t o w a r d s  stock  effects  using  effects with,  the  Only  the  presented that  weight  (df=1,15  analyses  were  stock  as  a  p=.92).A l l  exception  treatments  between  performed  had  no  replicates  of  significant.  There  a t t h e lower  different  (df=1,15  the  effect  was  on  large a  data.  protein (df=1,15  trend  towards  lipid  content.  volume. affect  p<.00l).  not s i g n i f i c a n t , ash content  on p r o t e i n  were  did' not s i g n i f i c a n t l y  lower  be  d i d suggest  ANOVA,  volume  a l l data  effects. will  between  p<.00l).  levels  Although,  differences  Accordingly  analyses  nested  volume  Volume were  volume  the stock  Similar  but not q u i t e  Lipid:  on  (df=1,15  Variations  increased  stock  and  non-significant  moisture,  content.  volume  1-way  covariate, terms  analysis,  increased variances.  both  Moisture:  data  there  at high  was  a trend  (df=1,15  volumes.  Cortisol  As and  those  analyses were  described from  experimient  variances  tried  earlier,  were  b u t none  a l l tanks 3b w e r e  were  sampled  heterogeneous.  were  sampled  sufficient  three  Several to correct  at least times.  twice  I n some  transformations the problem.  In  108  these  cases  non-parametric  Experiment  Cortisol were need  (Figure  analyzed  replicates  effects  of those of  Comparisons fish),  not  density  were  present. Data  nested  treatment  When  I t appeared  (df=2,9l  unlikely  replicates  for  each  Cortisol  levels  were  significantly  = the  3.064;  50 f i s h  second  between  treatment  24 1 / m i n - c a l c  date,  replicates. pooling,  that  indicated  detected  at the high  a  versus  analysed  in a  decline  density.  comparisons  by  there  In  the  due t o  time  tests  were  were  made  a l l cases  second  date  24 1 / m i n - c a l c  were  variance, with  1-way  replicates.  50 f i s h ,  that  50  effects  differences  t=4.405)(critical  Due t o t h e h i g h  without  were  reduced  the  detected.  density  separately.  t=2.8685;  10 1 / m i n - c a l c tests  were  (400  that  pooled,  times  fish,  When  compared, non-parametric  With  with the  v a r i a n c e between t h e  significant  between  (400  treatments  date  comparisons  pooled  no d i f f e r e n c e s  date  indicated the  treatment.  p=.93) o r w i t h i n  were  test  be  due t o h i g h  no  sampling  U-test  could  density  sampling  were  t h e two t i m e s  required.  they  examined  significant  There  first  Mann-Whitney  the high  the second  ANOVA.  either  tests.  the  Bartlett's  t h e two d e n s i t y  tanks.  from  b y ANOVA.  were  between  were  required.  12a) f r o m  indicated from  flow  high  again  data  f o r non-parametric  exception  were  3a  initially  between  tests  t=1.96). no  i t  t On  differences  i s  unlikely,  would have  been  109  Figure  12. Histogram of plasma C o r t i s o l c o n c e n t r a t i o n s f o r e a c h o f e x p e r i m e n t s 3a, 3b, a n d 3 c , f r o m samples c o l l e c t e d on d a y s 4 7 , 54, a n d 7 4 . Mean v a l u e s a r e given with standard errors. E x p e r i m e n t s 3a a n d 3c w e r e s a m p l e d o n l y o n d a y s 47 a n d 7 4 . These data demonstrate the r e d u c t i o n i n plasma C o r t i s o l c o n c e n t r a t i o n w i t h time. D a t a f r o m p a r t B, e x p e r i m e n t 3b, c o l l e c t e d on d a y s 47 a n d 54 d e m o n s t r a t e t h e C o r t i s o l r e s p o n s e t o changing d e n s i t i e s . B a r s b e a r i n g common l e t t e r s are not s t a t i s t i c a l l y d i f f e r e n t (Duncan's or S c h e f f e ' s m u l t i p l e r a n g e t e s t s - 5% level).  03  o  CD  oo  — t -  CORTISOL  CORTISOL  CORTISOL  (NG/ML)  (NG/ML)  (NG/ML)  ISJ  -f-  -Cr  cn  H  oo  o  oo  1  —f-  hO  —I  -Er  cn oo  1  1  CD  hO  H  -Cr CD -Cr CD  O CD VAI  CD  o o  oo  1  CD CD  x <  CD CD  -Cr CD  X  01  o  CD I CD  t=3  CD CD  o o  CO  m  -Cr  I  o  VAl CD CD  hH "  CD Ul CD CD  x <  to  -Cr CD -Cr CD  CD CD ONI  CD CD  CD CD  X  hH °"  ro KJI  o  I-H o  -Cr CD  I— u n CD CD 1  hH °-  -Cr  1  cn  1  oo  1  111  Exper iment  Plasma  3b  samples  were  collected  last  were  t h e same a s i n t h e o t h e r  was  one  day  second  date  responses  was o n e week l a t e r  a n d was  intended  to detect  from  with  the changes time  were  pooled),  the  effects  not s i g n i f i c a n t  Data  from  the second  ANOVA  (replicates  were  not  i n the data  to  To  data  between  similar  test  from  density  analysed  density  a  1-way rearing  in a  treatment  there  sampling  treatments  mean p l a s m a those  changes  of  effects  were  period  on p o o l e d  Cortisol the  levels  last  were  (df=5,170  of time  were  the interaction that  time,  1-way  effects  interesting  showed data  no  (df=2,87  had decreased  sampling  date  in  correctly,  significant  two t i m e s .  so may  When  were n o t  pooled.  When  the effects  (df=1,l70  significant  of 'time'  analysed i n  replicates  p=.17) a n d were  was n e a r l y  the effect  were  included  compared,  ( o r more  not  term  the data  analysis  i n d e n s i t y ) were  effects  suggests  with  two t i m e s  different  changes  however,  of d i f f e r e n t  were  p=.13),  last  ANOVAs. E a c h  the f i r s t  the  Treatment  This  the  to  for  significantly pooled  in  3a.  2-way, n e s t e d  sudden  of  Interestingly,  experiment  analysed  (see below).  results  levels  two  (df=2,95  stress  p=.36).  date  pooled). Although  significant  differences  (df=2,79  sampling  The  in density.  the f i r s t  were  P=.19).  date  adjustments.  densities  The  first  The  (volume)  (replicates  trends  and  density  data  to  two s t u d i e s .  the f i r s t  the  associated  When ANOVA  prior  on t h r e e d a t e s ,  of  p<.005).  (df=2,170  p=.95),  (df=2,170  p=.08).  not have  been t h e  1 12  same  i n each  underwent revealed  different  were  volumes  increased  T h i s was e x p e c t e d  density  Cortisol  that  densities which  treatment.  were  halved  halved),  was a s l i g h t ,  In dates  the  2-way  replicates  Although  decrease are  with  time  interpretation  For  much  the of  of  differences  In tanks i n  Cortisol  doubled)  stress  levels  response.  were  doubled  not  significant  t h e second  The e f f e c t  tested,  significant  ( i . e . density (df=1,61  and l a s t  of time  was  i t  i s  sampling  significant  in  experiment  likely  that  the  i n a l l treatments.  These  data  12b.  growth  This  and  data  Non-parametric  the  which  levels.  comparing  these  simplicity,  comparisons.  in  time.  confirming the pattern observed  was  of the data  tanks  with  a  treatment  3c  with  differences.  Cortisol  pooled.  i n Figure  Experiment  volumes although  not s p e c i f i c a l l y  presented  As  ANOVA  were  ( d f =1,178 p < . 0 0 l ) , 3a.  where  i n c r e a s e i n plasma  those  indicating  i n tanks  P=.19)  from  ( i . e . density  Surprisingly,  each  Inspection  d i d not change  significantly,  there  changes.  levels  unchanged  since  was  testing  replicates i s not  variance  was  be o f s i m i l a r  were  pooled  strictly  likely  analysis  confounded  procedures were  procedure  and so s h o u l d  proximate  data,  by  stock  required.  f o r the pairwise  correct;  attributable magnitude  however, to  between  stock volume  treatments. When sampling  the effects dates  of d i f f e r e n t  (Figure  12c),  volumes  fish  were  reared  compared in  low  at  both  volume  11 3  containers t=3.417  had  p<.00l;  differences Cortisol since  To  sampling fact  were  therefore  found  between result  was  surprisingly, result  unaffected when  unexpected  a  were  an  visited  i t was  near  was  a walkway,  i n the levels  were  were  compared.  Cortisol trends. Fish the  for this  most  i n one other,  anomalous  susceptible  and near  other  to  frequently  tanks.  Length  Experiment  The  GM  produced  Relations  3a  functional the  regression  following  of  equation  l n length ( r  pairs): ln  the  p<.01) a n d  differences  while  reason  were  by  Cortisol  separately.  reduction  tank  tanks,  obtained  tanks  analysed  this  that  (t=2.59l  of a l lother  The  surprising volume  levels  volume  increase.  the  reduced  experiments.  i n view  of  comparisons  p h o t o p e r i o d . No  significant  showed  as  two  by  tanks  to those  the high  i s u n c l e a r . However,  disturbance,  Weight  the other  1,  faster.  significantly  identical  replicates  show  were  I t was  further  i n t h e low volume  with  times  Consequently did  date  somewhat  (time  magnitude  i n the high  effects,  levels  almost  room  growing  levels  The  cases.  for fish  time  plasma  p<.00l).  i n both  higher  t o be  Cortisol  in  tank  were  lower  t=4.231  similar  tended  quarantine  This  2,  investigate  computed.  were  time  was  levels  they  second  significantly  Wt.  =  (-4.438) +  2.993  *  l n L.  2  =  against  .9731  n =  ln 1383  weight data  11 4  T a b l e 20. C o n d i t i o n f a c t o r d a t a summary. V a l u e s were c a l c u l a t e d f r o m a GM f u n t i o n a l r e g r e s s i o n of n a t u r a l l o g l e n g t h against natural l o g weight. D e t a i l s of the design are i n T a b l e 14. I n p a r t 2, d e n s i t i e s w e r e c h a n g e d o n d a y 4 8 . The 8 in brackets r e f e r s o n l y t o p a r t 2. In both o t h e r groups t h e f i r s t s a m p l i n g d a t e was o n d a y 1. D  1 (8)*  TANKS  part  *  part  part  When  18  AY 32  72  61  n  S.E.  1 4  0 .998 1 .001  1 .011 1 .026  0 .998 1 .019  0 .962 0 .988  0.991 1 .035  50 50  0.00645 0.00645  2 5  0 .984 0 .995  1 .016 1 .024  1 .017 1 .032  0 .942 1 .008  1 .001 1 .020  50 50  0.00645 0.00645  3. 6  0 .993 1 .000  0 .999 1 .010  1 .010 1 .018  0 .942 0 .991  0.984 0.992  50 50  0.00645 0.00645  7 10  1 .005 1 .003  1 .002 1 .006  1 .014 0 .990  0 .976 0 .986  1 .001 1.014  50 50  0.00647 0.00647  8 1 1  0 .996 1 .004  1 .023 1 .014  1 .014 1 .003  0 .975 0 .968  1.012 1 .019  50 50  0.00647 0.00647  9 1 2  0 .996 0 .993  1 .007 1 .010  0 .976 0 .997  0 .994 0 .992  1.017 1 .024  50 50  0.00647 0.00647  1 3 14  0 .997 0 .968  1 .004 1 .002  1 .015 1 .000  0 .968 0 .975  0.995 0.997  50 50  0.00702 0.00702  1 5 16  0 .988 0 .997  1 .015 1 .002  1 .016 1 .026  1 .008 1 .002  1 .043 1 .033  50 50  0.00702 0.00702  1  2  3  reorganized  and a n t i l o g g e d ,  the working  condition  equation  was: condition  factor  A  nested  2-way  effects  (df=2,1382  different over to  time that  tanks.  = weight/(0.01181955 ANOVA p=.47).  (df=15,1382 (df=4,l382 for  These  growth  data  produced  no  2  Condition  p<.01). The p a t t e r n with  are presented  time  9  ). treatment  significantly  varied  significantly  with  20.  3  were  a n d was  i n Table  9  significant  Replicates  p<.00l).  slope  * length '  time  was  consistent  similar ina l l  1 15  Experiment  The  GM  produced  functional  Wt.  when  =  The  equation  (-4.549) + 3.035  converted  condition  ANOVA  r e g r e s s i o n of l n length against  the- f o l l o w i n g  ln which  3b  were  pooled,  df=l5,1499  (df=2,1499  time  were  p<.00l).  of  growth  P<.001).  3a. The  was  between  not r e a d i l y  relation factor  between  response.  The 2  =  Wt.  and  3  analysed  same  3  effects  followed  in  (df=8,1499  minor  of the  pattern  interaction  of  i n Table  of that  occurred  a  d e n s i t y and  are presented  2-way  the effects  evidence  of changing  ). a  significant  no  5  Treatment  revealed only  was  0  in  trend  and the source  r e g r e s s i o n of  1000) i s p r e s e n t e d  clear  condition  20.  ln  weight  on  ln  length  below:  * l n L.,  becomes:  factor  i s the working When  length '  however,  was  data  ( - 4 . 8 4 9 ) + 3.138  rearranged condition  The  term  There  values  *  3c  n = =  the  the e f f e c t s Mean  1 500):  was:  p=.14).  p=.55),  time.  treatments  functional  .9707, ln  which  GM  of  n=  The p a t t e r n o b s e r v e d  interaction  apparent.  Exper iment  (r  over  Inspection  differences  formula  subsequently  not s i g n i f i c a n t  slopes  .9779,  weight  * l n L.,  were  (df=4,1499  =  = weight/(0.01057778  data  (replicates  experiment  2  to the working  factor  condition  ( r  ln  = weight/(0.00783621  *  length ' 3  1  3  8  ),  formula.  condition  data  were  analysed  in  a  2-way  ANOVA  11 6  (replicates effects  pooled  were  -  significant  respectively).  Fish  condition  factors  in  agreement  general  higher  volumes.  experiments pattern.  df=l0,999  the  than  those  The  3a  and  These  data  (df=1,999  from  with  low  the  pattern 3b,  are  p=.55),  volume  p<.00l;  volume  treatments volume  trend  for  increased  closely  mirrored  summarized  its  in Table  tanks.  lower This  growth  followed  own  time  p<.001,  had  high  time  and  df=4,999  i n the  with  and  both  at  that  growth  is  in  slope  20.  Behavior  Behavioral experiments times  and  3a  were  visible  on  In tank  and  then  1/min)  deleted  the  (300  obscured  data fish,  Data  were  over  the  low  to  the  presented  first  time.  affected from  be  Data  analysed  by  from  5  analysis.  activity last  high  separately  tank A  and  three  fish  dates  volume),  individual (50  faint  fish,  shadow,  24  only  distribution.  were  since  for  deleted  surface  for  glare  activity.  Net  nested  will  from  tapes,  Experiment  during  3b.  analysed  addition, 12  analyses  3a  Activity:  the  first  ANOVAs.  treatment  was  No  three On  greater  differences dates  the than  when  last in  between data  day the  treatments  were  analysed  activity other  i n the  were in  high  treatments  found 1-way  density  (df=2,209  p<.05). To  identify  patterns  with  time,  the  data  were  reanalysed  in  11 7  a  2-way  found.  nested  There  densities.  ANOVA.  was  a  Net  (df=3,8l9  p=.07),  tank,  f o r an  periods,  As trends  ANOVAs,  vary  was  net a c t i v i t y ,  with  time.  in  the  high  data,  there  density  p<.001).  Time  with  over  the  day  time  i n each first  3  (Figure 13a).  s e p a r a t e l y i n 1-  date  (day  activity  31)  were  i n t h e low  flow  p<.00l). data  were  effects was  a  were  trend  was  to  detect  not s i g n i f i c a n t . towards  were  p a t t e r n matched term  analysed  Replicates  effects  interaction  (df=8,8l9  repeated  analysed  first  treatment.  p<.05) a n d t h e o b s e r v e d 13b). The  were  day, t o t a l  the  Treatment  time  were  in higher  significantly  on t h e l a s t  the  (df=2,230  with  net a c t i v i t y  times  this  effects  different  a pattern,  with  decline  during  On  reduced  the  (Figure  not  there  When  only  found.  was  (df=8,980  significantly  did  a marked  treatment  for increased activity  increase in activity  differences treatment  trend  however,  Activity:  nested  significant  were  activity  and then  Total way  slight  Replicates  p<.005).  No  higher  that  activity  were  significant for  different (df=3,980  net  not s i g n i f i c a n t  As i n  activity (df=6,980  p=.84).  Experiment  Net  Activity:  treatments  was  sampling, the  space  Significant  differences  i n a l l b u t one s a m p l i n g  differences fish  3b  not  large  significant. (high  exhibited per  fish  volume,  date.  Treatments low  greater a c t i v i t y was  low.  These  Only  were on  i n which  density)  at  found day  between 59  the space the  time  levels  than  those  data  are  summarized  were per of  i n which in  1 18  Figure  13. A c t i v i t y a g a i n s t t i m e f o r e x p e r i m e n t 3a. Part A- n e t a c t i v i t y , p a r t B - t o t a l a c t i v i t y . Mean v a l u e s a r e i n d i c a t e d by h e a v y s o l i d l i n e s w i t h 95% C L . Lines a r e o f f s e t by one day e i t h e r s i d e o f t h e t r u e s a m p l i n g day f o r c l a r i t y .  DAY NUMBER  24 T  -|  20  1  30  i  40  — I  50  DAY NUMBER  1  60  1  70  \  80  121  Table  21 .  Table 21. Summary of net a c t i v i t y data by time and t r e a t m e n t f o r t h e s e c o n d s t u d y , 3b, ( s u d d e n d e n s i t y c h a n g e s ) of the t h i r d experiment. V a l u e s presented are transformed ( n a t u r a l l o g + 1.1), and are expressed in arbitrary units p e r 15 s e c o n d s . To determine t h e e f f e c t o f sudden changes in density, follow treatments a c r o s s time i n t e r v a l s . The mean v a l u e s o v e r a l l t i m e s ( l a s t column) shows t h e e f f e c t most c l e a r l y . As m e n t i o n e d i n the text, the observed effects may b e d u e t o v o l u m e d i f f e r e n c e s . FIRST --DENSITY-31 45  DAY  SECOND DENSITY 59  52  ALL  73  L--L  n mean S.E.  32 38 54 78 49 1 .819 1 .736 1 .877 1 .656 1 .742 0 . 1 174 0 . 1 003 0 . 1 2.03 0 .081 7 0 .0974  267 1.731 0.0441  L--H  n mean S.E.  70 1 .765 0 .0865  83 1 .410 0 .0809  90 73 83 1 .262 1 .480 1 .279 0 .071 7 0 . 0 8 4 4 0 .0748  412 1 .364 0.0354  H-- L  n mean S.E.  86 1 .246 0 .0781  56 1 .347 0 .0985  29 30 1 .708 1 .659 0 . 1 264 0 .1310  210 1 .461 0.0496  L-L L-H H-L  - c o n s t a n t low d e n s i t y ( h i g h volume) - low d e n s i t y t o h i g h ( h i g h volume t o low) - h i g h d e n s i t y t o low (low volume t o h i g h )  When were in  than  analysed  consistent  which  volumes  in  i n a 2-way  fish  volumes.  As  significance  over  a l l 5 times  t h e above  analyses. Activity  were  unchanged  was  in  i t was  spent  less  expected, (df=8,888  influenced  ANOVA  with  treatments  densities)  had  39 1 .449 0 . 1 092  which time the  p=.06)  activity.  greater  i n treatments  (df=2,888  not. At high  holding positions interaction  suggesting  the results  term  that  .p<.00l)  volumes (low than  was  changing  at close  low to  volumes  1 22  T a b l e 22. Summary o f t o t a l a c t i v i t y d a t a b y t i m e a n d t r e a t ment f o r s t u d y 2 ( s u d d e n d e n s i t y c h a n g e s ) of experiment 3. Values presented are transformed variables (natural log + 1.1), a n d a r e g i v e n i n a r b i t r a r y u n i t s p e r 15 s e c o n d s . T o determine the e f f e c t s of changes in density, f o l l o w mean v a l u e s a c r o s s time i n t e r v a l s . T h e mean v a l u e s o v e r a l l t i m e i n t e r v a l s ( l a s t column) d e p i c t s t h e e f f e c t most c l e a r l y . As mentioned i n the text, t h e o b s e r v e d e f f e c t s may be d u e t o volume. FIRST DENSITY 31 45  DAY  SECOND DENSITY 59  52  ALL  73  L--L  n mean S.E.  100 3 .861 0 .1041  100 100 3.688 3 .450 0 . 1 041 0. 1041  99 100 2 .788 3.651 0 . 1 041 0 . 1 0 4 6  499 3.487 0.0467  L--H  n mean S.E.  100 3 .079 0 .1041  100 1 00 2 .543 2.470 0 . 1 041 0.1041  1 00 100 2 .818 2.630 0 . 1 041 0.1041  500 2.708 0.0466  H'-L  n mean S.E.  1 00 2 .376 0 .1041  100 60 3 .018 3. 104 0 . 1 041 0 . 1 3 4 4  50 50 3 .428 2.611 0 . 1 472 0 . 1 4 7 2  360 2.859 0.0553  L-L L-H H-L  - c o n s t a n t low d e n s i t y ( h i g h v o l u m e ) - low d e n s i t y t o h i g h ( h i g h volume t o low) - h i g h d e n s i t y t o low (low volume t o h i g h )  Total  Activity:  significant  differences  differences suggests volume) (Table  were  that than  When  total  less  analysed  were  found  a t most  consistent  activity  net a c t i v i t y .  than  i s less  The  in  1-way times.  with  affected  general  nested  ANOVAs,  However,  the  net a c t i v i t y .  This  by  density  pattern  was  (and/or  the  same  20).  When pattern  analyzed was  significant different  in a  identical (df=2,1358  (df=13,1358  2-way to  nested that  p<.00l) p<.00l).  and  ANOVA  over  a l l 5 times,  above. Treatment replicates  In a d d i t i o n  the  were  effects  the were  significantly  interaction  term  1 23  was of  significant  ( d f = 8 , 1 3 5 8 p<.005)  volume and/or  Salt  Water  Challenge  Technical fish of  from the  first  pooled.  with fish from  each  replicate  were  were The  Evidently  large,  Because photoperiod  were  sample  since  parametric  (Figure  treatments (50-60  treatments  was  successful. For  of  each  The t r e a t m e n t  not tested.  randomly  A  analyzed  were  of  i n Table  parametrically, necessitated  large  enough  are presented  those  study  from  Scheffe's  containing high  test  data  treatments was  sodium  c o n t a i n i n g low d e n s i t i e s ,  identical.  two  a  different  were  initially  from  apparent  produced  densities,  r e g u l a t e d plasma  F-values  differences  were  r e a r e d under  3a a n d 3 b , t h e s e  density effect  however,  here.  3c w e r e  the four  from  23.  that  methods  of both  fish  non-parametric  the results  from  20  ( e q u a l numbers  are presented  fish  c o n t a i n i n g 300  total  selected  treatment  c o n t a i n i n g 50  variances, or  a clear  gm/1),  tanks  of  termination  by t h e h e t e r o g e n e o u s  fish  14)*  pooled.  details  s e p a r a t e l y . When  tested  replicate  sizes  analyses  than  attempt  v a r i a n c e problems  unaffected  analysed  was  first  of  effect  mixing  an e a r l y  t h e two t r e a t m e n t s  were  tanks). Design  heterogeneity  were  from  inadvertent  necessitated  second  v o l u m e ) was  treatment  Data  tests.  The  fish  flows  (low t o h i g h  including  treatments  Additionally,  different  ah  Test  test.  reasons  indicates  changes.  difficulties,  different  logistical were  density  and t h i s  either  and  3b  (df=3,72 p<.001) groups.  approximately levels  3a  Fish 1  fish/1  poorly. Fish  0.14  from  from  f / 1 (9 gm/1)  or  1 24  Figure  14. Plasma sodium c o n c e n t r a t i o n s f o l l o w i n g s a l t water challenge test. P a r t A- s o d i u m c o n c e n t r a t i o n s a g a i n s t r e a r i n g d e n s i t y , p a r t B- s o d i u m c o n c e n t r a t i o n s a g a i n s t tank volume. . V e r t i c a l bars are standard errors. The d a s h e d h o r i z o n t a l l i n e i s an a r b i t r a r y c u t - o f f value. P l a s m a s o d i u m v a l u e s a b o v e t h i s l e v e l a f t e r 24 h o u r s , i n d i c a t e t h a t t e s t f i s h were i n c o m p l e t e l y s m o l t e d , and not f u l l y c a p a b l e of s u r v i v i n g i n s a l t water.  115  190  T  180+ o  ° si  Cl  ^ 170-r-  UJ  i  o CO  i  160+  oo 150 0. 0  DENSITY  190  B  cc  0.9  0.6  0.3  (FISH  1.2  PER LITRE)  T  180+  c__> CD  S 170-1" O OO  f  i  160+ OO  150 200  400  ^o" VOLUME  (LITRES)  500  600  1 26  T a b l e 23. Design of salt water c h a l l e n g e t e s t . Fish from replicate tanks were pooled. The d e n s i t i e s g i v e n a r e t h e actual rearing densities experienced prior to testing ( i . e . m o r t a l i t i e s and sampled f i s h a r e a c c o u n t e d f o r ) .  NUMBER REARING TANKS SAMPLED per tank fish/1  OUP  10 5 10 10 10 10  1 1,4 2 2,3,5,6 3 7,10 4 8,11 5 13,14 6 15,16  0.45  ! by  The  effect  comparing  To  compared. (df=3,77  two  in their  volume  10 1 0 10 1.0 1 4 14  58.3 56.5 66.4 51 .6 56.9 52.9  capacity  and  (df=1,59  containing  15.1 11.5 12.7 9.2 14.7 10.3  regulated  was  examined  experiment  3c.  No  p=.21). but constant, photoperiods  of hyperosmoregulatory  similar  differences  regulation  from  i f the d i f f e r e n t ,  the development  No  on s a l t  treatments  found  determine  treatments  densities  due  to  from  capability,  t h e two rooms  photoperiod  were  were  detected  i n each  treatment  p=.12).  Since  t h e mean  i t was  correlated since  59.6 5.6 21.0 53.0 46.5 52.8  similar  of tank  the  were  affected  varied,  were  MEAN STD. P H O T O P E R I O D WEIGHT DEV. gm gm hours light  well.  differences  had  gm/1  1.01 0.10 0.41 0.96 0.93 0.96  f / 1 ( 3 0 gm/1)  sodium  DENSITY  size  desirable  with  calculated  of  mean  f o r each  significantly  fish  to determine  plasma  smoltification  regressions  of the t e s t  sodium  i s  levels.  weight  treatment.  different  i f individual  modified  fish  from  by  This fish  against  In most zero.  used  cases, In  one  was  weights not  size.  plasma slopes case,  were  unlikely Linear  sodium  were  were  not  however, a  127  significant case  was  the  was  about  sodium  levels,  There  was  plasma  sodium  results  plasma  slope  isolated,  treatment mean  negative  and  because  the  i t s effect  some  concern This  of comparisons levels  was  that  fish  Since  weight  groups  of  this i n the  comparable  ignored. tank  volumes  was c o n s i d e r e d of treatments  against  obtained.  mean  t h e same a s i n o t h e r  levels.  sodium  ( b = - 0 . 3 9 ) was  volume  may  have  unlikely  in  from  (Figure  study  affected view  of  3c. P l o t s  14b) r e i n f o r c e  of  this  conclusion.  Conclusions  Experiment  3a  Growth over  slope  an 8 - f o l d  rate  did  showed  data  range  not  from  affect  evidence  showed 0.5  no  evidence  t o 3.8  growth.  Growth  of a n o n - s i g n i f i c a n t  times  of  density  hatchery  slopes,  effects  levels.  initially  Flow  erratic,  increase during  the l a s t  3  less  in previous  periods. Proximate experiments.  composition Fish  from  moisture  and ash l e v e l s .  content  was  was  the s i g n i f i c a n t  near  density. studies,  These  findings  and t o others  There Cortisol  not a f f e c t e d  were  no  data  were  the high  density  Protein content by t r e a t m e n t s level  treatment-related  concentrations,  was  however,  had e l e v a t e d  unaffected.  although was  to those  i n the  than  treatment  and content  are similar  reported  clear  Lipid  the p r o b a b i l i t y  reduced from  at  high  the f i r s t  two  literature. differences  there  was  a  in  plasma  reduction  with  128  time. Condition  factors  the growth  showed  As  with  and  a pattern mirroring Neither  by  either  density  was  total  activity  On  Experiment  to  were  apparent  3.6  however,  so f o r  significant  observed. significantly  f o r some  net  from  were  that  isolated  was  In  until  cases).  significant for  activity.  d a y 31  affected  a l l  i t peaked  tanks  a t day  declined.  four  on  times  information  any  during  from  3a  of  densities  the high  data.  study  halved  volume  were  found.  (i.e.  densities  doubled  density  growth  depression.  3  from  in  and t h e h i g h  - 0.6  which  tanks  -  f / 1 ) were  3a, t h e r e  This  clearly  was  effects slope remained  treatment  of  from  conditioning were with  in  evidence  with of  was  doubled tanks  growth  volumes  compared  suggests  from  growth  volumes  compared  i n which  study  Density  density  no  with the  extended  Using  differences  when 1.0  range  volumes  f / 1 ) were  were  tested,  which  possibility  in  there  densities.  intervals.  ( 0 . 6 f / 1 ) , no  However,  similar  The d e n s i t y  hatchery  the  tanks  intervals variables  treatment  controls,  When  the  the last the  this  as  sampling  standard  from  explored.  at  time,  of the a c t i v i t y  1.8  unchanged  (except  levels  the f i r s t  effects  exception  were  time  effects.  3b  During  (i.e.  date  s l o p e s was  activity  steadily  of treatment  with  flow  and n e a r l y  the last  study  or  increased  density  growth  a pattern with  activity  differences  net nor t o t a l  There  59.  data,  no e v i d e n c e  were  held slope  halved  tanks  of  significant  the p o s s i b i l i t y  of a  129  conditioning second  effect.  comparison  necessary  to  No v o l u m e in  study  compared  effect  was  3 a , i t was twice  different these  of  similar  found.  When  differences  the  first  Tanks  of  a  before, which  levels  stress  showed first  effect  treatments sampling  being  was  proximate  analysed  treatments  different  were  changed.  was  Since  examined t h e range  compared  between  unimportant.  composition  prior  by s e p a r a t e  sampling  since  the  a n d o n e week  than  were  before  to  the  present  differences sampling  densities  .dates  were  i n which  were  doubled,  compared,  i n the second levels  period  decreased  were  were  densities  those  changed. higher  indicative were  increase.  reduced When t h e  a l l evidence was  when  detected.  had s i g n i f i c a n t l y  (non-significant)  dates  were  volumes  doubled  dates  d e t e c t e d . However,  after,  Tanks  of a s l i g h t sampling  were  compared,  densities  Cortisol  gone.  significantly  of the In a l l  by t h e l a s t  time.  Condition patterns  groups  of flow  were  response.  evidence and l a s t  stress  between  expected  in  Cortisol  data  two p e r i o d s were  immediately  but  changes.  Cortisol  was  the  i t was  results.  of flow  of  d i d not a f f e c t  no  This  the effect  this  affect  volumes  that  3a a n d 3 b , t h e e f f e c t  When  not  densities when  for  and flows,  t o be n o n - s i g n i f i c a n t .  studies  of volume  volumes  found  was  time  as standards  did  f o r the period  tested  Density  used  that  treatments  were  the tanks  contained  establish  Consequently volumes  Since  with  significant  data  were  time  tended  interaction  unaffected  term  to  by  follow  (df=8,1499  treatment. those  for  p<.00l)  Overall growth.  A  demonstrated  1 30  that  sudden  body  changes  in  behavioral  measures,  were  times  pooled,  were  density  (low  significantly  not a  measureable  levels  adjusted  very  have  a  artifacts  of  Exper iment  The trend  quickly.  lasting tank  changes  in  pattern  activity  under  d e n s i t i e s were  This  suggests The  times,  emerged.  both  obtained  effect.  of  volume  related  low  volume  tanks a  this  study  growth  no  growth  individual  activity when a l l  Under  high  measures  were  low  density  (high  changed  activity  levels  that  prior  responses  experience  observed  may  did  have  been  volumes.  reduced  followed  at  total  3c  results  for  clear  conditions  c o n d i t i o n s . When  not  particularly  consistent  volume) below  data,  always  volume)  at  low  effects had  pattern  on  were  volumes  time  A  was  proximate  reduced  with  mixed.  nearly detected.  There  were  Fish  from  composition.  conditions. which  significant  Condition  approximated  the  factors  pattern  in  slopes.  In  apparent  reared  Cortisol  c o n t r a d i c t i o n with  at  levels.  decreased  high As  with  qualitative  consistently  densities  were  a  of  function  volumes  higher  similar,  volume.  growth  had  in experiments  significantly  Periodic was  caused  form. Although  fish  density  time  3a  condition  data,  c o n s i s t e n t l y higher  plasma  and  3b  i n a l l but  observations in  and  the  i t appears  one  Cortisol tank.  indicated that  high likely  volume that  levels  tanks. the  activity Since  response  was  131  Salt  Water  detected  attributed  salt  The  stress-related  attributable  effects.  Challenge:  to  balance  fish reared well  densities).  Fish  evidence  a  of  size, at  reared  marked  flow  rate,  d e n s i t i e s as  (as  well at  water  differences  r e a r i n g c o n d i t i o n s . The  to  Fish  salt  as  high  reduction  high fish  challenge  in results volume, as  30  reared  densities  (60  in osmoregulatory  smolt  test fitness  could  not  be  or  photoperiod  gm/1  regulated  at  much  gm/1.)  lower showed  performance.  1 32  GENERAL The  stress-related  periods  of  high  investigated al.  (1981)  They  found  reduced  this  reduced  the  and  interrenal  nuclear  growth  found  gm/1  17,  part  of  this  objective,  their  effects.  responses  also  or  This  rise  in  typical  of  returned Growth  the  size  to  normal  than  the  under  were  not  were  of  not  fed  contributed  to  (1976)  examined  i n both  coho from  a  few  and 8.5  exhibited and  weeks.  examined  in This  during  densities tested  were  densities. rearing  various the  were  transitory  within  in  hatchery  increased  was  higher  rearing  consequences  ranges  density  glucose  nuclear  fish  gm/1., a l l g r o u p s  responses  Furthermore  transport  examined  blood  have  crowding  102,  204  density  normal  Wedemeyer  to  high  investigations  followed i t may  had  levels.  study,  68,  more  to  thorough  34,  stress period.  responses  few  high  moisture  interrenal  d e n s i t i e s were  levels  three  increased  by  densities  the  when  adaptation.  of  from  body  diameter.  suppressed  elevated  et  growth,  high  that  that  trout  for  stress  and  I  the  Although  steelhead  suggests  of  was  in  and  selected  density-induced  groups  reared  levels  fish  desired  hyperglycemia.  condition  fish  lipid  i s one  short-term  most  body  significantly  rations.  to  and  However,  observed  the  factor,  addition,  a  Fagerlund  condition  This  practices,  salmon on  small  area.  coho  extended thoroughly  densities  had  diameters.  been  of  whole-body  treatments  not  effects  In  Furthermore,  In  have  of  the  that  densities.  rearing  salmonids.  examined  composition,  p h y s i o l o g i c a l consequences  density  in  DISCUSSION  juvenile  density  same  in each  steelhead  regimes. of  the  The three  133  experiments.  Therefore  generalizations  not  made,  for  easily  separately.  Stress  Where  steelhead rearing high  of  in  trout  similar  As  effects,  observed.  first  (2-16  temperature  grams)  described (15°C)  although  However  the  Perhaps  at  or  responses  then  more  consequences could two  not  be  density  lower  time  to  are  discussed  attempted.  be  may  statistically  be  to  in  have  temperatures to  required The  differences  small  effects  at  c l e a r . At  12.5°C,  significant,  the  observed  density are  were  patterns  for  certain  different in  those  tolerances  related  to  may  be  metabolic  physiological  density  swimming  by the  e f f e c t s s i m i l a r to  density  manifested.  ascribed  density  statistically  did  that  physiologically affected  consistency  at  rate,  are  is  demonstrated  earlier,  not  that  if  are  were  suggest  higher,  experiment  generalizations  experiment  strongly 15°C.  each  response  fry  the  density.  clarity,  appropriate,  responses  Results  and  regarding  responses  activity  at  the  temperatures. Growth  short there Such  period were  no  short  literature described  density  were  (less longer  than  2  by  density  weeks).  statistical  during  After  differences  term  density  effects  are  prior  to  Recently  however,  1981.  with  chinook  e f f e c t s should  that  affected  similar short-duration  experiments  found  rates  both  coho  not  and  density  salmon. be  the  adapt  Birks  effects the  (as  initial few  et on  short  in  a l .  the  (1981)  growth  in  duration  of  Wedemeyer  measured  weeks  treatments.  mentioned  surprising, since  steelhead  first  between  not  Perhaps  an  by  (1976) 2  blood  134  variables) Schreck  to  high  (1981)  densities  pointed  Cortisol  l e v e l s ) to  crowding)  can  resulting then  my  occur  from  results  Figures  1,2).  growth  high  et et  The  absence  between  effects points  out,  of some  adaptation  under  and  (1968)  Fromm  elevations  in  Unfortunately  few  crowding chronic  stress  a l .  of  density  effects  of  (Table  et  a l .  4,  1981;  1976;  1971).  differences  Refstie  None  to  of  indicate  However,  chronic  that  i n plasma  have  have  some  Schreck to  the  conditions.  behavioral  as  (1980)  handling  conditioned  Cortisol  that  density  Schreck  (1981)  Cortisol  show  s t r e s s . Furthermore  for  followed  as  plasma  corticosteroids  involve  high  a l .  stress,  density-induced  Kittleson  et  growth  of  response  of  including  reduced  demonstrated  including  hatchery  response  (not  indicative  stress  appears  observed  and  ( i n terms  growth.  conditions  under  If  (Fagerlund  duration.  studies  stress  is  R e f s t i e and  indicators  including  the  have  in  short  become  the  clear  Furthermore,  adaptation  (1-3).  rearing  significant  can  as  weeks  Andrews  changes  salmonids  If,  1981;  plasma  Ejike  stress  a  weeks.  chronic  hatcheries  1976;  stress could  mechanisms. alters  in  treatments  were  few  authors  a l .  temporal  of  density  demonstrate  examined  levels  a  2-3  complete  types  within  suppression  Brauhn  that  some  Many  Trzebiatowski 1977;  out  within  to  of  are  Also, well  stress  transitory.  Cortisol  noted in  forms  Hill  response  adaptation  to to  as p h y s i o l o g i c a l that  conditioning  salmonids.  other  types  Possibly of  stress,  rearing.  Cortisol  data  density-induced  suggests, stress  complete  had  occurred  recovery by  the  from end  of  135  the to  experiment, growth  state  slope  (and  the  also  data,  Both  induced  stress  that  and  protein  al.  (1981)  also  reductions  in  reductions that for  with  assuming  and  in protein  75%  fingerlings. reductions high  clear  lipid  in  the  according  indicators  of  metabolic  and  This  Furthermore  rearing  (activity).  not  well  not  density exact  indicators i n terms  understood. produced  and  data  The  etc.),  densities  fish,  was  condition factor  condition,  rearing  thus  i n d e n s i t y were  and  content reserves and  of of  However measurable  altered  moisture) and  tissue  high  could  densities.  in  Noakes  responses  lipid in of  in  for  (1977)  (32%  and  of  and  Laycock  is associated  dry  Li  (1977)  (1969)  body of  (1973)  rainbow  trout  capabilities  Burrows  survival  Leatherland  rainbow  suggest  metabolism  8%  and  They  Lee  mammals.  et  towards  reduced  avoidance.  subordinate and  Fagerlund  trend  densities.  signify  optimal  Brocksen  moisture  elevations in moisture  at  reserves  levels  content.  non-significant  predator  are  elevated  a  impaired  lipid  in lipid  significant  corticosteroids  Li  so  physiological  are  the  or  differences.  behavior  reductions  that  in lipid  stress  in  increases  lipid  that  no  effects.  in  observed  elevated  suggested  at  with  observed  show  fitness,  sustained activity  (1978)  other  week  metabolism.  levels  reduced  first  composition  different  energy  and  the  composition,  changes  Associated  of  various  differences  ultimate  physiological  end  should  changes  of  and  is clear  growth  then  density  (proximate  survival  the  proximate  persistent  consequences  it  by  stress) also  case.  reflect  and  weight  released observed  trout  reared  demonstrated  associated  with  136  heirarchies  and  found  studies  suggest  that  density  rearing  may  The  the  significance i s obscure.  negative  nitrogen  w a s t i n g -(Lee starving  case.  In  appears This  that  reduced  1978).  crowded  contributed though  lipid  to  food  of and a  a l .  this  to  but  be  and  may  high  mammals to  be  excess  storage  a  muscle  adaptive  comprehend  is  in  this  food,  i t  reduced.  r e l a t i v e increase  provided  growth  Li  high  at  lead  with  energy  may  in  can  response  observed  1981;  levels  stress  the  and  These  accompany  protein  conditions  conversion et  Such  reserves.  which  i t is difficult  e f f i c i e n c y of  food  lipid  survival.  cases  develops  under  (Fagerlund  in  excess  at  efficiencies  Brocksen  1977;  in high  may  be  Andrews  et  1971). High  increased  fish.  condition physical  hatcheries The  as  a  factor  condition  (1977)  this  range  condition later,  of  i s that  have In  decreased  (subordinates). density  means  factor.  noted  attributed  factors  f i t n e s s and  assumption  condition low  severe  balance  Even  of  increased  but  have  densities,  In  Laycock  the  protein.  of  in  changes  chances  animals  fish,  may  body  al.  and  reflected  tissue  reduce  densities  in  this  to  Fagerlund  differences  are  routinely the  fish  given  greater  of  in  months a l . coho  significant differences  at  of  salmon.  high  of  fish  the high  with  by  small over  no  a  four  He  fish 2-fold  evidence  Condition  a  Refstie  densities.  However,  found.  most  a  excess  rearing found  in  with  than  to  with  health  length  intake  (1981)  were  calculated  general  fed  factors  food  associated  reserves  trout  condition  et  a  energy  rainbow  six  sometimes  assessing  reduced  After  are  of  months factors  137  were  lower  reduced food the  at  rations  may  growth  for  and  even  body  conditions  reserves.  Density  the f i r s t  Interpretation the  observed  temperatures, of  density.  greatest This  a per  both  given fish  most time) may  reported reared  in  decreased  the  at high  densities. speculative.  densities  High  first  reduced a t Growth  correlated. were  fish  Total  Under  high.  This  increase  energy  were  marked  difficult.  Since  measures  reason  total  net  activity  real  (total  activity  the following levels,  density.  maintained moved  Available are  were  no  l e v e l s of  in  space  studies salmonids  conditions. were  on a g g r e s s i o n  activity  levels  distance  movement. T h e r e  both  consequences  fish  increased.  hatchery  at  at the lowest  density  activity  of  clear  were  of aggression  studies  and  they  lowest  as d e n s i t i e s  under  was  and lowest  the  literature  For this  data  that  limited total  a r e no r e p o r t e d  were  in condition  consistent  likely  at  rigidly.  Quantitative there  were  density  that  have  differences  temperatures,  at the middle  positions  growth  My  rations.  factors  o f good  of the behavior  i t appears  indicates  closely  condition  i n unfavourable  factors  fed excess  were  for  of h e i r a r c h i e s at  population.  were  receiving  period.  patterns  At  the  were  competition  resulted  fish  periods  time  i n turn  condition  related  fish  period,  that  growth  during  last  of  condition  of r a p i d  that  when  Since  t o the development  much  demonstrated  densities,  during  of t h i s  contributed  conditions  suggests  densities.  d e n s i t i e s , and these  experiment  rate  high  f o r much  have  higher  high  the  not c o l l e c t e d , and  in fish  at  discussion combined  hatchery  is entirely  with  precise  1 38  station  maintenance  behavior.  High  activity  short-duration visible  at  the  low  higher  d e n s i t i e s . At  This  could  under  acts  reflect  conditions  This  result  have  area.  been  fish  so  If  the  At  behavior  then  Kawanabe  that  increased.  the  effect  most  were  behavior  territories  be  was  and,  elevated.  time,  intruder  the  decreased.  i s small  may  defence  at  maintenance  defend  rate  were  quantified  estimated  distance  densities,  territorial  not  levels to  in  periodic,  position  neighbour  increase  of  aggression  were  reliably  activity  but  in  a  pressure  may  inhibited,  and  levels  the  position.  low  net  and  the  absence  r e s u l t s agree  of  these  total  activity  or  with  can  active  in  measures,  expended enough,  pulcher,  Energy  no  the  highest  energy  i n A.  growth  differences  the  i f high  reduced such  an  indicate  use  expenditures, found  be  of  territorial  reduction  those  of  of  at  agonistic  Magnuson  (1962)  (1969).  Another of  these  encounter  in  these  acts  attempts  nearest  that  result  density,  total  intruder  relatively  density  estimate  and  indicate  the  Some  not  middle  maintained  highest  and  the  high  passively  could  where  perceived  be  however,  continued  therefore,  localized  may  sequences.  precise,  may  d e n s i t i e s , may  density;  aggressive  least  low  levels  chase  since  was  at  as  expended large  could  rainbow  not  be  trout.  fastest.  obtain  Li  growth.  In  since  Minchen  increased  was  and  a qualitative  activity,  space  swimming  a t t r i b u t e d to  grew  limit  absolute on  to  swimming  containers.  in  fish  in  was  given  Brocksen  my  activity  as  such  (1972)  activity a  cause  (1977)  experiments differences,  of  found growth since  1 39  Although behavior  are  conditions have  affect  strategies  do  could  released  trout  similarly  to  are  As  effect  be  used  in  was  (than  short  (both of  all  of  in  rearing  several  wild  altered  and  authors  hatchery-  hatchery  rearing  the  sudden  changes  prior  in  weight,  Growth  rate,  those were  treatments  this  first  experiment)  a  since the  behavior  questions:  density  growth  conditioning  in density?  fish.  may  be  Perhaps  respond  effects  pattern  effect)  McDonald  et  important  in  prior  first  is  what  al.  on  is  (1968)  determining  experience  also  reactions.  were  that  juvenile  steelhead  physiologically affected  proximate  composition  and  trout, by  condition  15-  rearing factor  view.  treatments not  two  and  experience  in  supported  the  answer  secondly,  r e s u l t s demonstrated  grams  to  i n d i c a t i v e of  physiological  densities  that  earlier,  behavior  duration  influences  In  in  stress;  reactions  data  the  patterns  beneficially influence  tested  behavioral  density.  noted  designed  that  30  demonstrate  Perhaps  to  observed  fingerlings  suggested  The  in  streams.  density of  curvilinear the  behavior.  experiment  larger  growth  do  the  fish.  responses  This  in  of  they  differences  salmonids  Stress  significance  unclear,  described  reared  of  the  high  where  enough  to  were  compared  high  densities,  suppression  at  suppression  suggests  a  volumes elicit  a  were growth  not  response.  there  was  evidence  and  the  degree  threshhold  effect.  In  adjusted  the  of of  When  growth growth  literature,  1 40  evidence  for threshhold density  (1946a)  found  that  intermediate  growth  i n t a n k - r e a r e d brown  rates  in  time, a  the  similar  second to  conditioning  first time  interval.  this  interval  effect  of  was  density  density  response  in  detect  a  volumes  ( i . e .densities)  however, effects  of  and  the  would  be  fish, fish a  a  in tanks less  the  first  compared had  greatest  with  suggest in  the  i n the  response  over  first during  experiment, time.  influence  of  No  the  other  fish  the  in  a  i n which  size  on  That  in  reduction  than  that  of  first  experiment  some  i n growth  other  tanks  no  four  treatment  that  alone.  tanks  doubled,  found the  i n one  density  some  results,  of  greater than  of  were  the  one  after  was  (1946b)  i s , only  densities basis  There  Brown Only  effects,  rates  influenced  studies.  densities  expected  and  densities  large  acclimation  changed.  have  significant.  on  with  (1977)  to changing  or  been  may  their  d o u b l i n g of  resulted  rate  in  expected  comparison,  were  volume  proved  response  again  density  the  Brocksen  volume  comparisons was  rates  tank  Li  to  of  moderating  pattern  and  magnitude  density-conditioning  growth  that  response  Growth  salmonids.  observed  concern  curvilinear  persisted  optimal  fingerlings.  experiment,  Unlike  Brown  produced  were  growth  demonstrated  and  although  effects  smaller. on  fry  i n the  the  densities  first  density  However,  have  To  As  i s rare  followed a  i n the  effect.  studies  trout  study  that  experiment,  effects  which In  this  containing  200  rate.  began with  In  fact,  growing higher  at fish  densities. As  i n the  there  was  no  evidence  of  stress  141  from not  the  Cortisol  surprising  there  evidence chronic  not  in this of  growth  rates.  that  the  stress  reasons  evidence in  Although did  although  was  differences  d a t a . For  use  i s of  indicate  study, at the  of  This plasma  stress  while  less  pronounced  show  similar  t r e n d s . The  the e f f e c t s  relative  change  experiment. juvenile density  of  With  important  source in  than  between  significant  differences  the  first  experiment.  In a d d i t i o n ,  body  observed  in  condition  factor  of  the  the w e l l - b e i n g  trend  was  condition first  may  not  of  which  of  was  The  metabolism,  i t  the  are  smaller  first  growth These  slopes findings  p r o v i d e an fish.  clear  first that  the  to  most  compromised.  of body c o n d i t i o n  t h e r e w e r e no  due  similarly  reserves,  the  did  appears  respond  exercise,  and  effects,  o c c u r r e d i n the  lipid  in  probably  also  between d e n s i t i e s  or  always  changes  experiment,  results and  indicator,  to  density  experiment. were  found  i n the o p p o s i t e d i r e c t i o n  study.  of a group  further  indicator  were  first  grams),  second  experiment,  in" e i t h e r  that  response  the  an  indicator.  changes,  for sustained  this  time  clear  (2-30  the  sampling,  stress  there  the  Under h i g h d e n s i t i e s  Differences  Although  of  respect to energy  energy  were o b s e r v e d  lack  trout  was  stress-related  as  level  level  of  sudden d e n s i t y  steelhead stress.  those  i n weight  of  provides  Cortisol  response,  composition, a tertiary than  this  value.  proximate  to  finding  Cortisol, a primary  a  time  density-induced,  limited  plasma  described earlier  to  in the  patterns with as  had  been  suggest  that  accurate  assessment  142  Stress  responses  i n smolts  Interpretation experiments  of  and  responses  smoltification.  Table  occur  during  assess  stress  smolt.  In p a r t i c u l a r ,  and  tend  Dickhoff  1976a;  complex. levels  of  showed  to  three  times  findings  principle,  there  treatments.  that have  of  of  normal  been  some  the  factor  and  growth  In  medium  growth  changes  variables  rates  from  to  parr to  body  the  by  that  used  increase  increases  of  moderated  whole  addition,  group  lipid (Folmar  capacity  to  (Komourjdian  et  small-scale  experiment  condition factors,  differences body  in  stress  composition  and  (3a)  were  and plasma  Cortisol  response  between  hyper-osmoregulatory  otherwise. reared  i n growth  size)  over  an e i g h t - f o l d  rates.  This  suggests  a r e u n a f f e c t e d by r e a r i n g  conventional i n the fish findings  hatchery culture  agree  levels.  literature;  with  density  those  that  range larger  densities There  up  a r e no  however,  o f Kawanabe  in  (1969)  (1962).  Cortisol However,  first  grams)  these  Magnuson  a list  whereas  1976).  rates,  suggested  smolt  fact  final  the transformation  condition  However,  (near  during  the  1974a).  no  (30-60  the  Some  hypertonic  no d i f f e r e n c e s  similar  and  a  of  t o d e n s i t y may  change  the  suggested  Trout  by  to decrease,  Growth  capability  trout  also  Wagner  treatments.  results  smoltification.  in  Results  presmolts  13 p r o v i d e s  1980; H o a r  osmoregulate al.  the  was c o m p l i c a t e d  processes  content  and  levels  were  unaffected  was a d e c l i n e w i t h  If fish  were  time  by  rearing  t o common  stressed, adaptation  may  density.-  levels have  i na l l  occurred.  1 43  If  this  a  time  was  the  case  sensitive  Dickhoff  then, to  rearing  Cortisol  1980),  during  should  the  period  of  stress  (Schreck  not  used  be  smoltification, 1981;  to  Folmar  assess  and  chronic  stress. As not  mentioned  clear.  high  densities.  showed  a  (1981),  density.  are  in  If  content  Komourdjian  high  at  stress-related  as  must  used  be  readiness  or  stress  the  significance imply  density. rates  This  are  levels  with  the  does  data  Burrows  lipid  if  are  or°  response near  the  changes suggests  inadequate  as  indicate  Markert be  attributed  Clearly,  indicator  body  composition  of  to  certain stress.  of  of  in  lipids  either  smolt  especially Although  is unclear, with  et  a  survival  conditions Birks  1976;  either  smoltification.  associated  in  Therefore,  smolt  experiments,  altered  indicators  ability  state  trends  of  under  two with  (Hoar  1968).  time  that  et  Reductions  that  metabolism  These  first  reduced  found  in density  lipids  increase  advanced  an  at  stress.  the  in  my  more  increased.  caution  taken of  (1969)  and  smoltification  could a  of  difficult.  and  higher  Fagerlund  not  caused  with  densities  of  did  levels  is  were  increased.  those  levels  Vanstone  reduction,  those  rearing  p a t t e r n s were  unaffected,  from  data  content  density  with  associated  high  smoltification. increased  lipid  a l . 1976b;  levels  as  moisture  density  of  are  et  decline  protein  increased then  were  different  that  composition  moisture  levels  to  Interpretation  reduced  and  ash  favourably  but  survive,  lipid  both  Protein  compare  experiments  to  proximate  tendency  findings al.  However,  earlier,  a l .  i t  rearing growth (1981),  1 44  studying In  growth  density  After  had  in  the  did  proximate  condition  describe  1976a;  analysis  reduction  1974b;  in condition  assessing  smolt  manifested  in changes  therefore  appear  stress  under  assessing indicate water  not was  be  sharply been  in  were  were  to  changes  Many  authors  Wagner  the  e f f e c t s of  value  during et  as  a  Furthermore, limited  stress  in  my  yet  means  of  were  not  data,  means  of  and  assessing  their  since  a l .  considered  satisfactory  factor  As  the  Komourdjian  Indeed,  streamlining,  rates.  streamlining)  a  limited  high  effects.  growth  difficult.  1980;  condition  Energy  value  in  did  not  they  differences  It  day  31  seems the  However,  earlier, to  differences  expenditure  activity.  described  from  with  is  treatment-related  attributed  associated  Clearly  free  at  density  be  appears  levels.  declined.  to  be  in  salt  detected.  no  activity  of  (increased  conditions.  differences  evenly  of  status  i n t e r e s t i n g . As  increased  in be  these  readiness  total  to  smolt  There or  status.  reared  i n t e r p r e t a t i o n of  1976).  factors  to  stress  been  s i m i l a r to  Dickhoff  Hoar  suppression  capability.  period  in condition and  had  evidence  data,  conclusions.  apparently  which  pattern  this  (Folmar  Wagner  a  no  similar  growth  of  fish  showed  during  smoltification  found  months  follow  reductions  reached  osmoregulatory  factors  they  they  growth)  reduced  Condition However,  salmon,  several  ( i . e . equal  densities  with  chinook  experiments,  short-lived. growth  of  day  59  probable  process  of  (3 that  either  differences the  both  in  pattern  measures  of  intervals), the  increase  smoltification.  net  could  with  time  activity and  then  may  have  Several  1 45  reviews  (Wedemeyer  et  Dickhoff  1980),  increases in  associated the  note  tendancy  increased  period  of  (1965)  and  Wagner is  The  to  of  arbitrary  are  considered  efficiently  165  less  the  (average  data  were  the  and  part  equally  may  an  Conte  If  of  the  prepared.  indicate  smolt  and  increases.  is a  that  and  the  Wagner  transformation in  after  Blackburn  surviving  180  meq/1),  suggests  that  of  densities  results had  proximate  rate  when  and  the  ability  sodium  levels  above  the  but  still  below  this  level  fish  water.  sodium that  from  not  Fish  from  levels  less  high  density  are  a  study  or  were  slight  Until  either  growth  Cortisol.  insensitive  changed,  responded  (3b)  3a.  plasma  relatively  volumes  doubled  experiment  affected  analysis,  fish  were  plasma  small-scale  density  However,  i n sea  suggested  stress.  the  large  1978)  indicating  second of  in  slightly  meq/1. A b o v e  regulated  test  plasma  hours,  of  some  growth  and  24  capable  This  in  densities,  170  changed,  densities.  effects,  of  factor,  where  low  challenge  value  the  in part,  water  At  (Clarke  condition  decrease  my  Folmar  smolts  also  passed.  treatment  meq/1  rate,  tanks  that  of  urge  date  to  some d e g r e e of  were  rearing  last  salt  treatments  Results  volumes  of  cut-off  imposed  confirmed,  the  noted  survive.  density  rearing  (1974b)  150-160  the  high  in  r e a d i n e s s had  attributable  regulated to  optimum  activity  a l l groups  on  1981b;  transient.  differences,  were  then  smolt  results  smolts  Schreck  observed  in activity  optimum  steelhead  of  process,  decline  1981;  school. Migratory  activity  smoltification The  to  a l .  with  reduction  fish  to in  a  marked  in  body  1 46  condition. on  the  were  The  basis  halved  These  decrease  did  reductions  density  not  show  space  than  reductions  in  space  and  Changes  in Cortisol  changes,  (1981)  had  to  useful  not  supported  by  Cortisol temporal a  sampling which  to  trend.  levels  In activity likely  lack  after do  adapt  the and  was  plasma  Cortisol  at  on  experiment  3a  treatment  levels.  statistically week by  after  Schreck  levels least  appear  one  week  interpretation  day  74  is  providing  weeks  at  the in  not  of  last growth  indicate  are  the  evidence  differences  adjustment, few  confirmed  effects  significant  a  from  (1976).  collected  after  sudden  evident  Cortisol  This  more  That  described  for  sudden  are  c o l l e c t e d one  stress  their  that  although  as  tested.  to  density)  stress  plasma  volume  and  fish.  Wedemeyer  the  densities  variables  per  stress.  of  where  expected  that  sensitive  stress.  view  of  over  the  eight-fold density  the  activity  that  artifacts  The  in  despite  persisted  chronic  of  in  were  chronic  measurements  date,  Cortisol  samples  the  observed  the  small  Therefore  of  of  from  adaptation  findings  decline  seasonal  and  i n d i c a t o r s of  tanks  than  "conditioned"  space  data  occurred.  in  (increases  were  greater  density,  caused  perfect  the  become  fish  plasma  imposition  i n any  in  levels  Since  volume  the  per  was  Fish  rearing fish  condition  significant.  after  fish  increases  growth  be  changes  that  per  rate  alone.  including  in  stressful  growth  of  r e s u l t s suggest  environment,  in  of  the  volume  absence  of  significant range  differences  d i f f e r e n c e s . At  low  in  differences  study  observed  in  densities  3a, study  (high  i t 3b  in is  were  volumes)  147  both at  net  the  and  total  high  activity  density  experiment  3a  (1972)  volume  increased.  found  range  activity  study  that  consistently  However,  the  here. as  volumes  in  Furthermore rearing  observations  (different  increased  than  range  absolute  qualitative 3c  higher  density  tested  increased  addition,  in  suggests  the  that In  levels  densities),  volume).  bracketed  Minchen  activity  (low  l e v e l s were  volumes,  induced  on equal  increased  activity. Only  two  challenge: which time  either  the  These  test,  had  et  a l .  rearing  effect and  on  Brocksen  of  the  (1977) and i t  other  water  tolerance.  those  Those  of  exposed fish  salt  and  to  those  reared  3a  in  at  the  densities at  osmoregulatory  experiment  water  Therefore,  the  of  lower  performance.  and  small-scale  experiment  a  though  This  slight, is  Brown  studies.  cycle)  were  from  cycle),  differences  in  (1946a). that  the  experiments  photoperiod  salt  volume  from  had  results  the  no  and  3b  tolerance  findings  the  trend  were  of  was  influenced  effect  reared  3c  on  not the salt  similar  photoperiod  detected.  unimportant.  Li  (14L:1OD  under  (10L:14D were  indicated  significant,  experiment fish  effects  to  effects  with  3a  (3c)  not  Because  volume  fish  compared  in  contrast  Rearing  When  densities  that  the  unchanged,  been  better  is unlikely  of  indicates  fish/1.  had  rate.  results  no  recently  third  volumes  significant,  were  in  (1981).  growth  photoperiod  had  with  tested  (densities doubled).  1.0-1.1  agree  Results that  or  volumes  halved fish  were  significantly  finding  Birks  in which  were  0.5-0.6  density  of  those  volumes of  treatments  Fish  This reared  148  at  low  volumes  tended than  to  grow  fish In  reared  on  studies  produced  trout  as  a  it  degree  in  understand  the  hatchery  of  reasonable hatcheries  by  mechanisms  by  production  and  fundamental  physiological  levels  behavior,  induced is  conditioning "adverse"  far  is  changes from  effect  effects  clear. is  of  100%.  survival  body  high  of  at  of  high of  the often  none  an  trout  of  or the  accurate  by  steelhead  the  rearing  culture  the  Lastly,  densities  the the  appear  be  basis,  increase  rearing  to  fully  induced  stress  released  fish,  behavioral  significance  composition,  may  managed  However,  both  Furthermore,  unclear.  at  intensity  that  that  density  research  in  the  most  duration  the  carefully  which  The  some o r  experienced  experimentally  required.  of  rearing,  a  to  each  provide  steelhead  50  rearing  variables  either  suggest  On  they  levels  of  reared  is clear  density  to  from  Different  stress  necessary.  In  apparent  It  for  Cortisol  size.  fish  the  results  additional,  density  high  hatcheries than  some  in  alone,  of  Although  consequences  regarding  used  these  in  plasma  evidence  response.  when  appear  densities  affects  conclusions  factors.  fish  experiments.  the  conservative would  was  and  the  used  there  with  nature  consequence  densities  vary  the  Practically,  more  trout  stress  of  of  volumes.  of  tested,  assessment  high  tested,  different  variables  lower  stress-related  between  duration  had  here,  Both  varied  condition  they  the  described  densities.  the  under  steelhead  variables  stress  reduced  slower,  summary,  density  the  had  and  to  fish  of  growth  rate,  and  nature rate as  at  of which  the the  densities  1 49 increase,  and  knowledge  could  disappear have  as they  considerable  decrease management  i s unknown, value.  yet  this  1 50  REFERENCES  Allen,  CITED  K.R. 1 9 6 9 . 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R a t i o n a l d e s i g n o f hatcheries f o r i n t e n s i v e s a l m o n i d c u l t u r e , b a s e d on m e t a b o l i c c h a r a c t e r i s t i c s . Prog. F i s h C u l t . 39:157-165.  W i n d e l l , J . T . , D.O. N o r r i s , J . K . K i t c h e l l , a n d J . S . N o r r i s . 1969. D i g e s t i v e response of rainbow t r o u t , Salmo g a i r d n e r i , t o p e l l e t d i e t s . J . F i s h . R e s . B o a r d Can. 26: 1801-1812.  Z e l n i k , P.R. a n d G. G o l d s p i n k . 1 9 8 0 . E f f e c t s o f e x e r c i s e a t d i f f e r e n t swimming s p e e d s on b l o o d C o r t i s o l l e v e l s i n t h e rainbow t r o u t , Salmo g a i r d n e r i R i c h a r d s o n . A b s t r a c t In, A.D. P i c k e r i n g [ed.] S t r e s s and f i s h . Academic Press. Toronto.  161  APPENDIX  I.  A N A L Y T I C A L COMPOSITION  OF  ARTIFICAL  SEA  SALT.  Average s o l u t i o n of Forty Fathoms Marinemix hydrated to a density of 1.025 using d i s t i l l e d water. F i g u r e s c i t e d from a c t u a l independant laboratory analysis. Concentratioins in p a r t s p e r m i l l i o n (ppm). U p o n h y d r a t i o n , pH i s 8 . 3 .  aluminum 0.06 antimony 0.0005 argon trace arsenum 0.01 barium 0.12 b i c a r b o n a t e . . . . 174 beryllium 0.0002 bismuth trace boron 2.1 bromide 62 cadmium 0.009 calcium 410 carbonate 10 cerium 0.0007 cesium trace chromium 0.02 chloride 18600 copper 0.007 cobalt 0.0025 dysprosium trace erbium trace europium trace fluoride 1.9 g a d o l i n i u m ....... t r a c e gallium 0.0004 germanium 0.00005 gold trace hafnium trace helium trace holmium trace indium trace iodine 0.03 iron 0.03 krypton trace lanthanum trace lead . trace lithium 0.24 lutetium trace magnesium 1290  manganese mercury molybdenum neodymium neon nickel niobium nitrogen palladium phosphorus potassium praeseodymium protactinium radium radon rubidium ruthenium samarium scandium selenium silicon sodium strontium sulfur (sulfate) tantalium tellurium terbium thalium thulium tin titanium tungsten uranium vanadium xenon ytterbium yttrium zinc zirconium  0.008 0.0007 0.005 trace trace 0.009 trace 0.85 trace 0.04 380 trace trace trace trace 0.06 trace trace trace trace 4.5 10400 12.4 2600 trace trace trace 0.00007 trace 0.006 0.004 0.004 0.00005 0.0009 trace trace trace 0.24 trace  

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