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Downstream migratory behavior of sockeye salmon fry, with particular reference to predation Delaney, Peter Wayne 1979

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DOWNSTBEAM MIGEATOBY BEHAVIOE OF SOCKEYE SALMON FE WITH PAETICOLAB EEFEEENCE TO PEEBATION by PETEE WAYNE DELANEY B . S c , U n i v e r s i t y o f B r i t i s h Columbia, 1972 A THESIS SUBMITTED IN PABTIAL FULFILLMENT OF THE EEQUIEEMENTS FOE THE DEGEEE OF MASTEE OF SCIENCE i n THE FACULTY OF GEADUATE STUDIES (Dept. of Zoology) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVEBSITY OF BEITISH COLUMBIA Sept, 1979 ^c) Peter Wayne Delaney, 1979 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 :-6 B P 7 5-5 1 I E ABSTBACT Various aspects of downstream migratory behavior of sockeye salmon f r y (pncorhynchus nerka) were examined i n a s e r i e s of f i e l d and l a b o r a t o r y experiments. The f i e l d work at the Department of t i e Environment ( F i s h e r i e s and Marine S e r v i c e ) F u l t o n E i v e r spawning channels, Babine Lake, B r i t i s h Columbia, was concerned with the p r e d a t i o n by rainbow t r o u t (Salmo  g a i r d n e r i ) and w h i t e f i s h (Prosopium w i l l i a m s o n i ) on sockeye f r y with v a r i o u s kinds of p r i o r e x p e r i e n c e . The l a b o r a t o r y s t u d i e s focused on the e f f e c t s of exposure to l i g h t on the behavior of emerging and r e c e n t l y emerged f r y . The r e s u l t s showed t h a t : (1) the number of f r y moving downstream v a r i e s throughout the n i g h t l y m i g r a t i o n p e r i o d ; (2) the presence c f predators m o d i f i e s the movement p a t t e r n o f migrating f r y , such t h a t the f r y tend to move downstream over a more concentrated time p e r i o d ; (3) f r y response to predators tends not t o be predator-sp e c i f i c , m i grating f r y respond s i m i l a r l y t o d i f f e r e n t spec i e s o f p r e d a t o r s ; (4) emergent f r y are not a l l s i m i l a r i n t h e i r migratory behavior, s ome tend to migrate r a p i d l y ( f a s t migrants) , while others migrate at a slower r a t e (slow migrants) ; (5) g e n e r a l l y . f r y with p r i o r experience to pr edators d i s p l a y e d d i f f e r e n t migra t o r y behavior compared to f a s t a nd slow migrants; and (6) subj e c t i n g newly-emerged f r y to i n c r e a s i n g time p e r i o ds of l i g h t treatment and f r y d e n s i t i e s , a l t e r s behavior p a t t e r n s . I t i s concluded t h a t f r y com mencing downstream movement are not a l l s i m i l a r i n t h e i r mi gr a t o r y behavior. Begardless of the b a s i s f o r the b e h a v i o r a l d i f ference i i i between f a s t and slow migrants, the presence of predators m o d i f i e s and enhances downstream movement. F u r t h e r , s u b j e c t i n g premigratory f r y to l i g h t , a l t e r s downstream movement and b e h a v i o r a l i n t e r a c t i o n s between f r y . i v TABLE OF CONTENTS Abstrac t i i T a t l e Of Contents .... .... i v l i s t Of F i g u r e s v i L i s t Of Tables i x L i s t Of Appendices x acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x i i i IN TIC DUCT ION .. 1 SECTION A: EFFECT OF PBEDATOES AND EXPERIENCE CN MIGBATOEY EEHAVIOB 3 M a t e r i a l s And Methods .................................. 3 Experiment 1 - E f f e c t Of D i f f e r e n t Predators On Naive Fry 11 Methods And B e s u l t s ................................. 11 D i s c u s s i o n 15 Experiment 2 - E f f e c t Of D i f f e r e n t Predators Cn Experienced Fry ..................................... 16 i i Methods And B e s u l t s 16 D i s c u s s i o n ............ . ... ........................... 22 Experiment 3 - Comparison Of Experienced And Enumerated Fry .................................................. 26 Methods And B e s u l t s ................................. 26 B i s c u s s i o n 28 SECTION E: EFFECT OF PBEEATOF.S AND LIGHT ON EMEEGING FEY .. 30 M a t e r i a l And Methods 30 V Experiment 1 - E f f e c t Of D i f f e r e n t P r e d a t o r s On,Emerging Fry .. ........... 35 Methods And R e s u l t s ., 35 D i s c u s s i o n ........................................... 43 Experiment 2 - E f f e c t Of D i f f e r e n t P r e dators And L i g h t On Emerging Fry ..................................... 48 Methods And Results' 48 D i s c u s s i o n .......................................... 54 e SECTION' C: DEVELOPMENT OF SCHOOLING BEHAVIOE 57 Experiment 1 - F r y Eesponse To L i g h t ................... 57 M a t e r i a l And Methods ................................ 57 Re s u l t s 58 Experiment 2 - E f f e c t Of L i g h t And Fry D e n s i t i e s On Sch o o l i n g Behavior .................................. 64 M a t e r i a l And Methods ................................ 64 E e s u l t s ............................................. 67 Di s c u s s i o n .... ......................................... 72 DISCUSSION , . 76 A. Summary Of E e s u l t s .................................. 76 E. E a r l y L i f e H i s t o r y Of Sockeye F ry ................... 76 C. S i g n i f i c a n c e Of Predation ........................... 79 E. Migrants And Non-migrants 81 E. The E f f e c t Of Experience ............................ 85 F. The S i g n i f i c a n c e Of Schooling ....................... 89 LITEEATUEE CITED 92 Appendices ................................................ 96 v i LIST OF FIGURES FIGDEE 1a: Geographic l o c a t i o n of Babine Lake and F u l t o n E i v e r . ......................................... 4 FIGUEE 1b: F u l t o n E i v e r and adjacent spawning channels. ... 5 FIGURE 2a: Experimental stream channels; l o o k i n g downstream. .................................... 6 FIGURE 2b: Experimental stream channels; l o o k i n g upstream. 6 FIGUEE 3: Prey-trap at downstream end of experimental channels. ...................................... 7 FIGUEE 4: M i g r a t i o n p a t t e r n s of i n e x p e r i e n c e d f r y w i t h i n experimental stream channels. C a l c u l a t e d frcm the t o t a l number of f r y completing m i g r a t i o n . .. 12 FIGURE 5: M i g r a t i o n p a t t e r n s of i n e x p e r i e n c e d f r y w i t h i n experimental stream channels. C a l c u l a t e d frcm the t o t a l number of f r y s t a r t i n g each experiment. .................................... 12 FIGURE 6: M i g r a t i o n p a t t e r n s of v a r i o u s 'experienced* f r y w i t h i n experimental stream channels; S e c t i o n A, Experiment 2. ............................... ... 19 FIGUEE 7: The e f f e c t of predator presence/absence on percent migrants f o r each spawning channel. .... 19 FIGUEE 8: Summary of r e s u l t s f o r percent migrants i n the f i r s t hour; showing response cf v a r i o u s •experienced' f r y i n d i f f e r e n t predator regimes. , 24 FIGURE 9: M i g r a t i o n p a t t e r n s of v a r i o u s 'experienced' f r y w i t h i n experimental stream channels; S e c t i o n A, Experiment 3. .................................. 24 FIGURE 10: Experimental stream channels d u r i n g second f i e l d season. 31 FIGURE 11a: Prey-trap at downstream end. ................... 32 FIGUEE 11b: P r e y - t r a p i n p o s i t i o n . 32 FIGURE 12: Prey-trap with f r y , on counting t a b l e . .......... 33 FIGURE 13: I n c l i n e d - p l a n e t r a p used f o r c o l l e c t i n g emergent f r y . 33 v i i FIGURE 14: Mean mi g r a t i o n p a t t e r n f o r experimental and nai v e f r y w i t h i n a r t i f i c i a l stream channels; S e c t i o n B, Experiment 1. 36 FIGURE 15: M i g r a t i o n p a t t e r n s of experimental f r y w i t h i n a r t i f i c i a l stream channels. P l o t of 'time p e r i o d s x f r y type' i n t e r a c t i o n . Appendix V. ... 36 FIGURE 16: M i g r a t i o n p a t t e r n s . o f experimental f r y w i t h i n a r t i f i c i a l stream channels, P l c t of 'time p e r i o d s x pr e d a t o r s ' i n t e r a c t i o n . Appendix V. .. 36 FIGURE 17: M i g r a t i o n p a t t e r n s of (a) f a s t migrants, (t) slow migrants, and (c) experienced f r y w i t h i n a r t i f i c i a l stream channels. .................... 38 FIGURE 18: M i g r a t i o n p a t t e r n s of experimental f r y w i t h i n a r t i f i c i a l stream channels c o n t a i n i n g (a) rainbow t r o u t , (b) w h i t e f i s h , (c) rai n b o w / w h i t e f i s h combination, and (d) no pre d a t o r s . .................................. ...40 FIGURE 19: Means o f percent migrants i n the f i r s t hour p l o t t e d f o r (a) f a s t migrants, (b) slow migrants, and (c) experienced f r y mi g r a t i n g w i t h i n each of f o u r predator regimes. .......... 41 FIGURE 20: Means of percent migrants i n the f i r s t hour p l o t t e d f o r experimental f r y migrating w i t h i n a r t i f i c i a l stream channels c o n t a i n i n g (a) rainbow t r o u t , (b) w h i t e f i s h , (c) rainbo-w/whitef i s h combination, and (d) no predators....,,.....,,.,.......,...,,,.....,...... 42 FIGURE 21: Means o f percent (a) migrants, (b) non-migrants, and (c) l o s t or eaten f o r experimental f r y mi g r a t i n g through a r t i f i c i a l stream channels with and without p r e d a t o r s . .................... 44 FIGURE 22: Mean m i g r a t i o n p a t t e r n of experimental f r y ; S e c t i o n B, Experiment 2. ....................... 50 FIGURE 23: M i g r a t i o n p a t t e r n s c f experimental f r y w i t h i n a r t i f i c i a l stream channels. P l c t c f 'time p e r i o d s x f r y type' i n t e r a c t i o n , Appendix X. ... 50 FIGURE 24: M i g r a t i o n p a t t e r n s of experimental f r y w i t h i n a r t i f i c i a l stream channels. P l o t of 'time p e r i o d s x pr e d a t o r s ' i n t e r a c t i o n , Appendix X. ... 50 FIGURE 25: M i g r a t i o n p a t t e r n s of (a) f a s t migrants, (t) slow migrants, and (c) experienced f r y i n a r t i f i c i a l stream channels with and without p r e d a t o r s . ..................................... 51 v i i i FIGOEE 26: FIGURE 27: FIGURE 28: FIGURE 29: FIGURE 30: FIGURE 31: FIGUEE 32: FIGUEE 33: FIGURE 34: FIGURE 35: FIGURE 36: FIGURE 37: Percent migrants w i t h i n the f i r s t , hour f o r experimental f r y , s u b j e c t e d to l i g h t treatments, m i g r a t i n g tnrough a r t i f i c i a l stream channels with and without predators. .................... 53 Percent migrants f o r experimental f r y , s u b j e c t e d to l i g h t treatments, m i g r a t i n g through a r t i f i c i a l stream channels with and without p r e d a t o r s . ..................................... 53 Percent non-migrants f o r experimental f r y , subjected to l i g h t treatments, m i g r a t i n g through a r t i f i c i a l stream channels with and without p r e d a t o r s . ..................................... 53 P l o t of SWIMMING TIME f o r f r y su b j e c t e d to l i g h t treatments. .................................... 62 P l o t of RESTING TIME f o r f r y s u b j e c t e d t c l i g h t treatments,. .................................... 62 P l o t of SCHOOL LENGTH f o r f r y subjected t c l i g h t treatments. .................................... 63 P l o t o f SCHOOL FORMATION f o r f r y subjected to l i g h t treatments. .............................. 63 Experimental tank; S e c t i o n C, Experiment 2. .... 66 Experimental tank c o n t a i n i n g f r y ; Secti o n C, Experiment 2. .................................. 66 Distance moved by one f i s h , i n a grcup of ten f r y , during a seven h o u r ' o b s e r v a t i o n p e r i o d . ... 68 Movement p a t t e r n s of dark-adapted f r y s u b j e c t e d to v a r i n g time p e r i o d s of l i g h t treatment. ..... .71 Summary of r e s u l t s f o r f r y subjected to v a r i o u s l i g h t treatments. 73 i x LIST OF TABLES TABLE I : Summary of r e s u l t s f o r migrants, non-migrants, eaten, and migrants i n the f i r s t 1.5 hour, i n an experiment t e s t i n g naive f r y migrating through a r t i f i c i a l stream channels with and without p r e d a t o r s . ..................................... 14 TABLE I I : Percent migrants i n the f i r s t hour f o l l o w i n g the onset of mig r a t i o n . Experiment t e s t e d f i v e f r y ty p e s , each from two sources, and a l l exposed to th r e e predator c o n d i t i o n s . ..................... 20 TAELE I I I : Percent migrants, non-migrants, and eaten, of v a r i o u s 'experienced 1 f r y , each frcm two sourc e s , and a l l subjected to three d i f f e r e n t p redator regimes. .............................. 21 TAELE IV: D e s c r i p t i o n of 'experienced' f r y were s u b j e c t e d to p r i o r t o examining migratory behavior. ...... 27 TAELE V: The percentage of 'experienced' f r y m i g r a t i n g through a r t i f i c i a l stream channels. ............ 27 TABLE VI: E x p e c t a t i o n s and r e s u l t s f o r experiment t e s t i n g f a s t migrants, slow migrants and experienced f r y i n a r t i f i c i a l stream channels with and- without p r e d a t o r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 TABLE VII: Summary of b e h a v i o r a l o b s e r v a t i o n s f o r f r y under simulated experimental c o n d i t i o n s . ............. 59 TAELE V I I I : Summary of a n a l y s i s f o r f r y observed f o l l o w i n g v a r i a b l e l i g h t treatments. ..................... 60 TABLE IX: E e s u l t s from a n a l y s i s of v a r i a n c e and Duncan's New M u l t i p l e Eange Test f o r : (a) mean movement per 30 min o b s e r v a t i o n p e r i o d , and (b) t i n e taken to s t a r t swimming f o l l o w i n g dark r e c u p e r a t i o n . .................................. 69 X LIST OF APPENDICES APPENDIX I: Three-way a n a l y s i s of va r i a n c e on a r c s i n e transformed values of percent migrants per sampling p e r i o d ; comparing d i f f e r e n c e s i n migration p a t t e r n s f o r naive f r y i n a r t i f i c i a l stream channels with and without pre d a t o r s , .................................. 96 APPENDIX I I : Four-way a n a l y s i s of varia n c e on a r c s i n e transformed values of percent migrants per sampling p e r i o d ; comparing d i f f e r e n c e s i n mig r a t i o n p a t t e r n f o r v a r i o u s experienced f r y , from two spawning channels, with and without p r e d a t o r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 APPENDIX I I I : Three-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants, non-migrants and eaten; comparing d i f f e r e n c e s i n these values f o r va r i o u s experienced f r y , from the two spawning ch a n n e l s , i n a r t i f i c i a l stream channels with and without p r e d a t o r s . . 98 APPENDIX IV: Two-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants per sampling p e r i o d ; comparing d i f f e r e n c e s i n migratio n p a t t e r n f o r v a r i o u s experienced f r y . ........... ...... 99 APPENDIX V: Three-way a n a l y s i s of v a r i a n c e cn a r c s i n e transformed values of percent migrants per sampling p e r i o d ; comparing migration p a t t e r n s of v a r i o u s f r y types m i g r a t i n g through a r t i f i c i a l stream channels with and without p r e d a t o r s . .......................... ........ 100 APFENDIX VI: Two-way a n a l y s i s of va r i a n c e on a r c s i n e transformed values of percent migrants per sampling p e r i o d ; examining e f f e c t c f predators on mi g r a t i o n p a t t e r n of the t h r e e f r y types. .................................. 101 APEENDIX V I I : Two-way a n a l y s i s of va r i a n c e on a r c s i n e transformed values o f percent migrants per sampling p e r i o d ; examining the response of each f r y type w i t h i n the v a r i o u s predatcr regimes. .................................... 102 x i APPENDIX V I I I : Two-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants i n the f i r s t hour f o l l o w i n g the onset of the experiment; comparing d i f f e r e n c e s i n these values f o r each f r y type i n a r t i f i c i a l stream channels with and without p r e d a t o r s . An a p o s t e r i o r i Duncan's New M u l t i p l e Eange Te s t compared d i f f e r e n c e s i n the means f o r each f a c t o r . «... 103 APPENDIX IX: Two-way a n a l y s i s of va r i a n c e on a r c s i n e transformed values of percent migrants, non-migrants and l o s t or eaten; comparing d i f f e r e n c e s i n these values f o r the f r y types i n a r t i f i c i a l stream channels with and without predators, . . ,.,,...................... .104 APPENDIX X: Four-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants per sampling p e r i o d ; comparing d i f f e r e n c e s i n migratio n p a t t e r n f o r the th r e e f r y t y p e s , subjected to th r e e l i g h t c o n d i t i o n s , i n a r t i f i c i a l stream channels with and without p r e d a t o r s . . .- ............. ................ ... 105 APPENDIX XI: Three-way a n a l y s i s of v a r i a n c e cn a r c s i n e transformed values of percent migrants i n the f i r s t hour, migrants and non-migrants; comparing d i f f e r e n c e s i n these values f o r the f r y t y p e s , s u b j e c t e d t o three l i g h t c o n d i t i o n s , m igrating through stream channels with and without p r e d a t o r s . ................. 106 APEENDIX X I I : C o l l e c t i o n , f e r t i l i z a t i o n and procedures f o r salmon roe and f r y l a b o r a t o r y s t u d i e s . ............. i n c u b a t i o n u t i l i z e d i n 107 ACKNOWLEDGEMENTS I would l i k e t o express my s i n c e r e g r a t i t u d e to Dr. P.A. . l a r k i n f o r h i s c h e e r f u l encouragement, s t i m u l a t i n g guidance and generous support throughout a l l phases o f t h i s study. Dr. W.S. Hoar, Dr. N.E. L i l e y and A.Y. Fedorenko c r i t i c a l l y reviewed and provi d e d h e l p f u l comments on t h i s t h e s i s . F i s h e r i e s and Marine S e r v i c e provided support and accommodation throughout the f i e l d work. I would l i k e to thank E. , G i n e t z , I . MacLean, and E. Dickson f o r t h e i r a s s i s t a n c e i n the f i e l d at F u l t o n E i v e r . A s p e c i a l thanks to Helen Hahn who provided advice and a s s i s t a n c e whenever needed. I would a l s o l i k e to thank c l o s e f r i e n d s and a s s o c i a t e s f o r p r o v i d i n g a s s i s t a n c e i n v a r i c u s ways. F i n a l l y , I e s p e c i a l l y thank my parents f o r t h e i r i n c r e d i t l e p a t i e n c e and mcral support throughout t h i s study. 1 INTRODUCTION I t has long been known t h a t predators i n f l i c t s u b s t a n t i a l m o r t a l i t y upon p o p u l a t i o n s of emergent salmcnid f r y (Neave 1953). In a., ten year study on m i g r a t i n g pink and chum f r y , Hunter (1959) estimated m o r t a l i t y due t o pre d a t i o n to range between 23 and 86 percent. Although t h e r e i s a l a r g e s p a t i a l and temporal v a r i a b i l i t y i n the degree of p r e d a t i o n , a l l salmonids migrating frcm spawning grounds i n t o a s s o c i a t e d r e a r i n g area w i l l be s u b j e c t e d t c t h i s pressure. Thus i t i s of i n t e r e s t t o determine and understand the components of f r y behavior t h a t a f f e c t predator-prey i n t e r a c t i o n s d u r i n g t h i s r e l a t i v e l y short phase of t h e i r l i f e c y c l e . The impetus f o r the f o l l o w i n g study was the o b s e r v a t i o n by Gin e t z (1972) and Ginetz S L a r k i n (1976) t h a t ' e x p e r i e n c e d 1 and 'enumerated' sockeye salmon f r y (Oncorhynchus nerka) had an in c r e a s e d s u r v i v a l r a t e and d i s p l a y e d migration p a t t e r n s d i f f e r e n t from those of in e x p e r i e n c e d f r y . These changes presumably r e s u l t e d frcm an experience of predation and p h y s i c a l d i s t u r b a n c e during enumeration. Newly emerged f r y ('inexperienced') have e v i d e n t l y had l i t t l e o p p o r t u n i t y t o a c g u i r e experiences and develop a p p r o p r i a t e behavior. Thus experiments were designed t o f u r t h e r examine var i o u s aspects o f b e h a v i o r a l development i n emergent f r y . I n i t i a l f i e l d experiments (Section A) sought: (1) to s u b s t a n t i a t e changes i n migratory behavior of emergent f r y f o l l o w i n g an experience with a predator, that i s , to see what a f r y l e a r n s from a predator or what i n f l u e n c e a pr e d a t c r has upon 2 a f r y t h a t i s not eaten; (2) t o see i f v a r i o u s experiences r e s u l t i n s i m i l a r behavior p a t t e r n s . The number c f d i f f e r e n t s p e c i e s of predators c o e x i s t i n g i n a stream can be c o n s i d e r a b l e , thus migratory behavior of i n e x p e r i e n c e d f r y s u b j e c t e d to d i f f e r e n t predators was examined t o d e t e c t any d i f f e r e n c e s i n p a t t e r n s of downstream movement; (3) to e v a l u a t e how the enumeration procedure a f f e c t s n a i v e , i n e x p e r i e n c e d f r y , producing a r e s u l t t h a t resembles an experienced f r y . The c l o s e p r c x i m i t y of two sources of naive f r y prompted a f u r t h e r experiment t c determine i f f r y , from a p o t e n t i a l l y d i s t i n c t spawning stock, and reared under d i f f e r e n t c o n d i t i o n s , respond d i f f e r e n t l y t c e x p e r i e n c e s . E e s u l t s from the f o r e g o i n g experiments, a re-examination of G i n e t z ' s (1972) work, and a p r e l i m i n a r y l a b o r a t o r y study provided a base f o r a second f i e l d season (Section B) to examine: (1) the b e h a v i o r a l c h a r a c t e r i s t i c s of emerging f r y and t h e i r response to predators; and (2) the e f f e c t of l i g h t on migratory behavior of f r y emerging from a dark environment. F i n a l l y , l a b o r a t o r y s t u d i e s (Section C) were designed to determine: (1) f r y response t o l i g h t f o l l o w i n g emergence, and (2) f a c t o r s i n v o l v e d i n the i n i t i a t i o n of s c h o o l i n g b e h a v i c r . Due to the d i v e r s i t y of s u b j e c t s i n v o l v e d , and f o r ease i n w r i t i n g , the experimental work has been presented i n c h r o n o l o g i c a l order. Only a b r i e f i n t r o d u c t i o n t o the experiments has been presented i n t h i s s e c t i o n . A comprehensive development of the work and a s s o c i a t e d l i t e r a t u r e survey i s presented i n the d i s c u s s i o n . 3 SECTION A: EFFECT OF PBEDATOHS AND EXPERIENCE ON MIGRATORY BEHAVIOR M a t e r i a l s and Methods F i e l d work was conducted at the Department of the Environment ( F i s h e r i e s and Marine Service) F u l t o n R i v e r spawning channels, at Babine Lake, B r i t i s h Columbia (Figure 1a&b). To mimic spawning channel c o n d i t i o n s and c o n t r o l experimental p o s s i b i l i t i e s , three i d e n t i c a l stream channels s i m i l a r to those cf G i netz (1972), were placed w i t h i n l e g 1 cf Spawning Channel No. 2 (Eigure 2aSb). Each trough (7.3 x 0.6 x 0.5 m), c o n s t r u c t e d o f 3/4 i n c h plywood, was d i v i d e d crosswise i n t o 2 s e c t i o n s : 6.1 u> as a predator-prey i n t e r a c t i o n area, with the upper 1 m f o r i n i t i a l temporary prey a c c l i m a t i z a t i o n ; the remaining 1.2 m a pr e y - t r a p p i n g area. The prey t r a p s (Figure 3) c o n s i s t e d of a s o c k - l i k e t r a p f i t t e d to a l a r g e r f y k e - t r a p c f dimensions 0.9 x 0.6 x 0.4 m. Metal window s c r e e n i n g (1 mm2 mesh s i z e ) covered the f r o n t and top of the troughs. The water depth w i t h i n the troughs remained at approximately 30 cm. The flow v e l o c i t y averaged 17 ± 2 cm/sec, was adjusted by a m c v a b l e - s l i t arrangement, and was checked d a i l y using a Teledyne Gurley meter. To compensate f o r water c u r r e n t v a r i a t i o n s w i t h i n the spawning channels, an extensive weir set-up was c o n s t r u c t e d at the upstream end. The experimental sockeye salmon f r y were c o l l e c t e d from FIGURE l a : G e o g r a p h i c l o c a t i o n o f B a b i n e Lake and F u l t o n R i v e r . FIGURE l b : F u l t o n R i v e r and a d j a c e n t spawning c h a n n e l s . FIGUEE 2a: A r t i f i c i a l stream c h a n n e l s ; l o c k i n g downstream. Each t r o u g h c o n s i s t e d c f twc s e c t i o n s : p r e d a t o r - p r e y i n t e r a c t i o n a r e a and p r e y - t r a p p i n c a r e a . Flow v e l o c i t y was a d j u s t e d hy m o v a t l e - s l i t arrangement at t h e upstream end. FIGUEE 2h: A r t i f i c i a l stream c h a n n e l s ; l o c k i n g upstream. E r e y - t r a p s are not i n o p e r a t i o n . 7 IIGDEE 3: Prey-rtrap a t downstream end of each t r c u g h . f r y were c o l l e c t e d i n t h e s o c k - ^ l i k e t r a p a t t a c h e d t o t h e l a r g e r f y k e - t r a p . 8 Spawning Channels No. 1 and 2. F o r the experimental p e r i o d , the mean len g t h s (mm) and mean weights (mg) f o r Channel No. 1 f r y were 29.83 mm and 157.93 mg r e s p e c t i v e l y ; and f o r Channel No. 2 f r y , 30.32 mm and 148,11 mg r e s p e c t i v e l y . For both channels, yelk a b s o r p t i o n was near complete f o r a l l e x p e r i m e n t a l f r y ; t h a t i s , stage 5 of development (Ginetz, 1972). For use i n the experiments, two b a s i c f r y types were c o l l e c t e d during peak downstream mi g r a t i o n hours (2230-0130 hours); these were def i n e d as INEXPERIENCED and ENOMERATED. Depending upon the experimental design, v a r i o u s ether types of f r y were reeded, and these w i l l be d e s c r i b e d i n the a p p r o p r i a t e s e c t i o n s . INEXPERIENCED f r y were assumed t o be n a i v e , t h a t i s , they were captured s h o r t l y f o l l o w i n g emergence from the g r a v e l , t h e r e f o r e having had l i m i t e d o p p o r t u n i t y to encounter an •experience*. For both channels the i n e x p e r i e n c e d f r y were c o l l e c t e d during n i g h t - t i m e m i g r a t i o n hours with d i p n e t s at the counting f e n c e s , t r a n s p o r t e d to the l a b i n buckets and s t o r e d i n darkened 10 g a l aquaria u n t i l the next evening. ENUMERATED f r y were c o l l e c t e d f o l l o w i n g the co u n t i n g procedure c a r r i e d out by the F i s h e r i e s s t a f f . For Channel Ko. 2, the f r y were captured i n converging t h r e a t t r a p s , washed i n t o and drained out of a 227 l i t r e f i b e r g l a s s tub i n t o a w a t e r f i l l e d 12 l i t r e p o l y e t h y l e n e bucket. The bucket was then t r a n s p o r t e d i n t o a nearby enumeration room where the f r y were hand counted and swept i n t o a trough which extended back i n t o the r i v e r . Curing the counting procedure f r y were subjected to r a p i d i n c r e a s e s i n l i g h t i n t e n s i t y (River: ca. 0.1 f t - c ; Enumeration 9 rocm: ca. 80 f t - c ) and p h y s i c a l h a n d l i n g . The enumeration procedure at Channel No. 1 v a r i e d by comparison with the o p e r a t i o n j u s t d e s c r i b e d , but the e s s e n t i a l f e a t u r e s of l i g h t i n t e n s i t y f l u c t u a t i o n s plus p h y s i c a l h a n d l i n g were the same. A Gossen Lunasix 3 exposure meter was used f o r a l l l i g h t i n t e n s i t y measurements. Eainbow t r o u t (Salmo .qairdneri) , of f o r k l e n g t h s i z e range 26-31 cm, and Mountain w h i t e f i s h (Prosopium w i l l i a m s o n i ) , of f o r k l e n g t h s i z e range 28-31 cm, were used as pr e d a t o r s . Both were caught by beach s e i n i n g and a n g l i n g i n F u l t o n P i v e r , j u s t downstream of the spawning channel e x i t . The f i s h were s t o r e d f o r three days i n a l i v e box t o confirm t h e i r h e a l t h ; then t r a n s f e r r e d to one of the a r t i f i c i a l stream channels at l e a s t 48 hours p r i o r t o an experiment. For predator i n t e r a c t i o n s t u d i e s , trough number 1 was v o i d of p r e d a t o r s , trough number 2 contained 6 rainbow t r o u t , and trcugh number 3 contained 6 w h i t e f i s h . Care was taken t o s t a n d a r d i z e the predator s i z e , and to remove any t h a t were developing fungus i n f e c t i o n s . Excessive a l g a l and sediment b u i l d - u p cn the screens and w i t h i n the troughs n e c e s s i t a t e d d a i l y c l e a r i n g i n the e a r l y evening, a f t e r which, v e l o c i t y was checked and a c l o s e i n s p e c t i o n made f o r any f r y t h a t might be present. Approximately 1 hour p r i o r t o an experiment, the number of f r y f o r a t r i a l was counted out from the h o l d i n g a q u a r i a i n t o a bucket, and t r a n s f e r r e d frcm the l a b to the f i e l d s i t e . As the i n c i d e n t l i g h t i n t e n s i t y reached 0.05 f t - c the p a r t i t i o n was l i f t e d , s e t t i n g the s t a r t i n g time f o r the experiment. For approximately 10 4 hours, the p r e y - t r a p p i n g nets were checked each 1/2 hour f o r the number of f r y which had' migrated down the stream channel; the f r y so c o l l e c t e d were termed MIGRANTS. Depending upcn the experiment, the f r y once counted were e i t h e r r e l e a s e d i n t o the n a t u r a l channel or returned t o the aquaria f o r f u t u r e use. At 0800 hours the f o l l o w i n g morning, f r y remaining i n the trough were counted (NON-MIGRANTS), and those unaccounted f o r were assumed t o have been EATEN. The data concerning numbers of f r y migrating downstream each h a l f - h o u r , were converted t o percentages of e i t h e r the t o t a l number mi g r a t i n g , or, t o t a l number completing m i g r a t i o n , then a r c s i n e transformed p r i o r t o s t a t i s t i c a l a n a l y s i s . There were two avenues of data i n t e r p r e t a t i o n : (1) the m i g r a t i o n p a t t e r n s ( i . e . the number of f r y migrating w i t h i n each time p e r i o d ) , and (2) the r e l a t i v e p r o p o r t i o n s of migrants, non-migrants and eaten. In both cases parametric a n a l y s i s o f var i a n c e was used where a p p r o p r i a t e , f o l l o w e d by an a p o s t e r i o r i  t e s t (Duncan's New M u l t i p l e Range T e s t ) . I f the variances were heterogeneous, the data were processed with a non-parametric a n a l y s i s of v a r i a n c e ( K r u s k a l - W a l l i s Test) . 11 i t J, - E f f e c t of D i f f e r e n t Predators on Naive Fry Methods And E e s u l t s An i n i t i a l experiment t e s t e d whether the behavior p a t t e r n of i n e x p e r i e n c e d f r y was d i f f e r e n t when predators were p r e s e n t ; and f u r t h e r , whether d i f f e r e n t types of predators had the same e f f e c t . For three n i g h t l y t r i a l s , 75 i n e x p e r i e n c e d f r y were i n t r o d u c e d i n t o each of the t h r e e troughs; twc with p r e d a t o r s , rainbow and w h i t e f i s h r e s p e c t i v e l y , and the t h i r d p r e d a t o r - f r e e . A n a l y s i s of v a r i a n c e on the transformed data concerning percent migrants per h a l f - h o u r time p e r i o d s (Appendix I) shewed only the time p e r i o d ( i . e . migration pattern) f a c t o r to be s i g n i f i c a n t , whereas the predator e f f e c t and the n i g h t s e f f e c t (sequence of three t r i a l s ) were not s i g n i f i c a n t . The time p e r i o d e f f e c t (Figure 4) was c h a r a c t e r i z e d by an e a r l y peak i n the migration r a t e , f o l l o w e d e i t h e r by a r a p i d cr g r a d u a l d e c l i n e . For 6 of the t o t a l 9 runs i n the experiment, more than 75% o f the f r y had migrated downstream w i t h i n the f i r s t 1.5 hours. The l a c k of s i g n i f i c a n c e o f the ' n i g h t s ' f a c t o r suggested t h a t any changes i n a b i o t i c and/or b i o t i c f a c t o r s over the p e r i o d of d u r a t i o n of the experiment were not a f f e c t i n g the r e s u l t s . From the design of the experiment i t i s apparent t h a t the e f f e c t of the predators on the t i m i n g of the migrati o n i s measured by the 'predator x time' i n t e r a c t i o n . T h i s i n t e r a c t i o n was s i g n i f i c a n t , and F i g u r e 4, p l o t t i n g the transformed percent mean migrati o n p a t t e r n s f o r the three n i g h t s , , shows what happened, when predators were present t h e r e was a migration peak 12 • • no p r e d a t o r s • • ra i n b o w t r o u t A A w h i t e f i s h 3 4 5 0.5 hr s a m p l i n g p e r i o d s FIGURE 4: M i g r a t i o n p a t t e r n s of i n e x p e r i e n c e d f r y w i t h i n e x p e r i m e n t a l stream c h a n n e l s . P l o t o f 'time p e r i o d s x p r e d a t o r s +/-' i n t e r a c t i o n from a n a l y s i s of v a r i a n c e , Appendix I . Curves c a l c u l a t e d from the t o t a l number o f f r y c o m p l e t i n g m i g r a t i o n . 0.5 h r s a m p l i n g p e r i o d s FIGURE 5: M i g r a t i o n p a t t e r n s o f i n e x p e r i e n c e d f r y w i t h i n e x p e r i m e n t a l stream c h a n n e l s . Curves c a l c u l a t e d from the t o t a l number o f f r y s t a r t i n g each e x p e r i m e n t . Shaded a r e a r e p r e s e n t s the d i f f e r e n c e i n p r e d a t i o n between ra i n b o w t r o u t and w h i t e f i s h . 13 w i t h i n the f i r s t hour a f t e r onset o f migration; i n the p r e d a t o r - f r e e trough t h e r e was a more uniform migration p a t t e r n over the whole of the n i g h t . A n a l y s i s of v a r i a n c e , f o l l o w e d by an a p o s t e r i o r i Duncan's New M u l t i p l e Range T e s t , cn the percent migrated w i t h i n the f i r s t 1.5 hours f u r t h e r p i n p o i n t e d the d i f f e r e n c e between predator and p r e d a t o r - f r e e troughs (Table I ) . The predator troughs were shown t o be s i m i l a r , both having a gr e a t e r percentage compared to the p r e d a t o r - f r e e trough i n the f i r s t 1.5 hours. Table I summarizes the number and percentages of migrants, ncn-migrants and eaten. T y p i c a l l y , t here were fewer f r y migrating w i t h i n the non-predator trough than i n those c o n t a i n i n g p r e d a t o r s . Due to the h e t e r o g e n e i t y of v a r i a n c e , ( l a r g e l y a t t r i b u t a b l e t o the p r e d a t o r - f r e e trough on t r i a l number 1), a parametric a n a l y s i s of v a r i a n c e to compare the three troughs could not be done. Although a non-parametric a n a l y s i s of variance ( K r u s k a l - W a l l i s Test) r e s u l t e d i n acceptance of the n u l l hypothesis t h a t the trough means f o r percent migrants were eq u a l , a Duncan's New M u l t i p l e Range Test found a s i g n i f i c a n t d i f f e r e n c e between the w h i t e f i s h trough and the ether two, (Table I ) . T h i s d i f f e r e n c e i s a r e f l e c t i o n of the d i f f e r i n g p r o p o r t i o n s of non-migrants and eaten i n each trough, though the t e s t i s a d o u b t f u l i n d i c a t o r i n the circumstances of heterogeneous v a r i a n c e s . Parametric a n a l y s i s of v a r i a n c e showed a s i g n i f i c a n t d i f f e r e n c e f o r the percent migrants hetween the trough with w h i t e f i s h and rainbow, 60.0% and 44.0 5? r e s p e c t i v e l y ; a d i f f e r e n c e r e l a t e d to the percent eaten per trough. P l o t t i n g the TflEIE I : Summary of r e s u l t s f o r migrants, n c n - a i g r a i t s , eaten, and migrants i n the f i r s t 1.5 hour, i n an experiment t e s t i n g n a i v e f r y rcigrating through a r t i f i c i a l stream channels with and without p r e d a t o r s . r T - * i — T — 1 | | NO PBEDATGBS | BAINBOW | WHITEFISH | | B e p l i c a t e s l 1 2 3 | 1 2 3 | 1 2 3 | \ — — I - — + + -i | #Migrants | 47 28 28 | 34 31 34 J 47 44 44 | | #Non-migs | 28 47 47 | 1 0 0 | 0 1 0 | | #Eaten | - - - I 40 44 41 | 28 30 31 | | «Migs i n | 29 11 12 | 26 25 33 | 38 34 40 | I 1.5hr | | | | h 4 — + ^ | M i g r a n t s | 62.7 37. 3 37.3 | 45,.3 41.3 45.3 | 62.7 58.7 58.7 | | SNcn-migs j 37.3 62. 7 62.7 | 1.3 0 0 | 0 1.3 0 J | SJEaten | - - | 53.3 58.7 54.7 | 37.3 40.0 41.3 | | SMigs i n | 38.7 14.7 16.0 | 34.7 33.3 44.0 | 50.7 45.3 53. 3 | I 1.5hr | | ! | | j. 1 + x 1 j . + I I I | Mean ^Migrant J 45.8 44.4 60.0 I J E. N.M.E.T. | I Mean ??Non-mig | 54. 2 0.4 0.4 E.N.M.B.T. I Mean EEaten | — 55.6 39.5 Mean ?(Mig i n | 23.1 37. 3 49.8 1.5hr I I.N.M.E.T. | L _ , I, , 1 D.N.M.E.T. = Duncan*s New M u l t i p l e Bange Te s t (Underscored means are not s i g n i f i c a n t l y d i f f e r e n t . ) 15 percent migrating f o r each time p e r i o d (Figure 5 ) , c l e a r l y shows the d i f f e r e n c e i n the migration p a t t e r n s between the two predator troughs. (This graph d i f f e r s frcm F i g u r e 4 which expresses the percentages of migrants t h a t migrated i n each time p e r i o d , whereas F i g u r e 5 deals with the t o t a l number c f f r y s t a r t i n g the experiment). The observed d i f f e r e n c e (shaded area cn graph) i s accounted f o r by the degree c f p r e d a t i o n , the rainbow t r o u t seemingly being more e f f i c i e n t than w h i t e f i s h , (55.6% and 39.5% eaten r e s p e c t i v e l y ) . D i s c u s s i o n The f i r s t experiment posed two simple questions: (1) do predators i n some way a f f e c t the downstream m i g r a t i o n o f newly-emerged, in e x p e r i e n c e d sockeye salmcn f r y ? , and (2) what i s the e f f e c t of d i f f e r e n t p redators on these f r y ? With predators absent from the troughs the mi g r a t i o n p a t t e r n was dome-shaped; when predators vere present the downstream movement was more abrupt with a peak e a r l y i n the migratio n p e r i o d . These r e s u l t s are s i m i l a r t o f i n d i n g s by Gin e t z (1972). He suggested t h a t predators may evoke an •awareness' i n the f r y which may i n f l u e n c e the r a t e of mi g r a t i o n and the compactness of s c h o o l i n g ; hence the peaked migrat i o n p a t t e r n . C l e a r l y the former i s a p o s s i b i l i t y , the predators may simply chase or 'spook' the f r y downstream at a r a p i d r a t e . The compactness c f s c h o o l i n g remains a somewhat dubious c o n j e c t u r e . T h i s s u b j e c t w i l l be d e a l t with i n a l a t e r s e c t i o n . As f o r the second g u e s t i o n , although the migrati o n p a t t e r n 16 of the f r y was s i m i l a r i n the presence of i c t h p r e d a t o r s , the percent eaten was s i g n i f i c a n t l y l a r g e r f o r rainhow t r o u t (55.6%) as compared to w h i t e f i s h (39.5%). B e h a v i o r a l o b s e r v a t i o n s of predator-prey i n t e r a c t i o n s w i t h i n the troughs are l a c k i n g , so i t i s i m p o s s i b l e to understand f u l l y the processes o c c u r r i n g . Experiment 2 - E f f e c t of D i f f e r e n t Predators on Experienced Fry Methods And E e s u l t s A second set of experiments was designed to answer the guestions : (1) do d i f f e r e n t types of experiences a f f e c t f r y behavior?, (2) are the f r y frcm the two spawning channels s i m i l a r i n t h e i r m igration p a t t e r n ? , and (3) are predator encounters an i n f l u e n c i n g f a c t o r i n f r y b e h a v i c r , and i f so, do the v a r i o u s types of experienced f r y respond s i m i l a r l y to d i f f e r e n t predator s p e c i e s ? In t e s t i n g these g u e s t i o n s , a 5 x 2 x 3 f a c t o r i a l experiment was designed; with the f a c t o r s as f o l l o w s : 5 f r y types (inexperienced, enumerated, shocked, experienced by p r e v i o u s exposure to rainbow t r o u t , and, experienced by p r e v i o u s exposure t o w h i t e f i s h ) ; each from 2 d i f f e r e n t spawning channels; a l l exposed to the 3 c o n d i t i o n s (no p r e d a t o r s , with rainbow t r o u t and with w h i t e f i s h ) . In g e n e r a l , the m a t e r i a l and methods were f o l l o w e d as p r e v i o u s l y o u t l i n e d . Besides i n e x p e r i e n c e d and enumerated f r y , t h r e e a d d i t i o n a l types c f f r y - e x p e r i e n c e s were e s t a b l i s h e d . One 17 type was SHOCKED; t h i s c o n s i s t e d of p l a c i n g a number c f f r y i n a 12 l i t r e p o l y e t h y l e n e bucket with p e r f o r a t e d s i d e s , and s p r a y i n g with water at a maximum f o r c e f o r 60 seconds. T h i s o p e r a t i o n was c a r r i e d out approximately 3 hours before the experimental p e r i o d , and any f r y t h a t were damaged or d i e d within t h a t time were removed. The other two types of f r y , EXPERIENCED TO PEEDATOES, were f r y which had p r e v i o u s l y migrated dc*n an experimental stream channel c o n t a i n i n g e i t h e r rainbow t r o u t or w h i t e f i s h . Since EXPERIENCED f r y were the s u c c e s s f u l downstream migrants i n the predator troughs, the l o s s frcm p r e d a t i o n reduced the numbers a v a i l a b l e f o r subseguent experiments, and i t was not p o s s i b l e t o maintain the same f r y d e n s i t i e s throughout, the numbers ranging from 60 t o 120 f r y per t r i a l . However, there were no obvious t r e n d s or e f f e c t s of v a r y i n g the numbers of f r y . For data a n a l y s i s , a l l values were expressed as the percentage f o r a time p e r i o d , of the t o t a l number of f r y s t a r t i n g downstream m i g r a t i o n . The a n a l y s i s of v a r i a n c e was preceded by an a r c s i n e t r a n s f o r m a t i o n . The p a t t e r n of m i g r a t i o n ; For those f r y t h a t reached the o u t l e t end of the experimental trough, a n a l y s i s of v a r i a n c e with the t h r e e f a c t o r s , plus time p e r i o d s as the f o u r t h v a r i a b l e , shewed both the time p e r i o d s and the 'time periods x f r y experience' i n t e r a c t i o n to be s i g n i f i c a n t , (Appendix I I ) . The former i m p l i e s only t h a t the number of f r y migrating was net the same i n a l l time p e r i o d s f o r a l l treatment groups. The i n t e r a c t i o n term i m p l i e s t h a t the d i f f e r e n c e s between time p e r i o d s was not the same f o r the various types of f r y , which 18 a p p a r e n t l y was a t t r i b u t a b l e t o the behavior of the w h i t e f i s h experienced f r y (Figure 6). The number of migrating w h i t e f i s h experienced f r y remained constant f o r the f i r s t 1.5 hours then g r a d u a l l y d e c l i n e d , whereas f o r the f o u r other f r y types, there was a sharp decre.ase i n numbers over the migration p e r i o d . T h i s d i f f e r e n c e i s emphasized i n Table I I , showing the percent migrants i n the f i r s t hour f o l l o w i n g the onset of m i g r a t i o n . In the t h r e e predator regimes, the w h i t e f i s h experienced f r y u s u a l l y had the fewest migrants. Although a n a l y s i s of v a r i a n c e accepted the n u l l h y p o t h e s i s , a Duncan's New M u l t i p l e Range Test shewed the w h i t e f i s h experienced f r y to be s i g n i f i c a n t l y d i f f e r e n t from the other t y p e s . To summarize, the main e f f e c t s , f r y e x p e r i e n c e , f r y o r i g i n s , and the presence or absence of predators had no s i g n i f i c a n t e f f e c t upon the n i g h t l y p a t t e r n of m i g r a t i o n f o r the f r y which reached the c u t l e t . The p a t t e r n of s u r v i v a l : Not a l l of the f r y accomplish m i g r a t i o n , a percentage are eaten. Table I I I presents the data f o r percent migrants, percent non-migrants and percent eaten, over the whole n i g h t l y m i g r a t i o n . A n a l y s i s of v a r i a n c e showed the predators to have a s i g n i f i c a n t e f f e c t w i t h i n each c f these three c a t e g o r i e s (Appendix I I I ) . The percent m i g r a t i n g was s i g n i f i c a n t l y g r e a t e r i n the w h i t e f i s h trough than that f o r no p r e d a t o r s , which was i n t u r n g r e a t e r than that i n the rainbow trough; the l a t t e r having y i e l d e d the s m a l l e s t percent migrants, (corresponding to the l a r g e number of f r y consumed by the t r o u t ) . Although the w h i t e f i s h trough had the g r e a t e s t percent c f migrants, the no predator trough had the g r e a t e s t percentage 19 50 0.5 hr s a m p l i n g p e r i o d s FIGURE 6: M i g r a t i o n p a t t e r n s of v a r i o u s ' e x p e r i e n c e d ' f r y w i t h i n e x p e r i m e n t a l stream c h a n n e l s . P l o t o f 'time p e r i o d s x e x p e r i e n c e ' i n t e r a c t i o n from a n a l y s i s o f v a r i a n c e , Appendix I I . Curves c a l c u l a t e d from the t o t a l number of f r y s t a r t i n g each e x p e r i m e n t . FIGURE 7: The e f f e c t o f p r e d a t o r p r e s e n c e / a b s e n c e on p e r c e n t m i g r a n t s f o r each spawning c h a n n e l . P l o t of ' p r e d a t o r s +/- x c h a n n e l s ' i n t e r a c t i o n from a n a l y s i s o f v a r i a n c e . Appendix I I . 20 TABLE I I : Percent migrants i n the f i r s t hcur f o l l o w i n g the onset of m i g r a t i o n . Experiment t e s t e d 5 f r y types (inexperienced, enumerated, shocked, experienced to rainbow, experienced t o w h i t e f i s h ) , each from 2 sources, and a l l exposed t o three c c n d i t i c n s (no pr e d a t o r s , with rainbow t r o u t , and with w h i t e f i s h ) . INEXPEE. r JO PREDATOR Channel 1 «• 2 BAINEOW Channel 1 " 2 WHITEE3SH Channel 1 " 2 80 68 54 50 68 73 ENUMEB, | SHOCKED | EAINBOW EXPEE. . 63 37 45 80 57 73 80 43 48 48 88 88 73 50 T ' — I WEITE. EXPEE. +— i 67 20 60 72 68 83 48 40 62 53 Mean Variance j. E,.N.M,R,.T. 65.50 130.24 59. 17 267.34 65. 83 468.23 67.67 130.66 48.33 285.91 D. N.M-E.T. = Duncan's New M u l t i p l e Range Test (Underscored means are not s i g n i f i c a n t l y d i f f e r e n t . ) 21 TAELE I I I : Percent migrants, non-migrants, and eaten of va r i o u s 'experienced' f r y , each from two sources, and a l l s u b j e c t e d t o three d i f f e r e n t predator regimes. (a) %MIGB ANTS I I I Channels I Inexperience d Enumerated Shocked Bainbow Exper. W h i t e f i s h Exper. NO PBEDATOB BAINBOW WHITEFISH — . — | — _ _ _ _ _ _ — _ _ _ _ _ 90.0 7 5. 0 j 57.8 £5.0 I 85. 0 80. 0 83.3 51.7 | 51.7 86.7 I 68. 3 86. 7 91.7 76.7 | 50.0 75.0 I 95. 0 96. 3 83. 3 83.3 | 65.0 80.0 I 86. 7 100. 0 91.7 5 5.0 | 68.3 63.3 I 81. 7 90. 0 MEAN 78. 17 68.28 87. 17 r H D. N.M.E.T. ** A l l S i g n i f i c a n t l y D i f f e r e n t ** (b) %NON-MIGEANTS Inexperienced I 10.0 16.7 | 3.9 2. 5 | 2. 5 0. 0 Enumerated I 8.3 16.7 I 5.0 0. 0 I 3. 3 3. 3 Shocked I 8.3 2 5.0 | 13.3 3. 3 I 1. 7 0,. 0 Eainbow Exper. I 48.3 23.3 | 0. 0 3. 3 | 0. 0 0. 0 Wh i t e f i s h Exper. | 16.7 -+ 45.0 | 5.0 1. 7 | L _ . 3. 3 1. 7 MEAN B.N.M.E.T. 21.83 3. 80 1.58 (C ) %EATEN Inexperienced | I 38.3 12 .5 | 12.5 20. 0 Enumerated | I 43.3 13 .3 | 28.3 10.0 Shocked | I 36.7 21 -7 | 3.3 1.7 Eainbow Exper. | 1 35.0 16 .7 | 13.3 0i 0 W h i t e f i s h Exper. | 1 26.7 35 • 0 | 15.0 £.3 MEAN | 27.92 11. 24 D.N.M.E.T. | S i g n i f i c a n t l y D i f f e r e n t CHANNEL MEANS | 36.00 19 .84 14.48 8.00 D.N.M.E.T. Chan.1 f r y s i g . d i f . from Chan.2 f r y D.N.M.E.T. = Duncan's New M u l t i p l e Bange Test (Underscored means are not s i g n i f i c a n t l y d i f f e r e n t . ) 22 of non-migrants. Channel No. 1 f r y were eaten at approximately twice the r a t e compared to Channel No. 2 f r y (Table I I I c ) , and the 'predators x channels' i n t e r a c t i o n f o r percent migrants was s i g n i f i c a n t . T h i s l a t t e r d i f f e r e n c e between the two spawning channels was not the same f o r the three predator systems (Figure 7 ) . For both predator channels, a h i g h e r value of percent migrants was found f o r Channel No. 2 f r y ; whereas the reverse was t r u e f o r the p r e d a t c r - f r e e trough. D i s c u s s i o n Ginetz (1972) found t h a t experienced and enumerated f r y d i s p l a y e d behavior p a t t e r n s which were d i f f e r e n t from in e x p e r i e n c e d f r y . Both experience and enumeration i n c r e a s e d s u r v i v a l r a t e , enhanced s c h o o l i n g t e n d e n c i e s , and a l t e r e d m igration p a t t e r n s (Ginetz, 1972; Ginetz & l a r k i n , 1S76). These r e s u l t s l e d to some s p e c u l a t i o n r e g a r d i n g the e f f e c t s of, v a r i o u s experiences on migratory behavior, and, the ways i n which experienced f r y r e a c t i n d i f f e r e n t predator regimes. I t was assumed a p r i o r i that a l l fo u r experiences would produce s i m i l a r e f f e c t s on the f r y , r e s u l t i n g i n p a t t e r n s d i s t i n c t frcm the i n e x p e r i e n c e d p a t t e r n , but t h i s f a i l e d to m a t e r i a l i z e . T h i s s et of experiments f a i l e d t o shew c l e a r c u t d i f f e r e n c e s i n n i g h t l y migration p a t t e r n among the var i o u s experienced f r y groups, a l l , except w h i t e f i s h - e x p e r i e n c e d f r y , d i s p l a y e d s i m i l a r migration p a t t e r n s . Assuming that the r e s u l t s were not due to the e f f e c t s being s m a l l and the v a r i a b i l i t y 23 being l a r g e , one concludes t h a t the i n e x p e r i e n c e d f r y are perhaps, experienced. I t was a l s o expected that (1) with no pre d a t o r s , i n e x p e r i e n c e d f r y would show l i t t l e m i g r a t i o n a c t i v i t y w i t h i n the f i r s t hour, ( i . e . movement more spread cut over the r i g h t ) , and, t h a t f o r the percent migrants i n the f i r s t hour the decreasing c r d e r would be: Bainbow experienced = W h i t e f i s h experienced > Enumerated > Shocked >> Inexperienced. (2) With predators the e x p e c t a t i o n s were t h a t the percent migrants i n the f i r s t hour would be greater f o r experienced f r y than f o r i n e x p e r i e n c e d f r y . F i n a l l y , i t was a n t i c i p a t e d t h a t (3) there wculd be more migrants i n the f i r s t hour i n the predator systems than i n the no-predator system. The r e s u l t s , summarized i n F i g u r e 8, f a i l t o agree with the f i r s t two e x p e c t a t i o n s and o n l y p a r t i a l l y c o n f i r m the t h i r d . Since these e x p e c t a t i o n s seemed v a l i d and c o n s i s t e n t with previous experiments (Ginetz, 1972), i t i s p o s s i b l e t h a t the migration p a t t e r n r e s u l t s i n t h i s experiment r e f l e c t e d t h a t a l l cf the f r y had some pr e v i o u s l e a r n i n g h i s t c r y t h a t made them a l l respond as experienced f r y . a n a l y s i s of the percent migrants, ncn-ffiigrants and eaten shewed s i m i l a r r e s u l t s as those i n preceding experiments; the predator e f f e c t was s i g n i f i c a n t . Two important phenomena were observed; f i r s t , the two p r e d a t o r s were not s i m i l a r i n t h e i r e f f e c t upon the f r y . Rainbow consumed s i g n i f i c a n t l y more f r y , hence t h e r e were fewer migrants. Secondly, the percent non-migrants i n t h e p r e d a t o r - f r e e trough was not s i g n i f i c a n t l y d i f f e r e n t from the percent eaten i n the rainbow trough. 24 100 90 80 70 cn 60 E 50 40 30 l e x . S.;R.E S. W.E. l e x . - i n e x p e r i e n c e d En. - enumerated S. - shocked R.E. - rainbow e x p e r i e n c e d .W.E. - w h i t e f i s h e x p e r i e n c e d no p r e d a t o r s rainbow w h i t e f i s h E x p e r i m e n t a l stream c h a n n e l s FIGURE 8: Summary o f r e s u l t s f o r p e r c e n t m i g r a n t s i n the f i r s t hour; showing response of v a r i o u s ' e x p e r i e n c e d ' f r y i n d i f f e r e n t p r e d a t o r r e g i m e s . 40 V • • i n e x p e r i e n c e d • -• enumerated o o tub w i t h no l i g h t s A A tub w i t h l i g h t s a A s t i r r e d 1 2 3 4 5 6 7 0.5 hr s a m p l i n g p e r i o d s FIGURE 9: M i g r a t i o n p a t t e r n s o f v a r i o u s ' e x p e r i e n c e d ' f r y w i t h i n e x p e r -i m e n t a l stream c h a n n e l s . P l o t o f 'time p e r i o d s x e x p e r i e n c e ' i n t e r a c t i o n from a n a l y s i s o f v a r i a n c e , Appendix IV. Curves c a l c u l a t e d from the t o t a l number of f r y s t a r t i n g each e x p e r i m e n t . 25 Although the two spawning channels are i n c l o s e p r o x i m i t y , the r e a r i n g c o n d i t i o n s are s l i g h t l y d i f f e r e n t and the spanning s t o c k s p o t e n t i a l l y d i f f e r e n t . The m i g r a t i o n p a t t e r n of the f r y from the two spawning channels was s i m i l a r , n e i t h e r experience nor predators had an e f f e c t . However, a n a l y s i s of the percent migrants and percent eaten showed two i n t e r e s t i n g r e s u l t s . For percent migrants, the i n t e r a c t i o n of 'channels x p r e d a t o r s ' was s i g n i f i c a n t ; i m p l y i n g t h a t w i t h i n a predator regime, percent migrants f o r each channel were d i f f e r e n t (Figure 7 ) . Secondly, twice the number of Channel No, 1 f r y was eaten compared to Channel No. 2 f r y (Table I I I c ) . G i netz (1972) found s i m i l a r r e s u l t s , Channel No. 1 f r y e x h i b i t i n g a g r e a t e r m o r t a l i t y . Both of these o b s e r v a t i o n s are p o s s i b l e i f the f r y from the two channels were d i f f e r e n t , yet the p h y s i c a l c h a r a c t e r i s t i c s f o r the f r y (page 8) of the two channels were extremely s i m i l a r . The f r y may be e x h i b i t i n g i n n a t e or a c q u i r e d b e h a v i o r a l t r a i t s which are a r e s u l t of d i f f e r e n t spawning stocks and/or d i f f e r e n t channel c o n d i t i o n s , o r , t h i s may j u s t be an a r t i f a c t of the experiment, r e s u l t i n g frcm s l i g h t l y d i f f e r e n t c o l l e c t i o n and t r a n s p o r t i n g methods. A d d i t i o n a l t e s t s may d i s c l o s e b e h a v i o r a l d i f f e r e n c e s which might produce t h i s v a r i a t i o n i n s u r v i v a l . 26 Experiment 2 ~ Comparison of Experienced and Enumerated | r j Methods And R e s u l t s A f i n a l f i e l d t e s t examined a p o i n t r a i s e d hy Ginetz (1S72), t h a t enumerated f r y have a g r e a t e r s u r v i v a l r a t e than non-enumerated f r y ; these two f r y types r e s p e c t i v e l y r e s e n b l i n g experienced and i n e x p e r i e n c e d f r y i n b e h a v i o r a l o b s e r v a t i o n s i n a g u a r i a . Since the supply of experimental f r y was l i m i t e d as the n a t u r a l f r y migration was nearing an end, the attempt to examine t h i s question was only a short-term i n v e s t i g a t i o n . The approach taken was to d i v i d e the enumeration procedure i n t o d i s t i n c t processes which i n themselves might have some e f f e c t upon the f r y , p o s s i b l y a l t e r i n g t h e i r behavior p a t t e r n s . Three separate d i v i s i o n s of the enumeration procedure (EXPERIENCES) were chosen (Table I V ) , and each was t e s t e d twice with 75 f r y , a n a l y z i n g migr a t i o n p a t t e r n , percent migrants and percent ncn-migrants. A two-factor a n a l y s i s of v a r i a n c e , number m i g r a t i n g per time p e r i o d and type of experience, showed the time periods and i n t e r a c t i o n t o be s i g n i f i c a n t (Appendix I V ) . The m i g r a t i o n p a t t e r n s were s i m i l a r t o those d e s c r i b e d i n p r e v i o u s experiments, d i s p l a y i n g a r a p i d i n c r e a s e i n numbers to a peak, f o l l o w e d by a gradual d e c l i n e i n the number m i g r a t i n g . The i n t e r a c t i o n term showed t h a t the m i g r a t i o n p a t t e r n s were d i f f e r e n t f o r the v a r i o u s types of experience (Figure 9). I t i s i n t e r e s t i n g t o note t h a t the 'tub with l i g h t s ' cur\e was d i s t i n c t l y d i f f e r e n t from the remaining f o u r curves; the f r y migrating downstream over a more concentrated time p e r i o d . 27 TABLE IV: D e s c r i p t i o n of 'experiences' f r y were subjected to p r i o r to e x a i n i n g migratory behavior. EXPERIENCE DESCRIPTION 1. Inexperienced As p r e v i o u s l y d e s c r i b e d within t e x t . 2. Enumerated I As p r e v i o u s l y d e s c r i b e d within t e x t . 3. Tut with NO LIGHTS Caught i n converging t h r o a t trap and emptied i n t o c o l l e c t i n g tub, fcithcut f l o o d l i g h t s cn. 4. Tub with LIGHTS | C o l l e c t e d as 3 above, but with l i g h t s on. These f r y d i f f e r from enumerated f r y i n t h a t they were not p h y s i c a l l y handled as d u r i n g the normal enumeration procedure. 5. S t i r r e d C o l l e c t e d s i m i l a r t c i n e x p e r i e n c e d f r y , placed i n a bucket and su b j e c t e d to c o n t i n u a l s t i r r i n g f o r approximately 2 minutes. This simulated c o n d i t i o n s f r y may encounter i n the converging t h r e a t t r a p . TAELE V: The percentage of 'experienced' f r y mi g r a t i n g through a r t i f i c i a l stream channels. Experiences as d e s c r i b e d i n Table IV. JfMigrant Mean Variance Inexper. 44.6 46. 9 45.75 2.65 Hand i n tucket 45. 4 46.2 45.80 0.32 Tub with NO LIGHT 62. 5 38.5 50.50 287.99 T T Enumer. | Tut with LIGHT 54. 8 49. 2 52.00 15. 68 75.0 53. 1 64.05 239.87 | -f | £.N.M.E.T. | D.N.M.R.T. = Duncan's New M u l t i p l e Range Test (Underscored means are not s i g n i f i c a n t l y d i f f e r e n t . ) 28 A s i m i l a r parametric a n a l y s i s on the percent migrants and percent non-migrants vas s t a t i s t i c a l l y i n v a l i d due to the he t e r o g e n e i t y c f the v a r i a n c e s a s s o c i a t e d with the experience means (Table V). Although a f u r t h e r non-parametric a n a l y s i s of varian c e ( K r u s k a l - W a l l i s t e s t ) found the mean values to be n o n - s i g n i f i c a n t , an a p o s t e r i o r i t e s t , Duncan*s New M u l t i p l e Bange Te s t , showed the 'tub with l i g h t s ' experience s i g n i f i c a n t l y d i f f e r e n t from the three experiences i n d i c a t e d on Table V, but s i m i l a r t o t h a t of the enumerated f r y . D i s c u s s i o n Ginetz (1972) found t h a t the enumeration procedure i n someway a l t e r e d the naive behavior p a t t e r n s of newly emerged f r y ; the r e s u l t a n t f r y most c l o s e l y resembled those encountering an experience. The quest i o n thence a r o s e , how does enumeration have an e f f e c t upon the f r y , and i n p a r t i c u l a r at what stage, or what component of the procedure, has the most s i g n i f i c a n t e f f e c t ? Enumeration and an 'experience' both enhanced f r y s c h c c l i n g t e n d e n c i e s noted i n aquarium o b s e r v a t i o n s , and i n c r e a s e d s u r v i v a l i n n i g h t l y trough experiments (Ginetz, 1972). I f one component of the enumeration procedure proved to be important i n i changing f r y behavior, p o s s i b l e r e l a t i o n s h i p s between s c h o o l i n g - s u r v i v a l and enumeration-experience could be p o s t u l a t e d . Although the experiment was only a b r i e f i n v e s t i g a t i o n and f a i l e d to show anything c o n c l u s i v e , i t d i d r e s u l t i n an 29 i n t e r e s t i n g p o i n t . The only component which had some e f f e c t upon the f r y was 'tub with l i g h t s ' . Since s i m i l a r f r y c o l l e c t e d i n the tub without l i g h t s d i s p l a y e d no d i f f e r e n c e i n migratory behavior compared to the other f r y 'types', i t i s p o s s i b l e t h a t the l i g h t s are a s i g n i f i c a n t f a c t o r . So a new g u e s t i c n i s phrased: does l i g h t , e i t h e r a r t i f i c i a l or n a t u r a l , i n f l u e n c e the behavior of i n e x p e r i e n c e d f r y ? 30 SECTION B : EFFECT OI PBEBATOBS AND LIGHT ON EMEBGING FEY M a t e r i a l and Methods The f i e l d s i t e was as noted i n the f o r e g o i n g s e c t i o n . Six troughs (Figure 10) were c o n s t r u c t e d s i m i l a r t c these p r e v i o u s l y d e s c r i b e d , with m o d i f i c a t i o n s added to the p r e y - t r a p p i n g area. I t was questioned whether the o r i g i n a l p r e y - t r a p p i n g design hindered the movement of t h e f r y i n t o the c o l l e c t i n g socks. To improve upon the method, open baskets with s l i d i n g f r o n t panels (Figure 11a&b) were used, reducing the p r e y - t r a p p i n g area to approximately 0.33 m. At each h a l f hour sampling p e r i o d a l l baskets were removed and f i s h counted (Figure 12) . The water depth was maintained at 30 ± 2 cm and the flew v e l o c i t y at 14 ± 2 cm/sec. Newly emerged sockeye f r y , termed NAIVE f r y , (average l e n g t h : 30.05 mm; average weight: 153.40 mg), were c o l l e c t e d during migration hours with the use of an i n c l i n e d - p l a n e t r a p s i t u a t e d i n l e g 13 of Spawning Channel No. 2 (Figure 13). The t r a p was o p e r a t i o n a l between 0030-0130 hours each evening. Captured f r y were c o l l e c t e d with d i p - n e t s , t r a n s p o r t e d to the l a r , and s t o r e d i n darkened 10 g a l a q u a r i a . Three types of experimental f r y were u t i l i z e d : (1) FAST MIGEANTS - naive f r y which had migrated - downstream over the n i g h t l y migration p e r i o d ; (2) SLOW MIGEANTS - naive f r y which d i d not migrate downstream during the n i g h t ; and (3) EXPEBIENCED f a s t migrant f r y which migrated down a predator channel. 3 1 IIGDEI 10: A r t i f i c i a l stream c h a n n e l s d u r i n g second f i e l d s e a son. Channels were s i m i l a r t o th o s e p r e v i o u s l y d e s c r i b e d , e x c e p t f o r p r e y - t r a p s l o c a t e d a t downstream end of t r o u g h s , l i v e - b o x e s f o r p r e d a t o r s are shewn a t f a r r i g h t o f photo. 32 FIGUEE 11a: Prey-trap. Wire screen prevented predators leaving t i e stream channels. FIGUEE 111: Prey-trap in position. Wood panel, at ri g h t of trap, was used to hold fry in the baskets and channels while sampling at each half hour i n t e r v a l . 33 FIGUEE 1 3 : I n c l i n e d - p l a n e t r a p used f o r c o l l e c t i n g emergent f r y . 34 O c c a s i o n a l l y a second type of experienced f r y was used, termed CHANNEL EXPERIENCED. These f r y were c o l l e c t e d from l a r g e s c h o o l s at the o u t l e t of Channel No. 2, having emerged frcm the g r a v e l at l e a s t 1-2 days p r i o r to c a p t u r e . Experimental predators (Rainbow t r o u t , f o r k l e n g t h s i z e range of 24-30 cm; and Mountain w h i t e f i s h , f o r k length s i z e range of 25-31 cm) were sei n e d a t the o u t l e t of Spawning Channel No. 2, and p r i o r t o experiments, s t o r e d i n l a r g e e n c l o s u r e s adjacent to the troughs. Predators were a c c l i m a t i z e d 48 hours i n the troughs. Predator s i z e was s t a n d a r d i z e d w i t h i n and between the troughs, and any f i s h developing fungus i n f e c t i o n s were replaced,. For undetermined reasons, high predator m o r t a l i t y was s u f f e r e d , e s p e c i a l l y i n rainbow t r o u t . T y p i c a l l y the snout and d o r s a l f i n d i s p l a y e d the f i r s t s i g n c f i n f e c t i o n ; p o s s i b l y r e s u l t i n g from contact with the i n s i d e of the troughs. The experimental procedure was s i m i l a r to that d e s c r i b e d i n the f o r e g o i n g s e c t i o n . Data c o n s i s t e d cf numbers of f r y migrating per h a l f hour sampling p e r i o d s , frcm which were c a l c u l a t e d the percent migrants, percent non-migrants, and percent l o s t or eaten. A n a l y s i s of the l a t t e r , percent l e s t or eaten, was not v a l i d as a t e s t of p r e d a t i o n ; problems with fungus i n f e c t i o n s tended t o reduce normal predator f e e d i n g behavior. A n a l y s i s of v a r i a n c e , f o l l o w e d by an a p o s t e r i o r i Duncan's New M u l t i p l e Range T e s t , was used on a l l data. A l l ccunts were c o r r e c t e d to percent of t o t a l s t a r t i n g , then a r c s i n e transformed. For most experimental runs the number of f r y per t r i a l was he l d at 60, although at times the number was v a r i e d due to l a c k of a v a i l a b i l i t y of c e r t a i n t y p e s , the numbers 35 ranging from 45 to 150 f r y . However, o b s e r v a t i o n c f the data shewed no c o r r e l a t i o n between i n c r e a s i n g the numbers and any of the measured r e s u l t s . Experiment J - E f f e c t of D i f f e r e n t Predators cn Emerging Fr y Methods find E e s u l t s To t e s t i f FAST, SLOW and EXPERIENCED f r y are d i f f e r e n t i n t h e i r migratory behavior, p l u s response to v a r i o u s p r e d a t o r s , a 3 x 4 f a c t o r i a l experiment, with 3 r e p l i c a t i o n s , was designed as f o l l o w s : three f r y types ( f a s t migrants, slow migrants, and experienced f r y ) t e s t e d i n each of f o u r predator regimes (6 rainbow t r o u t , 6 w h i t e f i s h , 3 rainbow/3 w h i t e f i s h , and no p r e d a t o r s ) . A n a l y s i s of v a r i a n c e on the transformed migration p a t t e r n data (Appendix V) showed a s i g n i f i c a n t d i f f e r e n c e i n the percent of. f r y migrating per sampling p e r i o d ; the number of f r y migrating decreased over the migrati o n p e r i o d (Figure 14). For comparison, the m i g r a t i o n p a t t e r n of naive f r y i s a l s o p l o t t e d on the same graph; fewer naive f r y migrated e a r l y i n the evening. S i g n i f i c a n c e was a l s o found f o r : (1) "time p e r i o d s x f r y type' i n t e r a c t i o n (Figure 15), the slow migrants p a t t e r n d i f f e r i n g from t h a t cf other f r y t y p e s , e s p e c i a l l y , fewer migrating i n the e a r l y evening, with a , g r e a t e r percent not migrating; and (2) 'time p e r i o d s x pr e d a t o r s ' i n t e r a c t i o n , (Figure 16), the average p a t t e r n f o r the pre d at or--free trough 1 2 3 4 5 6 N.M. 0.5 hr sampling periods FIGURE 14: Mean m i g r a t i o n p a t t e r n f o r e x p e r i m e n t a l and n a i v e f r y w i t h i n a r t i f i c i a l s t r e a m c h a n n e l s . P l o t o f 'time p e r i o d s ' f a c t o r from a n a l y s i s o f v a r i a n c e , Appendix V. 1 2 3 4 5 6 N.M. 0 . S hr sampling p e r i o d s FIGURE 15: M i g r a t i o n p a t t e r n s of e x p e r i m e n t a l f r y w i t h i n a r t i f i c i a l s t r e a m c h a n n e l s . P l o t o f 'time p e r i o d s x f r y t y p e ' i n t e r a c t i o n from a n a l y s i s o f v a r i a n c e , Appendix V. 37 d i f f e r e d from t h a t of the three predator channels, again fewer migrating throughout the n i g h t , and c o r r e s p o n d i n g l y , a l a r g e number of non-migrants. A d e t a i l e d examination of the experimental f a c t o r s shows the reasons f o r the f o r e g o i n g r e s u l t s . Appendices VI and VII summarizes the a n a l y s i s of v a r i a n c e f o r each of the f r y and predator types. In a l l cases the m i g r a t i o n pat t e r n e f f e c t was s i g n i f i c a n t , the number of migrants r a p i d l y d e c l i n e d over the m i g r a t i o n p e r i o d . With r e s p e c t t o f r y t y p e , the s i g n i f i c a n t i n t e r a c t i o n noted i n the o v e r a l l a n a l y s i s (Appendix V) i s c l e a r from the graphs i n F i g u r e 17a-c. The f a s t migrants and experienced f r y d i s p l a y the same g e n e r a l i z e d p a t t e r n of a r a p i d decrease i n numbers, yet the slew migrants d i s p l a y a gradual m i g r a t i o n p a t t e r n , with a g r e a t e r number c f f r y not m i g r a t i n g . Only the experienced f r y tended to behave d i f f e r e n t l y w i t h i n the channels, as noted i n Appendix VI ( s i g n i f i c a n t i n t e r a c t i o n term) and F i g u r e 17c; the experienced f r y p a t t e r n i n the p r e d a t o r - f r e e trough d e p a r t i n g s i g n i f i c a n t l y from the remaining t h r e e . The f a s t migrants d i s p l a y e d almost i d e n t i c a l p a t t e r n s i n the f o u r p r e e a t o r regimes; whereas the slow migrants were more e r r a t i c i n t h e i r r e a c t i o n t o the v a r i o u s predator types. Expressing the a n a l y s i s of the data i n terms c f the predator types shows how each of the f r y types r e a c t i n the d i f f e r e n t predator systems. Except f o r the rainbow t r o u t trough, the percentage of f r y migrating downstream per sampling p e r i o d was s i g n i f i c a n t l y d i f f e r e n t f o r each of the f r y types (Appendix VII - s i g n i f i c a n t i n t e r a c t i o n term). In the t h r e e p r e d a t o r (a) FAST MIGRANTS 0 . 5 h r s a m p l i n g p e r i o d s (C) EXPERIENCED 0.5 hr samp1ing p e r i o d s M i g r a t i o n patterns of (a) FAST MIGRANT, (b) SLOW MIGRANT, and (c) EXPERIENCED f r y wit h i n a r t i f i c i a l stream channels P l o t of 'time periods x predators' i n t e r a c t i o n from a n a l y s i s of variance, Appendix V l a - c . 39 systems (Figures 18a-c), the experienced and f a s t migrant f r y were sim i l a r , whereas the slow migrants had fewer migrants within the early evening and a greater percentage of non-migrants. In the absence of predators (Figure 18d), the migration patterns of the three f r y types were s i m i l a r , and resembled the migration of the naive f r y . In the two cases examined, the migration pattern of the channel experienced fry was similar to that of the f a s t migrants and experienced f r y . Since the major difference observed i n the migration patterns occurred within the f i r s t hour of the experiment, analysis of the percent migrants i n t h i s period further substantiated the migration pattern r e s u l t s . Analysis of variance (Appendix VIII) disclosed a s i g n i f i c a n t difference for both the f r y and predator type. A subseguent Duncan's New Multiple Bange Test showed the slow migrants tc be s i g n i f i c a n t l y different compared to the fast migrant and experienced f r y ; and the migrants within the predator-free trough to be s i g n i f i c a n t l y d i f f e r e n t to those in the three predator troughs. Separate analysis of the fry types and predator troughs for the percent migrants within the f i r s t hour (Figures 19 and 20), again showed the slow migrants, and f r y migrating down the predator-free trough to be different compared to the remainder. Greater than 70% of the experienced and fast migrant fry in the predator troughs migrated downstream within the f i r s t hour; whereas the percent slow migrants in a l l troughs, and percent fast migrants-experienced fry in predator-free troughs ranged between 40-70%. Analysis of the percentage migrants, non-migrants and l o s t ( a ) RAINBOW TROUT (b) WHITEFISH 7 0 I 7 0 I » 1 2 3 4 5 6 N.M. 1 2 3 4 5 6 N.M. 0 . 5 h r s a m p l i n g p e r i o d s 0 . 5 h r s a m p l i n g p e r i o d s FIGURE 18: Mi g r a t i o n patterns of experimental f r y within a r t i f i c i a l stream channels containing (a) RAINBOW TROUT, (b) WHITEFISH (c) RAINBOW/ WHITEFISH combination, and (d) NO PREDATORS. P l o t of 'time periods x f r y type' i n t e r a c t i o n from a n a l y s i s of variance, Appendix V l l a - d . o 41 (a) FAST MIGRANTS (b)SLOW MIGRANTS 100 _ 6 0 E 40 N.S . W R/W No p r e d a t o r s N.S. N.S. R/W No (c) EXPERIENCED 100 80 60 R Rainbow W W h i t e f i s h R/W R a i n b o w / W h i t e f i s h No No p r e d a t o r s 40 ** REJECT Ho ** N.S. , R W R/W No FIGURE 19: Means and c o n f i d e n c e l i m i t s o f ' p e r c e n t m i g r a n t s i n t h e f i r s t h o u r ' p l o t t e d f o r (a) FAST MIGRANT, (b) SLOW MIGRANT, and (c) EXPERIENCED f r y m i g r a t i n g w i t h i n e a c h o f f o u r p r e d a t o r r e g i m e s . A n a l y s i s o f v a r i a n c e f o u n d o n l y t h e e x p e r i e n c e d f r y means t o be s i g n i f i c a n t l y d i f f e r e n t . Duncan's New M u l t i p l e Range T e s t r e s u l t s a r e a l s o shown on g r a p h s ; means u n d e r s c o r e d by s o l i d l i n e a r e n o t s i g n i f -i c a n t l y d i f f e r e n t . 42 (a) RAINBOW (b) WHITEFISH s 1 0 0 8 0 6 0 4 0 1 0 0 8 0 6 0 4 0 N.S. N.S. F.M. S.M. Ex. f r y t y p e F.M. S.M. Ex. Ch. Ex. (c) RAINBOW/WHITEFISH (d) NO PREDATORS 1 0 0 8 0 6 0 4 0 1 0 0 i 6 0 4 0 ** REJECT Ho ** N.S. F.M. S.M. Ex. F.M. S.M. Ex. Ch. Ex. N. FIGURE 20: F.M. F a s t M i g r a n t s S.M. Slow M i g r a n t s Ex. E x p e r i e n c e d Ch.Ex. Chann e l E x p e r i e n c e d N. N a i v e Means and c o n f i d e n c e l i m i t s o f ' p e r c e n t m i g r a n t s i n t h e f i r s t h o u r ' p l o t t e d f o r t h e e x p e r i m e n t a l f r y m i g r a t i n g w i t h i n a r t i f i c i a l s t r e a m c h a n n e l s c o n t a i n i n g (a) RAINBOW TROUT, (b) WHITEFISH, (c) RAINBOW/WHITEFISH c o m b i n a t i o n , and (d) NO PREDATORS. A n a l y s i s o f v a r i a n c e f o u n d o n l y t h e means f o r t h e f r y t y p e s w i t h i n t h e r a i n b o w / w h i t e f i s h c h a n n e l t o be s i g n i f i c a n t l y d i f f e r e n t . Duncan's New M u l t i p l e Range T e s t r e s u l t s a r e a l s o shown on g r a p h s ; means u n d e r s c o r e d by s o l i d l i n e s a r e n o t s i g n i f i c a n t l y d i f f e r e n t . 43 or eaten, summarized i n Appendix IX, shewed both percent migrants and percent non^migrants s i g n i f i c a n t l y d i f f e r e n t f o r f r y and predator t y p e s ; while o n l y predator type was s i g n i f i c a n t f o r percent l o s t or eaten. Duncan's New M u l t i p l e Eange Test (Figure 21) found: (1) slow migrants s i g n i f i c a n t l y d i f f e r e n t , with fewer percent migrants and a corresponding g r e a t e r percent non-migrants; (2) the p r e d a t o r - f r e e trough s i g n i f i c a n t l y d i f f e r e n t compared to the other predator troughs, again with fewer percent migrants and a g r e a t e r percent non-migrants; and (3) the percent l o s t or eaten l a r g e s t f o r the w h i t e f i s h trough. Summarizing, a n a l y s i s of both migration p a t t e r n s and percent migrants, percent non-migrants and percent eaten agreed cn the f o l l o w i n g : (1) slow migrants responded d i f f e r e n t l y t o predators than f a s t migrants and experienced f r y ; the slow migrants d i s p l a y e d a more gradual m i g r a t i o n p a t t e r n with fewer f r y m i grating and c o r r e s p o n d i n g l y more non-migrants; and (2) predators i n f l u e n c e d the f r y m i g r a t i o n p a t t e r n f o r a l l f r y groups and the r e s u l t a n t r a t i o of migrants to non-migrants; noted as an i n c r e a s e d percentage of f r y n i g r a t i n g downstream both w i t h i n the f i r s t 1.5 hours and t o t a l l y over the evening. l i s c u s s i o n The f o r e g o i n g experiment was designed to examine two g u e s t i o n s : (1) Are naive f r y d i v i d e d i n t o f a s t and slow migrants, which d i s p l a y d i f f e r e n t migration p a t t e r n s and response t o v a r i o u s predators?; and (2) How does experience a l t e r behavior? 44 (a) % MIGRANTS C ni u oo 1 Fry Type F.M. S.M. E x . N a i v e Predators +/-R. W. R/W N o (b) % NON-MIGRANTS Fry Type C o c • V F.M. S.M. E x . N a i v e Predators +/-+ R. W. R/W N o (c) % LOST or EATEN loo, F r y Typ e 2 6 0 o Predators +/-+ F . M . S.M. E x . N a i v e R. W. R/W N o FIGURE 21: Means and c o n f i d e n c e l i m i t s o f p e r c e n t (a) MIGRANTS, (b) NON-MIGRANTS, and (c) LOST o r EATEN f o r t h e e x p e r i m e n t a l f r y m i g r a t i n g t h r o u g h a r t i f i c a l s t r e a m c h a n n e l s w i t h and w i t h o u t p r e d a t o r s . P l o t o f ' f r y t y p e ' and ' p r e d a t o r ' f a c t o r s f r o m a n a l y s i s o f v a r i a n c e , A p p e n d i x I X a - c . Duncan's New M u l t i p l e Range T e s t r e s u l t s a r e shown below e a c h g r a p h ; means u n d e r s c o r e d by s o l i d l i n e s a r e n o t s i g n i f i c a n t l y d i f f e r e n t . N a i v e f r y were n o t i n c l u d e d i n t h e a n a l y s i s . 45 I n i t i a l expectations and results are summarized i n Table VI. E r i e f l y , i t was expected that both experienced and fast migrant fry would display a s i g n i f i c a n t difference in migration pattern and percent migrants/non-migrants r a t i o , compared to slow migrant f r y . Experience was expected to increase any migration rates displayed by the fast migrant f r y ; and f i n a l l y , predators were expected to influence the measured parameters. As noted (Table VI), the comparison of fas t and slow migrants produced expected r e s u l t s . However, experienced f r y were not as d e f i n i t e i n showing the expected trends; although i n general behaving s i m i l a r l y to the fast migrants. This res u l t c o n f l i c t s with the foregoing experiments, regarding increased migration pattern and number of migrants f o r experienced f r y , compared to f a s t migrants, possibly indicating cne cf three things: (1) experimental v a r i a b i l i t y ; (2) the 'experience 1 i n t h i s set of experiments needed be reinforced to a greater degree; or (3) since the previous experiments f a i l e d to discriminate between fast and slow migrants, experience may have affected only fast migrants. The re s u l t s c l e a r l y indicate that sockeye f r y vary i n th e i r behavior with some describable as fast migrants and others as slew migrants. Both migration patterns and the r a t i o of percent migrants to percent non-migrants displayed a s i g n i f i c a n t difference between the fast and slow migrants. These fry may be two guite d i s t i n c t types, or there may be a l l degrees of intergrades between the two, the difference between ind i v i d u a l s r e f l e c t i n g a difference in environmental experience as well as inherited differences i n responsiveness to environmental 46 TABLE VI: Expectations and r e s u l t s f o r experiment t e s t i n g FAST MIGRANTS, SLOW MIGRANTS, and EXPERIENCED f r y i n a r t i f i c i a l stream channels with and without predators. PREDATOR TROUGHS NO PREDATOR TROUGH MIGRATION PATTERNS Fast Migrants (FM) -migrate r a p i d l y downstream ++ -slower migration compared to predator troughs, yet f a s t e r compared to SM i n no predator trough ++ Slow Migrants (SM) -slower migration compared to FM ( i e . fewer migrants w i t h i n the f i r s t hour) ++ -slower migration compared to FM, and p o s s i b l y slower com-pared to SM i n predator troughs ++ Experienced - f a s t e r migration compared to FM ( i e . more migrants w i t h i n the f i r s t hour) + - f a s t e r m igration compared to FM * 1 % MIGRANTS & % NON-MIGRANTS Fast Migrants -greater %'age of migrants compared to SM ++ -smaller %'age of migrants compared to predator troughs * 2 -smaller %'age of non-migrants compared to SM ++ -greater %'age of non-migrants compared to predator troughs ++ -smaller %'age eaten compared to SM Slow Migrants -smaller %'age of migrants compared to FM ++ -smaller %'age of migrants compared to predator troughs ++ -greater %'age of non-migrants compared to FM ++ -greater %'age of non-migrants compared to predator troughs ++ -greater %'age eaten compared FM — Experienced -greater %'age of migrants compared to FM + -smaller %'age of migrants compared to predator troughs ++ -smaller %'age of non-migrants compared to FM + -greater %'age of non-migrants compared to predator troughs ++ -smaller %'age eaten compared to FM + *1 -although experienced f r y migrated slower compared to FM, Channel Experienced f r y migrated i n a s i m i l a r p a t t e r n to FM. * 2 -approximately the same %'age of migrants i n predator and p r e d a t o r - f r e e troughs. ++ observed i n majority of experiments + observed i n some experiments seldom observed — never observed 47 experience. Regardless of the b a s i s f o r the d i f f e r e n c e s among i n d i v i d u a l f r y , i t i s a l s o c l e a r t h a t groups cf f r y with d i f f e r e n t experience are d i f f e r e n t l y a f f e c t e d by exposure to predators. fts mentioned, the predators i n some way evcke an 'awareness* (Ginetz, 1972) i n the f r y which a l t e r s t h e i r naive behavior p a t t e r n s . The f r y migrated downstream much more q u i c k l y when predators were present. The f r y apparently sensed the presence of predators i n the stream channels, and were e i t h e r 'chased' of 'spooked' downstream at an i n c r e a s e d r a t e compared to s i t u a t i o n s where predators are absent. The downstream migration of f r y may be only a d i s o r g a n i z e d array c f f r y swimming i n d i v i d u a l l y downstream, or, i n a coherent s c h o o l . I n t e r p r e t a t i o n of the r e s u l t s i n terms of s c h o o l i n g t e n d e n c i e s cf sockeye f r y r e s t s h e a v i l y upon t h i s l a s t p o i n t . That i s , are the i n c r e a s e d m i g r a t i o n r a t e s * with predators present, i m p l y i n g t h a t the f r y are m i g r a t i n g downstream i n s c h o o l s ? D i r e c t o b s e r v a t i o n s f o r c o n f i r m a t i o n are l a c k i n g , but aquarium experiments (Ginetz, 1972; p e r s o n a l l a b and f i e l d o b s e r v a t i o n s ) , tend to f a v o r the view that sockeye f r y i n the presence of predators form s c h o o l s . Thus the i n c r e a s e d migration speed i s a r e f l e c t i o n of the f r y response t o predator presence, and i s accomplished most probably i n s c h o o l s . Experience a l s o a f f e c t s f r y behavior; i n most cases, enhancing any tendencies noted f o r f a s t migrants. Ginetz (1972) reported t h a t f r y , which had migrated dcwn a predator stream, s u r v i v e d p r e d a t i o n , and were re-run through the same procedure, e x h i b i t e d h i g h e r s u r v i v a l r a t e s and an i n c r e a s e d migration speed 48 compared' to naive f r y migrating down a p r e d a t o r - f r e e trough. F u r t h e r , he suggested t h a t past experience cf a predator ( i . e . experienced f r y ) was more e f f e c t i v e than only awareness of predators i n i n c r e a s i n g s u r v i v a l of f r y i n predator channels ( i . e . naive f r y i n a predator t r o u g h ) . Experiment 2 - E f f e c t of D i f f e r e n t P r e dators and I i qht on Emerging Fry Methods And B e s u l t s To t e s t the hypothesis t h a t l i g h t enhances mutual a s s o c i a t i o n s of emergent f r y , hence development of s c h o o l i n g t e n d e n c i e s and a r e s u l t i n g i n c r e a s e d s u r v i v a l , a 3 x 2 x 3 f a c t o r i a l experiment was designed. Three f r y types ( f a s t migrants, slow migrants and experienced f r y ) were su b j e c t e d t o a constant l i g h t source (1500 f t - c ) f o r three set time p e r i o d s (0, 6 and 24 h o u r s ) , and a l l were exposed t c two c c n d i t i c r s (no predators and rai n b o w / w h i t e f i s h combination). Each l i g h t treatment ended one hour p r i o r t c the i n i t i a t i o n of an experimental t r i a l , during which the f i s h were at an ambient l i g h t i n t e n s i t y o f 0„01 f t - c . Predator troughs contained 2 rainbow t r o u t and 4 whitefish,. During treatments, the f r y were s t c r e d i n covered 10 g a l aquaria to reduce any f o r e i g n s t i m u l i ; and, were maintained a t normal stream temperatures. Since the n a t u r a l f r y mi g r a t i o n was almost complete, only one r e p l i c a t e o f the experiment was p o s s i b l e . Experimental methods and a n a l y s i s 49 were as p r e v i o u s l y d e s c r i b e d . As with p r e v i o u s experiments, there was a decreasing cumber cf f r y migrating downstream during the evening (Figure 22). A n a l y s i s of v a r i a n c e (Appendix X) showed the o v e r a l l m i g r a t i o n p a t t e r n ( i . e . the number of f r y migrating downstream per time p e r i o d s ) , plus 'time p e r i o d s x f r y type' (Figure 23) and 'time p e r i o d s x predators* (Figure 24) i n t e r a c t i o n s to be s i g n i f i c a n t . The 'time periods x f r y type' i n t e r a c t i o n term showed t h a t the f a s t and slow migrants were s i m i l a r , yet a s i g n i f i c a n t l y g r e a t e r percent of experienced f r y migrated downstream w i t h i n the f i r s t sampling p e r i o d . Predators i n c r e a s e d the percent o f f r y migrating downstream i n t i e f i r s t hour, r e s u l t i n g i n a s m a l l e r percentage c f non-migrants compared to the p r e d a t o r - f r e e troughs. With only one r e p l i c a t e , comparison of the i n d i v i d u a l treatments and f r y types was not s t a t i s t i c a l l y f e a s i b l e , hut a comparison o f the migration p a t t e r n s (Figure 25) i s e n l i g h t e n i n g . Ccmparing f i r s t the f r y typ e s , i n most cases there was a d i f f e r e n c e between the predator and p r e d a t o r - f r e e troughs. Fast migrants i n the predator channels migrated r a p i d l y downstream and there were fewer non-migrants. Slow migrants d i s p l a y e d a s i m i l a r t r e n d , but not as d i s t i n c t i v e l y as f a s t migrants. Experienced f r y , (except f o r cne t r i a l - the 24 hour l i g h t treatment f o r experienced f r y i n the predator channel) were as abrupt i n t h e i r migration p a t t e r n as f o r f a s t migrants. The e f f e c t o f l i g h t treatment was not c l e a r c u t . For the p r e d a t c r - f r e e troughs, the experienced f r y migrated r a p i d l y downstream within the f i r s t hour f o r a l l l i g h t treatments. When 5 0 0 . 5 h r s a m p l i n g p e r i o d s FIGURE 22: Mean m i g r a t i o n p a t t e r n o f e x p e r i m e n t a l f r y . • • f a s t m i g r a n t s • • s l o w m i g r a n t s * * e x p e r i e n c e d 0 . 5 h r s a m p l i n g p e r i o d s FIGURE 23: M i g r a t i o n p a t t e r n s o f e x p e r i m e n t a l f r y w i t h i n a r t i f i c i a l s t r e a m c h a n n e l s . P l o t o f 'time p e r i o d s x f r y t y p e ' i n t e r a c t i o n .from a n a l y s i s o f v a r i a n c e , A p p e n d i x X. — • p r e d a t o r s • -• n o p r e d a t o r s 0 . 5 h r s a m p l i n g p e r i o d s FIGURE 24: M i g r a t i o n p a t t e r n s o f e x p e r i m e n t a l f r y w i t h i n a r t i f i c i a l s t r e a m c h a n n e l s . P l o t o f 1 t i m e p e r i o d s x p r e d a t o r s ' i n t e r a c t i o n f r o m a n a l y s i s o f v a r i a n c e . A p p e n d i x X. (a) FAST MIGRANTS (b) SLOW MIGRANTS (c) EXPERIENCED 0 . 5 h r s a m p l i n g p e r i o d s 0 . 5 h r s a m p l i n g p e r i o d s ° - 5 h r s a m p l i n g p e r i o d s FIGURE 25: M i g r a t i o n p a t t e r n s o f e x p e r i m e n t a l f r y i n a r t i f i c i a l s t r e a m c h a n n e l s w i t h and w i t h o u t p r e d a t o r s . P r i o r t o e a c h e x p e r i m e n t , f r y were s u b j e c t e d t o d i f f e r e n t l i g h t t r e a t m e n t s . 52 predators were present the major part of the m i g r a t i o n o c c u r r e d e a r l y i n the evening. With slow migrants, and no predators present, the 6 and 24 hour treatments gave s i m i l a r r e s u l t s , but f r y subjected to no l i g h t (0 hour treatment) migrated at a slower r a t e and y i e l d e d approximately twice the number of non-migrants. Predators tended tc i n c r e a s e the m i g r a t i o n r a t e of slow migrant f r y , e s p e c i a l l y those subjected to no l i g h t , l i e .6 and 24 hour treatment f r y were s i m i l a r i n both predator and p r e d a t o r - f r e e troughs. The e f f e c t of l i g h t treatments on f a s t migrants was s i m i l a r i n a l l three cases, but with p r e d a t o r s , the percentage o f migrants i n the e a r l y evening i n c r e a s e d , and s i g n i f i c a n t l y fewer ncr-migrants r e s u l t e d . A n a l y s i s of the percent migrants in, the f i r s t hcur i s summarized i n Appendix XIa and F i g u r e 26. A n a l y s i s of v a r i a n c e and subsequent Duncan's New M u l t i p l e Eange Test showed c n l y the predator e f f e c t to be s i g n i f i c a n t . Further range t e s t s fcund a s i g n i f i c a n t d i f f e r e n c e between the 0 and 6 hour treatment, and the 0 and 24 hour l i g h t treatment. As the exposure to l i g h t was lengthened, the percent migrants w i t h i n the f i r s t hour became l e s s a f f e c t e d by the presence of predators. F u r t h e r , i n mcst cases, with approximately 6 hours of l i g h t , the percent migrants within the f i r s t hour reached a maximum. F i n a l l y , a n a l y s i s of v a r i a n c e and Duncan's New M u l t i p l e Bange Tests of the percent migrants (Appendix Xlb and F i g u r e 27) and percent non-migrants (Appendix XIc and F i g u r e 28) again showed only the predator e f f e c t t o be s i g n i f i c a n t . Although not 20 12 ie l i g h t t r e a t m e n t ( h r s ) FIGURE 26: P e r c e n t m i g r a n t s w i t h i n t h e f i r s t h o u r f o r e x p e r i m e n t a l f r y , s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s , m i g r a t i n g t h r o u g h a r t i f i c i a l s t r e a m c h a n n e l s w i t h and w i t h o u t p r e d a t o r s . 12 I B l i g h t t r e a t m e n t ( h r s ) FIGURE 27: P e r c e n t m i g r a n t s f o r e x p e r i m e n t a l f r y , s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s , m i g r a t i n g t h r o u g h a r t i f i c i a l s t r e a m c h a n n e l s w i t h and w i t h o u t p r e d a t o r s . e ° 40 p r e d a t o r s n o p r e d a t o r s f a s t m i g r a n t s s l o w m i g r a n t s , e x p e r i e n c e d 12 18 l i g h t t r e a t m e n t ( h r s ) FIGURE 28: P e r c e n t n o n - m i g r a n t s f o r e x p e r i m e n t a l f r y , s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s , m i g r a t i n g t h r o u g h a r t i f i c i a l s t r e a m c h a n n e l s w i t h and w i t h o u t p r e d a t o r s . 54 as d i s t i n c t as F i g u r e 26, (the percent migrants w i t h i n the f i r s t h our), the b a s i c t r e n d i s e v i d e n t f o r the percent migrants. The p r e d a t o r s , at the t h r e e l i g h t treatments, i n c r e a s e d the number of migrants, hence t h e r e were fewer non-migrants. The d i f f e r e n c e i n percent l o s t or eaten between the predatcr and p r e d a t c r - f r e e troughs was n e g l i g i b l e . l i s c u s s i o n As i n f o r e g o i n g experiments, the presence of p r e d a t o r s caused an i n c r e a s e i n the percentage of migrants i n the f i r s t hour, i n c r e a s e d the t o t a l percentage of migrants, and reduced the percent c f non-migrants. The g u e s t i o n of f r y response to i n c r e a s e d l i g h t treatments i s much more complex and d i f f i c u l t t c i n t e r p r e t , e s p e c i a l l y compounding i t with the three f r y t y p e s . From the a n a l y s i s of the percent migrants w i t h i n the f i r s t hour, i t appears t h a t as the f r y are s u b j e c t e d to a longer l i g h t treatment p r i o r t o an experiment, the percentage of migrants i n c r e a s e d . T h i s was a l s o noted f o r the t o t a l percent of migrants. With the s i x hour l i g h t treatment, the reverse trend was observable, the percent o f migrants (within the f i r s t hour and t o t a l l y ) decreased, while the percent of non-migrants i n c r e a s e d . Since f r y - t o - f r y a s s o c i a t i o n s ( s c h c c l s ) are enhanced by v i s u a l c l u e s (Breder 1951,1967; Morrow 1948; Shaw 1960), i t i s p o s s i b l e t h a t as the l i g h t treatments i n c r e a s e , f r y may tend to form a s s o c i a t i o n s , o r i e n t i n g and f a m i l i a r i z i n g themselves with the surrounding environment. With only a few hours of l i g h t , and 55 the i n t r o d u c t i o n of a predator, the f r y r e a c t i o n may te t c group and move r a p i d l y downstream. However, when the f r y have been subjected to 24 hours l i g h t , the s c h o o l i n g behavior may have been s u f f i c i e n t l y r e i n f o r c e d , t h a t s c h o o l s form as a coherent group, which migrates downstream at a slower pace. Since f i e l d h e h a v i o r a l o b s e r v a t i o n s are l a c k i n g , these p o s t u l a t i c n s are su b j e c t to f u r t h e r study. Although the d i f f e r e n t f r y types f o r both percent migrants i n the f i r s t hour and percent migrants/percent non-migrants were not shown to be s i g n i f i c a n t , some trends are e v i d e n t . With no p r e d a t o r s , and no l i g h t treatment, the decreasing order of numbers migrating was as noted p r e v i o u s l y : experienced, f a s t migrants, and slow migrants. As the f r y were i n c r e a s i n g l y s u b j e c t e d t o l i g h t , experienced f r y tended i n i t i a l l y to i n c r e a s e the percentage m i g r a t i n g . Assuming the cne r e p l i c a t e i s i n d i c a t i v e of what i s a c t u a l l y happening, i t appears that the l i g h t treatment enhances the percentage of slow migrants moving downstream, suggesting that the l i g h t treatment i s a component a f f e c t i n g the migrati o n p a t t e r n by i n c r e a s i n g s c h c c l i n g t e n d e n c i e s . With predators present, experienced f r y subjected to no l i g h t migrated downstream f i r s t . The same was true f o r f a s t and slew m i g r a n t s , , A f t e r 6 hours of l i g h t , the f a s t migrants and experienced f r y migrated at the same r a t e , the l i g h t treatment p o s s i b l y a c t i n g on the f a s t migrants a d d i t i v e l y with the presence of p r e d a t o r s , r e i n f o r c i n g the tendency f o r a r a p i d downstream mi g r a t i o n . However a f t e r 24 hours c f l i g h t exposure, the percent migrants w i t h i n the f i r s t hour f o r the t h r e e f r y 56 types were sim i l a r and approximately one-third l e s s , compared to the 0 and 6 hour l i g h t treatments. This suggests that a f t e r a certain period of l i g h t exposure, the differences i n f r y types become ne g l i g i b l e ; the behavioral interactions occurring during the extended period of l i g h t overcome early experiences and/or differences in the fry type. 57 SECTION C: DEVELOPMENT OF SCHOOLING BEHAVIOR Experiment J - F r y Response t o L i g h t M a t e r i a l And Methods Male and female salmon roe was c o l l e c t e d from F u l t o n B i v e r . C o l l e c t i o n , f e r t i l i z a t i o n and i n c u b a t i o n procedures are d e t a i l e d i n Appendix XII. Experiments were conducted i n a gridded (10x18.3 cm by 4x11.4 cm) 1.83 m s e c t i o n of a l a r g e r f i b e r g l a s s stream tank. The tank was designed as a flow-through system, the water depth maintained at 30 cm, t i e v e l o c i t y at approximately 0.13 cm/sec, and a temperature of 4.0 ± 1.0° C. Ti e experimental procedure c o n s i s t e d of ta k i n g 50 f r y from the storage tanks and a c c l i m a t i n g them.in the stream"channel f o r 15 minutes i n the dark. F o l l o w i n g a 'treatment', the experimental chamber was darkened f o r one hour, then the f r y were observed under 0.1 f t - c f o r 10 minutes. The treatment c o n s i s t e d of s u b j e c t i n g d i f f e r e n t groups of f r y t o 4.0 - 12.0 f t - c l i g h t i n t e n s i t y f o r v a r y i n g time p e r i o d s , from 30 seconds to 24 hours. Three-dimensional c o o r d i n a t e s of the f i s h were determined by o b s e r v a t i o n through the g l a s s s i d e s , and a m i r r c i suspended at approximately 45° above the tank. T y p i c a l l y , at the onset o f o b s e r v a t i o n the f r y were randomly d i s t r i b u t e d and s o l i t a r y on 58 the tank bottom. Within a short time the f r y became a c t i v e and i n i t i a t e d s c h o o l i n g t e n d e n c i e s . P r i o r to t h i s a c t i v i t y the f r y were recorded as i n d i v i d u a l s w i t h i n each of the 10 lengthwise s e c t i o n s ; however, once movement commenced the a c t i v i t y was recorded as the time taken to swim the l e n g t h cf the tank. a n a l y s i s examined fo u r parameters: (1) swimming time, or a c t i v i t y , (time s t a r t e d when at l e a s t 25% i n i t i a t e d movement towards one end of the tank, and ended when g r e a t e r than 75% of the f r y reached the other end); (2) r e s t i n g time, or t u r n i n g t i n e , (the time between reachi n g an end and s t a r t i n g towards the other end); (3) school length d u r i n g swimming (measured by the g r i d ) ; and (4) time taken to form s c h o o l (at l e a s t 90% c f the f r y i n a swimming, u n i - o r i e n t e d group). S t a t i s t i c a l l y , the data were d i v i d e d i n t o f o u r treatment groups (0 - 3 h r s . , 3+ - 6 h r s . , 6+ - 9 h r s . , and 9+ - >24 h r s . ) , with a n a l y s i s of variance and Duncan's New M u l t i p l e Bange Test a p p l i e d t o t e s t d i f f e r e n c e s . B e s u l t s P r e l i m i n a r y o b s e r v a t i o n s of f r y behavior under experimental c c n d i t i o n s are summarized i n Table VII., although subseguent experiments employed d i f f e r e n t time frames per t r i a l , the g e n e r a l i z e d behavior p a t t e r n s were s i m i l a r . Table V I I I summarizes the a n a l y s i s of the f o u r measured parameters. Swimming time (Table V i l l a ) was the most i n f o r m a t i v e v a r i a b l e measured. A n a l y s i s of v a r i a n c e found the f i v e treatment groups to be s i g n i f i c a n t l y d i f f e r e n t ; a Duncan's New M u l t i p l e 59 IfiELj V II: Summary of b e h a v i o r a l o b s e r v a t i o n s f o r f r y under experimental c o n d i t i o n s d i s c u s s e d w i t h i n t e x t . INTRODUCTION TO TRNK (Darkness) IEY SHOCKED LIGHTS • ON * LIGHTS •OFF' - f r y swim t o bottom; remain s t a t i o n a r y f o r 0.5-6 min - s l o w l y s t a r t n o n - d i r e c t i c n a l movement; approx. 105? remain s t a t i o n a r y - w i t h i n 15-20 min loose groups forms, swimming le n g t h of tank -movement i n c r e a s e s ; t i g h t e r grcup fcrm (school) with u n i d i r e c t i o n a l movement, - w i t h i n 35-45 min, movement decreases and f r y spread out cn bottcm -throughout t h i s p e r i o d , f r y remain i n lower t h i r d o f water column - f r y r a p i d l y d i s p e r s e as a very l o o s e group - w i t h i n 3-5 min group slows down and d i s t r i b u t e s over the bottcm - t i g h t group forms within 15 sec i n f u r t h e s t c o r ner frcm l i g h t source - w i t h i n 1-2 min, f r y r a p i d l y swimming l e n g t h of tank i n a s c h o o l , and have moved to. the upper t h i r d of tank - w i t h i n 5-10 min, the s c h c c l s l o w l y d i s p e r s e s and movement decreases - t i g h t group forms i n water column and a l l movement stops ^ f o r 1-2 min group remains motionless, then slowly descends t o lower t h i r d of tank and f r y d i s p e r s e - w i t h i n 5-7 min f r y slo w l y s t a r t movement as noted above f o l l o w i n g i n t i c d u c t i c n to tank i r  60 TABLE V I I I : Summary of a n a l y s i s f o r f r y observed f o l l o w i n g v a r i a b l e l i g h t treatments. Measured parameters d e s c r i b e d w i t h i n t e x t . r — T ! 1 | TREATMENT GROUPS | SKCVA | 0 hrs | 0+ > | 3+ > | 6+ •> 19 + > l (Fcalc) | 3hrs | 6hrs | 9hrs | >24hrs| j I I I a- SWIMMING TIME (sees) Mean Stan, e r r o r Sample s i z e 18.69 0.37 4 24.77 1.74 14 35,. 85 2.36 5 31.50 2.33 2 27.74 1.41 3 6.62 REJECT Ho E.N.M.R.T. I I 10.18 | 1.73 1.08 | ACCEPT 3 I Ho b. RESTING TIME (sees) Mean Stan, e r r o r Sample s i z e I I 16.04 | 0.84 4 I I I 16.06 | 1.26 | 14 I I I 18.67 | 3.44 | 5 I 12. 14 0.69 2 E.N.M.R.T. *c. SCHOOL LENGTH* 1 Mean Stan, e r r o r Sample s i z e Y E.N.M.R.T. I I 3. 18 | 0.48 | 4 I I I 3.3 0 | 0.36 | 14 I I 3.91 | 0.51 I 5 I I 3.99 | 0.42 | 2 I 3.4 3 0.46 2 0.40 ACCEPT Ho . r 1 L I __. d. TIME taken to FORM SCHOOL (sec) — — — — — * Mean Stan, e r r o r Sample s i z e 38.50 4.63 4 54. 44 4.37 9 I I 66.80 |125.00 7.96 | 45.00 5 I 2 KE0SKAL-WAI1IS * 2 (Hcalc) 23.00 4.04 3 7.42 ACCEPT Ho D.N. M.R.T. D.N.M.E.T. = Duncan's New M u l t i p l e Range Test (Underscored means are not s i g n i f i c a n t l y d i f f e r e n t ) ANOVA = A n a l y s i s of variance t e s t i n g h y p o t h e s i s (Ho) that mean values f o r treatment groups are not d i f f e r e n t * i s c h o o l l e n g t h was measured cn g r i d as number of sguares (1 square=18.3 cms) * 2 Ncn-paramentic a n a l y s i s of variance 6 1 Range Test showing both the c o n t r o l (0 hrs.) and frcm 3+ to 9 hours treatments s i g n i f i c a n t l y d i f f e r e n t compared to the remaining groups. Hence the swimming time ( i . e . time taken t o swim le n g t h of tank) i n c r e a s e d t o a maximum between four to s i x hours, then g r a d u a l l y decreased over the next 24 hours (Figure 29) . A n a l y s i s of v a r i a n c e showed no s i g n i f i c a n t d i f f e r e n c e s between treatment groups f o r both r e s t i n g time (Table V I I I t ) and sc h o o l l e n g t h (Table V I I I c ) . Although s t a t i s t i c a l l y not a p p r o p r i a t e , subsequent Duncan's New M u l t i p l e Eange T e s t s can account f o r the trends e v i d e n t i n F i g u r e s 30 and 31. The r e s t i n g time decreased over the 24 hour treatment p e r i o d , which corresponds t c an i n c r e a s e i n a c t i v i t y , ( i . e . a decrease i n swimming t i m e ) , with g r e a t e r than 6 hour treatments.. School l e n g t h maximized between the three to nine hours of l i g h t treatments, being s i g n i f i c a n t l y lower with g r e a t e r or l e s s time c f treatment. However, s i n c e the c a l c u l a t e d F value i n the a n a l y s i s of v a r i a n c e i s low compared t o the t a b u l a t e d v a l u e , i t i s best assumed t h a t the mean s c h o o l l e n g t h s are e s s e n t i a l l y s i m i l a r . The estimated time taken t o form a sc h o o l (Table V l l l d ) v a r i e d c o n s i d e r a b l y wi t h i n treatment grcups, r e s u l t i n g i n he t e r o g e n e i t y of v a r i a n c e . Non-parametric a n a l y s i s c f v a r i a n c e , ( K r u s k a l - W a l l i s Test) , r e j e c t e d the n u l l h y p o t h e s i s o f s i n i l a r i t y of means f o r the f i v e treatment groups; a Duncan's New M u l t i p l e Range Test showed o n l y the 0+ t c s i x hour treatment groups not s i g n i f i c a n t l y d i f f e r e n t . A r e l a t i o n s h i p (Figure 32) i s d i f f i c u l t t o f i n a l i z e because of the l a r g e v a r i a n c e recorded 50 40 30 r 20 10 >24 h r s 6 8 10 l i g h t t r e a t m e n t (hrs) 12 24 FIGURE 29: SWIMMING TIME- t i m e t a k e n ( s e c o n d s ) t o swim l e n g t h o f e x p e r i m e n t a l tank f o r f r y s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s . C u r v e f i t t e d by p o l y n o m i a l r e g r e s s i o n . FIGURE 30: RESTING TIME- t i m e t a k e n ( s e c o n d s ) t o t u r n a t end o f t a n k f o r f r y s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s . C u r v e f i t t e d by p o l y n o m i a l r e g r e s s i o n . 6 FIGURE 31: SCHOOL LENGTH- l e n g t h o f s c h o o l (measured by g r i d ) d u r i n g swimming f o r f r y s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s . C u r v e f i t t e d by p o l y n o m i a l r e g r e s s i o n 160 '3 hrs 3+ »6 hrs 6+ »9 hrs 9+ »>24 hrs 6 8 10 l i g h t treatment (hrs) 12 24 FIGURE 32: SCHOOL FORMATION- t i m e t a k e n ( s e c o n d s ) t o form s c h o o l f o r f r y s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s . C u r v e f i t t e d by p o l y n o m i a l r e g r e s s i o n . 64 f o r the s i x to nine hour treatment, yet some trends are e v i d e n t . Eoth c o n t r o l and g r e a t e r than nine hours l i g h t treatment r e s u l t e d i n l e s s time taken to form a s c h o o l . Experiment 2 - E f f e c t o f L i g h t and Fry D e n s i t i e s on Schooling Behavior M a t e r i a l And Methods Three components i n v o l v e d with i n i t i a t i o n and maintenance of a s c h o o l are: (1) a c e r t a i n number of f i s h must be i n c l o s e p r o x i m i t y ; (2) some l i g h t must be a v a i l a b l e f o r v i s u a l communication; and (3) time i s r e q u i r e d to develop s k i l l s of s c h o o l i n g . The f o l l o w i n g experiments attempted to examine the importance of these three f a c t o r s i n the i n i t i a t i o n c f s c h o o l i n g t e n d e n c i e s i n sockeye f r y . The r e s u l t s provided o n l y l i m i t e d i n f o r m a t i o n to t h i s end. S i m i l a r to the foregoing lab study, salmon roe were c o l l e c t e d at F u l t o n R i v e r , with f e r t i l i z a t i o n and i n c u b a t i o n at the U n i v e r s i t y of B r i t i s h Columbia. A l l procedures i n v o l v e d with the l a t t e r were f o l l o w e d as p r e v i o u s l y d e s c r i b e d . Due tc high m o r t a l i t y (ca. 80%) e a r l y i n the i n c u b a t i o n phase, a second batch of roe was c o l l e c t e d from sockeye salmon spawning i n Weaver Creek, B.C.. Once a l l f r y were s u f f i c i e n t l y developed, (stage 5 of development, Ginetz 1972), they were t r a n s f e r r e d frcm the i n c u b a t i o n t r a y s t o darkened 227 l i t r e f i b e r g l a s s storage tubs. 65 Experiments were conducted i n a gridded (15 x 9 x 9 sguares; each square = 27 mm2) 10 g a l aquarium (Figure 33), with a m i r r o r suspended overhead a t 45° f o r a 3-dimensional aspect. P r i o r to each experiment the tank was f i l l e d with water, temperature throughout the f u l l e x perimental period ranging from 8 - 14.5° C, (although v a r y i n g only a few degrees per o b s e r v a t i o n ) , and oxygen l e v e l s maintained at 13 - 14 ppm. ft se t number of f r y were placed i n the tank and a c c l i m a t i z e d f o r 20 minutes before each l i g h t treatment. Treatments c o n s i s t e d of s u b j e c t i n g the f r y t c a set p e r i o d of l i g h t i n t e n s i t y (ca. 15 - 30 f t - c ) , ranging from 0 to 12 hours, f o l l o w i n g which the f r y recuperated f o r 30 minutes i n the dark and were then observed f o r a 30 minute p e r i o d under low l i g h t i n t e n s i t y (4.5 - 5.0 f t - c ) . The 3-dimensional c o o r d i n a t e s and compass d i r e c t i o n o f the f r y were determined every 10 seconds f o r the 30 minute p e r i o d , noted on a tape r e c o r d e r , and l a t e r decoded f o r a n a l y s i s (Figure 34). The d i s t a n c e f r y moved w i t h i n each time period was c a l c u l a t e d by t a k i n g the square root of x 2 + y 2 + z 2 ; x, y, and z being the 3-dimensicnal c o o r d i n a t e s . Observing g r e a t e r than t h r e e f i s h presented a problem f o r r e c o r d i n g the 10 second movements, thus one f i s h , with normal a c t i v i t y p a t t e r n s , out of the group was observed f o r the time p e r i o d . A second approach was to record the behavior of the f i s h as a group throughout the o b s e r v a t i o n p e r i o d . 66 IIGOEE 34: Experimental tank, c o n t a i n i n g f r y , as seen during o b s e r v a t i o n p e r i o d . 67 E e s u l t s T y p i c a l l y , as f r y were subjected to i n c r e a s i n g p e r i o d s o f l i g h t treatment t h e i r movement p a t t e r n s were e s s e n t i a l l y s i n i l a r . A p a r t i c u l a r example, the movement of one f r y i n a group of ten was observed f o r a 6 hour treatment peri o d and a f u r t h e r h a l f hour f o l l o w i n g the r e c u p e r a t i o n p e r i o d (Figure 35). The f r y remained r e l a t i v e l y motionless a f t e r i n t r o d u c t i o n to the darkened aguaria. Once the l i g h t treatment began the f r y g r a d u a l l y s t a r t e d moving and they reached a maximum withir- the f i r s t hour, Subseguently, the movement was minimal. Dependent upon the l e n g t h of l i g h t treatment, the amount cf movement f o l l o w i n g the dark r e c u p e r a t i o n p e r i o d i n c r e a s e d , then a c t i v i t y e i t h e r remained constant or decreased w i t h i n the 30 min o b s e r v a t i o n . To i n t e r p r e t the e f f e c t of i n c r e a s i n g the time p e r i o d of l i g h t treatment, plus i n c r e a s i n g the number cf f r y , a n a l y s i s of v a r i a n c e (and a Duncan's New M u l t i p l e Bange Test) was computed f o r the two s t a t i s t i c s : the mean amount of movement per 30 min o b s e r v a t i o n p e r i o d , and, the time taken to s t a r t swimming f o l l o w i n g dark r e c u p e r a t i o n . For a n a l y s i s the r e s u l t s were blocked as f o l l o w s : (A) 0 - 1 hr, 1 - 3 f r y ; (B) 3 - 6 hr, 1 - 3 f r y ; (C) 0 - 1 hr, 10 - 30 f r y ; (D) 3 - 6 h r , 10 - 30 f r y . A n a l y s i s of mean movement (Table IXa) shewed a s i g n i f i c a n t d i f f e r e n c e between the fo u r s e c t i o n s except f o r b l o c k s •A' and •E', ( i . e . fewer f r y during both time p e r i o d s ) . The s t a r t i n g times (Table IXb) l i k e w i s e were s i g n i f i c a n t l y d i f f e r e n t , but f o r blo c k s »C* and •D *, ( i . e . the g r e a t e r number of f r y during both 68 FIGURE 3 5 : D i s t a n c e moved by one f i s h i n a g r o u p o f t e n f r y . E a c h s q u a r e i s t h e mean movement f o r a 10 m i n u t e o b s e r v a t i o n p e r i o d . Shaded a r e a r e p r e s e n t s d a r k r e c u p e r a t i o n p e r i o d . 69 TAELF IX: E e s u l t s from a n a l y s i s of va r i a n c e and Duncan's Hew M u l t i p l e Eange l e s t f o r : (a) mean movement per 30 min o b s e r v a t i o n p e r i o d , and (b) time taken to s t a r t swimming f o l l o w i n g dark r e c u p e r a t i o n . Data was blocked as d e s c r i b e d w i t h i n t e s t . Underscored means are net s i g n i f i c a n t l y d i f f e r e n t . (.§) Mean movement per 3 0 min ob s e r v a t i o n p e r i o d : | Source of V a r i a t i o n | DF | | T o t a l j Among I Within SS I MS I | 51 | 1144.15 | | | 3 | 320.62 | 106.87 | | 48 | 823.53 | 17.16 | I 6.23 ** | I D.N.M.E.T. B Mean Variance 9.92 4.63 8.91 5.05 12.74 3. 16 5. 10 2. 36 N.S. (b) Time taken to s t a r t swimminq: | Source of V a r i a t i o n | DF | SS I MS I I | T o t a l j Among | Within l _ : _ l 1 . L -+ h V 1-| 50 | 1C06.00 | | I 3 | 618.97 | 206.32 | 25.07 | 47 | 387.03 | 8.23 | I — ^ I * * I I D.N.M.E.T. B Mean Variance 2. 87 3.72 5.38 37.98 0. 67 1, 32 1.64 2.62 N. S. 70 time p e r i o d s ) . Both these analyses and o b s e r v a t i o n of the movement patt e r n s (Figure 36) tended t c show a decreased movement when there were more f r y present, and when f r y were subjected t o g r e a t e r p e r i o d s of l i g h t treatment. I n t e r p r e t i n g the e f f e c t of l i g h t treatment cn f r y numbers, i t appears t h a t g r e a t e r movement was c o r r e l a t e d with fewer hours of l i g h t treatment. In most cases, the 3 hour treatment r e s u l t e d i n l e s s movement; however, f u r t h e r 6 hour measurements i n the same manner are needed t o s u b s t a n t i a t e t h i s t r e n d . B e h a v i o r a l o b s e r v a t i o n s of the f r y c o r r e l a t e with the preceding. With 2 or 3 f i s h i n the tank, once movement begins, the f r y s t a r t out i n c l o s e p r o x i m i t y , (ca. 0.5 - 1.0 sguares a p a r t ) . T h e i r d i s t a n c e apart i n c r e a s e s with time yet i s u s u a l l y never greater than by 3 squares. I f t h i s d i s t a n c e i s exceeded, cne w i l l q u i c k l y reapproach the other. Greater numbers of f r y i n the tank d i s p l a y a s i m i l a r p a t t e r n but the i n t e r a c t i o n between 2 or 3 i n d i v i d u a l f i s h i s not as i n t i m a t e . U s u a l l y 2 - 3 f i s h w i t h i n 2 squares and o r i e n t a t i n g i n the same d i r e c t i o n w i l l maintain themselves as a group. However, i f another i n d i v i d u a l or group c l o s e l y passes by i n the same h o r i z o n t a l plane, cne or more of the f r y from the o r i g i n a l group may j o i n up with the passing f i s h . As the number of f i s h i n c r e a s e s i n the tack, the main d i f f e r e n c e i s an i n c r e a s e i n the number c f f r y per group; such that with 15 f r y the groups, are u s u a l l y 2 f r y , and with 30, u s u a l l y 3 - H f r y per group. 7 1 FIGURE 36: Movement p a t t e r n s o f d a r k - a d a p t e d f r y , s u b j e c t e d t o v a r y i n g t i m e p e r i o d s o f l i g h t t r e a t m e n t . O b s e r v a t i o n t i m e shown on t h e a b s c i s s a , e a c h mark a 5 m i n u t e i n t e r v a l . O r d i n a t e shows f r y movement; a x i s d i v i d e d i n t o u n i t s o f 5. E a c h c u r v e i s a s e p a r a t e e x p e r i m e n t , w i t h t h e e x c e p t i o n o f 2 and 3 f r y where e a c h g r a p h r e p r e s e n t s an e x p e r i m e n t w i t h movement r e c o r d e d f o r a l l f r y . l i g h t t r e a t m e n t 0 min 3 0 min 3 h r 6 h r 1 fry : 1 fry 2 fry -- -• 2 fry T— 1 E * * * »• L - • • • V C E V E I" • S * E E 4- fc-3 fry -• * - ^ ^ V S S" S E fc-3 fry I- - " \— c s *• *• • . k > 4 4V » 10 fry -20 fry 3 0 fry -3 0 fry * J s » * » 72 D i s c u s s i o n In the f i r s t experiment, s u b j e c t i n g 'newly emerged* f r y t o v a r y i n g p e r i o d s of l i g h t i n t e n s i t y changed t h e i r b ehavior. Since these f r y had been kept i n the dark from h a t c h i n g , i t c o u l d be assumed t h a t they resembled f r y emerging frcm the g r a v e l f o r the f i r s t time. as summarized i n F i g u r e 37, a n o t i c e a h l e change occurs with time taken to swim the l e n g t h of the o b s e r v a t i o n tank, n e a r l y a t w o - f o l d i n c r e a s e when the f r y were held under s i x hours of l i g h t compared to those s u b j e c t e d to no l i g h t p r i o r to o b s e r v a t i o n . Time taken t c form a s c h o o l f e l l o w s a s i m i l a r p a t t e r n , suggesting that f r y with no previous l i g h t experience r e a d i l y form a school and, maintain a r a p i d * s e a r c h i n g ' pace. T h i s p o s s i b l y r e f l e c t s an i n n a t e tendency t c form a s s o c i a t i o n s i n the absence of p r i o r v i s u a l s t i m u l a t i o n , p l u s , the e x p l o r a t o r y and 'nervous' behavior the f r y are e x p e r i e n c i n g under new e x t e r n a l - c o n d i t i o n s . As the l i g h t treatment i n c r e a s e s the f r y may be more f a m i l i a r with t h e i r surroundings, having had s i x c r more hours to explore and accustom themselves; hence swimming time and time taken to s c h o o l are both l o n g e r . With 24 hours l i g h t , the swimming time i s somewhat l e s s , , b u t the s c h o o l i n g time i s much reduced - h a l f t h a t of f r y s u b j e c t e d to no l i g h t , and o n l y a t h i r d compared t o those f r y subjected t c s i x hcurs of l i g h t . T h i s suggests t h a t the f r y become more e f f i c i e n t i n developing a s c h o o l . The d i f f e r e n c e i n s c h o o l i n g time between f r y with no previous experience of l i g h t and those with g r e a t e r than 12 hours may be a r e f l e c t i o n of the s t r u c t u r a l a r r a y of the s c h o o l ; 73 FIGURE 3 7 : Summary o f r e s u l t s f o r f r y s u b j e c t e d t o v a r i o u s l i g h t t r e a t m e n t s . Shaded a r e a r e p r e s e n t s d e g r e e o f u n c e r t a i n t y on c u r v e between t h e two p o i n t s f o r t i m e t a k e n t o f o r m s c h o o l . S o u r c e o f c u r v e s f u l l y e x p l a i n e d w i t h i n t h e a p p r o p r i a t e s e c t i o n o f t e x t , l a b o r a t o r y e x p e r i m e n t no. 1. 74 l e s s time i s needed t o form a coherent, s t a b l e group. A l s c , as f r y are s u b j e c t e d to longer p e r i o d s of l i g h t resembling d i u r n a l c y c l e s , n a t u r a l rhythms may develop which i n c r e a s e t h e i r s c h o o l i n g e f f i c i e n c y . The second experiment showed t h a t i n c r e a s i n g both the d u r a t i o n of l i g h t treatment and the number of f i s h , a l t e r e d behavior p a t t e r n s of the f r y such t h a t movement or swimming time was reduced. This i n p a r t c o r r e l a t e s with the ob s e r v a t i o n s i n the previous experiment. However, two shortcomings i n the experimental design hinder too c l o s e a comparison: (1) too few r e p l i c a t e s f o r the longer l i g h t treatments; and (2) a p o s s i b l e tank e f f e c t as the number of f r y are i n c r e a s e d , so t h a t behavior w i l l not resemble t h a t found i n the f i r s t experiment due to the c o n f i n e s of the s m a l l e r o b s e r v a t i o n tank. E e h a v i o r a l o b s e r v a t i o n s were s i m i l a r tc those r e p o r t e d i n other s t u d i e s (Healey 1972; Hemmings 1966; Hear 1954; John 1964; Keenleyside 1955; Steven 1959). G e n e r a l l y i t was found t h a t s c h o o l i n g j u v e n i l e f i s h , i n t r o d u c e d to an i l l u m i n a t e d tank, maintained the s c h o o l by a balance between the tendency of i n d i v i d u a l f i s h to depart, and, the mutual a t t r a c t i o n of f i s h to ones' own kind (Steven 1959). T h i s behavior r e s u l t s i n three b a s i c motor p a t t e r n s : (a) E x p l o r a t o r y tendency - f i s h swimming away frcm the group; (b) Returning tendency - f i s h swimming away frcm group r e t u r n i n g , i f not f o l l o w e d ; and (c) F o l l o w i n g tendency - f i s h f o l l o w i n g others swimming away from group (Hemmings 1966). Both l a b s t u d i e s h e r e i n r e p o r t e d fcund these behavior p a t t e r n s g e n e r a l l y apparent. Two d i f f i c u l t i e s r e s u l t from t h i s type cf l a b work. F i r s t , 75 i t i s d i f f i c u l t t o e x t r a p o l a t e aquarium s t u d i e s t o the n a t u r a l environment. F i s h i n nature are subjected to a c o n t i n u a l array cf d i f f e r e n t f r i g h t s t i m u l i ; i n comparison, the l a b i s a monotonous s e t t i n g . For example, i t was shown t h a t s c h o o l i n g behavior i n the aquarium changes with time (Jchn 1S6U) . F o l l o w i n g i n t r o d u c t i o n , compact s c h o o l s are formed, but a f t e r an e x p l o r a t o r y p e r i o d the f i s h gain 'confidence' and s c a t t e r throughout the tank. Secondly, comparison between la b s t u d i e s i s a l s o hazardous. Healey (1972) found t h a t although the average behavior f o r grouped and i n d i v i d u a l f i s h was approximately the same, f i s h i n a group swam more compared to i s o l a t e d i n d i v i d u a l s . T h i s i s i n c o n t r a s t t o the r e s u l t s from the second lab experiment i n t h i s study. However, d i f f e r e n t experimental c o n d i t i o n s and equipment can produce v a r y i n g r e s u l t s . 76 DISCUSSION a. Summary, of E e s u l t s In summary, the r e s u l t s showed t h a t : (1) the number of f r y moving downstream v a r i e s throughout the n i g h t l y m i g r a t i o n p e r i o d ; (2) emergent f r y are not a l l s i m i l a r i n t h e i r migratory behavior, some tend to migrate r a p i d l y ( f a s t migrants), while others migrate at a slower r a t e (slow migrants); (3) the migration p a t t e r n , and the percentage c f migrants and ncE-migrants, i s s i g n i f i c a n t l y a f f e c t e d by the presence of predators; (4) predators tend to i n c r e a s e the r a t e of downstream f r y m i g r a t i o n ; (5) the presence of any predator i s s u f f i c i e n t t o e l i c i t the above behavior m o d i f i c a t i o n s , the f r y response tends not to be p r e d a t o r - s p e c i f i c ; (6) i n most cases, f r y with p r i o r experience t c predators d i s p l a y e d d i f f e r e n t migratory behavior compared to f a s t and slow migrants; and (7) s u b j e c t i n g newly-emerged f r y to l i g h t a l t e r s behavior p a t t e r n s . These p o i n t s w i l l be subsequently d i s c u s s e d . J - j a r l y L i f e H i s t o r y of Sockeye Fry This study d e a l t with a comparatively short phase i n the l i f e c y c l e of sockeye f r y - emergence to downstream movement, i n which a number of d i s c r e t e stanzas can be d e f i n e d : 77 1,. Hatching to i n i t i a t i o n of emergence; 2. I n i t i a t i o n o f emergence to emergence; 3. Emergence from g r a v e l i n t o the water column; 4. Downstream (or upstream) displacement; and f i n a l l y , ' 5. Pool or stream r e s i d e n c e f o r a s h o r t p e r i o d , and/or lake e n t r y . fit each stage a complex s e r i e s of e x t e r n a l environmental s t i m u l i and i n t e r n a l b i o t i c f a c t o r s i n t e r a c t to r e g u l a t e and i n f l u e n c e developmental and b e h a v i o r a l changes oc c u r i n g with r e s p e c t t o the f r y (Bams, 1969). Fo l l o w i n g a p e r i o d of i n c u b a t i o n , c l o s e l y dependent upon amtient water temperatures, f r y hatch and g u i c k l y wiggle deeper i n t o the g r a v e l i n t e r s t i c e s . T h i s behavior r e s u l t s from an innate negative p h o t o t a c t i c response (Bams, 1969). fts yelk r e s e r v e s are d e p l e t e d , the f r y commence movement to the g r a v e l s u r f a c e , t e n d i n g t o move i n waves, as would be expected with v a r i a t i o n i n hatching time. During emergence, each wave cf f r y accumulates j u s t below the s u r f a c e of the g r a v e l . The t i m i n g of emergence i s c l o s e l y tuned t o low l i g h t and high water temperatures at dusk (Bams, 1S69). As l i g h t i n t e n s i t y decreases, i t s i n h i b i t o r y e f f e c t i s reduced, and the f r y emerge frcm the g r a v e l (Bams 1969; Heard 1965; Hoar 1953, 1954,1956, 1958; McEcnald 1960, Neave 1955). In a' short time, u s u a l l y a matter of a few hours, the peak wave has emerged. G e n e r a l l y , downstream movement i s c o n f i n e d to the p e r i o d dusk to dawn, with the g r e a t e s t numbers migrating during the d a r k e s t hours c f the n i g h t (Hartman et a l . 1962). As dawn approaches, i n c r e a s i n g l i g h t i n t e n s i t i e s and low water temperatures i n h i b i t f u r t h e r emergence. A f t e r emergence, the mode of downstream displacement i s not w e l l known: f r y are swept p a s s i v e l y downstream, swim a c t i v e l y 78 with the c u r r e n t , or do something inbetween. For passive movement i t was p o s t u l a t e d (Hoar 1951, 1953, 1S54, 1958; Johnson 19€5; Bams 1969; Byrne 1S71) t h a t r h e o t a x i s i s dependent upon v i s u a l and mechanical s t i m u l i with r e s p e c t t c f i x e d o b j e c t s , at n i g h t , a r e d u c t i o n i n l i g h t i n t e n s i t y i n the deeper waters causes the f r y to r i s e t o the s u r f a c e , l o s e v i s u a l c o n t a c t with the bottom, and hence to be d i s p l a c e d downstream. Furt h e r work, ( a i i 1959; B r e t t S a i i 1958) suggested t h a t f r y ccmmence downstream m i g r a t i o n i n a s t a t e o f p a r t i a l r i g h t b l i n d n e s s . at dusk, the r a t e of ambient l i g h t i n t e n s i t y e x t i n c t i o n i s g r e a t e r than the r a t e of dark-adaptation..Fry are d i s p l a c e d downstream u n t i l d ark-adaptation i s complete and they are a b l e to maintain p o s i t i o n i n r e l a t i o n t o r e f e r e n c e p o i n t s . On the other hand, f i e l d o b s e r v a t i o n s cn sockeye and pink f r y ( P r i t c h a r d 1944; Neave 1955; Hartman, e t a l . 1962, 1967) i n d i c a t e t h a t f r y f a c e downstream and swim f a s t e r than the c u r r e n t - thus t h e r e i s an a c t i v e displacement. Erannon (1972) concluded t h a t sockeye f r y emerging and mcving downstream appeared to have an o r i e n t e d r h e o t a x i s , using means other than v i s u a l s t i m u l i . F u r t h e r , the r h e o t a c t i c response c f upstream and downstream migrants must he o p p o s i t e , the former a c t i v e l y mcving upstream. I t was suggested t h a t f r y m i g r a t i o n i s an i n n a t e behavior p a t t e r n , whether i t be upstream or downstream the process i s s i m i l a r , hence a c t i v e displacement. The process of downstream migration i s probably a combination of a c t i v e and passive displacement. As a r n o l d (1974) p o s t u l a t e s , f r y are most l i k e l y d i s p l a c e d downstream by modulated d r i f t , the d i r e c t i o n of c u r r e n t determining d i r e c t i o n 7 9 c f displacement when the f r y f i r s t emerge frcm the g r a v e l . However, s i n c e the g r e a t e s t m o r t a l i t y upon f r y at t h i s stage i s p r e d a t i o n , i t i s i n c o n c e i v a b l e t h a t f r y have no c c n t r c l over t h e i r movement. The f r y emerge a t low l i g h t i n t e n s i t i e s , when r i s k of predation i s s l i g h t . A s t a t e of p a r t i a l n i g h t b l i n d n e s s does occur, the f r y l o s e v i s u a l c o n t a c t with the stream bottom and are i n i t i a l l y swept downstream. Once i n the c u r r e n t the f r y undoubtedly can d e t e c t and c o n t r o l t h e i r movement. As the eyes f u l l y dark-adapt, f r y a c t i v e l y pursue a ccurse downstream; e n a b l i n g a r a p i d t r a n s i t through p r e d a t i o n zones. The emerged f r y e i t h e r reach the ' s e c u r i t y ' cf the l a k e i n one n i g h t , or e l s e , spread t h e i r downstream migration ever a number of evenings, spending d a y l i g h t hours congregated i n shaded h o l d i n g pools along stream banks, p r e f e r r i n g deep water or b u r i e d under cover (Hoar 1953, 1956, 1S58; McDonald 1960; Neave 1955). A f t e r the f r y have been exposed t c l i g h t , and e s p e c i a l l y upon lake e n t r y , the f r y abandon previous s c l i t a r y h a t i t s and form s c h o o l s (Hartman e t a l . 1962; Hoar 1956; McCart 1967; McDonald 1960). Als o , f o l l o w i n g l i g h t exposure they show l e s s cover response while swimming and feeding i n b r i g h t l y l i g h t e d areas (Hartman et a l . 1962; McCart 1967). C. S i g n i f i c a n c e of P r e d a t i o n Throughout the s h o r t time frcm emergence to the end of downstream movement, pr e d a t i o n i s the major source cf m o r t a l i t y (Hunter 1959; Neave 1953; R i c k e r 1941; Roos 1960), estimates ranging from 20 to 80%. Patterns of f r y behavior a s s o c i a t e d with 80 t h i s p e r i o d have apparently developed t c reduce the r i s k of p r e d a t i o n . Emergence i n t o a dark environment, r a p i d t r a n s i t downstream, and subsequent s c h o o l i n g behavior, a l l operate t o i n c r e a s e s u r v i v a l (Hartman et a l , 1962) and hence l i m i t predator-prey encounters. However, how do prey (sockeye f r y ) r e a c t i f encounter occurs, or i n e f f e c t , what i n f l u e n c e do predators have upon the downstream movement of the f r y ? Previous work (Ginetz 1972; Ginetz S l a r k i n 1976) showed thr e e i n t e r e s t i n g f e a t u r e s of prey r e a c t i o n to predator encounters. F i r s t , p r i o r exposure t o predators i n c r e a s e d f r y s u r v i v a l . Naive f r y migrating down a r t i f i c i a l stream channels s u f f e r e d g r e a t e r m o r t a l i t i e s compared to experienced f r y , those having p r e v i o u s l y i n t e r a c t e d with p r e d a t c r s . Secondly, the n i g h t l y downstream m i g r a t i o n p a t t e r n of naive and experienced f r y , i n the absence/presence or p r e d a t c r s v a r i e s . In the presence of p r e d a t o r s , naive f r y migrated downstream r a p i d l y ; yet without predators the m i g r a t i o n was spread out over the evening, and many more non-migrants r e s u l t e d . T h i s tended to i n d i c a t e t h a t naive f r y became aware i n a s h o r t time span of seme d i f f e r e n c e which was p o t e n t i a l l y dangerous. The m i g r a t i o n p a t t e r n s of naive and experienced f r y i n the presence of predators d i f f e r e d i n two r e s p e c t s : (1) the n a i v e f r y were somewhat slower i n m i g r a t i n g , and (2) naive f r y s u f f e r e d a g r e a t e r m o r t a l i t y . T h i s suggested t h a t the naive f r y , l a c k i n g p r evious experience with p r e d a t o r s , were more s u s c e p t i b l e to p r e d a t i o n . F i n a l l y , b e h a v i o r a l o b s e r v a t i o n s of naive and experienced f r y found the l a t t e r to form more compact s c h o o l s p r i c r to and i n response to a s t i m u l u s , ftlsc, experienced 81 i n d i v i d u a l s d i s p l a y much l e s s movement when s t i m u l a t e d ; naive f r y are more a c t i v e . Thus summarizing t h e i r (Ginetz 1972; Ginetz S l a r k i n 1976) r e s u l t s : (1) naive f r y become aware cf the presence of p r e d a t o r s , and respond by m i g r a t i n g downstream at a f a s t e r r a t e as compared to naive f r y i n the absence of p r e d a t o r s . (2) once naive f r y experience a predator system, the i n f o r m a t i o n gained i s somehow u t i l i z e d i n subsequent predator encounters. (3) i t appears t h a t the behavior p a t t e r n of naive f r y changes f o l l o w i n g s t i m u l a t i o n (eg. predator encounters, etc.) , hence f a c i l i t a t i n g g r e a t e r s u r v i v a l and s u c c e s s f u l downstream m i g r a t i o n . E. Migrants and Non-migrants Working with t h i s b a s e l i n e of r e s u l t s , experimental work covered i n t h i s paper continued an examinaticn of v a r i o u s aspects of f r y behavior. In p a r t i c u l a r , t hree g e n e r a l areas were covered: (1) an i n v e s t i g a t i o n of the b e h a v i o r a l composition of naive f r y , and, the e f f e c t of experience upon the f r y ; (2) f r y behavior response to v a r i o u s predators; and (3) the change i n f r y behavior upon emergence from the g r a v e l . P r e l i m i n a r y experiments (Section A) f u r t h e r supported the r e s u l t s of Ginetz S L a r k i n (1S76), and l e d t c the development of a r a t h e r i n t e r e s t i n g r e l a t i o n s h i p . The r e s u l t s presented w i t h i n , plus a re-examination of G i n e t z s * (1972) work, shewed a c o n s i s t e n t p a t t e r n emerging; that i s , the percent f r y m o r t a l i t y (ca. 10-30%) of naive f r y migrating down predator channels was approximately egual to the percent non-migrants ( i . e . f r y not 82 m i g r a t i n g downstream overnight) m i g r a t i n g i n the absence o f predators. From t h i s i t was s p e c u l a t e d t h a t the f r y eaten were ones which would be c a t e g o r i z e d as non-migrants i n p r e d a t o r - f r e e channels. To i n v e s t i g a t e t h i s r e l a t i o n s h i p , succeeding experiments (Section E) were designed t o examine the b e h a v i o r a l composition of naive f r y . I t was p o s t u l a t e d t h a t there are two general f r y t y p e s , f a s t and slow migrants. E e s u l t s showed a p o s i t i v e tendency f o r naive f r y to be c h a r a c t e r i z e d by these twc groups: f a s t migrants - those migrating downstream during the peak mi g r a t i o n hours, and, slow migrants - these not m i g r a t i n g downstream over n i g h t , (mean percentage = 24.3%). C o n s i s t e n c y o f f u r t h e r r e s u l t s , migration p a t t e r n s and percent migrants/non-migrants f o r both f a s t and slow migrants t e s t e d i n d i v i d u a l l y , f a v o r s the i n t e r p r e t a t i o n t h a t there i s a d i s t i n c t d i f f e r e n c e between these twc f r y types. Two g u e s t i o n s a r i s e , what i s the o r i g i n of t h i s d i f f e r e n c e , and, why are t h e r e two types emerging? T h e . o r i g i n may be e i t h e r : (a) g e n e t i c a l l y f i x e d , (b) e n v i r o n m e n t a l l y induced, or (c) an i n n a t e behavior which i s i n f l u e n c e d or d i r e c t e d by a v a r i e t y of environmental v a r i a b l e s . In t h i s case, environmental i n d u c t i o n i m p l i e s t h a t the f r y l a c k s i m i l a r b i o t i c and/or a b i o t i c s t i m u l i ; such as, experience i n l i g h t , i n t e r a c t i o n s with other f r y or p r e d a t o r s , e t c . . The e x i s t e n c e of these twc f r y types i s much mere d i f f i c u l t to i n t e r p r e t . F i r s t , from the noted r e l a t i o n s h i p between percent ncr-migrants and percent eaten, the slow migrants may be present i n numbers s u f f i c i e n t to s a t i a t e predators r e s i d i n g i n the 83 streams. Hence, a c e r t a i n small percentage cf any f r y emergence i s somehow more l i k e l y to be consumed by p r e d a t o r s . The behavior p a t t e r n s of these slow migrants may be g e n e t i c a l l y d i f f e r e n t , thus a t t r a c t i n g p r e d a t o r s . They may not fcrm d i s t i n c t , c ohesive s c h o o l s while migrating downstream, or they may maintain a c t i v e swimming, with e r r a t i c movements, when confronted by a predator. In c o n t r a s t , f a s t migrants may form s c h o o l s and remain motionless i n the presence of p r e d a t o r s ; s i m i l a r to behavior noted f o r experienced f r y (Ginetz 1972). T h i s d i f f e r e n c e , however, may r e s u l t from l a c k of s i m i l a r s t i m u l i . The m a j o r i t y of n a i v e f r y ( f a s t migrants) may have had s i m i l a r e xperiences, such as enough time i n a low l i g h t regime to form f r y - f r y a s s o c i a t i o n s ; hence may s c h c c l more e f f i c i e n t l y , whereas slow migrants may emerge much l a t e r i n the evening, not having the same o p p o r t u n i t y to i n t e r a c t with other f r y . Another p o s s i b i l i t y i s a simple p h y s i c a l c h a r a c t e r i s t i c which d i f f e r s between the f r y . For example, a c e r t a i n p r o p o r t i o n (slow migrants) may be s m a l l e r due to l e s s maternal y e l k , or poor i n c u b a t i o n c o n d i t i o n s . These f r y may net j o i n with l a r g e r f a s t migrants; an o b s e r v a t i o n noted c f s c h o o l i n g sockeye f r y i n l a b o r a t o r y stream tanks. A second p o s s i b i l i t y t o account f o r the presence of two f r y types i s r e l a t e d to the phencmenon of upstream sockeye f r y mi g r a t i o n s (McCart 1967; Byrne 1S71; E a l e i g h 1967, 1971; Kelso 1S72; Erannon 1967, 1S72; Arnold 1974; the l a t t e r two f o r a comprehensive review). I t i s s p e c u l a t e d that the slew migrants i n the study are s i m i l a r t o upstream migrants; while f a s t migrants are r e a c t i n g as normal downstream migrating f r y . 84 Erannon (1972) concluded t h a t mechanisms c o n t r o l l i n g f r y migrations are g e n e t i c a l l y rased, yet i n f l u e n c e d by both b i o t i c and a b i o t i c s t i m u l i , (e.g. o l f a c t i o n , water temperature and ambient l i g h t ) . Hence p o s s i b l y w i t h i n a spawning p o p u l a t i o n of normally downstream migrants, a c e r t a i n p r o p o r t i o n may be g e n e t i c a l l y maintained as upstream migrants. T h e i r purpose c o u l d be manyfold, being maintained p r i n c i p a l l y as a ' s a f e t y f e a t u r e * c o u n t e r i n g unusual environmental c o n d i t i o n s . I f r a r e c o n d i t i o n s occur, such as poor t i m i n g between f r y emergence and lake plankton p r o d u c t i v i t y , f r y which maintain themselves wi t h i n the stream f o r a l c n g e r p e r i c d , then e v e n t u a l l y head downstream as a l a s t r e s o r t , may be most s u c c e s s f u l . Observations (McCart 1967) on the behavior cf upstream migrants i n d i c a t e d t h a t upstream movement was c o n f i n e d t o d a y l i g h t , with the f r y being much l a r g e r . G e n e r a l l y , the movement p a t t e r n was i n i t i a l l y downstream, ho l d i n g f o r a pe r i o d i n pools, then followed by an e v e n t u a l r e t u r n upstream. Therefore these slow migrants may i n f a c t be upstream migrants which have emerged the previous n i g h t and are i n i t i a l l y e i t h e r slowly mcving downstream, or maintaining t h e i r p o s i t i o n i n the stream, p r i o r to upstream movement, k second p o s s i b i l i t y i s t h a t those f r y r e s u l t from wandering of stock which normally produce upstream migrants i n the Babine system (McCart 1967). McCart (1S67) a l s o noted the e x i s t e n c e of an i n t e r m e d i a t e type c f f r y behavior i n which f r y t e m p o r a r i l y held along the stream edge but e v e n t u a l l y move downstream. Obviously the problem i s complex and f u r t h e r experiments 85 are needed to determine i f these f r y are, i f not an experimental a r t i f a c t , a common occurrence each year, and present i n other spawning s t o c k s . I f a l l emerging f r y are found to c o n t a i n both f a s t and slow migrants, these s p e c u l a t i o n s need then be t e s t e d . Observations should show i f these two types are b e h a v i c r a l l y d i f f e r e n t ( schooling behavior, r e a c t i o n t c pr e d a t o r s , r h e o t a c t i c response, e t c . ) , or p o s s i b l y p h y s i c a l l y d i f f e r e n t ( s i z e , yelk a b s o r p t i o n , e t c . ) . I t should a l s o be p o s s i b l e to compare s u r v i v a l , thus t e s t i n g the f i r s t s p e c u l a t i o n r e g a r d i n g d i f f e r e n t i a l p r e d a t i o n , !• ?he E f f e c t of Experience V u l n e r a b i l i t y t o pr e d a t i o n may be the r e s u l t cf two d i f f e r e n c e s i n the prey p o p u l a t i o n . F i r s t , i n t r i n s i c d i f f e r e n c e s , e i t h e r b e h a v i o r a l or s t r u c t u r a l , may enable predators to d i f f e r e n t i a l l y s e l e c t . , Predators may a c t i v e l y s e l e c t f o r the 'abnormal' within a group; or, s e l e c t on a r e l a t i v e b a s i s , comparing one t c another (Earns 1967). Stud i e s of hatchery versus n a t u r a l produced f r y (Earns 1967; y i b e r t 1958) have shown d i f f e r e n t i a l s u r v i v a l due to i n t r i n s i c d i f f e r e n c e s . Secondly, e a r l y experiences t h a t modify innate behavior p a t t e r n s may be r e s p o n s i b l e f o r d i f f e r e n c e s i n v u l n e r a b i l i t y . The behavior of newly hatched f r y w i l l c o n s i s t of a l i m i t e d number of i n n a t e , stereotyped p a t t e r n s (Hoar 1958). F o l l o w i n g emergence, responses to i n t e r n a l and e x t e r n a l s t i m u l i w i l l r a p i d l y i n c r e a s e the r e p e r t o i r e of these p a t t e r n s ; thus a d a p t i v e l y t r a n s f o r m i n g f r y behavior. The sooner f r y acquire 86 n o n - i n s t i n c t i v e b e h a v i o r a l responses to e x t e r n a l s t i m u l i , the b e t t e r are t h e i r chances f o r s u r v i v a l (Welty 1934). The importance of e a r l y experiences i n determining s u r v i v a l i s supported by experimental evidence. Dealing with predator-prey encounters as a l e a r n i n g e x p e r i e n c e , the s u c c e s s f u l escape of a prey w i l l depend to a l a r g e extent upon the time taken t o reco g n i z e the source of danger, and the r a p i d formation of a defens i v e response (Thompson 1966). A v a i l a b l e experimental evidence ( G i r s a 1962; Thompson 1966; G i n e t z 1972; Eatten 1977) supports t h i s s u p p o s i t i o n t h a t experience i n c r e a s e s s u r v i v a l with subseguent predator encounters. Those i n d i v i d u a l s t h a t s u r v i v e d an i n i t i a l encounter were t h e o r e t i c a l l y able t o recognize a dangerous s i t u a t i o n and take e v a s i v e a c t i o n by developing some form of c o n d i t i o n e d predator avcidance b e h a v i c r . Patten (1977) a l s o found t h a t combining naive with experienced f r y , the s u r v i v a l r a t e was not s i g n i f i c a n t l y d i f f e r e n t from experienced f r y . T h i s i m p l i e d t h a t naive f r y could i m i t a t e , or l e a r n from experienced f r y i n a very s h o r t time p e r i o d . In l e a d e r s h i p experiments, Welty (1934) l i k e w i s e found t h a t t r a i n e d f i s h c o uld i n f l u e n c e the behavior of untrained f i s h . As mentioned, G i n e t z (1972), i n a s i m i l a r experimental design found: (1) those f r y having s u r v i v e d an i n i t i a l p redator-prey encounter ( i . e . migrated down an a r t i f i c i a l stream channel c o n t a i n i n g p r e d a t o r s ) , had h i g h e r s u r v i v a l rate during subseguent encounters; and (2) i n predator channels, experienced f r y migrated downstream s l i g h t l y f a s t e r compared to naive f r y . I t was suggested t h a t the experience cf pr e d a t c r encounter w i t h i n the trough was s u f f i c i e n t to modify the behavior o f naive 87 f r y ; aquarium o b s e r v a t i o n s s u b s t a n t i a t e d b e h a v i o r a l d i f f e r e n c e s between these twc f r y types. Part of the experimental r e s e a r c h covered i n the r e s u l t s was designed t o f u r t h e r examine the e f f e c t of predator-prey encounters, e s p e c i a l l y f o l l o w i n g the d i v i s i o n of f r y i n t o f a s t and slow migrants. The r e s u l t s of an i n i t i a l experiment only s l i g h t l y d i f f e r e n t i a t e d between f a s t and experienced migrants; however both were s i g n i f i c a n t l y d i f f e r e n t frcm slow migrants. I t was spe c u l a t e d t h a t e i t h e r the experience was net s u f f i c i e n t t o r e g i s t e r any d i f f e r e n c e , or, f a s t migrants had obtained some form of experience p r i o r t o or durin g the experimental procedure. A second experiment, compounding f r y type with a l i g h t treatment, on the whole showed expected trends f o r experienced f r y . These r e s u l t s were more f u l l y d i s c u s s e d i n the a p p r o p r i a t e s e c t i o n . C i t e d r e f e r e n c e s and t i e f o r e g o i n g experiments imply t h a t predator encounters were s u f f i c i e n t t c modify innate f r y behavior p a t t e r n s . How the naive f r y p e r c e i v e a p o t e n t i a l l y dangerous s i t u a t i o n i s d i f f i c u l t t o a s c e r t a i n . A c t u a l predator a t t a c k , v i s u a l c o n t a c t , or response of surrounding f r y to a predator may be s u f f i c i e n t to r e i n f o r c e or s t i m u l a t e an in n a t e predator avoidance behavior. Two behavior p a t t e r n s have been suggested as predator avoidance responses. In l a b s t u d i e s , Ginetz (1972) found t h a t experienced f r y schooled p r i o r t c and i n response to a s t i m u l u s ; with the s c h c c l s g e n e r a l l y being compact and c o n t a i n i n g a l l the f r y . T h i s was i n c o n t r a s t t o nai v e f r y which formed loose aggregations seldom c o n t a i n i n g a l l the f r y . Bowen (1931) and Williams (1964) suggested t h a t t h i s 88 aggregating behavior reduced the r i s k t o p r e d a t i o n ; any f i s h not w i t h i n the c o n f i n e s , or cn the p e r i p h e r y of the s c h o c l were su b j e c t t c g r e a t e r p r e d a t i o n pressures ( M a n t e i f e l * & Eadakov 1S61; M i l i n s k i 1977aSb). Pe r s o n a l lab o b s e r v a t i o n s v e r i f i e d t h a t t r o u t predators seldom attacked a s c h c c l cf sockeye f r y , i n v a r i a b l y they pursued an i n d i v i d u a l not maintaining i t s e l f within the group. Secondly, experienced f r y remained motionless w i t h i n a s c h o o l d u r i n g a s t i m u l u s , whereas naive f r y upon s t i m u l a t i o n were more a c t i v e and appeared 'bewildered 1 (Ginetz S L a r k i n 1S76) . Ware (1971) found t h a t t r c u t were able t o r e c o g n i z e mcving prey with a g r e a t e r success than s t a t i o n a r y t a r g e t s ; thus remaining s t i l l seems to be a more e f f i c i e n t a n t i - p r e d a t o r d e v i c e . In determining what k i n d of experience e l i c i t s a behavior m o d i f i c a t i o n i n the f r y , i t was of i n t e r e s t t c d e t e c t i f f r y respond d i f f e r e n t i a l l y to v a r i o u s p r e d a t o r s . Within the f i e l d system under study numerous s p e c i e s c o h a b i t , the two most numerous being rainbow t r o u t and mountain w h i t e f i s h , ( D i l l 1S69). T h e o r e t i c a l l y t r o u t are g e n e r a l l y nidwater to s u r f a c e f e e d e r s , whereas w h i t e f i s h are bottcm f e e d e r s , being m o r p h o l o g i c a l l y i l l - a d a p t e d f o r f i s h p r e d a t i o n (McCart 1S67). Thus i t was expected t h a t the f r y would respond most v i g o r o u s l y to t r o u t encounters. T h i s was p a r t i a l l y v e r i f i e d i n one s e t o f experiments, however the remainder f a i l e d t c shew any c o n c l u s i v e d i f f e r e n c e s . I t was surmised t h a t w i t h i n the c o n f i n e s of the experimental troughs, any encounter with a l a r g e f i s h was s u f f i c i e n t t o c o n d i t i o n a predator avoidance response. In n a t u r a l streams, the encounter p r o b a b i l i t y w i l l be dependent 89 upon the s p a t i a l and temporal d i s t r i b u t i o n cf both the f r y and predators. !• ?he S i g n i f i c a n c e of Schooling Ginetz (1972) found t h a t predator encounters alone were not necessary f o r modifying f r y behavior. Enumerated f r y d i s p l a y e d b e h a v i o r a l responses s i m i l a r to experienced f r y . An experiment designed to determine what f e a t u r e of the enumeration procedure was r e s p o n s i b l e f o r s t i m u l a t i n g an experience showed t h a t s u b j e c t i n g the f r y to a s h o r t time p e r i o d i n the l i g h t was s u f f i c i e n t . Lab experiments attempted t o determine the importance of l i g h t i n the e a r l y behavior of these sockeye f r y . Three f e a t u r e s were e v i d e n t . F i r s t , with an i n i t i a l s u b j e c t i o n t o l i g h t , much time i s spent i n nervous a c t i v i t y forming f r y a s s o c i a t i o n s and e x p l o r i n g the new environment. Secondly, as they spend a longer p e r i o d i n the l i g h t , the f r y become more c o n f i d e n t with t h e i r surroundings and a s s o c i a t i o n s . T h i s i s r e f l e c t e d by a decrease i n random swimming by i n d i v i d u a l s , with the subseguent development of s c h o o l i n g b e h a v i o r . F i n a l l y , as the f r y i n t e r a c t with a g r e a t e r number of i n d i v i d u a l s f o r a l c n g e r time p e r i o d , t h e i r confidence i n c r e a s e s with school development and s t r u c t u r e s t a b i l i z i n g , as measured by a decrease i n a c t i v i t y . Throughout t h i s work, i t has been assumed t h a t the b e h a v i o r a l response enhancing f r y s u r v i v a l i s s c h c c l i n g . Although s c h o o l i n g serves many f u r c t i o n s i n many s p e c i e s , i t has 90 been suggested t h a t the prime adaptive f e a t u r e i s a defense r e a c t i o n f o r predator avoidance and d e t e c t i o n ( N e i l l & C u l l e n 1974; Eadakov 1973; Erock & E i f f e n b u r g h 1960; P i t c h e r 1S73). E a s i c a l l y , s c h o o l s or aggregations l e s s e n the chance of predator-prey encounters. Once d e t e c t e d , the s t r u c t u r e and movement of the s c h o o l w i l l produce a •confusion e f f e c t ' , which reduces the p r o b a b i l i t y of s u c c e s s f u l a t t a c k and capture. Schooling behavior develops, g r a d u a l l y ever a p e r i o d cf time (Shaw 1960). The newly emerged f r y must l e a r n to i n t e r a c t and a a s s o c i a t e with other i n d i v i d u a l s . Hoar (1956) found t h a t migrating pink f r y were not schooled u n t i l a f t e r a short exposure to l i g h t . F o l l o w i n g emergence, but p r i o r to an i n i t i a l s c h c o l i n g experience, sockeye f r y bury themselves i n the g r a v e l during the day. Yet once the f r y have a s s o c i a t e d i n a l o o s e aggregation, they remained i n t h e water column moving as a group, (McCart 1967). V i s i o n i s c o n s i d e r e d to be the prime sensory s t i m u l u s i n f i s h - t o - f i s h a t t r a c t i o n , (Breder 1951, 1967; Morrow 1948; Shaw 1960) ; yet not the only r e c e p t o r o p e r a t i n g i n the maintenance of the s c h o o l (John 1964; Keenleyside 1955; Moulton 1960; Eadakov 1S73). Thus the prime m o t i v a t i o n a l f o r c e s i n v o l v e d i n the development of s c h o o l i n g i n these f r y , i s f i r s t , some amount of time spent i n t e r a c t i n g with each other; secondly, a minimum l i g h t i n t e n s i t y e n a b l i n g i n t e r a c t i o n and f i n e tuning of b e h a v i o r a l responses; and f i n a l l y , the innate p r o p e n s i t y f o r the development of s c h o o l i n g . E x t r a p o l a t i n g to the streambeds, as f r y cemmence emergence, they move from the dark, deep i n t e r s t i c e s of the g r a v e l to the 1 91 s u r f a c e l a y e r s , where ambient l i g h t p e n e t r a t e s to some degree (Heard 1964).. In the a v a i l a b l e l i g h t , f r y - t c - f r y a s s o c i a t i o n s are formed, f a c i l i t a t i n g i n i t i a l s c h o o l i n g behavior. 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The adaptive s i g n i f i c a n c e of s c h o o l i n g behaviour i n f i s h e s . Russian Bev. E i c l . 50:338-345. McCART, P. 1967. Behaviour and ecology of sockeye salmon f r y i n the Babine R i v e r . J . F i s h . Res. Board Can. 24:375-428. MCDONALD, J . 1960. The behaviour of P a c i f i c salmon f r y during t h e i r downstream migrat i o n t c freshwater and s a l t w a t e r nursery areas. J , F i s h . Res. Board Can. 17:655-676. fclLINSKI, M. 1977a. Experiments on the s e l e c t i o n by predators a g a i n s t s p a t i a l o d d i t y of t h e i r prey. Z. T i e r p s y c h c l . 43:311-325. KILOS KI, M.' 1977b. Do a l l members of a swarm s u f f e r the same predation? Z. T i e r p s y c h o l . 45:389-413. MOEICW, J . E. 1948. Sc h o o l i n g behavior i n f i s h e s . Quart; Eev. B i c l . 23:27-38. MCULTON, J . M. 1960. Swimming sounds and the s c h o o l i n g o f f i s h e s . B i c l . „ B u l l . 119:2.10-223. NEAVE, F. 1953. P r i n c i p l e s a f f e c t i n g the s i z e of pink and chum salmon p o p u l a t i o n s i n E r i t i s h Columbia._J. F i s h . Bes. Board Can, 9:450-491. NEAVE, F. 1955; Notes on the seaward m i g r a t i o n of pink and chum salmon f r y . J . F i s h . Res. Board Can. 12:369-374. NEILL, S. E. St. J . & J . M. CULLEN. 1974..Experiments on whether s c h o o l i n g hy t h e i r prey a f f e c t s the hunting behaviour of cephalopods and f i s h predators. J . Z o o l . , Lond. 172:549-569. EATTEN, E. G.' 1977. Body s i z e and learned avoidance as f a c t o r s a f f e c t i n g p r e d a t i o n on coho salmon, Onccrhynchus k i s u t c h , f r y by t o r r e n t s c u l p i n , Cottus rhotheus. F i s h . B u l l . , 0. S. 75:457-459. 95 FITCHEE, T. J . 1973. The t h r e e - d i m e n s i o n a l s t r u c t u r e of sc h o o l s i n the minnow, Phoxinus phoxinus (L.) . Anim.. Eehav. 21:673-686. FBITCHAED, A. L. 1944. P h y s i c a l c h a r a c t e r i s t i c s and behavior of pick salmon f r y at McClintcn Creek, B.C. J . F i s h . Ees. Board Can. 6:217-227. EAEAKOV, D. V. 1973. Schooling i n the ecology of f i s h . , Engl. T r a n s l . , I s r a e l Program S c i . T r a n s l . P u t l . , John Wiley and Sons, N. Y. , 173p. BAIEIGH, E. F. 1967. Genetic c o n t r o l i n the lakeward m i g r a t i o n s of sockeye salmcn (Oncorhynchus nerka) f r y . J . F i s h . Ees. Eoard Can. 24:2613-2622. EALEIGH, E. F. 1971. Innate c o n t r o l of migrat i o n s of salmcn and t r o u t f r y from n a t a l g r a v e l s t o r e a r i n g areas. Ecology 52:291-297. EICKEE, W. E. 1941. The consumption of young sockeye f r y by predaceous f i s h . J . F i s h . Ees. Board Can. 5:293-313. EOCS, J . F. 1960. Pred a t i o n c f young echo salmon cn sockeye salmon f r y at C h i g n i k , A l a s k a . Trans. Am. F i s h . . Soc. 89:377-379. SHAW, E. 1960. The development of s c h o o l i n g behavior i n f i s h e s . P h y s i o l . Zool. 33:79-86. STEVEN, D, M. 1959. Studies on the s h o a l i n g behavior of f i s h e s . I. Besponses of two s p e c i e s t o changes cf i l l u m i n a t i o n and to o l f a c t o r y s t i m u l i . J . Exp, B i o l , 36:261-280. THCKPSON, E. B. 1966. E f f e c t s of predator avoidance c o n d i t i o n i n g on the p o s t - r e l e a s e s u r v i v a l r a t e of a r t i f i c i a l l y propagated salmon. Ph.p. T h e s i s , Univ. Washington, S e a t t l e , Wash., 155p. VIBEET, E. 1958. C r i t e r e s et t e s t s de r u s t i c a t e chez l e s t r u i t e s et l e s saumons. Verb, i n t . Ver, Limnol, 13:758-764. WAEE, D.. M. 1971. The predatory behaviour of rainbow t r o u t (Salmo g a i r d n e r i ) . Ph.D. T h e s i s , Univ. B r i t i s h Columbia, Vancouver, B.C., 156p. WE1TY, J. C. 1934. Experiments i n group behavior i n f i s h e s . P h y s i o l . Z o o l . 7:85-128. WILLIAMS, G. Cm 1964.„Measurement o f c o n s o c i a t i c n among f i s h e s and comments on the e v o l u t i o n of s c h o o l i n g . Publ. Mus. Michigan State Univ., B i o l . . Ser. 2:349-384. APPENDICES APPENDIX I: Three-way a n a l y s i s of variance cn a r c s i n e transformed values of percent migrants per sampling time p e r i o d . A n a l y s i s compared d i f f e r e n c e s i n m i g r a t i o n p a t t e r n f o r naive f r y i n a r t i f i c i a l stream channels with and without p r e d a t o r s . Source of V a r i a t i o n 1 DF | SS I MS I F F a c t o r s : j | | Time p e r i o d s j 5 I 3967.82 | 793,.56 I 13.81 ** Days I 2 I 76.65 | 38.32 I 0.67 Predators +/- I 2 1 13.76 | 6.88 | 0. 12 I n t e r a c t i o n s : | | | | Time per. x Days | 10 | 603.49 | 60.35 | 1.05 Time per. x Preds, | 10 | 1757.80 | 175.78 | 3.06 * Days x Preds.. I 4 I 24.1 8 | 6,05 | 0. 11 E r r o r 1 20 | 1149.21 I 57.46 T o t a l I 53 | 7592 . 9 1 ! ! ; * = s i g n i f i c a n t a t 5% l e v e l ** = s i g n i f i c a n t at 15? l e v e l Time pe r i o d s = sampling i n t e r v a l s (0.5 hour periods) Days = experiment r e p l i c a t e s Predators +/- = stream channels with (rainbow, whitefish) and without predators 97 AEgENDix I I : Four-way a n a l y s i s of vari a n c e on a r c s i n e transformed values of percent migrants per sampling time p e r i o d . A n a l y s i s compared d i f f e r e n c e s i n m i g r a t i o n p a t t e r n f o r v a r i o u s experienced f r y , from the two spawning channels, i n a r t i f i c i a l stream channels with and without p r e d a t o r s . Source of V a r i a t i o n 1 H--DF I SS | MS I -4-F • * • ^  * ^ * E a c t o r s : | | I J Time p e r i o d s | 4 | 20457.58 | 5114. 39 | 87. 0 4 ** Experience | 4 39.02 | 9. 76 | 0. 17 Channels 1 1 | 59.95 | 59. 95 | 1. 02 Predators +/- I 2 228.04 | 114. 02 I 1. 94 I n t e r a c t i o n s : I | | | Time per. x Exper. i 16 | 1921.65 | 120. 10 | 2. 04 * Time per. x Chan. i - 4 | 545.41 | 136. 35 | 2. 32 Exper. x Chan, i 4 | 119.89 I 29. 97 | 0. 51 Time per. x Preds. j 8 j 730.23 | 91. 28 | 1. 55 Exper. x Preds. i 8 | 104.93 | 13. 12 | 0. 22 Chan, x Preds. i 2 | 199.44 | 99. 72 | 1. 70 E r r o r i 96 ) 5640.67 | 58. 76 I T o t a l ! 149 ! 30046.81 | I I * = s i g n i f i c a n t at 5% l e v e l ** = s i g n i f i c a n t at 1% l e v e l Time p e r i o d s = sampling i n t e r v a l s (0.5 hour periods) Experiences = f r y t h a t are i n e x p e r i e n c e d , enumerated, shocked, and experienced to predators Channels = Spawning Channels No. 1 and 2 Predators +/- = stream channels with (rainbow, w h i t e f i s h ) and without predators 98 APPENDIX I I I : Three-way a n a l y s i s of variance on a r c s i n e transformed values of percent migrants, non-migrants and eaten. A n a l y s i s compared d i f f e r e n c e s i n these values f o r var i o u s experienced f r y , from the two spawning channels, i n a r t i f i c i a l stream channels with and without predators. F a c t o r s as d e s c r i b e d i n Appendix I I . (a) % MIGSftNTS Source of V a r i a t i o n 1 DF | SS 1 MS I F I Experience | 4 1 365.48 | 91. 37 | 2. 42 Channels | 1 I 42.48 | 42. 48 | 1. 12 Predators v - | 2 I 1096,55 | 548. 28 | 14. 49 ** | Exper. x Chans. | 4 I 248.41 | 62. 10 | 1. 64 Exper. x Preds, | 8 I 4 00,90 | 50. 11 I 1. 33 Chans, x Preds. | 2 I 1002.58 | 501. 29 | 13. 25 ** | E r r o r 1 8 I 302.67 37. 83 | T o t a l ! 29 | 3459.07 ! I — — — 1 — — ^ 1 1 — - — — 1 (b) % NCN-MIGB BNTS r r 1 1 * T T ; 1 Source of V a r i a t i o n 1 I DF | • SS i MS | F I i Experience — r - —-+ 4 1 109.43 | 27.36 | 0.44 1 Channels | 1 | 4.40 | 4.40 | 0.07 Predators +/- | 2 I 2578. 04 | 1289.02 | 20.61 ** | Exper. x Chans. | 4 I 29.59 | 7.40 | 0. 12 Exper. x Preds. | 8 I 603.79 | 75.47 | 1.21 Chans, x Preds. | 2 I 163.47 | 81.73 | 1.31 E r r o r 8 I 500128 | 62.54 I T o t a l ! 29 | 3988.99 | [ (C) % EATEN r •• T 1 1 T — r 1 | Source of V a r i a t i o n | DF | SS | MS | F I I „ . + + , _ + 4 — A Experience 1 ^ 1 215.63 | 53.91 | 1.09 Channels I 1 I 423.84 | 423,84 | 8.59 * Predators */- I 1 i 946,28 | 946.28 | 19.17 ** Exper. x Chans. I 4 210.76 | 52.69 j 1.07 Exper. x Preds. I 4 I 252.06 i 63,01 | 1.28 Chans, x Ereds. I 1 12.09 | 12.09 | 0.25 E r r o r I " I 197.44 | 49.36 T o t a l I 19 2258.10 | t I I. , I L _ _ t J 'APPENDIX IV: Two-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants per sampling time p e r i o d . A n a l y s i s compared d i f f e r e n c e s i n m i g r a t i o n p a t t e r n f o r var i o u s experienced f r y . , i r -I DF | " I " I Source of V a r i a t i o n SS MS F a c t o r s : Experience Time periods I n t e r a c t i o n E r r o r T o t a l 4 6 24 35 I 70.64 2516.03 1673.56 1183.24 6S | 5443 I ,46 17.66 419.33 69.73 33.81 0.52 12.40 ** 2.06 * l J 1 J L - . , . — * = s i g n i f i c a n t at 5% l e v e l ** = s i g n i f i c a n t at 1% l e v e l E xperiences = as described i n Table IV Time p e r i o d s = sampling i n t e r v a l s (0.5 hour periods) 100 APPENDIX V: Three-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants per time p e r i o d . A n a l y s i s examined migrat i o n p a t t e r n s of v a r i o u s f r y types migrating through a r t i f i c i a l stream channels with and without p r e d a t o r s . r - — T 1 "i T • 1 | Source of V a r i a t i o n | DF | SS' | MS | F I F a c t o r s : I I I Time p e r i o d s | 6 1 4 2 3 3 4 . 8 9 | 7 0 5 5 . 8 1 | 1 1 6 . 9 1 ** Fry type | 2 1 1 7 0 . 5 5 | 8 5 . 2 7 | 1 , 4 1 Predators +/- | 3 1 2 0 5 . 4 4 | 6 8 . 4 9 | 1 . 1 3 I n t e r a c t i o n s : | j j j Time per. x Fry | 1 2 | 3 7 0 4 . 4 7 | 3 0 8 . 7 1 | 5 . 1 2 ** Time per, x Preds, | 1 8 | 3 3 6 1 . 7 9 | 1 8 6 . 7 7 | 3 . 1 0 ** Fry x Preds. j 6 i 9 U 7 2 | 1 5 . 2 9 | 0 . 2 5 E r r o r I 2 5 2 | 1 4 0 0 1 . 5 7 | 6 0 . 3 5 | T o t a l | 2 7 9 | 6 3 8 7 0 . 4 2 | I ** = s i g n i f i c a n t at ^% l e v e l Time p e r i o d s = sampling i n t e r v a l s ( 0 . 5 hour periods) Fry type = f a s t migrants, slow migrants and experienced Predators +/- = stream channels with (rainbow, w h i t e f i s h , r a i n r o w / w h i t e f i s h combination) and without pr e d a t o r s APPENDIX VI: Two-way a n a l y s i s of v a r i a n c e cn a r c s i n e transformed values of percent migrants per sampling p e r i o d ; examining e f f e c t c f predators on m i g r a t i o n p a t t e r n of the three f r y types. (a) FAST MIGRANTS: r " T 1 — — •* l T ' 1 | Source of V a r i a t i o n | DF \ SS | MS | F I t — ' — — - + * — - t - — ^ Time p e r i o d s Predators +/-Time per..x Preds. F r r o r T o t a l 6 3 18 €3 90 17147.06 | 2857.84 119.31 | 39.77 639.66 | 4367.67 | I 22273.70 | 35.54 69.33 41.22 0.5 7 0.5 1 * (jb) SLOW MIGEANTS: I Source of V a r i a t i o n j DF j SS MS Time p e r i o d s Predators +/-Time per. x Preds. F r r o r T o t a l 6 | 11412.38 | 1902.06 3 I 18 | 7 7 r I 55,. 5 8 | 1394.86 | 4633.04 | I 18,53 77.49 60. 17 104 | 174S5.87 | •1.6 1 0.3 1 1.29 (£.) EXPERIENCED: Source of V a r i a t i o n | DF | SS | MS I F I Time periods | 6 I 17479.91 | 2913.32 | 56.51 * I Predators +/- | 3 I 122.27 | 40.76 | 0.79 Time per. x Preds. | 18 | 3441.01 | 191.17 | 3.7 1 * | F r r o r | 56 | 2887.11 I 51.56 T o t a l | 83 | 23930.30 | ] . . j__ L . * = s i g n i f i c a n t at 5% l e v e l 102 SPPENDIX VII; Two-way a n a l y s i s of vari a n c e on a r c s i n e transformed values of percent migrants per sampling time p e r i o d ; examining the response of each f r y type w i t h i n the var i o u s predator regimes. (a) EAINEOW TJ3CDT r-— T T' | Source of V a r i a t i o n | DF | SS MS Time periods Fry type Time per. x Fry E r r o r T o t a l I 6 I 2 I 12 | I 2^ | | 12690.67 | 104.57 1C98.84 3541.09 | 62 | 17435.18 2115. 11 52.29 91.57 84.31 (t) WHITEFISH " T — — r -I DF | I - T -I i Source of V a r i a t i o n SS MS Time p e r i o d s Fry type Time per.,x Fry E r r o r I T o t a l i I 6 I • 2 | I 12 | I 63 | | 15564. 90 | 2594. 15 | 45.59 49.64 | 24.82 | 0.41 1577.94 | 3837.77 | | 83 | 21030.25 | 131.50 | 60.92 | I 2. 16 (C) RAINBOW TROOT/WHITEFISH r T ~ T ^ T -| Source of V a r i a t i o n I DF | SS | MS | I Time periods Fry type Time per. x F r y E r r o r I T o t a l I 97S7.78 j 1632.96 | 31,27 | 2 | 100. 96 | 50.48 | | 12 | 1978.70 | 164.89 | | 42 | 2193.21 | 52.22 | | 62 | 14070.65 I | 0.97 3. 16 (d) NO PREDATORS I I Source of V a r i a t i o n | DF | I +-,--+. | Time pe r i o d s | Fry type I Time per. x Fry I E r r o r | T o t a l I 6 | I 2 | I 12 | I 49 | SS | MS | F 7643.32 | 1273.89 | 26.95 7.10 | 3.55 | 0.08 1162.73 | 96.89 | 2.05 2315.75 | 47.26 | | 69 | 11128.90 | I * * 103 APPENDIX V I I I : Two-way a n a l y s i s of v a r i a n c e on a r c s i n e transformed values of percent migrants i n the f i r s t hour f o l l o w i n g the onset of the experiment. A n a l y s i s compared d i f f e r e n c e s i n these values f o r each f r y type i n a r t i f i c i a l stream channels with and without p r e d a t o r s . An a p o s t e r i o r i Duncan's New M u l t i p l e Eange Test compared d i f f e r e n c e s i n the means f o r each f a c t o r . Source of V a r i a t i o n | DF I SS Predators */- —H 1 3 | 2279.34 Fry type 1 2 | 3505.17 Preds. x Fry type 1 6 | 1534.76 E r r o r | 28 | 7158.70 T o t a l | 39 | 15477.96 'T-I MS 1093.1 1 1752.58 255.79 255.67 I 4.28 * 6.86 * 1.00 * = s i g n i f i c a n t at 5% l e v e l Predators +/- = stream channels with (rainbow, w h i t e f i s h , r a i n b o w / w h i t e f i s h combination) and without predators Fry type = f a s t migrants, slow migrants and experienced D.N.M.E.T. (a) PREDATOES +/-: Bain, White. Ea,/Wh. No pred. 73.87 70.22 67.23 50. 15 N.S, (b) FEY TYPE: Fast migs. Experienced Slow migs, 72.79 72.39 52.27 N.S. N.S. = mean values not s i g n i f i c a n t l y d i f f e r e n t 104 APPENDIX IX: Two-way a n a l y s i s of va r i a n c e cn a r c s i n e transformed v a l u e s of percent migrants, non-migrants and l o s t or eaten. A n a l y s i s compared d i f f e r e n c e s i n these values f o r the f r y t y p es i n a r t i f i c i a l stream channels with and without predators. (a) J MIGEANTS: | Source of V a r i a t i o n I Fry type Predators +/-Fry type x Preds. E r r o r | T o t a l DF | SS | MS | F 2 I _^  I 764.86 | 382.43 | 4. 81 3 I 1019.29 | 339.77 | 4. 27 6 I 660.33 | 110.05 | 1. 38 28 | 2226.15 | 7S.51 I 39 I 4670.63 1 j I -I * I I I (t) % NON-MIGEANTS : -T ' — T - ' T «• | SS | MS | F | Source of V a r i a t i o n H | Fry type | Predators +/-| Fry type x Preds, I E r r o r | T o t a l | DF + 2 3 6 28 923.57 1801.44 317.94 2530.66 39 | 5573,61 461.79 6C0.48 52.99 90,38 5. 11 6.64 0. 59 H <C) i LOST or EATEN | Source of V a r i a t i o n | DF f +  SS | MS ( F | 2 3 6 28 39 I Fry type | Predators +/-J Fry type x Preds. I E r r o r J T o t a l l P L - — _ - ^ J , - - J . . 28.88 328.29 357.12 S95.02 I 14.44 109.43 59.52 35.54 1709,31 | 0.41 3.08 1.68 * = s i g n i f i c a n t a t 5$ l e v e l ** = s i g n i f i c a n t at 1$ l e v e l Fry type = f a s t migrants, slow migrants, and experienced Predators +/- = stream channels with (rainbow, w h i t e f i s h , r a i n b o w / w h i t e f i s h combination) and without predators 105 APPENDIX X: Four-way a n a l y s i s of v a r i a n c e cn a r c s i n e transformed values of percent migrants per sampling time p e r i o d s . A n a l y s i s compared d i f f e r e n c e s i n m i g r a t i o n p a t t e r n f o r the t h r e e f r y types, s u b j e c t e d t o t h r e e l i g h t c o n d i t i o n s , i n a r t i f i c i a l stream channels with and without p r e d a t o r s . r 1 r " T T - 1 | Source of V a r i a t i o n | DF | SS J MS | F 1 y _ ,. ,_4 + + ^ F a c t o r s : Time pe r i o d s 5 1 14519.55 | 2903.91 | 49.4 1 ** Fry types 1 2 | 51.56 | 25.78 | 0.44 Hours l i g h t 1 2 32.72 | 16.36 | 0.28 Predators +/- 1 1 I . 112.85 | 112.85 | 1.92 I n t e r a c t i o n s : Time per. x F r y 10 | 1307.68 | 130.77 | 2.2 2 * Time per. x L i g h t I 10 j 879.62 | 87.96 | 1.50 Fry type x L i g h t I 4' 35. 85 | 8.96 | 0.15 Time per. x Preds. 5 | 2293.28 | 458.66 | 7.8 1 ** Fry type x Preds. 2 8.88 | 4.44 | 0.08 L i g h t x Preds. I 2 | 85^ 53 | 42.76 | 0.73 E r r o r 64 | 3760.91 | 58.76 | T o t a l 107 | 23088.42 | L , . L^. 1 „ L — L , I * = s i g n i f i c a n t at 5% l e v e l ** = s i g n i f i c a n t at 1% l e v e l Time p e r i o d s = sampling i n t e r v a l s (0.5 hour periods) Fry type = f a s t migrants, slow migrants.and experienced Hours l i g h t = number of hours f r y were subjected to l i g h t treatment (0, 6, 24 hours) Predators +/- = stream channels; with (rainbow, w h i t e f i s h , r a i n b o w / w h i t e f i s h combination) and without predators 106 APPENDIX XI: Three-way a n a l y s i s of variance on a r c s i n e transformed values of percent migrants i n f i r s t hour, migrants and non-migrants. A n a l y s i s compared d i f f e r e n c e s i n these values f o r the f r y types, subjected to three l i g h t c o n d i t i o n s , m i g rating through stream channels with and without p r e d a t o r s . (a) % MIGRANTS i n FIRST HOUR r ** T 1 1 T - T '• 1 I Source of V a r i a t i o n | DF | SS | MS | F I + +- 4 4 — Fry type 1 2 | 1050.64 | 525.32 | 3.75 Hours l i g h t 1 2 | 1305.99 i 652.99 | 4.66 Predators +/- 1 1 I 2300.68 | 2300.68 | 16.40 Fry type x L i g h t I a I 360.01 | SO.00 | 0.64 Fry type x Preds, I 2 | 760.95 | 380.47 | 2.71 L i g h t x Preds, I 2 | 651.27 | 325.63 | 2.32 E r r o r I *» I 561.07 | 140.27 T o t a l I 17 | 6990.61 i' (b) % MIGRANTS I Source of V a r i a t i o n Fry type Hours l i g h t P redators +/-Fry type x L i g h t Fry type x Preds. L i g h t x Preds. E r r o r T o t a l I DF | SS | MS I i F 2 | 77.78 | 38.89 0.63 2 | 424.30 | 212,15 j 3.45 1 | 1332.66 | 1232.66 | 21.66 4 | 241.46 | 60.36 j 0.98 2 | 215.51 | 1C7.76 | 1.75 2 | 147.72 | 73.86 | 1.20 4 | 246.07 | 61.52 17 | 2685.48 | j ** (C) 2 NON-MIGRANTS Source of V a r i a t i o n | DF i SS | MS | F H- 4- (._ Fry type I 2 | 37.55 | 18.77 | 0. 26 Hours l i g h t I 2 | 349.80 | 174.90 | 2.40 Predators +/- I 1 | 1550.50 | 1550 50 | 21.29 ** Fry type x L i g h t I 4 | 230.41 | 57.60 | 0.79 Fry type x Preds. I 2 | 285.31 | 142.66 | 1.96 L i g h t x Preds. I 2 | 220.87 | 110.43 | 1. 52 E r r o r I 4 | 291.25 | 72.81 | T o t a l | 17 | 2965.69 | j l . I I L L I 107 APPENDIX X I I : C o l l e c t i o n , f e r t i l i z a t i o n and i n c u b a t i o n procedures f o r salmon roe and f r y u t i l i z e d i n l a b o r a t o r y s t u d i e s . Approximately 20,000 eggs were s t r i p p e d from seven females, then d i v i d e d evenly i n t o f o u r water t i g h t p l a s t i c tags. C o n c u r r e n t l y , sperm from twelve males was d i v i d e d i n t o f o u r w a t e r t i g h t 4 oz g l a s s j a r s . For t r a n s p o r t , the c o n t a i n e r s were s e c u r e l y packed i n t o a coleman c o o l e r ; each c o n t a i n e r surrounded by i c e t c maintain low temperatures, and newspaper to absorb shock. F e r t i l i z a t i o n was conducted at the U n i v e r s i t y of B r i t i s h Columbia e i g h t hours a f t e r c o l l e c t i o n . I t c o n s i s t e d o f : (1) n i x i n g the eggs and sperm f o r 30 seconds; (2) b a t h i n g the eggs i n water f o r 3 minutes; and (3) then p l a c i n g the f e r t i l i z e d eggs i n t o f o u r Heath i n c u b a t i o n t r a y s . The eggs developed i n a v e r t i c a l flow i n c u b a t o r ; the water flow approximately 3,5 - 4.0 g a l / f f i n , and the water temperature decreasing from 12.5 ~ 4.0° C. A d e c h l c r i n a t o r reduced any c h l o r i n e i n the tap water, while a b a f f l e - s y s t e m p r o v i d e d adeguate oxygen. Oxygen was measured weekly, (HACH k i t ' and YSI Oxygen meter), and remained a t approximately 100% s a t u r a t i o n . P r i o r t c c i r c u l a t i n g through the i n c u b a t o r , a Cuno (G78B2) Kicrc-Kleam I I 5 micron f i l t e r e f f e c t i v e l y removed most p a r t i c l e s from the water. The f i l t e r s were changed p e r i o d i c a l l y , depending upon sediment b u i l d - u p . To prevent fungus i n f e c t i o n , a malachite green s o l u t i o n , (3 gms cf c r y s t a l d i s s o l v e d i n 1 l i t r e c f water; 80 ml/treatment f o r flow cf 3,5 - 4.0 gal/min) , was 108 added every second day u n t i l the eyes were well-pigmented. ft heating system was attached to augment the water temperature, but the flow was too great f o r i t be e f f e c t i v e . The temperature was recorded d a i l y and converted i n t o degree-days. F o l l o w i n g the eyed-stage (ca, 450 - 500 deg-days), dead eggs were removed every second day, and samples were p e r i o d i c a l l y examined f o r development stage. A f t e r 68 days, of i n c u b a t i o n (1280 deg-days), a l l eggs had hatched. Tc t e s t moving procedures and storage tanks, at 1400 deg-days, 300 a l e v i n s were moved to l a b o r a t o r y f a c i l i t i e s a t south campus, U n i v e r s i t y of B r i t i s h Columbia. Seven days l a t e r (1480 deg-days) a l l remaining a l e v i n s (95% s u r v i v a l frcm f e r t i l i z a t i o n to a l e v i n stage) were moved to south campus and s t o r e d i n twc darkened 227 l i t r e f i b e r g l a s s tubs. The water w i t h i n the tubs was c o n s t a n t l y r e c y c l e d and maintained at an approximate'temperature of 4 ± 1.5° C. The a l e v i n and f r y were fed using mechanical f e e d e r s on loan from Nanaimo B i o l o g i c a l S t a t i o n , F i s h C u l t u r e S e c t i o n . Oregon Moist Mash was a u t o m a t i c a l l y r e l e a s e d i n t o the storage tacks every hour f o r 30 seconds. , 

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