Effect of Female Size, Egg Size, and Water Temperature on Developmental Biology of Chum Salmon (Oncorhynchus keta) from the Nitinat River, British Columbia

Abstract

We incubated eggs and alevins for five chum salmon (Oncorhynchus keta) families in each of three female size classes under controlled water temperatures of 4, 8, and 12 °C. Egg survival from fertilization to hatching was highest for eggs from small females and lowest for eggs from large females at all three incubation temperatures. Egg survival was highest at 8 °C, and at 4 °C survival rates were largely determined from fertilization to epiboly, but at 12 °C the lowest egg survival rates were recorded from eye pigmentation to hatching. There were marked differences in egg survival rates among families. Overall survival rates from egg fertilization to fry 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. Alevins hatching at 4 °C were the longest, but those hatching at 12 °C were the heaviest. Larger females produced alevins with both more yolk 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.