Meeting Abstract

63.10  Wednesday, Jan. 6  Using time-series data to partition evolutionary and plastic responses to climate change in Pacific salmon: a case study of the historical shift in run-timing in Columbia River sockeye salmon CROZIER, Lisa G.; NWFSC, NOAA-Fisheries Lisa.Crozier@noaa.gov

Salmon are highly adaptable and behaviorally complex, and they are responding actively to climate change. Sockeye salmon now migrate up the Columbia River almost 11 days earlier than they did in the 1940s. I explored a combination of plastic and evolutionary mechanisms that could explain this shift, and compared alternative models using an information theoretic approach. Based on recent radio-tracking studies of sockeye salmon migration success, I developed a model of thermal stress-induced mortality. Using ~60 years of daily fish counts and river temperatures, I back-calculated cumulative historical selection pressure. I show that there has likely been consistent selection for earlier migration. Both the long-term trend and annual variation in migration timing are consistent with the effects of ongoing evolution and a plastic response to river flow. Although selection improves the ability of salmon to tolerate long-term climate change, it also exacts a demographic cost (i.e., mortality), which could be significant in small populations. Rising river temperatures are certain to continue as the climate warms, and will affect salmon life histories across their geographic range. Understanding both ecological and evolutionary responses will facilitate conservation of these diverse species.