Temperature, Egg Size, and Development of Embryos and Alevins of Five Species of Pacific Salmon: A Comparative Analysis

Abstract

We examined rate of development to alevin hatching and fry emergence, embryo and alevin survival, and alevin and fry size for five Pacific salmon species. There was little difference among values for hatching and emergence time predicted by a modified thermal sums model, power law model (log-inverse Belehrádek), or quadratic model. Coho salmon Oncorhynchus kisutch had the fastest rates of development to hatching and emergence of the five species investigated; rankings for the other species depended upon temperature range. Coho salmon embryos had the highest survival rates at low incubation (1.5°C) temperatures. Embryos of pink salmon O. gorbuscha had the lowest survival at temperatures less than 4°C. For all five species, incubation temperature was the more important factor in determining alevin length, and egg size was the more important factor in determining alevin weight. Egg weight was a major determinant of fry weight at emergence. Rates of development to hatching and emergence, and alevin and fry size, differed by species in response to changes in temperature, Coho salmon alevins and fry were proportionately larger at 4°C than at 8°C or 12°C, but alevins and fry of pink salmon and chum salmon O. keta were largest at 8°C. Variation in development characters of Pacific salmon reflected adaptations to each speciesˈ life history pattern.