Freshwater life-cycle timing of Pacific salmon and steelhead (Oncorhynchus spp.) in Canada

Abstract

Information on species’ phenology and distribution is essential for assessing and mitigating exposure to pressures that vary over space and time, such as development projects or climate changes. Pacific salmon (Oncorhynchus spp.) have complex life cycles that span freshwater and marine environments and unfold over several years and many thousands of kilometers. Currently, there is no central repository of life-cycle timing for salmon and steelhead populations throughout their Canadian range, hindering conservation and recovery efforts. To fill this gap, we have compiled timing data for fry migration from incubation to rearing grounds, juvenile migration from rearing grounds to the ocean, adult entry into rivers, and spawning for salmon and steelhead from British Columbia and the Yukon, Canada. For each species, we analysed the compiled data using linear models to describe patterns in population-specific timing across latitude, distance from the ocean, river gradient, and life-history types. Although we found significant data gaps in remote regions, our compiled dataset represents the best-available information on life-history timing that can inform environmental planning and salmon conservation actions.