Analysis of long-term census data to identify factors affecting survival and life history strategies of coho salmon

Abstract

A major unknown facing salmon (Oncorhynchus spp.) fisheries biologists and managers is how climate change and other factors will affect abundance. This proposed research makes use of >35 years of census data to investigate the factors that influence marine survival and life history strategies of coho (O. kisutch) salmon from Auke Creek, AK. It builds upon findings from our previously funded NPRB project which has revealed dramatic shifts in Auke Creek juvenile and adult salmon run timing over the previous three decades. Because early marine survival is such an important life history stage, an outstanding question is whether shifts in run timing of Auke Creek salmon will lead to mismatches between their migrations and optimal environmental conditions (the “mismatch hypothesis”). In 2016, we recorded the earliest (tied) and lowest run ever of Auke Creek adult coho spawners following a few years of warm temperatures. The primary goal of this project is to quantify the effects of key environmental and biological covariates on coho marine survival and life history strategies. We will take advantage our unique, long-term dataset in a Bayesian framework to examine factors affecting coho survival and abundance. Ultimately, understanding the impacts of climate change on salmon populations and accurately predicting response of these populations to climate change is necessary for successful management, harvest, and conservation of these economically and ecologically important fishes. Because the Auke Creek provides censuses of migrating smolt and spawning coho, our dataset provides an unequalled resource to investigate factors affecting salmon survival.