Population Origin and Water Temperature Affect Development Timing in Embryonic Sockeye Salmon

Abstract

Predicting the future impact of changing thermal regimes on life history stages for wild fish requires a better understanding of the relative importance of population origin and offspring size on embryonic development. We assessed hatch timing and offspring size of Sockeye Salmon Oncorhynchus nerka in relation to egg size (variation from full-sibling families), population origin, and temperature (three treatments of 10, 14, and 16°C). Both hatch timing and hatch duration varied by the interacting effects of population origin and thermal treatment, shown in crossing reaction norms. Hatching was faster, yet more variable, at higher temperatures across many groups, so while fish generally hatched faster, developmental asynchrony also increased among families. On average, fish incubated at 16°C were shorter but not lighter at hatch, showing developmental tradeoffs between basal metabolic requirements and growth. Egg size decreased among populations as migratory distance increased, but development rates were not related to egg size. In this case, embryonic development rates were linked to temperature and population-specific cues for hatch timing more than to the maternal influence of egg size.

Received March 10, 2014; accepted June 3, 2014

ACKNOWLEDGMENTS

All research was conducted with the approval of the Animal Ethics Committee of the University of British Columbia, according to the principles of the Canadian Council on Animal Care (#A08-0388). C.K.W. was supported by a Natural Sciences and Engineering Research Council of Canada, Canada Graduate Scholarship and a VanDusen Graduate Fellowship from the University of British Columbia Faculty of Forestry, with project funding deriving from Natural Sciences and Engineering Research Council of Canada Strategic and Discovery Grants to S.G.H. and support from Fisheries and Oceans Canada's Environmental Watch group. The authors thank members of the Okanagan Nation Alliance, in particular R. Bussanich and S. Folks, for field support and assistance. Many thanks to all the members of the Pacific Salmon Ecology and Conservation Laboratory, especially A. Lotto, J. Burt, E. Vogt, A. Haas, K. Robinson, N. Sopinka, and E. Martins.