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Physiological response to challenge tests in six stocks of coho salmon Oncorhynchus kisutch McGeer, James C. 1990

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PHYSIOLOGICAL RESPONSE TO CHALLENGE TESTS IN SIX STOCKS OF COHO SALMON ONCORHYNCHUS KISUTCH. by JAMES C. MCGEER B.Sc. Ag., University of British Columbia, 1987 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF M. SC. in THE FACULTY OF GRADUATE STUDIES ANIMAL SCIENCE We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 1990 (c) James C. McGeer, 1990 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at The University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Animal Science The University of British Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date: December 14,1990 A b s t r a c t Coho salmon (Oncorhynchus kisutch) from s i x h a t c h e r i e s operated by the Canadian Department of F i s h e r i e s and Oceans Salmonid Enhancement P r o j e c t , were r e a r e d i n a common f a c i l i t y and then s u b j e c t e d t o a s e r i e s of s t a n d a r d i z e d c h a l l e n g e t e s t s . R e s u l t s suggest t h a t t h e r e are g e n e t i c a l l y based d i f f e r e n c e s i n the response t o s t r e s s f u l c h a l l e n g e s among s t o c k s of coho salmon from southern B r i t i s h Columbia. The c h a l l e n g e t e s t s were: s a l t w a t e r (30ppt); s a l t w a t e r and an i n c r e a s e i n temperature (30ppt and 4° C ) ; h i g h pH (9.4 and 10.0); low pH (3.55, 3.65, 3.75 and 4.1); thermal t o l e r a n c e (l°C/h); and h a n d l i n g (30s n e t t i n g ) . The measured parameters were plasma sodium and c h l o r i d e i o n c o n c e n t r a t i o n s f o r the s a l i n e and pH c h a l l e n g e s , time t o d y s f u n c t i o n i n the thermal t o l e r a n c e c h a l l e n g e and plasma glu c o s e c o n c e n t r a t i o n i n the h a n d l i n g c h a l l e n g e . No d i f f e r e n c e s among s t o c k s were found i n responses t o the h i g h pH and thermal t o l e r a n c e c h a l l e n g e s . The C h e h a l i s R i v e r s t o c k had the s m a l l e s t plasma i o n i n c r e a s e i n s a l t water but showed the l a r g e s t plasma i o n decrease i n a c i d i c waters. In some of the low pH c h a l l e n g e s the Tenderfoot Creek stock showed l e s s plasma i o n l o s s than other s t o c k s . The stock from Eagle R i v e r had the lowest plasma gl u c o s e c o n c e n t r a t i o n i i i n c r e a s e d u r i n g h a n d l i n g c h a l l e n g e s . The combined s a l t w a t e r and temperature i n c r e a s e c h a l l e n g e demonstrated the cumulative e f f e c t t h a t s t r e s s o r s can have. Sampling a s s o c i a t e d w i t h the h a n d l i n g c h a l l e n g e s r e v e a l e d a d i u r n a l f l u c t u a t i o n i n r e s t i n g plasma gl u c o s e c o n c e n t r a t i o n s . The low pH and h a n d l i n g c h a l l e n g e s showed t h a t st o c k performance and the magnitude of the response observed v a r i e d w i t h r e a r i n g c o n d i t i o n s . Although t h e r e was some v a r i a t i o n i n the magnitude of the stock response t o c h a l l e n g e s between the two r e a r i n g c o n d i t i o n s used, d i f f e r e n c e s among s t o c k s were c o n s i s t e n t . When the response t o a l l c h a l l e n g e s were assembled i n t o a r e l a t i v e c h a l l e n g e response p r o f i l e (or performance p r o f i l e ) , each s t o c k was unique. i i i T a b l e o f Contents A b s t r a c t i i Table of Contents i v L i s t of T a b l e s v L i s t o f F i g u r e s v i Acknowlegements v i i i I n t r o d u c t i o n 1 M a t e r i a l and Methods 6 R e s u l t s 16 D i s c u s s i o n 3 8 C o n c l u s i o n s 5 0 B i b l i o g r a p h y 52 Appendix 1 6 6 Appendix I I 7 1 Appendix I I I 8 0 Appendix IV 8 4 i v L i s t of T a b l e s Table I. Summary of the s t a n d a r d i z e d c h a l l e n g e s a p p l i e d t o the s i x s t o c k s of coho salmon from southern B r i t i s h Columbia 8 Table I I . Ranking f o r magnitude of d i s t u r b a n c e experienced by each of the s i x s t o c k s of coho salmon from southern B r i t i s h Columbia, Canada i n each of the s t a n d a r d i z e d c h a l l e n g e s 31 Table A-I. Means, by stock and treatment, f o r the parameters measured i n s a l t w a t e r c h a l l e n g e 1 and 2 67 Table A - I I . Means, by st o c k and treatment, f o r the parameters low pH c h a l l e n g e s 68 Table A - I I I . Means, by stock and treatment, f o r the parameters measured i n h i g h pH c h a l l e n g e s 69 Table A-IV. Means, by stock and treatment, f o r the parameters measured i n h a n d l i n g c h a l l e n g e s 70 Table B-I. Summary of the i n f o r m a t i o n t h a t was a v a i l a b l e on each of the h a t c h e r i e s from which s t o c k s i n the s i x st o c k comparison o r i g i n a t e d from 72 Table C-I. D e t a i l s on c o l l e c t i o n , h a t c h i n g and e a r l y r e a r i n g of the s t o c k s used i n the s i x st o c k comparison 81 Table C - I I . The dates and d e t a i l s of the sample weights c o l l e c t e d from the s t r a i n s i n the s i x st o c k comparison 82 Table C - I I I . Date of the s t a r t of c h a l l e n g e t e s t conducted i n the s i x stock comparison 83 v L i s t of F i g u r e s v i F i g u r e 8. Mean ±1 SE of plasma gl u c o s e o f s i x sto c k s of coho salmon from southern B r i t i s h Columbia Canada d u r i n g 30 s h a n d l i n g c h a l l e n g e 1 (8A), h a n d l i n g c h a l l e n g e 2 (8B) and h a n d l i n g c h a l l e n g e 3 (8C) 29 F i g u r e 9. Mean ±1 SE o f c o n d i t i o n f a c t o r of s i x st o c k s o f coho salmon from southern B r i t i s h Columbia Canada a t f o u r time p e r i o d s 33 F i g u r e 10. Mean ±1 SE of r e s t i n g plasma sodium c o n c e n t r a t i o n and hema t o c r i t v a l u e a t v a r i o u s times over the w i n t e r . Means pooled a c r o s s the s i x st o c k o f coho salmon from southern B r i t i s h Columbia. Temperature a t each time p e r i o d i s i n c l u d e d 36 F i g u r e 11. Mean ±1 SE of plasma gl u c o s e c o n c e n t r a t i o n of coho salmon from southern B r i t i s h Columbia, Canada sampled a t v a r i o u s times o f day 37 F i g u r e 12. R e l a t i v e response p r o f i l e of s i x s t o c k s of coho salmon from southern B r i t i s h Columbia, Canada. The mean d i s t u r b a n c e experienced by each s t o c k ( r e l a t i v e t o ot h e r s t o c k s ) i s shown f o r each type of c h a l l e n g e 46 v i i Acknowledgements The s u p e r v i s i o n , guidance and p a t i e n c e of Dr. George K. Iwama i s g r a t e f u l l y acknowledged. H i s f o r e s i g h t , energy and con f i d e n c e was i n s t r u m e n t a l i n g e t t i n g the p r o j e c t i n i t i a t e d . Thanks f o r s e e i n g the t h i n g s t h a t I c o u l d not. Funding was p r o v i d e d by the N a t u r a l S c i e n c e s and En g i n e e r i n g Research C o u n c i l o f Canada as an o p e r a t i n g g r a n t t o G.K. Iwama and a postgraduate s c h o l a r s h i p t o myself. Animals were donated by F i s h e r i e s and Oceans Canada. The management and personnel o f the s i x source h a t c h e r i e s were p a t i e n t and h e l p f u l . The r e a r i n g and c h a l l e n g i n g of f i s h c o u l d not have been done without the a s s i s t a n c e , concern and d e d i c a t i o n of E l l e n Teng, I v o r Bernatsky, Ron Creelman and Tim Y e s a k i . Thanks t o them and the many o t h e r s who helped. G r a t e f u l thanks t o my paren t s , who made me what I am. The l a r g e s t p a r t of my g r a t i t u d e goes t o Darlene and C a i t l y n , who make me what I am. v i i i I n t r o d u c t i o n Species of P a c i f i c salmon e x i s t as a s e r i e s of d i s t i n c t s u b -populations ( s t o c k s ) t h a t are r e p r o d u c t i v e l y i s o l a t e d from each o t h e r ( H o r r a l l 1981). T h i s i s o l a t i o n , when combined wi t h h a b i t a t d i f f e r e n c e s , has the p o t e n t i a l t o produce environmental a d a p t a t i o n s t h a t s t o c k s p r e s e r v e i n t h e i r genotype ( R i c k e r 1972). I t has been shown, f o r example, t h a t f i s h from s i m i l a r environments have more i n common w i t h each o t h e r than those from d i f f e r e n t environments ( H j o r t and Schreck 1981; Wilmont and Burger 1985; G h a r r e t t e t a l . 1987). I t i s a l s o p o s s i b l e t h a t i s o l a t i o n and random d r i f t of a l l e l e s can produce the gen o t y p i c v a r i a t i o n among s t o c k s ( A l l e n d o r f and U t t e r 1979; Kimura and Maruyama 1971). The unigue nature of salmon s t o c k s has become an important c o n s i d e r a t i o n i n a number of f i s h e r y f i e l d s . Management and enhancement of salmon i n the p u b l i c s e c t o r i s one example. I n d i v i d u a l s t o c k s may c a r r y s p e c i f i c and important t r a i t s t h a t have y e t t o be r e v e a l e d . Stocks can a l s o be thr e a t e n e d by a d w i n d l i n g number of r e t u r n i n g a d u l t s . P r e s e r v i n g g e n e t i c v a r i a t i o n i s o f t e n d i f f i c u l t g i v e n the s e l e c t i o n p r e s s u r e s t h a t occur d u r i n g i n t e n s i v e c u l t u r e a c t i v i t i e s such as spawning, f e r t i l i z a t i o n , r e a r i n g , 1 r e l e a s e and commercial f i s h e r i e s management (Thompson 1985; H j o r t and Schreck 1981; U t t e r e t a l . 1987; A l l e n d o r f and Phelps 1980; K a p u s c i n s k i and Lannan 1986; W i t h l e r 1988; G h a r r e t t and S h i r l e y 1985; Booking and Peterman 1988; H i l b o r n and Walters 1987). Commercial aqu a c u l t u r e i s another f i e l d concerned w i t h s t o c k s . S e l e c t i o n o f h i g h performing s t o c k s ( B a i l e y and Saunders 1984; McKay e t a l . 1984) and comparison of s t o c k s (Cheng e t a l . 1987; W i t h l e r e t a l . 1987; T o r r i s s e n 1987) are examples of some of the r e s e a r c h d i r e c t i o n s . Stocks and s t o c k s t r u c t u r e w i t h i n p o p u l a t i o n s of f i s h a l s o s t i m u l a t e i n t e r e s t i n the f i e l d of e v o l u t i o n a r y t h e o r y ( U t t e r 1981; G h a r r e t t e t a l . 1987; C l a y t o n 1981; Ga u l d i e 1984; Wehrhahn and Powell 1987). The g e n e t i c v a r i a t i o n t h a t e x i s t s among s t o c k s can be demonstrated b i o c h e m i c a l l y o r by o b s e r v i n g d i f f e r e n c e s i n phenotype. G e n e t i c d i f f e r e n c e s among s t o c k s of coho salmon (Oncorhynchus kisutch) on the west c o a s t o f North America, have been shown by e l e c t r o p h o r e t i c s e p a r a t i o n o f isoenzymes from polymorphic l o c i . An isoenzyme comparison of coho by R e i s e n b i c h l e r and Phelps (1987), suggested t h a t w h i l e s t o c k s from watersheds w i t h i n a g i v e n r e g i o n were d i s t i n c t , they shared more s i m i l a r i t i e s than those from d i f f e r e n t r e g i o n s . A l a r g e r isoenzyme study u s i n g coho from southern B r i t i s h Columbia concluded t h a t t h e r e were g e n e t i c d i f f e r e n c e s 2 between f i s h from the c o a s t a l mainland, Vancouver I s l a n d and the upper F r a s e r R i v e r (Wehrhahn and Powell 1987). H e r i t a b l e d i f f e r e n c e s among coho have a l s o been shown by o b s e r v i n g phenotype. S t u d i e s showing g e n e t i c d i f f e r e n c e s between s t o c k s f o r m e r i s t i c and b e h a v i o u r a l t r a i t s have been accomplished by o b s e r v i n g f i s h t h a t were r e a r e d i n common environments. D i f f e r e n c e s i n body conformation and swimming a b i l i t y between c o a s t a l and i n l a n d coho have been documented ( T a y l o r and McPhail 1985a, 1985b). They showed t h a t c o a s t a l s t o c k s where s h o r t e r i n l e n g t h , deeper i n body and had b e t t e r b u r s t swimming a b i l i t y than the t h i n n e r and lo n g e r i n l a n d s t o c k s . B e h a v i o u r a l d i v e r s i t y between coho p o p u l a t i o n s was demonstrated by Roseneau and McPhail (1987). They found t h a t behaviour among groups of coho was r e l a t e d t o l o c a l environment d i f f e r e n c e s . M o r p h o l o g i c a l and behaviour d i f f e r e n c e s have a l s o been shown between l a k e - r e a r e d and stream-reared j u v e n i l e coho (Swain and Holtby 1989). They, l i k e T a y l o r and McPhail (1985a, 1985b) and Roseneau and McPhail (1987), suggested t h a t the phenotypic v a r i a t i o n had a g e n e t i c b a s i s and r e p r e s e n t e d a d a p t a t i o n s t o the l o c a l h a b i t a t from which the s t o c k s o r i g i n a t e d . Other evidence f o r d i f f e r e n c e s among st o c k s t o coho salmon i n c l u d e growth and d i s e a s e r e s i s t a n c e s t u d i e s . A 3 study of growth and s u r v i v a l of v a r i o u s s t o c k s from n o r t h , c e n t r a l and southern B r i t i s h Columbia demonstrated t h a t s t o c k d i f f e r e n c e s can be complex (B. S w i f t , U n i v e r s i t y of B r i t i s h Columbia, p e r s . comm). The r e s u l t s of t h a t study showed t h a t the b e s t growing s t o c k s d i f f e r e d from s a l t water t o f r e s h water. W i t h i n the s a l t water phase of the experiment, the s t o c k t h a t showed the s m a l l e s t growth a f t e r 8 months i n seawater ended up being the one w i t h the l a r g e s t f i s h a t h a r v e s t time. The study a l s o showed t h a t m o r t a l i t y r a t e s d i f f e r e d among s t o c k s . Challenges w i t h pathogens, such as the c a u s a t i v e agent f o r b a c t e r i a l kidney d i s e a s e (BKD) Renibacterium salmoninarum (Suzumoto e t a l . 1977; McGeer e t a l . 1989) and the p a r a s i t e Ceratomyxa shasta ( E n v i r o c o n L t d . and E.V.S. C o n s u l t a n t s L t d . 1983; Ching and Parker 1989), demonstrated t h a t s t o c k s of coho can respond d i f f e r e n t l y t o d i s e a s e . In some of the s t u d i e s (Ching and Parker 1989; McGeer e t a l . 1989) the most r e s i s t a n t f i s h appeared t o be the ones from s t o c k s t h a t had p r e v i o u s l y been exposed t o the pathogen. Challenge t e s t s t h a t show d i f f e r e n c e s between groups of f i s h can be used t o assess the c o n d i t i o n of f i s h (or f i s h p o p u l a t i o n s ) and t o show the e f f e c t s of environmental s t r e s s on f i s h (Wedemeyer and McLeay 1981). In t h i s way, s t a n d a r d i z e d c h a l l e n g e t e s t s are p o t e n t i a l t o o l s i n the 4 a r t i f i c i a l p r o p a g a t i o n o f f i s h and i n s t u d i e s o f environmental impact. Such t e s t s compare the t o l e r a n c e l i m i t s and/or performance c a p a c i t i e s among groups. I t i s r e c o g n i z e d t h a t f a c t o r s such as g e n e t i c makeup can a f f e c t the responses t o c h a l l e n g e t e s t s (Schreck 1981; Wedemeyer e t a l . 1984). The s t u d i e s r e p o r t e d here were designed t o compare the performance c a p a c i t y and t o l e r a n c e l i m i t s o f s i x s t o c k s o f coho salmon from southern B r i t i s h Columbia. The work was a l s o done t o i n v e s t i g a t e the p o t e n t i a l use of c h a l l e n g e t e s t s t o r e v e a l s t o c k d i f f e r e n c e s . The t e s t s were chosen from the su g g e s t i o n s o f Wedemeyer and McLeay (1981) i n t h e i r d i s c u s s i o n of how t o measure the t o l e r a n c e of f i s h t o s t r e s s o r s u s i n g s t a n d a r d i z e d c h a l l e n g e t e s t s . S e l e c t e d p h y s i o l o g i c a l responses of j u v e n i l e f i s h from each s t o c k t o s a l t water, low pH, h i g h pH, thermal and h a n d l i n g c h a l l e n g e s were compared. 5 M a t e r i a l and Methods Animals Approximately 2,000 coho salmon were o b t a i n e d from each of s i x Canadian Department of F i s h e r i e s and Oceans Salmonid Enhancement P r o j e c t h a t c h e r i e s (see F i g u r e 1). Department of F i s h e r i e s and Oceans personnel a l l o c a t e d the f i s h a f t e r a r e q u e s t f o r s i x u n s p e c i f i e d s t o c k s . They were housed i n the Aquaculture U n i t of the Department of Animal Science a t The U n i v e r s i t y of B r i t i s h Columbia, Vancouver, Canada. The s t o c k s from the C a p i l a n o R i v e r ( s t o c k A), C h e h a l i s R i v e r ( s t o c k B), C h i l l i w a c k R i v e r ( s t o c k C), Quinsam R i v e r ( s t o c k E) and Tenderfoot Creek (s t o c k F) h a t c h e r i e s were c o l l e c t e d as eyed eggs i n March 1988. The s i x t h s t o c k ( s t o c k D) came from Eagle R i v e r hatchery i n June of 1988 as 3.7g f r y . The f i s h c o l l e c t e d were o f f s p r i n g of l a t e run a d u l t s n a t i v e t o the watershed where the hatchery was l o c a t e d ( d e t a i l s of spawning are i n c l u d e d i n Appendix C, Table I ) . R e a r i n g C o n d i t i o n s F i s h were r e a r e d i n d e c h l o r i n a t e d Vancouver C i t y t a p water (temperature 4 t o 15°C; hardness 4 mg'L"1 as CaCo 3; pH 5.8 t o 6.2). I n c u b a t i o n of eggs was done i n a Heath t r a y s t a c k w i t h a flow of 20 L'min" 1. A f t e r ponding i n troughs, s t o c k s were maintained i n separate 150 L tanks w i t h s i m i l a r 6 F i g u r e 1. Map of southern B r i t i s h Columbia, Canada, showing the approximate l o c a t i o n o f the s i x h a t c h e r i e s from which s t o c k s of f i s h were c o l l e c t e d . In the t e x t s t o c k s are r e f e r r e d t o by l e t t e r as f o l l o w s : C a p i l a n o R. coho - Stock A C h e h a l i s R. coho . - Stock B C h i l l i w a c k R. coho - Stock C Eagle R. coho - Stock D Quinsam R. coho - Stock E Tenderfoot Cr. coho - Stock F. 7 f e e d i n g r a t e s , water flow and management. The e x c e p t i o n t o t h i s was s t o c k D which was r e a r e d i n a 750 L tank from a r r i v a l u n t i l l a t e 1988 when i t was moved i n t o a s i x t h 150 L tank. During t h i s p e r i o d s t o c k i n g d e n s i t y , water flow, f e e d i n g r a t e , p h o t o p e r i o d and day t o day management of s t o c k D matched t h a t of the o t h e r s t o c k s . F i s h were f e d a commercial salmon f e e d (Ewos ST40 and ST42). Monthly samplings (see Appendix C, Table I I f o r d e t a i l s ) were used t o develop growth curve p r o j e c t i o n s (Iwama and Tautz 1981; Iwama 1982), t o m a i n t a i n f e e d i n g r a t e s a t s a t i a t i o n and t o keep tank d e n s i t i e s below 35 kg/m 3. T h i s maximum l e v e l was suggested by Wedemeyer (1976) t o a v o i d undue s t r e s s due t o crowding. As f i s h grew, and l o a d i n g d e n s i t i e s i n c r e a s e d , each s t o c k was s p l i t i n t o two r e a r i n g groups. Stocks from r e a r i n g group 1 were maintained i n the 150 L o v a l s w h i l e s t o c k s from r e a r i n g group 2 were kept i n e q u a l l y s p l i t 750 L tanks. N a t u r a l p h o t o p e r i o d was approximated f o r both groups except f o r the p e r i o d from October 1988 t o May 1989 when a 12 hour l i g h t and 12 hour dark regime was used on a l l s t o c k s i n r e a r i n g group 1. The s t o c k i n g d e n s i t i e s were s i m i l a r among s t o c k s w i t h i n groups but d i f f e r e d between groups. 8 S t a n d a r d i z e d C h a l l e n g e s At v a r i o u s times samples o f f i s h from each s t o c k were s u b j e c t e d t o c h a l l e n g e t e s t s . Challenge t e s t s i n v o l v e d simultaneous exposure of f i s h from a l l s t o c k s t o a s t r e s s o r (see T a b l e 1 f o r d e t a i l s ) . The 24 hour s a l t w a t e r c h a l l e n g e t e s t was conducted u s i n g s a l i n e water a t 30ppt NaCl f o l l o w i n g procedures o u t l i n e d by Blackburn and C l a r k e (1987). The low pH c h a l l e n g e t e s t s used a co n c e n t r a t e d HC1 s o l u t i o n t o decrease water pH t o the d e s i r e d l e v e l . The h i g h pH c h a l l e n g e s used a co n c e n t r a t e d NaOH s o l u t i o n t o a l t e r pH l e v e l s . In both cases a p e r i s t a l t i c pump (Harvard Apparatus Inc. M i l l i s , Mass., USA) was used t o meter the concentated s o l u t i o n i n t o the i n f l o w i n g water. The pH l e v e l s were measured u s i n g GK2401 g l a s s e l e c t r o d e (Radiometer, Copenhagen, Denmark) coupled t o a PHM84 pH meter (Radiometer). In h i g h pH c h a l l e n g e s 1 and 2, the pH was i n c r e a s e d t o 7.5 f o r 24 h p r i o r t o the s t a r t o f the c h a l l e n g e , a t which time i t was e l e v a t e d t o 9.4 and maintained f o r 72 h (high pH c h a l l e n g e l ) or 144 h (high pH c h a l l e n g e 2 ) . The t h i r d pH c h a l l e n g e had a r a p i d i n c r e a s e t o pH 9.3 a t the s t a r t of the c h a l l e n g e f o l l o w e d by a gr a d u a l i n c r e a s e over the next 12 h t o pH 10.0. The pH 10.0 c o n d i t i o n s were maintained f o r a f u r t h e r 12 h. The thermal t o l e r a n c e c h a l l e n g e i n v o l v e d i n c r e a s i n g the temperature by 9 Challenge t r i a l group Temp water Mean t e s t Date l e n g t h n used* 3 (°C) change wt(g) S a l t w a t e r 1 10/88 24 h 15 1 13 30 ppt 9.5 Sa l t w a t e r 2 12/88 24 h 9 1 7 30ppt+4°C 16.1 Low pH 1 12/88 24 h 9 1 7 pH 3.55 16.6 Low pH 2 05/89 20 h 6 1 9 pH 3.65 24.6 Low pH 3 05/89 20 h 6 2 9 pH 3.65 17.4 LOW pH 4 05/89 24 h 6 1 9 pH 3.75 23.5 LOW pH 5 05/89 24 h 6 2 9 pH 4.10 17.0 High pH 1 11/88 72 h 6 1 9 pH 9.40 12.8 High pH 2 11/88 144 h 6 1 9 pH 9.40 12.8 High pH 3 02/89 24 h 6 1 4 pH 10.0 17.6 Thermal 03/89 22 h 8 1 6 l°C/h N.A. Handling 1 06/89 18 h 6-7 d 1 10 30s d i p 26.7 Handling 2 06/89 18 h 7-8 d 2 10 30s d i p 25.2 Handling 3 06/89 18 h 5-8 d 1 10 30s d i p 26.8 a - Number of f i s h per s t o c k used i n c h a l l e n g e . b - Rearing group the st o c k came from f o r t h a t c h a l l e n g e . d - Number o f f i s h per s t o c k per sample time. T a b l e I. Summary of s t a n d a r d i z e d c h a l l e n g e s a p p l i e d t o the s i x s t o c k s o f coho salmon from southern B r i t i s h Columbia. 10 1°C per hour as o u t l i n e d by McLeay and Gordon (1978). The h a n d l i n g c h a l l e n g e s were 30 second (s) d i p net s t r e s s e s as d e s c r i b e d by Barton e t a l . (1986) wit h sampling a t 0, 1 (or 1.5), 3, 6, 9, 12 and 18 hours ( h ) . P r o t o c o l Unless otherwise noted, the f o l l o w i n g g e n e r a l procedures were c a r r i e d out f o r a l l t e s t s . The f i s h were: s t a r v e d f o r 12 t o 24 h; n o n s e l e c t i v e l y n e t t e d from r e a r i n g tanks; f u l l y a n a e s t h e t i z e d ; measured f o r weight and l e n g t h ; t r a n s f e r r e d t o a 48 L c h a l l e n g e box. T h i s box was made of b l a c k perspex and was d i v i d e d i n t o compartments so t h a t each s t o c k c o u l d be housed and sampled s e p a r a t e l y but maintained i n a common water. Normal r e a r i n g water a t a flow r a t e of 4 L ' m i n - 1 was s u p p l i e d t o the box i n a flow through manner. F i s h were c h a l l e n g e d a f t e r a 24 h a c c l i m a t i o n p e r i o d . At the end of a t r i a l , b l o o d was c o l l e c t e d from the caudal v a s c u l a t u r e o f euthanized f i s h (NaHC0 3 b u f f e r e d t r i c a i n e methanesulfonate a t 300 mg'L" 1 and/or a blow t o the head). A f t e r hematocrit v a l u e s were c a l c u l a t e d , plasma was saved and s t o r e d a t -80°C f o r subsequent d e t e r m i n a t i o n s o f plasma sodium i o n c o n c e n t r a t i o n ( [ N a + ] p 1 ) and plasma c h l o r i d e i o n c o n c e n t r a t i o n ( [ C l ~ ] p ] _ ) . In some t r i a l s t c l ~ ] p i was not measured. C o n t r o l data were c o l l e c t e d f o r each t e s t by 11 running a p a r a l l e l t r i a l t h a t used a l l of the c h a l l e n g e procedures except the environmental change. The s a l i n e , thermal t o l e r a n c e and h a n d l i n g experiments had m o d i f i c a t i o n s of the g e n e r a l procedures a l r e a d y d i s c u s s e d . The s a l t w a t e r c h a l l e n g e s used a water r e c i r c u l a t i o n r a t h e r than a flow through system. At the s t a r t of c h a l l e n g e s , a 15 L volume of water was removed and r e p l a c e d w i t h a c o n c e n t r a t e d sea s a l t ( B i o - s e a , C a l i f o r n i a Aquarium Supply House, San C a r l o s , Ca., USA) s o l u t i o n s u f f i c i e n t t o b r i n g the water t o the d e s i r e d s a l i n i t y . Water was a e r a t e d and temperature maintained i n s a l t w a t e r c h a l l e n g e 1. The second s a l t w a t e r c h a l l e n g e had c o n t r o l s and two c h a l l e n g e c o n d i t i o n s . The f i r s t c h a l l e n g e was a 4°C i n c r e a s e i n water temperature w h i l e the o t h e r combined t h i s temperature i n c r e a s e w i t h s a l t w a t e r . The thermal t o l e r a n c e t e s t d i d not have any c o n t r o l s and the data c o l l e c t i o n c o n s i s t e d of n o t i n g the temperature a t which f i s h e i t h e r l o s t e q u i l i b r i u m or d i e d . In t h a t t e s t , water was r e c i r c u l a t e d a t 3 L'min" 1 and f r e s h water was added a t a r a t e of 0.85 L * m i n - 1 . The h a n d l i n g c h a l l e n g e s used a l a r g e r c h a l l e n g e box (150 L, p l e x i g l a s s ) and plasma was analyzed f o r g l u c o s e . There was no a c c l i m a t i o n p e r i o d and the 0 hour measurement se r v e d as a c o n t r o l . As p a r t of the second and t h i r d h a n d l i n g c h a l l e n g e s , subsamples of f i s h were 12 F i g u r e 2 . Diagram of the p e r s p e x / p l e x i g l a s s , s i x s l o t t e d boxes (one 48 L, the o t h e r 150 L) used t o c h a l l e n g e the s i x s t o c k s from southern B r i t i s h Columbia, Canada. The s i x hinged tops (one t o each compartment) are not shown. 13 m o r p h o l o g i c a l l y indexed f o r t h e i r stage of s m o l t i f i c a t i o n . The f o u r l e v e l index (1 f o r p a r r t o 4 f o r smolt) d i s c u s s e d by Gorbman e t a l . (1982) was used. Weight and l e n g t h data c o l l e c t e d d u r i n g t r i a l s and sample weighings, were used t o c a l c u l a t e the c o n d i t i o n f a c t o r (KF = g'cm~ 3 ,100) of i n d i v i d u a l f i s h . Assays Plasma i o n c o n c e n t r a t i o n s were determined u s i n g flame photometry f o r [ N a + ] p l (Model 410, Corning Instruments, England) and c o u l o m e t r i c t i t r a t i o n (Chloridometer, Haakebuchler Instruments L t d . , NJ., USA.) f o r [ C l ^ J p ^ . Glucose c o n c e n t r a t i o n s were measured c o l o u r i m e t r i c a l l y by the g l u c o s e oxidase method (Sigma D i a g n o s t i c s , S t . L o u i s , MO., USA, procedure No. 510) u s i n g a Shimadzu UV-VTS Spectrophotometer UV-160 (Shimadzu Corp., Kyoto, Japan) a t a wavelength of 450 nm. S t a t i s t i c s Means f o r each s t o c k f o r measured parameters under c o n t r o l and c h a l l e n g e c o n d i t i o n s were t e s t e d f o r s i g n i f i c a n t d i f f e r e n c e s by ANOVA. A s i x ( s t o c k s ) by two (water treatments) f a c t o r i a l experiment w i t h completely random d e s i g n was used ( S t e e l and T o r r i e 1980). A one way ANOVA 14 was used t o compare s t o c k s i n the temperature and h a n d l i n g t r i a l s as w e l l as the c o n d i t i o n f a c t o r d a t a . Where a p p r o p r i a t e , s t o c k means were compared u s i n g Tukey's HSD t e s t ( W i l k i n s o n 1988). In the h a n d l i n g c h a l l e n g e s Dunnett's t e s t (Zar 1984) was used t o compare each 0 h mean t o subsequent sample means. The e r r o r l e v e l f o r a l l s t a t i s t i c a l t e s t s was 0.05 (a=0.05). The response of s t o c k s was a l s o compared a c r o s s c h a l l e n g e s . For each c h a l l e n g e , the s t o c k s were ranked a c c o r d i n g t o the magnitude of change experienced. The magnitude of change was a measure t h a t e v a l u a t e d the d i f f e r e n c e between mean c o n t r o l and mean c h a l l e n g e v a l u e s f o r a s t o c k f o r e i t h e r [Na +]p^, plasma gl u c o s e c o n c e n t r a t i o n , or c r i t i c a l thermal maximum (depending on the c h a l l e n g e ) . Ranks were compared w i t h the K r u s k a l - W a l l i s one way ANOVA. 15 R e s u l t s The mean and standard e r r o r of parameters measured i s shown f o r each s t o c k i n each c h a l l e n g e e i t h e r i n Appendix A, t a b l e s I through IV or i n f i g u r e s 3 through 11 which are i n the t e x t . In each of the c h a l l e n g e t e s t s , u n l e s s otherwise noted, t h e r e was no s i g n i f i c a n t d i f f e r e n c e among s t o c k s f o r mean f i s h weight. S a l t w a t e r C h a l l e n g e s The f i s h used i n the s a l t w a t e r c h a l l e n g e o f October 1988 a l l experienced a weight l o s s and hema t o c r i t v a l u e decrease d u r i n g the 48 h (24 h a c c l i m a t i o n + 24 h c h a l l e n g e ) i n the c h a l l e n g e box. Average weight l o s s was l e s s i n c o n t r o l f i s h than i n c h a l l e n g e d f i s h (Appendix A, Table I ) . S a l t water r e s u l t e d i n decreased h e m a t o c r i t v a l u e s f o r a l l s t o c k s . Stocks B, C and D had s i g n i f i c a n t l y lower h e m a t o c r i t v a l u e s under c h a l l e n g e c o n d i t i o n s . Plasma i o n c o n c e n t r a t i o n s were s i g n i f i c a n t l y i n c r e a s e d f o r a l l s t o c k s when they were exposed t o s a l t water and the magnitude of the i n c r e a s e d i f f e r e d between s t o c k s . Under c o n t r o l c o n d i t i o n s t h e r e were no d i f f e r e n c e s between s t o c k s . The o v e r a l l mean was 139 mEq-L" 1 f o r [ N a + ] p l and 132 mEq'L" 1 f o r [ C l ~ ] p i . In s a l t water, stock B showed an i n c r e a s e d [ N a + ] p i , however, i t was s i g n i f i c a n t l y l e s s than the i n c r e a s e s o t h e r s t o c k s experienced ( F i g . 3 ) . Stocks A and C had i n t e r m e d i a t e [ N a + ] p 1 i n c r e a s e s , w h i l e D, E and F had the h i g h e s t . The [ C l ~ ] p ^ were a l s o s i g n i f i c a n t l y i n c r e a s e d under c h a l l e n g e c o n d i t i o n s but t h e r e were fewer s i g n i f i c a n t d i f f e r e n c e s among s t o c k s . The A, B and C s t o c k s had s m a l l e r [ C l ~ ] p 1 i n c r e a s e s than E, F and G. The second s a l t w a t e r c h a l l e n g e was a combined temperature i n c r e a s e and s a l i n e c h a l l e n g e . Means f o r [Na+] p l were lowest f o r c o n t r o l s , i n t e r m e d i a t e i n the temperature i n c r e a s e o n l y c o n d i t i o n s and h i g h e s t f o r f i s h exposed t o a temperature i n c r e a s e and s a l t w a t e r . Stocks A and C were the o n l y groups t h a t showed s i g n i f i c a n t [Na +]p^ i n c r e a s e s and s t o c k D reco r d e d the s m a l l e s t i n c r e a s e when c o n t r o l s were compared t o the temperature i n c r e a s e o n l y treatment ( F i g . 4 ) . In the temperature p l u s s a l i n e treatment, m o r t a l i t i e s o c c u r r e d i n a l l s t o c k s . M o r t a l i t y r a t e s were h i g h e s t f o r s t o c k s D and C and lowest f o r s t o c k s A and F. 17 I 1—1 a 4 cd CD 195 180 165 150 135 120 a o b-a o A B a o a o C D S t o c k d r a_ o a o E F F i g u r e 3. Sa l t w a t e r c h a l l e n g e 1. Plasma sodium c o n c e n t r a t i o n i n c o n t r o l (open) and s a l t water ( f i l l e d ) treatments f o r s i x s t o c k s of coho salmon from southern B r i t i s h Columbia Canada. Mean ±1 SE, n=15 and those tagged w i t h the same l e t t e r are not s t a t i s t i c a l l y d i f f e r e n t (P<0.05). i a 220 v V 1—1 cd 0) 200-180 160-140 if 1 Te • 1 o if 1 o o o 1 I • 1 o E F Stock F i g u r e 4. Sa l t w a t e r and 4°C i n c r e a s e c h a l l e n g e . Plasma sodium c o n c e n t r a t i o n i n c o n t r o l (open c i r c l e s ) , 4°C i n c r e a s e ( f i l l e d t r i a n g l e s ) and 4°C p l u s s a l t water ( f i l l e d c i r c l e s ) f o r s i x s t o c k of coho salmon from southern B r i t i s h Columbia, Canada. Mean ± 1SE, n=9 and those tagged w i t h an "e" are s i g n i f i c a n t l y d i f f e r e n t (P<0.05) from c o n t r o l means f o r t h a t s t o c k . Means w i t h an " f " are s i g n i f i c a n t l y d i f f e r e n t (P<0.05) from both c o n t r o l and temperature i n c r e a s e means. Open t r i a n g l e s marked wit h a "*" i n d i c a t e s t o c k s t h a t had 100% m o r t a l i t y under temperature i n c r e a s e and s a l i n e c o n d i t i o n s . 19 Low pH Ch a l l e n g e s In most of the low pH c h a l l e n g e t e s t s , a c i d i c c o n d i t i o n s r e s u l t e d i n h i g h e r h e m a t o c r i t v a l u e s and s i g n i f i c a n t l o s s of plasma i o n s f o r a l l s t o c k s . In low pH c h a l l e n g e 1 t h e r e were no s i g n i f i c a n t d i f f e r e n c e s among s t r a i n s f o r f i s h weight both b e f o r e and a f t e r the c h a l l e n g e , although weight l o s s i n c h a l l e n g e d f i s h was g e n e r a l l y l e s s than c o n t r o l s . Water c o n d i t i o n s ( c o n t r o l o r low pH) had a s i g n i f i c a n t e f f e c t on average h e m a t o c r i t v a l u e but t h e r e were no d i f f e r e n c e s among s t o c k s w i t h i n each of these treatments. There was a s i g n i f i c a n t decrease i n [ N a + ] p l f o r a l l s t o c k s i n low pH water. Stock B had a much h i g h e r l o s s of [ N a + ] p 1 than a l l o t h e r s t o c k s ( F i g . 5A). Mean [ C l ' l p ^ f o r a l l s t o c k s was s i g n i f i c a n t l y reduced i n a c i d waters with s t o c k B s u f f e r i n g the l a r g e s t l o s s e s (Appendix A, Table I I ) . The low pH experiments of May 1989, showed r e s u l t s t h a t were g e n e r a l l y c o n s i s t e n t w i t h those o f the December c h a l l e n g e . In low pH c h a l l e n g e 2, a c i d i c c o n d i t i o n s r e s u l t e d i n h i g h e r h e m a t o c r i t v a l u e s and lower [Na +]p^ (Appendix A, Table I I ) . There were no hema t o c r i t v a l u e d i f f e r e n c e s among s t o c k s under e i t h e r c o n t r o l o r c h a l l e n g e c o n d i t i o n s . In low pH water, s t o c k E was the o n l y one t o show no s i g n i f i c a n t i n c r e a s e i n hema t o c r i t v a l u e when 20 F i g u r e 5. Low pH c h a l l e n g e 1 (5A) and low pH c h a l l e n g e 3 (5B). Plasma sodium c o n c e n t r a t i o n i n c o n t r o l (open) and low pH ( f i l l e d ) treatments f o r s i x s t o c k s of coho salmon from southern B r i t i s h Columbia, Canada. Mean ±1 SE, n=9 (5A) and n=6 (5B), and i n each graph those tagged w i t h the same l e t t e r are not s t a t i s t i c a l l y d i f f e r e n t (P<0.05). 21 165 150 o o o o a6 a-O 5. & 135-120-105 CT 1 1 cT 1 cT 1 CX 165 cd ^ 150 cd CD 135-o • b o d O d O O T • c 'a 6 d 120 T f a b 'a b 105 B C D E F S t o c k 22 compared t o i t s c o n t r o l . A l l s t o c k s had s i m i l a r [Na +]p^ under c o n t r o l and c h a l l e n g e c o n d i t i o n s . When mean [ N a + ] p 1 f o r s t o c k s i n the low pH treatment were ranked, stock B was lowest. In low pH c h a l l e n g e 3, a c i d water r e s u l t e d i n a l l s t o c k s showing h e m a t o c r i t v a l u e i n c r e a s e s and t h e r e were s i g n i f i c a n t d i f f e r e n c e s between s t o c k s f o r [Na +]p^. The low pH c o n d i t i o n s produced s i g n i f i c a n t l y reduced [Na+jpj f o r a l l s t o c k s except E ( F i g . 5B). Stock B d i s p l a y e d the g r e a t e s t [ N a + ] p l l o s s . T h i s was the o n l y low pH c h a l l e n g e t h a t had m o r t a l i t i e s : deaths o c c u r r e d i n st o c k s C and F (Appendix A, Table I I ) . The f o u r t h and f i f t h low pH c h a l l e n g e s had i n t e r m e d i a t e pH v a l u e treatments. At pH 3.75 (low pH c h a l l e n g e 4) the r e were s i g n i f i c a n t i n c r e a s e s i n hemat o c r i t v a l u e f o r s t o c k s B, C and D and no change i n [Na +]p^ f o r a l l s t o c k s . When a pH of 4.1 was used (low pH c h a l l e n g e 5 ), t h e r e was an i n c r e a s e i n h e m a t o c r i t v a l u e i n s t o c k s A, B, C and F and a s l i g h t but s i g n i f i c a n t decrease i n [ N a + ] p l f o r s t o c k s A, B and C (Appendix A, Table I I ) . High pH Cha l l e n g e s The t h r e e h i g h pH c h a l l e n g e s showed few s i g n i f i c a n t d i f f e r e n c e s . Hematocrit v a l u e s were u n a f f e c t e d by the / 23 c h a l l e n g e c o n d i t i o n s a t 72 h (high pH c h a l l e n g e l ) , but tended t o be hi g h e r than c o n t r o l s a t 144 h (high pH c h a l l e n g e 2 ) . Stocks B and C were the o n l y s t o c k s t o show s i g n i f i c a n t i n c r e a s e s i n mean hemat o c r i t v a l u e (Appendix A, Table I I I ) . At 72 h, mean [ N a + ] p 1 was s i g n i f i c a n t l y decreased from c o n t r o l v a l u e s i n s t o c k B, C and D (Appendix A, Table I I I ) and a t 144 h o n l y st o c k F was h i g h e r ( F i g . 6 ) . Mean [ C l ~ ] p ^ was not a l t e r e d s i g n i f i c a n t l y by the h i g h pH waters a t e i t h e r time except f o r st o c k F which was s i g n i f i c a n t l y h i g h e r than i t s c o n t r o l v a l u e a t 72 h. The t h i r d h i g h pH c h a l l e n g e exposed f i s h t o a hi g h e r pH f o r a s h o r t e r time. Mean [ N a + ] p 1 and [Cl'jp^^ d i d not d i f f e r s i g n i f i c a n t l y among s t o c k s o r treatment except f o r st o c k A which had a s i g n i f i c a n t l y lower [Na +]p^ l e v e l when c h a l l e n g e d (Appendix A, Table I I I ) . Thermal T o l e r a n c e Challenge The temperature t o l e r a n c e c h a l l e n g e d i d not show d i f f e r e n c e s among st o c k s ( F i g . 7 ) . A l l f i s h s u r v i v e d u n t i l 23°C but none p a s t 25.5°C. The average temperature a t which death o r d i s e q u i l i b r i u m o c c u r r e d (the c r i t i c a l thermal maximum or CTM) d i d not d i f f e r between s t o c k s . Stock C had the lowest CTM and stock D the h i g h e s t ( F i g . 7 ) . 24 160 l 0) 150 140 T O 1 T i T O i T 1 f o o i 1 130 C D S t o c k E F F i g u r e 6. High pH c h a l l e n g e 2. Plasma sodium c o n c e n t r a t i o n i n c o n t r o l (open) and h i g h pH ( f i l l e d ) treatments f o r s i x st o c k s o f coho salmon from southern B r i t i s h Columbia, Canada. Mean ±1 SE, n=6 and an "e" i n d i c a t e s c h a l l e n g e means s i g n i f i c a n t l y d i f f e r e n t (P<0.05) than c o n t r o l means f o r t h a t s t o c k . 25 F i a u r e 7 T h e r m a l t o l e r a n c e t e s t . C r i t i c a l t h e r m a l maxima offit s t o c k s o r c o h o s a l m o n f r o m s o u t h e r n B r i t i s h C o l u m b i a , ctnSda. Mean t e m p e r a t u r e ( o C ) a t d i s e q u i l i b r i u m o r d e a t h ± 1 S E , n=8 a n d t h o s e t a g g e d w i t h t h e same l e t t e r a r e n o t s t a t i s t i c a l l y d i f f e r e n t ( P < 0 . 0 5 ) . 26 H a n d l i n g C h a l l e n g e s In the f i r s t of the t h r e e h a n d l i n g c h a l l e n g e s , which s t a r t e d i n the l a t e a f t e r n o o n (17:00), t h e r e were no mean hemato c r i t v a l u e o r plasma gl u c o s e c o n c e n t r a t i o n d i f f e r e n c e s between s t o c k s a t 0 h. When v a l u e s a t subsequent sampling times were compared t o these c o n t r o l measurements, a l l s t o c k s showed no change i n hematocrit v a l u e (Appendix A, Table IV) but s i g n i f i c a n t i n c r e a s e s i n plasma gl u c o s e c o n c e n t r a t i o n ( F i g . 8A). R e l a t i v e t o oth e r s t o c k s , the magnitude of glu c o s e c o n c e n t r a t i o n i n c r e a s e was s m a l l e s t f o r s t o c k s D and C and g r e a t e s t f o r s t o c k s F and A. The second h a n d l i n g c h a l l e n g e was s t a r t e d a t 12:00 and a t 0 h t h e r e were no mean hemat o c r i t v a l u e (Appendix A, Table IV) or mean plasma gl u c o s e c o n c e n t r a t i o n ( F i g . 8B) d i f f e r e n c e s among the s t o c k s . At a l l sampling times, f o r a l l s t o c k s except C, no change i n mean hemat o c r i t v a l u e from 0 h l e v e l s was observed. Stock C had a s i g n i f i c a n t l y i n c r e a s e d h e m a t o c r i t v a l u e a t 18 h. A l l s t o c k s showed a s i g n i f i c a n t r i s e i n mean glucose c o n c e n t r a t i o n from 0 h samples a t one or more of the sampling times except s t o c k D. Stock A had the l a r g e s t i n c r e a s e i n glu c o s e c o n c e n t r a t i o n . The s m o l t i f i c a t i o n index data showed t h a t a l l s t o c k s were 27 F i g u r e 8 . Handling c h a l l e n g e 1 (8A), h a n d l i n g c h a l l e n g e 2 (8B) and h a n d l i n g c h a l l e n g e 3 (8C). Plasma glucose c o n c e n t r a t i o n of s i x s t o c k s of coho salmon from southern B r i t i s h Columbia Canada sampled a t O , 1 (or 1.5), 3, 6, 9, 12 and 18 h a f t e r a d i p net c h a l l e n g e . Mean ±1 SE, n=5 t o 8 and open c i r c l e s are not s t a t i s t i c a l l y d i f f e r e n t (P<0.05) from the 0 h v a l u e s f o r t h a t s t o c k . 28 Mean plasma glucose cone, (mg-dl 1) s i m i l a r with an o v e r a l l mean index v a l u e of 3.97 (Appendix A, Table I V ) . The t h i r d h a n d l i n g c h a l l e n g e , l i k e the second, was s t a r t e d a t 12:00. Mean hemat o c r i t v a l u e s among s t o c k s were d i f f e r e n t a t 0 h wit h s t o c k C being lowest (Appendix A, Tabl e I V ) . Over the course of the sampling t h e r e was no s i g n i f i c a n t h ematocrit v a l u e change from i n i t i a l v a l u e s f o r any s t o c k s . Mean r e s t i n g (0 h) plasma glucose c o n c e n t r a t i o n s d i d not var y between s t o c k s ( F i g . 8C). Stock A showed the l a r g e s t i n c r e a s e i n plasma gl u c o s e c o n c e n t r a t i o n w h i l e s t o c k D was the o n l y one t h a t d i d not show a s i g n i f i c a n t i n c r e a s e a t any of the sampling times. For a l l s t o c k s t h e r e were no s i g n i f i c a n t d i f f e r e n c e s between 0 h and 18 h samples. The s m o l t i f i c a t i o n index f o r stock A was s i g n i f i c a n t l y lower than t h a t of o t h e r s t o c k s . The mean index f o r st o c k A was 3.4 while o t h e r s t o c k s ranged from 3.90 t o 4.00 (Appendix A, Table I V ) . Stock response a c r o s s c h a l l e n g e s When st o c k response was ranked f o r each of the c h a l l e n g e s t h e r e were c o n s i s t e n t d i f f e r e n c e s w i t h i n the repeated c h a l l e n g e s but not between c h a l l e n g e s (see Tab l e I I ) . W i t h i n the low pH c h a l l e n g e s s t o c k B c o n s i s t e n t l y ranked as the group with the h i g h e s t d i s t u r b a n c e . The mean 30 Stock A B C D E F S a l t water 1 2 1 3 5 4 6 4°C i n c r e a s e 5 3 6 2 1 4 S a l t water + 4°C 3 2 6 5 4 1 Thermal (l°C/h) 2 3 1 6 4 5 High pH 1 5 6 2 4 1 3 High pH 2 5 6 1 4 2 3 High pH 3 1 5 3 6 2 4 Mean High pH 3.7 5.7 2.0 4.7 1.7 3.3 Low pH 1 5 6 2 1 4 3 Low pH 2 1 6 2 5 3 4 Low pH 3 2 5 4 6 3 1 Low pH 4 3 6 5 2 1 4 Low pH 5 2 5 4 6 3 1 Mean Low pH 2.6 5.6 3.4 4.0 2.8 2.6 Handling 1 5 4 2 1 3 6 Handling 2 6 2 3 1 5 4 Handling 3 6 5 2 1 3 4 Mean Handling 5.7 3.7 2.3 1.0 3.7 4.7 T a b l e I I . The rank, by s t o c k and c h a l l e n g e t e s t f o r the magnitude of change between c o n t r o l and c h a l l e n g e parameters ( e i t h e r [ N a + ] p 1 , plasma gl u c o s e c o n c e n t r a t i o n or CTM). A rank of 1 denotes the s m a l l e s t change i n t h a t c h a l l e n g e w h i l e 6 i n d i c a t e s the l a r g e s t . Where c h a l l e n g e s were repeated, the mean rank f o r t h a t type of c h a l l e n g e i s i n c l u d e d . 31 rank d i f f e r e d between s t o c k s w i t h s t o c k B being h i g h e s t and st o c k s C and E the lowest. The h a n d l i n g c h a l l e n g e s a l s o showed a s i g n i f i c a n t d i f f e r e n c e among s t o c k s f o r mean rank. Stock D had the lowest mean rank and A had the h i g h e s t . The t h r e e h i g h pH c h a l l e n g e s showed t h a t even though t h e r e were few d i f f e r e n c e s among s t o c k s f o r parameters measured, th e r e were s i g n i f i c a n t d i f f e r e n c e s i n rank of magnitude of [Na +]p^ change. The mean rank was h i g h e s t f o r st o c k B and lowest f o r s t o c k s C and E. When the rankings were compared a c r o s s a l l of the c h a l l e n g e t e s t s , t h e r e were no s i g n i f i c a n t d i f f e r e n c e s among s t o c k s . Other O b s e r v a t i o n s The weight and l e n g t h data, c o l l e c t e d i n December 1988, January 1989, February 1989 and May 1989, demonstrated t h a t c o n d i t i o n f a c t o r (KF) changed over time and t h a t t h e r e were d i f f e r e n c e s among st o c k s ( F i g . 9 ) . At each of the 4 times, s t o c k D had s i g n i f i c a n t l y lower mean KF v a l u e . Across the sampling times, a l l s t o c k s except C and F, showed a s i g n i f i c a n t decrease i n KF. The decrease i n KF o c c u r r e d between January and February f o r st o c k s A and E. The KF d e c l i n e i n s t o c k s B and D took p l a c e between February and May. 32 1.35i CD Dec '88 ^ J a n '89 Feb '89 ¥ZZ1 May '89 En CD 1.25 S 1.15-1.05 T \ \ x \ x \ 8 \ \ \ X a A B / I / / / / / / / / / / / / / / / / / / I bTb \ x T b a \ a X X x £/ X / X / / \ / / N M / C D E F Stock F i g u r e 9. C o n d i t i o n f a c t o r of s i x s t o c k s of coho salmon from southern B r i t i s h Columbia Canada a t f o u r time p e r i o d s . Mean ± 1 SE and means tagged w i t h a "b" are s i g n i f i c a n t l y lower (P<0.05) than o t h e r s t o c k s a t t h a t sampling time and an "a" denotes means s i g n i f i c a n t l y lower (P<0.05) than December 1988 measures f o r t h a t s t o c k . 33 A comparison of r e a r i n g groups 1 and 2 was c a r r i e d out u s i n g h e m a t o c r i t v a l u e s and [ N a + ] p 1 data c o l l e c t e d d u r i n g low pH c h a l l e n g e s and glu c o s e c o n c e n t r a t i o n data from h a n d l i n g c h a l l e n g e s (see Table 1 f o r group use d e t a i l s ) . In u n a l t e r e d water c o n d i t i o n s ( c o n t r o l s ) , group 1 f i s h had he m a t o c r i t v a l u e s t h a t were s i g n i f i c a n t l y h i g h e r than group 2 f i s h . In c o n t r a s t , group 1 c o n t r o l s had s i g n i f i c a n t l y lower [Na +]p^ than group 2. When c h a l l e n g e d a t pH 3.65, some group 2 s t o c k s showed m o r t a l i t i e s w h i l e no f i s h from any of the group 1 s t o c k s d i e d . There were no d i f f e r e n c e i n r e s t i n g g l u c o s e c o n c e n t r a t i o n s among s t o c k s or between r e a r i n g groups ( F i g . 8A, 8B and 8C). The magnitude of mean plasma gl u c o s e c o n c e n t r a t i o n peak d i f f e r e d between groups f o r most s t o c k s . Stocks A, C, E and F had peak glucose c o n c e n t r a t i o n s much h i g h e r f o r group 2 than f o r group 1. Observations on r e s t i n g f i s h over time were assembled by combining the c o n t r o l data from each of the s a l i n e and pH c h a l l e n g e s . There were few s i g n i f i c a n t d i f f e r e n c e s i n r e s t i n g i o n c o n c e n t r a t i o n s and hematocrit v a l u e s among s t o c k s . Ion c o n c e n t r a t i o n i n r e s t i n g f i s h , e s p e c i a l l y [ N a + ] p 1 , changed s i g n i f i c a n t l y i n the p e r i o d from October t o May. As r e a r i n g temperature decreased from 13 t o 4°C, t h e r e was an i n c r e a s e i n [ N a + ] p 1 and decrease i n hema t o c r i t v a l u e 34 ( F i g . 10). The [Cl~]p]^ measurements were u s u a l l y more v a r i a b l e than [Na +]p^ measurements. The sampling conducted w h i l e p r e p a r i n g f o r the h a n d l i n g c h a l l e n g e s , and the t h r e e c h a l l e n g e s themselves, p r o v i d e d i n f o r m a t i o n on r e s t i n g plasma glucose l e v e l s and glu c o s e response d i f f e r e n c e s among groups. There were s i g n i f i c a n t d i f f e r e n c e s between r e s t i n g g lucose l e v e l s a t d i f f e r e n t times of day. As the day progressed, t h e r e was a decrease i n plasma gl u c o s e c o n c e n t r a t i o n i n r e s t i n g f i s h ( F i g . 11). A s t a r v a t i o n p e r i o d of 24 h d i d not a f f e c t the mean glucose c o n c e n t r a t i o n . At one sampling time, a 42 h s t a r v a t i o n p e r i o d produced s i g n i f i c a n t l y lower mean plasma glucose c o n c e n t r a t i o n . 35 F i g u r e 10. Mean r e s t i n g plasma sodium c o n c e n t r a t i o n (open bar) and he m a t o c r i t v a l u e ( c r o s s - h a t c h e d bar) d u r i n g d i f f e r e n t months i n the w i n t e r and s p r i n g of 1988/89. Mean ± 1SE pooled a c r o s s the s i x s t o c k s of coho salmon from southern B r i t i s h Columbia, Canada. The l a b e l l e d open t r i a n g l e s i n d i c a t e the average temperature of the water f o r t h a t month. Mean tagged w i t h the same l e t t e r (a,b and c f o r plasma sodium and d, e and f f o r hematocrit) are not s t a t i s t i c a l l y d i f f e r e n t (P<0.05). The n numbers are 89 f o r Oct., 73 f o r Nov., 53 f o r D e c , and 36 f o r Feb., Apr. and May. 36 140 o o o cu m o o a a cd cu a 120-100 8 0 -60 «1 00:00 o 07:30 Si b_L c C T C XI o -* CO :00 12:00 13:00 17:00 19:30 Hour of Day F i g u r e 11. Plasma gl u c o s e c o n c e n t r a t i o n o f coho salmon from southern B r i t i s h Columbia, Canada sampled a t v a r i o u s times of day. Mean ±1 SE, n=16 f o r 00:00, n=7 and n=12 f o r 07:00, n=l2 and n=19 f o r 11:00, n=47 and n=43 f o r 12:00, n=9 f o r 13:00, n=10 and n=42 f o r 17:00, n=9 f o r 19:30, and those tagged w i t h the same l e t t e r are not s i g n i f i c a n t l y d i f f e r e n t (P<0.05) from each o t h e r . The s t a r v a t i o n p e r i o d p r i o r t o sampling i s shown a t the base of each bar. 37 D i s c u s s i o n The f i r s t s a l t w a t e r c h a l l e n g e showed t h a t some st o c k s were a b l e t o perform w e l l i n s a l i n e c o n d i t i o n s , although l i f e h i s t o r y i n f o r m a t i o n would not have p r e d i c t e d t h a t r e s u l t . While stock B f i s h were most a b l e t o r e g u l a t e [ N a + ] p 1 and c o u l d be c o n s i d e r e d as f u n c t i o n a l smolts, s t o c k s A and C may a l s o have been competent as they were most s u c c e s s f u l i n m a i n t a i n i n g [ C l ~ ] p l . F i s h t h a t w i l l s u r v i v e and grow i n s a l t water should be a b l e t o r e g u l a t e [ N a + ] p l t o 170 mEq*L _ 1 or l e s s i n a 24 h s a l t w a t e r c h a l l e n g e ( C l a r k e and Blackburn 1977; Iwata e t a l . 1982; Johnson and H e i f e t z 1988). Although f i s h w i t h h i g h e r [ N a + ] p l i n a c h a l l e n g e may s u r v i v e i n s a l i n e c o n d i t i o n s , i n the long term, growth w i l l be compromised ( C l a r k e 1982). S u r v i v a l i n s a l t water has been shown t o be r e l a t e d t o the number of c h l o r i d e c e l l s and the Na +/K + ATPase a c t i v i t y a t the g i l l (Richman e t a l . 1987). Other f a c t o r s such as kidney and gut i o n t r a n s p o r t and hormone l e v e l s ( F o s k e t t e t a l . 1983) may a l s o i n f l u e n c e osmoregulatory f u n c t i o n s . The r e s u l t s of the two s a l t w a t e r c h a l l e n g e s , when combined, i l l u s t r a t e the cumulative e f f e c t s of s t r e s s . There i s a b i o e n e r g i c c o s t a s s o c i a t e d w i t h m a i n t a i n i n g 38 homeostasis under s t r e s s f u l c o n d i t i o n s and as s t r e s s e s accumulate, animals are l e s s a b l e t o compensate (Barton and Schreck 1987b) . Stock A was s e n s i t i v e t o the temperature i n c r e a s e treatment but had fewer m o r t a l i t i e s than o t h e r s t o c k s under the d u a l s t r e s s of temperature i n c r e a s e and s a l i n e water. T h i s same stock had i n t e r m e d i a t e i o n changes i n the e a r l i e r s a l t w a t e r c h a l l e n g e . Stock D which had l a r g e plasma i o n changes i n the o r i g i n a l s a l t w a t e r c h a l l e n g e , was r e l a t i v e l y u n a f f e c t e d by temperature i n c r e a s e alone, but had 100% m o r t a l i t y under c o n d i t i o n s of h i g h water s a l i n i t y and i n c r e a s e d temperature. The cumulative nature of s t r e s s had been shown by F l o s e t a l . (1988) wi t h g r a d i n g and t r a n s p o r t and a l s o by Barton e t a l . (1986) wi t h m u l t i p l e h a n d l i n g s . The f i v e low pH c h a l l e n g e s demonstrated t h a t exposure t o a c i d i c c o n d i t i o n s caused s i g n i f i c a n t p h y s i o l o g i c a l d i s t u r b a n c e s (hematocrit v a l u e i n c r e a s e and i o n l o s s ) which were most severe f o r s t o c k B and l e a s t severe f o r s t o c k E. In a l l t r i a l s t h a t showed s i g n i f i c a n t p h y s i o l o g i c a l change, f i s h i n s t o c k B c o n s i s t e n t l y had the l a r g e s t [ N a + ] p 1 and [ C l - J p ! l o s s e s . Stock E u s u a l l y d i s p l a y e d s m a l l e r l o s s e s i n [ N a + ] p 1 than o t h e r s t o c k s . Schom (1986), w i t h A t l a n t i c salmon, and Swarts e t a l . (1978), w i t h brook t r o u t , suggest t h a t the a b i l i t y of f i s h t o s u r v i v e low pH exposures i s b e t t e r i n f i s h from n a t i v e waters wi t h a low pH. Another 39 study w i t h brook t r o u t (Robinson e t a l . 1976) a l s o concluded t h a t a c i d t o l e r a n c e had a g e n e t i c component. The a v a i l a b l e r e c o r d s do not i n d i c a t e a n ything unique i n the watersheds or h a t c h e r i e s from which s t o c k s B and E o r i g i n a t e d . The probable mechanisms by which the changes i n h e m a t o c r i t v a l u e , [ N a + ] p l and [ C l ' J p ! o c c u r r e d have been reviewed by Fromm (1980) and McDonald (1983). Reduction i n [ N a + ] p i and [ C l ~ ] p ^ i n f i s h exposed t o a c i d waters have been shown t o happen as a r e s u l t of a decrease i n a c t i v e i o n uptake by i o n t r a n s p o r t e r s on the g i l l e p i t h e l i u m combined with an i n c r e a s e i n p a s s i v e i o n e f f l u x from the f i s h . I ncreases i n h e m a t o c r i t v a l u e have been observed i n rainbow t r o u t exposed t o pH 4.0 (Audet and Wood 1988; M i l l i g a n and Wood 1982). The l a t t e r study showed t h a t the i n c r e a s e d h e m a t o c r i t v a l u e was caused by a combination of lowered plasma volume, r e d c e l l s w e l l i n g and r e c r u i t m e n t of r e d c e l l s from the s p l e e n . The h i g h pH c h a l l e n g e s d i d not r e s u l t i n any s i g n i f i c a n t p h y s i o l o g i c a l changes w i t h i n s t o c k s or d i f f e r e n c e s between s t o c k s . The reasons f o r the absence of change under c h a l l e n g e c o n d i t i o n s may i n c l u d e combinations of the sampling time, a p p l i e d water pH, and the parameters measured. At pH v a l u e s above 9.54 the i n h i b i t i o n of ammonia exchange i s almost complete and ammonia l e v e l s w i l l i n c r e a s e 40 w i t h i n a few hours (Wright and Wood, 1985). Yesaki (1990) found t h a t rainbow t r o u t showed s i g n i f i c a n t [ N a + ] p 1 decreases a f t e r approximately 24 h a t pH 10. At pH va l u e s l e s s than 9.5, the l e n g t h of time f o r i o n l o s s e s t o occur i s g r e a t l y extended. I t i s necessary t o s t r e s s f i s h t o the p o i n t o f p h y s i o l o g i c a l d i s t u r b a n c e b e f o r e c o n c l u d i n g whether t h e r e are d i f f e r e n c e s between s t o c k s f o r a g i v e n c h a l l e n g e . Challenges a t h i g h e r pH f o r a longer time and use of parameters such as plasma ammonia c o n c e n t r a t i o n may be b e t t e r f o r c r e a t i n g and i l l u s t r a t i n g p h y s i o l o g i c a l d i s t u r b a n c e s . The t h r e e h a n d l i n g c h a l l e n g e s demonstrated t h a t t h e r e are s i g n i f i c a n t d i f f e r e n c e s among s t o c k s i n plasma glucose c o n c e n t r a t i o n response but not i n hema t o c r i t v a l u e s . Glucose i s c o n s i d e r e d t o be r e l i a b l e , and i s f r e q u e n t l y used, as an i n d i c a t o r o f s t r e s s (Mazeaud e t a l . 1977; Wedemeyer e t a l . 1990; Wedemeyer and McLeay 1981). Stock D showed the s m a l l e s t and s t o c k A the l a r g e s t g l u c o s e response t o the h a n d l i n g s t r e s s . V a r i a t i o n between w i l d and hatchery s t o c k s f o r b l o o d g l u c o s e c o n c e n t r a t i o n has been shown i n p r e v i o u s s t u d i e s u s i n g rainbow t r o u t (Wydoski e t a l . 1976; C a s i l l a and Smith 1977; Woodward and Strange 1987), largemouth bass (Williamson and Carmichael 1986) and Chinook salmon (Barton e t a l . 1986). R e f s t i e (1986) found t h a t 41 t h e r e was a g e n e t i c component t o s t r e s s induced g l u c o s e changes among d i f f e r e n t groups of a t l a n t i c salmon. The l a c k of h e m a t o c r i t v a l u e changes observed i n the t h r e e h a n d l i n g c h a l l e n g e s probably r e f l e c t s the sampling times used. The h e m a t o c r i t v a l u e changes observed by C a s i l l a and Smith (1977) were most dramatic i n the f i r s t 20 min a f t e r s t r e s s . Our f i r s t sample was not taken u n t i l 1 h (or 1.5 h) a f t e r h a n d l i n g . The plasma glucose c o n c e n t r a t i o n r e s u l t s showed t h a t t h e r e was a d i u r n a l v a r i a t i o n i n r e s t i n g l e v e l s . V a r i a t i o n i n r e s t i n g g l u c o s e c o n c e n t r a t i o n s has been shown by Congelton e t a l . (1984). In t h a t study, l e v e l s were low a t n i g h t and e l e v a t e d d u r i n g the day. Our s t u d i e s are c o n t r a d i c t o r y t o t h i s p a t t e r n but are i n agreement wi t h Barton e t a l . (1986) who showed d e c r e a s i n g l e v e l s as the day progressed. T h i s l a t t e r study a l s o showed a l a r g e r response to h a n d l i n g when f i s h were sampled l a t e i n the day. The thermal c h a l l e n g e r e v e a l e d no d i f f e r e n c e s between s t o c k s . The CTM f o r a l l s t o c k s was w i t h i n a narrow range, the upper l i m i t of which i s c l o s e t o the l e t h a l temperature t h a t P i p e r e t a l . (1982) r e p o r t f o r coho salmon. I t i s a l s o 0.7°C l e s s than a CTM p r e v i o u s l y r e p o r t e d (Becker and Genoway 1979) f o r coho salmon a c c l i m a t e d t o a s i m i l a r r e a r i n g temperature. There i s evidence f o r s t o c k and g e n e t i c d i f f e r e n c e s i n CTM f o r o t h e r s p e c i e s of f i s h . F i e l d s e t a l . (1987) found t h a t a Wisconsin s t o c k of largemouth bass had a s i g n i f i c a n t l y lower CTM than a F l o r i d a s t o c k . One e x p l a n a t i o n of the s i m i l a r i e s i n CTM i n our experiments may r e f l e c t the s m a l l geographic and l a t i t u d i n a l ranges i n v o l v e d as w e l l as the s i m i l a r h a b i t a t temperatures i n the l o c a t i o n s from which the s t o c k s o r i g i n a t e d . The weight and l e n g t h data confirmed r e p o r t e d d i f f e r e n c e s i n body conformation between c o a s t a l and i n l a n d s t o c k s of f i s h . At each of the 4 times t h a t weight and l e n g t h data were c o l l e c t e d , f i s h of s t o c k D were s i g n i f i c a n t l y l o n g e r than f i s h of equal weight from other s t o c k s . These c o n d i t i o n f a c t o r r e s u l t s are s i m i l a r t o those of T a y l o r and McPhail (1985a). They demonstrated t h a t i n l a n d s t o c k s tended t o be long and t h i n , w h i l e those from c o a s t a l l o c a t i o n s tended t o be s h o r t and deep bodied. They concluded t h a t these d i s t i n c t i o n s had a g e n e t i c b a s i s . In our groups of f i s h , s t o c k D was the o n l y one from an i n l a n d source. A more r e c e n t study (Swain and Holtby 1989) u s i n g two groups of coho salmon from w i t h i n a c l o s e geographic range but from d i f f e r e n t h a b i t a t s , demonstrated t h a t body morphology depended on h a b i t a t . Stream type f i s h had t h i n n e r bodies than the l a k e type. The methods they used l e f t open the p o s s i b i l i t y of d i f f e r e n c e s b e i n g 43 e n v i r o n m e n t a l l y induced, but o n l y i f they are f i x e d a f t e r a s h o r t i n d u c t i o n p e r i o d e a r l y i n l i f e . The r e s u l t s a l s o demonstrate t h a t t h e r e are body conformation changes over time. As salmon undergo the t r a n s i t i o n from p a r r t o smolt, t h e r e are a s e r i e s of mor p h o l o g i c a l changes t h a t occur, i n c l u d i n g a decrease i n c o n d i t i o n f a c t o r (Gorbman e t a l . 1982; Winans and N i s h i o k a 1987). Barton e t a l . (1985), u s i n g coho salmon, documented c o n d i t i o n f a c t o r decreases q u i t e s i m i l a r t o the changes we observed i n the c o a s t a l s t o c k s . The r e s u l t s showed t h a t t h e r e was a d i f f e r e n c e i n response t o s i m i l a r c h a l l e n g e s among r e a r i n g groups. During c h a l l e n g e s a t pH 3.65, r e a r i n g group 2 s t o c k s C and F had m o r t a l i t i e s , w h ile those from group 1 d i d not. At the same pH, group 2 stock E f i s h showed no r e d u c t i o n i n [Na +]p^ w h i l e those i n r e a r i n g group 1 d i d . In h a n d l i n g c h a l l e n g e s t h e r e was no d i f f e r e n c e i n r e s t i n g g l u c o s e l e v e l s but t h e r e was a d i f f e r e n c e i n the magnitude of the i n c r e a s e i n glucose c o n c e n t r a t i o n . F a c t o r s which can a l t e r g l u c o s e response i n c l u d e r e a r i n g temperature (Barton and Schreck 1987a), n u t r i t i o n a l s t a t u s (Barton e t a l . 1988) and s t o c k i n g d e n s i t y (Congelton e t a l . 1984). The c o l l e c t i o n o f c o n t r o l data f o r the many c h a l l e n g e s demonstrated f l u c t u a t i o n s i n r e s t i n g h e m a t o c r i t v a l u e and 44 [ N a + ] p 1 over time. As w i n t e r progressed, i o n l e v e l s i n c r e a s e d and h e m a t o c r i t v a l u e s decreased. T h i s t r e n d was r e v e r s e d as w i n t e r ended and s p r i n g progressed. A s m o l t i f i c a t i o n study i n coho salmon (Folmar and D i c k h o f f 1981), and work with rainbow t r o u t by Madsen and Naamansen (1989), document i n c r e a s e s i n [ N a + ] p 1 d u r i n g the months of March and A p r i l , decreases i n A p r i l or May f o l l o w e d by more i n c r e a s e s . The measurements i n our study show the same ge n e r a l t r e n d of i n c r e a s i n g plasma i o n c o n c e n t r a t i o n s d u r i n g the w i n t e r and s p r i n g . Challenge t e s t s have a wide v a r i e t y of a p p l i c a t i o n s and purposes (reviewed by Wedemeyer e t a l . 1990). As d i s c u s s e d by Schreck (1981), c h a l l e n g e s can be u s e f u l i n s e l e c t i n g genotypes t h a t are p h y s i o l o g i c a l l y b e s t s u i t e d t o t o l e r a t e s t r e s s . While the i n d i v i d u a l c h a l l e n g e t e s t r e s u l t s may r e v e a l some i n t e r e s t i n g and p o t e n t i a l l y important t r a i t s , the c h a l l e n g e s should a l s o be viewed i n combination ( F i g . 12). A p r o f i l e of v a r i o u s measurements was used by Buckley e t a l . (1985) t o assess the e f f e c t s of environmental d e g r a d a t i o n by comparing s t o c k s of largemouth bass. In t h a t study a number of i n d i c a t o r s of f i s h h e a l t h and c o n d i t i o n were measured i n c l u d i n g : swimming stamina; l i v e r weight and 45 F i g u r e 12. R e l a t i v e response p r o f i l e of s i x s t o c k s of coho salmon from southern B r i t i s h Columbia, Canada. The mean d i s t u r b a n c e experienced by each s t o c k ( r e l a t i v e t o o t h e r s t o c k s ) i n a s e l e c t i o n of c h a l l e n g e s was g i v e n a numeric v a l u e r a n g i n g from 1 (no e f f e c t ) t o 6 ( l a r g e e f f e c t ) . 46 molecular composition (DNA, RNA and p r o t e i n ) ; bone composition and s t r e n g t h ; and p a r a s i t i c i n f e s t a t i o n . They used the combination of parameters t o show d i f f e r e n c e s i n c o n d i t i o n and h e a l t h among p o p u l a t i o n s of f i s h . In a s i m i l a r way t h i s paper combines the r e s u l t s of c h a l l e n g i n g t e s t s t o show d i f f e r e n c e s among s t o c k s of f i s h . While one t e s t may not i n d i c a t e t h a t s t o c k s d i f f e r , a s e r i e s of t e s t s taken t o g e t h e r show t h a t each stock has a unique response p r o f i l e . The response p r o f i l e ( F i g . 12) was c o n s t r u c t e d by a s s i g n i n g a r e l a t i v e numerical v a l u e t o the o v e r a l l response of s t o c k s t o each type of c h a l l e n g e and shows t h a t s t o c k s are unique. Combining the r e s u l t s of the c h a l l e n g e t e s t s a l l o w s f o r an assessment of the r e l a t i v e performance c a p a c i t i e s of each s t o c k . When the combined responses t o the c h a l l e n g e t e s t s were compared, no i n d i v i d u a l s t o c k had a b e t t e r o v e r a l l performance than o t h e r s . The d i f f e r e n c e s among s t o c k s tended t o be c o n s i s t e n t w i t h i n c h a l l e n g e s but not between c h a l l e n g e s . For example the r a n k i n g w i t h i n the f i v e low pH c h a l l e n g e s showed t h a t s t o c k B had l a r g e r [ N a + ] p 1 l o s s e s than o t h e r s t o c k s . A l s o , the mean rank f o r st o c k B was s i g n i f i c a n t l y d i f f e r e n t from s t o c k s A and F. When a s i m i l a r comparison was done i n c l u d i n g a l l c h a l l e n g e s t h e r e were no s i g n i f i c a n t d i f f e r e n c e s among s t o c k s . T h i s suggests an 47 i n t e r a c t i o n between the response t o a c h a l l e n g e and s t o c k . In o t h e r words, the performance of a s t o c k i s dependent on the c h a l l e n g e a p p l i e d . A s u c c e s s f u l performance i n one c h a l l e n g e does not i n d i c a t e a b e t t e r o v e r a l l performance i n a l l c h a l l e n g e s (or a b e t t e r o v e r a l l f i t n e s s ) . The use of a number of s h o r t d u r a t i o n c h a l l e n g e t e s t s t o develop performance p r o f i l e s of s t o c k s of f i s h c o u l d make a v a l u a b l e c o n t r i b u t i o n t o the e x i s t i n g base of knowledge. R e s u l t s of t h i s type are p o t e n t i a l l y u s e f u l f o r : improving r e a r i n g and enhancement management; s e l e c t i n g s t o c k s f o r t r a n s p l a n t a t i o n or s e l e c t i o n and b r e e d i n g i n commercial a q u a c u l t u r e ; m o n i t o r i n g environmental d e g r a d a t i o n ; and f o r demonstrating the importance of management p o l i c i e s t h a t i n c l u d e the maintenance of s t o c k s . The t e s t procedures used and the measurements c o l l e c t e d i n t h i s study are r e l a t i v e l y simple and experiments of t h i s type are e a s i l y conducted. The r e t u r n of knowledge and understanding of s t o c k performance should outweigh the c o s t s of time, e f f o r t and equipment. To p r o v i d e a b e t t e r p r o f i l e , c h a l l e n g e s such as swimming performance, hypoxia and r e f e r e n c e t o x i c a n t s c o u l d be i n c l u d e d . I t i s important t o note t h a t when d e a l i n g w i t h the s e l e c t i o n of s t o c k s , the c h o i c e of c h a l l e n g e s w i l l depend on the g o a l s of the s e l e c t i o n program and environmental c o n d i t i o n s . 48 When the use of c h a l l e n g e s and the development of performance p r o f i l e s i s contemplated, i t i s important t o i d e n t i f y f a c t o r s which may a l t e r responses. For example, the i n f l u e n c e s of temperature, photoperiod, s m o l t i f i c a t i o n , stage of m a t u r i t y and r e a r i n g environment needs e l u c i d a t i o n . The r e s u l t s of the pr e s e n t study may have been i n f l u e n c e d by in n a t e d i f f e r e n c e s among st o c k s i n s m o l t i f i c a t i o n schedule or i n r e a c t i o n s t o d e c h l o r i n a t e d Vancouver water. R e p e t i t i o n o f c h a l l e n g e s i n d i f f e r e n t environments a t v a r i o u s times of year c o u l d make important c o n t r i b u t i o n s t o the understanding o f c h a l l e n g e t e s t responses. 49 C o n c l u s i o n s The experiments demonstrate t h a t c e r t a i n s t o c k s show d i s t i n c t responses t o c h a l l e n g e s . Stock B appeared t o possess a unique osmoregulatory t r a i t . T h i s was e v i d e n t i n s a l t water and low pH exposures. Stock D d i s p l a y e d minimal m e t a b o l i c response (as measured by plasma gl u c o s e c o n c e n t r a t i o n ) t o h a n d l i n g . The d e s i g n of the study l i m i t e d environmental d i f f e r e n c e s among s t o c k s making i t reasonable t o suggest t h a t the observed d i f f e r e n c e s had a g e n e t i c b a s i s . T h e r e f o r e , i t i s p o s s i b l e t h a t t h e r e are g e n e t i c d i f f e r e n c e s among s t o c k s of coho salmon t h a t r e s u l t i n d i f f e r e n t i a l response t o c h a l l e n g e t e s t s . Environment appeared t o i n f l u e n c e the response t o some of the c h a l l e n g e s . The t o l e r a n c e l i m i t s o f some s t o c k s i n low pH water d i f f e r e d between the two d i f f e r e n t r e a r i n g groups. There was a l s o a d i f f e r e n c e among r e a r i n g groups wit h r e s p e c t t o the magnitude of the glu c o s e response t o a h a n d l i n g s t r e s s . In the temperature t o l e r a n c e t e s t a l l f i s h reached t o l e r a n c e l i m i t s a t a s i m i l a r p o i n t . The c o n d i t i o n s used i n the h i g h pH c h a l l e n g e s d i d not r e s u l t i n any f i s h r e a c h i n g t h e i r t o l e r a n c e l i m i t s f o r the measured parameters. 50 There were a l s o o t h e r r e s u l t s t h a t were not r e l a t e d t o c h a l l e n g e t e s t s . D i f f e r e n c e s i n body conformation among st o c k s were observed, w i t h the i n l a n d s t o c k being l o n g e r than equal weight f i s h from c o a s t a l s t o c k s . There was a d i u r n a l v a r i a t i o n i n r e s t i n g g l u c o s e c o n c e n t r a t i o n s . A se a s o n a l v a r i a t i o n i n r e s t i n g plasma sodium i o n c o n c e n t r a t i o n was a l s o observed. 51 B i b l i o g r a p h y A l l e n d o r f , F.W. and S.R. Phelps. 1980. Loss of G e n e t i c V a r i a t i o n i n a Hatchery Stock of C u t t h r o a t T r o u t . Trans. Am. F i s h . S o c , 109: 537-543. A l l e n d o r f , F.W. and F.M. U t t e r . 1979. 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Ge n e t i c estimates of stock compositions of 1983 chinook salmon, Oncorhynchus tshawtyscha, h a r v e s t s of the Washington c o a s t and the Columbia R i v e r . F i s h e r y B u l l e t i n : V o l . 85, No. 1, 13-23. Wedemeyer, G.A. 1976. P h y s i o l o g i c a l response of j u v e n i l e coho salmon Oncorhynchus kisutch and rainbow t r o u t Salmo gairdneri t o h a n d l i n g and crowding s t r e s s i n i n t e n s i v e f i s h c u l t u r e . J . F i s h . Res. Bd. Can. 33: 2699-2702 Wedemeyer, G.A., B.A. Barton and D.J. McLeay. 1990. S t r e s s and a c c l i m a t i o n . Chap. 14 i n Methods i n F i s h B i o l o g y , C.B. Schreck and P.B. Moyle Ed. American F i s h e r i e s S o c i e t y , Bethesda Maryland, U.S.A. i n p r e s s . Wedemeyer, G.A. and D.J. McLeay. 1981. Methods f o r determ i n i n g the t o l e r a n c e o f f i s h e s t o environmental s t r e s s o r s , pages 247-268 i n A.D. P i c k e r i n g , e d i t o r . S t r e s s and F i s h . Academic Press, London, England, p. 247-275 Wedemeyer, G.A., D.J. McLeay, and C P . Goodyear. 1984. A s s e s s i n g the t o l e r a n c e of f i s h and f i s h p o p u l a t i o n s t o environmental s t r e s s : the problems and methods of mo n i t o r i n g , pages 163-195 i n V.W. C a i r n s , P.B. Hodson, and J.O. Nriagu, Eds. Contaminant e f f e c t s on f i s h e r i e s , John Wiley and Sons, Toronto, Canada. Wehrhahn, C F . and R. Powell. 1987. E l e c t r o p h o r e t i c v a r i a t i o n , r e g i o n a l d i f f e r e n c e s , and gene flow i n the coho salmon (Oncorhynchus kisutch) of southern B r i t i s h Columbia. Can. J . F i s h . Aquat. S c i . 44: 822-831. 62 Whelen, M.A., and Olmsted, W.R. 1982. 1981 b i o p h y s i c a l s t u d i e s of s e l e c t e d Chinook (Oncorhynchus tshawytscha) and Coho (0. kisutch) salmon producing t r i b u t a r i e s of the south Thompson R i v e r drainage. P a r t I I - a d u l t salmon i n v e s t i g a t i o n s . E.V.S. C o n s u l t a n t s L t d . North Vancouver B.C. pp. 25-50. W i l k i n s o n , L. 1988. S y s t a t : the system f o r s t a t i s t i c s . S y s t a t Inc. Evanston, I I . , USA. 822pg. Wi l l i a m s o n , J.H. and G.J. Carmichael. 1986. D i f f e r e n t i a l response of h a n d l i n g s t r e s s by F l o r i d a , n o r t h e r n , and h y b r i d largemouth bass. Trans. Am. F i s h . Soc. 115:756-761. Wilmot, R.L. and C.V. Burger. 1985. G e n e t i c d i f f e r e n c e s among p o p u l a t i o n s of Alaskan sockeye salmon. Trans. Am. F i s h . Soc. 114: 236-243. Winans, G.A. and R.S. N i s h i o k a . 1987. A m u l t i v a r i a t e d e s c r i p t i o n o f change i n body shape of coho salmon (Oncorhynchus kisutch) d u r i n g s m o l t i f i c a t i o n . Aquaculture 66: 235-245 W i t h l e r , R.E., 1988. Genetic consequences of f e r t i l i z i n g chinook salmon (Oncorhynchus tshawytscha) eggs wi t h pooled m i l t . Aquaculture, 68: 15-25. W i t h l e r , R.E., W.C. C l a r k e , B.E. R i d d e l l , and H. K r e i b e r g . 1987. G e n e t i c v a r i a t i o n i n freshwater s u r v i v a l and growth of chinook salmon (Oncorhynchus tshawytscha). Aquaculture 64: 85-96. Woodward, C C . and R.J. Strange. 1987. P h y s i o l o g i c a l s t r e s s responses i n w i l d and h a t c h e r y - r e a r e d rainbow t r o u t . Trans. Am. F i s h . Soc. 116: 574-579. 63 Wright, P.A. and CM. Wood. 1985. An a n a l y s i s o f b r a n c h i a l ammonia e x c r e t i o n i n the freshwater rainbow t r o u t : e f f e c t s of environmental pH change and sodium uptake blockade. J . Exp. B i o l . 114: 329-353. Wydoski, R.S., G.A. Wedemeyer and N.C Nelson. 1976. P h y s i o l o g i c a l response of hooking s t r e s s i n hatchery and w i l d rainbow t r o u t (Salmo gairdneri). Trans. Am. F i s h . Soc. 5: 601-606. Y e s a k i , T.Y. 1990. The s u r v i v a l and p h y s i o l o g y o f rainbow t r o u t (Oncorhynchus mykiss) i n a l k a l i n e hard water. M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia. Zar, J.H. 1984. B i o s t a t i s t i c a l A n a l y s i s . P r e n t i c e - H a l l Inc. Englewood C l i f f s , NJ., USA. 717pg. 64 Appendices / 65 Appendix A Mean and standard e r r o r of each parameter measured, by s t o c k and water c o n d i t i o n f o r each of the c h a l l e n g e t e s t s . 66 Appendix A, T a b l e I . Means, by st o c k and treatment, f o r the parameters measured i n s a l t w a t e r c h a l l e n g e 1 and 2 (the temperature i n c r e a s e p l u s s a l i n e c h a l l e n g e ) . Standard e r r o r s are i n s u b s c r i p t . Stock A B C D E F Sal t w a t e r C h a l l e n g e 1 Wt change, c o n t r o l -0.6 -0.7 -0.7 -0.6 -0.8 -0.8 s a l t w a t e r -0.9 -1.0 -1.3 -1.4 -1.2 -1.2 Hematocrit, c o n t r o l 4 9 1.5 52 1.6 5 3 1.2 5 4 1.8 5 4 1.5 51 1.5 s a l t w a t e r 4 7 1.3 43a L 1 4 6 a1.2 4 4 a0.9 4 8 1.3 4 6 1.1 [ C l ' J p ! , c o n t r o l 1 3 1 1.3 12 9 1.5 I 3 7 4.1 133 2.4 131 2.0 132 2.5 s a l t w a t e r 1 6° a2.2 166 a 4 - 7 1 6 2 35.9 l8°a5.3 l 7 3 a5.0 16933.7 [ N a + ] p i , see F i g u r e 3 Sa l t w a t e r C h a l l e n g e 2 M o r t a l i t i e s c o n t r o l 0 0 0 0 0 0 temp i n c r . 0 0 0 0 0 0 temp+salt 30 60 100 100 80 30 Hematocrit c o n t r o l 4 4 1.2 4 7 l . l 4 8 1.0 4 6 1.2 5 0 1.2 4 4 1.2 temp i n c r . 4 9 1.3 4 5 1.4 5 4 1.7 52a0.8 4 9 1.3 5530.8 temp+salt 4Ob1.6 4 7 1.4 43a2.0 4 4 Ci . o [ C l ~ ] p i , c o n t r o l 133 1.6 132 L 7 I 3 8 3.0 126 1.3 125 2.4 I 3 8 3.0 temp i n c r . I 4 9 6.0 I 4 4 2.4 l 4 l l 3 . 0 I 3 7 2.0 128 L 1 I 4 0 2.3 temp+salt 1 8 9 b 7 7 l7°b5.5 l 9 6 b6.5 l 76 b 5.5 [ N a + ] p i , see f i g u r e 4 a Challenge mean shows s i g n i f i c a n t change from c o n t r o l mean. b S i g n i f i c a n t change both from c o n t r o l and temperature i n c r e a s e . c I n d i c a t e s s i g n i f i c a n t change from temperature i n c r e a s e o n l y . Weight i n grams; hem a t o c r i t as %; [ N a + ] p 1 and [ C l - ^ ! as mEq*L~ 67 Appendix A, Ta b l e I I . Means, by stock and treatment, f o r the parameters low pH c h a l l e n g e s . Standard e r r o r s are i n s u b s c r i p t . Stock A B C D E F Low pH Chal l e n g e 1 Wt. change, c o n t r o l -0.1 -0.4 -0.5 -0.3 -0.9 -0.4 low pH -0.1 +0.9 +0.1 0.0 +0.3 +0.2 Hematocrit, c o n t r o l 4 4 1.3 4 7 1.1 4 8 1.0 4 6 1.2 50 1.2 4 4 1.2 low pH 5 8 3 1 . 4 5 9 3 1 . 4 6 ° a 2 . 0 6 ° a i.3 5 9 90.8 5? ai.2 [ C l ~ ] p l / c o n t r o l 1 3 3 1.6 I 3 2 1.7 1 3 8 3.0 1 2 6 1.3 1 2 5 2.4 1 3 8 3.0 low pH i o i a 4 < 9 8 2 a 6 . 1 101a5.8 l°5a5.7 9 4 d 1.5 9° a3 . 4 [ N a + ] p 1 , see F i g u r e 5A Low pH Chal l e n g e 2 Hematocrit, c o n t r o l 4 5 1.4 4 2 1.7 4 6 0.8 4 4 1.3 4 5 1.2 4 4 2.2 low pH 6 5 3 2.5 62ao.9 6 9 3 1 . 4 5 9 a i.9 5 4 2.7 5 9 a5.0 [ N a + ] p l , c o n t r o l 1 4 5 2.6 1 3 6 3.2 1 3 9 2.7 138 L 4 I 3 8 2.5 1 3 9 1.4 low pH I 3 3 2.7 122 L 7 I 3 2 3.7 128 4 > 9 1 3 0 3.8 130 5 - 7 Low pH Chal l e n g e 3 % M o r t a l i t y , c o n t r o l 0 0 0 0 0 0 low pH 0 0 50 0 0 18 Hematocrit, c o n t r o l 4 2 l . l 4 3 0.9 4 0 0.8 4 ° 1.1 3 9 1.1 4 0 1.7 low pH 6 2 a i . 3 6 l 3 1 . 4 5 9 3 2.7 5 4 3 1 . 2 5 5 a L 3 60a4.3 [ N a + ] p 1 , see F i g u r e 5B Low pH Cha l l e n g e 4 Hematocrit, c o n t r o l 4 5 1.4 4 2 1.7 4 6 0.8 4 4 1.3 4 * 1.2 4 4 2.2 low pH 5 3 1.2 5 5 a i . 2 5 5 3 1.5 5 3 3 1.3 4 8 2.6 5 0 2.0 [ N a + ] p i , c o n t r o l 1 4 5 2.6 I 3 6 3.2 I 3 9 2.7 138 L 4 I 3 8 2.5 I 3 9 1.4 low pH 1 4 0 2.2 1 3 6 2.7 1 3 6 2.7 1 3 5 2.6 1 3 7 2.0 1 4 5 1.7 Low pH Cha l l e n g e 5 Hematocrit, c o n t r o l 4 2 l . l 4 3 0.9 4 0 0.8 4 ° l . l 3 9 1.1 4 0 1.7 low pH 4 9 9 1 . 4 5Oa0.9 4 6 3 1 . 1 4 3 1.7 4 3 1.8 4 9 3 1 . 4 [ N a + ] p i , c o n t r o l 152 L 4 I 5 1 1.2 151 0.7 1 4 6 1.0 I 4 8 1.2 I 4 7 1.5 low pH 1 4 1 3 0 . 6 1 4 3 a L 1 l 4 2 a L 3 1 4 2 1.0 I 4 5 2.5 1 4 1 1.9 a Challenge mean shows s i g n i f i c a n t change from c o n t r o l mean. Weight i n grams; hema t o c r i t as-%; [ N a + ] p l and [ C l ~ ] p l as mEq-L 68 Appendix A, T a b l e I I I . Means, by st o c k and treatment, f o r the parameters measured i n h i g h pH c h a l l e n g e s . Standard e r r o r s are i n s u b s c r i p t . Stock A B C • D E F High pH Cha l l e n g e 1 Hematocrit, c o n t r o l 45 1.4 45 1.8 40 2.9 42 1.8 46 2.2 49 1.9 h i g h pH 45 2.3 46 1.1 49 1.2 46 3.0 44 0.9 46 1.8 [ C l ' l p ! , c o n t r o l 124 1.8 122 0.9 122 1.9 128 1.8 124 2.2 I 2 2 1.5 h i g h pH 127 2.3 130 1.9 128 1.1 126 2.0 130 5.3 l 32 a2.4 [ N a + ] p 1 , c o n t r o l 150 2.3 153 1.4 146 1.9 149 0 > 7 145 2.2 148 L 4 h i g h pH 148 2.2 1 4 ° a 0 . 9 136 a 1.2 139 a 2.8 140 1.6 141 1.8 High pH Cha l l e n g e 2 Hematocrit, c o n t r o l 34 1.3 35 0.8 34 1.2 36 1.2 38 1.5 42 i . 6 h i g h pH 41 2.4 4 3 a L 2 44 a 2.9 40 3.2 40 2.1 46 0.4 [ C l ~ ] p i , c o n t r o l 130 1.5 128 1.9 130 1.4 130 1.1 130 1.8 I 3 0 1.5 hi g h pH 131 1.3 130 0.5 132 1.3 129 1.6 129 1.2 127 1.5 [ N a + ] p 1 , see F i g u r e 6 High pH Cha l l e n g e 3 Hematocrit, c o n t r o l 42 1.3 41 1.8 45 1.9 38 1'.4 44 2.0 47 3.2 hi g h pH 38 2.1 45 1.6 45 2.1 40 1.0 42 1.8 48 i j [ C l ~ ] p l , c o n t r o l 137 3.3 130 3.3 137 2.4 134 1.9 137 2.4 137 2. 9 h i g h pH 144 1.6 133 2.3 133 3.6 122 1.7 131 1.3 138 2.1 [ N a + ] p 1 , c o n t r o l 156 1.5 150 1.5 149 1.5 150 3.2 140 2.5 143 2.4 h i g h pH 136 a 1.3 152 2.0 147 2.5 160 3.5 138 3.1 150 1 > 4 a Challenge mean shows s i g n i f i c a n t change from c o n t r o l mean. Weight i n grams; hem a t o c r i t as %; [ N a + ] p l and [ C l ~ ] p i as mEq'L 69 Appendix A, T a b l e IV. Means, by s t o c k and treatment, f o r the parameters measured i n h a n d l i n g c h a l l e n g e s . Standard e r r o r s are i n s u b s c r i p t . Stock A B C D E F H a n d l i n g C h a l l e n g e l Hematocrit, 0 h 50 1.8 46 0.8 47 2.1 47 2.2 48 1.7 49 8.1 1 h 53 1.9 44 1.4 46 1.5 48 2.0 51 1.3 51 1.2 3 h 47 2.6 46 2.0 49 1.2 45 1.4 47 1.4 45 1.3 6 h 49 1.4 48 0.8 48 1.5 48 2.4 48 2.3 47 1.5 9 h 50 1.9 48 1.3 49 1.9 49 0.8 50 1.0 53 0.9 12 h 51 1.3 50 1.9 51 1.4 51 2.5 51 1.4 54 1.6 18 h 51 2.2 51 1.5 50 1.1 49 1.5 50 1.3 53 1.8 Plasma Glucose, see F i g u r e 8A Handling C h a l l e n g e 2 Hematocrit, 0 h 53 1.2 51 1.2 50 1.3 52 2.4 49 1.5 49 2.2 1.5 h 53 1.3 47 1.4 51 1.1 49 2.1 51 2.2 54 2.0 3 h 56 1.7 53 0.9 53 1.5 50 2.2 46 2.2 51 2.1 6 h 50 1.7 50 1.3 52 1.4 49 2.1 55 1.6 50 1.1 9 h 56 1.8 56 1.2 52 1.2 48 1.8 49 1.5 50 1.8 12 h 55 1.0 52 1.3 55 1.5 50 1.4 53 2.5 53 1.8 18 h 56 1.9 53 1.5 56 a 1.6 53 1.8 50 2.2 49 1.7 Smolt Index 3.93 3.97 4.00 4.00 3.93 3.97 Plasma Glucose, see F i g u r e 8B H a n d l i n g C h a l l e n g e 3 Hematocrit, 0 h 52 1.1 48 0.9 51 1.1 46 1.5 50 2.1 52 1.3 1 h 49 2.3 50 0.8 46 1.1 47 1.1 51 2.2 49 1.5 3 h 51 1.6 49 1.2 47 0.8 48 1.5 49 1.7 51 0.9 6 h 54 1.4 50 1.6 46 1.3 48 2.0 54 1.7 50 1.1 9 h 51 2.8 54 a i 1.4 46 2.3 47 1.3 48 1.3 53 1.7 12 h 57 2.2 49 0.7 49 1.5 49 1.6 50 1.3 52 1.9 18 h 52 0.9 54 a i 2.1 54 1.7 50 1.4 50 0.6 54 1.5 Smolt Index, 3. .40 3 .93 3. 93 4. 00 3. ,90 3 .93 Plasma Glucose, see F i g u r e 8C  Mean shows s i g n i f i c a n t change from 0 h mean f o r t h a t s t o c k . Hematocrit i s as a %; Smolt Index i s a r e l a t i v e measure. 70 Appendix B D e s c r i p t i o n of h a t c h e r i e s and l o c a l watersheds from which the s i x s t o c k s o r i g i n a t e d . 71 Appendix B, T a b l e I . Summary of the i n f o r m a t i o n t h a t was a v a i l a b l e on each of the h a t c h e r i e s from which s t o c k s i n the s i x s t o c k comparison o r i g i n a t e d from. Stock A B C D E F 1s t year of o p e r a t i o n 1971 1982 1980 1982 1974 1981 Generations enhanced 5 1 2 1 4 1 K i l o m e t e r s t o ocean approx 5 approx 100 approx. 100 approx. 500 approx 5 approx 25 Release age (year) 1 1 1 0 1 1 Return age (year) 3 3 3 3 3 3 Spawning months June -Dec. Sept -Apr. Oct.-Mar. Oct.-Dec. Oct.-Nov. Sept.-Mar. Re a r i n g temp (°C) 1-14 2-22 4-18 7-8 1-12 7 Water source r i v e r + ground r i v e r + ground r i v e r + ground ground water r i v e r + ground ground water R i v e r temp (°C) 2-16 2-23 0-18 2-23 0-22 NA Ground-water temp 8 5-12 11 7-8 7-11 7 R i v e r water pH 6.4-6.8 5.6-6.7 7.1-7.4 6.9-7.9 6.8-7.9 6.6-7.5 Ground-water pH approx 7 6-7 7.7-8.4 6.4-9.7 NA 6.9-7.2 R i v e r Hardness * 4-6 7-11 13-27 17-28 15-36 22-25 Groundwater Hardness * approx. 20 10-13 53-86 36-93 40-49 29-52 * hardness = CaC0 3 mg/L 72 CAPILANO COHO Hatchery i n f o r m a t i o n P r o d u c t i o n area: B u r r a r d I n l e t (area 28) F i r s t year of o p e r a t i o n - 1971 D i s t a n c e from S t r a i t of Georgia - approx. 5 Km Water source: S u r f a c e water i s mixed w i t h groundwater. Water temp a t hatchery: range from l t o 1 4O C . Water temp ( r i v e r ) : Ranges from 1 t o 14°C. Water temp (groundwater): 8°C pH range ( r i v e r ) : 6.4 - 6.8 pH range (ground water) approx. 7 Hardness range ( r i v e r ) 4 - 6 ( s o f t ) Hardness range (ground water) approx. 20 Disease agents and p a r a s t i e s : F u r u n c u l o s i s , BKD, and ceratomyxasis and u n i d e n t i f i e d . Release/enhancement s t r a t e g y : Spawners are r e c r u i t e d from the C a p i l a n o R i v e r , eggs are incubated and f r y r e a r e d a t the hatchery f a c i l i t y . Coho are r e l e a s e d a f t e r 1 year. Some f r y (0 age) are p l a n t e d above the hatchery i n the C a p i l a n o r e s e r v i o r . In the p a s t , some Coho have been r e a r e d i n sea pens i n Indian Arm and S e c h e l t I n l e t then r e l e a s e d from t h e r e . R e t u r n i n g A d u l t s : The Coho run begins i n June and ends i n December. The peak of the run v a r i e s depending on the year. The r i v e r i s s u b j e c t t o p e r i o d s of low flow and o f t e n mature f i s h can spend a p e r i o d of time a t the mouth of the r i v e r . Spawning a t the hatchery takes p l a c e once a month. The age o f the r e t u r n i n g a d u l t s i s 3 y e a r s . H a b i t a t : The hatchery has almost r e p l a c e d the n a t u r a l coho run. Water s t o r a g e , flow r e g u l a t i o n and r i v e r c h a n n e l i n g have had a s e r i o u s e f f e c t on m i g r a t i o n upstream and spawning h a b i t a t . 73 CHEHALIS COHO Hatchery i n f o r m a t i o n P r o d u c t i o n area: Lower F r a s e r (area 29) F i r s t year of o p e r a t i o n - 1982 D i s t a n c e from S t r a i t of Georgia - approx 95 km Water source: A combination of s u r f a c e ( C h e h a l i s R.) and groundwater (3 w e l l s ) are used. I n c u b a t i o n i s on groundwater and r e a r i n g i s mostly on r i v e r water. As the temperature of the r i v e r r i s e s d u r i n g the s p r i n g , more and more of i t i s added t o the hatchery water supply. During the summer, groundwater i s added o n l y when warm r i v e r water begins t o cause h e a l t h problems. Water temp a t hatchery: Temperature ranges from 1-23°C. Water temp ( r i v e r ) : 1 - 23°C Water temp (groundwater): 5 - 12°C pH range ( r i v e r ) : 5.6 - 6.7 pH range (ground water): 6 - 7 Hardness range ( r i v e r ) : 7 - 1 1 Hardness range (ground water): 1 0 - 1 3 Disease agents and p a r a s t i e s : PKD, Henneguya, Ceratomyxosis and u n i d e n t i f i e d . Release/enhancement s t r a t e g y : In the p a s t , a d u l t s were r e c r u i t e d from a number of areas i n the watershed (eg. Coho Creek, B i g S i l v e r Creek, Squakum Creek, H i c k s Creek, and H a r r i s o n R i v e r ) . Each of these groups of f i s h were r e a r e d s e p e r a t e l y and then r e t u r n e d t o t h e i r n a t i v e a r e a . Now, a l l r e l e a s e s are from the hatchery i t s e l f . These r e l e a s e d coho are 1 year o l d smolts. R e t u r n i n g A d u l t s : The coho run begins i n September and runs u n t i l A p r i l . The age of the r e t u r n i n g a d u l t s i s 3 y e a r s . H a b i t a t : A l l f i s h t h a t use the F r a s e r R i v e r f o r m i g r a t i o n are s u b j e c t t o the e f f e c t s of i n d u s t r i a l waste dumping, sewage d i s c h a r g e , urban development, r a i l w a y and highway c o n s t r u c t i o n , f o r e s t r y , a g r i c u l t u r e , mining, and h y d r o e l e c t r i c g e n e r a t i o n . The changes t o water flow, water q u a l i t y and j u v e n i l e h a b i t a t probably have a cumulative e f f e c t on the s u r v i v a l of j u v e n i l e s and m i g r a t i n g smolts. Logging a c t i v i t i e s have r e s u l t e d i n f l o o d i n g , s c o u r i n g and s i l t a t i o n . These r e s u l t s have had an e f f e c t on h a b i t a t . 74 CHILLIWACK COHO Hatchery i n f o r m a t i o n P r o d u c t i o n area: Lower F r a s e r (area 29) F i r s t year of o p e r a t i o n - 1980 Dist a n c e from S t r a i t of Georgia - approx 100 km. Water source: A mixture of C h i l l i w a c k R i v e r water and groundwater (2 w e l l s ) i s used. The primary water source i s the r i v e r . Groundwater i s added when the temperature gets below 4°C. Water temp a t hatchery: The temperature range i s 0-18°C Water temp ( r i v e r ) : 0 - 18°C Water temp (groundwater): 11°C pH range ( r i v e r ) : 7.1 - 7.7 pH range (ground water): 7.7 - 8.4 Hardness range ( r i v e r ) : 13 - 27 Hardness range (ground water): 53 - 86 Disease agents and p a r a s i t e s : F u r u n c u l o s i s , ceratomyxosis, Henneguya, PKD, BKD and u n i d e n t i f i e d . Release/enhancement s t r a t e g y : In the p a s t , spawning f i s h were r e c r u i t e d from the v a r i o u s areas along the C h i l l i w a c k R i v e r and i t s t r i b u t a r i e s . The j u v e n i l e s were r e l e a s e d as e i t h e r f r y (0 age) o r smolts (1+ age) i n t h e i r n a t i v e streams. More and more, a l l r e c r u i t m e n t and r e l e a s e s (always smolts now) are from the hatchery. R e t u r n i n g A d u l t s : The coho run begins i n October and ends i n the month of March. The age of r e t u r n i n g a d u l t s i s 3 y e a r s . H a b i t a t : A l l f i s h t h a t use the F r a s e r R i v e r f o r m i g r a t i o n are s u b j e c t t o the e f f e c t s of i n d u s t r i a l waste dumping, sewage d i s c h a r g e , urban development, r a i l w a y and highway c o n s t r u c t i o n , f o r e s t r y , a g r i c u l t u r e , mining, and h y d r o e l e c t r i c g e n e r a t i o n . The changes t o water flow, water q u a l i t y and j u v e n i l e h a b i t a t probably have a cumulative e f f e c t on the s u r v i v a l of j u v e n i l e s and m i g r a t i n g smolts. Logging a c t i v i t i e s have r e s u l t e d i n f l o o d i n g , s c o u r i n g and s i l t a t i o n . These r e s u l t s have had an e f f e c t on h a b i t a t . Channeling and dyking, a g r i c u l t u r a l a c t i v i t y and urban development have a f f e c t e d r e a r i n g h a b i t a t . 75 EAGLE COHO Hatchery i n f o r m a t i o n P r o d u c t i o n a r e a : South Thompson (area 29) F i r s t year of o p e r a t i o n - 1983 Dis t a n c e from S t r a i t o f Georgia - approx. 500 km. Water source: Only groundwater i s used (2 w e l l s ) Water temp a t hatchery: 7 - 8°C Water temp ( r i v e r ) : 2 - 23°C Water temp (groundwater): 7 - 8°C pH range ( r i v e r ) : 6.9 - 7.9 pH range (ground water): 6.4 - 9.7 Hardness range ( r i v e r ) : 1 7 - 2 8 Hardness range (ground water): 3 6 - 9 3 Disease agents and p a r a s i t e s : Some d i s e a s e s have o c c u r r e d but remain u n i d e n t i f i e d . Few samples have been taken. Release/enhancement s t r a t e g y : A d u l t s are taken from both the Eagle R i v e r and Salmon R i v e r systems. J u v e n i l e s are r e l e a s e d t o the system of o r i g i n as f r y (0+ age). A ve r y s m a l l percentage o f f i s h are h e l d over f o r l a t e r r e l e a s e R e t u r n i n g A d u l t s : The coho run begins i n October and ends i n December. The age of r e t u r n i n g a d u l t s coho i s mostly 3 y e a r s . H a b i t a t : A l l f i s h t h a t use the F r a s e r R i v e r f o r m i g r a t i o n are s u b j e c t t o the e f f e c t s of i n d u s t r i a l waste dumping, sewage d i s c h a r g e , urban development, r a i l w a y and highway c o n s t r u c t i o n , f o r e s t r y , a g r i c u l t u r e , mining, and h y d r o e l e c t r i c g e n e r a t i o n . The changes t o water flow, water q u a l i t y and j u v e n i l e h a b i t a t probably have a cumulative e f f e c t on the s u r v i v a l o f j u v e n i l e s and m i g r a t i n g smolts. The South Thompson system i s c h a r a c t e r i z e d by a system of l a r g e l a k e s (eg Shuswap L . ) . T h i s tends towards p r o d u c t i v e h a b i t a t s w i t h s t a b l e flow. I r r i g a t i o n o f a g r i c u l t u r a l lands and h y d r o e l e c t r i c dams have had a moderate impact on r e a r i n g h a b i t a t . 76 QUINSAM COHO Hatchery i n f o r m a t i o n P r o d u c t i o n a r e a : mid Vancouver I s . (area 13) F i r s t year of o p e r a t i o n - 1974 Dis t a n c e from S t r a i t o f Georgia - 5 km Water source: Surface water from the Quinsam R i v e r i s mixed w i t h groundwater ( s p r i n g source) from C o l d Creek. Water temp a t hatchery: I n c u b a t i o n temperatures vary from 1 t o 8°C ( r i v e r water). Rearing water ( s p r i n g ) temperature ranges from 8 t o 12°C. Water temp ( r i v e r ) : 0 - 16°C Water temp, (groundwater): 8 - 12°C pH range ( r i v e r ) : 6.8 - 7.9 pH range (ground water) NA Hardness range ( r i v e r ) : 15 - 36 Hardness range (ground water): 40 - 49 Disease agents and p a r a s t i e s : F u r u n c u l o s i s , BKD, Henneguya and u n i d e n t i f i e d . Release/enhancement s t r a t e g y : Eggs and m i l t are taken from spawning a d u l t s t h a t r e t u r n t o the hatchery. The m a j o r i t y o f j u v e n i l e s are r e l e a s e d from the hatchery as smolts (1+ age). F r y are a l s o p l a n t e d t o water systems above the hatchery i n the f a l l of t h e i r f i r s t year. The numbers of j u v e n i l e s r e l e a s e d i n t h i s way v a r i e s from year t o year. R e t u r n i n g A d u l t s : The coho run s t a r t s i n l a t e September and ends i n e a r l y December. The age of r e t u r n i n g a d u l t s i s 3 y e a r s . W i l d H a b i t a t : Mostly s m a l l streams s u b j e c t t o low summer flow. Logging o p e r a t i o n s ( l o g storage and s o r t i n g ) has had a moderate impact. The e f f e c t s of upstream mining a c t i v i t i e s has been a l e v i a t e d s i n c e the e a r l y 80s. H y d r o e l e c t r i c dams have r e s u l t e d i n l o s s of spawning areas but flows are s t a b l e . 77 TENDERFOOT COHO Hatchery i n f o r m a t i o n P r o d u c t i o n area: Howe Sound (Area 28) Sguamish Hatchery o p e r a t i o n b e g i n s : 1981 Enhancing Coho s i n c e : 1982 d i s t a n c e from S t r a i t o f Georgia - 26 km Water source: A l l water i s from w e l l s ( 3 ) . Water temp a t hatchery: 7°C Water temp ( r i v e r ) : NA Water temp (groundwater): 7°C pH range ( r i v e r ) : 6.6 - 7.5 pH range (ground water): 6.9 - 7.2 Hardness range ( r i v e r ) : 22 - 25 Hardness range (ground water): 29 - 52 Disease agents and p a r a s t i e s : None r e p o r t e d , although a few cases of u n i d e n t i f i e d d i s e a s e s have o c c u r r e d . F u r u n c l u o s i s has been i s o l a t e d from w i l d f i s h i n the area. Release/enhancement s t r a t e g y : The a d u l t coho are r e c r u i t e d from Tenderfoot Creek, Squamish R i v e r , Cheakamus R i v e r , A s h l u R i v e r and oth e r nearby water systems as w e l l as from r e t u r n s t o the hatchery. J u v e n i l e s are r e l e a s e d t o t h e i r streams of o r i g i n and d i r e c t l y from the hatchery. Release i s as smolts (1+ age). R e t u r n i n g A d u l t s : The coho run begins i n September and ends i n March. The age of r e t u r n i n g a d u l t s i s 3 y e a r s . W i l d H a b i t a t : The c o a s t a l r i v e r s are s u b j e c t t o l a r g e f l u c t u a t i o n s i n flow. Flow i s h i g h e s t d u r i n g the summer f r e s h e t and wint e r f l o o d i n g i s common. Sedimentation and s c o u r i n g are common problems i n many r i v e r s . Logging a c t i v i t i e s accentuate these problems. P o r t development has a f f e c t e d e s t u a r y h a b i t a t . 78 Reference Sources As much i n f o r m a t i o n as p o s s i b l e was gleaned from a number of d i f f e r e n t sources i n c l u d i n g : Blackmum e t a l . (1985); Department of F i s h e r i e s and Oceans, (1988); MacKinlay, (1984); M i l l e r e t a l . (1986); and Whelen and Olmsted, (1982). D e t a i l s of each of the s i x s t o c k s came through p e r s o n a l communications with; Buck, P., C h i l l i w a c k R i v e r Hatchery; H a r r s i o n , C , Eagle R i v e r Hatchery; K a h l , L., C h e h a l i s R i v e r Hatchery; stone, E., C a p i l a n o R i v e r Hatchery; Thompson, B., Tenderfoot Hatchery; and V a n t i n e , J . , Quinsam R i v e r Hatchery. 79 Appendix C D e t a i l s on the egg c o l l e c t i o n and h a t c h i n g as w e l l as dates f o r sample weighing and c h a l l e n g e s . 80 Appendix C, T a b l e I . D e t a i l s on c o l l e c t i o n and h a t c h i n g o f each of the s t o c k s used i n the s i x stock comparison. Information i n c l u d e s from spawning a t the d i f f e r e n t h a t c h e r i e s t o ponding a t UBC (or h a t c h e r y ) . Stock A B C D E F Spawning date 14/12 1987 20/01 1988 12/18 1987 18/11 1987 27/11 1987 24/12 1987 Pool s i z e (# parent) 6 f . 6 m. 25 f . 25 m. 15-20 f . 15-20 m. NA 100 f . 100 m. 12 f . 12 m. A r r i v a l UBC 04/03 1988 09/03 1988 01/03 1988 28/06 1988 05/03 1988 04/03 1988 L i f e stage a t a r r i v a l eyed egg eyed egg eyed egg f r y * (3.7 g) eyed egg eyed egg A r r i v e ATU 295 334 357 NA * 378 490 Hatching date 22/03 -29/03 29/03 -03/04 18/03 -23/03 17/01 -18/01* 11/03 -16/03 03/03 -07/03 Hatch ATU 450 500 485 450* 440 500 Ponding date 23/04 24/04 12/04 21/04* 10/04 09/04 Ponded ATU 683 682 662 723* 648 760 * Early rearing of Eagle coho was at the Eagle River hatchery. ATU = Accumulated Temperature Units. f.= females; m. = males 81 Appendix C, T a b l e I I . The dates and d e t a i l s of the sample weights c o l l e c t e d from the s t r a i n s i n the s i x stock comparison. The sampling was used as a t o o l m a i n t a i n s t o c k i n g d e n s i t y of each of the r e a r i n g group 1 s t o c k s a t l e s s than 35 kg/m3. Date D e s c r i p t i o n Comments Jun. 6, 1988 Biomass and sample weights J u l . 27, 1988 Biomass f o r a l l but Eagle J u l . 31, 1988 Biomass weight f o r Eagle a d j u s t d e n s i t y Aug. 13, 1988 Biomass and sample wts. Aug. 27, 1988 Biomass weights a d j u s t d e n s i t y Oct. 1, 1988 Biomass and i n d i v i d u a l weight Oct. 27, 1988 Biomass and i n d i v i d u a l weight a d j u s t d e n s i t y Dec. 8, 1988 Biomass and i n d i v i d u a l weight a d j u s t d e n s i t y Jan. 5, 1989 Biomass and i n d i v i d u a l weight Jan. 21, 1989 Biomass weights & f i s h counts a d j u s t d e n s i t y Mar. 25, 1989 Biomass weights & f i s h counts a d j u s t d e n s i t y Biomass = T o t a l weight o f a l l f i s h i n the tank was measured. I n d i v i d u a l weight = A sample of f i s h were i n d i v i d u a l l y weighed. F i s h counts = A count of a l l f i s h i n the tank was done. A d j u s t d e n s i t y = F i s h were removed from tanks so t h a t a l l d e n s i t i e s were s i m i l a r t o the lowest d e n s i t y measured. 82 Appendix C, T a b l e I I I . Date of the s t a r t of c h a l l e n g e t e s t conducted i n the s i x s t o c k comparison. See the M a t e r i a l s and Methods s e c t i o n of the t e x t f o r d e t a i l s on the c h a l l e n g e s themselves. S t a r t of Experiment Challenge Experiment October 9, 1988 Sal t w a t e r Challenge 1 a t 30ppt NaCl. October 12, 1988 Sal t w a t e r Challenge 1 c o n t r o l s . October 30, 1988 High pH c h a l l e n g e 1 a t pH 9.4 October 30, 1988 High pH c h a l l e n g e 2 a t pH 9.4 November 8, 1988 High pH c h a l l e n g e 1 c o n t r o l s . November 8, 1988 High pH c h a l l e n g e 2 c o n t r o l s . December 8, 1988 Sal t w a t e r c h a l l e n g e 2, 30 ppt NaCl p l u s temperature i n c r e a s e . December 10, 1988 Sa l t w a t e r Challenge 2, temperature i n c r e a s e o n l y . December 16, 1988 Low pH c h a l l e n g e 1 a t pH 3.55. December 18, 1988 Low pH c h a l l e n g e 1 c o n t r o l s a l s o , S a l t w a t e r c h a l l e n g e 2 c o n t r o l s . February 11, 1989 High pH c h a l l e n g e 3 a t pH 9.8. February 14, 1989 High pH c h a l l e n g e 3 c o n t r o l s . March 24, 1989 Thermal t o l e r a n c e c h a l l e n g e a t loC/h A p r i l 29, 1989 Low pH c h a l l e n g e 2 and 4 c o n t r o l s . May 1, 1989 Low pH c h a l l e n g e 3 and 5 c o n t r o l s . May 4, 1989 Low pH c h a l l e n g e 2 a t pH 3.63. May 9, 1989 Low pH c h a l l e n g e 3 a t pH 3.67 May 16, 1989 Low pH c h a l l e n g e 4 a t pH 3.75 May 26, 1989 Low pH c h a l l e n g e 5 a t pH 4.10. June 11--13, 1989 Handling Challenge 1, 30s d i p net. June 16--18, 1989 Handling Challenge 2, 30s d i p net. June 20--22, 1989 Handling Challenge 3, 30s d i p net. 83 Appendix D D e f i n i t i o n s 84 A. Stock A g e n e r a l d e f i n i t i o n i s : a s p e c i e s group, o r p o p u l a t i o n , of f i s h t h a t maintains and s u s t a i n s i t s e l f over time i n a d e f i n a b l e area (Brooke 1981). B. S t r e s s The n o n s p e c i f i c response of the body t o any demand. The s t a t e i s manifested by a s p e c i f i c syndrome (g e n e r a l a d a p t a t i o n syndrome) which c o n s i s t s of a l l of the non-s p e c i f i c a l l y induced changes w i t h i n a b i o l o g i c a l system. The response has a c h a r a c t e r i s t i c form, but no p a r t i c u l a r s p e c i f i c cause (Selye 1976). The p h y s i o l o g i c a l apparatus i n v o l v e d i n emotional o r a r o u s a l r e a c t i o n s t o t h r e a t e n i n g o r upl e a s a n t f a c t o r s i n the l i f e s i t u a t i o n as a whole (Mason 1971). A s t a t e caused by a f a c t o r ( s t r e s s o r ) t h a t r e s u l t s i n d e v i a t i o n from the normal r e s t i n g o r homeostatic s t a t e . While the, the s t r e s s f a c t o r cannot be d i r e c t l y q u a n t i f i e d , the response experienced can ( a f t e r d e c i d i n g what c o n s i t u t e s a normal r e s t i n g s t a t e ) . The s t r e s s response i s the change i n b i o l o g i c a l c o n d i t i o n beyond the normal r e s t i n g range t h a t c h a l l e n g e s homeostasis and may t h r e a t e n the f i s h ' s w e l l b e i n g (Barton and Iwama 1990). "There are few concepts t h a t have evoked as much d i s c u s s i o n and disagreement as t h a t o f s t r e s s when a p p l i e d t o b i o l o g i c a l systems." 1 1 P i c k e r i n g , A.D. I n t r o d u c t i o n t o the concept of s t r e s s , i n P i c k e r i n g A.D. E d i t o r . S t r e s s and F i s h . Academic Press Inc. London 1981. pg 1. 85 

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