This is an international, scientific effort to identify the mechanisms responsible for the production of Pacific salmon. The proposed research directly addresses the production objectives of the Pacific Salmon Treaty by identifying the factors limiting production of all five species, estimating stock specific biomasses and ultimately (assuming multiple years of surveys) using these estimates to forecast adult returns. This 2019 survey and application of winter trawl surveys in the NE Pacific should be considered a ‘proof of concept’ effort to test the capability of such studies. There is a growing recognition that size-dependent mortality within the first ocean year regulates Pacific salmon production, which also means that environmental influences are greater in the first ocean year. The general hypothesis that many investigators are testing as the mechanism that regulates Pacific salmon production, is the critical size, critical period of hypothesis (Beamish and Mahnken 2001, Beamish et al. 2004, and Farley et al. 2007).
We note that this is the first time these winter observations have been made in the Gulf of Alaska and the testing of the hypothesis will help with the understanding of the mechanisms regulation production. Importantly, this information also has stand-alone relevance as it will be available to the science community for the first time.