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Responses of sockeye salmon (Oncorhynchus nerka) embryos to intragravel incubation environments in selected… Cope, R. Scott 1996

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RESPONSES OF SOCKEYE SALMON (Oncorhynchus nerka.) EMBRYOS INTRAGRAVEL INCUBATION ENVIRONMENTS IN SELECTED STREAMS WITHIN THE STUART - TAKLA WATERSHED by R. SCOTT COPE B.Sc, U n i v e r s i t y OF V i c t o r i a , 1993 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Zoology, F i s h e r i e s Centre) We accept t h i s t h e s i s as conforming to the req u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA APRIL 1996 © - R. Scott Cope 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. The University of British Columbia Vancouver, Canada Department DE-6 (2/88) ABSTRACT Before impacts of f o r e s t h a r v e s t i n g can be i d e n t i f i e d , the n a t u r a l p h y s i c a l and b i o l o g i c a l i n f l u e n c e s on i n c u b a t i o n processes must be understood w i t h i n i n t e r i o r B r i t i s h Columbia watersheds. The e a r l y S tuart stock of sockeye salmon {Oncorhynchus nerka) u t i l i z e the most n o r t h e r l y nursery h a b i t a t of the Fraser R i v e r sockeye s t o c k s . This has l e d to s p e c u l a t i o n that production may be l i m i t e d by h i g h overwinter i n c u b a t i o n m o r t a l i t y . An in situ i n c u b a t i o n study was conducted on four adjacent t r i b u t a r i e s of the Stuart -Takla watershed (Kynock, F o r f a r , G l u s k i e , Bivouac c r e e k s ) , during the 1993 and 1994 broodyears. The study o b j e c t i v e was to estimate overwinter s u r v i v a l of sockeye salmon embryos w i t h i n various redd micro-environments. I t was hypothesized that spawning salmon s e l e c t incubation s i t e s based on environmental cues to optimize egg to f r y s u r v i v a l . Egg to pre-emergent , f r y bioassays, i n conjunction w i t h m i c r o h a b i t a t environmental monitoring, were implemented to d e f i n e a range of n a t u r a l spawning c o n d i t i o n s and t h e i r r e l a t i v e c o n t r i b u t i o n to f r y r e c r u i t m e n t . R e s u l t s demonstrate that high q u a l i t y , r e l a t i v e l y i n v a r i a n t i n c u b a t i o n environment r e s u l t e d i n the l a c k of c l a s s i c a l r e l a t i o n s observed i n previous s t u d i e s between i n c u b a t i o n parameters and s u r v i v a l . . P h y s i c a l processes ( i . e . h y d r a u l i c regime, bedload c h a r a c t e r i s t i c s ) and b i o l o g i c a l processes ( i . e . mass c l e a n i n g by high d e n s i t i e s of spawning adults) r e s u l t i n uniformly high q u a l i t y g r a v e l c o n d i t i o n s w i t h p e r m e a b i l i t i e s , surface water interchange, and i n t r a g r a v e l d i s s o l v e d oxygen l e v e l s a s s o c i a t e d w i t h high incubation success. A l t e r n a t i v e hypotheses of random egg d e p o s i t i o n and u n l i m i t e d high q u a l i t y h a b i t a t were r e j e c t e d due t o ; 1) observed s p a t i a l preferences and, 2) e x p a n s i o n / c o n t r a c t i o n of range under d i f f e r e n t annual population s i z e s . Sockeye salmon s u c c e s s f u l l y spawned over a wide range of h a b i t a t s . High d e n s i t y spawning h a b i t a t was the downstream end of pools at the pool r i f f l e i n t e r f a c e . Habitats u t i l i z e d t o a l e s s e r degree i n c l u d e d ; r i f f l e s , stream margins, i n t e r m i t t e n t side channels and p o r t i o n s of the off-channel h a b i t a t . S u r v i v a l r a t e s between these h a b i t a t types were not s i g n i f i c a n t l y d i f f e r e n t i n c o n t r a s t to p r e d i c t i o n s generated from o p t i m a l i t y models. This was due to the d e f i n i t i o n of "marginal" h a b i t a t . In situ redd s i m u l a t i o n s showed s i m i l a r i n t r a g r a v e l . c o n d i t i o n s , i n both low d e n s i t y ( i . e . assumed marginal) and high d e n s i t y ( i . e . assumed preferred) areas. Spawning adults avoided t r u l y marginal areas with i n t r a g r a v e l d i s s o l v e d oxygen l e v e l s below 3.0 mg/1. A number of adaptations which would optimize i n c u b a t i o n success i n northern environments were i d e n t i f i e d w i t h i n the e a r l y S t u a r t stock of sockeye salmon. E a r l y Stuart sockeye r i s k energy d e p l e t i o n and seasonal maximum temperatures duri n g m i g r a t i o n and spawning. By spawning e a r l y i n the season ( J u l . - Aug.), e a r l y Stuart sockeye enjoy advanced embryological development p r i o r to the onset of low water temperatures. Embryos r a p i d l y accumulate the thermal u n i t s necessary to hatch, thereby becoming mobile i n time to avoid f r e e z i n g and d e s i c c a t i o n as water-levels d e c l i n e and reach seasonal minima. Embryos and a l e v i n s of the e a r l y S t u a r t stock can apparently t o l e r a t e temperature c o n d i t i o n s p r e v i o u s l y considered l e t h a l . Fry s u c c e s s f u l l y emerge i n the s p r i n g a f t e r accumulating l e s s thermal u n i t s than any other Fraser r i v e r stock. The trade o f f again s t t h i s s t r a t e g y i s the e f f e c t of unu s u a l l y s t r e s s f u l m i g r a t i o n c o n d i t i o n s on the q u a l i t y and v i a b i l i t y of the gametes. Evidence of t h i s trade o f f was obtained i n 1994, when egg s u r v i v a l rates were very low f o r spawners that a r r i v e d l a t e and had suffered severe thermal s t r e s s during m i g r a t i o n . i v TABLE OF CONTENTS ABSTRACT i i TABLE OF CONTENTS V LIST OF TABLES v i i LIST OF FIGURES v i i i ACKNOWLEDGEMENTS x i CHAPTER 1 - INTRODUCTION 1 G e n e r a l I n t r o d u c t i o n 1 N a t u r a l H i s t o r y 2 E n v i r o n m e n t a l F a c t o r s A f f e c t i n g I n c u b a t i o n S u r v i v a l . . . 3 I n c u b a t i o n H a b i t a t S e l e c t i o n 7 O b j e c t i v e s 9 CHAPTER 2 - MATERIALS AND METHODS 12 S t u d y A r e a 12 M a t e r i a l s and Methods 16 Egg C a p s u l e I m p l a n t a t i o n E x p e r i m e n t 16 S i t e S e l e c t i o n 16 I n c u b a t i o n c a p s u l e s 17 F e r t i l i z a t i o n P r o c e d u r e 18 E n v i r o n m e n t a l M o n i t o r i n g 21 A d d i t i o n a l I n c u b a t i o n E x p e r i m e n t s 22 S t r eam F i d e l i t y E x p e r i m e n t 22 I n c u b a t i o n T r a n s e c t s 23 C a p s u l e e f f e c t s 24 I n t r a g r a v e l B e h a v i o u r o f A l e v i n s 24 CHAPTER 3 - RESULTS 2 6 Spawner Abundance and D i s t r i b u t i o n 2 6 Egg t o P re -emergen t F r y S u r v i v a l 3 0 P h y s i c a l E n v i r o n m e n t 32 E f f e c t s o f E n v i r o n m e n t a l F a c t o r s on I n c u b a t i o n S u r v i v a l 42 A l e v i n Development and B e h a v i o u r 48 CHAPTER 4 - DISCUSSION 55 S p a t i a l p r e f e r e n c e s 56 M i c r o - H a b i t a t 56 D i s t r i b u t i o n on t h e spawning g rounds 57 I n c u b a t i o n S u r v i v a l 58 E f f e c t s o f E n v i r o n m e n t a l F a c t o r s on I n c u b a t i o n S u r v i v a l 61 Tempera tu re and Embryo Development - 6 1 G r a v e l Q u a l i t y and D i s s o l v e d Oxygen 64 S t r e s s 66 CHAPTER 5 - CONCLUSION 73 V LITERATURE CITED 76 APPENDIX A 91 APPENDIX B 98 APPENDIX C 100 v i LIST OF TABLES Table 1. Sockeye salmon adult escapement estimates and f r y production estimates (T. Whitehouse, D.F.O., Stock Assessment Group, unpubl. data) and corresponding egg to pre-emergent f r y s u r v i v a l r a t e estimates f o r the e a r l y Stuart study streams of Middle R i v e r and Takla Lake (1993 and 1994 broodyears) 28 Table 2. Summary of stream and i n t r a g r a v e l p h y s i c a l parameters f o r p r e f e r r e d and marginal redd s i m u l a t i o n s ( a l l l o c a t i o n s , creeks and years combined) 3 5 Table 3. Summary of stream and i n t r a g r a v e l p h y s i c a l parameters by general h a b i t a t type (margin, thalweg, p o o l , off-channel) f o r a l l seasons (1993 - 1994), creeks (n=4) and l o c a t i o n s combined (n=563) 39 Table 4. Summary of stream and i n t r a g r a v e l p h y s i c a l parameters and corresponding embryo s u r v i v a l r a t e s f o r in situ redd.stranding s i m u l a t i o n s and p r e f e r r e d (control) redd s i m u l a t i o n s . Embryos were f e r t i l i z e d and i n c u b a t i o n capsules planted i n l a t e August. Experiment was terminated i n mid-February under seasonal minima c o n d i t i o n s f o r discharge and temperature 50 v i i LIST OF FIGURES F i g u r e 1. The Fraser R i v e r watershed d e p i c t i n g the l o c a t i o n of the Stuart - Takla watershed. . 13 Figure 2. Experimental study area showing Bivouac, G l u s k i e , F o r f a r , and Kynock creeks and s e l e c t e d i n t e n s i v e sampling reaches 14 Fig u r e 3. Egg in c u b a t i o n capsules and i n c u b a t i o n bags u t i l i z e d as bioassays (from l e f t to r i g h t ; standard capsules - 12 cm length, Behaviour capsule - 46 cm leng t h , i n c u b a t i o n bag - volume 0.2 m3) . Note redd • s t r a n d i n g s i m u l a t i o n excavated i n background (area - 2m2). 19 Fig u r e 4. Adult sockeye a r r i v a l t i ming at F o r f a r Creek mouth. Number of adult sockeye was the d a i l y t o t a l sockeye through the fence at the mouth of F o r f a r Creek. The p e r i o d J u l y 29 - August 2, 1993 was u n a v a i l a b l e due to a fr e s h e t event removing the counting fence d u r i n g t h i s p e r i o d . D a i l y escapement was c o n s e r v a t i v e l y estimated at 3 000 based on peak l i v e counts p l u s cummulative dead (G. Smith, D.F.O., Stock Assessment Group, unpubl. data) 27 Figur e 5. Redd l o c a t i o n s determined through e t h o l o g i c a l o b s e r v a t i o n (July 31, Aug. 1 and Aug 5 1993) w i t h i n G l u s k i e 400 m study reach. Transects 1 and 5, and in c u b a t i o n capsule l o c a t i o n s (redd s i m u l a t i o n s ) were i n c l u d e d f o r reference p o i n t s (see Appendix A). Stream wetted surface area was surveyed Sept. 18, 1993. Note stranded redd l o c a t i o n s along stream margins 2 9 F i g u r e 6. Percent m o r t a l i t y of embryos assessed at the end of each r e t r i e v a l p e r i o d f o r a l l study streams combined (mean +/- 2*S.E.). Note f e r t i l i z a t i o n = 0-2 days (Aug.), Pre-hatch = 2-50 days ( l a t e Sept.), a l e v i n = 50-180 days ( l a t e Dec. - Feb.), pre-emergent f r y = 180-260 days (mid A p r i l ) 31 Fig u r e 7. Comparison of s u r v i v a l r a t e ( f e r t i l i z a t i o n to pre-hatch embryos; 50 days) between redd s i m u l a t i o n bags (n=10) u t i l i z i n g r e p r e s e n t a t i v e in situ s u b s t r a t e composition and standard egg in c u b a t i o n capsules (mean +/- 95% confidence i n t e r v a l ) . Incubation l o c a t i o n s were arrayed across study creeks (FLH = F o r f a r 150m p r e f e r r e d redd s i m u l a t i o n . FLL =Forfar 150m marginal. KLS1 = Kynock 350m stra n d i n g s i m u l a t i o n . KHH = Kynock 1550m p r e f e r r e d . KHL = Kynock 1550m marginal.) 33 v i i i F i g u r e 8. F o r f a r Creek lower watershed (150 m) redd s i m u l a t i o n s . Photographs depict c o n d i t i o n s t y p i c a l of a) marginal and b) p r e f e r r e d i n c u b a t i o n h a b i t a t s (photographs were taken 14 days post f e r t i l i z a t i o n ) . . . 34 Figur e 9. D a i l y maximum temperatures i n F o r f a r Creek f o r the p e r i o d 1990 - 1994 (B. Anderson, D.F.O., P.B.S., unpubl. data) 37 Figur e 10. E a r l y Stuart spawning p e r i o d (20 J u l y - 20 August) d a i l y maximum stream temperatures i n ; a) Kynock, b) F o r f a r , and c) Gl u s k i e creeks f o r the broodyears 1993 and 1994 (B. Anderson, D.F.O., P.B.S., unpubl. data) . . 38 Figure 11. Hydro-meteorological data recorded i n G l u s k i e Creek watershed i n c l u d i n g mean d a i l y flows f o r the water-year November 1, 1991 to October 31, 1992 and t o t a l d a i l y r a i n f a l l f o r A p r i l 27 to October 20, 1992 . 40 Fig u r e 12. Frequency d i s t r i b u t i o n of stream (n=771) and i n t r a g r a v e l (n=784) d i s s o l v e d oxygen measurements w i t h i n the four study streams from the p e r i o d 1992 - 1995 . . . 43 Figure 13. W i t h i n study reach v a r i a t i o n f o r d i s s o l v e d oxygen and temperature f o r the standpipe sampling g r i d of Kynock Creek 1550 m (mid-watershed), 4 A p r i l 1994. Temperature and d i s s o l v e d oxygen were measured at an i n t r a g r a v e l depth of 2 0 cm. Standpipes were grouped by h a b i t a t c l a s s i f i c a t i o n code (l=thalweg, r i f f l e , 2=margin, 3=pool, g l i d e , 4=off-channel) 44 Fig u r e 14. Li n e a r r e g r e s s i o n of the 1994 embryo s u r v i v a l r a t e ( a l l creeks, l o c a t i o n s ) 50 days a f t e r f e r t i l i z a t i o n on the corresponding i n t r a g r a v e l d i s s o l v e d oxygen (@ 2 0 cm depth) at the p e r i o d immediately p r i o r to egg d e p o s i t i o n 46 Fig u r e 15. The 1994 embryo s u r v i v a l r a t e (%) from the tr a n s e c t experimental reach (Kynock 1550 m s i t e ; Appendix A) 50 days a f t e r f e r t i l i z a t i o n versus the corresponding i n t r a g r a v e l d i s s o l v e d oxygen (@ 20 cm depth) at the p e r i o d immediately p r i o r to egg d e p o s i t i o n . Transect runs from the north bank margin (A) across a r i f f l e and pool i n t o the off-channel h a b i t a t (B) . . . . 47 Figure 16. Mean capsule s u r v i v a l r a t e (50 days post f e r t i l i z a t i o n ) f o r f e r t i l i z a t i o n procedures by date f e r t i l i z e d and creek. A. 1993 f e r t i l i z a t i o n batches and corresponding s u r v i v a l r a t e s . B. 1994 f e r t i l i z a t i o n batches and corresponding s u r v i v a l r a t e s 49 i x F i g u r e 17. I n t r a g r a v e l p a t t e r n of changes i n v e r t i c a l d i s t r i b u t i o n of sockeye a l e v i n s i n r e l a t i o n to depth of f r e e z i n g . A. 2 cm depth of f r e e z i n g w i t h i n s u b s t r a t e . B. 15 cm. C. 40 cm 52 Figure 18. Accumulated mean d a i l y temperature units(°CTU) observed f o r the two years of in c u b a t i o n study w i t h i n Kynock, F o r f a r , G l u s k i e and Bivouac creeks. Temperature data was from B. Anderson, D.F.O., P.B.S., unpubl. data. Developmental stages were determined from capsule embryos r e t r i e v e d i n Late September, Mid-December, and m i d - A p r i l u t i l i z i n g the c l a s s i f i c a t i o n system of V e r n i e r (1969) . 53 Figure 19. D a i l y maximum, minimum and mean water temperatures from the Fraser R i v e r at H e l l ' s Gate (average from 1945 - 1993), compared w i t h the 1993 and 1994 mean d a i l y temperatures 69 Figure 20. Mean e a r l y Stuart r e c r u i t s per spawner f o r each one degree C e l s i u s increment of mean J u l y F r a s e r R i v e r water temperature at H e l l ' s gate f o r the p e r i o d 1948 -1989. R e c r u i t s per spawner c a l c u l a t e d from INPFC sockeye database ( I . W i l l i a m s , D.F.O., P.B.S, unpubl. data) based on returns c a l c u l a t e d from estimated catch p l u s escapement on a four year r e t u r n c y c l e . Mean J u l y Fraser R i v e r water temperature c a l c u l a t e d f o r each corresponding year from H e l l ' s Gate database 70 x ACKNOWLEDGEMENTS I wish to express my sincere gratitude and a p p r e c i a t i o n to Dr. Steve Macdonald, my f u n c t i o n a l s u p e r v i s o r , f o r h i s i n i t i a l suggestion of t h i s study. His r e l e n t l e s s guidance, moral, l o g i s t i c and f i n a n c i a l support throughout t h i s study were i n t e g r a l . I am a l s o very g r a t e f u l to C h a r l i e Scrivener, Bruce Anderson, Dr. Peter T s c h a p l i n s k i and Glenn Smith f o r t h e i r a s s i s t a n c e and support i n s e t t i n g up the f i e l d experiments and c o l l e c t i n g the r e s u l t s . I am a l s o t h a n k f u l to the time and e f f o r t c o n t r i b u t e d by a l l the St u a r t - T a k l a working group members. I wish to thank my U n i v e r s i t y s u p e r v i s o r , Dr. C a r l Walters, f o r h i s guidance, support, c r i t i c a l review of the manuscript and endless source of i n s i g h t . I am also g r a t e f u l to my other committee members, Dr. Steve Macdonald, Dr. Tony P i t c h e r , Dr. Peter T s c h a p l i n s k i and Dr. W i l l i a m N e i l l , f o r t h e i r review of the manuscript. Research funds and l o g i s t i c a l support were provided by the Department of F i s h e r i e s and Oceans ( B i o l o g i c a l Sciences Branch) through the Fraser R i v e r Sustainable Development Program. The Na t u r a l Sciences and Engineering Research C o u n c i l of Canada provided me w i t h personal f i n a n c i a l support f o r two years through a post-graduate s c h o l a r s h i p . Both these sources of funding were c r i t i c a l f o r the completion of t h i s t h e s i s and I am g r a t e f u l to them f o r t h e i r support. x i CHAPTER 1 - INTRODUCTION General Introduction Sockeye salmon provide one of the most valuable of Canada's P a c i f i c Coast f i s h e r i e s . Their use by native peoples i s of long standing, and commercial f i s h e r i e s date to the l a t e 1800s (Hart 1973, Ricker 1987) . The current commercial harvest of Fraser River sockeye salmon i s valued at $260 m i l l i o n annually (Henderson and Healey 1993). Sockeye incubation streams also drain watersheds containing valuable timber. The close association of salmon streams with timbered watersheds creates pot e n t i a l problems for fishery management. Timber harvesting can have negative a f f e c t s on salmon incubation environments (Hall and Lantz 1969, Ringler and Hall 1975, P l a t t s et. a l . 1989). There has been a long history of coastal-based f i s h - f o r e s t r y i n t e r a c t i o n research projects (FFIRP) within B r i t i s h Columbia (Poulin 1984, Hartman and Scrivener 1990) and the United States (Sheridan and McNeil 1968, Burns 1970, Moring 1975), and only limited study of i n t e r i o r watersheds (Slaney et. a l . 1977, Sterling 1985) . Given the amount of i n t e r i o r forestry a c t i v i t y and the lack of knowledge concerning over-wintering incubation processes, there i s an urgent requirement for ecological studies to guide land-use practices that are appropriate for the s p e c i f i c physical and b i o l o g i c a l conditions of i n t e r i o r watersheds. To develop such an understanding the Stuart - Takla FFIRP was i n i t i a t e d i n 1990 (Macdonald et. a l . 1992). 1 Before any impacts from f o r e s t h a r v e s t i n g can be estimated, n a t u r a l p h y s i c a l and b i o l o g i c a l i n f l u e n c e s on i n c u b a t i o n processes must be understood w i t h i n these i n t e r i o r watersheds. This t h e s i s examines the n a t u r a l i ncubation environment before l o g g i n g , w i t h s p e c i f i c focus on spawner h a b i t a t s e l e c t i o n , the p h y s i c a l i n c u b a t i o n environment, and embryo s u r v i v a l . This i n t r o d u c t o r y chapter reviews the r e l e v a n t l i t e r a t u r e concerning the e a r l y Stuart sockeye salmon stock, spawner h a b i t a t s e l e c t i o n , the p h y s i c a l i ncubation environment and how these f a c t o r s i n f l u e n c e embryo s u r v i v a l . Chapter two d e s c r i b e s the study area and methods. Chapter three presents the r e s u l t s of experiments f o r the 1993 and 1994 broodyears. Chapter four d i s c u s s e s the over-winter i n c u b a t i o n success of e a r l y Stuart sockeye salmon and a s s o c i a t e d p h y s i c a l and b i o l o g i c a l processes. F i n a l l y , a summary of conclusions and management i m p l i c a t i o n s are presented i n chapter f i v e . Natural History Incubation s u r v i v a l i s i n f l u e n c e d by two main f a c t o r s ; 1) how adults choose incubation s i t e s and, 2) the environment w i t h i n those s i t e s . The remainder of t h i s chapter reviews these f a c t o r s . P a c i f i c salmon are anadromous and semelparous. The e a r l y S t u a r t sockeye salmon mi g r a t i o n represents an extreme case. This stock migrates to the northernmost Fraser R i v e r watershed («1 100 km; a l t i t u d e 691 m; I d l e r and Clemens 1959), and i s the f i r s t to commence spawning w i t h i n t h i s system, (July 20 - August 20; K i l l i c k 2 1955) . Females e s t a b l i s h o v i p o s i t i o n t e r r i t o r i e s and c o n s t r u c t several nests, c o l l e c t i v e l y c a l l e d a redd (Fleming and Gross 1994). The eggs are covered w i t h g r a v e l and the female guards the nest u n t i l her death (Van Den Berge and Gross 1986). The p e r i o d of egg incubation extends through winter with f r y emergence oc c u r r i n g from A p r i l to June (Hickey and Smith 1991). H i s t o r i c a l l y the e a r l y Stuart sockeye stock has never been large, and has been unusually v a r i a b l e (Cooper and Henry 1962, Cass 1989). The c o n s t r u c t i o n of fishways at H e l l ' s Gate, coupled w i t h r e g u l a t o r y p r o t e c t i o n i n the commercial f i s h e r y had i n c r e a s e d the average s i z e of the run about seven times by 1961 to 328 000 (average a l l c y c l e y e a r s ) . Pre-1948 abundances averaged l e s s than 50 000 (Cooper and Henry 1962). Since 1952, r e t u r n s have been h i g h l y v a r i a b l e w i t h no trend i n abundance (Cass 1989). Spawning escapements on the dominant c y c l e averaged 208 000/yr and ranged from 23 000 i n 1965 to 582 000 i n 1949 (Cass 1989) . The other three c y c l e years had average escapements between 17 000 and 51 000 (Hickey and Smith 1991). The t o t a l e a r l y Stuart production capacity i n terms of p o s t u l a t e d spawning area has been estimated at 632 000 spawners (Anon 1988) . With average sockeye escapements of 2 08 000 there appears to be much u n d e r - u t i l i z e d production capacity (Langer et . a l . 1992) . ; Environmental Factors A f f e c t i n g Incubation Survival The e a r l y Stuart stock of sockeye salmon u t i l i z e the most n o r t h e r l y spawning habitat of the Fraser River salmon stocks. There 3 i s a l s o an apparent u n d e r - u t i l i z e d production c a p a c i t y . This had l e d to s p e c u l a t i o n that production of the e a r l y S t u a r t stock of sockeye salmon may be l i m i t e d by environmental f a c t o r s . These p o t e n t i a l l i m i t a t i o n s to sockeye production has r a i s e d i n t e r e s t i n developing an enhancement f a c i l i t y to increase f r y production (SEP-Engineering 1988, Langer e t . a l . 1992). This t h e s i s examines those factors which may impact incubation s u r v i v a l and f r y production. Nest " q u a l i t y " presumably a f f e c t s embryo s u r v i v a l . The s u r v i v a l rate to pre-emergent f r y r e f l e c t s the s e v e r i t y of the environmental c o n d i t i o n s and the a d a p t a b i l i t y of the f r y (Koski 1975). The environmental f a c t o r s g e n e r a l l y considered to a f f e c t egg to emergence s u r v i v a l are water discharge (Hunter 1959, McNeil 1968, 1969), p e r m e a b i l i t y and g r a v e l q u a l i t y (see Chapman 1988 f o r review), d i s s o l v e d oxygen ( A l d e r d i c e e t . a l . 1958, Koski 1966, 1975, Bjornn and Reiser 1991), temperature i n the i n c u b a t i o n environment (Brannon 1987, Velson 1987, Beacham and Murray 1990), s t a b i l i t y of the g r a v e l bed (Hunter 1959, McNeil 1966, L i s l e and Lewis 1992), and upwelling groundwater (Kogl 1965, Hansen 19.75, Leeman 1993).. Temperature i s one of the primary p h y s i c a l f a c t o r s i n f l u e n c i n g the l i f e h i s t o r y t r a i t s of P a c i f i c salmon (Brannon 1987, Burgner 1991). Numerical data {Oncorhynchus spp.) have been compiled f o r the i n f l u e n c e of temperature on i n c u b a t i o n success (Velson 1987) . The m a j o r i t y of t h i s database has been d e r i v e d from B r i t i s h Columbia salmonid hatc h e r i e s and l a b o r a t o r y experiments u t i l i z i n g c o a s t a l broodstock. As a r e s u l t , data on m o r t a l i t y i s scarce f o r stocks and temperatures l e s s than 5 °C (Velson 1987). In general, sockeye embryos and al e v i n s are not w e l l adapted to survive at high i n c u b a t i o n temperatures (Murray and McPhail 1988, Beacham and Murray 1990). The estimated upper temperature of 50% m o r t a l i t y f o r sockeye salmon embryos was 15.5 °C (Beacham and Murray 1990) . Based on t h i s composite database the recommended i n c u b a t i o n temperature range of sockeye salmon was 4.4-13.3°C (Bjornn and R e i s e r 1991). P o p u l a t i o n - s p e c i f i c differences i n developmental bio l o g y have been demonstrated and may r e f l e c t adaptation to the thermal c o n d i t i o n s experienced during development (Beacham and Murray 1987, 1988, 1989, Murray and McPhail 1988). I n t e r i o r stocks have f a s t e r development rates at co l d e r temperatures than do c o a s t a l s t o cks, and hatch e a r l i e r (Brannon 1987, Beacham and Murray 1989). High m o r t a l i t i e s are common when temperatures are below 1-3°C. However, i n t e r i o r spawning sockeye stocks have higher embryo s u r v i v a l r a t e s at low incubation temperatures (89% @ 2°C) than do c o a s t a l spawning stocks (32% @ 2°C), (Beacham and Murray 1989). The e a r l y Stuart stock of sockeye salmon spawn durin g annual maximum stream temperatures that approach, and may even exceed, upper c r i t i c a l l e v e l s f o r s u c c e s s f u l spawning (Scrivener and Anderson 1994) . Stream temperatures then d e c l i n e to mid-winter lows which may remain at 0°C f o r s e v e r a l months, p o s s i b l y l i m i t i n g overwinter i n c u b a t i o n success (Scrivener and Anderson 1994). Many experiments and f i e l d s t u d i e s have r e l a t e d the s u r v i v a l of salmonid embryos to substrate composition and the r e l a t i v e amount of g r a v e l f i n e s (McNeil and A h n e l l 1964, Koski 1966, H a l l 5 and Lantz 1969, R i n g l e r 1970, R i n g l e r and H a l l 1975, D i l l and Northcote 1970, Slaney et. a l . 1977, L o t s p e i c h and Everest 1981, Tappel and Bjornn 1983, Tagart 1984, Everest e t . a l . 1987, Chapman 1988, S c r i v e n e r and Brownlee 1989, L i s l e and Lewis 1992, Young et . a l . 1991). Substrate composition a f f e c t s two c r i t i c a l p r o p e r t i e s of spawning g r a v e l ; p e r m e a b i l i t y and pore s i z e (Tappel and Bjornn 1983, Brownlee et . a l . 1988, Chapman 1988, P l a t t s e t . a l . 1989). P e r m e a b i l i t y ( a b i l i t y of p a r t i c l e s to transmit water per u n i t of time) i s a commonly used measure of the s u i t a b i l i t y of a redd f o r s u c c e s s f u l i n c u b a t i o n of embryos (Wickett 1954, 1958, 1970, P o l l a r d 1955, Terhune 1958, Coble 1961, Koski 1966, Vaux 1968, Chapman 1988) . The more permeable the g r a v e l redd the g r e a t e r the i n t r a g r a v e l v e l o c i t y and the greater the supply of oxygen (Wickett 1970, Chapman 1988, Scrivener and Brownlee 1989) . Entombment of embryos and a l e v i n s can occur when f i n e m a t e r i a l lodges i n g r a v e l i n t e r s t i c e s (Koski 1975, P h i l l i p s e t . a l . 1975, L i s l e and Lewis 1992) . The primary source of oxygen f o r the i n t r a g r a v e l environment i s the passage of water i n t o and out of the gravel streambed and i s a f f e c t e d by such f a c t o r s as g r a v e l p e r m e a b i l i t y , g r a v e l depth, streambed c o n f i g u r a t i o n and stream discharge (Vaux 1962, Sheridan 1962, Kogl 1965, Wickett 1954, Sowden and Power 1985). Numerous s t u d i e s have l e d to the consensus that low d i s s o l v e d oxygen and reduced water exchange increase embryo m o r t a l i t y (see Chapman 1988, Bjornn and R e i s e r 1991 f o r reviews). Reduced s u r v i v a l could r e s u l t from i n t e r f e r e n c e w i t h the interchange of d i s s o l v e d oxygen due to 6 sediment a c c r e t i o n ( P l a t t s et. a l . 1989). Riparian-zone s u b s t r a t e s i n many i n t e r i o r streams, i n c l u d i n g these study streams, are c h a r a c t e r i z e d by l a r g e amounts of l a c u s t r i n e d e p o s i t s (Slaney e t . a l . 1977, Sanborn 1994). Therefore, p o s t - l o g g i n g i n c r e a s e s i n the d e l i v e r y of f i n e sediments i s a p r i n c i p l e concern of researchers. Reported c r i t i c a l ranges of d i s s o l v e d oxygen d e r i v e d from a r t i f i c i a l streams and l a b o r a t o r i e s were; 0.72 - 3.70 mg/1 (Wickett 1954), 0.72 - 7.19 mg/1 (Alderdice e t . a l . 1958), < 5.0 mg/1 (Bjornn and R e i s e r 1991) . I t i s evident from research on more n a t u r a l systems that d i s s o l v e d oxygen below some minimum l e v e l becomes a major determinant of s u r v i v a l ; 6.0 mg/1 (Koski 1966), 3.0 mg/1 (McNeil 1969, Koski 1975), 5.0 mg/1 (Sowden and Power 1985). Annual v a r i a t i o n s i n the amount and t i m i n g of discharge may cause considerable v a r i a t i o n i n the a v a i l a b i l i t y and s u i t a b i l i t y of spawning grounds (Hunter 1959, McNeil 1968, 1969). Dewatering and f r e e z i n g of embryos i s g e n e r a l l y considered an important cause of m o r t a l i t y i n those i n t e r i o r streams w i t h midwinter flow minima (Reiser and Wesche 1979, N e i l s o n and Banford 1983, Bustard 1986, Chapman et. a l . 1986, Gibson and Myers 1988, Barlaup et. a l . 1994). Sockeye salmon can detect upwelling water patterns (Tautz and Groot 1975, Burgner 1991), and may l i m i t t h e i r spawning d i s t r i b u t i o n to areas of warm water upwelling or groundwater seepage to minimize d e l e t e r i o u s e f f e c t s from c o l d stream water (Kogl 1965) . incubation Habitat Selection Although environmental q u a l i t y u l t i m a t e l y determines i f a 7 f e r t i l i z e d egg w i l l s u r v i v e to produce a f r y , the o p p o r t u n i t y to s u r v i v e i s i n f l u e n c e d by the behaviour of the parents. I t has been found c o n s i s t e n t l y that r e l a t i v e l y high p r o p o r t i o n s of salmon runs spawn i n c e r t a i n areas of streams wh i l e other areas have a low percentage of the run (Hunter 1959) . The p r e c i s e homing a b i l i t y of i n d i v i d u a l s to n a t a l spawning grounds, and the narrow time window over which spawning may be s u c c e s s f u l , u s u a l l y r e s u l t s i n l a r g e numbers of i n d i v i d u a l s competing f o r l i m i t e d nest s i t e s (Foote 1990) . A w i d e l y accepted theory i n f i s h e r i e s management i s the "marginal h a b i t a t theory", derived from o p t i m a l i t y models of h a b i t a t s e l e c t i o n ( i . e . Ideal Free D i s t r i b u t i o n , F r e t w e l l and Lucas 1970; Density-Dependent Habitat S e l e c t i o n , MacCall 1990; Gradation In Habitat Q u a l i t y , Hilborn and Walters 1992). This theory p r e d i c t s that sockeye salmon s e l e c t spawning m i c r o h a b i t a t w i t h the most s u i t a b l e c h a r a c t e r i s t i c s , and only move i n t o "less d e s i r a b l e " areas under crowded conditions (Hunter 1959). I f areas not used when runs are small have r e l a t i v e l y poor c o n d i t i o n s f o r eggs and a l e v i n s , then marginal h a b i t a t exposes animals to i n c r e a s e d r i s k of m o r t a l i t y ( M e r r e l l 1962, McNeil 1968). Marginal areas are those regions which might not c o n s i s t e n t l y provide spawning area e i t h e r by being exposed ( i . e . d e s i c c a t i o n and/or f r e e z i n g ) or by being e x c e p t i o n a l l y poor in c u b a t i o n environment ( i . e . low d i s s o l v e d oxygen, excessive f i n e s ) ( H u n t e r 1959). A number of st u d i e s support the p r e d i c t i o n s d e r i v e d from marginal h a b i t a t theory. F i r s t , embryo s u r v i v a l can vary widely 8 among nests and i s o f t e n c o r r e l a t e d to environmental parameters (Koski 1975, Scrivener 1988, Van Den Berge and gross 1989). Secondly, evidence suggests that competition i n c r e a s e s w i t h nest s i t e q u a l i t y (Foote 1990) and as d e n s i t i e s increase, t e r r i t o r y area decreases (Tautz 1977, Schroder 1982, Fleming and Gross 1994). While mature females can maximize embryo s u r v i v a l by d e p o s i t i n g t h e i r eggs i n a high q u a l i t y nest s i t e (Fleming and Gross 1989), the number of spawning s i t e s i s often l i m i t e d promoting t e r r i t o r i a l behaviour (Foote 1990). This r e s u l t s i n an i n c r e a s i n g p r o p o r t i o n of spawners o c c u r r i n g i n l e s s d e s i r a b l e areas as d e n s i t i e s i n c r e a s e (Ricker 1954, Hunter 1959, L a r k i n 1977, Schroder 1982, N e i l s o n and Banford 1983, Chapman et. a l . 1986). Average breeding success de c l i n e s w i t h density, whereas variance i n female success increases (Fleming and Gross 1994) . This r e s u l t s i n an asymptotic number of r e c r u i t s as spawner numbers increase (Hilborn and Walters 1992). Expansion and c o n t r a c t i o n of population range or d i f f e r e n t i a l u t i l i z a t i o n of marginal h a b i t a t w i t h changes i n p o p u l a t i o n abundance i s a commonly observed phenomenon a s s o c i a t e d w i t h such o p t i m a l i t y models (Hunter 1959, McCall 1990) . Objectives The general o b j e c t i v e s of t h i s study were t o ; 1) d e f i n e n a t u r a l i n c u b a t i o n c o n d i t i o n s i n a set of i n t e r i o r experimental streams which had experienced minimal anthropogenic impacts and, 2) determine responses of embryos to q u a l i t a t i v e and q u a n t i t a t i v e d i f f e r e n c e s i n the various redd micro-environments i n which sockeye 9 spawn. This t h e s i s t e s t s the s p e c i f i c hypothesis that spawning salmon s e l e c t i n c u b a t i o n s i t e s based on environmental cues to optimize egg to f r y s u r v i v a l i n northern environments. Egg to pre-emergent f r y bioassays were placed i n " p r e f e r r e d " and "marginal" h a b i t a t s . Habitat c l a s s i f i c a t i o n was determined by observations of q u a l i t a t i v e h a b i t a t parameters and the s p a t i a l d i s t r i b u t i o n of spawners ( r e l a t i v e d e n s i t i e s ) , w i t h i n each experimental reach. Environmental monitoring was implemented to determine the range of n a t u r a l spawning c o n d i t i o n s and the responses of embryos to hypothesized d i f f e r e n c e s i n the v a r i o u s redd micro-environments. Such an approach makes two assumptions. F i r s t , i n d i v i d u a l f i s h must be able to perceive and respond to d e t e c t a b l e gradients of " s u i t a b i l i t y " . Second, spawning salmon measure s u i t a b i l i t y by u s i n g environmental cues such as d i s s o l v e d oxygen, waterflow, temperature and substrate. These assumptions l e a d to the general p r e d i c t i o n that p r e f e r r e d h a b i t a t w i l l have a higher q u a l i t y and higher egg to pre-emergent f r y s u r v i v a l r a t e , than marginal h a b i t a t . Several s p e c i f i c p r e d i c t i o n s are made: 1) Spawner d i s t r i b u t i o n and egg to emergence s u r v i v a l c o r r e l a t e d to the q u a l i t y of p h y s i c a l parameters being s e l e c t e d f o r . 2.) Contagious spawner d i s t r i b u t i o n , as a r e s u l t of p h y s i c a l parameters. 3.) Coarse s c a l e l o n g i t u d i n a l gradient of p h y s i c a l parameters and i n c u b a t i o n s u r v i v a l w i t h i n a creek. 4.) M i c r o - s c a l e gradient of p h y s i c a l parameters and in c u b a t i o n s u r v i v a l across the margins of a creek. 5.) Density-dependence r e f l e c t e d as spawners being forced 10 i n t o marginal s i t e s w i t h poorer q u a l i t y environmental parameters and lower i n c u b a t i o n success. These p r e d i c t i o n s are f a l s i f i a b l e under s e v e r a l a l t e r n a t i v e s c e n a r i o s . F i r s t , i t could be that egg d e p o s i t i o n i s random (spawners not s e l e c t i n g i n c u b a t i o n s i t e s based on environmental cues to optimize egg to f r y emergence s u r v i v a l ) . Secondly, redd l o c a t i o n s may not be l i m i t e d . The study streams may have u n l i m i t e d h i g h q u a l i t y i n c u b a t i o n h a b i t a t r e l a t i v e to p o t e n t i a l abundance of spawners. F i n a l l y , r a t h e r than s e l e c t i n g s i t e s to optimize i n c u b a t i o n success as hypothesized, spawners may be s e l e c t i n g s i t e s to optimize the spawning act. This a l t e r n a t i v e hypothesis presumes the h a b i t a t requirements f o r spawning may c o n f l i c t w i t h the h a b i t a t requirements f o r s u c c e s s f u l i n c u b a t i o n . 11 CHAPTER 2 - MATERIALS AND METHODS Study Area The Stuart R i v e r watershed c o n s i s t s of three major r i v e r and lake systems which d r a i n south i n t o the Nechako R i v e r . I t represents the most northern extent of the Fraser R i v e r watershed ( F i g . 1) . Two sockeye salmon runs to the Stuart system are i d e n t i f i e d from run tim i n g and spawning d i s t r i b u t i o n . The e a r l y S t uart stock u t i l i z e s more than 30 t r i b u t a r i e s , p r i m a r i l y to Takla Lake and Middle R i v e r (Lat. 55° 00' N, Long. 125° 50' W.). Four adjacent t r i b u t a r i e s (Bivouac, G l u s k i e , F o r f a r , Kynock creeks) were chosen f o r t h i s p r o j e c t ( F i g . 2; Bernard e t . a l . 1994). Comprehensive watershed d e s c r i p t i o n s of the study streams are i n Harder e t . a l . (1989), Hickey and Smith (1991), Langer e t . a l . (1992), and Macdonald et. a l . (1992). B r i e f l y , watersheds are i n the Hogem Range of the Omineca Mountains, the northern end of the sub-boreal spruce b i o g e o c l i m a t i c zone (BCMFL 1988) . Annual p r e c i p i t a t i o n i s *50 cm and occurs almost e x c l u s i v e l y as snow from November to March (Macdonald et. a l . 1992). Veg e t a t i o n cover i s predominantly mature spruce/pine f o r e s t . Study watersheds are small streams which have no flow s t a b i l i z i n g l a c u s t r i n e f e a t u r e s . Twenty-six of the 33 e a r l y Stuart spawning streams f a l l i n t o t h i s category, r e p r e s e n t i n g 44% of the a v a i l a b l e spawning h a b i t a t f o r the stock (Langer e t . a l . 1992). Each stream used i n t h i s study represents «l-7% of the estimated t o t a l spawning c a p a c i t y . Escapements to these three streams represent from 8-42% of the 12 F i g u r e 1. The F r a s e r R i v e r watershed d e p i c t i n g the l o c a t i o n of the S t u a r t - Takla watershed. 13 F i g u r e 2 . Experimental study area showing Bivouac, G l u s k i e , F o r f a r , and Kynock creeks and s e l e c t e d i n t e n s i v e sampling reaches. 14 e n t i r e e a r l y Stuart escapement (Langer e t . a l . 1992). G l u s k i e Creek has a t o t a l watershed area of 55 km2 and i s approximately 19 km long. The lower 0.8 km has a gradient of 1-2%. The upper stream has a gradient of 11% or g r e a t e r . Estimated usable spawning area i s 11 000 m2 w i t h spawning c a p a c i t y estimated at 18 000 a d u l t s assuming a 50:50 sex r a t i o and optimum d e n s i t y of 2 spawners/m 2 (Langer e t . a l . 1992). G l u s k i e represents 3% of the t o t a l estimated production capacity, yet represents between 8-14% of the e n t i r e e a r l y Stuart escapement. Escapements f r e q u e n t l y exceed 10 000 f i s h (Langer et. a l . 1992). F o r f a r Creek has a t o t a l watershed area of 42 km2 and i s approximately 18, km long. The lower 2 km has a g r a d i e n t of 1-2%. The upper creek has a 5% or greater g r a d i e n t . Estimated spawning area i s 10 000 m2, w i t h spawning c a p a c i t y estimated at 18 300 a d u l t s . F o r f a r Creek represents 3% of the t o t a l estimated p r o d u c t i o n c a p a c i t y , yet represents between 9-18% of the e n t i r e e a r l y Stuart escapement. Escapements f r e q u e n t l y exceed 10 000 f i s h (Langer e t . a l . 1992) . Kynock Creek has a t o t a l watershed area of 75 km2 and i s approximately 15 km long. The lower 1.6 km has a gradient of 0.5-2%. The upper creek increases to 7-8% by 3 km. Estimated spawning area i s 23 000 m2 w i t h spawner c a p a c i t y estimated at 47 600 a d u l t s . Kynock Creek represents 7% of the t o t a l estimated p r o d u c t i o n c a p a c i t y , yet represents between 9-42% of the e n t i r e e a r l y S t uart escapement. Escapements f r e q u e n t l y exceed 15 000 f i s h (Langer e t . a l . 1992). 15 Bivouac Creek has a watershed area of 51 km2 and i s approximately 18 km long. The lower 2 km has a g r a d i e n t of 1.5%, then increases to 4%. Estimated spawning area i s 3 000 m2 and spawner c a p a c i t y 5 700 a d u l t s . Bivouac Creek represents 1% of the t o t a l estimated production c a p a c i t y , and represents between <l-3% of the e n t i r e e a r l y Stuart escapement. Escapements are g e n e r a l l y < 1 000 f i s h (Langer e t . a l . 1992). Materials and Methods The main experimental approach was to; 1) map expected h a b i t a t s u i t a b i l i t y ( i . e . redd d i s t r i b u t i o n ) , 2) p l a n t egg capsules to measure space/time v a r i a t i o n s i n s u r v i v a l r a t e and, 3) monitor environmental parameters to determine t h e i r i n f l u e n c e on the expected s u r v i v a l p a t t e r n s . Egg Capsule Implantation Experiment i . ) Site Selection Two study reaches were selected i n each of Gluskie, F o r f a r and Kynock creeks, f o r an i n i t i a l t o t a l of 6 study reaches. Bivouac Creek was added to t h i s study design i n 1994. Study reaches were s e l e c t e d t o ; 1) contain p o o l - r i f f l e - o f f / c h a n n e l h a b i t a t , and 2) be r e p r e s e n t a t i v e of the lower f l o o d p l a i n reaches and mid-watershed reaches. L i n e a l d i s t r i b u t i o n and abundance data f o r the 1992 broodyear i n d i c a t e d the study reaches were p a r t of the core spawning h a b i t a t that occurred from the creek mouth to the 1 230 m, 2 550 m, 2 580 m p o i n t s w i t h i n G l u s k i e , F o r f a r and Kynock 16 creeks respectively (Tschaplinski 1994). The study reaches were partitioned, i n r e l a t i v e terms, into low and high u t i l i z a t i o n spawning habitat. Salmon observed displaying spawning behaviours at regular i n t e r v a l s (Tautz and Groot 1975), had t h e i r redds marked by wooden stakes. The capsule implantation s i t e s were then selected based on expected spawner habitat u t i l i z a t i o n . . High u t i l i z a t i o n habitat was considered "preferred", while low u t i l i z a t i o n habitat was considered "marginal". Two representative in situ redd simulations (2m2), (one marginal, one preferred) were then constructed within each study reach for an i n i t i a l t o t a l of 12 redd simulations (Appendix A). ii.)Incubation capsules Various methods to estimate incubation s u r v i v a l are described i n the l i t e r a t u r e . These include excavation of natural or a r t i f i c i a l redds (Slaney et. a l . 1977, Gustafson-Marjanen and Moring 1984), redd capping (Koski 1966, Tagart 1984) and trapping of downstream migrants (Fish. Res. Bd. Can. 1956, Anon 1968, Hickey and Smith 1991). Survival estimates derived using these methods may be biased due to several factors; 1) decomposition of unsuccessfully developed eggs before recovery, 2) scavenging, 3) predation, 4) intragravel migration or, 5) over-estimation of egg deposition. Alternatively, eggs may be implanted into the gravel i n porous containers (Vibert 1949, Slaney et. a l . 1977, Scrivener 1988, Groot 1989, Perkins and Krueger 1994) . This "bioassay" technique i s appropriately designed to indicate the q u a l i t y of 17 spawning h a b i t a t . However, chambers o f t e n c l u s t e r eggs i n u n n a t u r a l l y h i g h numbers and the capsules can become traps f o r sediment and encourage the growth of fungus (Harshbarger and Porter 1979, Bams 1985, Greenberg 1992). In t h i s study, egg development capsules were modelled a f t e r Scrivener (1988) and Groot (1989). These capsules mimic egg pocket centrum c o n d i t i o n s (Chapman 1988). They a l s o provided s u f f i c i e n t water exchange and s p a t i a l separation of eggs to remain f r e e of saprophytic fungi and accumulating f i n e s i n c o a s t a l B r i t i s h Columbia streams (Scrivener 1988) . This capsule design requires minimal supervision, would remain unhampered by i c e and the extremes of a northern c l i m a t e , and co u l d be e a s i l y recovered. Incubation capsules were s t a i n l e s s s t e e l c y l i n d e r s (37 mm i n s i d e diameter) w i t h 2.3 mm diameter holes set at 2.0 mm centres. The ends were covered with s n u g - f i t t i n g polyethylene t e s t caps with numerous 2.3 mm holes. A colour coded wire leading from the capsule to the g r a v e l surface marked the capsule s i t e and a s s i s t e d w i t h r e t r i e v a l . Two lengths of capsule were u t i l i z e d ; a standard (length = 12 cm) and a longer v e r s i o n f o r behavioral work (length = 46 cm). Behaviour capsules consisted of two 23 cm sections clamped together v e r t i c a l l y ( F i g . 3). i i i . ) Fertilization Procedure Pooled sockeye salmon gametes (4?, 4tf) were c o l l e c t e d from each creek during spawning. Ova were s e l e c t e d from r i p e females (loose eggs e a s i l y extruded by gentle abdominal pressure a p p l i e d 18 F i g u r e 3 . E g g i n c u b a t i o n c a p s u l e s a n d i n c u b a t i o n b a g s u t i l i z e d a s b i o a s s a y s ( f r o m l e f t t o r i g h t ; s t a n d a r d c a p s u l e s - 1 2 c m l e n g t h , B e h a v i o u r c a p s u l e - 4 6 c m l e n g t h , i n c u b a t i o n b a g -v o l u m e 0 . 2 m 3 ) . N o t e r e d d s t r a n d i n g s i m u l a t i o n e x c a v a t e d i n b a c k g r o u n d ( a r e a - 2m 2 ) . 1 9 a n t e r i o r to p o s t e r i o r ) . F i s h were c a r e f u l l y examined f o r m a t u r i t y and any female that appeared to be p a r t i a l l y spawned or immature was not used. F i s h of e i t h e r sex w i t h severe wounds, p h y s i c a l a b n o r m a l i t i e s , or i n g e n e r a l l y poor c o n d i t i o n were a l s o r e j e c t e d . Gametes were stored separately i n polyethylene c o n t a i n e r s which were maintained at moderate temperatures (6-11 °C) w i t h i n gamete t r a n s p o r t boxes. Gametes were f e r t i l i z e d u s i n g the wet method i n c o r p o r a t i n g an i s o t o n i c sodium bicarbonate r i n s e (Wilcox e t . a l . 1984) . T h i r t y eggs, s p a t i a l l y separated by grave l , were placed i n the top 10 cm of each capsule. Capsules (n1993=32 , n1994=22 ) were p l a n t e d v e r t i c a l l y i n each simulated redd at a depth of 2 0 cm, the p r e v i o u s l y determined average redd depth (Macdonald e t . a l . 1992) . A l l p l a n t i n g procedures were completed w i t h i n one hour of f e r t i l i z a t i o n to prevent m o r t a l i t y due to mechanical shock or a g i t a t i o n (Jensen and Alderdice 1983). Fencing m a t e r i a l was secured around each redd s i m u l a t i o n to ensure the capsules were not d i s t u r b e d by the remaining spawners. T y p i c a l l y , each reach w i t h i n each creek represented a unique f e r t i l i z a t i o n event. F e r t i l i z a t i o n success was determined f o r each f e r t i l i z a t i o n event using randomly s e l e c t e d capsules (n=2) r e t r i e v e d 48 hrs a f t e r f e r t i l i z a t i o n . P e r i o d i c random c o l l e c t i o n s of developing embryos (n 1 9 9 3=10 , n1994=6-7 capsules/redd sim u l a t i o n ) were made: 1) Late September - e a r l y October as water temperatures d e c l i n e d r a p i d l y . 2) Late December during low temperature and flow c o n d i t i o n s . 3) M i d - A p r i l to c o i n c i d e w i t h the onset of f r y 20 emergence. Development rates were examined u t i l i z i n g the c l a s s i f i c a t i o n system of Ve r n i e r (1969). A n a l y s i s of egg to f r y s u r v i v a l i n v o l v e d p o o l i n g i n d i v i d u a l capsule s u r v i v a l rates (percent s u r v i v a l normalized by a r c s i n e t r a n s f o r m a t i o n ; Zar 1984) f o r each redd/date r e t r i e v a l by stream, stream reach and s i t e (preferred vs marginal). T e s t i n g f o r between h a b i t a t d i f f e r e n c e s i n s u r v i v a l was by an a l y s i s of variance (ANOVA; SAS 1988) . S u r v i v a l rates were t e s t e d f o r d i f f e r e n c e s between marginal and pre f e r r e d s i t e s nested w i t h i n stream and stream reach. Post-hoc m u l t i p l e comparisons of ANOVA r e s u l t s were done using Duncan's m u l t i p l e range t e s t (SAS 1988). i v . ) Environmental Monitoring Standpipe monitoring s t a t i o n s e s t a b l i s h e d w i t h i n each study reach i n each creek, were u t i l i z e d to c h a r a c t e r i z e stream and i n t r a g r a v e l p h y s i c a l v a r i a b l e s . Standpipe monitoring s t a t i o n s w i t h i n each study reach were based on a s t r a t i f i e d design that ensured a l l stream h a b i t a t types were sampled (stream margin, thalweg, p o o l , o f f - c h a n n e l ) . Standpipe monitoring s t a t i o n s were a l s o located w i t h i n the "marginal" and "preferred" redd simulations where egg capsules were implanted. A t o t a l of 10 to 2 6 standpipes, depending on reach, were sampled f o r each reach i n each sample p e r i o d (Appendix A). Sampling was undertaken before spawning (J u l y 1-13) and during each embryo c o l l e c t i o n p e r i o d ( l a t e September, l a t e December, A p r i l ) . F o l l o w i n g a method developed by Terhune (1958), a standpipe 21 was d r i v e n i n t o the substrate to . a depth of 20 cm to c o l l e c t i n t r a g r a v e l d i s s o l v e d oxygen, temperature and p e r m e a b i l i t y measurements. An i n t e r i o r s e a l i n g rod was used to prevent contamination by surface water during the i n s t a l l a t i o n of the pipe. Temperature and d i s s o l v e d oxygen were measured i n s i d e and adjacent to the standpipe using an Oxyguard probe w i t h a w a t e r - s t i r r e r . At each standpipe l o c a t i o n stream v e l o c i t y and depth measurements were made as w e l l as v i s u a l estimates of the s i z e of s u r f i c i a l streambed m a t e r i a l . R e l a t i v e g r a v e l p e r m e a b i l i t y was determined by pumping water from the standpipe f o r a known len g t h of time ( «5 sec) over a pre-determined head ( 1 " ) . P h y s i c a l parameters were examined f o r d i f f e r e n c e s on a macro-environmental s c a l e (watershed), meso-scale (reaches w i t h i n watersheds) and, on a micro-habitat s c a l e ( h a b i t a t type w i t h i n reaches). M u l t i p l e l i n e a r r e g r e s s i o n a n a l y s i s was used t o t e s t the r e l a t i v e s i g n i f i c a n c e of environmental v a r i a b l e s measured at in c u b a t i o n l o c a t i o n s i n r e l a t i o n to t h e i r corresponding embryo s u r v i v a l . Post-hoc simple l i n e a r regression was used to examine the s i g n i f i c a n c e of each environmental parameter independently. Additional Incubation Experiments i . ) Stream Fidelity Experiment A f u l l y crossed gamete in c u b a t i o n program was i n s t i t u t e d w i t h i n the general habitat study of 1993. The o b j e c t i v e was to t e s t i f genetic d i f f e r e n t i a t i o n between broodstock from the study creeks may impair a b i l i t y of eggs to survive i n nearby creeks. Within each 22 creek redd s i m u l a t i o n s (upper reach, p r e f e r r e d h a b i t a t ) were u t i l i z e d (Appendix A). In a d d i t i o n to the 32 capsules of a creek broodstock, 10 a d d i t i o n a l capsules were p l a n t e d w i t h eggs from the other two study creeks. These 30 capsules (n=10 from each of the creeks) were l e f t f o r the incubation d u r a t i o n and r e t r i e v e d during the f i n a l sampling p e r i o d ( A p r i l 1994). A comparison of gamete v i a b i l i t y between broodstocks, across three study streams was estimated under i d e n t i c a l r e a r i n g c o n d i t i o n s (1 way ANOVA; SAS 1988) . i i . ) Incubation Transects In 1994, bank to bank tr a n s e c t s of i n c u b a t i o n capsules were i n s t a l l e d w i t h i n the Kynock 1550 m study reach (Appendix A l ) . S i t e s e l e c t i o n (n=ll in situ redd simulations) was based on q u a l i t a t i v e and q u a n t i t a t i v e d i f f e r e n c e s i n h a b i t a t parameters, r e g a r d l e s s of expected spawner u t i l i z a t i o n . The obj e c t i v e was to expand the range of environmental parameters beyond those s e l e c t e d by spawning a d u l t s . Based on the 1993 r e s u l t s i t was hypothesized that a "threshold" l e v e l e x i s t e d beyond which spawning females would not u t i l i z e the h a b i t a t . I t was f u r t h e r hypothesized that lower s u r v i v a l r a t e s would r e s u l t from the lower q u a l i t y h a b i t a t beyond these t h r e s h o l d s . E i t h e r 6 or 8 capsules were i n s t a l l e d at each of the 11 redd s i m u l a t i o n s . Capsule r e t r i e v a l (n=2-3 capsules) f o l l o w e d the standard sampling p r o t o c o l . Environmental parameters were measured as p r e v i o u s l y described, w i t h i n each simulated redd. 23 i i i ) Capsule effects A l t e r n a t i v e p e r f o r a t e d containers were designed t o assess the e f f e c t of the in c u b a t i o n capsules on egg to f r y s u r v i v a l ( F i g . 3). These i n c u b a t i o n "bags" were adapted from Perkins and Krueger (1994) . Mesh bags were much l a r g e r («.2m3) and were cons t r u c t e d from mark-rosette c l o t h . Substrate was not s e l e c t e d f o r optimum q u a l i t i e s but to represent the in situ composition. This a l t e r n a t e redd s i m u l a t i o n t e s t e d the concern that s e l e c t i o n of only good q u a l i t y s u b s t r a t e to put i n t o i n c u b a t i o n capsules c r e a t e d micro-h a b i t a t conditions that unnaturally influenced s u r v i v a l . Two "bags" were p a i r e d w i t h 8 standard capsules i n 5 l o c a t i o n s arrayed across creeks (Appendix A). Capsule e f f e c t s were then examined by p a i r e d t - t e s t (Zar 1984). i v . ) Intragravel Behaviour of Alevins C o n s t r i c t i o n of l a r v a l movement w i t h i n i n c u b a t i o n capsules could decrease incubation success i f subgravel behaviour of a l e v i n s ( i . e . v e r t i c a l / l a t e r a l migration) occurs i n response to changing environmental c o n d i t i o n s . F i v e redd s t r a n d i n g s i m u l a t i o n s c o n t a i n i n g 6 be h a v i o r a l i n c u b a t i o n capsules and s i x standard i n c u b a t i o n capsules were arrayed across creeks i n 1994 (Appendix A). The design of the be h a v i o r a l i n c u b a t i o n capsules would permit the v e r t i c a l movement of larvae ( i . e . 46 cm of v e r t i c a l d i s t a n c e versus 12 cm i n standard incubation c a p s u l e s ) . L o c a t i o n s were chosen based on observations during the 1993 s t u d i e s that would l i k e l y be impacted by dewatering or f r e e z i n g . Stranding 24 simulations were generally located w i t h i n stream margins or shallow g r a v e l bars c o n t a i n i n g low den s i t y spawning a c t i v i t y and post-spawning exposed s u r f i c i a l s u bstrate. C o l l e c t i o n s of developing embryos were made; 1) p r i o r to hatc h i n g i n l a t e September as w a t e r l e v e l s and temperatures began to d e c l i n e r a p i d l y and, 2) during the a l e v i n stage i n February duri n g minimum flow and temperature c o n d i t i o n s . W i t h i n each simulated redd, during both r e t r i e v a l p e r i o d s , environmental parameters were measured as p r e v i o u s l y described. The e f f e c t s of dewatering and f r e e z i n g on l a r v a l behaviour and s u r v i v a l rates was i n f e r r e d from; 1) determination of the pre-hatch v e r t i c a l d i s t r i b u t i o n and s u r v i v a l of embryos, 2) c o n t r a s t i n g the v e r t i c a l d i s t r i b u t i o n s of embryos and a l e v i n s w i t h i n behaviour capsules i n r e l a t i o n to key environmental parameters ( i . e . w a t e r l e v e l , temperature) and, 3) examination of s u r v i v a l r a t e s i n r e l a t i o n to environmental c o n d i t i o n s . 25 CHAPTER 3 - RESULTS Spawner Abundance and D i s t r i b u t i o n The e a r l y Stuart escapement t y p i c a l l y occurs between J u l y 22 to August 15, and peak spawning a c t i v i t y occurs between August 3-13 (Fig 4; G. Smith, D.F.O., Stock Assessment Group, unpubl. data). Escapement estimates f o r the study creeks were very d i f f e r e n t between the two years of study (Table 1; T. Whitehouse, D.F.O., Stock Assessment Group, unpubl. data). Based on estimates f o r usable spawning area optimum escapement l e v e l s were exceeded i n 1993 (density = 3.46 spawners/m2) , w h i l e 1994 was w e l l below t h i s l e v e l (density = 0.30 spawners/m2) . During the high d e n s i t y broodyear, abundances were d r a m a t i c a l l y higher at a l l l o c a t i o n s , and d i s t r i b u t i o n s were extended a f u r t h e r 1.2 - 2.0 km upstream to where o b s t r u c t i o n s blocked f u r t h e r movement (P. T s c h a p l i n s k i , M.O.F., Research Branch., per. comm.). Redd d i s t r i b u t i o n s w i t h i n a l l study reaches demonstrated s p a t i a l preferences (n=6). High d e n s i t y spawning h a b i t a t ("preferred") was c o n s i s t e n t l y at the t a i l of pools i n the p o o l -r i f f l e t r a n s i t i o n . Low de n s i t y spawning h a b i t a t s ("marginal") i n c l u d e d ; r i f f l e s , stream margins, i n t e r m i t t e n t side-channels and p o r t i o n s of off-channel h a b i t a t . These s p a t i a l preferences were c o n s i s t e n t over both study years ( F i g . 5, Appendix A). 26 1200 t 1—1 r H r H cn 01 Cn cn Cn cn Cn cn 1 | 1 1 1 i < < I < < i < i << 1 I < i CN >£> 0 0 O r H ro in r H ro in CN CN CN CN ro r H r H r H r H Figure 4. Adult sockeye a r r i v a l timing at Forfar Creek mouth. Number of adult sockeye was the d a i l y t o t a l sockeye through the fence at the mouth of Forfar Creek. The period July 29 -August 2, 1993 was unavailable due to a freshet event removing the counting fence during t h i s period. Daily escapement was conservatively estimated at 3 000 based on peak l i v e counts plus cummulative dead (G. Smith, D.F.O., Stock Assessment Group, unpubl. data). 27 co o CD CD 4-) i—I 4-) T5 co g cn-H - H O) S CO CD O - H 4 J d O -rH T3 CO a g o cd a CD co ^ u -u 3 o rH a . rH CO rH ° ^ c w CO 4-> 4 H „<• h i cO tO (0 4-> *g 0 0 <c • >, r H r H r Q rH 3 CO CD a CD 3 (D - 4-) a o u o co cd g -rH 4_) CO CD u O 4-) c 4 J CD g CD CO u CO CD co O (D O 4 J rH CD cd g g DJ CO - H ^ ro co 4-> cn cj (D co tn CO CO CD r H CD CO < CD T3 4-) G CO cd rH no i—I CTl •38 r g 4-) 0 0 Cd CTl o CD 0) co o o u o oo r G 3 : ,G CD 4-> CD r H r Q CO Eh > rH CD co cO C? fO MH r H r * 4 J CO G CD SH G CD fO g CD U I CD CD > U - H act; Total 6 950 13 900 0.3 6 857 29.5 28.0 ear Kynock 2 148 4 296 0.2 3 408 48.0 60.1 4 Broody Forfar| 2 511 5 022 0.5 2 700 28.9 15.6 199' Gluskie 1 950 3 900 0.4 749 11.6 27.7 Bivouac r—i cxi oo ro t^- oo co C D o r-^  Total 81 265 162 530 3.5 42 116 22.7 49.0 ear Kynock 20 665 41 702 1.8 22 737 35.4 45.8 3 Broody Forfarl 20 665 41 330 4.1 12 083 19.1 49.5 1991 Gluskie 16 749 33 498 3.0 7 296 13.5 50.9 Bivouac 23 000 46 000 15.3 + OO CD CD ^ U " CD CD M— S- 4— + + + + + H-> G CD E >> CD CL ra CJ 00 + + o o o 6-9 E CD CTl s_ CD EE a> CD • r - ^ u_ o. oo i i E >, CT) CT) CD S - CT) CT) • U. UJ UJ 6-9 03 > > CD CO 13 O CD CD +-> ro 4-> ro s_ CT) O s_ Q_ E O +-> rO 5_ CD CL =3 O s_ CD CD E oo 00 CD 00 00 < C 00 CD +-> ro OO CD ro CD s_ <TJ CT) 3 ro Q _ oo CD - Q fO OO CD O H-> CO • OO r— CD -a £ 13 13 C L 00 E 00 =5 < C + OO CD £_ >> ro OO oo ro O j Q CD 25 00 C L ro O E O +-> ro J— X CD co O ro L O CJ H-> • • O ro O "O LO 00 ro I— CD >> CD JXL CJ O OO S_ — , +-> CD OO ro > <T> - Q •r- cn 3 O : r-H u s- . c CD i — r — 00 ro ro CD E O T3 CD E ro CD E E O CD CT) "O E CD 00 ro 00 ro CO ro CD + + + + + 1<3 N F i g u r e 5 . R e d d l o c a t i o n s d e t e r m i n e d t h r o u g h e t h o l o g i c a l o b s e r v a t i o n ( J u l y 3 1 , A u g . 1 a n d A u g 5 1 9 9 3 ) w i t h i n G l u s k i e 4 0 0 m s t u d y r e a c h . T r a n s e c t s 1 a n d 5 , a n d i n c u b a t i o n c a p s u l e l o c a t i o n s ( r e d d s i m u l a t i o n s ) w e r e i n c l u d e d f o r r e f e r e n c e p o i n t s ( s e e A p p e n d i x A ) . S t r e a m w e t t e d s u r f a c e a r e a w a s s u r v e y e d S e p t . 1 8 , 1 9 9 3 . N o t e s t r a n d e d r e d d l o c a t i o n s a l o n g s t r e a m m a r g i n s . 2 9 Egg to Pre-emergent Fry Survival Examination of the sources of v a r i a t i o n f o r embryo s u r v i v a l r a t e s i n d i c a t e d an i n t e r a c t i o n between broodyear and creek (p < 0.01; Appendix B) . This means that the data cannot be analyzed across years f o r each creek i n t e s t i n g f o r h a b i t a t e f f e c t s . S u r v i v a l rates were blocked by broodyear, and s u r v i v a l d i f f e r e n c e s between h a b i t a t s were t e s t e d . The 1993 mean s u r v i v a l r a t e from f e r t i l i z a t i o n to pre-emergent f r y was 49%. Mean s u r v i v a l was 51%, 50% and 46% f o r G l u s k i e , F o r f a r and Kynock creeks r e s p e c t i v e l y . There was no d i f f e r e n c e between s u r v i v a l rates (p > 0.05), and no s i g n i f i c a n t e f f e c t of creek (p > 0.05), reach (p > 0.05) or h a b i t a t type (p > 0.05) . The mean 1994 s u r v i v a l r a t e to pre-emergent f r y was 27%. There was s i g n i f i c a n t v a r i a t i o n i n s u r v i v a l r a t e s between creeks (p < 0.01), but not reaches w i t h i n each creek (p > 0.05), or h a b i t a t type w i t h i n reaches (p > 0.05). Mean s u r v i v a l r a t e was lowest i n Bivouac Creek (6%; p < 0.05). Mean s u r v i v a l r a t e s of Fo r f a r (16%) and Gluskie (28%) creeks were intermediate (p < 0.05), and a l l 3 creeks had lower mean s u r v i v a l r a t e s than Kynock Creek (60%; p < 0.05; Appendix B). There 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 m o r t a l i t y r a t e between the developmental stages (p < 0.01). Eighty percent of the m o r t a l i t y occurred i n the f i r s t 50 days, before h a t c h i n g ( F i g . 6). The 1994 pre-hatch m o r t a l i t y (62.5%) was higher than 1993 (48.1%; p < 0.05). The remaining m o r t a l i t y was expressed as u n f e r t i l i z e d 30 100 j 90 — 80 + F e r t i l i z e d Pre-hatch A l e v i n Pre-emergent f r y Developemental Stage Figur e 6. Percent m o r t a l i t y of embryos assessed at the end of each r e t r i e v a l period f o r a l l study streams combined (mean +/-2*S.E.). Note f e r t i l i z a t i o n = 0-2 days (Aug.), Pre-hatch = 2-50 days ( l a t e Sept.), a l e v i n = 50-180 days ( l a t e Dec. - Feb.), pre-emergent f r y = 180-260 days (mid A p r i l ) . 31 eggs (8%) and over-wintering processes (12%). The ma j o r i t y of over-w i n t e r i n g m o r t a l i t y occurred when i n d i v i d u a l capsules were frozen as i n t r a g r a v e l w a t e r l e v e l s dropped below the capsule depth ( i . e . a s i m u l a t i o n of redd s t r a n d i n g ) . This occurred i n mid-winter when water l e v e l s were lowest. S u r v i v a l rates d i d not d i f f e r between the redd s i m u l a t i o n bags (n=10) and a s s o c i a t e d egg capsules ( f i g . 7 ; p > 0 . 0 5 ) . The redd s i m u l a t i o n bags appeared to show l e s s v a r i a b l e s u r v i v a l among study s i t e s than i n d i c a t e d by the capsule data. F e r t i l i z a t i o n success, determined 48 hours p o s t - f e r t i l i z a t i o n , d i d not vary between years (p > 0 . 0 5 ; F i g . 6 ) . Results of the stream f i d e l i t y experiment were n o n - s i g n i f i c a n t , i n d i c a t i n g that any genetic d i f f e r e n t i a t i o n between creeks does not impair a b i l i t y of eggs to surv i v e i n nearby creeks. Physical Environment A l l i n c u b a t i o n environments were r e l a t i v e l y i n v a r i a n t , w i t h h i g h q u a l i t y i n c u b a t i o n h a b i t a t a v a i l a b l e at a l l s c a l e s examined. Figur e 8 i l l u s t r a t e s the v i s u a l c h a r a c t e r i s t i c s a s s o c i a t e d w i t h r e p r e s e n t a t i v e marginal and p r e f e r r e d i n c u b a t i o n h a b i t a t s . There 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 these h a b i t a t s ( a l l reaches, creeks and years combined) i n e i t h e r stream or i n t r a g r a v e l parameters (Table 2 ) . While both i n c u b a t i o n h a b i t a t s c o n t a i n high q u a l i t y c o n d i t i o n s , there was a trend towards lower values w i t h i n the marginal h a b i t a t s ( i . e . shallower, lower v e l o c i t y , f i n e r s u b s t r a t e , lower p e r m e a b i l i t y , and lower d i s s o l v e d oxygen). 32 > •rH > u 10 100 J 90 80 70 60 50 40 -30 -20 10 + 0 • Simulated Redd - Upper 95% C.I • Mean capsule - Lcwer 95% C I . FLH FLL KLS1 Location KHH KHL Figur e 7. Comparison of s u r v i v a l r a t e ( f e r t i l i z a t i o n to pre-hatch embryos; 50 days) between redd s i m u l a t i o n bags (n=10) u t i l i z i n g r e p r e s e n t a t i v e in situ s u b s t r a t e composition and standard egg inc u b a t i o n capsules (mean +\- 95% confidence i n t e r v a l ) . Incubation l o c a t i o n s were arrayed across study creeks (FLH = F o r f a r 150m p r e f e r r e d redd s i m u l a t i o n . FLL = Fo r f a r 150m marginal. KLS1 = Kynock 350m stranding s i m u l a t i o n . KHH = Kynock 1550m p r e f e r r e d . KHL = Kynock 1550m marginal.) . 33 CD U 4-) CD U 0 • H 4-> a 0 d) Xi TJ a CO ,G CO OJ4J m cd rH 4J tn-H 0 £ | 4J cd 0 Xi x: ch G 0 • - H CO 4J c ro 0 X ! • H 3 4-) O cd G rH - H 6 TJ - H CD CQ rH rH CD T3 4H CD <D rH rH a • o -LO T3 c H G 0 — rd •H 4J T f rH ro CD m N xi a - H CQ - H rH rH f J l - H CD U 4J 4-) rd rH rd e <D 14-i rH (0 4J CD CQ 5 MH 0 0 0 a 1—1 rH CO X rd Sh a) u tti (D - H T3 u a 4J rH rH rrj co G 4H G CD rH 0 ^ 0 - H rd fa 4J 4J • H • T) CD CD c rH 0 0 CD O rH Fig ro Table 2 . Summary of stream and i n t r a g r a v e l p h y s i c a l parameters f o r pr e f e r r e d and marginal redd simulations ( a l l l o c a t i o n s , creeks and years combined; n=25). CAPSULE INCUBATION SITE VARIABLE PREFERRED MARGINAL p < 0.05 VELOCITY (m/s) 0.19 0.13 Std. Err. 0.02 0.04 no Range 0.00 - 0.45 0.0 - 0.71 n 22 21 DEPTH (cm) 29.1 20.7 Std. Err. 4 3.7 no Range 2.0 -74.0 1.0-57.0 n 24 23 STREAM TEMP (C) 3 . 58 3.4 Std. Err. 0.65 0.63 no Range - 0.1-9.4 -0.1-8.8 n 25 24 SURFACE SUBSTRATE 3 .41 3.06 Std. Err. 0.22 0.3 no Range 1.0 - 4.4 1.0-5.0 n 18 18 STREAM DISSOLVED OXYGEN (mg/1) 11.68 11.17 Std. Err. 0.17 0.29 no Range 10.3-13.1 7.3-12.9 n 25 23 INTRAGRAVEL DISSOLVED OXYGEN (mg/1) 10.76 9.99 Std. Err. 0.22 0.4 no Range 8.2-12 .4 4.9-12 .0 n 25 24 PERMEABILITY (ml/s) 21.7 19.3 Std. Err. 2.8 3.7 no Range 8.4-50.0 0.0-48.6 n 16 16 INTRAGRAVEL TEMPERATURE (C) 3.6 3.42 Std. Err. 0.65 0.62 no Range - 0.1-9.4 0.0-8.5 n 25 24 35 The F o r f a r Creek thermal regime i s r e p r e s e n t a t i v e of the annual p a t t e r n f o r n a t a l streams used by the e a r l y S t u a r t sockeye stock ( F i g 9; B. Anderson, D.F.O., P.B.S., unpubl. d a t a ) . D a i l y stream temperatures r i s e from 4 - 10°C during June, vary from 8 -16°C during summer, and drop r a p i d l y i n October and remain at 0.0 -0.5°C throughout winter. Kynock Creek mean spawning p e r i o d temperatures (J u l y 20 - Aug 20 ), ( 11.7 1 9 9 3/13 . 4 1 9 9 4°C) were «1.0°C higher than e i t h e r G l u s k i e (10.2/12.4°C) or F o r f a r (10.5/12.4°C) creeks ( F i g . 10) . The 1994 mean spawning temperatures were s i g n i f i c a n t l y higher than 1993 (p < 0.05). There were no s i g n i f i c a n t d i f f e r e n c e s i n stream temperature between e i t h e r ; 1) reaches w i t h i n a creek or, 2) h a b i t a t type. For a l l reaches, creeks and years combined, there were no s i g n i f i c a n t d i f f e r e n c e s i n i n t r a g r a v e l water temperature between i n c u b a t i o n l o c a t i o n s (Table 2), or h a b i t a t types i n general (Table 3). During the mid-winter (1993) sample p e r i o d , the i n t r a g r a v e l thermal regime c l o s e l y p a r a l l e l l e d (Mean d i f f. = 0.1°C) the stream thermal regime. No h a b i t a t s p e c i f i c groundwater u p w e l l i n g was d e t e c t a b l e from temperature comparisons. Peak stream flows were generated by snow melt d u r i n g the s p r i n g and by r a i n storms during the s p r i n g and autumn. Low flows were observed from November to March and from mid-July to mid-September ( F i g 11; Scrivener and Anderson 1994) . Winter discharges may be as l i t t l e as 20% of the f a l l . As seen from the stream wetted surface area approximately 50 days a f t e r spawning, redds located i n stream margin h a b i t a t s were s u s c e p t i b l e 36 3 1 o c o u CD pa CTl O CTl CTi T3 O - H u CD a CD x; S-l o CD CD 03 VH o CO • CD — u cd 2 4-) 4_> cd cd V-( CD • D j r H CD - 3 J-> a cr £ I 3 e . - H . g pq - H cd * p ^ CTl CD Q r4 tn • H fa 20-J u l 1-Aug 5-Aug 9-Aug 13-Aug 17-Aug C. Gluskie 17 -16 -15 -G 14 -£ 13-ii 1 2 -a e <" 11 -E-10 -20- 24- 28- 1- 5- 9- 13- 17-J u l J u l J u l Aug Aug Aug Aug Aug Figure 10. Early Stuart spawning period (20 July - 20 August) d a i l y maximum stream temperatures i n ; a) Kynock, b) Forfar, and c) Gluskie creeks for the broodyears 1993 and 1994 (B. Anderson, D.F.O., P.B.S., unpubl. data). 38 Table 3. Summary of stream and i n t r a g r a v e l p h y s i c a l parameters by general h a b i t a t type (margin, thalweg, p o o l , off-channel) f o r a l l seasons (1993-1994), creeks (n=4) and l o c a t i o n s combined (n=563). VARIABLE MARGIN THALWAG POOL OFF - CHANNEL P < 0.05 VELOCITY (m/s) 0.29 0 .43 0.14 0.08 * * * Std. Err. 0 .02 0.02 0.01 0.01 Range 0.01-1.06 0.00-1.45 0.00-0.58 0.00-0.59 n 166 187 90 100 Duncan B A C D DEPTH (cm) 18.9 27 . 5 41.8 25.3 * * * Std. Err. 1 1.1 1.9 2 Range 3.0-64.0 2.0-100.0 2.0-84.0 1.0-132.0 n 168 190 92 98 Duncan C B A B STREAM TEMPERATURE (C) 6.7 6.6 5.9 5.8 Std. Err. 0.3 0.3 0.4 0.4 Range -0.1-12.7 -0.1-12.7 -0.1-12.7 -0.2-12.9 n 171 194 93 98 INTRAGRAVEL TEMPERATURE (C) 6.7 6.6 6 5.7 Std. Err. 0.2 0.3 0.4 0.4 Range -0.1-12.8 0-12.8 -0.1-12 .7 -0.1-12.8 n 172 193 93 98 SURFACE SUBSTRATE 3.57 3 .99 3.38 2.84 Std. Err. 0 .07 0 .05 0.16 0.11 Range 1.7-5.1 2.0-5.0 1.0-5.2 1.0-5.0 * * * n 164 184 73 82 Duncan B A B C STREAM DISOLVED OXYGEN (mg/1) 10.9 11 11.1 10.4 Std. Err. 0.1 0.1 0.1 0.2 Range 9.4-13.3 9.4-13.2 9.1-12.8 3.6-13.0 * * * n 171 194 93 98 Duncan A A A B INTRAGRAVEL DISOLVED OXYGEN (mg/1) 9.5 9.8 9.9 6.6 Std. Err. 0.17 0.15 0.2 0.38 Range 0.3-12.8 0.3-12.9 0.3-12.4 0.2-12.0 * * * n 172 193 93 98 Duncan A A A B PERMEABILITY (ml/s) 25.4 25.9 24.9 19.9 Std. Err. 1.5 1.5 2.5 1.8 Range 3-125 4-129 6-120 0-82 n 160 181 60 78 39 o to 6 + r3 o O LL 4 4 LU 2 CC U) 0 AVG FLOW PRECIP. 4^  40 • T N D J F M A M J J A S O DAYS OF 1991-1992 F i g u r e 11. Hydro-meteorological data recorded i n G l u s k i e Creek watershed i n c l u d i n g mean d a i l y flows f o r the water-year November 1, 1991 to October 31, 1992 and t o t a l d a i l y r a i n f a l l f o r A p r i l 27 to October 20, 1992. 40 to dewatering ( F i g . 5) . Reach v e l o c i t i e s at t h i s p o i n t ( l a t e September) averaged 30% of those during the spawning p e r i o d , and redd water depths were s i m i l a r l y reduced. Results of the environmental monitoring program are summarized by h a b i t a t type and sample date i n Appendix CL. There were no di f f e r e n c e s i n mean ( a l l sample periods and ha b i t a t types combined) v e l o c i t y , depth, stream temperature, p e r m e a b i l i t y , or i n t r a g r a v e l water temperature between study creeks (p > 0.05; Appendix C2). There were d i f f e r e n c e s i n surface substrate index, stream d i s s o l v e d oxygen and i n t r a g r a v e l d i s s o l v e d oxygen. A l l mean values i n d i c a t e d h i g h q u a l i t y i n c u b a t i o n habitat(Appendix C2) . The 1994 broodyear was s i g n i f i c a n t l y shallower (p < 0.05). This was a t t r i b u t e d to water impoundment as a r e s u l t of beaver a c t i v i t y i n lower watershed reaches i n 1993 ( i . e . pool depth; Appendix C I ) . G e n e r a l l y , surface substrate composition i n d i c e s were > 3.4, corresponding to high q u a l i t y spawning g r a v e l w i t h mean p a r t i c l e s i z e s of (2 mm - 64 mm) . Only off-channel h a b i t a t (substrate composition index = 2.8) had a s i g n i f i c a n t p r o p o r t i o n of s i l t and sands (Appendix CI ) . The range (1.0-5.0) i n d i c a t e s p o r t i o n s of t h i s h a b i t a t contained high q u a l i t y g r a v e l f o r i n c u b a t i n g eggs (Table 3). There were dif f e r e n c e s i n surface substrate composition between reaches (p < 0.05) . Upper l o c a t i o n s were coarser due to i n c r e a s i n g g r a d i e n t s and water v e l o c i t i e s . Broodyear d i f f e r e n c e s were a t t r i b u t e d to water impoundment by beavers during the w i n t e r of 1993/1994 i n 2 of the 6 study reaches. This r e s u l t e d i n surface d e p o s i t i o n of f i n e sediments. 41 A l l h a b i t a t s (table 3) and capsule incubation l o c a t i o n s (Table 2) c o n t a i n mean p e r m e a b i l i t i e s of > 19 ml/s (6,840 cm/hr). Ninety percent of a l l samples (n = 784) of stream and i n t r a g r a v e l d i s s o l v e d oxygen were > 6.0 mg/1 (Fig. 12). There were i n t r a g r a v e l d i s s o l v e d oxygen d i f f e r e n c e s between the two study years ( J u l y and Sept. sampling periods p < 0.05; mean1993=9.59±0.14 mg/1, mean1994=8.49± 0.19 mg/1). This d i f f e r e n c e was a t t r i b u t e d to the higher water temperatures of 1994. I n t r a g r a v e l d i s s o l v e d oxygen l e v e l s between p r e f e r r e d and marginal i n c u b a t i o n h a b i t a t were s i m i l a r (p > 0.05; Table 2). Only o f f - c h a n n e l h a b i t a t had lower i n t r a g r a v e l d i s s o l v e d oxygen (p < 0.05; 6.4 mg/1; Table 3). The variance w i t h i n a study reach demonstrates a l l h a b i t a t s contain areas of high q u a l i t y i n c u b a t i o n h a b i t a t ( F i g . 13). E f f e c t s of Environmental Factors on Incubation Survival M u l t i p l e r e g r e s s i o n a n a l y s i s of embryo s u r v i v a l r a t e s on p h y s i c a l v a r i a b l e s measured at in c u b a t i o n l o c a t i o n standpipes (stream temperature, d i s s o l v e d oxygen, v e l o c i t y , depth, s u r f i c i a l s u b s t r a t e index and, i n t r a g r a v e l temperature, d i s s o l v e d oxygen, p e r m e a b i l i t y ) f a i l e d to detect any s i g n i f i c a n t c o r r e l a t i o n p r e d i c t i o n s (p > 0.05, r 2 = 0.17, n=53). This was a r e s u l t of; 1) s u r v i v a l between p r e f e r r e d and marginal h a b i t a t s were not s i g n i f i c a n t l y d i f f e r e n t and, 2) p r e f e r r e d and marginal h a b i t a t s contained h i g h q u a l i t y incubation h a b i t a t w i t h n o n - s i g n i f i c a n t d i f f e r e n c e s i n environmental c o n d i t i o n s . R e s u l t s of s i m i l a r 42 D i s s o l v e d oxygen (mg/1) Figure 12. Frequency d i s t r i b u t i o n of stream (n=771) and i n t r a g r a v e l (n=784) d i s s o l v e d oxygen measurements w i t h i n the four study streams from the p e r i o d 1992 - 1995. 43 S1 o ]0/2 outside •Temp outside 0/2 inside Temp insi d e 1 1 2 2 2 2 2 3 Habitat type Fig u r e 13. W i t h i n study reach v a r i a t i o n f o r d i s s o l v e d oxygen and temperature f o r the standpipe sampling g r i d of Kynock Creek 1550 m (mid-watershed), 4 A p r i l 1994. Temperature and d i s s o l v e d oxygen were measured at an i n t r a g r a v e l depth of 20 cm. Standpipes were grouped by h a b i t a t c l a s s i f i c a t i o n code (l=thalweg, r i f f l e , 2=margin, 3=pool, g l i d e , 4=off-channel). 44 s u r v i v a l from low d e n s i t y ("marginal") s i t e s , and h i g h d e n s i t y ("preferred") s i t e s , w i t h obvious v i s u a l s u b s t r a t e d i f f e r e n c e s ( F i g . 8), yet s i m i l a r i n t r a g r a v e l conditions (Table 2), suggest the v i s u a l d i f f e r e n c e s were misleading i n terms of a c t u a l i n c u b a t i o n s i t e q u a l i t y . Incubation l o c a t i o n s f o r the 1994 transect study were se l e c t e d r e g a r d l e s s of expected spawner h a b i t a t u t i l i z a t i o n . As a r e s u l t , the range of environmental parameters a s s o c i a t e d w i t h i n c u b a t i o n l o c a t i o n s was expanded. In c l u s i o n of t h i s data w i t h i n 1994 s u r v i v a l rates r e s u l t e d i n a n o n - s i g n i f i c a n t m u l t i p l e c o r r e l a t i o n p r e d i c t i o n (p = 0.06, r 2 = 0.34, n=43) . There was a n o n - s i g n i f i c a n t r e l a t i o n s h i p between i n t r a g r a v e l d i s s o l v e d oxygen and s u r v i v a l rate ( F i g . 14). Transect data suggest i n t r a g r a v e l d i s s o l v e d oxygen does not e f f e c t s u r v i v a l r a t e u n t i l l e v e l s drop below 4.0 mg/1 ( F i g . 15). Spawning sockeye d i d not u t i l i z e h a b i t a t w i t h l e s s than 3.0 mg/1 i n t r a g r a v e l d i s s o l v e d oxygen. Embryos pl a c e d i n these l o c a t i o n s d i d not s u r v i v e and t h i s r e l a t i o n s h i p i s probably not w e l l d e s c r i b e d by l i n e a r r e g r e s s i o n models. M u l t i p l e r e g r e s s i o n a n a l y s i s a l s o i n d i c a t e d a r e l a t i o n s h i p between temperature and embryo s u r v i v a l r a t e . In 1994, Kynock Creek had s i g n i f i c a n t l y higher s u r v i v a l rates (Appendix B) and stream temperatures ( F i g . 10) . Therefore, at a given sampling time i n 1994, the higher s u r v i v a l rates of Kynock Creek were a s s o c i a t e d w i t h warmer temperatures. This r e l a t i o n s h i p was a spurious r e s u l t . Regression a n a l y s i s i n d i c a t e d the d i f f e r e n c e i n m o r t a l i t y patterns f o r 1993 and 1994 was r e l a t e d to the date f e r t i l i z e d i n 1994 45 100 . 00 -r Y = 2.15x +15.67 2 . 00 4 . 0 0 6 .00 8 .00 1 0 . 0 0 D i s s o l v e d O x y g e n ( m g / 1 ) 12 . 00 Figure 14. Linear regression of the 1994 embryo s u r v i v a l rate ( a l l creeks, locations) 50 days a f t e r f e r t i l i z a t i o n on the corresponding intragravel dissolved oxygen (@ 20 cm depth) at the period immediately p r i o r to egg deposition. 46 1 0 0 so A (0 6 0 > 4 0 -I 2 0 A. 4 6 D i s s o l v e d Oxygen (mg/1) 1 0 Figure 15. The 1994 embryo survival rate (%) from the transect experimental reach (Kynock 1550 m s i t e ; Appendix A) 50 days a f t e r f e r t i l i z a t i o n versus the corresponding intragravel dissolved oxygen (@ 20 cm depth) at the period immediately p r i o r to egg deposition. Transect runs from the north bank margin (A) across a r i f f l e and pool into the off-channel habitat (B). 47 ( F i g . 16). The non-random temporal s e l e c t i o n of i n c u b a t i o n s i t e s l e d to a negative r e l a t i o n s h i p between the date of f e r t i l i z a t i o n and the r e s u l t i n g s u r v i v a l 50 days a f t e r f e r t i l i z a t i o n . The temporal sequence of f e r t i l i z a t i o n and capsule i m p l a n t a t i o n was Kynock, F o r f a r , G l u s k i e , and Bivouac creek. Temporal sequence was d i c t a t e d by the order of spawning and maturation w i t h i n spawning streams. This r e l a t i o n s h i p between date of f e r t i l i z a t i o n and s u r v i v a l r a t e was not evident i n 1993 under a s i m i l a r temporal sequence. The negative r e l a t i o n s h i p of 1994 c o i n c i d e s w i t h the p e r i o d when escapement unexpectedly dropped o f f ( F i g . 4) . This r e l a t i o n s h i p was ex e m p l i f i e d w i t h i n Kynock Creek study reaches. Gametes c o l l e c t e d on August 4-6, 2-4 days a f t e r the escapement peak, had some of the highest s u r v i v a l r a t e s ( F i g . 16) . On August 9, 7 days a f t e r the end of the escapement peak, gametes were s t r i p p e d from the few remaining r i p e a d u l t s at the fence. Although these embryos were planted w i t h i n the same l o c a t i o n they had s i g n i f i c a n t l y lower s u r v i v a l rates ( F i g . 16). Embryos c o l l e c t e d on August 9 s u f f e r e d a m o r t a l i t y event at stage 8-10. This c o i n c i d e s w i t h 20-60 ATU 1s or 2-10 days p o s t - f e r t i l i z a t i o n . This m o r t a l i t y event was not evident i n gametes c o l l e c t e d on August 4-6 and incubated w i t h i n the same stream reach. A l e v i n Development and Behaviour Table 4 summarizes the p h y s i c a l c h a r a c t e r i s t i c s of stranded (marginal s i t e s subject to exposure) and c o n t r o l (preferred) in situ redd s i m u l a t i o n s . There was no d i f f e r e n c e i n i n t r a g r a v e l 48 w o ft to dP > — Ifl 100 80 A. 1993 Q in a o •H 4 J (S d) N •U -rH (ti rH Di -H 4-> rH H > PL. •H > u CO 60 4-40 20 0 x X • • X • X X • • XKynock • F o r f a r O G l u s k i e I 6-Aug 7-Aug 8-Aug 9-Aug 10-Aug 11-Aug 12-Aug 13-Aug Date F e r t i l i z e d Figure 16. Mean capsule survival rate (50 days post f e r t i l i z a t i o n ) for f e r t i l i z a t i o n procedures by date f e r t i l i z e d and creek. A. 1993 f e r t i l i z a t i o n batches and corresponding s u r v i v a l rates. B. 1994 f e r t i l i z a t i o n batches and corresponding s u r v i v a l rates. 49 Table 4. Summary of stream and i n t r a g r a v e l p h y s i c a l parameters and corresponding embryo s u r v i v a l rates f o r in situ redd stranding s i m u l a t i o n s and p r e f e r r e d (control) redd s i m u l a t i o n s . Embryos were f e r t i l i z e d and incubation capsules p l a n t e d i n l a t e August. Experiment was terminated i n mid-February under seasonal minima c o n d i t i o n s f o r discharge and temperature. REDD SIMULATION Santple Kynock 1550 m Kynock 300 m For f a r 150 m F o r f a r 1500 m Va r i a b l e Period Stranded p r e f e r r e d Stranded preferred Stranded preferred Stranded p r e f e r r e d con trol con trol control control Intragravel July 9.1 8.7 9.1 8.2 9.4 9.6 9.7 10.1 Dissolved Oxygen Sept 9.2 10.0 9.0 9.5 9.0 9.8 9.6 8.9 (mg/1) Feb **11.3 8 . 5 - - - - **8.6 12.4 Intragravel July 12.8 12 . 5 12.2 12 . 4 10.6 10.6 11 10.3 Temperature Sept 7.7 7 . 5 9.5 9.4 8.3 8.3 9.3 9.2 (deg C) Feb **0.0 0.1 - - - **0.3 0.0 Water Depth July 8 42 12 17 14 10 7 50 Above Substrate Sept 8 32 6 26 2 25 3 27 (cm) Feb -40 *25 -2 *20 -15 *15 -15 •25 Stream July 0.68 0. 40 0.12 0.15 0.42 0.30 0.30 0.55 V e l o c i t y Sept 0.02 0.17 0.02 0.25 0.22 0.09 0.01 0.16 (m/s) Feb 0.00 - 0.00 - 0.00 - 0.00 -Intragravel Depth of Sept - - - - - -Freezing (cm) Feb 40 0 2 0 15 0 20 0 Mean S u r v i v a l (%) Feb 0 /39 64 16/13 60 32/34 32 0/0 2 (Standard/behaviour) Note: unable to r e t r i e v e Gluskie 50 m redd stranding simulation * = v i s u a l estimate **=40 cm deep standpipe September sample perio d =eyed egg (56 days post f e r t i l i z a t i o n ) February sample perio d =alevin (185 days p o s t - f e r t i l i z a t i o n ) 50 d i s s o l v e d oxygen (p>0.05) . Samples taken at a depth of 40 cm (11.3 mg/1, 8.6 mg/1) i n d i c a t e h o s p i t a b l e r e a r i n g environments at depths below the mean redd depth of 20 cm. No c o n t r o l s i t e s were subject to d e s i c c a t i o n or f r e e z i n g (waterlevel above s u r f i c i a l s u b s t r a t e ) . A l l of the str a n d i n g simulations were i n f l u e n c e d by d e c l i n i n g w a t e r l e v e l s . Embryos w i t h i n standard capsules, w i t h i n a stranded redd, s u r v i v e d unless the depth of f r e e z i n g penetrated to the bottom of the capsules (Table 4). The v e r t i c a l d i s t r i b u t i o n of a l e v i n s w i t h i n behaviour capsules i n r e l a t i o n to depth of f r e e z i n g confirms a l e v i n s are responding d i r e c t l y to t h i s stimulus r a t h e r than to some other f a c t o r that might promote b e t t e r s u r v i v a l by moving deeper i n t o the gra v e l ( F i g . 17). Comparison of the estimated hatching i n t e r v a l ( F i g . 18) and stream thermograph (Fig. 9) suggest a l e v i n hatching coincides with the mean time of the f a l l freeze-up. Spawning c o i n c i d e s w i t h maximum annual stream temperatures and i n c u b a t i n g embryos r a p i d l y accumulate thermal u n i t s e a r l y i n development. As a r e s u l t 67% of the thermal u n i t s are accumulated w i t h i n the f i r s t 19% of the i n c u b a t i o n p e r i o d ( F i g . 18) . Hatching was estimated to occur between Sept 27 - Oct 29. Embryonic stage i n l a t e September ranged from stage 24 (primordial caudal f i n , 3/4 yol k sac vascularized) to stage 30 (hatched a l e v i n ) . The range of thermal u n i t s at t h i s point was 372-436. By e a r l y December, during the onset of minimum temperatures and flows, 100% of embryos had reached the a l e v i n stage (stage 31-35). Coinciding with r i s i n g stream temperatures i n spring, f r y emergence occurs p r i n c i p l y from m i d - A p r i l to mid-May 51 0-15 14 Freezing 15-27 27-3E a Q 38-50 50-61 • A l e v i n s (Feb.) SEggs (Sept) 20% 40% 60% 80% 100% B. u 0-15 15-27 27-38 xi -u) a S 38-50 50-61 203 Freezing 40% 60% 100% C . 0-15 15-27 27-38 a a 38-50 50-61 20% 40% 60% Freezing 30% 1003 Percent t o t a l larvae F i g u r e 17. I n t r a g r a v e l p a t t e r n of changes i n v e r t i c a l d i s t r i b u t i o n of sockeye a l e v i n s i n r e l a t i o n to depth of f r e e z i n g . A. 2 cm depth of f r e e z i n g w i t h i n substrate. B. 15 cm. C. 40 cm. 52 "4-1 CO C D o o c 0 g> o E • i • • • • t> O \ *. \ CO \ c • *. ii '*. V - § » _i_ Period tage 30 • *• *• *• +-" » * . U j irer-oea-I S Zl e se 91 L LZ I 6 xe ex •f -9Z CO • Z,X qj Q oea-8 A O N - 6cT 0Z X X Z \Z 4 0 0 - 5 1 4 0 0 - 9 des-£cT d e s - 8 X h d a s - 6 X G ZZ ex i7 A O N -A O N -A O N -3 0 0 -6nv-6nv-6nv-{ 6nv-<T5 CD as 4-) CO 3 4-) 3 o 4 J 4-> CD 4J <u -r1 g a! ft ft 5 CD I •a H U> W r ; U E-" O ) « O 4-4 T3 CU > CD o ° co • 4-) CO CO r V CD r H CD (XJ 3 o, > t H - rH U CQ CO 4J 4-> CD CD g 6 CD ft O O CD - H Q CD l > X 5 CD - H -a Q s a CTJ CD 4-) CD H CT3 r Q ^ S * M C D -CP -3 . 4_> CT> h H H ft^ 3 CD XI ^ f ) X J 3 w ! ! l "5 ft ^ H C 3 cu nj ft1*-1 CD O 4_> &4 CD 4J 5-1 cd CD J - H • a O * 1 1 U-l r4 O 4 J CD r-l CO O CD -; j 6 ~ 4-> Q r ^ . " H ^ a ^ CO 2 4-> CO e CD 4-> CO > 1 CO s u C u o u CD •a < (5 « 6 CD " H r H M-l CO w 2 ^ e , H u o (0 sAep eaa6ep) s4Tun iBuuam CD U e O CD U r C H 4-4 M-4 4_> fa 53 a f t e r exposure to 600-800 thermal u n i t s (mean = 260 days). 54 CHAPTER 4 - DISCUSSION The stock concept of "unique" salmon "races" ( L a r k i n 1972, Ri c k e r 1973) i s important to management of P a c i f i c salmon, and the Fraser R i v e r sockeye are composed of a multi t u d e of l o c a l spawning stocks ( K i l l i c k 1955, Gilhousen 1960, Cass 1986). While we know very l i t t l e about the genetic composition of the i n d i v i d u a l spawning stocks, i t i s widely b e l i e v e d that d i f f e r e n c e s i n rep r o d u c t i v e and developmental b i o l o g y among pop u l a t i o n s must r e f l e c t adaptations to the s p e c i f i c environmental c o n d i t i o n s experienced during spawning and development ( M i l l e r and Brannon 1982, Brannon 1987, Beacham and Murray 1989, 1990, Murray and McPhail 1988, Murray et. a l . 1989, 1990). Developing an understanding of how i n c u b a t i n g embryos s u r v i v e through seasonal v a r i a t i o n i n temperature and hydrologic regime was a p r i o r i t y of t h i s p r o j e c t . Observed s u r v i v a l r a t e s were f a c i l i t a t e d by; 1) spawning a d u l t s s e l e c t i n g i n c u b a t i o n m i c r o h a b i t a t to optimize egg to f r y s u r v i v a l and, 2) a number of general mechanisms which would optimize i n c u b a t i o n success i n northern environments. These mechanisms i n c l u d e d ; the e a r l y time of spawning, thermal tolerance, development r a t e , a l e v i n b e h a v i o r a l mechanisms, and h a b i t a t m o d i f i c a t i o n s by spawning a d u l t s . I w i l l d i s c u s s those c h a r a c t e r i s t i c s of the environment and p o p u l a t i o n which d i r e c t l y r e l a t e to i n c u b a t i o n s u r v i v a l i n northern environments. I r e j e c t the ant h r o p o c e n t r i c view that northern i n c u b a t i o n streams are a harsh and u n f o r g i v i n g i n c u b a t i o n 55 environment and that prophylactic measures ( i . e . spawning channels) are necessary to m i t i g a t e over-winter m o r t a l i t y . S p a t i a l preferences Micro-Habitat Although the environment u l t i m a t e l y determines i f a f e r t i l i z e d egg w i l l s u r v i v e to produce a f r y , the opportunity to s u r v i v e may be i n f l u e n c e d by the behaviour of the parents. Of s p e c i a l s i g n i f i c a n c e i s the d i s t r i b u t i o n of spawners on the spawning beds. P r e f e r r e d h a b i t a t was the downstream ends of pools at the pool r i f f l e i n t e r f a c e . Numerous studies have p r e v i o u s l y documented t h i s h a b i t a t preference f o r salmonids (Stuart 1953, Hunter 1959, Cooper 1965, Vaux 1968, Hoopes 1972, Tautz and Groot 1975, R e i s e r and Wesche 1977, Thurow and King 1994). Marginal h a b i t a t s which were u t i l i z e d to a l e s s e r degree included; r i f f l e s , stream margins, i n t e r m i t t e n t side channels and portions of the off-channel h a b i t a t . Sockeye s u c c e s s f u l l y spawned over a wide range of h a b i t a t s . This range l i k e l y has upper and lower l i m i t s beyond which f i s h were u n w i l l i n g to spawn as observed from the lack of spawning i n ha b i t a t where i n t r a g r a v e l d i s s o l v e d oxygen l e v e l s were below 3.0 mg/1. Based on the l i n e a l d i s t r i b u t i o n of spawning a d u l t s and t h e i r corresponding micro-habitat parameters, few l o c a t i o n s i n the lower and mid-watershed reaches contained these "zones of e x c l u s i o n " ( T s c h a p l i n s k i 1994) . 56 Distribution on the spawning grounds Due to the f o r t u i t o u s timing of t h i s study a high density year (3.46 spawners/m2) was followed by a very low d e n s i t y year (0.30 spawners/m2) . In 1993, during h i s t o r i c high escapements, there were much higher l o c a l spawning d e n s i t i e s i n p r e f e r r e d and marginal h a b i t a t s . However, the poor q u a l i t y h a b i t a t s ( i . e . d i s s o l v e d oxygen <3.0 mg/1) were g e n e r a l l y not u t i l i z e d f o r spawning even i n t h i s s i t u a t i o n . Instead, a l a r g e r s c a l e s p a t i a l r e - d i s t r i b u t i o n of spawners occurred. F i r s t , ranges w i t h i n the creeks were expanded to l i m i t s imposed by upstream obstructions. This r e s u l t e d i n estimated escapement c a p a c i t i e s (Langer et. a l . 1992), being met or exceeded. Secondly, spawner escapement estimates of a l t e r n a t i v e t r i b u t a r i e s reached unprecedented l e v e l s ( i . e . Bivouac, Leo c r e e k s ) , and were w e l l beyond p r e v i o u s l y described ranges w i t h i n most other n a t a l streams (G. Smith, D.F.O., Stock Assessment Group, per. comm.). This escapement r e - d i s t r i b u t i o n i n dominant c y c l e years was a p r e v i o u s l y noted phenomenon of the e a r l y Stuart stock ( J . Woodey, D.F.O., per. comm, Langer et. a l . 1992) and Alaskan sockeye stocks ( B l a i r and Quinn 1991). The o v e r - r e p r e s e n t a t i o n of escapement to the study streams i n d i c a t e spawners are p r e f e r e n t i a l l y s e l e c t i n g these streams. R e s u l t s from the gamete t r a n s p l a n t experiment between study streams suggest t h i s stock was not prevented by s p e c i f i c stream s e l e c t i o n regimes from c o l o n i z i n g other streams w i t h i n the St u a r t / T a k l a watershed. Previous displacement experiments of sockeye from small streams w i t h i n a lake system suggest a t t r a c t i o n 57 to c e r t a i n spawning s i t e c h a r a c t e r i s t i c s and conspecifics on a l o c a l scale, rather than s i t e s p e c i f i c homing ( B l a i r and Quinn 1991) . To summarize, results from this study and the l i t e r a t u r e suggest spawning adults select spawning habitat to optimize egg to f r y s u r v i v a l . Once l o c a l densities reach c e r t a i n l i m i t s the remaining spawners, as predicted by the gradation i n habitat model (Hilborn and Walters 1992) and density-dependent habitat s e l e c t i o n model (MacCall 1990), move on to colonize less densely populated reaches or streams rather than spawn i n unsuitable habitat, or at dangerously high densities on a l o c a l scale. Incubation Survival The s u r v i v a l rate to pre-emergent fry r e f l e c t s the o v e r a l l rigors endured by a given population of developing eggs and alevins and i s a consequence of the severity of the environmental conditions and the adaptability of the f r y (Koski 1975) . The c a p a b i l i t y of these northern i n t e r i o r streams to sustain eggs and alevins from f e r t i l i z a t i o n to pre-emergence was i n f e r r e d from the r e s u l t s using the perforated incubation capsules. These bioassays are designed to indicate the quality of spawning habitat for the embryo and a l e v i n stage of incubation. They do not provide an assessment of the c r i t i c a l stage of alevin to emergent f r y . Mean sur v i v a l rates to pre-emergent f r y of 49% and 28% for 1993 and 1994 respectively, are i n d i c a t i v e of a high q u a l i t y incubation habitat. Productivity, related to density-independent 58 mechanisms, for Kynock, Forfar and Gluskie creeks appears to be very high. Egg to pre-emergent fry survival rates ranged from 16-60%. This compares favourably to pre-emergent f r y s u r v i v a l rates for s i m i l a r studies (Oncorhynchus spp.) i n coastal systems; 0-87% (P h i l l i p s and Campbell 1961), 16-62% (Coble 1961), 3-47% (Scrivener 1988) , and 0-67% (Groot 1989). Other investigators (Hunter 1959, McNeil 1962) reported pre-hatch mortality rates commonly exceeding 90% under natural conditions. Further, the early Stuart stock does not exhibit lower ov e r a l l recruitment rates per spawner than other Fraser River stocks (Walters and Staley 1987, Cass 1989) . Much of the mortality i n spawning beds has been a t t r i b u t e d to the i n a b i l i t y of fry to emerge from the gravel (Koski 1966, 1975, P h i l l i p s et. a l . 1975). Therefore, studies i n which the newly emerged migrant fry are counted as they leave the stream may give a more accurate estimate of fry production within a stream. Survival of Pa c i f i c salmonids to emergence under natural conditions i s highly variable but normally low; coho 23%-27% (Chapman 1965, Koski 1966), chum 6-31% (Cowan 1991), and pink salmon seldom exceed 20% (Hunter 1959, Parker 1962, McNeil 1966). Estimated f r y survival for sockeye salmon also appears low and has ranged from 2 to 25% over a period of several years i n several streams (Fish. Res. Bd. Can. 1956), 11-31% i n Fulton River (Anon 1968), and 8.9 -17.1% i n Meadow Creek (Kokanee, Taylor et. a l . 1972). Concurrent egg to emigrating f r y estimates within the study streams during the two years of t h i s study ranged from 12-48% (G. Smith, D.F.O., Stock 59 Assessment Group, unpubl. data). These egg to f r y s u r v i v a l r a t e s were higher than other sockeye stocks w i t h i n the j u v e n i l e enumeration program (G. Smith, D.F.O., Stock Assessment Group, per. comm.). The combination of high i n c u b a t i o n s u r v i v a l r a t e s , low over-winter m o r t a l i t y r a t e s , and the high f r y production estimates, support the conclusion that these streams are high q u a l i t y i n c u b a t i o n streams. Very o f t e n spawners are too few to occupy f u l l y the a v a i l a b l e spawning area. I t has been argued that areas not used when runs are small have r e l a t i v e l y poor c o n d i t i o n s f o r eggs and a l e v i n s (Hunter 1959) . R e s u l t s from t h i s study do not support t h i s c o n t e n t i o n . The upper Gluskie Creek incubation s i t e was not u t i l i z e d during the low escapement year, yet provided some of the highest s u r v i v a l r ates w i t h i n t h i s creek. M e r r e l l (1962) and McNeil (1968) reported a s i m i l a r phenomenon w i t h pink salmon i n southwestern A l a s k a . Stock recruitment a n a l y s i s a l s o does not support the c o n t e n t i o n that d i f f e r e n t c y c l e l i n e s are s i g n i f i c a n t l y d i f f e r e n t i n p r o d u c t i v i t y (Walters and S t a l e y 1987, Cass 1989, B l a i r and Quinn 1991) . During t h i s study, d e n s i t i e s were an order of magnitude d i f f e r e n t , yet produced s i m i l a r mean egg to emigrating f r y s u r v i v a l r a t e s (Table 1) . The higher f r y production estimates of 1994 appears to co n t r a d i c t that of the pre-emergent s u r v i v a l estimates. I speculate that the higher e a r l y ' m o r t a l i t y rates observed w i t h i n i n c u b a t i o n capsules were compensated f o r by a dramatic decrease i n sup e r i m p o s i t i o n at the much lower spawner d e n s i t i e s of 1994. 60 E f f e c t s of Environmental Factors on Incubation Survival S u r v i v a l r a t e s between p r e f e r r e d and marginal h a b i t a t s were not s i g n i f i c a n t l y d i f f e r e n t i n contrast to p r e d i c t i o n s generated from o p t i m a l i t y models ( F r e t w e l l and Lucas 1970, MacCall 1990, H i l b o r n and Walters 1992) . This was due to the p e r c e p t i o n and d e f i n i t i o n of "marginal" h a b i t a t . T r u l y marginal areas ( i . e . < 3.0 mg/1 d i s s o l v e d oxygen) were avoided by spawning a d u l t s . The r e s u l t was low d e n s i t y ( i . e . assumed marginal) and h i g h d e n s i t y ( i . e . assumed preferred) in situ redd s i m u l a t i o n s w i t h s i m i l a r i n t r a g r a v e l c o n d i t i o n s . Temperature and Embryo Development The f i r s t h a b i t a t l i m i t a t i o n of concern was maximum stream temperatures during spawning. Mean stream spawning p e r i o d temperatures ranged from 10.2 - 13.4°C. I n t r a g r a v e l temperatures c l o s e l y f o l l o w e d these values. While mean spawning p e r i o d temperatures were below maximums r e f l e c t e d i n the l i t e r a t u r e f o r s u c c e s s f u l spawning and f e r t i l i z a t i o n , d a i l y maximum temperatures approached 16°C i n Kynock Creek i n 1994. M o r t a l i t y was not s i g n i f i c a n t l y r e l a t e d to spawning p e r i o d temperatures. Contrary to expectations the highest s u r v i v a l rates were a s s o c i a t e d w i t h the highest temperatures. The second l i m i t a t i o n of concern was o v e r - w i n t e r i n g egg m o r t a l i t y due to f r e e z i n g and dewatering. Stream temperatures d e c l i n e d to mid-winter lows of 0°C f o r s e v e r a l months, and water l e v e l s d e c l i n e d to «20% of spawning period (Scrivener and Anderson 61 1994) . However, the m a j o r i t y of m o r t a l i t y (80%) occurred before the onset of winter c o n d i t i o n s , and only 12% of embryo m o r t a l i t y occurred from 10 Oct - 15 A p r i l ( F i g . 6) . These r e s u l t s conform to p a t t e r n s d e r i v e d f o r Oncorhynchus spp. from c o a s t a l and l a b o r a t o r y systems (Wickett 1954, A l d e r d i c e e t . a l . 1958, Hunter 1959, McNeil 1962, Murray and McPhail 1988, Beacham and Murray 1989). This suggests over-winter m o r t a l i t y due to f r e e z i n g and d e s i c c a t i o n was not determining f r y production as o r i g i n a l l y hypothesized. The c h a r a c t e r i s t i c signature of groundwater u p w e l l i n g i n a northern environment i s a warmer, more stable winter thermal regime w i t h i n the i n t r a g r a v e l environment (Sheridan 1962, Cooper 1965, Leman 1993). Where i n t r a g r a v e l water temperatures d i f f e r only a small amount from the stream, the major source of i n t r a g r a v e l d i s s o l v e d oxygen i s the interchange of that water w i t h surface flow (Sheridan 1962, Cooper 1965). Study streams were i n d i c a t i v e of high interchange between stream and i n t r a g r a v e l environment. This i n d i c a t e s the i n c u b a t i o n environment i s maintained by the stream and not u p w e l l i n g groundwater. Therefore, spawning salmon were not s e l e c t i n g incubation, s i t e s based on temperature ( i . e . u p w e l l i n g groundwater to maximize embryo s u r v i v a l r a t e ) . In the case of f a l l spawners the embryos must reach some c r i t i c a l stage of development before the water becomes to c o l d (Brannon 1965). Results from Combs and Burrows (1957) and Combs (1965) suggest that pink and Chinook embryos could t o l e r a t e long periods of low temperatures i f the i n i t i a l temperature was above 6.0°C and embryogenesis had proceeded to a c r i t i c a l developmental 62 stage. The early Stuart stock spawns four weeks e a r l i e r than any other Fraser River stock ( K i l l i c k 1955, Brannon 1987), allowing incubating embryos to rapidly accumulate thermal units and reach t h i s c r i t i c a l stage p r i o r to winter "freeze-up". Results i n experimental channels and simulated redds indicate eggs can tolera t e 1-5 weeks dewatering with no e f f e c t s on hatching success, provided moisture content i s maintained and the sediments neither freeze nor exceed incubation tolerances (Fast et. a l . 1982, Becker et. a l . 1983, Reiser and White 1983, N e i t z e l and Becker 1985, Becker et. a l . 1986). Newly hatched alevins, however, are intolerant due to the formation of functional g i l l s (Becker et. a l . 1982). By spawning e a r l i e r than any other sockeye stock the early Stuart adults ensure embryos experience a rapid early development phase and are undergoing the c r i t i c a l hatching phase as freeze-up descends upon the region. Salmonid alevins move about both l a t e r a l l y and v e r t i c a l l y within the gravel bed p r i o r to emergence, and changing environmental conditions may affe c t subgravel behaviour (Stuart 1953, D i l l 1967, 1969, Bams 1969, D i l l and Northcote 1970, Carey and Noakes 1981, Godin 1982, Fast et. a l . 1982, Garcia De Leaniz et. a l . 1993). Frequent movement, i n favourable substrata, of 5 cm/min has been recorded (Bams 1969). The observed downward migratory response of sockeye alevins to freezing (Fig. 17) i s an adaptation to the incubation environment. This mitigates the apparent harshness of i n t e r i o r streams. Laboratory re s u l t s u t i l i z i n g early Stuart broodstock duplicated these in situ 63 r e s u l t s (Dr. M. Bradford, D.F.O., Research D i v i s i o n , per. comm.). Directed movement was found under temperature stress, but not i n controls, confirming that alevins are responding to temperature. This response was not observed i n coastal Chinook alevins i n d i c a t i n g either: 1) There was an int e r a c t i o n between substrate s i z e and a l e v i n size which allowed the sockeye alevins to migrate and not the larger chinook. 2) There i s a genetic determinant of behaviour, which the coastal chinook alevins lacked. Gravel Quality and Dissolved Oxygen Numerous studies have led to consensus that low dissolved oxygen and reduced water exchange increase embryo mortality. V a r i a t i o n due to other factors often obscures t h i s r e l a t i o n s h i p i n natural systems, such that survival often appears independent of intragravel dissolved oxygen (Koski 1966, Chapman 1988, Groot 1989, Vronskii and Leman 1991) . Hansen (1975) found streambed areas with low dissolved oxygen (< 3.0 mg/1) were not used for spawning. Ninety percent of the intragravel dissolved oxygen values within t h i s study were > 6.0 mg/1. Those areas below 3.0 mg/1 were not u t i l i z e d for spawning. As a result, i t should not be su r p r i s i n g to f i n d there was not a s i g n i f i c a n t r e l a t i o n s h i p between intragravel dissolved oxygen and sur v i v a l . Survival of salmonid embryos has been related to substrate composition i n many experiments and f i e l d studies (Koski 1966, 1975, Tappel and Bjornn 1983, Tagart 1984, Scrivener and Brownlee 1989, L i s l e and Lewis 1992, Hall and Lantz 1969, D i l l and Northcote 64 1970) . High i n t r a g r a v e l d i s s o l v e d oxygen and s u r v i v a l r a t e s have o f t e n been a t t r i b u t e d to high p e r m e a b i l i t i e s (Coble 1961, Wells and McNeil 1970, Wickett 1970). P e r m e a b i l i t y does not a f f e c t s u r v i v a l d i r e c t l y but i s a measure of the adequacy of the gravel i n the redd to a l l o w f o r a s u f f i c i e n t supply of water and d i s s o l v e d oxygen to the embryos and f r y . The spawning female can a l t e r g r a i n s i z e and p o r o s i t y of gravel to ensure that ova begin with an adequate flow of oxygenated water (Chapman 1988) . Vigorous digging of the female removes f i n e s and small g r a v e l s to form the egg pocket and the completed redd contains l e s s f i n e s i l t and sand than the surrounding s u b s t r a t e (McNeil and A h n e l l 1964, R i n g l e r 1970, Everest e t . a l . 1987, Chapman 1988) . Substrate p e r m e a b i l i t i e s w i t h i n the study streams c l o s e l y agree w i t h values documented by Chapman (1988) f o r heavy spawning g r a v e l beds of optimal s u r v i v a l c o n d i t i o n s . Concurrent s t u d i e s by other researchers demonstrate that p a r t i c l e s < 0.3 mm i n diameter were rare (1-1.6%) and i n t e r s t i t i a l spaces i n the g r a v e l would remain c l e a r p e r m i t t i n g water exchange and movement of a l e v i n s (Scrivener 1994). The lowest mean p e r m e a b i l i t i e s at the completion of the incubation period were > 19 ml/s (Table 3). Koski (1966) reported no detectable a f f e c t on s u r v i v a l above t h i s t h r e s h o l d . Egg to f r y s u r v i v a l rates of > 30% are expected from such g r a v e l s (Lotspeich and Everest 1981, Sc r i v e n e r and Brownlee 1989, Chapman 1988, Scrivener 1994). Large annual spawning populations of P a c i f i c salmon probably engender a "mass cle a n i n g " and help maintain h i g h q u a l i t y spawning 65 h a b i t a t (Everest e t . a l . 1987, Chapman 1988, Burgner 1991). Annual s c a r i f i c a t i o n of flow c o n t r o l l e d spawning channels i s a commonly used remedial measure to mimic t h i s e f f e c t (Taylor e t . a l . 1972). Using independent methods, Scrivener and Anderson (1994) and G o t t e s f e l d (1994), estimated spawning salmon w i t h i n the study streams accounted f o r 25-50 % of the annual movement of bed m a t e r i a l . During salmon spawning, o v e r - r e p r e s e n t a t i o n of f i n e sediments (<1.19mm) i n bedload movement, i n c o n j u n c t i o n w i t h a suspended sediment concentration peak, suggest spawners were measurably i n f l u e n c i n g the p a r t i c l e s i z e d i s t r i b u t i o n of the streambed (Scrivener and Anderson 1994). I t i s p o s s i b l e that over the course of a number of years the geomorphic work done by spawning sockeye i s comparable to or even g r e a t e r than that performed by floods ( G o t t e s f e l d 1994). I n t e r i o r systems have low autumn and wi n t e r stream flows. These flows are unable to transport bedload and do not form a l a y e r i n g p a t t e r n l i k e c o a s t a l systems, where spawning takes place as autumn and winter f r e s h e t s are e s t a b l i s h i n g l a y e r i n g p a t t e r n s (C. Scrivener, D.F.O., Research D i v i s i o n , per. comm.). As a r e s u l t , i n t e r i o r spawning sockeye salmon have a l a s t i n g impression on the streambed c h a r a c t e r i s t i c s . Stress Production of f r y under optimal c o n d i t i o n s ( i . e . a r t i f i c i a l spawning channels) i s not constant from year to year or from stream to stream, and the differences often remain unexplained. A c r i t i c a l 66 question of sockeye salmon po p u l a t i o n b i o l o g y i s the r e l a t i v e importance of s t r e s s f a c t o r s encountered by spawners p r i o r to spawning, versus s t r e s s f e l t by embryos due to the environmental c o n d i t i o n s experienced during i n c u b a t i o n . . The e a r l y Stuart stock enters the Fraser R i v e r from l a t e June through m i d - l a t e J u l y at a time when r i v e r temperatures are r i s i n g and the flows are near t h e i r peak (Clarke e t . a l . 1994). This combination of high temperatures and high streamflow d u r i n g the m i g r a t i o n p e r i o d can place severe demands on energy reserves, r e s u l t i n g i n the u t i l i z a t i o n of 90-95% of body f a t reserves and 55-60% of p r o t e i n reserves ( I d l e r and Clemens 1959) . The i n c u b a t i o n capsule r e s u l t s i n 1994 demonstrate a negative r e l a t i o n s h i p between date f e r t i l i z e d and s u r v i v a l r a t e . Furthermore, embryos w i t h i n the same l o c a t i o n (Kynock 300 m) had very d i f f e r e n t s u r v i v a l rates based on the date gametes were s t r i p p e d and f e r t i l i z e d . This i n d i c a t e s a p o s s i b l e d e t e r i o r a t i o n of gamete v i a b i l i t y . This r e l a t i o n s h i p c o i n c i d e d w i t h dates when escapement unexpectedly dropped o f f during the second h a l f of the run ( F i g . 4) . Evidence of an e a r l y m o r t a l i t y event i n the l a t e spawned gametes and not the e a r l i e r gametes, i n conjunction w i t h no known change i n p h y s i c a l i n c u b a t i o n c o n d i t i o n s , i n d i c a t e f a c t o r s other than environmental c o n d i t i o n s may have been r e s p o n s i b l e . I t has been hypothesized that the d e c l i n e i n a r r i v a l s was c o i n c i d e n t a l w i t h , and caused by, the extreme temperatures that developed i n the Fraser R i v e r during the 1994 m i g r a t i o n ( F i g . 19; Cl a r k e e t . a l . 1995). The 1994 e a r l y Stuart m i g r a t i o n temperature 67 began s l i g h t l y below average and r a p i d l y rose at peak passage time to reach h i s t o r i c a l maximum l e v e l s . Ocean c o n d i t i o n s set the stage fo r s u c c e s s f u l r i v e r migration (Blackbourne 1991, Mysak 1986, Hinch et. A l . 1994, 1995). A n a l y s i s of weight-length r e g r e s s i o n s (Dr. S. Hinch, U.B.C. F i s h e r i e s Centre, pers. com.) i n d i c a t e d the 1994 e a r l y Stuart sockeye were i n better i n i t i a l c o n d i t i o n than the 1993 broodstock. B i o e n e r g e t i c modelling i n d i c a t e d that energy use i n 1994 was the t h i r d highest recorded w h i l e 1993 was eq u i v a l e n t to the long term average (Clarke e t . a l . 1995). In 1993 79% of r a d i o -tagged sockeye reached H e l l ' s Gate, w h i l e i n 1994 67% a r r i v e d . However, during the second week of J u l y (1994) as temperatures rose r a p i d l y , no f i s h reached H e l l ' s Gate, and f i s h s t i l l downstream d i s p l a y e d e r r a t i c behaviour (Clarke e t . a l . 1995). I t has been demonstrated that elevated water temperatures dur i n g upstream spawning migrations create severe and acute s t r e s s which a l t e r s b e h a v i o r a l and p h y s i o l o g i c a l responses (Johnston e t . a l . 1992). K i l l i c k (1955) demonstrated the c h r o n o l o g i c a l order of sockeye m i g r a t i o n , spawning and death show remarkable c o n s i s t e n c y w i t h i n races. The abrupt disappearance of the t a i l of the run at the spawning grounds supports these f i n d i n g s . The hypothesis that m i g r a t i o n arduousness may a f f e c t progeny s u r v i v a l was i n c i d e n t l y t e s t e d i n t h i s study. The h i s t o r i c a l mean r e c r u i t s per spawner database (1949-1987; Pac. Salm. Comm., unpubl. data) was blocked by 1°C increments of mean J u l y temperature at H e l l ' s Gate. There appears to be an optimum temperature range f o r progeny s u r v i v a l from broodstock mi g r a t i o n at 15-16°C ( F i g . 20). 68 s s * V (' s / ' s a a H H ro en X S (71 CTl w Kt H cn <H 1 s a a i ; rH | 1 j i ! i i 1 CM CN O CN —r— o CO <o ( 0 ) ajn^Bjaduiaj, - Bnv-Si - 6nv-ei - 6nv-II - 6nv-6 - 6nv- Z. - 6nv-5 - 6nv-e - SnY-T - i^r-oe - Tnr-8c3 - inr-9e - I^f-fZ - inr-os - inr-8T - inr-91 - inr-^T - inr-ex - inr-OI - inr-8 - inr-9 - inr-iv - T^C-Z -- unr-0£ 4-1 r H rd - H (13 SH T3 CD > c - H ro CTl CD 6 rH CD <tf GO CTl CO CTl U r H fa CD C £ ! CO 4-> ro g cr, O CTi rH r H 4 H CD 00 xi CD 4_> SH ^ xi J-> 4-) CO - H SH £ CD QHT3 g CD CD 4_) rH CD 4_> CO rH CO It O u C ro rO cr. CD cn g « H CO LD g CT> 3 r H •H g c o - H rH g 4-< - CD g t n 3 co g rH - H CD X > c0 (0 g — • CO >, CD CD r H 4-> rH • H CO 3 CO O 4 J Q co CO rH • - CD cn r H a r H r H g CD CD CD ffi 4-> U D l - H fa 6 3 F i g u r e 20. Mean e a r l y Stuart r e c r u i t s per spawner f o r each one degree c e l s i u s increment of mean J u l y F r a s e r R i v e r water temperature at H e l l ' s gate f o r the p e r i o d 1948 - 1989. R e c r u i t s per spawner c a l c u l a t e d from INPFC sockeye database ( I . W i l l i a m s , D.F.O., P.B.S, unpubl. data) based on returns c a l c u l a t e d from estimated catch plus escapement on a four year r e t u r n c y c l e . Mean J u l y Fraser R i v e r water temperature c a l c u l a t e d f o r each corresponding year from H e l l ' s Gate database. 70 How egg q u a l i t y a f f e c t s embryo s u r v i v a l i s at t h i s p o i n t j u s t c o n j e c t u r e . Advancing temperature above species s p e c i f i c optima duri n g the spawning mi g r a t i o n appears to have an i n h i b i t i n g e f f e c t on gonad development and gamete q u a l i t y i n many salmonid spec i e s . Columbia River sockeye lose an average of 7.5% of t h e i r body weight at 10°C and 12% at 16.5°C. Testes were > 25% smaller at 16.5°C, and adverse gonadal development was evident i n females who produced s m a l l e r and l i g h t e r eggs at 16.5°C (Bouck e t . a l . 1975, Bouck 1977) . In 1977 approximately 6 347 000 eggs were s t r i p p e d from moribund H o r s e f l y females (INPFC 1978). Fry p r o d u c t i o n was estimated at j u s t 0.3% (INPFC 1979), and v i a b i l i t y of the eggs was the suspected cause. Chronic confinement and acute emersion s t r e s s r e s u l t s i n endocrine dysfunctions and s i g n i f i c a n t l y lower s u r v i v a l r a t e s ( f e r t i l i z a t i o n to 28 days posthatch) f o r progeny from s t r e s s e d f i s h compared to progeny from unstressed c o n t r o l f i s h (Campbell e t . a l . 1992, 1994). While the f i s h c u l t u r e i n d u s t r y recognizes that v a r y i n g egg q u a l i t y i s one of the l i m i t i n g f a c t o r s f o r s u c c e s s f u l mass production of f i s h f r y (Piper et. a l . 1982, K j o r s v i k et. a l . 1990), c l a s s i c a l recruitment models (Ricker 1954, Beverton and Holt 1957, recruitment r e g r e s s i o n models) have not e x p l i c i t l y recognized the e f f e c t s of egg q u a l i t y on s u r v i v a l of p o t e n t i a l r e c r u i t s . Such models have g e n e r a l l y assumed that v a r i a t i o n i n r e c r u i t s per spawner must be due to v a r i a t i o n s i n environmental c o n d i t i o n s experienced by the r e c r u i t s , not t h e i r parents. My hypothesis suggests m i g r a t i o n c o n d i t i o n s encountered by a d u l t sockeye i n the 71 mainstem Fraser R i v e r may determine the year c l a s s s t r e n g t h of the progeny. Therefore, egg production and j u v e n i l e environmental c o n d i t i o n s alone cannot be r e l i e d upon as p r e d i c t o r s of r e p r o d u c t i v e success. 72 CHAPTER 5 - CONCLUSION The high p r o d u c t i v i t y , r e l a t e d to density-independent mechanisms, f o r the spawning grounds of these c e n t r a l i n t e r i o r study streams was i n f e r r e d from r e s u l t s using perforated incubation capsules. The combination of high i n c u b a t i o n s u r v i v a l r a t e s , low overwinter m o r t a l i t y rates and the high f r y p r o d u c t i o n estimates, support the con c l u s i o n that these streams are hi g h q u a l i t y i n c u b a t i o n streams. Several f a c t o r s r e s u l t e d i n the la c k of c l a s s i c a l r e l a t i o n s observed i n previous s t u d i e s between i n c u b a t i o n parameters and s u r v i v a l . Observed s u r v i v a l rates were f a c i l i t a t e d by spawning a d u l t s s e l e c t i n g i n c u b a t i o n microhabitat to optimize egg to fry-s u r v i v a l . S u r v i v a l rates between low d e n s i t y and hi g h d e n s i t y spawning h a b i t a t s were not s i g n i f i c a n t l y d i f f e r e n t due to the pe r c e p t i o n and d e f i n i t i o n of "marginal" h a b i t a t . T r u l y marginal areas were avoided by spawning a d u l t s . The r e s u l t was low de n s i t y ( i . e . assumed marginal) and high d e n s i t y ( i . e . assumed preferred) in situ redd s i m u l a t i o n s w i t h s i m i l a r i n t r a g r a v e l c o n d i t i o n s . Incubation environments were r e l a t i v e l y i n v a r i a n t w i t h high q u a l i t y incubation habitat a v a i l a b l e at a l l scales examined. I t was proposed that the r e l a t i v e l y uniform, high q u a l i t y h a b i t a t was due to ; 1) the high q u a l i t y of a v a i l a b l e bedload, of the c o r r e c t dimensions, that moves through these systems at a r a t e that i s modest i n comparison to c o a s t a l systems and, 2) the mass c l e a n i n g engendered by high d e n s i t i e s of spawning a d u l t s . This r e s u l t s i n 73 h i g h q u a l i t y g r a v e l c o n d i t i o n s w i t h p e r m e a b i l i t i e s , s u r f a c e water interchange, and i n t r a g r a v e l d i s s o l v e d oxygen l e v e l s a s s o c i a t e d w i t h h i g h i n c u b a t i o n success. A number of mechanisms to optimize i n c u b a t i o n success i n northern environments were i d e n t i f i e d w i t h i n the e a r l y Stuart stock. E a r l y Stuart sockeye r i s k energy d e p l e t i o n and seasonal maximum temperatures during m i g r a t i o n and spawning. The advantage accrued by spawning e a r l y i n the season i s advanced embryological development p r i o r to the onset of low water temperatures. Embryos r a p i d l y accumulate the thermal u n i t s necessary to hatch, thereby becoming mobile i n time to respond to f r e e z i n g and d e s i c c a t i o n as w a t e r - l e v e l s d e c l i n e . A l e v i n s of the e a r l y S t u a r t stock can apparently t o l e r a t e temperature c o n d i t i o n s p r e v i o u s l y considered l e t h a l f o r long periods of time and emerge s u c c e s s f u l l y a f t e r l e s s thermal u n i t s than any other Fraser R i v e r stock. The trade o f f against t h i s strategy i s the e f f e c t of unusually s t r e s s f u l m i g r a t i o n c o n d i t i o n s on the q u a l i t y and v i a b i l i t y of the gametes. Evidence of t h i s trade o f f was obtained i n 1994 when egg s u r v i v a l rates were very low f o r spawners that a r r i v e d l a t e and had s u f f e r e d severe thermal s t r e s s during m i g r a t i o n . I m p l i c a t i o n s f o r stock management are the general assumption of c l a s s i c a l recruitment models that v a r i a t i o n i n r e c r u i t s per spawner must be due to v a r i a t i o n s i n environmental c o n d i t i o n s experienced by the r e c r u i t s , not t h e i r parents. I m p l i c a t i o n s to h a b i t a t management i n c l u d e ; 1) the seasonal v a r i a t i o n i n temperature and discharge d u r i n g spawning and i n c u b a t i o n and, 2) increases or changes i n the 74 c h a r a c t e r of sediment input. As spawning p e r i o d temperatures approach c r i t i c a l l e v e l s and energy reserves of spawning adults are at a minimum, r i p a r i a n f o r e s t r y p r e s c r i p t i o n s must be c l o s e l y monitored. The apparent adaptation i n developmental b i o l o g y of the e a r l y S tuart stock and the s p e c i f i c t i m i n g to the seasonal v a r i a t i o n i n temperature and h y d r a u l i c regime would suggest monitoring of these v a r i a b l e s i n a s s o c i a t i o n w i t h f o r e s t r y p r e s c r i p t i o n s should be a p r i o r i t y of f u t u r e research. As r i p a r i a n zone su b s t r a t e s are c h a r a c t e r i z e d by l a r g e amounts of l a c u s t r i n e d e p o s i t s p o s t - l o g g i n g increases i n the d e l i v e r y of f i n e sediments must not surpass the a b i l i t y of p h y s i c a l (hydraulic regime, bedload c h a r a c t e r i s t i c s ) and b i o l o g i c a l (mass cleaning by high d e n s i t i e s of spawning adu l t s ) processes to maintain the current g r a v e l q u a l i t y . 75 LITERATURE CITED A l d e r d i c e , D.F. and W.P. Wickett, and J.R. B r e t t . 1958. 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E f f e c t of q u a l i t y of the spawning bed on growth and development of pink salmon embryos and a l e v i n s . U.S. F i s h and W i l d l i f e Service S p e c i a l S c i e n t i f i c Report - F i s h e r i e s 616. Wickett, W.P. 1954. The oxygen supply to salmon eggs i n spawning beds. J . F i s h . Res. Bd. Can. 11: 933-953. Wickett, W.P. 1958. Review of c e r t a i n environmental f a c t o r s a f f e c t i n g the production of pink and chum salmon. J . F i s h . Res. Bd. Can. 15: 1103-1126. Wickett, W.P. 1970. Review of c e r t a i n environmental f a c t o r s a f f e c t i n g the production of pink and chum salmon. J . F i s h . Res. Bd. Canada. 27: 1215-1224. Wilcox, K.W., J . Stoss and E.M. Donaldson. 1984. Broken eggs as a cause of i n f e r t i l i t y of coho salmon gametes. Aquaculture. 40: 77-87. 89 Young, M.K., W.A. Hubert and T.A. Wesche. 1991. Selection of measures of substrate composition to estimate s u r v i v a l to emergence of salmonids and to detect changes i n stream substrates. N. Amer. J. Fish. Manage. 11: 339-346. Zar, J.H. 1984. B i o s t a t i s t i c a l analysis. Prentice H a l l , Englewood C l i f f s , New Jersey. 718p. 90 APPENDIX A Schematic representations of study reaches showing standpipe monitoring s t a t i o n s , egg i n c u b a t i o n s i t e s (redd s i m u l a t i o n s ) , and observed redd d i s t r i b u t i o n . 91 T FLOW i <&> T2 O SCALE (meter*) LEGEND O Permanent Transect Stake • Standpipe Monitoring Station M "Preferred" Habitat Redd Simulation • "Marginal" Habitat Redd Simulation ^ "Stranded " Redd Simulation H Incubation "Bag" Redd Simulation gg£ Gamete Transplant Incubation Site e Transect Incubation Site Observed Sockeye Redd (1993) (gj) Observed Sockeye Redd (1994) Figure A l . Kynock Creek mid-watershed (1550m) study reach showing standpipe monitoring stations, egg incubation sites (redd simulations), and observed redd distribution. Tf. 6j2 LEGEND O Permanent Transect Stake • Standpipe Monitoring Station M "Preferred" Habitat Redd Simulation HI "Marginal" Habitat Redd Simulation $ "Stranded " Redd Simulation H Incubation "Bag" Redd Simulation <S> Observed Sockeye Redd (1993) @ ) Observed Sockeye Redd (1994) L E G E N D o Permanent Transect Stake • Standpipe Monitoring Station m "Preferred" Habitat Redd Simulation • "Marginal" Habitat Redd Simulation § "Stranded " Redd Simulation • Incubation "Bag" Redd Simulation • Gamete Transplant Incubation Site Transect Incubation Site Observed Sockeye Redd (1993) Observed Sockeye Redd (1994) Figure A3. Forfar Creek mid-watershed (1500m) study reach showing standpipe monitoring stations, egg incubation sites (redd simulations), and observed redd distribution. 0-FF-CHANNEI LEGEND O Permanent Transect Stake • Standpipe Monitoring Station PI "Preferred" Habitat Redd Simulation | "Marginal" Habitat Redd Simulation H "Stranded " Redd Simulation fill Incubation "Bag" Redd Simulation (§3) Observed Sockeye Redd (1993) @ ) Observed Sockeye Redd (1994) Figure A4. Forfar Creek lower-watershed (150m) study reach showing standpipe monitoring stations, egg incubation sites (redd simulations), and observed redd distribution. SCALE (meters) j I 95 V TIO T 2 0 S C A L E (meters) L E G E N D El • § 1 Permanent Transect Stake Standpipe Monitoring Station "Preferred" Habitat Redd Simulation "Marginal" Habitat Redd Simulation "Stranded " Redd Simulation Incubation "Bag" Redd Simulation Gamete Transplant Incubation Site Transect Incubation Site Observed Sockeye Redd (1993) Observed Sockeye Redd (1994) Figure A6. Gluskie Creek lower-watershed (50m) study reach showing standpipe monitoring stations, egg incubation sites (redd simulations), and observed redd distribution, (note redd observations were not recorded in 1993. Standpipe monitoring station locations varied between years due to beaver dam.) 9? APPENDIX B Summary of egg to pre-emergent s u r v i v a l r a t e s f o r p r e f e r r e d and marginal redd s i m u l a t i o n s 98 Appendix B l . Summary of mean sur v i v a l rate (n1993=10 , n 1 9 9 4 = 6 -7 capsules per site/time r e t r i e v a l ) f o r incubation habitat type (preferred=high u t i l i z a t i o n , marginal=low u t i l i z a t i o n ) by creek (n=4), lo c a t i o n (upper=mid-watershed, lower=lower watershed), and sample session (developmental stage; l=late September, 2=late December, 3=late April) for selected spawning streams of the early Stuart sockeye stock. Table format r e f l e c t s the nested general l i n e a r models experimental design (SAS 1988). INCUBATION HABITAT BrYr Creek CREEK LOCATION DEVELOP. Preferred Marginal Mean Means STAGE 1993 1994 1993 1994 93 94 93/94 Bivouac Upper 1 - 13.91 - 19.30 2 - 0.00 - 8.36 3 - 0.00 - 0.00 - 7 Lower 1 - 9.85 - 20.14 2 - 0.00 - 0.00 3 - 0.00 - 1.05 - 5 -IQ Gluskie Upper 1 70.65 34.39 74.48 56.14 2 64.46 8.49 63.09 55.46 3 35.06 5.26 62.92 - 61 32 Lower 1 21.55 13.95 60.64 20.20 2 26.06 - 59.78 -3 21.95 - 49.52 - 40 17 51/28 Forfar Upper 1 26.33 3.99 49.30 6.62 2 21.29 1.50 47.00 0.00 3 24.53 1.75 47.58 0.00 36 2 Lower 1 69.76 29.91 62.06 31.97 2 71.04 31.88 67.09 32.32 3 69.50 33.03 40.89 14.12 63 29 50/16 Kynock Upper 1 69.59 61.45 61.33 64.71 2 67.44 63.74 55.34 59.42 3 69.99 59.80 54.91 60.02 63 62 Lower 1 34.40 64.09 22.84 60.44 2 34.16 60.20 21.03 58.61 3 36.26 57.36 21.76 51.76 28 59 46/60 Mean 46 25 51 30 49 27 38 99 APPENDIX C Watershed and Broodyear stream and i n c u b a t i o n p h y s i c a l parameters 100 4 J rd 4J •H X! rO XI CQ U CD 4-) CD e rrj rH rrj CD a •H o, o u rH rd co. u B •H rd CQ CD >i rH a CQ 0) T j > 3 rd 4 J U CQ Cn rd rH rH r H -u rd a •H in O TS 4H a rd T5 O •H rd cu cu CQ CD rH 4H ft o e rd >i CQ u rd TJ 6 CO H 4-J U rd U X -H -H sH Ti -H £ CQ CD CQ ft rd ftrH RELATIVE PERMEABILITY INDEX (ml/s) 39.5 (26.0) 22.7 (18.2) 23.6 (14.5) 23.1 (16.4) 18.6 (12.9) 25.3 (19.4) 35.1 (24.1) 26.1 (19.1) 19.9 (11.7) 23.6 (19.4) 25.6 (21.7) 25.8 (19.9) 19.0(6.7) 25.5 (11.6) 20.8 (16.4) 27.0 (35.1) 27.0 (18.9) 25.0 (19.7) 29.7 (26.2) 14.9 (11.5) 21.3 (13.1) 16.7 (9.4) 17.6(8.9) 19.9 (15.7) SURFACE SUBSTRATE COMPOSITION * 3.8 (0.5) 3.6 (0.7) 3.4 (1.0) 3.9 (0.9) 3.3 (1.0) 3.6 (0.9) 3.9 (0.5) 3.8 (0.5) 3.9 (0.5) 4.3 (0.8) 3.9 (0.7) 4.0 (0.6) 3.3 (0.8) 3.2 (0.5) 2.3 (1.3) 4.6 (0.3) 3.3 (0.9) 3.4(1.0) 2.9 (0.9) 2.5 (1.0) 2.8 (1.3) 3.0 (1.2) 3.1 (0.8) 2.8(1.1) INTERGRAVEL DISSOLVED 02 (mg/1)* 9.6 (0.7) 9.3 (2.5) 11.7(0.4) 10.6 (2.3) 8.7(1.9) 8.7 (2.8) 11.7(0.3) 9.4 (2.3) 9.5 (1.2) 9.5 (1.5) 11.5(0.9) 11.5(0.9) 8.0 (3.0) 9.7 (1.1) 12.2 (0.2) 3.0 1^.1 J 9.3 (1.0) 10.3 (0.8) 11.6(0.6) 9.70 (3.5) 9.3 (0.5) 8.4 (2.6) 8.5 9.8 (2.0) 6.0 (3.5) 6.2 (3.3) 8.1 (2.9) 7.6 (4.6) 5.5 (3.6) 5.5 (4.3) 11.4(0.6) D.D (O.OJ STREAM DISSOLVED 02 (mg/1)* rsi P T - to o> D C M C M D D C M o" ^ ^ C O ^ L O " ^ ' ^ ^ ' © RO O) RO Q t o i s o> D D C M C M D D CVI D 9.9 (0.6) 11.0(0.4) 12.3 (0.2) 12.3(0.4) 9.8 (0.4) 10.6 (0.3) 12.5 11.1 (1.0) 9.9 (0.3) 10.0(1.5) 10.1 (2.9) 12.0(0.5) 9.9 (0.4) 10.0 (1.0) 12.8 (0.4) 10.4(1.6) INTRAGRAVEL TEMPERATURE (C)* 8.4 (0.6) 5.9 (1.1) 0.2 (0.3) 1.8 (1.0) 10.5 (0.9) 8.0 (0.8) 0.0 (0.1) 6.8 (3.3) 8.3 (0.4) 6.2 (0.8) 0.2 (0.2)) 2.1 (1.0) 10.8 (1.3) 8.2 (1.0) U.O (0.1) 6.7 (3.5) 8.7 (0.16) 6.6 (1.8) 0.0 (0.1) I. 9(0.55) II. 6 (1.3) 8.3 (0.8) 0.1 6.0 (4.0) 8.1 (0.6) 6.5 (0.6) 0.4 (0.4) 2.1 (0.9) 10.3 (1.1) 8.2 (0.6) -0.1 (0.1) 5.7 (3.7) STREAM TEMPERATURE (c) 8.3 (0.6) 5.8 (1.0) 0.2 (0.2) 1.9 (1.1) 10.6 (1.0) 7.8 (0.8) N N m m U,U \\J.\JJ 6.7 (3.3) 8.3 (0.5) 6.1 (0.8) 0.1 (0.2) 2.1 (1.1) 10.9 (1.1) 8.2 (1.0) 6.7 (3.5) 8.7 (0.2) 6.6 (1.9) 0.0 (0.1) I. 9 (0.8) II. 5 (1.2) 8.2 (0.9) 6.0 (3.9) 8.3 (0.5) 6.2 (0.6) 0.1 (0.2) 2.3 (1.1) 10.9 (1.2) 8.1 (0.7) -U. I (U, I) 5.8 (3.9) DEPTH (cm) 26.5 (14.9) 13.3 (8.7) 15.8 (10.0) 24.5 (12.2) 20.3 (12.0) 13.3 (9.0) 19.0(12.6) 40.6 (16.3) 17.3 (6.3) 17.0(8.9) 34.0 (12.9) 26.1 (12.9) 19.1 (9.8) 27.7 (14.9) 47.4 (7.6) 40.7 (22.6) 48.4 (11.8) 50.4 (8.8) 35.8 (21.5) 37.7 (16.8) 42.2 (17.8) 39.8 (16.1) 19.0 (18.8) 17.5 (11.9) 27.5 (27.5) 27.6 (16.8) 18.5 (11.0) 25.5(19.6) VELOCITY (m/s) 0.51 (0.28) 0.19(0.18) 0.23 (0.18) 0.28 (0.20) 0.36 (0.24) 0.15 (0.16) 0.28 (0.25) o~ aT ^ C N " ST C O T - T - C M C M T- CM D D O O J R J o oi C M T - m C M r^ . CO tn CO C M ^- CO ^ D D D D D D D 0.32 (0.22) 0.07 (0.05) 0.11 (0.10) 0.16 (0.09) 0.30 (0.12) 0.12 (0.08) 0.14(0.13) 0.13 (0.13) 0.02 (0.04) 0.04 (0.06) 0.12 (0.15) 0.09 (0.08) 0.05 (0.07) 0.08 (0.10) c C O C O ^ C O O - ^ - F O S C O C M ^ T ' T C O ™ " : " N r ^ r N ^ C O S E O M C O C O R N M HABITAT DATE MARGIN JUL-93 SEP-93 DEC-93 APR-94 JUL-94 SEP-94 DEC-94 MEAN THALWAG JUL-93 SEP-93 DEC-93 APR-94 JUL-94 SEP-94 DEC-94 MEAN POOL JUL-93 SEP-93 DEC-93 APR-94 JUL-94 SEP-94 DEC-94 MEAN OFF-CHANNEL JUL-93 SEP-93 DEC-93 APR-94 JUL-94 SEP-94 DEC-94 MEAN o rH £ co ^ .2 •= 2 to w E JO » CO iii CO CO z S 1 « -E 03 Appendix C 2 . Stream and intragravel physical parameters for both broodyears (1993, 1994) combined over a l l locations, s i t e s and seasons for the selected study streams (n=3) of the early Stuart sockeye stock. CREEK VARIABLE GLUSKIE FORFAR KYNOCK p < 0.05 VELOCITY (m/s) Std. Err. Range n 0.27 0.02 0.00-1.45 173 0.26 0.02 0 - 1.23 193 0.29 0.02 0-1.38 174 no DEPTH (cm) Std. Err. Range n 26.4 1.2 3.0-75.0 173 25.7 1.1 1.0-100.0 193 29.3 1.5 2.0-132.0 174 no STREAM TEMP (C) Std. Err. Range n 6.0 0.3 -0.1 - 10.9 171 6.4 0.2 -0.2-10.8 196 6.9 0.3 -13 181 no INTRAGRAVEL TEMPERATURE (C) Std. Err. Range n 6.0 0.26 -0.1 - 10.6 171 6.4 0.24 -0.1 - 11.0 195 6.9 0.29 -0.1 - 12.8 182 no SURFACE SUBSTRATE Std. Err. Range n Duncans 3.7 0.1 1.0-5.2 159 A 3.4 0.1 1.0-5.0 180 B 3.7 0.1 1.0-5.0 156 A *** STREAM DISOLVED OXYGEN (mg/1) Std. Err. Range n Duncans 11.1 0.1 8.2-13.3 171 A 10.9 0.1 7.6-13.1 196 A 10.5 0.1 3.6-12.5 181 B *** INTRAGRAVEL DISOLVED OXYGEN (mg/1) Std. Err. Range n Duncans 9.7 0.2 0.3-12.9 171 A 8.9 0.2 0.3-12.4 195 B 8.8 0.2 0.2-12.1 182 B *** PERMEABILITY (ml/s) Std. Err. Range n 22.7 1.3 3-84 154 24.2 1.5 0-120 171 27.0 1.8 5-129 146 no 1 0 2 

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