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Some effects of temperature on zygote and alevin survival, rate of development and size at hatching and… Murray, Clyde Bruce 1980

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cl SOME EFFECTS OF TEMPERATURE ON ZYGOTE AND ALEVIN SURVIVAL, RATE OF DEVELOPMENT AND SIZE AT HATCHING AND EMERGENCE OF PACIFIC SALMON AND RAINBOW TROUT by CLYDE BRUCE MURRAY B . S c , U n i v e r s i t y of B r i t i s h Columbia, 1973 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) 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. October, 1980 (c) Clyde Bruce Murray, 1980 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 i i ABSTRACT This study provides comparative data on the e f f e c t s of temperature on zygote and a l e v i n s u r v i v a l , r a t e of development to 50 percent hatching and emergence, and a l e v i n and f r y s i z e f o r f i v e species of P a c i f i c salmon (Oncorhynchus) and f o r rainbow t r o u t (Salmo gairdneri). F e r t i l i z e d eggs from each species were incubated i n c o n t r o l l e d temperature baths at f i v e constant temperatures (2°, 5°, 8°, 11° and 14°C). At 2°C, s u r v i v a l f o r coho salmon zygotes was high (85 p e r c e n t ) , moderate f o r sockeye salmon zygotes (40 percent) and low f o r chinook salmon zygotes (4 pe r c e n t ) . No pink and chum salmon or rainbow t r o u t zygotes survived at 2°C. However, at 14°C s u r v i v a l f o r chum salmon and rainbow t r o u t zygotes was high (67 and 85 perc e n t ) , moderate f o r chinook and pink salmon zygotes (50 and 55 percent) and low f o r sockeye salmon zygotes (10 pe r c e n t ) . No coho salmon zygotes survived at 14°C. The same general p a t t e r n f o r temperature and s u r v i v a l holds f o r a l e v i n s . These data suggest that coho and sockeye salmon are adapted to lower i n c u b a t i o n temperatures than the other species. A l l s i x species showed an i n v e r s e r e l a t i o n s h i p between temperature and in c u b a t i o n time to 50 percent hatching and emergence. The data were analysed using l i n e a r r e g r e s s i o n but, even a f t e r a s e r i e s of transformations, the r e l a t i o n s h i p between temperature and development time remained c u r v i l i n e a r . The only exceptions were f o r chum salmon at hatching and pink salmon at emergence. Incubation temperature a l s o i n f l u e n c e s both a l e v i n and f r y s i z e . In general, low i n c u b a t i o n temperatures produce l a r g e r a l e v i n s and f r y than high i n c u b a t i o n temperatures. In a d d i t i o n to data on constant i n c u b a t i o n temperatures, the e f f e c t s of i i i v a r y i n g temperature regimes on the s u r v i v a l , r a t e of development and s i z e of coho salmon and rainbow t r o u t a l e v i n s and f r y were a l s o documented. F e r t i l i z e d eggs from coho salmon and rainbow t r o u t were incubated a t two va r y i n g temperature regimes. The v a r y i n g temperature regimes e i t h e r g r a d u a l l y increased from 5° to 14°C (the s p r i n g regime) or gr a d u a l l y decreased from 14° to 5°C (the f a l l regime). The i n c r e a s i n g temperature regime produces higher s u r v i v a l i n rainbow t r o u t zygotes and a l e v i n s than the decreasing temperature regime. However, i n coho salmon there was no c l e a r d i f f e r e n c e i n zygote and a l e v i n s u r v i v a l w i t h e i t h e r regime. The r a t e of development to hatching f o r zygotes incubated at e i t h e r v a r y i n g temperature regime was s i m i l a r w i t h i n a species because of s i m i l a r mean in c u b a t i o n temperatures between regimes. But, the r a t e of development to emergence f o r a l e v i n s incubated at e i t h e r v a r y i n g temperature regime was d i f f e r e n t because of d i f f e r e n t mean temperatures between regimes. The l i n e a r regressions to hatching and emergence f o r coho salmon and rainbow t r o u t were used to p r e d i c t r a t e s of development f o r zygotes and a l e v i n s incubated w i t h each v a r y i n g temperature regime. The a c t u a l and p r e d i c t e d r a t e s of development to hatching and emergence are s i m i l a r w i t h i n a species. Varying temperature regimes a l s o a f f e c t both a l e v i n and f r y s i z e . The decreasing temperature regime produces l a r g e r a l e v i n s and f r y i n coho salmon and rainbow t r o u t than the i n c r e a s i n g temperature regime. i v TABLE OF CONTENTS Abs t r a c t i i Table of Contents i v L i s t of Tables v i L i s t of Figures i x Acknowledgments x i I n t r o d u c t i o n 1 M a t e r i a l s and Methods 6 Source of Eggs 6 Constant Temperatures Incubation System 7 Sampling During Development 12 P r e s e r v a t i o n 13 Measurements 14 Varying Temperature Regimes Incubation System 14 Data A n a l y s i s 16 R e s u l t s ; 22 Constant Temperatures Regimes 22 Rainbow Trout 22 Temperature and S u r v i v a l 22 Temperature and Development Rate 26 Temperature and S i z e 33 Coho Salmon 37 Temperature and S u r v i v a l 37 Temperature and Development Rate 42 Temperature and S i z e 49 Chinook Salmon 58 Temperature and S u r v i v a l 62 Temperature and Development Rate 62 Temperature and Size 71 Pink Salmon 74 Temperature and S u r v i v a l 74 V Temperature and Development Rate 74 Temperature and Size 80 Sockeye Salmon 86 Temperature and Survival 86 Temperature and Development Rate 86 Temperature and Size 90 Chum Salmon 97 Temperature and Surv i v a l 97 Temperature and Development Rate 101 Temperature and Size . 101 Varying Temperature Regimes 109 Rainbow Trout 109 Temperatury and Surv i v a l I l l Temperature and Development Rate.. I l l Temperature and Size 115 Coho Salmon 118 Temperature and Surv i v a l 118 Temperature and Development Rate 120 Temperature and Size ." 123 Discussion 125 Temperature and Survival 127 Temperature and Development Rates 132 Temperature and Size 144 Varying Temperature Regimes. 146 Summary 148 Li t e r a t u r e Cited 150 v i LIST OF TABLES Table 1. Species names, migration, spawning and emergence times for salmon and trout used i n t h i s study 3 Table 2. Oxygen l e v e l s i n the incubation j a r s . 11 Table 3. The e f f e c t s of preservation (10 percent formalin) on measurements and weights of eggs, alevins and f r y 15 Table 4. Egg number, mean egg diameter, range and mean egg weight for three female rainbow trout 23 Table 5, Days to 50 percent hatching f o r rainbow trout incubated at constant temperatures 29 Table 6. Days to 50 percent emergence for rainbow trout incubated at constant temperatures 32 Table 7. Mean lengths and mean weights of rainbow trout alevins incubated at constant temperatures 36 Table 8. Mean lengths and mean weights of rainbow trout f r y incubated at constant temperatures 38 Table 9. Egg number, mean egg diameter, range and mean egg weight f o r three coho salmon populations 39 Table 10. Days to 50 percent hatching f o r three coho salmon populations incubated at constant temperatures 45 Table 11. The regression equations to 50 percent hatching, c o r r e l a t i o n c o e f f i c i e n t s , and degrees of freedom for three coho salmon populations 48 Table 12. Days to 50 percent emergence for three coho salmon populations incubated at constant temperatures 50 Table 13. The regression equations to 50 percent emergence, c o r r e l a t i o n c o e f f i c i e n t s , and degrees of freedom f o r three coho salmon populations 53 Table 14. Mean lengths and mean weights of coho salmon alevins incubated at constant temperatures 54 Table 15. Mean lengths and mean weights of coho salmon f r y incubated at constant temperatures 59 ) v i i Table 16. Days to 50 percent hatching f o r chinook salmon incubated at constant temperatures 65 Table 17. Days to 50 percent emergence f or chinook salmon incubated at constant temperatures 68 Table 18. Mean lengths and mean weights of chinook salmon alevins incubated at constant temperatures 72 Table 19. Mean lengths and mean weights of chinook salmon f r y incubated at constant temperatures 73 Table 20. Days to 50 percent hatching for pink salmon incubated at constant temperature.s •••• 77 Table 21. Days to 50 percent emergence for pink salmon incubated at constant temperatures 81 Table 22. Mean lengths and mean weights of pink salmon alevins incubated at constant temperatures 84 Table 23. Mean lengths and mean weights of pink salmon f r y incubated at constant temperatures 85 Table 24. Days to 50 percent hatching f o r sockeye salmon incubated at constant temperatures 89 Table 25. Days to 50 percent emergence f o r sockeye salmon incubated at constant temperatures 93 Table 26. Mean lengths and mean weights of sockeye salmon alevins incubated at constant temperatures 96 Table 27. Mean lengths and mean weights of sockeye salmon f r y incubated at constant temperatures 98 Table 28. Days to 50 percent hatching f o r chum salmon incubated at constant temperatures 102 Table 29. Days to 50 percent emergence f o r chum salmon incubated at constant temperatures 105 Table 30. Mean lengths and mean weights of chum salmon alevins incubated at constant temperatures 108 Table 31. Mean lengths and mean weights of chum salmon f r y incubated at constant temperatures 110 Table 32. Percent s u r v i v a l of f e r t i l i z e d eggs to completion of hatching and emergence for rainbow trout incubated at varying temperature regimes 112 v i i i Table 33. Actual and predicted days to 50 percent hatching for rainbow trout incubated at varying temperature regimes 113 Table 34. Actual and predicted days to 50 percent emergence for rainbow trout incubated at varying temperature regimes 114 Table 35. Mean lengths and mean weights of rainbow trout alevins incubated at varying temperature regimes 116 Table 36. Mean lengths and mean weights of rainbow trout f r y incubated at varying temperature regimes 117 Table 37. Percent s u r v i v a l of f e r t i l i z e d eggs to completion of hatching and emergence f or coho salmon incubated at varying temperature regimes 119 Table 38. Actual and predicted days to 50 percent hatching for coho salmon incubated at varying temperature regimes 121 Table 39. Actual and predicted days to 50 percent emergence fo r coho salmon incubated at varying temperature regimes '. 122 Table 40. Mean lengths and mean weights of coho salmon alevins incubated at varying temperature regimes 124 Table 41. Mean lengths and mean weights of coho salmon f r y incubated at varying temperature regimes 126 Table 42. L i t e r a t u r e data and regression equations for the rate of egg' development i n rainbow trout 133 Table 43. L i t e r a t u r e data for the rate of egg development i n coho salmon 136 Table 44. L i t e r a t u r e data for the rate of egg development i n pink salmon 138 Table 45. Rates of development to 50 percent hatching and emergence presented i n t h i s study 140 Table 46. L i t e r a t u r e data for the rate of egg development i n sockeye salmon 141 Table 47. L i t e r a t u r e data f o r the rate of egg development i n chum salmon 143 i x LIST OF FIGURES Figure 1. Mean monthly water temperature for the Seymour River, North Vancouver, B. C 4 Figure 2. The incubation system used for the constant and varying temperature regimes 9 Figure 3. Incubation temperature and percent s u r v i v a l to completion of hatching of f e r t i l i z e d rainbow trout eggs 24 Figure 4. Incubation temperature and percent s u r v i v a l to completion of emergence of f e r t i l i z e d rainbow trout eggs 27 Figure 5. Influence of temperature on 50 percent hatching time i n rainbow trout 30 Figure 6. Influence of temperature on 50 percent emergence time i n rainbow trout 34 Figure 7. Incubation temperature and percent s u r v i v a l to completion of hatching of f e r t i l i z e d eggs i n three coho salmon populations 40 Figure 8. Incubation temperature and percent s u r v i v a l to completion of emergence of f e r t i l i z e d eggs i n three coho salmon populations 43 Figure 9. Influence of temperature on 50 percent hatching time i n three coho salmon populations 46 Figure 10. Influence of temperature on 50 percent emergence time i n three coho salmon populations 51 Figure 11. Influence of temperature on mean a l e v i n length i n three coho salmon populations 56 Figure 12. Influence of temperature on mean f r y length i n three coho salmon populations 60 Figure 13. Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d chinook salmon eggs 63 Figure 14. Influence of temperature on 50 percent hatching time i n chinook salmon 66 X Figure 15. Influence of temperature on 50 percent emergence time i n chinook salmon 69 Figure 16. Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d pink salmon eggs 75 Figure 17. Influence of temperature on 50 percent hatching time i n pink salmon 78 Figure 18. Influence of temperature on 50 percent emergence time i n pink salmon 82 Figure 19. Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d sockeye salmon eggs 87 Figure 20. Influence of temperature on 50 percent hatching time i n sockeye salmon 91 Figure 21. Influence of temperature on 50 percent emergence time i n sockeye salmon 94 Figure 22. Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d chum salmon eggs.«. . • 99 Figure 23. Influence of temperature on 50 percent hatching time i n chum salmon 103 Figure 24. Influence of temperature on 50 percent emergence time i n chum salmon 106 V x i ACKNOWLEDGMENTS This study would not have been possible without the help and cooperation of many i n d i v i d u a l s and organizations. I wish to express my sincere thanks to Dr. J . D. McPhail f or h i s invaluable assistance, advice, and encouragement throughout t h i s study. Thanks also go to Bob Carveth, Marvin Rosenau, Dave Peacock, Ruth Withler, Darlene Belfore, and many others for t h e i r help, comments and encouragement. The help of B. C. Fis h and W i l d l i f e , F i s h e r i e s and Oceans Canada, and the International P a c i f i c Salmon F i s h e r i e s Commission i n supplying salmon and trout eggs i s also greatly appreciated. 1 INTRODUCTION Many aspects of salmonid reproduction ( i . e . redd construction, spawning times, the unusually large eggs, the long i n t e r - g r a v e l incubation period, and the time of f r y emergence) are considered adaptations and, therefore, products of natural s e l e c t i o n (Svardson, 1948; Schaeffer and Elson, 1975). This view i s supported by the growing body of evidence that many reproductive t r a i t s i n P a c i f i c salmon {Oncorhynchus), at l e a s t i n part, are in h e r i t e d (for a review see Ricker, 1972). Although spawning, egg incubation and f r y * emergence are c r i t i c a l phases i n the l i f e cycle of trout and salmon, the r e l a t i o n s h i p s between environ-mental conditions and f r y production are not well understood (Andrew and Geen, 1960). There i s an extensive l i t e r a t u r e on spawning and early l i f e h i s t o r y of salmonids, and i t i s known that environmental factors profoundly influence spawning success, zygote s u r v i v a l , incubation time, f r y s u r v i v a l and f r y s i z e . I t i s , however, s u r p r i s i n g l y d i f f i c u l t to i n t e r p r e t t h i s l i t e r a t u r e . D i f f i c u l t i e s i n i n t e r p r e t a t i o n spring from two main sources: 1) v a r i a b i l i t y i n experimental design and conditions, and 2) differences i n a n a l y t i c a l methods and procedures. These differences combine to make i n t e r s p e c i f i c (and even i n t r a s p e c i f i c ) comparisons almost impossible. The present study investigates the e f f e c t s of temperature on zygote and a l e v i n s u r v i v a l , rate of development and s i z e at hatching and emergence i n f i v e species of P a c i f i c salmon and i n the rainbow trout. The s c i e n t i f i c and common names of the s i x species, t h e i r spawning dates and approximate *Fry are newly emerged, free-swimming young (Allan and R i t t e r , 1977). 2 times of emergence are l i s t e d i n Table 1. A l l f i v e salmon species t y p i c a l l y spawn i n the f a l l or winter. For comparison, the rainbow trout, a spring spawning species, was included i n the study. In c oastal B r i t i s h Columbia the annual water temperature regime follows the pattern outlined i n Figure 1. The actual water temperatures vary from year to year but the general shape of the curve i s consistent. As a r e s u l t of t h i s pattern, f a l l spawning species deposit t h e i r eggs at r e l a t i v e l y high water temperatures, and temperature tends to decline during incubation. In contrast, spring spawning species deposit t h e i r eggs at r e l a t i v e l y low water temperatures, and temperature tends to increase during incubation. If the eggs of spring and f a l l spawners are adapted to these d i f f e r e n t temperature regimes, there should be differences i n the a b i l i t i e s to withstand changes i n temperature. The zygotes of f a l l spawning species should be adapted to r e l a t i v e l y high temperatures early i n development, and be able to withstand d e c l i n i n g temperatures during development. In contrast, the zygotes of spring spawning species should be adapted to low temperatures during early development, and be able to accommodate r i s i n g temperatures during development. The main goal of t h i s study was to provide comparative data for the f i v e B. C. species of P a c i f i c salmon and the rainbow trout on the e f f e c t s of temperature on zygote and a l e v i n s u r v i v a l , rate of development and s i z e at hatching and emergence. S u r p r i s i n g l y , although salmon and trout have been extensively studied almost no comparative data of t h i s type e x i s t . A subsidiary aim was to test the hypothesis that the zygotes of f a l l and spring spawning salmonids are adapted to d i f f e r e n t temperature regimes. The test consisted of s p l i t t i n g egg batches from coho salmon ( f a l l spawners) and rainbow trout (spring spawners) and r a i s i n g the eggs under two tempera-Table 1. Species names, migration, spawning and emergence times for salmon and trout used i n t h i s study (from Scott and Crossman, 1973). S c i e n t i f i c Name Common Name Migration Time Spawning Time Emergence Time Oncorhynchus gorbuscha (Walbaum 1792) Pink salmon Sept.-Oct. Sept .-Oct. April-May Oncorhynchus keta (Walbaum 1792) Chum salmon Sept.-Jan. Oct.- -Jan. April-May pncorhynchus kisutch (Walbaum 1792) Coho salmon Sept.-Mar. Oct.- - A p r i l Mar.-June Oncorhynchus nerka (Walbaum 1792) Sockeye salmon June-Sept. Sept .-Oct. April-May Oncorhynchus tshawytscha (Walbaum 1792) Chinook salmon May-Nov. Sept .-Dec. Mar.-April Salmo gairdneri Richardson 1863 Rainbow or Steelhead trout April-May Nov.-May June-Oct. Jan. -June June-July 4 FIGURE 1 Mean monthly water temperatures f o r the Seymour R i v e r , North Vancouver, B. C. (data from Inland Waters D i r e c t o r a t e 1952-1973). T E M P E R A T U R E °C J L ± J L o i_L J L I I I 6 ture regimes ( f a l l and spring). The f a l l regime started at a high temperature and declined during development; the spring regime started at a low tempera-ture and increased during development. The hypothesis predicts coho eggs w i l l have higher s u r v i v a l under the f a l l regime and lower s u r v i v a l under the spring regime, while rainbow eggs w i l l have higher s u r v i v a l under the spring regime and lower s u r v i v a l under the f a l l regime. MATERIALS AND METHODS Sources of Eggs: A l l eggs were taken from spawning runs and f e r t i l i z e d i n the f i e l d . The eggs were water hardened f o r one hour i n 1.8 L glass j a r s f i l l e d with stream water, and then transported i n a styrofoam ice-chest to the laboratory. T r a n s i t time was always les s than 12 hours. Rainbow trout (S. gairdneri) eggs were c o l l e c t e d from Tunkwa Lake (50°36'N, 120°51'W) on May 25, 1976 and May 30, 1977. In 1976 the eggs were a sample from 10 females and were f e r t i l i z e d at 8.0°C with the m i l t from 10 males. In 1977 the eggs were from a large (563.0 mm), a medium (445.0 mm) and a small (289.0 mm) female. These eggs were kept separate and f e r t i l i z e d with the m i l t from a s i n g l e male (482.0 mm). Coho salmon (O. kisutch) eggs were c o l l e c t e d from three Fraser V a l l e y l o c a l i t i e s : 1) a small stream entering the north end of Chehalis Lake (49°29»N, 122°00'W) on December 29, 1976; 2) E l k Creek (49°10'N, 121°51'W) on A p r i l 6, 1977, and the Salmon River (49°08'N, 122°36'W) on November 11, 1977. The eggs from two females were kept separate i n Chehalis Lake and Salmon River and from one female i n Elk Creek. The eggs from each population 7 were f e r t i l i z e d with the m i l t from a male from that population. The Chehalis eggs were f e r t i l i z e d at 6.0°C, the E l k Creek eggs at 10.0°C and the Salmon River eggs at 9.0°C. Chinook salmon (O. tshawgtscha) eggs were taken from the Babine River (53 21'N, 126U41'W) on September 22, 1976. These eggs were from several females and were f e r t i l i z e d at 14.0°C with the m i l t from several males. Pink salmon (O. gorbuscha) eggs were c o l l e c t e d at the Chilliwack River (49°06'N, 121°29'W) on October 5, 1977. These eggs were from a s i n g l e female and were f e r t i l i z e d at 12.0°C with the m i l t from a s i n g l e male. Sockeye salmon (O. nerka) and chum salmon (O. keta) eggs were taken at Weaver Creek (49°20'N, 121°53*W) on October 25, 1976. The eggs were from a s i n g l e chum and sockeye female and were f e r t i l i z e d at 11.0 C with the m i l t from a s i n g l e chum and sockeye male. Constant Temperatures Incubation System: In the laboratory, eggs were divided into l o t s to be reared at each experimental temperature. .The eggs were drained, t h e i r t o t a l volume measured, and then they were divided into equal l o t s by volume (never l e s s than 150 eggs per l o t ) . The incubation system consisted of three parts: r e f r i g e r a t i o n u n i t s , c o n t r o l l e d temperature baths, and incubation j a r s . The c o n t r o l l e d tempera-ture baths were set for f i v e target temperatures (2.0°, 5.0°, 8.0°, 11.0°, and 14.0°C). The mean temperatures throughout the study were: 2.3 ± 0.97°; 5.1 ± 0.78°; 8.1 ± 0.85°; 11.2 ± 0.98°; and 13.9 ± 0.94°C. F o r t y - l i t r e glass aquaria (50.0 x 27.0 x 30.0 cm) were used f o r each bath. A shelf (25.0 x 27.0 cm i n s i z e and 15.0 cm from the bottom) was placed i n the front 8 h a l f of each bath to support the incubation j a r s ( F i g . 2). The incubation j a r s were 0.7 L wide-mouth glass j a r s (1A.0 x 8.0 cm). Eight centimeters of peagravel was placed i n the bottom of each j a r and a l i f t pipe (1.0 cm diameter) was embedded i n the gravel. Compressed a i r was passed through the l i f t pipe and caused the water to c i r c u l a t e . The compressed a i r also aerated the water. Water flow (5.2 ± 0.2 L/hour) through each j a r was maintained by adjusting the a i r flow through the l i f t pipe. This system ensured that the water around the eggs was saturated with oxygen (Table 2). Several authors (Alderdice et a l . , 1958; Garside, 1959, 1966; S i l v e r et a l . , 1963; Brannon, 1965) have demonstrated that low oxygen l e v e l s retard development. To exclude foreign material and to r e t a i n the a l e v i n s * each ja r was f i t t e d with a screen l i d . Temperature c o n t r o l i n each bath was maintained by heating cold dechlorinated water. The heating unit was a 500 watt heater connected to a s e n s i t i v e thermostat and re l a y . A small platform at the rear of each bath supported the heater, thermostat, and a small i n d i c a t o r l i g h t . The relay was located above each bath. Cold dechlorinated tap water (25.0 L/hour) flowed through a 0.8 cm pipe to the bottom of each bath. The water i n each bath was vigorously aerated to ensure a uniform temperature d i s t r i b u t i o n throughout the bath. During the experiments dechlorinated tap water at U.B.C. varied from 5.0° to 11.0°C. This incoming water was cooled by a r e f r i g e r a t i o n unit (k, horsepower). The r e f r i g e r a t i o n unit cooled water i n a large insulated tank (1.8 x 0.6 x 0.9 m). The water was cooled to 1.0°C and i c e formation *Alevin i s the term used for newly hatched trout or salmon before they emerge from the gravel. 9 FIGURE 2 The i n c u b a t i o n system used f o r the constant and v a r y i n g temperature regimes. 11 Table 2. Oxygen l e v e l s i n the incubation j a r s . Oxygen determined by the Azide method (Horwitz, 1975) and given i n m i l l i -grams per l i t r e . Percent saturation determined from Hutchinson (1957) . Incubation Temperature °C Date 14° 11° 8° 5° 2° Sept. 1977 8.3 9.6 10.5 11.4 12.^ 0 Oct. 9.1 9.8 10.7 11.6 12.0 Nov. 8.2 9.9 10.4 11.6 12.6 Dec. 8.8 9.0 10.0 10.8 12.2 Jan. 1978 8.3 9.0 10.2 10.8 12.9 Feb. 8.3 9.7 10.7 11.5 12.5 Mar. 8.5 9.7 10.8 11.7 12.0 A p r i l 9.2 9.0 10.0 10.8 12.6 May 8.7 8.8 10.0 10.8 12.2 June 9.0 9.3 10.6 11.4 12.0 July 8.8 9.1 10.8 11.6 12.0 Aug. 9.0 9.2 10.9 11.6 12.0 Mean 8.7 9.3 10.5 11.3 12.3 S D 0.35 0.38 0.34 0.30 0 . 3 ; % saturation 86.9 87.5 91.2 91.4 91.4 12 was reduced by v i g o r o u s l y a e r a t i n g the water. A 10.0 m aluminum c o i l was submerged i n the tank and the d e c h l o r i n a t e d tap water was passed through the c o i l . This cooled the tap water to the lowest experimental temperature (2°C). The cooled water then flowed through an i n s u l a t e d 1.3 cm pipe to an adaptor that reduced i t to three 0.8 cm pipes. These pipes supplied water to the 2°, 5° and 8°C temperature baths. The 11° and 14°C temperature baths rece i v e d c o o l water d i r e c t l y from the main d e c h l o r i n a t e d water supply. The only temperature that proved d i f f i c u l t to m a i n t a i n f o r long periods was 2°C. To overcome t h i s problem the 2°C bath was placed d i r e c t l y i n t o the l a r g e i n s u l a t e d tank. This solved the problem and no other d i f f i c u l t i e s were encountered i n ma i n t a i n i n g the d e s i r e d temperatures i n each temperature bath. Water temperatures i n each bath were recorded once a day. The tempera-tures were taken w i t h a standard mercury thermometer c a l i b r a t e d at 0.0° and 100.0°C. Since l i g h t i s known to i n f l u e n c e the development and s u r v i v a l of salmonid eggs and a l e v i n s (Brannon, 1965), a l l temperature baths were held i n shallow water f i l l e d t r a y s and were covered w i t h black p l a s t i c which was removed f o r a maximum of f i v e minutes every day f o r examination and removal of dead eggs. Sampling During Development: A f t e r each egg l o t was placed i n an in c u b a t i o n j a r a sample of 20 eggs was removed. These samples were combined to determine egg s i z e f o r each female. Each day the in c u b a t i o n j a r s were checked and dead eggs removed and stored i n Stockard's s o l u t i o n (5 percent f o r m a l i n + 4 percent g l a c i a l 13 a c e t i c a c i d + 6 percent g l y c e r i n e + 85 percent water). Death was i n d i c a t e d by a pronounced whitening of the egg or embryo. Stockard's s o l u t i o n c l e a r s eggs and once c l e a r e d the eggs were examined under low m a g n i f i c a t i o n . Eggs were c l a s s i f i e d as " f e r t i l i z e d " i f some evidence of c e l l d i v i s i o n was seen. " U n f e r t i l i z e d " eggs showed no s i g n of development. Each week a sample of f i v e eggs was removed from each i n c u b a t i o n j a r and examined under low m a g n i f i c a t i o n to determine the stage of development. Development stages i n salmonids are w e l l documented ( B a t t l e , 1944; P e l l u e t , 1944; Garside, 1959; Knight, 1963; B a l l a r d , 1973). A f t e r e s t a b l i s h i n g the development stage the eggs were returned to the appropriate i n c u b a t i o n j a r . When the eggs hatched the a l e v i n s were removed, counted and placed i n a new i n c u b a t i o n j a r . Since hatching can be p r o t r a c t e d , t h i s was done every day. When 50 percent of the eggs hatched a sample (15-25 a l e v i n s depending on the o r i g i n a l egg number and subsequent s u r v i v a l ) was removed and preserved. Dead a l e v i n s were removed and examined f o r stage of development ( i . e . s t a t e of y o l k a b s o r p t i o n ) . Gross e x t e r n a l d e f o r m i t i e s were a l s o noted. When 50 percent of the a l e v i n s a t t a i n e d n e u t r a l buoyancy and showed a p o s i t i v e r e a c t i o n to l i g h t a sample was removed and preserved. The a c q u i s i t i o n of n e u t r a l buoyancy and a p h o t o p o s i t i v e response are the c r i t e r i a used to d i s t i n g u i s h a l e v i n s from f r y (Bams, 1969; A l l e n and R i t t e r , 1977). P r e s e r v a t i o n : Except f o r the eggs that died during development a l l eggs, a l e v i n s and f r y were preserved i n 10 percent f o r m a l i n . A f t e r three months' storage the samples were washed, weighed, measured, and examined under low m a g n i f i c a t i o n 14 for stage of development before transfer to 37.5 percent isopropol alcohol for permanent storage. Measurements: Samples were measured with Helios Vernier c a l i p e r s . A l l measurements are to the nearest 0.1 mm. Since most of the eggs were not round, the diameter was measured on the longest axis. A l e v i n and f r y length was measured from the t i p of the snout to the end of the hypural pl a t e s . This measurement corresponds to standard length (S.L.) i n adult f i s h . A l l samples were weighed to the nearest 0.01 g on a Sartorius balance. A l l samples were blotted dry before weighing. The e f f e c t s of formalin on measurements and weights were determined by comparing samples before and a f t e r three months' preservation. Formalin preservation caused a 9-14 percent increase i n weight and a 3-5 percent decrease i n length (Table 3). These r e s u l t s are s i m i l a r to those reported by Shetter (1936), Burgner (1962), and Parker (1963). Varying Temperature Regimes Incubation System: Eggs from Tunkwa Lake rainbow trout and the three Fraser River coho salmon populations were used i n these experiments. Instead of the eggs from each female being divided into f i v e l o t s the eggs were divided into seven l o t s . The two extra l o t s were incubated under two varying temperature regimes. The temperature baths and the incubation j a r s were the same as those used i n the constant temperature experiment; however, the two varying temperature regimes were d i f f e r e n t . One bath started at 5.0°C and the 15 Table 3. The e f f e c t s of preservation (10 percent formalin) on measurements and weights of eggs, alevins and f r y . Same material Freshly preserved a f t e r three n material X SD months' X storage SD Change Egg diameter (mm) 100 6.7 0.26 6.4 0.22 4% decrease Egg weight (g) 100 0.14 0.008 0.16 0.007 14% increase A l e v i n length (mm) 100 16.7 0.55 16.2 0.53 3% decrease A l e v i n weight (g) 100 0.11 0.007 0.12 0.011 9% increase Fry length (mm) 100 26.2 0.87 25.0 0.84 5% decrease Fry weight (g) 100 0.24 0.011 0.27 0.011 12% increase 16 temperature was slowly raised during the course of embryonic development to 14.0°C (the spring regime). The other bath started at 14.0°C and was slowly lowered to 5.0°C (the f a l l regime). Once the upper or lower temperature l i m i t s were reached the alevins were maintained at that temperature u n t i l the completion of emergence. The system of temperature adjustment for the varying temperature regimes d i f f e r e d f o r salmon and trout. The development temperatures for coho salmon were adjusted upward or downward by 0.5°C every t h i r d day, while the development temperature for rainbow trout was adjusted by 0.5°C every second day. The d i f f e r e n c e was necessary to ensure that the e n t i r e temperature range was covered up to completion of hatching for each species. Space l i m i t a t i o n s and r e f r i g e r a t i o n c a p a b i l i t i e s made i t necessary to separate the c o n t r o l l e d temperature baths from the varying temperature baths. Another r e f r i g e r a t i o n unit (1/3 horsepower) cooled a smaller insulated tank (0.6 x 0.6 x 0.6 m) containing another submerged 10.0 m aluminum c o i l . Again dechlorinated tap water was passed through the c o i l and cooled f or use i n both varying temperature baths. The two varying temperature baths were held i n a shallow water f i l l e d tray and were covered with black p l a s t i c to exclude l i g h t . A l l the other techniques and procedures outlined f o r the other experi-ments were followed f or each species used i n the varying temperature experiments. Data A n a l y s i s : S u r v i v a l was calculated as the percent of f e r t i l i z e d eggs that survived as eggs or a l e v i n s . U n f e r t i l i z e d eggs were not used i n the c a l c u l a t i o n . I t 17 was assumed that the sample of alevins removed at 50 percent hatching would have suffered the same rate of s u r v i v a l as the remaining a l e v i n s . A p l o t of cumulative hatching or emergence against time gives a c l a s s i c a l sigmoid curve with the time from about 25 to 75 percent hatching or emergence approximating a s t r a i g h t l i n e to which a regression l i n e can be f i t t e d by l e a s t squares. The 50 percent hatching and emergence time's were calculated using t h i s method (Colby and Brooke, 1969) . The data for development time (50 percent hatching or emergence and development temperature) were analysed using a within-block si n g l e regression program ( G i l b e r t , 1967). The program works out a fresh analysis for each p a i r of X and Y vari a t e s and for transformations of the variates ( i . e . l n X, Y; l n X, l n Y; X, l n Y). For each Y-variate, the program p r i n t s an i n i t i a l analysis of variance and a B a r t l e t t ' s test of homogeneity of variances within blocks. This i s followed by a within-block regression on every X (Y = A + BX). The program p r i n t s regression c o e f f i c i e n t s A and B (with standard e r r o r s ) , c o r r e l a t i o n between Y and X, and analysis of variance of Y (in c l u d i n g homogeneity of regression slope and intercept between blocks, and a test for curvature by adding X 2 to the regression equation). The regression equation with the highest c o r r e l a t i o n c o e f f i c i e n t and the l e a s t curvature was used to describe the data. Whenever possible l i t e r a t u r e data on the rate of development were c o l l e c t e d and analysed f o r each species. However, there are cer t a i n assump-tions that were made. A l l the l i t e r a t u r e data were assumed to be reported as 50 percent hatching or emergence times and mean development temperatures unless otherwise stated. When l i t e r a t u r e data were reported as degree-days and i f e i t h e r the time to development ( i n days) or the mean temperature of 18 development was also given the other component was calculated from the degree-days. In most cases the l i t e r a t u r e data were incomplete and the analysis was only performed i n order to compare the r e s u l t s f o r each species i n the present study with the l i t e r a t u r e data i n the most general terms. Studies on the e f f e c t s of temperature on the rate of development have been considered and reviewed extensively. Thorough discussions of f h i s l i t e r a t u r e have been presented by Hayes (1949), Hayes et a l . (1953), Kinne and Kinne (1962), Blaxter (1969), and B o t t r e l l (1975). A review i s presented here only i n an e f f o r t to c l a r i f y and explain some of the d i f f i c u l t i e s i n making comparisons and the need for standardized data reporting. It i s t r a d i t i o n a l i n hatchery p r a c t i c e to use the t o t a l number of "thermal u n i t s " or degree-days to indi c a t e developmental progress (Wallich, 1901; Wales, 1941). One degree-day i s defined as the number of degrees above 0 ° c or 32°F per day. These degree units per day are cumulative and give an estimate of the rate of development i n degree-days. Confusion a r i s e s when the system used (Fahrenheit or Centigrade) i s not c l e a r l y defined. Degree-days were o r i g i n a l l y thought to be constant ( i . e . TD = k, where T i s temperature and D i s days). This i s only true over a rather narrow range of s u i t a b l e temperatures, and the a p p l i c a t i o n of degree-days for a wide range of temperatures represents only a rough r e l a t i o n (Braum, 1978). In f a c t , the sum of the temperature units i s not constant but increases r e g u l a r l y with increasing temperature. Also the number of degree-days to a given stage of development i s not constant for d i f f e r e n t temperature regimes (Peterson et a l . , 1977). This makes comparison between f a c i l i t i e s and species d i f f i c u l t i f not impossible. 19 Another r e l a t i o n s h i p used to describe r a t e of development i s the r e c i p r o c a l transform (1/D). This r e l a t i o n s h i p assumes that the r a t e of development i s l i n e a r l y r e l a t e d to temperature (1/D = a + bT, where a i s the i n t e r c e p t and b i s the s l o p e ) . In f a c t when such r e c i p r o c a l r a t e s are p l o t t e d over a wide temperature range the r e s u l t i n g curve i s an elongate sigmoid. Several i n v e s t i g a t o r s , i n c l u d i n g Johansen and Krogh (1914), Hayes (1949), Seymour (1956) and Garside (1959) tend to ignore the i n f l e c t i o n s of such a curve and consider only the c e n t r a l , l i n e a r segment and e x t r a p o l a t e l i n e a r l y to the X i n t e r c e p t to determine the temperature of development or p h y s i o l o g i c a l zero (Garside, 1966). P h y s i o l o g i c a l zero c a l c u l a t e d i n t h i s manner u s u a l l y r e s u l t s i n an extr a p o l a t e d X - i n t e r c e p t below zero, a t h e o r e t i -c a l p o i n t , s i n c e the l e t h a l temperature f o r development i n salmonids i s somewhat higher. In a d d i t i o n , a b n o r m a l i t i e s may occur at l e s s extreme temperatures which are not n e c e s s a r i l y l e t h a l i n the s t r i c t sense but are i n a f u n c t i o n a l sense. B o t t r e l l (1975) a l s o p o i n t s out that the r e c i p r o c a l transformation w i l l not give the homogeneity of v a r i a n c e , normality and a d d i t i v i t y r e q u i r e d f o r r e g r e s s i o n a n a l y s i s unless these already e x i s t i n the raw data. These l i m i t a t i o n s make the r e c i p r o c a l transformation i n a p p r o p r i a t e f o r comparison of r a t e s of development f o r s e v e r a l species over a wide range of temperature. Both B l a x t e r (1969) and B o t t r e l l (1975) conclude that i n order to meet the assumptions necessary f o r r e g r e s s i o n a n a l y s i s (homogeneity of v a r i a n c e , n o r m a l i t y and a d d i t i v i t y ) i t i s more appropriate to r e l a t e the log a r i t h m of development time to temperature ( i . e . l n D = a + bT). This i s e s s e n t i a l l y the Van't Hoff or Arrhenius equation ( Q - ^ Q ) that when temperature i s increased i n an a l g e b r a i c p r o g r e s s i o n , the r e a c t i o n v e l o c i t y increases i n a geometric progression. 20 Embody (1934) was the f i r s t to use Van't Hoff's law to describe the r e l a t i o n s h i p between temperature and r a t e of development i n salmonids. The r e s u l t s were obtained from experimental i n c u b a t i o n i n s e v e r a l d i f f e r e n t h a t c h e r i e s f o r rainbow, brown, brook and lake t r o u t so that a wide tempera-ture range f o r each species was a v a i l a b l e f o r a n a l y s i s . Embody found that the r e l a t i o n s h i p of the logarithm of development time to mean hatching i n days and mean temperature of development f o r brown t r o u t and l a k e t r o u t were s t r a i g h t l i n e s throughout the temperature range a v a i l a b l e f o r comparison. Therefore, they conformed s t r i c t l y to Van't Hoff's law. But the r e l a t i o n s h i p f o r brook t r o u t was c u r v i l i n e a r w i t h the r a t e of development decreasing above 10°C and i n c r e a s i n g below 3°C. The r e l a t i o n s h i p f o r rainbow t r o u t was a l s o c u r v i l i n e a r and between 9° and 10°C the r a t e of development decreased. B o t t r e l l (1975) analysed the l o g a r i t h m r e l a t i o n s h i p s between temperature and d u r a t i o n of egg development i n nine species of Cladocera and Copepoda and found t h a t a s i g n i f i c a n t c u r v i l i n e a r r e l a t i o n s h i p e x i s t e d f o r a l l nine species. A n a l y s i s using a quadratic of the form: l n D = l n a + b l n T + c ( l n T ) 2 gave an improved f i t f o r ei g h t of the species but f a i l e d to remove the c u r v i l i n e a r i t y . Further a n a l y s i s of r e s u l t s from the l i t e r a t u r e on seventeen species of Cladocera and Copepoda r e s u l t e d i n s i g n i f i c a n t c u r v i -l i n e a r r e l a t i o n s h i p s i n f i f t e e n of the species. When the logarithms of development time i n days to 50 percent hatching and 50 percent emergence are p l o t t e d a gainst temperature i n the present study a c u r v i l i n e a r p a t t e r n i s present f o r a l l seven species. These r e s u l t s along w i t h the r e s u l t s of Embody (1934), Garside (1966) and Peterson et a l . (1977) i n d i c a t e that c u r v i l i n e a r i t y i s a general phenomenon f o r salmonids and that f u r t h e r curve f i t t i n g of the data i n the present study may increase the p r e d i c t i v e value of 21 the model but w i l l not n e c e s s a r i l y e l i m i n a t e c u r v i l i n e a r i t y . The semilogar-i t h m i c model used i n t h i s study has an advantage over a quadratic model because i t i s the most e a s i l y i n t e r p r e t e d s i n c e i t has only one term d e f i n i n g the slope r a t h e r than s e v e r a l terms. I f e e l that the r e g r e s s i o n equations presented i n t h i s study give p r e d i c t i o n s , which although not p e r f e c t , are s u i t a b l e f o r comparison u n t i l f u r t h e r experimental data are a v a i l a b l e . To examine the s i g n i f i c a n c e of d i f f e r e n c e s i n l e n g t h at hatch or emergence between the v a r i o u s constant i n c u b a t i o n temperatures f o r each female or s p e c i e s , the observations were analysed using GENLIN (Greig and B j e r r i n g , 1977). GENLIN i s a program that performs t e s t s i n an unbalanced, f i x e d - e f f e c t a n a l y s i s of v a r i a n c e . The program p r i n t s a l l frequencies, means, standard d e v i a t i o n s , p r e d i c t e d means, and standard e r r o r s of p r e d i c t e d means. I t a l s o t e s t s f o r homogeneity of v a r i a n c e . The p r e d i c t e d means were test e d w i t h a m u l t i p l e range t e s t (Duncan's run t e s t ) . Comparisons i n v o l v i n g s e v e r a l females or populations of one species were a l s o analysed using GENLIN. A p a i r e d t - t e s t was used to analyse the e f f e c t of the v a r y i n g temperature regimes on l e n g t h at hatch or emergence (TRIP, Le and T e n i s c i , 1977). A l l t e s t s of s i g n i f i c a n c e use the 0.05 l e v e l of p r o b a b i l i t y (Sokal and R o h l f , 1969; G i l b e r t , 1973). 22 RESULTS CONSTANTS TEMPERATURE REGIMES RAINBOW TROUT: In 1976 the rainbow t r o u t eggs from Tunkwa Lake were a mix from s e v e r a l females. Egg diameter ranged from 3.4 to 5.8 mm (mean = 4.9 mm, SD = 0.54 mm, n = 100). The mean weight of preserved, f e r t i l i z e d eggs was 0.09 g (SD = 0.025 g). In 1977 the eggs from Tunkwa Lake were obtained from a l a r g e , a medium, and a sm a l l s i z e d female t r o u t . Table 4 gives egg number, mean egg diameter, and mean egg weight f o r each female. A n a l y s i s of variance suggests a d i f f e r e n c e i n mean egg diameter between females (F c a l = 206.3; F tab (3,146; 0.05) = 2.3), and Duncan's run t e s t confirms that the s m a l l , medium and l a r g e females produced d i f f e r e n t s i z e d eggs. Apparently a l l the 1976 eggs from Tunkwa Lake were f e r t i l e , and those that died during i n c u b a t i o n a l l showed evidence of embryonic development. In 1977 approx-imately h a l f the eggs from each female survived t r a n s p o r t to the l a b o r a t o r y . Only eggs that survived t r a n s p o r t were used i n the experiment. Temperature and S u r v i v a l : Figure 3 shows s u r v i v a l of f e r t i l i z e d eggs to completion of hatching i n both years (1976 and 1977). For temperatures from 5° to 14°C zygote s u r v i v a l was about 60 to 70 percent i n 1976; however, i n the 1977 data there are i n d i c a t i o n s that over the same temperature range (5° to 14°C) d i f f e r e n -t i a l s u r v i v a l i s ass o c i a t e d w i t h egg s i z e . S u r v i v a l of small eggs was high (95-100 percent) at these temperatures; but s u r v i v a l of l a r g e eggs was complete a t 5°C, 85 percent at 11°C and near 95 percent at 14°C. Medium 23 Table 4. Egg number, mean egg diameter, range and mean egg weight f o r three female rainbow t r o u t (Tunkwa Lake, 1977). Female S.L. Egg Egg diameter Range Egg weight (mm) number (mm) (mm) (g) n x SD x SD Large 563.0 2560 50 5.7 0.24 4.8-6.2 0.09 0.007 Medium 445.0 1370 50 4.8 0.18 4.5-5.2 0.07 0.009 Small 289.0 1476 50 4.4 0.2 3.9-5.1 0.06 0.007 24 FIGURE 3 Incubation temperature and percent s u r v i v a l to completion of hatching of f e r t i l i z e d rainbow t r o u t eggs (Tunkwa Lake). 25 R A I N B O W T R O U T 1976 L A R G E F E M A L E R A I N B O W T R O U T 1977 M E D I U M F E M A L E R A I N B O W T R O U T 1977 S M A L L F E M A L E R A I N B O W T R O U T 1977 2 4 6 8 10 12 14 T E M P E R A T U R E °C 26 s i z e d eggs survived w e l l a t 5°C (98 percent) but s u r v i v a l decreased to 78 percent at 11°C, and then increased to 90 percent at 14°C. In both years, at 2°C, zygote s u r v i v a l was zero. At temperatures between 11° and 14°C the zygotes died at a l l stages i n development. At other temperatures, i n both years, death tended to occur at s p e c i f i c development stages. At 5° and 8°C death occurred j u s t before and during hatching. At 2°C the zygotes died during b l a s t o d i s c c l o s u r e . Figure 4 shows s u r v i v a l of f e r t i l i z e d eggs to the completion of f r y emergence. Most of the a l e v i n m o r t a l i t y occurred s h o r t l y a f t e r hatching. In 1976 the only a l e v i n deaths were at 14°C, but i n 1977 a l l the a l e v i n s that hatched at 14°C, and a l l the a l e v i n s from the medium s i z e d female that hatched at 5°C, died immediately a f t e r hatching. Temperature and Development Rate: Development times f o r Tunkwa Lake rainbow t r o u t incubated at each of the constant temperatures are presented i n Table 5. A n a l y s i s of v a r i a n c e i n d i c a t e s no s i g n i f i c a n t d i f f e r e n c e among females or between years (F c a l = 0.1, F tab (3, 13; 0.05) = 3.4). Regression a n a l y s i s i n d i c a t e s an i n v e r s e r e l a t i o n s h i p between development r a t e and temperature (F c a l = 5875.1, F tab (1, 8; 0.05) = 5.3). The o v e r a l l r e g r e s s i o n of development time on temperature ( F i g . 5) i s described by the equation l n D = 4.860 - 0.143 T (D = development time i n days and T = temperature i n degrees C). The c o r r e l a t i o n c o e f f i c i e n t i s -0.994 and a t e s t f o r curvature i s s i g n i f i c a n t (F c a l = 48.4, F tab (1, 8; 0.05) = 5.3). The time required f o r 50 percent of the rainbow t r o u t to emerge at each constant temperature i s presented i n Table 6. The r e s u l t s among females and 27 FIGURE 4 Incubation temperature and percent s u r v i v a l to completion of emergence of f e r t i l i z e d rainbow t r o u t eggs (Tunkwa Lake). \ 28 0 R A I N B O W T R O U T 1976 • L A R G E F E M A L E R A I N B O W T R O U T 1977 A M E D I U M F E M A L E R A I N B O W T R O U T 1977 • S M A L L F E M A L E R A I N B O W T R O U T 1977 29 Table 5. Days to 50 percent hatching for rainbow trout (Tunkwa Lake) incubated at constant temperatures (L = 563.0 mm °-; M = 445.0 mm °-; S = 289.0 mm °-) . Target Incubation Days to temperature temperature ' Female 50 percent (°C) Year (°C) s i z e hatching In days x SD 14.0 1976 13.8 0.25 18.0 2.89 1977 13.8 0.67 L 18.8 2.93 M 18.8 2.93 S 18.5 2.92 11.0 1976 11.0 0.66 24.4 3.20 1977 11.0 0.23 L 26.5 3.24 M 24.6 3.20 S 25.3 3.23 8.0 1976 7.9 0.54 38.3 3.65 1977 8.1 0.62 L 40.0 3.69 M 39.8 3.69 S 39.8 3.69 5.0 1976 5.2 0.64 59.2 4.08 1977 5.1 0.78 L , M 60.4 4.10 S 61.4 4.12 2.0 1976 2.3 0.83 107.0 4.67 1977 2.1 0.87 L 109.8 4.70 M 30 FIGURE 5 Influence of temperature on 50 percent hatching time i n rainbow t r o u t (Tunkwa Lake). 31 32 Table 6. Days to 50 percent emergence f o r rainbow t r o u t (Tunkwa Lake) incubated at constant temperatures (L = 563.0 mm M = 445.0 mm S - 289.0 mm $ ) . Target Incubation Days to temperature temperature Female 50 percent (°C) Year ( C) s i z e emergence l n days SD 14.0 11.0 8.0 5.0 2.0 1976 1977 1976 1977 1976 1977 1976 1977 1976 1977 13.8 13.8 11.0 11.0 7.9 8.1 5.2 5.1 2.3 2.1 0.22 0.63 0.64 0.27 0.59 0.67 0.68 0.73 0.81 0.83 32.2 3.47 L M S L M S L M S L M S L M 41.5 41.7 41.2 41.9 63.9 65.6 65.3 65.8 102.3 104.5 3.73 3.73 3.72 3.74 4.15 4.18 4.18 4.18 4.63 4.65 33 between years are so s i m i l a r that they were combined f o r the r e g r e s s i o n a n a l y s i s . Regression a n a l y s i s suggests an in v e r s e r e l a t i o n s h i p between 50 percent emergence time and temperature (F c a l = 1724.6, F tab (1, 8; 0.05) = 5.3). The r e g r e s s i o n of 50 percent emergence time on temperature ( F i g . 6) i s described by the equation l n E = 5.292 - 0.140 T (where E = time i n days to 50 percent emergence and T = temperature i n degrees C). "The c o r r e l a t i o n c o e f f i c i e n t i s -0.991 and there i s s i g n i f i c a n t curvature (F c a l = 24.6, F tab (1, 8; 0.05) = 5.3). Temperature and S i z e : The mean lengths and weights of rainbow t r o u t a l e v i n s incubated at each temperature are presented i n Table 7. A n a l y s i s of variance i n d i c a t e s that i n c u b a t i o n temperature has no e f f e c t on the mean lengths of a l e v i n s produced i n 1976 or on a l e v i n s from small eggs i n 1977 (1976 F r a t i o = 2.30, DF = 3,56, p = 0.09; small F r a t i o = 0.87, DF = 3,56, p >0.05). Incubation temperature, however, has a s i g n i f i c a n t e f f e c t on the mean length of a l e v i n s produced by medium and'large eggs i n 1977 (medium F r a t i o = 11.89, DF = 3,56, p <0.05; l a r g e F r a t i o = 5.45, DF = 2,69, p <0.05). When mean a l e v i n lengths are compared f o r d i f f e r e n t temperatures (Ducan's run t e s t ) there are two homogeneous subsets f o r both medium and l a r g e eggs (a 11°C subset; and a 14°, 8° and 5°C subset). At both egg s i z e s the longest a l e v i n s are produced at 5°C and the s h o r t e s t at 11°C. Table 7 i n d i c a t e s that a l e v i n weight shows the same p a t t e r n of change as l e n g t h w i t h temperature. A l e v i n s incubated at 11°C are l i g h t e r than those incuba ted at 5 , 8 and 14"C. The data i n Table 7 suggest both a l e v i n l ength and weight are p a r t i a l l y determined by egg s i z e . 34 FIGURE 6 Influence of temperature on 50 percent emergence time i n rainbow t r o u t (Tunkwa Lake). 35 ~ 5.0 - . 36 Table 7. Mean lengths and mean weights of rainbow t r o u t a l e v i n s (Tunkwa Lake) incubated at constant temperatures (L = 563.0 mm °-; M = 445.0 mm °-; S = 289.0 mm ? ) . Target i , „ „ , 1 o Length (mm) Weight (g) temperature Female (°C) Year s i z e n x SD x SD 14.0 1976 15 12.58 1.653 0.08 ' 0.015 1977 L 15 12.90 0.611 0.08 0.009 M 15 12.23 0.634 0.06 0.007 S 15 11.77 0.467 0.05 0.009 11.0 1976 15 12.41 1.357 0.07 0.017 1977 L 15 12.16 1.024 0.08 0.010 M 15 11.10 0.770 0.05 0.008 S 15 11.67 0.424 0.04 0.010 8.0 1976 15 13.11 0.872 0.08 0.019 1977 L 15 12.60 0.635 0.08 0.010 M 15 11.96 0.413 0.05 0.009 S 15 11.56 0.714 0.04 0.011 5.0 1976 15 11.85 1.621 0.08 0.018 1977 L M 15 11.91 0.636 0.06 0.008 S 15 11.83 0.673 0.05 0.008 2.0 1976 37 Table 8 presents mean lengths and weights of rainbow t r o u t f r y incubated at each constant temperature. A n a l y s i s of variance i n d i c a t e s no e f f e c t o f i n c u b a t i o n temperature on mean f r y l e n g t h i n 1976 (F r a t i o = 2.68, DF = 3,56, p >0.05). In 1977 a l l a l e v i n s died before emergence at 14°C, and at 5°C a l l 7 the a l e v i n s from medium and l a r g e eggs d i e d . This m o r t a l i t y makes compari-sons among females d i f f i c u l t ; however, i t i s c l e a r from Table 8 that f r y le n g t h and weight are at l e a s t p a r t i a l l y determined by egg s i z e . COHO SALMON: Coho salmon eggs were c o l l e c t e d from three po p u l a t i o n s : a winter spawning p o p u l a t i o n , Chehalis Lake; a s p r i n g spawning p o p u l a t i o n , E l k Creek; and a f a l l spawning p o p u l a t i o n , Salmon R i v e r . Table 9 gives egg number, mean egg diameter and mean egg weight f o r each female and each p o p u l a t i o n . A n a l y s i s of variance i n d i c a t e s a s i g n i f i c a n t d i f f e r e n c e i n mean egg diameter f o r each female (F c a l = 528.6, F tab (4, 495; 0.05) = 2.4). F e r t i l i z a t i o n was s u c c e s s f u l f o r eggs from a l l three coho pop u l a t i o n s , and u n f e r t i l i z e d eggs accounted f o r l e s s than one percent of the t o t a l number of eggs from each female. Temperature and S u r v i v a l : Figure 7 shows s u r v i v a l to completion of hatching f o r eggs from each female. For Chehalis Lake and Salmon R i v e r coho eggs s u r v i v a l during development and hatching was high (76-99 percent) at temperatures of from 2° to 11°C; however, at 14°C s u r v i v a l was low (0-14 percent) i n both pop u l a t i o n s . E l k Creek coho zygotes a l s o had high s u r v i v a l (75 percent) a t 5°, 8°, and 11°C and low s u r v i v a l (10 percent) at 14°C, but u n l i k e the other 38 Table 8. Mean lengths and mean weights of rainbow trout f r y (Tunkwa Lake) incubated at constant temperatures (L = 563.0 mm ¥; M = 445.0 mm S = 289.0 mm ¥) . temperature Female L e n g t h ( m m ) W e i S h t <«> (°c) Year s i z e n X SD X SD 14.0 1976 1977 L M 15 20.36 1.224 0.13 0.017 11.0 1976 S 15 19.94 1.672 0.11 0.019 1977 L M S 15 15 15 19.57 1835 16.96 0.732 0.711 0.515 0.12 0.10 0.07 0.015 0.019 0.012 8.0 1976 15 20.96 0.990 0.14 0.018 1977 L M S 15 15 15 20.50 18.54 17.56 0.723 0.924 0.823 0.13 0.11 0.07 0.017 0.016 0.014 5.0 1976 1977 L 15 20.60 1.288 0.14 0.020 M S 15 17.98 0.295 0.09 0.019 39 Table 9. Egg number, mean egg diameter, range and mean egg weight f o r three coho salmon pop u l a t i o n s . Egg Egg diameter Range Egg weight L o c a t i o n Female number C ™ 1 ) (mm) (g) n x SD x SD Chehalis 1 1210 100 7.5 0.29 7.0-7.9 0.24 0.016 L a k e 2 2274 100 6.9 0.22 6.5-7.4 0.23 0.015 E l k Creek 1 1152 100 6.6 0.22 6.2-7.2 0.17 0.013 Salmon 1 1314 100 7.7 0.28 7.1-7.1 0.25 0.014 Riv e r 2 1412 100 7.8 0.23 7.2-8.4 0.26 0.017 40 FIGURE 7 Incubation temperature and percent s u r v i v a l to completion of hatching of f e r t i l i z e d eggs i n three coho salmon populations (Chehalis Lake, E l k Creek and Salmon R i v e r ) . f 41 • C H E H A L I S L A K E F E M A L E 1 • C H E H A L I S L A K E F E M A L E 2 • E L K C R E E K F E M A L E 1 A S A L M O N R I V E R F E M A L E 1 A S A L M O N R I V E R F E M A L E 2 42 populations E l k Creek zygotes a l s o showed low s u r v i v a l (33 percent) at 2 UC. At low temperatures (2° and 5°C) death occurred i n a l l three populations at blastopore c l o s u r e . At higher temperatures (8°, 11°, and 14°C) death occurred during hatching. Figure 8 shows a l e v i n s u r v i v a l to completion of emergence f o r eggs from each female and each p o p u l a t i o n . Few a l e v i n s survived (0-5 percent) at 14°C, but at other temperatures a l e v i n s u r v i v a l was high i n a l l populations. The a l e v i n s died j u s t a f t e r hatching. Temperature and Development Rate: Time re q u i r e d f o r development to hatching f o r each coho pop u l a t i o n at each constant temperature i s presented i n Table 10. The r e s u l t s f o r females w i t h i n a p o p u l a t i o n are s i m i l a r , and a n a l y s i s of variance i n d i c a t e s no s i g n i f i c a n t d i f f e r e n c e between females w i t h i n a population (Chehalis F c a l = 0.0, F tab (1, 8; 0.05) = 5.3; Salmon F c a l = 0.0, F tab (1, 6; 0.05) = 6.0). Therefore, the r e s u l t s f o r females w i t h i n populations were pooled. Regression a n a l y s i s suggests an i n v e r s e r e l a t i o n s h i p between hatching time and temperature (F c a l = 3459.1; F tab (1, 16; 0.05) = 4.5). However, the i n d i v i d u a l b l o c k regressions are not homogeneous (the slopes are d i f f e r -ent, F c a l = 12.6; F tab (2, 16; 0.05) = 3.6) and there i s s i g n i f i c a n t curvature present (F c a l = 60.9; F tab (1, 16; 0.05) = 4.5). A comparison of slopes using a Duncan's run t e s t suggest that there are three homogeneous subsets, one f o r each p o p u l a t i o n . The i n d i v i d u a l regressions are shown i n Figure 9, and the r e g r e s s i o n equations and c o r r e l a t i o n c o e f f i c i e n t s are presented i n Table 11. The times r e q u i r e d f o r development to emergence f o r each coho pop u l a t i o n 43 FIGURE 8 Incubation temperature and percent s u r v i v a l to completion of emergence of f e r t i l i z e d eggs i n three coho salmon populations (Chehalis Lake, E l k Creek and Salmon R i v e r ) . kk a C H E H A L I S L A K E F E M A L E 1 • C H E H A L I S L A K E F E M A L E 2 • E L K C R E E K F E M A L E 1 A S A L M O N R I V E R F E M A L E 1 A S A L M O N R I V E R F E M A L E 2 45 Table 10. Days to 50 percent hatching f o r three coho salmon populations incubated at constant temperatures. Target temperature (°C) Incubation temperature (°C) x SD Days to 50 percent hatching Female 1 2 l n Days to 50 percent hatching Female 1 2 14.0 Chehalis Lake 13. 8 1 .35 31 .0 31. 1 3 .43 3 .44 Elk Creek 13. 9 0 .64 36 .0 — 3 .58 — Salmon R i v e r 13. 8 0 .98 — — — — — 11.0 Chehalis Lake 10. 9 0, .47 43 .2 42. 1 3 .77 3, .74 E l k Creek 11. 0 0, .20 42, .3 — 3, .74 — Salmon R i v e r 10. 9 0. .98 38, .8 37. 7 3, .66 3, .62 8.0 Chehalis Lake 7. 9 0. .30 62. .7 61. 2 4, .14 4. .11 E l k Creek 8. 1 0. .30 63. .2 — 4, .15 — — Salmon R i v e r 8. 0 0. .13 . 55. .8 52. 1 4. .02 3. .95 5.0 Chehalis Lake 5. 0 ' 0. .20 90. ,5 89. 4 4. ,51 4. ,49 Elk Creek 5. 1 0. ,57 88. ,2 - 4. ,48 — Salmon R i v e r 5. 1 0. ,68 87. ,5 86. 8 4. ,47 4. ,46 2.0 Chehalis Lake 2. 3 0. 95 165. 0 167. 0 5. 11 5. 12 E l k Creek 2. 1 0. 64 159. 0 - 5. 07 — — Salmon R i v e r 2. 1 0. 57 158. 7 159. 0 5. 07 5. 07 46 FIGURE 9 I n f l u e n c e of temperature on 50 percent hatching time i n three coho salmon populations (Chehalis Lake, E l k Creek and Salmon R i v e r ) . 47 6 .0 - i CO cu c 5.0-O Z X o r -< X 4.0-O LU 1-3.0-• C H E H A L I S L A K E • E L K C R E E K A S A L M O N R I V E R T 2 I 4 6 T 8 T E M P E R A T U R E I 10 c» i i i 12 14 48 Table 11. The r e g r e s s i o n equations to 50 percent hatching, c o r r e l a t i o n c o e f f i c i e n t s , and degrees of freedom f o r three coho salmon populations. Regression equation to C o r r e l a t i o n Degrees of L o c a t i o n 50 percent hatching c o e f f i c i e n t freedom Chehalis Lake l n D 5.273 - 0.137 T r - 0.991 E l k Creek l n D 5.194 - 0.124 T r - 0.983 Salmon R i v e r l n D 5.325 - 0.159 T r - 0.993 49 at each temperature are presented i n Table 12. The r e s u l t s f o r females w i t h i n populations are s i m i l a r , and a n a l y s i s of vari a n c e i n d i c a t e s no s i g n i f i c a n t d i f f e r e n c e s between females w i t h i n populations (Chehalis F c a l = 0.0, F tab (1, 8; 0.05) = 5.3; Salmon F c a l = 0.0, F tab (1, 6; 0.05) = 6.0) Again, r e s u l t s were combined f o r each p o p u l a t i o n . A n a l y s i s of variance i n d i c a t e s an inverse r e l a t i o n s h i p between emergenc time and temperature (F c a l = 861.6, F tab (1, 11; 0.05) = 4.8). The i n d i v i d u a l r e g r e s s i o n s are not homogeneous (the slopes are d i f f e r e n t , F c a l = 5.8, F tab (4, 11; 0.05) = 3.4) and there i s s i g n i f i c a n t curvature present (F c a l = 6.0, F tab (1, 11;\0.05) = 4.8). A Duncan's run t e s t comparing the slopes i n d i c a t e s that there are three homogeneous subsets (Chehalis Lake, Salmon R i v e r , and E l k Creek). The i n d i v i d u a l r e g r e s s i o n l i n e s are shown i n Figure 10 and the r e g r e s s i o n equations aand c o r r e l a t i o n c o e f f i c i e n t s are presented i n Table 13. The slopes of the emergence and hatching r e g r e s s i o n l i n e s f o r Chehalis Lake (F c a l = 21.0, F tab (1, 15; 0.05) - 4.5), Salmon R i v e r (F c a l - 13.1, F tab (1, 11; 0.05) = 4.8) and E l k Creek (F c a l = 8.4, F tab (1, 4; 0.05) = 7.7) are not the same. For Chehalis Lake and Salmon River coho the r a t e of development (as i n d i c a t e d by the slope) decreased a f t e r hatching, w h i l e f o r E l k Creek the r a t e of development increased. Temperature and S i z e : The mean lengths and weights of coho a l e v i n s incubated at constant temperatures are presented i n Table 14. A n a l y s i s of variance i n d i c a t e s that females s i g n i f i c a n t l y a f f e c t the mean len g t h of a l e v i n s at hatching (F r a t i o = 125.1, DF = 4,300, p <0.05). A comparison of o v e r a l l mean lengths 50 Table 12. Days to 50 percent emergence f o r three coho salmon populations incubated at constant temperatures. Target temperature (°C) Incubation temperature (°C) SD Days to 50 percent emergence Female 1 2-l n Days to 50 percent emergence Female 1 2 14.0 Chehalis Lake 13. 9 1. .01 63. .2 62. .8 4. ,15 4. .14 E l k Creek - — — — — — -- — — — — Salmon R i v e r - — — — — — — — — — — 11.0 Chehalis Lake 10. 9 0. .60 68. .5 71. ,4 4. .23 4. .27 E l k Creek 11. 0 0. .17 68. .1 — — 4. .22 — — Salmon River 10. 9 0. .26 61. .4 62. .4 4. .12 4. .13 8.0 Chehalis Lake 8. 0 0. .23 108. .6 106. .3 4. .69 4. .67 E l k Creek 8. 0 0. .24 95. .8 — — 4. .56 — — Salmon R i v e r 8. 0 0, .10 90. .1 90. .3 4. ,50 4. .50 5.0 Chehalis Lake 5. 0 0. .16 155. .2 155. .5 5. .04 5. .05 E l k Creek 5. 1 0. .49 137. .6 — — 4. ,92 — — Salmon R i v e r 5. 1 0. .56 140. ,2 140. .6 4. .94 4. .95 2.0 Chehalis Lake 2. 2 0. .73 223. .4 224. .0 5. ,41 5. .41 E l k Creek 2. 0 0, .55 267. .6 — — 5. ,59 — — Salmon R i v e r 2. 0 0. .49 198. .9 197. .8 5. .29 5. .39 51 FIGURE 10 Influence of temperature on 50 percent emergence time i n three coho salmon populations (Chehalis Lake, E l k Creek and Salmon R i v e r ) . 5 2 i i i i i i i i i i i i i r n 0 2 4 6 8 10 12 14 T E M P E R A T U R E °C J 53 Table 13. The r e g r e s s i o n equations to 50 percent emergence, c o r r e l a t i o n c o e f f i c i e n t s , and degree of freedom f o r three coho salmon populations. L o c a t i o n Regression equation to 50 percent emergence C o r r e l a t i o n Degrees of c o e f f i c i e n t freedom Chehalis Lake In E 5.594 - 0.112 T r - 0.987 Elk Creek l n E 5.789 - 0.149 T r - 0.985 Salmon R i v e r l n E 5.569 - 0.132 T r - 0.999 54 Table 14. Mean lengths and mean weights of coho salmon a l e v i n s incubated at constant temperatures. Target temperature Length_(mm) Weight (g) (°C) Female n x SD x SD 14.0 Chehalis Lake 1 15 16, .23 0. 552 0, .20 0. 021 2 15 15, .00 0. 517 0, .15 0. 019 E l k Creek 1 — — — — — — — Salmon R i v e r 1 2 — — — — — — — 11.0 Chehalis Lake 1 15 17. .06 0. 633 0, .20 0. 022 2 15 15. .84 0. 415 0. .15 0. 018 E l k Creek 1 15 16. ,66 0. 545 0, .12 0. 007 Salmon R i v e r 1 15 16. .97 0. 511 0. .22 0. 019 2 15 16. .95 0. 475 0. .20 0. 021 8.0 Chehalks Lake 1 15 18. ,15 0. 530 0. .19 0. 023 2 15 16. ,57 0. 491 0. .14 0. 012 E l k Creek 1 15 17. .35 0. 381 0. .13 0. 009 Salmon R i v e r 1 15 18. .87 0. 415 0. .21 0. 019 2 15 17. .76 0. 453 0. .21 0. 020 5.0 Chehalis Lake 1 15 17. ,41 0. 815 0. .18 0. 021 2 15 15. ,78 0. 675 0. .13 0. 020 E l k Creek 1 15 16. ,26 0. 538 0. .12 0. 011 Salmon R i v e r 1 15 18. ,19 0. 435 0. .22 0. 018 2 15 18. ,09 0. 689 0. ,20 0. 019 2.0 Chehalis Lake 1 15 19. ,24 0. 410 0. ,19 0. 023 2 15 18. ,29 0. 590 0. ,15 0. 022 El k Creek 1 15 15. ,88 0. 896 0. .13 0. 013 Salmon R i v e r 1 15 19. ,98 0. 435 0. ,22 0. 021 2 15 19. ,75 0. 620 0. ,21 0. 019 55 (Duncan's run t e s t ) suggests there are four homogeneous subsets i n the data (Chehalis $ 2; E l k Creek °- 1; Chehalis £ 1; Salmon ¥ 2; and Salmon $ 1). The longest a l e v i n s were produced by Salmon ¥ 1 and the s h o r t e s t by Chehalis ¥ 2 ( F i g . 11). This r e s u l t i s s i m i l a r to the r e s u l t obtained f o r egg s i z e . A n a l y s i s of variance shows that mean a l e v i n length i s a f f e c t e d by temperature (F r a t i o = 185.1, DF = 4,311, p <0.05), and there i s s i g n i f i c a n t i n t e r a c t i o n between females and temperature (F r a t i o = 8.1, DF = 11,311, p <0.05). Comparison of means (Duncan's run t e s t ) i n d i c a t e s that the a l e v i n s produced by both Chehalis Lake females have the same response to temperature. There are four homogeneous subsets (14°C; 11° and 5°C; 8°C; and 2°C). Salmon Ri v e r coho a l s o respond to i n c u b a t i o n temperature but i n a s l i g h t l y d i f f e r e n t way. There are four homogeneous subsets f o r Salmon £ 1 (11°C; 5°C; 8°C; and 2°C) and three homogeneous subsets f o r Salmon ? 2 (11°C; 8° and 5°C; and 2°C). The general trend i s f o r Chehalis Lake and Salmon R i v e r coho to increase i n a l e v i n l e n g t h as i n c u b a t i o n temperatures decrease. The longest a l e v i n s are produced at low temperatures (2°C) and the s h o r t e s t at high temperatures (14°C). E l k Creek coho respond to temperature i n a d i f f e r e n t way ( F i g . 11). There are three homogeneous subsets (2° and 5°C; 11°C; and 8°C). The longest a l e v i n s are produced at 8°C and the s h o r t e s t at 2°C. This i s the reverse of the trend f o r Chehalis Lake and Salmon R i v e r a l e v i n s . Table 14 a l s o i n d i c a t e s that Chehalis Lake a l e v i n s have s i m i l a r weights at 2°, 8° and 14°C and are only s l i g h t l y l i g h t e r at 5°C. E l k Creek and Salmon River a l e v i n s have s i m i l a r weights at a l l temperatures. In a d d i t i o n , Table 14 suggests that the o v e r a l l d i f f e r e n c e s i n both a l e v i n length and weight among females r e s u l t s from i n i t i a l egg s i z e d i f f e r e n c e s . The mean lengths and mean weights of coho f r y incubated at each tempera-56 FIGURE 11 Influence of temperature on mean a l e v i n length i n three coho salmon populations (Chehalis Lake, E l k Creek and Salmon R i v e r ) . 57 C H E H A L I S L A K E F E M A L E 1 C H E H A L I S L A K E F E M A L E 2 E L K C R E E K F E M A L E 1 S A L M O N R I V E R F E M A L E 1 S A L M O N R I V E R F E M A L E 2 58 ture f o r each female are presented i n Table 15. A n a l y s i s of variance i n d i c a t e s that the o v e r a l l mean lengths of f r y produced by each female are d i f f e r e n t (F r a t i o = 171.3, DF 4,311, p <0.05). A n a l y s i s of the o v e r a l l means (Duncan's run t e s t ) suggests that there are f i v e homogeneous subsets ( E l k Creek ¥ 1; Chehalis $ 2; Chehalis ? 1; Salmon $ 2; and Salmon ¥ 1). The longest f r y are produced by Salmon ¥ 1 and the s h o r t e s t by E l k Creek ? 1 ( F i g . 12). The a n a l y s i s a l s o i n d i c a t e s that f r y l e n g t h i s a f f e c t e d by temperature (F r a t i o = 95.0, DF = 4,311, p <0.05) and that there i s s i g n i f i -cant i n t e r a c t i o n between females and temperature (F r a t i o = 7.3, DF = 11,311, p <0.05). Comparison of means (Duncan's run t e s t ) suggests that f r y produced by both Chehalis Lake females have a s i m i l a r response to temperature. There are three homogeneous subsets (14°C; 11° and 2°C; and 5° and 8°C). The longest f r y are produced at 8°C and the s h o r t e s t at 14°C. Fry produced by both Salmon R i v e r females a l s o have s i m i l a r responses to temperature but they are s l i g h t l y d i f f e r e n t than the response of Chehalis Lake f r y . There are only two homogeneous subsets (11°, 2° and 5°C; and 8°C). The f r y produced at 2°, 5° and 11°C are of s i m i l a r l e n g t h s , but they are sh o r t e r than f r y produced at 8°C. Comparison of means f o r E l k Creek f r y i n d i c a t e s that i n c u b a t i o n temperature has no e f f e c t on the mean len g t h of f r y . Table 15 a l s o i n d i c a t e s that the general trend i s f o r f r y weight and l e n g t h to decrease at extreme temperatures (2° and 14°C). CHINOOK SALMON: The chinook salmon eggs from the Babine R i v e r counting fence were taken from s e v e r a l females. Egg diameter ranged from 7.9 to 9.5 mm (mean = 6.7 mm; 59 Table 15. Mean lengths and mean weights of coho salmon f r y incubated at constant temperatures. Target Length (mm) Weight (g) temperature _ (°C) Female n x SD x SD 14.0 Chehalis Lake 1 15 24. .16 1. .305 0, .25 0. 016 2 15 23. .32 0. .560 0, .23 0. 014 E l k Creek 1 — — — — — — Salmon R i v e r 1 2 — — — — — — 11.0 Chehalis Lake 1 15 25. .59 0. .997 0, .27 0. 017 2 15 25. .21 0. .805 0, .22 0. 013 E l k Creek 1 15 24. .49 0. .386 0, .21 0. 012 Salmon R i v e r 1 15 26, .90 0. .555 0. .34 0. 020 2 15 26. .57 0. .372 0. .33 0. 022 8.0 Chehalis Lake 1 15 27, .97 0. .790 0. .32 0. 028 2 15 25, .96 0, .840 0. .27 0. 019 E l k Creek 1 15 24, .75 0. .474 0, .22 0. 014 Salmon River . 1 15 28. .57 0, .599 0. .38 0. 021 2 15 27, .07 0. .482 0. .37 0. 029 5.0 Chehalis Lake 1 15 27. .43 1. .034 0. .33 0. 018 2 15 26, .13 0. .465 0, .30 0. 020 E l k Creek 1 15 24. .89 0. .798 0, .27 0. 013 Salmon River 1 15 27, .64 0. .599 0. .41 0. 023 2 15 27. .07 0. .697 0, .41 0. 030 2.0 Chehalis Lake 1 15 25, .45 0, .879 0. .27 0. 015 2 15 25. .07 0. .684 0. .23 0. 021 E l k Creek 1 15 24, .20 0, .751 0. .23 0. 014 Salmon R i v e r 1 15 27. .59 0. .808 0. .34 0. 022 2 15 26, .81 1, .000 0. .35 0. 030 60 FIGURE 12 Influence of temperature on mean f r y length three coho salmon populations (Chehalis Lake E l k Creek and Salmon R i v e r ) . 61 • C H E H A L I S L A K E F E M A L E 1 • C H E H A L I S L A K E F E M A L E 2 • E L K C R E E K F E M A L E 1 A S A L M O N R I V E R F E M A L E 1 A S A L M O N R I V E R F E M A L E 2 62 SD = 0.93 mm; n = 100). The mean weight of preserved f e r t i l i z e d eggs was 0.38 g (SD = 0.019 g). Apparently about 20 percent of the eggs were / i n f e r t i l e (showed no evidence of development). Temperature and S u r v i v a l : Figure 13 shows the s u r v i v a l of chinook eggs to completion of hatching and emergence. Zygote s u r v i v a l was high (90-95 percent) at 5°, 8° and 11°C but decreased to 49 percent at 14°C. At 2°C few eggs (4 percent) s u r v i v e d . At 8 , ir and 14 C most m o r t a l i t y occurred at hatching; however, at 5 C death occurred at the eye pigmentation stage, and at 2°C the embryos died at b l a s t o d i s c c l o s u r e . A l e v i n s u r v i v a l decreased (2 to 5 percent) at 8 , 11 and 14 C; the a l e v i n s died j u s t a f t e r hatching. No a l e v i n s died at 2° and 5°C. Temperature and Development Rate: I Development times f o r Babine River chinook salmon incubated at constant temperatures are presented i n Table 16. The r e g r e s s i o n of hatching time on temperature ( F i g . 14) i s described by the equation l n D = 5.417 - 0.136 T. The c o r r e l a t i o n c o e f f i c i e n t i s -0.977. Regression a n a l y s i s i n d i c a t e s an in v e r s e r e l a t i o n s h i p between hatching time and temperature (F c a l = 1186.9, F tab (1, 2; 0.05) = 18.5) and that there i s s i g n i f i c a n t curvature (F c a l = 53.9, F tab (1, 2; 0.05) = 18.5). The times r e q u i r e d f o r 50 percent of the chinook f r y to emerge at each temperature are presented i n Table 17. The equation l n E = 5.945 - 0.135 T describes the r e g r e s s i o n of emergence time on temperature ( F i g . 15). The c o r r e l a t i o n c o e f f i c i e n t i n -0.991. Regression a n a l y s i s suggests an i n v e r s e 63 FIGURE 13 Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d chinook salmon eggs (Babine R i v e r ) . 6k • H A T C H I N G O E M E R G E N C E 20 H ® 1 I I I 1 I I I I I I | I 1 2 4 6 8 10 12 14 T E M P E R A T U R E °C 65 Table 16. Days to 50 percent hatching f o r chinook salmon (Babine R i v e r ) incubated at constant temperature. Target temperature (°C) Incubation temperature _ (°C) x SD Days to 50 percent hatching l n Days to 50 percent hatching 14.0 14.0 0.10 38.4 3.65 11.0 11.4 1.20 46.9 3.85 8.0 8.1 0.85 67.1 4.21 5.0 5.3 1.30 101.5 4.62 2.0 2.1 0.97 202.0 5.31 66 FIGURE 14 Influence of temperature on 50 percent hatching time i n chinook salmon (Babine R i v e r ) . i 67 68 Table 17. Days to 50 percent emergence for chinook salmon; (Babine River) incubated at constant temperatures. Target temperature (°C) Incubation temperature (°C) SD Days to 50 percent emergence In Days to 50 percent emergence 14.0 14.0 0.35 63.0 4.14 11.0 11.3 1.00 84.0 4.43 8.0 8.1 0.70 115.0 4.75 5.0 5.2 , 1.02 191.0 5.25 2.0 2.0 0.85 316.0 5.76 69 FIGURE 15 Influence of temperature on 50 percent emergence time i n chinook salmon (Babine Ri v e r ) . 70 71 r e l a t i o n s h i p between emergence time and i n c u b a t i o n temperature (F c a l = 1650.8, F tab (1, 2; 0.05) = 18.5), and s i g n i f i c a n t curvature (F c a l = 28.1, F tab (1, 2; 0.05) = 18.5). The slopes of the emergence and hatching r e g r e s s i o n l i n e s are homogen-eous (F c a l = 0.1, F tab (1, 5; 0.05) = 6.6). This s i m i l a r i t y i n slope i n d i c a t e s temperature has the same e f f e c t on pre-hatching and post-hatching development r a t e s . Temperature and S i z e : The mean lengths and weights of chinook a l e v i n s incubated at each temperature are presented i n Table 18. Constant temperature has a s i g n i f i c a n t e f f e c t on the mean length of a l e v i n s produced at hatching (F r a t i o = 17.55, DF = 3,56, p <0.05). A comparison of means (Duncan's run t e s t ) suggests there are three homogeneous subsets (11° and 14°C; 5°C; and 8°C). There are no r e s u l t s f o r s i z e at hatching at 2°C because s u r v i v a l was low and the a l e v i n s were needed to determine the r a t e of development to emergence. The longest a l e v i n s are produced at 8°C and the s h o r t e s t at 11° and 14°C. A l e v i n weight shows the same p a t t e r n of change w i t h temperature as l e n g t h . Table 19 presents the mean lengths and weights of chinook f r y incubated at each temperature. A n a l y s i s of v a r i a n c e i n d i c a t e s that temperature a f f e c t s mean f r y length at emergence (F r a t i o = 534.0, DF = 4,70, p <0.05). When mean lengths are compared f o r d i f f e r e n t temperatures (Duncan's run t e s t ) there are three homogeneous subsets (14°C; 8°, 11° and 2°C; and 5°C). The longest f r y are produced at 5°C; intermediate, s i m i l a r s i z e d f r y are produced at 2°, 8° and 11°C; and the s h o r t e s t f r y are produced at 14°C. Table 19 a l s o shows chinook f r y at 11° and 14°C are s l i g h t l y heavier than f r y at 2° and 8 C. The h e a v i e s t f r y are produced at 5 C. 72 Table 18. Mean lengths and weights of chinook salmon a l e v i n s (Babine R i v e r ) incubated at constant temperatures. Target temperature (°C) n x SD x SD Length (mm) Weight (g) 14.0 15 18.66 0.481 0.34 0.019 11.0 15 18.50 0.537 0.35 0.027 8.0 15 20.09 0.614 0.37 0.021 5.0 15 19.37 0.572 0.30 0.026 73 Table 19. Mean lengths and mean weights of chinook salmon f r y (Babine R i v e r ) incubated at constant temperatures. Target temperature ^Length (mm) ^Weight (g) (°C) n x SD x SD 14.0 15 27.29 0.356 0.47 0.023 11.0 15 28.56 0.584 0.49 0.017 8.0 15 28.48 0.494 0.45 0.021 5.0 15 30.74 0.845 0.53 0.030 2.0 15 28.99 0.839 0.44 0.027 74 PINK SALMON: The pink salmon eggs were from a sing l e Chilliwack River female. Egg diameter ranged from 6.8 to 7.9 mm (mean = 7.2 mm; SD = 0.21 mm; n = 100). The mean weight of preserved, f e r t i l i z e d eggs was 0.20 g (SD = 0.084 g). Apparently most of the eggs were f e r t i l e (only two percent showed nq evidence of development). Temperature and S u r v i v a l : Figure 16 shows s u r v i v a l to completion of hatching and emergence of pink salmon eggs and al e v i n s . For Chilliwack River pink salmon zygotes s u r v i v a l was high (93 to 97 percent) at intermediate temperatures (5°, 8° and 11°C), moderate (51 percent) at 14°C, and zero at 2°C. At intermediate temperatures (5 , 8 and 11 C) death occurred at hatching; however, at 14 C most zygotes died during eye pigmentation, and at 2°C death occurred early i n development (blastopore c l o s u r e ) . At 5° and 8°C there were no deaths between hatching and emergence; however, at 11° and 14°C some alevins died ( F i g . 16) before emergence. Temperature and Development Rate: Development times f o r pink salmon eggs incubated at constant.temperatures are presented i n Table 20. Regression analysis indicates an inverse r e l a t i o n -ship between development rate and temperature (F c a l = 17691.8; F tab (1, 1; 0.05) = 161.4). The regression of development time on temperature ( F i g . 17) i s described by the equation l n D = 4.917 - 0.082 T. The c o r r e l a t i o n c o e f f i c i e n t i s -0.976 and a test f o r curvature i s s i g n i f i c a n t (F c a l = 889.5; F tab (1, 1; 0.05) = 161.4). 75 FIGURE 1 6 Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d pink salmon eggs (Chilliwack R i v e r ) . 76 • H A T C H I N G O E M E R G E N C E 77 Table 20. Days to 50 percent hatching f o r pink salmon ( C h i l l i w a c k R i v e r ) incubated at constant temperatures. Target Incubation Days to l n Days to temperature temperature 50 percent 50 percent (°C) (°C) hatching hatching x SD 14.0 13.9 0.30 46.2 3.83 11.0 11.0 0.13 52.4 3.96 8.0 8.0 0.47 66.6 4.20 5.0 5.1 0.68 96.6 4.57 2.0 2.2 0.91 78 FIGURE 17 Influence of temperature on 50 percent hatching time i n pink salmon ( C h i l l i w a c k R i v e r ) . 79 80 The times required for pink salmon alevins to emerge at constant temper-atures are presented i n Table 21. Regression analysis using the equation l n E = 5.321 - 0.059 T ( F i g . 18) suggests an inverse r e l a t i o n s h i p between 50 percent emergence time and incubation temperature (F c a l = 780.0; F tab (1, 1; 0.05) = 161.4). The c o r r e l a t i o n c o e f f i c i e n t i s -0.953 and a test f or curvature i s not s i g n i f i c a n t (F c a l = 11.4; F tab (1, 1; 0.05) = 161.4). S i m i l a r i t i e s i n the emergence and hatching regression l i n e s indicate temperature does have the same e f f e c t on pre-hatching and post-hatching development rates (F c a l = 4.8; F tab (1, 4; 0.05) = 7.7). Temperature and Size: The mean lengths and weights of pink salmon alevins hatched at each constant temperature are presented i n Table 22. These data ind i c a t e that incubation temperature a f f e c t s the length of newly hatched alevins (F r a t i o = 42.72; DF = 3,56; p <0.05). When mean lengths are compared for d i f f e r e n t temperatures (Duncan's run test) there are three homogeneous subsets (14°C; 11°C; 8° and 5°C). The longest alevins are produced at 5°C and the shortest at 14°C. There i s a general trend for a l e v i n length to increase as temperatures decrease. Table 22 also indicates a l e v i n weight i s s i m i l a r at a l l temperatures. Table 23 presents the mean lengths and weights of pink salmon f r y incubated at constant temperatures. These data ind i c a t e that the length of f r y at emergence i s affected by incubation temperature (F r a t i o = 37.96, DF = 3,56, p <0.05). A Duncan't run test comparing mean f r y lengths suggests three homogeneous subsets (14°C; 5° and 11°C; and 8°C). The longest f r y are produced at 8°C and the shortest at 14°C. The pattern for f r y length i s not 81 Table 21. Days to 50 percent emergence f o r pink salmon ( C h i l l i w a c k R i v e r ) incubated at constant temperatures. Target Incubation Days to In Days to temperature temperature 50 percent 50 percent (°C) (°C) emergence emergence x SD 14.0 13.9 0.27 96.0 4.56 11.0 11.0 0.10 98.0 4.58 8.0 8.0 0.35 124.2 4.82 5.0 5.1 0.56 160.7 5.08 82 FIGURE 18 Influence of temperature on 50 percent emergence time i n pink salmon X C h i l l i w a c k R i v e r ) . 83 ^ 6 .0 - j cu ~o c 84 Table 2 2 . Mean lengths and mean weights of pink salmon a l e v i n s ( C h i l l i w a c k R i v e r ) incubated at constant temperatures. Target Length (mm) Weight (g) temperature (°C) n x SD x S 1 4 . 0 1 5 1 5 . 7 9 0 . 6 6 1 0 . 1 6 0 . 0 1 4 1 1 . 0 1 5 1 6 . 8 0 0 . 4 3 9 0 . 1 7 0 . 0 1 9 8 . 0 1 5 1 7 . 5 3 0 . 4 8 8 0 . 1 7 0 . 0 1 3 5 . 0 1 5 1 7 . 8 0 0 . 5 0 4 0 . 1 6 0 . 0 1 6 85 Table 23. Mean lengths and mean weights of pink salmon f r y (Chilliwack River) incubated at constant temperatures. Target Length (mm) Weight (g) temperature (°C) n x SD x SD 14.0 15 25.98 0.546 0.22 0.018 11.0 15 27.07 0.497 0.25 0.014 8.0 15 28.37 0.403 0.27 0.021 5.0 15 26.80 0.827 0.27 0.019 86 the same as the p a t t e r n f o r a l e v i n l e n g t h . Fry produced at 5°C are not longer than those produced at 8°C. The general trend i s f o r f r y length to decrease at extreme i n c u b a t i o n temperatures (5° and 14°C). Table 23 a l s o . i n d i c a t e s mean f r y weight increases as in c u b a t i o n temperatures decrease. The l i g h t e s t f r y are,produced at 14°C and the heaviest a t 5°C. SOCKEYE SALMON: The sockeye salmon eggs from Weaver Creek were from a s i n g l e female. Egg diameter ranged from 4.9 to 6.1 mm (mean = 5.4 mm; SD = 0.21 mm; n = 100). The mean weight of preserved, f e r t i l i z e d eggs was 0.13 g (SD = 0.013 g). A l l of the eggs were f e r t i l e . Temperature and S u r v i v a l : Figure 19 shows s u r v i v a l of sockeye salmon eggs and a l e v i n s to comple-t i o n of hatching and emergence. Zygote s u r v i v a l was about 10 percent a t 11° and 14°C, and 40 percent at 2° and 5°C. The highest zygote s u r v i v a l (79 percent) was at 8°C. At a l l temperatures most of the embryos died during blastopore c l o s u r e ; however, at 11° and 14°C some embryos died at hatching, and at 5°C some died at the eye pigmentation stage. No a l e v i n s died at 5°, 8° and 11°C, but at the extreme temperatures (2° and 14°C) some a l e v i n s d i e d . Temperature and Development Rate: Table 24 presents the times r e q u i r e d f o r sockeye salmon to hatch when incubated at constant temperatures. Regression a n a l y s i s suggests there i s an in v e r s e r e l a t i o n s h i p between hatching times and temperature (F c a l = 566.4; F tab (1, 2; 0.05) = 18.5). The r e g r e s s i o n l i n e i s described by the equation 87 FIGURE 19 Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l -i z e d sockeye salmon eggs (Weaver Creek). 88 • H A T C H I N G O E M E R G E N C E 1 0 0 — 1 8 0 < > > 6 0 cr D C/) z UJ 4 0 O ct: UJ CL 2 0 H • r 2 i I i TT 8 4 6 T E M P E R A T U R E 1 ' 1 1 1 10 1.2 14 o_ 89 Table 24. Days to 50 percent hatching f o r sockeye salmon (Weaver Creek) incubated at constant temperatures. Target temperature (°C) Incubation temperature (°C) x SD Days to 50 percent hatching In Days to 50 percent hatching 14.0 11.0 8.0 5.0 2.0 13.9 11.2 7.9 5.1 2.1 0.61 0.73 0.42 0.90 0.50 47.0 51.8 76.9 119.5 206.4 3.85 3.95 4.34 4.78 5.33 90 l n D = 5.463 - 0.127 T ( F i g . 20). The c o r r e l a t i o n c o e f f i c i e n t i s -0.977. There i s also s i g n i f i c a n t curvature (F c a l = 25.0, F tab (1, 2; 0.05) = 18.5). The times required f o r sockeye f r y to emerge at constant temperatures are presented i n Table 25. The equation 1 n E = 5.774 - 0.113 T describes the regression of emergence times on temperature ( F i g . 21). The c o r r e l a t i o n c o e f f i c i e n t i s -0.988. Regression analysis suggests both an inverse r e l a t i o n s h i p between emergence time and temperature (F c a l = 6469.6, F tab (1, 2; 0.05) = 18.5) and s i g n i f i c a n t curvature (F c a l = 149.7, F tab (1, 2; 0.05) = 18.5). The slopes of the emergence and hatching regression l i n e s are homogen-eous (F c a l = 4.7, F tab (1, 5; 0.05) = 6.6). This s i m i l a r i t y i n slope indicates temperature has the same e f f e c t on pre-hatching and post-hatching development rates. Temperature and Size: The mean lengths and weights of sockeye alevins incubated at each temperature are presented i n Table 26. Constant incubation temperatures a f f e c t the length of alevins at hatching (F r a t i o = 58.4, DF = 4,70, p <0.05). A comparison of means (Duncan's run test) suggests there are four homogeneous subsets (14°C; 11° and 5°C; 8°C; and 2°C). The longest alevins are produced at 2°C and the shortest at 14°C. The general trend i s for a l e v i n length to increase as incubation temperatures decrease. Table 26 indicates a l e v i n weight shows the same pattern of change with temperature as length. Table 27 gives the mean lengths and weights of sockeye f r y incubated at each temperature. Analysis of variance suggests that temperature a f f e c t s the 91 FIGURE 20 Influence of temperature on 50 percent hatching time i n sockeye salmon (Weaver Creek). 92 ( 93 Table 25. Days to 50 percent emergence f o r sockeye salmon (Weaver Creek) incubated at constant temperatures, Target Incubation Days to l n Days to temperatures temperature 50 percent 50 percent (°C) (°C) emergence emergence x SD 14.0 13.8 0.71 72.0 4.28 11.0 11.3 0.47 90.3 4.50 8.0 8.1 0.54 120.5 4.79 5.0 5.2 0.83 173.0 5.15 2.0 2.1 0.66 282.2 5.64 94 FIGURE 21 Influence of temperature on 50 percent emergence time i n sockeye salmon (Weaver Creek). 95 96 Table 26. Mean lengths and mean weights of sockeye salmon a l e v i n s (Weaver Creek) incubated at constant temperatures. T a r g e t Length (mm) Weight (g) temperature _ _ (°C) n x SD x SD 14.0 15" 15.13 11.0 15 16.09 8.0 15 17.10 5.0 15 16.16 2.0 15 17.84 0.524 0.10 0.020 0.329 0.11 0.019 0.451 0.12 0.015 0.817 0.11 0.017 0.466 0.12 0.013 97 mean l e n g t h of f r y a t emergence (F r a t i o = 53.0, DF = 4,70, p <0.05). A comparison of means (Duncan's run t e s t ) i n d i c a t e s four homogeneous subsets (14°C; 11° and 5°C; 5° and 2°C; and 8°C). Fry incubated at 2°, 5° and 11°C are s i m i l a r i n l e n g t h . The longest f r y are produced at 8°C and the s h o r t e s t at 14°C. The general trend i s f o r f r y length to increase up to intermediate i n c u b a t i o n temperatures and then to decrease w i t h i n c r e a s i n g temperatures. Table 27 shows that mean f r y weight increases as temperature decreases. The l i g h t e s t f r y are produced at 14°C and the heaviest at 2°C. CHUM SALMON: The chum salmon eggs from Weaver Creek were from a s i n g l e female. Egg diameter ranged from 7.5 to 8.5 mm (mean = 8.0 mm; SD = 0.23 mm; n = 100). The mean weight of preserved, f e r t i l i z e d eggs was 0.26 g (SD - 0.015 g). A l l the eggs were f e r t i l e . Temperature and S u r v i v a l : Figure 22 shows s u r v i v a l of chum salmon eggs and a l e v i n s to completion of hatching and emergence. Zygote s u r v i v a l was about 67 percent at 8 U, 11" and 14°C. At 5°C s u r v i v a l decreased to 58 percent, and at 2°C s u r v i v a l was zero. At 2°C death occurred during blastopore c l o s u r e , but at 8°C the embryos tended to d i e l a t e r i n development ( j u s t a f t e r eye pigmentation). At 5°, 11° and 14°C m o r t a l i t y was highest j u s t before and during hatching. A f t e r hatching the a l e v i n s continued to d i e at 5°, 11° and 14°C. A l e v i n m o r t a l i t y was greater (10 and 15 percent) at 11° and 14°C than at 5°C (3 p e r c e n t ) . 98 Table 27. Mean lengths and mean weights of sockeye salmon f r y (Weaver Creek) incubated at constant temperatures. T a r g e t Length (mm) Weight (g) temperature (°C) n x SD x SI 14.0 15 20.73 0.726 0.13 0.021 11.0 15 22.90 0.994 0.16 0.019 8.0 15 24.43 0.613 0.17 0.017 5.0 15 23.39 0.767 0.17 0.022 2.0 15 23.59 0.769 0.18 0.017 99 V FIGURE 22 Incubation temperature and percent s u r v i v a l to completion of hatching and emergence of f e r t i l i z e d chum salmon eggs (Weaver Creek). 100 • H A T C H I N G O E M E R G E N C E 100—1 20 i — r ® i | i | i—i—i—i—I I I I 0 2 4 6 8 10 12 14 T E M P E R A T U R E °C 101 Temperature and Development Rate: The times required for chum salmon to hatch at constant temperatures i s presented i n Table 28. The regression equation i s l n D = 5.104 - 0.105 T (Fig. 23), and the regression c o e f f i c i e n t i s -0.988. A test f o r curvature was not s i g n i f i c a n t (F c a l = 0.0, F tab (1, 1; 0.05) = 161.4). Regression analysis i n d i c a t e s an inverse r e l a t i o n s h i p between development rate to hatching and incubation temperature (F c a l = 756.0; F tab (1, 1; 0.05) = 161.4). Times (to 50 percent emergence) for chum salmon incubated at constant temperatures are presented i n Table 29. Regression analysis indicates 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 emergence time and temperature (F c a l = 4728.9; F tab (1, 1; 0.05) - 161.4). The regression of emergence on temperature ( F i g . 24) i s described by the equation l n E = 5.603 - 0.097 T. The c o r r e l a t i o n c o e f f i c i e n t i s -0.994. There i s s i g n i f i c a n t curvature present (F c a l = 565.3; F tab (1, 1; 0.05) = 161.4). S i m i l a r i t i e s i n the slopes of the emergence and hatching l i n e s i n d i c a t e temperature has the same e f f e c t on pre-hatching and post-hatching development rates (F c a l = 1.4; F tab (1, 4; 0.05) = 7.7). Temperature and Size: Table 30 presents the mean lengths and weights of chum alevins incubated at constant temperatures. Analysis of variance i n d i c a t e s that incubation temperatures have an e f f e c t on the length of alevins at hatching (F r a t i o = 18.2, DF = 3,56; p <0.05). Comparison of mean lengths for d i f f e r e n t temperatures (Duncan's run test) suggest there are two homogeneous subsets (8°, 5° and 11°C; and 14°C). The 5°, 8° and 11°C alevins are of s i m i l a r 102 Table 28. Days to 50 percent hatching f o r chum salmon (Weaver Creek) incubated at constant temperatures. Target temperature (°C) Incubation temperature (°C) x SD Days to 50 percent hatching l n Days to 50 percent hatching 14.0 13.9 0.61 39.8 3.68 11.0 11.2 0.73 47.2 3.85 8.0 7.9 0.42 72.2 4.28 5.0 5.1 0.90 99.0 4.59 2.0 2.1 0.50 y 103 FIGURE 23 Influence of temperature on 50 percent hatching time i n chum salmon (Weaver Creek). 1 0 V 105 Table 29. Days to 50 percent emergence f o r chum salmon (Weaver Creek) incubated at constant temperatures. Target Incubation Days to l n Days to temperature temperature 50 percent 50 percent (°C) (°C) emergence emergence x SD 14.0 13.8 0.71 72.1 4.28 11.0 11.3 0.47 90.8 4.51 8.0 8.1 0.54 120.2 4.79 5.0 5.2 0.83 173.5 5.15 106 FIGURE 24 Influence of temperature on 50 percent emergence time i n chum salmon (Weaver Creek). 107 108 Table 30. Mean lengths and mean weights of chum salmon alevins (Weaver Creek) incubated at constant temperatures. Tarset Length (mm) Weight (g) temperature " 6 B (°C) n x SD x SD 14.0 15 19.19 0.523 0.22 0.018 11.0 15 17.95 0.935 0.23 0.015 8.0 15 16.90 0.608 0.23 0.017 5.0 15 17.50 0.612 0.22 0.019 109 \ / length but shorter than those produced at 14 C. The general trend i s for al e v i n length to increase as incubation temperatures increase. The mean weight of alevins incubated at extreme temperatures (5° and 14°C) i s s l i g h t l y l i g h t e r than those incubated at 8° and 11°C. The mean lengths and weights of Weaver Creek chum f r y incubated at constant temperatures are presented' i n Table 31. Analysis of variance suggests that incubation temperatures a f f e c t f r y length at emergence (F r a t i o = 7.7, DF = 3,56, p <0.05). A comparison of means (Duncan's run test) indicates there are three homogeneous subsets (14° and 8°C; 8° and 11°C; and 11° and 5°C). The longest f r y are produced at 5°C and the shortest at 14°C. This i s the reverse of the r e s u l t s obtained at hatching. At emergence the general trend i s for f r y length to increase as incubation temperatures decrease. Table 31 also indicates f r y weight increases as incubation temperatures decrease. The l i g h t e s t f r y are produced at 14°C and the heaviest at 5°C. VARYING TEMPERATURE REGIMES RAINBOW TROUT: The rainbow trout eggs used i n these experiments came from the same years and the same females as those i n the constant temperature experiments (Table 4). The success of egg f e r t i l i z a t i o n followed the same pattern as that i n the constant temperature experiments. 110 Table 31. Mean lengths and mean weights of chum salmon f r y (Weaver Creek) incubated at constant temperatures. T a r g e t Length (mm) , Weight (g) temperature (°C) n x SD x SD 14.0 15 29.98 1.062 0.30 0.027 11.0 15 31.00 1.017 0.33 0.021 8.0 15 30.36 1.224 0.36 0.023 5.0 15 31.37 0.891 0.44 0.030 I l l Temperature and S u r v i v a l : Zygote s u r v i v a l to completion of hatching, and f r y s u r v i v a l to completion of emergence, for each varying temperature regime are given i n Table 32. In 1976 s u r v i v a l was d i f f e r e n t f o r each varying temperature regime. Under the f a l l temperature regime (14°C and down) s u r v i v a l was 37 percent, and under the spring (5°C and up) regime s u r v i v a l was 58 percent. With the f a l l regime death occurred mainly at blastopore closure, and with the spring regime the alevins died at hatching. For both regimes a decrease i n s u r v i v a l occurred j u s t a f t e r hatching. The experiments were repeated i n 1977 using eggs from separate females. In 1977 zygote s u r v i v a l was high for eggs from a l l three females under both temperature regimes. Again, with the f a l l regime those zygotes that died tended to die at blastopore closure, while with the spring regime death occurred at hatching. There was no decrease i n s u r v i v a l f o r medium and small eggs incubated under e i t h e r regime; however, 63 percent,of the large eggs survived under the f a l l regime. The large egg mortality occurred j u s t a f t e r hatching. Temperature and Development Rate: The actual and predicted times for development to 50 percent hatching under both varying temperature regimes are presented i n Table 33. The . predicted times were determined by using the mean incubation temperature for each regime and the hatching regression equation f o r rainbow trout ( l n D = 4.860 - 0.143 T). There i s l i t t l e d ifference between the predicted and actual r e s u l t s f o r eit h e r regime i n 1976 and among females i n 1977. The actual and predicted times f o r 50 percent emergence under both varying temperature regimes are presented i n Table 34. The predicted times 112 Table 32. Percent s u r v i v a l of f e r t i l i z e d eggs to completion of hatching and emergence f o r rainbow t r o u t (Tunkwa Lake) incubated at v a r y i n g temperature regimes (L = 563.0 mm °-; M = 445.0 mm ¥; S = 289.0 mm?). Percent Percent Temperature s u r v i v a l s u r v i v a l regime Year Female to hatching to emergence F a l l 14°C and down 1976 37.0 21.5 1977 L 97.0 0.0 M 92.6 92.6 S 100.0 100.0 Spring 5°C and up 1976 58.0 52.0 1977 L 81.3 43.4 M 95.4 95.4 S 98.5 98.5 113 Table 33. A c t u a l (A) and p r e d i c t e d (P) days to 50 percent hatching f o r rainbow t r o u t (Tunkwa Lake) incubated at v a r y i n g temperature regimes (L = 563.0 mm M = 445.0 mm £; S = 289.0 mm ¥ ) . Temperature Incubation 50 percent hatching regime Year temperature Female D a y g l n D a y g x . SD A P A P F a l l 14°C and down 1976 10.0 3.24 27.5 30.9 3.31 3.43 1977 10.7 2.17 L 27.6 M 27.5 27.9 3.31 3.33 S 27.0 Spring 5°C and up 1976 9.7 2.81 33.8 32.2 3.52 3.47 1977 9.6 2.95 L 33.8 M 32.1 32.7 3.49 3.48 S 32.5 114 Table 34. A c t u a l (A) and p r e d i c t e d (P) days to 50 percent emergence f o r rainbow t r o u t (Tunkwa Lake) incubated at v a r y i n g temperature regimes (L = 563.0 mm M = 445.0 mm £; S = 289.0 mm ¥) Temperature Incubation 50 percent emergence regime Year temperature Female Days In Days x SD A P A P F a l l 14°C and down 1976 8.1 2.96 66.1 63.9 4.19 4.16 1977 8.3 3.13 L M 60.7 62.2 4.11 4.13 S 60.8 Spring 5°C and up 1976 10.5 3.05 47.2 45.7 3.85 3.82 1977 10.3 3.14 L 47.3 M 47.1 47.0 3.86 3.85 S 47.6 115 were determined by using the mean incubation temperature for each regime of development to emergence and the emergence regression equation f o r rainbow trout ( l n E = 5.292 - 0.140 T). There i s l i t t l e d i f f e r e n c e (Table 34) between the predicted and act u a l r e s u l t s f o r either regime i n 1976 or among females within either regime i n 1977. The differences i n time to emergence between regimes are re l a t e d to differences i n mean development temperatures. Temperature and Size: The mean lengths and weights of rainbow trout alevins incubated under the varying temperature regimes are presented i n Table 35. A comparison of means ( t - t e s t ) indicates that mean a l e v i n length i n 1976 i s not d i f f e r e n t between the two varying temperature regimes. Mean weight i s also s i m i l a r f o r both regimes. The e f f e c t s of the two regimes on the length of alevins produced by females i n 1977 i s not f i x e d . The large female produced the longest alevins under the f a l l regime, but the medium and small females produced the longest alevins under the spring regime. Mean a l e v i n weight f o r each female i s s i m i l a r i n both regimes. Differences i n length and weight among females appear to be re l a t e d to differences i n egg s i z e . ( The mean lengths and weights of rainbow trout f r y incubated with each varying temperature regime are presented i n Table 36. A comparison of means ( t - t e s t ) indicates that the mean length of f r y produced i n 1976, and the f r y produced by the medium female i n 1977, are affected by the varying tempera-ture regimes. In both cases the longest f r y are produced under the f a l l regime and the shortest f r y under the spring regime. There i s no differ e n c e between the mean lengths of f r y produced by the small female (1977) under e i t h e r temperature regime. However, f r y produced i n 1976,'and by the medium 116 Table 35. Mean lengths and mean weights of rainbow t r o u t a l e v i n s (Tunkwa Lake) incubated at v a r y i n g temperature regimes (L = 563.0 mm M = 445.0 mm S = 289.0 mm ?-) . Temperature regime Year Female s i z e n Length X (mm) SD Weight (g) x " SD F a l l 14°C and down 1976 19 12.41 0.974 0.07 0.017 1977 L 26 13.61 0.523 0.08 0.010 M 15 11.72 0.612 0.05 0.019 S 25 11.70 0.325 0.04 0.014 Spring 5°C and up 1976 25 11.89 0.812 0.07 0.019 1977 L 23 13.02 0.643 0.08 0.011 M 14 12.20 0.514 0.05 0.018 S 24 12.55 0.446 0.04 0.017 t-value 1976 1.921 Large -3.513 1977 Medium 2.278 Small 7.386 DF 42 47 27 47 t-prob. 0.059 0.001 0.029 0.000 117 Table 36. Mean lengths and mean weights of rainbow t r o u t f r y (Tunkwa Lake) incubated at v a r y i n g temperature regimes (L = 563.0 mm ?; M = 445.0 mm S = 289.0 mm -i-) . Temperature regime Year Female s i z e n Length (mm) x SD Weight (g) x SD F a l l 14°C and down 1976 26 y 20.59 1.494 0.14 0.017 1977 L — M 13 19.53 0.472 0.12 0.022 S 20 17.26 0.376 0.07 0.016 Spring 5°C and up 1976 23 19.70 1.434 0.12 0.027 1977 L 20 19.77 0.467 0.13 0.019 M 13 17.60 0.720 0.09 0.015 S 22 17.01 0.794 0.07 0.017 1976 Large 1977 Medium Small t-value 2.126 — -6.317 0.965 DF 47 — 24 40 t-prob. 0.036 — 0.000 0.358 118 female i n 1977, are heavier under the f a l l regime than under the sp r i n g regime. Fry produced by the sm a l l female i n 1977 are of s i m i l a r weights under both regimes. COHO SALMON: The coho eggs used i n these experiments came from the same three popula-t i o n s as the eggs i n the constant temperature experiments (Table 9). As before, f e r t i l i z a t i o n was complete. Temperature and S u r v i v a l : S u r v i v a l to completion of hatching and emergence, f o r both temperature regimes, i s given i n Table 37. For Chehalis Lake coho under both regimes s u r v i v a l during development and hatching was high (80 pe r c e n t ) . For E l k Creek s u r v i v a l was 64 percent under the sp r i n g regime and.75 percent under the f a l l regime. In c o n t r a s t , s u r v i v a l among Salmon R i v e r coho zygotes was s t r i k i n g l y d i f f e r e n t between the regimes. Under the s p r i n g regime s u r v i v a l was high (73 to 96 percent) and under the f a l l regime s u r v i v a l was low (zero to 10 percent)'. Death occurred e i t h e r at the eye pigmentation stage or j u s t before hatching under the s p r i n g regime, but under the f a l l regime the eggs died at blastopore c l o s u r e . For E l k Creek coho there was no decrease i n a l e v i n s u r v i v a l under e i t h e r regime. A l e v i n s u r v i v a l d i d decrease s l i g h t l y (6 to 7 percent) i n Salmon R i v e r stock incubated under the sp r i n g regime but there was no decreased s u r v i v a l under the f a l l regime. S u r v i v a l to emergence was d i f f e r -ent f o r each female from Chehalis Lake. There was no decrease i n a l e v i n s u r v i v a l f o r Chehalis £ 1 under the s p r i n g regime and a 27 percent decrease 119 Table 37. Percent s u r v i v a l of f e r t i l i z e d eggs to completion of hatching and emergence for coho salmon incubated at varying temperature regimes. Temperature Percent s u r v i v a l Percent s u r v i v a l regime Female to hatching to emergence F a l l 14°C and down Chehalis Lake 1 80.6 53.5 2 85.0 81.1 Elk Creek 1 75.5 75.0 Salmon River 1 10.8 10.8 2 0.0 0.0 Spring 5°C and up Chehalis Lake 1 85.4 85.4 2 85.6 33.9 Elk Creek 1 64.2 64.2 Salmon River 1 73.0 67.0 2 96.1 89.8 120 under the f a l l regime. The reverse p a t t e r n occurred f o r Chehalis ¥ 2; there was a 4 percent decrease under the f a l l regime and a 51 percent decrease under the sp r i n g regime. For a l l females, under both temperature regimes, m o r t a l i t i e s t y p i c a l l y occurred s h o r t l y a f t e r hatching. Temperature and Development Rate: The a c t u a l and p r e d i c t e d times f o r hatching f o r each v a r y i n g temperature regime are presented i n Table 38. The p r e d i c t e d times were determined by using the mean i n c u b a t i o n temperature and the hatching r e g r e s s i o n equation f o r each coho po p u l a t i o n (Table 12). The r e s u l t s f o r each female w i t h i n a popul a t i o n are s i m i l a r . For both temperature regimes the p r e d i c t e d r e s u l t s f o r C hehalis Lake and E l k Creek coho are c o n s i s t e n t l y higher than the a c t u a l r e s u l t s . Under the f a l l regime the d i f f e r e n c e between the a c t u a l and pr e d i c t e d hatching time f o r Chehalis Lake i s three days and f o r E l k Creek i t i s four days. The d i f f e r e n c e s between the a c t u a l and p r e d i c t e d hatching times under the s p r i n g regime increase f o r Chehalis Lake coho to 12 days and f o r E l k Creek coho to seven days. In c o n t r a s t , the p r e d i c t e d and a c t u a l r e s u l t s f o r Salmon River coho incubated under both regimes are s i m i l a r and only d i f f e r by about one day. Figure 9 shows that the development data f o r Chehalis Lake and E l k Creek coho have more curvature than the Salmon R i v e r coho data. The presence of curvature i n d i c a t e s that the r e g r e s s i o n equations f o r development time to hatching w i l l overestimate at intermediate temperatures. The a c t u a l and p r e d i c t e d times f o r development to emergence under both v a r y i n g temperature regimes are presented i n Table 39. The p r e d i c t e d times were determined by using the mean i n c u b a t i o n temperature and the emergence j 121 Table 38. A c t u a l (A) and p r e d i c t e d (P) days to 50 percent hatching f o r coho salmon incubated at va r y i n g temperature regimes. Temperature Incubation 50 percent hatching regime , temperature Female D a y g D a y s x SD A P A P F a l l 14°C and down Chehalis Lake 9.3 3.09 1 52.9 55.0 3.97 4.01 2 52.6 55.0 3.96 4.01 E l k Creek 10.0 2.45 1 48.5 52.3 3.88 3.96 Salmon R i v e r 10.8 1.94 1 35.8 36.8 3.58 3.61 2 36.7 36.8 3.60 3.61 Spring 5°C and up i Chehalis Lake 9.3 2.84 1 42.9 55.0 3.76 4.01 2 43.2 55.0 3.77 4.01 E l k Creek 9.3 2.52 1 49.9 57.1 3.91 4.04 Salmon R i v e r 9.3 2.66 1 46.9 46.7 3.85 3.84 2 45.3 46.6 3.81 3.84 122 Table 39. A c t u a l (A) and p r e d i c t e d (P) days to 50 percent emergence f o r coho salmon incubated at v a r y i n g temperature regimes. Temperature Incubation 50 percent emergence regime temperature Female D a y s D a y s x SD A P A P F a l l 14°C and down Chehalis Lake 7.6 3.17 1 99.1 114.8 4.60 4.74 2 98.9 114.8 4.60 4.74 E l k Creek 7.8 3.07 1 95.2 10.15. 4.55 4.62 Salmon R i v e r 7.8 3.06 1 94.6 93.6 4.54 4.54 2 95.0 93.6 4.54 4.54 Spring 5°C and up Chehalis Lake 10.1 3.02 1 78.7 86.7 4.36 4.47 2 78.5 86.7 4.36 4.47 E l k Creek 10.0 2.85 1 68.2 73.7 4.22 4.30 Salmon R i v e r 10.5 3.07 1 65.9 65.6 4.18 4.18 2 66.2 65.6 4.19 4.18 123 r e g r e s s i o n equation f o r each coho pop u l a t i o n (Table 13). The r e s u l t s f o r v each female w i t h i n a popu l a t i o n are s i m i l a r , and a s i m i l a r p a t t e r n emerges fo r p r e d i c t e d emergence and p r e d i c t e d hatching. Again, the p r e d i c t e d emergence times f o r Chehalis Lake and E l k Creek coho are c o n s i s t e n t l y higher than the a c t u a l r e s u l t s . Under the f a l l regime the d i f f e r e n c e between the a c t u a l and p r e d i c t e d emergence time f o r Chehalis Lake i s 16 days, and f o r El k Creek the d i f f e r e n c e i s seven days. The d i f f e r e n c e between the a c t u a l and p r e d i c t e d emergence time under the s p r i n g regime decreases f o r Chehalis Lake coho to nine days and f o r E l k Creek coho to s i x days. In c o n t r a s t , the a c t u a l and p r e d i c t e d r e s u l t s f o r Salmon River coho incubated under both regimes are s i m i l a r , and only d i f f e r by about one day. This same r e s u l t was obtained f o r time to hatching i n Salmon River coho. Figure 10 shows that the emergence data f o r Chehalis Lake and E l k Creek have more curvature than the Salmon R i v e r data. This curvature means that the emergence equations w i l l overestime at intermediate temperatures. Temperature and S i z e : The mean lengths and weights of coho a l e v i n s incubated under the va r y i n g temperature regimes are presented i n Table 40. A comparison of means ( t - t e s t ) i n d i c a t e s that mean a l e v i n length i s a f f e c t e d by the v a r y i n g temperature regimes. For each female the f a l l regime produces longer a l e v i n s than the sp r i n g regime. However, mean weight of a l e v i n s f o r each female i s s i m i l a r under both regimes. W i t h i n e i t h e r regime the d i f f e r e n c e s among females i n mean length and weight of a l e v i n s are s i m i l a r to the r e s u l t s f o r constant i n c u b a t i o n temperatures. The l a r g e s t a l e v i n s are produced by Salmon °- 1 and the s m a l l e s t by e i t h e r E l k Creek ? 1 or Cheha l i s ? 2. These d i f f e r e n c e s are 124 Table 40. Mean lengths and mean weights of coho salmon a l e v i n s incubated at v a r y i n g temperature regimes. Temperature regime Female Length (mm) n x SD Weight (g) x SD F a l l 14°C and down Chehalis Lake E l k Creek Salmon River 1 2 1 2 9 8 25 10 17.30 16.21 0.838 0.742 16.16 0.478 16.18 0.607 0.17 0.14 0.13 0.19 0.026 0.024 0.031 0.032 Spring 5°C and up Chehalis Lake E l k Creek Salmon R i v e r 1 2 10 15 24 15 15 15.69 14.95 17.60 15.39 0.357 0.742 15.70 0.608 0.342 0.498 0.18 0.14 0.12 0.21 0.18 0.019 0.032 0.030 0.028 0.029 Chehalis Lake 1 2 t-value -5.382 -4.010 DF 11 21 t-prob. 0.000 0.001 E l k Creek 1 -2.903 47 0.006 Salmon R i v e r 1 2 -3.554 23' 0.002 \ 125 r e l a t e d to d i f f e r e n c e s i n egg s i z e among females. The mean lengths and weights of coho f r y reared under both v a r y i n g temperature regimes are presented i n Table 41. A comparison of means ( t - t e s t ) i n d i c a t e s mean f r y length i s a f f e c t e d by the var y i n g temperature regimes i n Chehalis Lake and E l k Creek coho but not i n Salmon R i v e r coho. For Chehalis Lake and E l k Creek coho the f a l l regime produces longer f r y than the s p r i n g regime. The mean weight of f r y f o r each female i s greater under the f a l l regime than under the s p r i n g regime. W i t h i n e i t h e r regime the d i f f e r e n c e s among females i n mean length and weight of f r y at emergence are probably r e l a t e d to d i f f e r e n c e s i n egg s i z e . DISCUSSION Two aspects of salmonid reproduction that are considered fundamentally important to s u r v i v a l are: 1) the timing of f r y emergence, and 2) the s i z e of young at emergence (Bams, 1969). G e n e r a l l y , salmonids are thought to migrate and spawn at the time of year which, under average c o n d i t i o n s , provides an optimal temperature c y c l e f o r egg development, and r e s u l t s i n f r y emergence at a time of favourable growing c o n d i t i o n s (Royal, 1953; K i l l i c k , 1955; Andrew and Geen, 1960; Sheridan, 1962; F o e r s t e r , 1968; Smirnov, 1978). S i z e at emergence i s known to i n f l u e n c e swimming performance (Bams, 1967), v u l n e r a b i l i t y to predators (Mead and Woodall, 1968) and growth (Fowler, 1972). The time of f r y emergence i s c o n t r o l l e d by a number of f a c t o r s of which a d u l t behaviour and in c u b a t i o n temperature are probably the two most important. Adult behaviour i n f l u e n c e s f r y emergence i n two ways: 1) through the time of egg d e p o s i t i o n , and 2) through the choice of nest s i t e . Among P a c i f i c salmon 126 Table 41. Mean lengths and mean weights of coho salmon f r y incubated at v a r y i n g temperature regimes. Temperature regime Female Length (mm) x SD Weight (g) x SD F a l l 14°C and down Chehalis Lake E l k Creek Salmon River 1 2 26 24 25 10 27.70 26.16 0.941 0.870 24.73 0.392 28.22 0.909 0.30 0.28 0.21 0.37 0.030 0.031 0.027 0.031 Spring 5°C and up Chehalis Lake 1 19 26. ,18 0. 955 0. ,27 0. 027 2 18 24. ,76 0. ,896 0. ,24 0. ,025 E l k Creek 1 16 22. .30 0. ,955 0, .18 0, .029 Salmon R i v e r 1 15 27, .07 0. .556 0. .33 0. .028 2 15 27 .55 0. ,368 0, .34 0. .029 t-value DF t-prob. Chehalis Lake 1 2 -5.327 43 0.000 -5.102 40 0.000 E l k Creek 1 -9.644 18 0.000 Salmon R i v e r 1 2 -2.205 11 0.048 127 some species t y p i c a l l y spawn e a r l i e r than other species and t h i s i s r e f l e c t e d i n the time of f r y emergence ( i . e . chinook and coho i n the Qualicum system, L i s t e r and Genoe, 1970). In a d d i t i o n to spawning at a s p e c i f i c time, females of two species (sockeye and pink salmon) are known to choose spawning \ s i t e s at l e a s t p a r t l y on the b a s i s of water temperature. In Alaska and A s i a sockeye populations tend to spawn i n areas where upwelling groundwater i s 8° to 12°C l e s s than r i v e r temperature (Olsen, 1968). In c o n t r a s t , pink salmon avoid spawning i n groundwater areas (Krokhin, 1960) . Temperature and S u r v i v a l : Water temperature d i r e c t l y i n f l u e n c e s r a t e of embryonic development, and i n general, warmer i n c u b a t i o n temperatures r e s u l t i n e a r l i e r hatching and emergence. Although increased water temperatures a c c e l e r a t e development, they can a l s o increase zygote m o r t a l i t y . Apparently most salmonid eggs are adapted to a l i m i t e d temperature range, and temperatures above or below t h i s range r e s u l t i n abnormal development or death. Embody (1934) i n d i c a t e d that rainbow t r o u t eggs incubated below 6°C s u f f e r e d high m o r t a l i t i e s . He concluded that temperatures between 9° and 16°C were w i t h i n the normal development range f o r rainbow t r o u t . Since 1934 s e v e r a l authors ( M a r t i n , 1949; Timoshima, 1972) have i n v e s t i g a t e d the i n f l u e n c e of i n c u b a t i o n temperatures on the s u r v i v a l of rainbow t r o u t eggs. B a s i c a l l y , t h e i r r e s u l t s (and mine) confirm Embody's o r i g i n a l data. The normal range f o r development appears to be between 5° and 15°C, but apparently populations can have s l i g h t l y higher or lower ranges. In a d d i t i o n , I observed s l i g h t l y d i f f e r e n t s u r v i v a l r a t e s f o r Tunkwa Lake rainbow t r o u t eggs incubated i n d i f f e r e n t years. There was no s u r v i v a l 128 at 2°C i n 1976 and 1977. In 1976 f r y s u r v i v a l ranged from 60 to 70 percent at 5°, 8° and 11°C and decreased to 52 percent at 14°C. Fry s u r v i v a l at 8° and 11°C was higher (79-100 percent) i n 1977 than i n 1976. At 5°C, i n 1977, there was high f r y s u r v i v a l (80 percent) f o r small eggs, but no f r y s u r v i v a l f o r medium and l a r g e eggs. In 1977 there i s a l s o an i n d i c a t i o n of d i f f e r e n t i a l m o r t a l i t y r e l a t e d to egg s i z e . At 8° and 11°C small eggs survived b e t t e r than both medium and l a r g e eggs. Data on egg s u r v i v a l at d i f f e r e n t i n c u b a t i o n temperatures are not a v a i l a b l e f o r a l l species of Oncorhynchus. Coho appear to be the most c o l d adapted species. A l l e n (1957) and Smirnov (1975) note that i n t h i s species i n c u b a t i o n temperatures above 12°C reduce egg s u r v i v a l . Again, my data are c o n s i s t e n t w i t h the previous r e p o r t s . I observed high s u r v i v a l (75-100 percent) f o r autumn (Salmon River) and winter (Chehalis Lake) spawning coho eggs incubated at constant temperatures from 2°C through 11°C, and l i t t l e (3-5 percent) or no s u r v i v a l at 14°C. An even lower s u r v i v a l r a t e to emergence (32 percent) was observed f o r a s p r i n g spawning coho p o p u l a t i o n ( E l k Creek) incubated at 2°C. S u r v i v a l increased (65-75 percent) at 5°, 8° and 11°C, but again there was no s u r v i v a l a t 14°C. Seymour (1956) and Combs and Burrows (1957) incubated chinook salmon eggs at constant temperatures ranging from 1.1° to 18.1°C. No eggs survived at the lowest (1.1° and 1.7°C) and highest (18.1°C) temperatures. I obtained s i m i l a r r e s u l t s w i t h Babine R i v e r chinook eggs. At 5°, 8° and 11°C there was high a l e v i n and f r y s u r v i v a l (85-90 p e r c e n t ) , w h i l e at 14°C s u r v i v a l was reduced (35 percent) and at 2°C zygote m o r t a l i t y was high (96 p e r c e n t ) . Pink salmon appear to be p a r t i c u l a r l y s e n s i t i v e to i n c u b a t i o n tempera-t u r e s , and i n i t i a l spawning temperature may be important to the o v e r a l l 129 s u r v i v a l of d i f f e r e n t year c l a s s e s of pink salmon. Skud (1958) r e p o r t s that i n Sashin Creek, A l a s k a , even-year runs of pink salmon spawn l a t e r and at lower temperatures than odd-year runs, and that there i s a long term trend *for increased s u r v i v a l f o r the odd-year runs. Spawning normally occurs i n Sashin Creek from August to October. At t h i s time the water temperatures range from 8° to 15°C. The temperature of Sashin Creek u s u a l l y drops below 8°C before mid-October, but sometimes i t reaches t h i s temperature as e a r l y as mid-September (McNeil, 1969). M e r r i l l (1962) suggests that water temperatures might be a c o n t r i b u t i n g f a c t o r to the d i f f e r e n t i a l s u r v i v a l of year c l a s s e s . When the eggs of even-year runs are deposited l a t e r i n the season and at lower temperatures, they may not reach the appropriate stage of development before the onset of c o l d weather. My pink salmon data show high s u r v i v a l (85-97 percent) at 5°, 8° and 11°C, and lower s u r v i v a l (20 percent) at 14°C. There was no s u r v i v a l at 2°C. The egg m o r t a l i t y at 2°C occurred at b l astopore c l o s u r e . This may be the s e n s i t i v e stage suggested by M e r r i l l . Andrew and Geen (1960) measured the s u r v i v a l r a t e s of anadromous Fraser R i v e r sockeye eggs s t a r t e d at i n c u b a t i o n temperatures of 7.2°, 10.0°, 12.8° and 15.6 ° C i Eggs s t a r t e d at 7.2°C s u f f e r e d higher m o r t a l i t i e s than eggs s t a r t e d at 10.0°, 12.8° and 15.6°C. Exposure to temperatures of 16.7° and 18.3°C caused extensive egg death both during and a f t e r exposure. My data (from Weaver Creek sockeye incubated at constant temperatures) i n d i c a t e highest s u r v i v a l (86 percent) at 8°C, reduced s u r v i v a l (38-40 percent) at 2° and 5 C, and low s u r v i v a l (9-10 percent ) at 11 and 14 C. There are no s u r v i v a l data a v a i l a b l e i n the l i t e r a t u r e f o r chum salmon eggs incubated under c o n t r o l l e d temperature c o n d i t i o n s . I observed that Weaver Creek chum s u r v i v a l from egg to f r y was highest (67 percent) at 8°C, 130 decreased to 50-60 percent at 5°, 11° and 14°C, and reached zero (no s u r v i v a l ) at 2°C. This p a t t e r n of s u r v i v a l i s s i m i l a r to the patterns observed f o r pink and chinook salmon; however, chum had lower s u r v i v a l at 5°, 8° and 11°C than e i t h e r pink or chinook, and higher s u r v i v a l a t 14°C. These r e s u l t s i n d i c a t e that chum salmon r e q u i r e i n i t i a l i n c u b a t i o n temperatures above 2°C and that 14°C i s not the upper l i m i t f o r normal development. In general, the range of temperatures (2° to 14°C) I used appear to bracket the optimal i n c u b a t i o n temperatures f o r a l l s i x species. Except f o r coho, 2°C i s c l e a r l y e i t h e r a t , or c l o s e t o , the lower l i m i t of normal development. At the other end of the temperature range, 14°C i s a t , or near, the upper l i m i t of normal development, except f o r chum salmon and, perhaps, rainbow t r o u t . My data suggest that the eggs of coho are the most c o l d adapted of the s i x species and the eggs of chum the most warm adapted. Sockeye have the narrowest temperature range. These observations are c o n s i s t e n t w i t h what i s known about the spawning ecology of these species. For example, coho u s u a l l y spawn l a t e r (and at lower temperatures) than do other species. In c o n t r a s t , sockeye tend to spawn i n areas w i t h upwelling groundwater. Such areas tend to have an almost constant temperature regime. Although death occurred at a l l stages i n development, there were three periods of peak m o r t a l i t y : 1) at b l a s t o d i s c c l o s u r e ( e p i b o l y ) ; 2) at eye pigmentation; and 3) at hatching. The p a t t e r n of m o r t a l i t i e s d i f f e r e d between s p e c i e s , and again suggests s p e c i f i c temperature adaptations. Coho and sockeye, both r e l a t i v e l y c o l d adapted s p e c i e s , s u f f e r low to moderate m o r t a l i t i e s at e p i b o l y i f t h e i r eggs are incubated at low temperatures (<5°C). In c o n t r a s t , pink, chum and chinook salmon and rainbow t r o u t incubated at the same temperature s u f f e r almost t o t a l m o r t a l i t y at e p i b o l y . 131 The d u r a t i o n of e p i b o l y i n salmonids i s apparently a f f e c t e d by d i f f e r -ences i n the r a t i o of y o l k to cytoplasm i n the egg ( B a t t l e , 1944; Knight, 1969; Smirnov et a l . , 1967; Smirnov, 1975). The y o l k sac i n sockeye i s covered by blastoderm e a r l i e r than i n any other s p e c i e s , as a r u l e at the 23-26 somite stage. In coho t h i s process i s a l s o completed r a p i d l y (at 29-30 somites). In c o n t r a s t , rainbow t r o u t eggs complete ep i b o l y by 40 somites, and the l a r g e eggs of chinook, chum and masou do not complete e p i b o l y u n t i l a f t e r the formation of 52-58 somites. In pink salmon epi b o l y i s delayed to the formation of 63-64 somites. The general trend i n salmonids apparently i s f o r c o l d adapted species to complete ep i b o l y e a r l i e r i n development than other species. The second p e r i o d of increased m o r t a l i t y i s at the eye pigmentation stage. Eye pigmentation i s the marker f o r the change from organogenesis to growth (Peterson et a l . , 1977). M o r t a l i t i e s at t h i s stage of development probably i n d i c a t e d i f f i c u l t i e s i n growth metabolism. There was no c l e a r species p a t t e r n i n my data f o r m o r t a l i t i e s at eye pigmentation. The t h i r d p eriod of peak m o r t a l i t y s t a r t s l a t e i n the i n c u b a t i o n period and reaches a peak at or about the time of hatching. M o r t a l i t i e s at hatching f a l l i n t o three c a t e g o r i e s : 1) w e l l developed dead embryos that show no s i g n of hatching; 2) embryos that d i e during hatching; and 3) a l e v i n s that d i e s h o r t l y a f t e r hatching. Hatching m o r t a l i t y i s most n o t i c e a b l e at high i n c u b a t i o n temperatures (11° and 14°C), and i s p a r t i c u l a r l y severe i n c o l d adapted species (coho and sockeye). 132 Temperature and Development Rate: There are only a few published r e p o r t s on the d u r a t i o n of egg develop-ment and emergence time a v a i l a b l e f o r comparison w i t h my data, and d i r e c t comparisons are p o s s i b l e only when temperature was c o n t r o l l e d . U n f o r t u n a t e l y , most of the l i t e r a t u r e data on egg development are from hatchery records and these u s u a l l y are reported as degree-days. This means only the t o t a l i n c u b a t i o n time and mean development temperature can be used f o r comparison. I t i s known, however, that wide v a r i a t i o n s i n length of i n c u b a t i o n period occur even w i t h i n a s i n g l e hatchery (Belding et a l . , 1932; F o e r s t e r , 1968). Presumably, t h i s i s p a r t l y because of d i f f e r e n t temperature c o n d i t i o n s and d i f f e r e n t methods of r e c o r d i n g data. The r a t e of egg development ( i n d i c a t e d by the slope of the r e g r e s s i o n l i n e ) f o r Tunkwa Lake rainbow t r o u t i s higher than reported f o r other rainbow populations (Table 42). One p o s s i b l e e x p l a n a t i o n i s that my eggs were incubated at high oxygen l e v e l s (approaching s a t u r a t i o n ) . High oxygen l e v e l s are known to a c c e l e r a t e development; however, Garside (1966) a l s o incubated rainbow eggs at high oxygen l e v e l s and h i s development slope i s the lowest known f o r rainbow t r o u t . Since Garside used d i f f e r e n t populations i n d i f f e r e n t years, h i s r e s u l t s may be confounded; however, K a w a j i r i (1927), Embody (1934), Bardach et a l . (1972) and Timoshima (1972) a l l obtained s i m i l a r r e s u l t s even though t h e i r experiments were separated by many years and i n v o l v e d many popu l a t i o n s . This suggests there probably are no s t r i k i n g development r a t e d i f f e r e n c e s between most rainbow t r o u t populations. An o v e r a l l r e g r e s s i o n equation was c a l c u l a t e d using the data i n Table 42 plus a d d i t i o n a l l i t e r a t u r e data ( M a r t i n , 1949; Shapavalov and T a f t , 1954; 133 Table 42. L i t e r a t u r e data and r e g r e s s i o n equations f o r the r a t e of egg development f o r rainbow t r o u t . Source Incubation temperature (°C) Days to hatching K a w a j i r i 1927 l n D = 4.921-0.138 T r -0.993 11.3 10.4 9.3 8.7 7.7 6.5 4.5 30.0 32.1 35.0 40.3 46.5 57.5 72.9 Embody 1934 l n D = 4.921-0.136 T r -0.983 16.0 15.0 14.0 13.0 12.0 11.0 10.0 9.0 8.0 7 6 5 4 3.5 18.4 19.3 21.2 23.3 25.6 28.2 30.8 34.7 41.7 50.0 60.0 72.0 86.3 103.5 M a r t i n 1949 15.6 11.7 7.8 21.0 30.0 49.0 Shapovalow and 1954 Taft 15.6 4.4 19.0 80.0 Knight 1963 12.2 23.0 134 Table 42 (cont.) Source Incubation temperature (°C) Days to hatching Garside 1966 In D = 4.761-0.113 T r"-0.982 17.5 15.0 12.5 10.0 7.5 5.0 2.5 18.0 22.0 27.0 33.0 44.0 64.0 106.0 Bardach et a l , 1972 l n D = 4.851-0.130 T r -0.997 15.7 12.0 10.0 7.3 4.5 19.0 24.0 31.0 48.0 80.0 Timoshima 1972 In D = 4.846-0.132 T r -0.990 13.0 10.0 7.0 5.0 2.0 25.0 30.0 50.0 65.0 102.0 135 W i t h l e r , pers. comm.) This o v e r a l l r e g r e s s i o n equation i s l n D = 4.852 -0.132 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.983, and there i s no s i g n i f i c a n t curvature. The o v e r a l l r e g r e s s i o n i n c l u d e s many populations incubated under a v a r i e t y of c o n d i t i o n s and covers the e n t i r e normal range of development temperatures f o r rainbow t r o u t . I t i s probably the best a v a i l a b l e p r e d i c t o r of rainbow t r o u t development r a t e s . Of a l l salmonids rainbow t r o u t are the most s t u d i e d ; however, even f o r t h i s species there i s almost no l i t e r a t u r e on the r a t e of development from hatching to emergence. In my study the r a t e of development between hatching and emergence was the same as the r a t e before hatching ( i . e . the slopes of the r e g r e s s i o n l i n e s were the same). In 1977 a l e v i n s from the three d i f f e r e n t s i z e s of t r o u t eggs hatched, and the f r y emerged, at the same time. Apparently, i n rainbow t r o u t , egg s i z e does not a f f e c t development r a t e . This same r e s u l t i s reported f o r A t l a n t i c salmon, Salmo salar Linnaeus 1758 ( P r i v o l ' n e v , 1960; P r i v o l ' n e v et a l . , 1964). There are s e v e r a l r e p o r t s on the r a t e of development of coho salmon eggs incubated i n h a t c h e r i e s (Table 43). In a l l cases development occurred during d e c l i n i n g temperatures and the r a t e of development was reported i n degree-days. Using these data I c a l c u l a t e d an o v e r a l l r e g r e s s i o n equation f o r coho salmon development. The equation i s l n D = 5.147 - 0.139 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.904 and there i s s i g n i f i c a n t curvature. Because of the way i t was d e r i v e d , t h i s l i t e r a t u r e - b a s e d r e g r e s s i o n cannot be compared d i r e c t l y to my data; however, the slope i s w i t h i n the range of slopes I obtained f o r Chehalis Lake, E l k Creek and Salmon River coho. This suggests that my data do provide reasonable estimates of the e f f e c t s of temperature on development r a t e i n coho salmon. In t h i s s p e c i e s , however, 136 Table 43. L i t e r a t u r e data f o r the r a t e of egg development i n coho salmon. Incubation Source temperature Days to (°C) hatching Shapovalov and B e r r i a n 1940 8.9 48.0 Shaw and Magh 1943 10.7 37.0 Gribanov 1948 4.5 93.0 Iev l e v a ' 1951 2.9 136.0 Semko 1954 2.2 147.5 Shapovalov and Taft 1954 10.7 38.0 8.9 48.0 A l l e n 1957 11.4 41.5 8.2 46.0 Smirnov 1960 9.0 47.0 8.9 52.0 4.1 103.0 Smirnov 1975 6.1 40.0 5.0 54.0 1.6 130.0 1.2 147.0 W i t h l e r pers. comm. 7.0 79.6 7.0 78.2 7.0 80.4 7.0 78.0 4.0 100.7 4.0 101.0 4.0 101.6 137 there are i n t e r p o p u l a t i o n d i f f e r e n c e s i n development r a t e s . My data ( F i g . 9, Tables 10 and 11) c l e a r l y i n d i c a t e c o n s i s t e n t d i f f e r e n c e s between the three i n v e s t i g a t e d p opulations. This observation means that estimates derived from one p o p u l a t i o n w i l l not n e c e s s a r i l y f i t some other p o p u l a t i o n . There are no comparable data a v a i l a b l e f o r post-hatching development r a t e s i n coho, but again my data suggest development from hatching to emergence proceeds at the same r a t e as pre-hatching development. For chinook salmon there i s a rep o r t (Smirnov, 1975) on the e f f e c t of temperature on development r a t e (to mass ha t c h i n g ) . I supplemented Smirnov's data w i t h two other l i t e r a t u r e r e p o r t s (McKee, 1950; Gangmark and Bakkala, 1960) and c a l c u l a t e d a r e g r e s s i o n equation f o r chinook salmon development r a t e s . The equation i s l n D = 5.348 - 0.127 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.974, and there i s s i g n i f i c a n t curvature. The slope of t h i s l i n e i s lower than my slope f o r Babine R i v e r chinook. This probably i n d i c a t e s that there are i n t e r p o p u l a t i o n d i f f e r e n c e s w i t h i n t h i s species. Once again the slopes of the pre- and post-hatching development curves f o r chinook are the same. This i n d i c a t e s that development from hatching to emergence i s i n f l u e n c e d by temperature i n the same way as e a r l i e r develop-mental processes. Smirnov (1975) a l s o i n v e s t i g a t e d the i n f l u e n c e of temperature on the development r a t e of pink salmon i n Kamchatka. His data are presented i n Table 44. When Smirnov's data are compared w i t h my C h i l l i w a c k R i v e r pink salmon data (Table 20) they are almost i d e n t i c a l . This suggests temperature-development r a t e s i n pink salmon may not d i f f e r over the species range. The r e g r e s s i o n l i n e obtained by combining my data w i t h Smirnov's i s l n D = 4.900 - 0.080 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.990, and there i s 138 Table 44. L i t e r a t u r e data f o r the r a t e of egg development i n pink salmon. Incubation Days to Source temperature hatching ( ° C ) Smirnov 1975 8.2 50.0 5.4 55.0 4.9 59.0 4.0 70.0 3.7 75.0 3.1 80.0 2.9 84.0 2.4 88.0 2.0 92.0 1.6 104.0 1.1 150.0 c 139 s i g n i f i c a n t curvature. An important p o i n t to note i s that pink salmon have the slowest r a t e of development recorded f o r any t r o u t or salmon (Table 45). Again, l i t e r a t u r e data on development r a t e s from hatching to emergence are not a v a i l a b l e . My data (Table 21) f o r post-hatching development r a t e s i n pink salmon are unique and suggest that development from hatching to emergence proceeds at the same r a t e as pre-hatching development. S e v e r a l s t u d i e s ( I e v l e v a , 1951; Smirnov, 1958, 1959 , 1975; Simon, 1963; W i t h l e r and Morley, 1970) c o n t a i n data on in c u b a t i o n time i n sockeye salmon. Apparently, sockeye have the longest i n c u b a t i o n p e r i o d of any Oncorhynchus. I c a l c u l a t e d a temperature-development r a t e r e g r e s s i o n l i n e based on l i t e r a t u r e records (Table 46). The equation f o r t h i s l i n e i s l n D = 5.249 -0.104 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.916, and there i s no s i g n i f i c a n t curvature. The slope of t h i s l i t e r a t u r e - b a s e d l i n e i s lower than the slope derived from Weaver Creek sockeye. This may i n d i c a t e i n t e r p o p u l a t i o n d i f f e r e n c e s i n temperature-development r a t e s i n sockeye. This suggestion i s strengthened by F o e r s t e r ' s (1968) observations on nine sockeye h a t c h e r i e s i n B. C. He noted l i t t l e v a r i a t i o n i n i n c u b a t i o n time w i t h i n h a t c h e r i e s but wide v a r i a t i o n between h a t c h e r i e s . U n f o r t u n a t e l y , t h i s between-hatchery v a r i a t i o n i s l i k e l y due to a combination of genetic ( i n t e r p o p u l a t i o n ) and environmental (temperature) f a c t o r s . U n l i k e the other P a c i f i c salmon there are some data a v a i l a b l e on emergence times f o r sockeye salmon. Mead and Woodall (1968) compared sockeye salmon f r y produced by h a t c h e r i e s , a r t i f i c i a l channels and n a t u r a l spawning areas i n three Fraser R i v e r t r i b u t a r i e s . At a mean in c u b a t i o n temperature of 4.9°C, Upper P i t t R i v e r sockeye emerged from the hatchery i n 221.0 days, from the a r t i f i c i a l channel i n 224.0 days and from the n a t u r a l 140 Table 45. Rates of development to 50 percent hatching and emergence, presented i n t h i s study. Species Rate of development to 50 percent hatching Rate of development to 50 percent emergence Pink salmon Chum salmon Coho salmon Chehalis Lake E l k Creek Salmon R i v e r Sockeye salmon Chinook salmon Rainbow t r o u t l n D = 4.917 - 0.082 T l n D = 5.104 - 0.105 T l n D l n D l n D l n D l n D l n D 5.278 5.194 5.325 5.463 5.417 4.860 0.137 T 0.124 T 0..159 T 0.127 T 0.136 T 0.143 T l n E = 5.321 - 0.059 T l n E = 5.603 - 0.097 T l n E l n E Ln E l n E l n E l n E 5.594 5.789 5.567 5.775 5.945 5.292 0.112 T 0.149 T 0.109 T 0.113 T 0.135 T 0.140 T 141 Table 46. L i t e r a t u r e data f o r the r a t e of egg development i n sockeye salmon. Incubation Days to Source temperature hatching ( ° C ) Smirnov • 1959 1.7 174.0 Foerster 1968 11.0 50.0 10.6 57.0. 10.3 59.0 9.7 74.0 8.2 90.0 7.3 98.0 5.0 116.0 4.8 110.0 4.3 106.0 4.1 141.0 3.8 171.0 3.5 110.0 3.2 133.0 3.2 123.0 2.9 132.0 2.2 156.0 F a l l i s 1970 15.0 48.0 4.0 140.0 Hanamura 1966 3.1 150.0 Smirnov 1975 10.7 58.0 8.1 71.0 4.2 142.0 3.1 173.0 142 spawning area i n 233.0 days. At a mean in c u b a t i o n temperature of 5.8"C, Weaver Creek sockeye emerged- from the hatchery i n 169.0 days, from the a r t i f i c i a l channel i n 173.0 days and from the n a t u r a l spawning area i n 178.0 days. Cultus Lake sockeye incubated at 8.1°C emerged from the hatchery i n 128.0 days, from the a r t i f i c i a l spawning area i n 143.0 days and from" the n a t u r a l spawning area i n 154.0 days. My emergence data on Weaver Creek sockeye are s i m i l a r to Mead and Woodall's hatchery data. In a d d i t i o n , my data i n d i c a t e post-hatching development i n sockeye salmon i s i n f l u e n c e d by temperature i n the same way as pre-hatching development. To compare my temperature-development data f o r chum salmon w i t h other data I c a l c u l a t e d a l i t e r a t u r e - b a s e d temperature-development r e l a t i o n s h i p from the data l i s t e d i n Table 47. This c a l c u l a t e d r e g r e s s i o n equation i s l n D = 5.1804 - 0.119 T; the c o r r e l a t i o n c o e f f i c i e n t i s -0.980, and there i s no s i g n i f i c a n t curvature. This equation i s s i m i l a r to the equation I derived f o r Weaver Creek chum salmon. The l i n e a r r e l a t i o n s h i p f o r the r a t e of development to hatching i n chum salmon i s s i m i l a r to the r e s u l t s presented f o r brown t r o u t and l a k e t r o u t by Embody (1934). Once again the slopes of the pre- and post-hatching development r e g r e s -sions are the same f o r chum salmon. This i n d i c a t e s that development from hatching to emergence i s i n f l u e n c e d by temperature i n the same way as e a r l i e r developmental processes. I t appears that a l l salmonids respond to increases i n temperature by i n c r e a s i n g t h e i r development r a t e ; however, the magnitude of t h i s response d i f f e r e s between sp e c i e s . Although the r e l a t i o n s h i p i s not p r e c i s e , my data suggest c o l d adapted species ( i . e . species w i t h high s u r v i v a l at low tempera-143 Table 47. L i t e r a t u r e data for the rate of egg development i n chum salmon. Incubation Days to Source % temperature hatching (°C) D i s l e r 1953 2.7 124.0 Soin 1954 13.0 30.0 Kubo et a l . 1955 8.0 61.5 Alderdice et a l . 1958 9.8 52.1 9.9 52.0 9.8 57.5 9.7 60.8 Withler and Morley 1970 11.1 50.2 11.1 48.4 11.1 48.6 11.1 47.6 Wild 1973 12.8 41.6 10.0 52.3 7.2 71.3 Smirnov 1975 10.0 51.0 8.8 58.0 West 1976 5.0 104.0 5.0 105.1 5.0 108.7 5.0 106.4 Withler pers. comm. 4.0 103.8 4.0 105.7 4.0 104.3 144 tures) tend to increase t h e i r r a t e of development at high temperatures more r a p i d l y than warm adapted s p e c i e s . This suggests the developmental processes i n such cold-water species are l e s s homeostatic than i n species adapted to spawn at higher temperatures. Temperature and S i z e : There are s u r p r i s i n g l y few data a v a i l a b l e on s i z e at hatching and emergence i n e i t h e r Salmo or Oncorhynchus. What data there are are incomplete and derived from populations s c a t t e r e d over a wide geographic range. In a d d i t i o n , the developmental temperature regime i s u s u a l l y given as a mean temperature, and egg s i z e (an important c o n t r i b u t o r to a l e v i n and f r y s i z e ) i s r a r e l y mentioned. These f a c t o r s make i t d i f f i c u l t to assess my data, but i n a l l cases they are w i t h i n the s i z e ranges given i n the l i t e r a t u r e . Timoshima (1972), working on the embryonic development of rainbow t r o u t at d i f f e r e n t temperatures (2°, 5°, 7°, 10° and 13°C), found that a l e v i n s hatched at high and low temperatures weighed l e s s than those hatched at 5° and 7°C. My data on rainbow t r o u t are d i f f i c u l t to compare w i t h Timoshima's data, because I d i v i d e d my eggs i n t o three s i z e c l a s s e s (Tables 7 and 8 ) . I found no e f f e c t of temperature on a l e v i n s i z e (both length and weight) i n small eggs, but a pronounced e f f e c t i n medium and l a r g e eggs. The r e s u l t s f o r f r y ( s i z e a t emergence) are l e s s c l e a r but s i m i l a r i n p a t t e r n . There are few l i t e r a t u r e records of coho s i z e at hatching ( I e v l e v a , 1951; Smirnov, 1975). Since my data i n c l u d e eggs from d i f f e r e n t p o p u l a t i o n s , and from d i f f e r e n t females w i t h i n p o p u l a t i o n s , the r e s u l t s are not simple (Tables 14 and 15). In two populations (Chehalis Lake and Salmon Ri v e r ) a l e v i n length increases as i n c u b a t i o n temperature decreases. This inverse 145 r e l a t i o n s h i p between a l e v i n length and i n c u b a t i o n temperature i s a l s o known i n A t l a n t i c salmon (Petersen et a l . , 1977). In the E l k Creek p o p u l a t i o n s , however, the longest a l e v i n s are produced at 8°C and the sh o r t e s t at 2°C. This observation i s con t r a r y to the trend f o r Chehalis Lake and Salmon River coho. Since E l k Creek coho spawn i n the s p r i n g , and the other two populations spawn i n the autumn and e a r l y w i n t e r , t h i s d i f f e r e n c e may be adaptive. My data a l s o i n d i c a t e i n c u b a t i o n temperature i n f l u e n c e s coho f r y s i z e ( s i z e at emergence). In general (Table 15) f r y weight and len g t h i s greatest at intermediate i n c u b a t i o n temperatures and lowest at the extremes (2° and 14°C) . In chinook, pink, sockeye and chum salmon, in c u b a t i o n temperatures a l s o i n f l u e n c e a l e v i n and f r y s i z e . The general trend i s f o r s i z e to increase as temperature decreases. The one exception i s the chum salmon. In t h i s s p ecies, a l e v i n length decreases as temperature decreases (Table 30); however, at emergence the more common r e l a t i o n s h i p ( l a r g e r f r y at lower temperatures) i s observed. Bams (1969) attempted to e x p l a i n the general trend f o r s i z e to decrease as development temperature increases on the ba s i s of y o l k absorption r a t e s . He argues that the r a t e of y o l k absorption i s a f u n c t i o n of temperature and the q u a n t i t y of a v a i l a b l e y o l k . The r a t e of d i f f e r e n t i a t i o n i s a l s o determined by temperature. When an increased metabolic demand occurs, the r a t e of y o l k absorption does not in c r e a s e . Therefore, the r a t e of y o l k absorption i s independent of v a r i a t i o n s i n metabolic demand, an adequate supply of y o l k i s ensured f o r the length of time r e q u i r e d f o r development as determined by the temperature regime, and the predetermined time of emergence i s unaffected. However, w i t h an unchanging supply r a t e , an 146 increased metabolic demand must reduce the part of the a v a i l a b l e y o l k which otherwise would be used f o r growth. E v i d e n t l y , metabolic demand and d i f f e r e n t i a t i o n take precedence over growth, and the r e s u l t of an increase i n metabolic demand i s reduced growth i n mass (Hayes and Armstrong, 1942). Varying Temperature Regimes: These experiments were performed to t e s t the hypothesis that the eggs of f a l l spawning salmonids are adapted to develop during a decreasing temperature regime, w h i l e the eggs of s p r i n g spawning species are adapted to develop during an i n c r e a s i n g temperature regime. Unf o r t u n a t e l y , the r e s u l t s are e q u i v o c a l , and there are no d i r e c t l y comparable l i t e r a t u r e data. There are, however, two accounts ( K a w a j i r i , 1927; Peterson et a l . , 1977) of the e f f e c t s of v a r y i n g temperature regimes on the development of Salmo. K a w a j i r i (1927) incubated rainbow t r o u t eggs at ten constant temperatures (2.8°, 4.6°, 6.5°, 7.7°, 8.7°, 9.3°, 10.4°, 11.3°, 11.7° and 12.9°C). There was no s u r v i v a l at 2.8°, 11.7° and 12.9°C. S u r v i v a l increased as constant i n c u b a t i o n tempera-tures decreased and the highest s u r v i v a l was at 4.5°C. In t h i s experiment, s u r v i v a l was probably a f u n c t i o n of oxygen as w e l l as temperature, s i n c e the eggs were incubated i n standing unaerated water. K a w a j i r i (1927) a l s o incubated rainbow t r o u t eggs i n v a r y i n g temperature regimes. Using the same temperatures as i n the constant temperature experiment he s h i f t e d the eggs on a d a i l y b a s i s . The s h i f t s were made i n the f o l l o w i n g way: 2.8° to 12.9°C, 4.5° to 11.7°C, and so on, so as to change the temperature repeatedly from low to h i g h and v i c e v e r s a . This r e s u l t e d i n f i v e temperature regimes (7.1 ± 5.5°; 7.8 ± 4.0°; 8.7 ± 2.4°; 8.8 ± 1.5°; and 8.8 ± 0.7°C). As the v a r i a t i o n i n temperature increased so d i d m o r t a l i t y , but the time r e q u i r e d 147 J under each regime to achieve 50 percent hatching was s i m i l a r (41.6, 40.2, 39.6, 39.0, 38.5 days r e s p e c t i v e l y ) . Peterson et a l . (1977) reared A t l a n t i c salmon eggs and a l e v i n s under c o n d i t i o n s where the temperature was s y s t e m a t i c a l l y v a r i e d e i t h e r at f e r t i l i z a t i o n , at the eyed egg stage or at hatching. The f e r t i l i z e d A t l a n t i c salmon eggs were d i v i d e d i n t o 66 l o t s , 11 l o t s at each temperature 02.0°, 4.0°, 6.0°, 8.8°, 10.0° and 12.0°C). At the 100 percent eyed egg stage, f i v e l o t s from each of the o r i g i n a l 11 were placed one at each of the other temperatures and the remaining s i x l o t s were he l d at the o r i g i n a l temperature (T^ ) . Temperatures from eyed egg stage to hatching were designated 1^. At 50 percent hatching, the remaining s i x l o t s were t r a n s f e r r e d , one l o t to each temperature. Post-hatching temperatures were designated T^. This complex experimental design produced s i x constant temperatures, 30 decreasing temperatures and 30 i n c r e a s i n g temperatures. The systematic v a r i a t i o n of temperature during egg development demonstrated that temperature from f e r t i l i z a t i o n to eye pigmentation had a s i g n i f i c a n t but l e s s e r e f f e c t on s i z e at hatching than d i d temperatures from eye pigmentation to hatching. This i s understandable s i n c e eye pigmentation i s a morphological marker that corresponds to the completion of organogenesis and the commencement of growth. Comparison of my s u r v i v a l data f o r rainbow t r o u t and coho salmon reared under f a l l and s p r i n g temperature regimes w i t h the data of K a w a j i r i and Peterson et a l . i s d i f f i c u l t . They s h i f t e d eggs or a l e v i n s at s p e c i f i c development stages, whereas both coho and rainbow eggs and a l e v i n s were s h i f t e d g r a d u a l l y . In gene r a l , the i n c r e a s i n g temperature regime f o r rainbow t r o u t produced higher s u r v i v a l than d i d the decreasing regime. This i s c o n s i s t e n t w i t h the hypothesis;.however, there was no c l e a r p a t t e r n of 148 s u r v i v a l f o r coho salmon under e i t h e r regime. These r e s u l t s are p o s s i b l y because 14.0°C i s c l o s e to the upper l e t h a l l i m i t f o r coho. Perhaps, i f the experiment were repeated at a lower upper temperature (say 11°C), the r e s u l t s would be c l e a r e r . SUMMARY Constant i n c u b a t i o n temperatures a f f e c t zygote and a l e v i n s u r v i v a l i n P a c i f i c salmon and rainbow t r o u t . Zygotes and a l e v i n s of "warm" water species have higher s u r v i v a l at 14°C and no s u r v i v a l at 2°C. In c o n t r a s t , the zygotes and a l e v i n s of " c o l d " water species have higher s u r v i v a l at 2°C and no s u r v i v a l at 14°C. The r a t e of development to hatching and emergence i s an inv e r s e r e l a t i o n -ship between temperature and i n c u b a t i o n time. A c u r v i l i n e a r r e l a t i o n s h i p i s present f o r a l l species except f o r chum salmon at hatching and pink salmon at emergence. Low constant i n c u b a t i o n temperatures produce l a r g e r a l e v i n s and f r y than high constant i n c u b a t i o n temperatures. Varying temperature regimes a f f e c t zygote and a l e v i n s u r v i v a l d i f f e r e n t -l y i n coho salmon and rainbow t r o u t . There are no c l e a r d i f f e r e n c e s i n zygote and a l e v i n s u r v i v a l f o r coho salmon w i t h e i t h e r regime. However, the i n c r e a s i n g temperature regime produces higher s u r v i v a l i n rainbow t r o u t zygotes and a l e v i n s than the decreasing temperature regime. The r a t e of development to hatching f o r zygotes incubated at e i t h e r v a r y i n g temperature regime i s s i m i l a r w i t h i n a species because of s i m i l a r mean i n c u b a t i o n temperatures between regimes. But, the r a t e of development 149 to emergence f o r a l e v i n s incubated at e i t h e r regime i s d i f f e r e n t because of the d i f f e r e n t mean i n c u b a t i o n temperatures between regimes. Mean development temperatures to hatching and emergence and the appropriate r e g r e s s i o n equations f o r each species produce p r e d i c t i o n s which are s i m i l a r to the a c t u a l development r a t e s . 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