Comparative Developmental Biology of Chum Salmon (Oncorhynchus keta) from the Fraser River, British Columbia

Abstract

Eggs and alevins from 32 families of chum salmon (Oncorhynchus keta) from seven Fraser River stocks spawning at different times or in different tributaries were incubated in controlled water temperatures of 4, 8, and 12 °C. There were significant differences in egg and alevin survival among stocks and among families within stocks in the different incubation temperatures. Highest egg survival for a late-spawning Vedder River stock occurred at 4 °C, while egg survival from other stocks was highest at 8 °C. Late-spawning stocks had smaller eggs and earlier times of fry emergence than did early-spawning ones. There was no effect of spawning time on alevin hatching time. Alevins hatching at 8 °C were larger than those hatching at 4 or 12 °C, but there were no stock differences in alevin length or tissue weight. Stocks with greater egg sizes produced alevins of greater total weight. Fry emerging at 8 °C were larger than those emerging at 4 or 12 °C, and fry from early-spawning stocks were longer and had greater tissue weight than those from late-spawning ones. There were significant differences among families within stocks in size of alevins and fry, and family differences should be accounted for in studies of salmonid developmental biology.