No abstract

We examined regional and latitudinal variation in fecundity and egg weight for five species of Pacific salmon (Oncorhynchus) along the Pacific coast of North America. Data were examined for 24 chum salmon, 15 pink salmon, 34 sockeye salmon, 44 chinook salmon, and 40 coho salmon populations from published sources, unpublished Canadian hatchery records, our own laboratory investigations, and other unpublished sources. Substantial regional variation in fecundity and egg weight was observed, with salmon on the Queen Charlotte Islands and Vancouver Island in British Columbia generally having lower fecundity and larger egg size than nearby mainland populations. The relative distance of freshwater migration to the spawning grounds generally had a marked effect on both fecundity and egg size, with populations spawning in the upper portions in the drainages of large rivers like the Fraser River in British Columbia having reduced fecundity and egg size compared with coastal spawning populations. Fecundity was generally higher and egg size generally lower in more northern populations of sockeye, chinook, and coho salmon compared with southern ones. We suggest that egg size tends to be lower in northern populations of some species as a result of increased fecundity due to their older ages at maturity and a limited amount of energy that can be expended on egg production.

Previous studies have demonstrated morphological differences between hatchery-reared coho salmon (Oncorhynchus kisutch) of hatchery origin and wild-reared coho of wild origin. We tested for a genetic component to this divergence by comparing coho from hatchery and wild populations both reared in the same hatchery environment and for an environmental component by comparing hatchery- and wild-reared coho both of wild origin. As in the previous studies, wild-reared fish from wild populations had greater head dimensions, larger median fins, and deeper bodies than did hatchery-reared fish from hatchery populations. This difference, summarized by the first principal component (PC1) of the size-adjusted data, was related to rearing environment rather than to genetic differences between hatchery and wild populations. Genetic divergence (or maternal effects) did occur between hatchery and wild populations along PC2 and PC3, but this divergence was slight compared with the environmentally induced differences between the two types of fish along PC1.

Beacharn, %. D., and @. B. Murray. 1985. Effect s f female size, egg size, and water temperature o n developmental biology of chum salmon (Owcsrhyracheas keta) from the Nitinat River, British Columbia.Can. I. Fish. Aquat. Sci. 42: 1755-1765 We incubated eggs and alevins for five churn salmon /Oncoshynchus &eta) families in each of three female size classes under controlled water temperatures of 4, 8, and 12°C. Egg survival from fertilization t o hatching was highest for eggs from small females and lowest for eggs from large females at a$! three incubation temperatures. Egg survival was highest at 8"C, and at4"C survival rates were largely determined from fertilization to epiboly, but at 12°C the lowest egg survival rates were recorded from eye pigmentation t o hatching. There were marked differences i n egg survival rates among families. Overall survival rates from egg fertilization t o F r y emergence were most divergent between the large and small female size class at 12°C. Hatching time of the alevins and emergence time of the fry were similar among the three female size classes at each incubation temperature. AIevins hatching at4"C were the longest, but those hatching at 12°C were the heaviest. Larger females produced alevins with both more yo!k reserves and more body tissue at hatching than those from smaller females. The relation between egg weight and subsequent alevin size was dependent upon incubation temperature. At emergence, the longest and heaviest fry were produced by the largest female size class.Des ~u f s et des alevins v6sicul6s provenant de cinq families de saumon k6ta (Oncorhynchus keta) reparties en trois classes de ionguepr de femelles snt kt6 gardes en incubateur dont la temperature de l'eau etait maintersue A 4, 8 et 12°C. A ces temp6ratures, la survie des eufs, de la fertilisation A If6closion, &tail plus 4Bev6e chez ceux provenant de petites fernelles, et plus faible chez ceux issus de grosses femeltes. La survie $tait plus elev6e B 8°C tandis qu'a 4"C, les taux de suwie etaient en grande partie fixes de la fertilisation B If6pibolie; B 12"C, les plus faibDes taux de survie ont et6 observ6s de la pigmentation des yeux A l'6clssion. !I y avait des diffkrences marqu6es entre les taux de survie des e u f s selon la farnille. Pour ce qui est des petites et des grosses femelles, la variabilite des taux de saarvie globaux de la fertiiisation a 0'6mergence des alevins 6tait plus 6lev6e 2i 12°C. be moment de la sortie des alevins vesicul6s et de If6mergence des aievins nageants 6tait semblable ckes les troisclasses de longueur de femelles a chaque temperature d'incubatisn. kes alevins v6sicul6s gardes A4"C etaient les plus Dongs tandis que ceux qui 6taient maintenus Al2"C etaient Bes plus gros. Par rapport aux petites femelles, Bes grosses femelles ont produit des alevins v6sicul6s possedant de plus importantes rkseaves viteliines et plus de tissu corpsrel a lf6closion. ha relation entre le poids des ~u f s et la taille ult6rieure des alevins vesicul6s d6pendait de la temperature B ['incubation....

1988. Effect of incubation temperature on the development of five species of Pacific salmon (Oncorhynchus) embryos and alevins. Can. J. Zool. 66: 266 -273. Embryo and alevin survival, time to hatching and emergence, and alevin and fry size of five species of Pacific salmon (Oncorhynchus) were observed at five incubation temperatures (2, 5, 8, 11, and 14°C). No pink (Oncorhynchus gorbuscha) or chum (0. keta) salmon embryos survived to hatching at 2°C. Coho ( 0 . kisutch) and sockeye ( 0 . nerka) salmon had higher embryo survival at 2°C than chinook ( 0 . tschawytscha) salmon. At 14"C, chum, pink, and chinook salmon had higher embryo survival than coho or sockeye salmon. In all species, peaks of embryo mortality occurred at specific developmental stages (completion of epiboly, eye pigmentation, and hatching). Alevin survival to emergence was high for all species, except for coho and pink salmon at 14°C. Hatching and emergence time varied inversely with incubation temperature, but coho salmon hatched and emerged sooner at all temperatures than the other species. Coho and sockeye salmon alevins were larger at 2"C, pink, chum, and chinook salmon alevins were larger at 5 and 8°C. Coho salmon fry were larger at 2"C, chinook and chum salmon fry were larger at 5"C, and sockeye and pink salmon fry were larger at 8°C. High incubation temperatures reduced fry size in all species. Each species of Pacific salmon appears to be adapted to different spawning times and temperatures, and thus indirectly to specific incubation temperatures, to ensure maximum survival and size and to maintain emergence at the most favorable time each year. MURRAY, C. B., et MCPHAIL, J. D. 1988. Effect of incubation temperature on the development of five species of Pacific salmon (Oncorhynchus) embryos and alevins. Can. J. Zool. 66 : 266-273.La survie des embryons et des alevins, le temps necessaire l'eclosion et a l'emergence, ainsi que la taille des larves (alevins vesicules) et des alevins ont ete mesurCs chez cinq espkces de saumons du Pacifique (Oncorhynchus) gardCs a cinq tempkra-