Comparative Life History Characteristics of Hatchery and Wild Steelhead Trout (<i>Salmo gairdneri</i>) of Summer and Winter Races in the Kalama River, Washington

Abstract

Life history information was collected from adult upstream migrant hatchery and wild steelhead trout (Salmo gairdneri) of summer-run and winter-run racial origin in the Kalama River, Washington, from 1976 to 1984. We found inter- and intraracial distinctions among many of the characteristics examined. In contrast with winter steelhead, summer steelhead generally had a temporally protracted time of return, fewer total age categories, fewer repeat spawners, and greater size at a given marine age. Compared with wild steelhead, hatchery steelhead generally had fewer saltwater age categories and a lower incidence of respawners. Based on differences in return timing, age composition, and size at maturity, we suggest that greater similarities currently exist between Kalama River hatchery and wild summer steelhead than between hatchery and wild winter steelhead.