Environmental and genetic influences on fitness-related traits in a hatchery coho salmon population.

Many natural and managed organisms will require substantial functional genetic variation to respond to selection in the face of rapid environmental change. Pacific salmon have experienced strong fluctuations in critical fitness traits over the past five decades. We examined genetic and phenotypic variability over three generations in a pedigreed hatchery population of coho salmon (Oncorhynchus kisutch) by monitoring seven fitness-related traits. Three-year-old adult return numbers varied more than five-fold, and jack (2-year old males) numbers varied 13-fold. Body sizes of Inch Creek coho salmon decreased consistently such that fish were only 40.7% as heavy in 2015 as in 2006 and female reproductive traits also decreased. During the study period, the majority of families produced returning adult progeny and effective population size was relatively constant. Heritability estimates for phenotypic traits were significantly greater than zero except for condition factor, and the estimated heritability for jacking was 0.42. The Inch Creek coho salmon population harbours substantial heritability for fitness and reproductive traits and thus likely retains significant capacity for adaptation despite many years of hatchery propagation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author