Researchers from Oregon State University, the USGS, and the U.S. Forest Service studied coho salmon, from hatching through the first summer of life, in the Copper River Delta, Alaska to evaluate links between phenologies of life stages in a species with a complex life cycle.
They studied streams fed by surface water with high seasonal thermal variability and streams fed by groundwater that exhibit much lower thermal variability. Researchers noted that coho hatching and emergence occurred at the same time among streams even with marked thermal variability, and overall fish sizes among streams were similar. Authors speculate that the synchrony in phenologies, despite different thermal regimes, may occur because of timing of peak food resources and the optimal capacity of coho to grow within the brief window of Alaska summers. Results provide insights into the interactions between environmental variability and the early life-history stages of coho salmon.
Campbell, E.Y., Dunham, J.B., Reeves, G.H., Wondzell, S.M., 2018, Phenology of hatching, emergence, and end-of-season body size in young-of-year Coho salmon in thermally contrasting streams draining the Copper River Delta, Alaska: Canadian Journal of Fisheries and Aquatic Sciences, https://doi.org/10.1139/cjfas-2018-0003.