Steelhead Trout (Oncorhynchus mykiss) - MMFS

Science Center Objects

Species Studied

Steelhead Trout (Oncorhynchus mykiss)

Juvenile steelhead smolts

Juvenile steelhead smolts become silvery and scales become loose as they transition into their seawater life history stages. Credit: Paul Hershberger, USGS - Western Fisheries Research Center. (Public domain)

Steelhead trout is an anadromous species that, unlike salmon, can spawn multiple years during the adult phase of its life cycle.  Populations of Puget Sound steelhead trout experienced dramatic population declines in recent years, prompting NOAA to designate them as a “Threatened Species” in Washington.  The causes of these recent population changes result from factors contributing to low early marine survival of smolts during their outmigration through Puget Sound.  These impacts are greatest among populations originating from south Puget Sound watersheds.  The Marrowstone Marine Field Station has partnered with NOAA – Fisheries, Manchester Research Station, Long Live the Kings, and Washington Department of Fish and Wildlife in an international effort (the Salish Sea Marine Survival Project) to evaluate causes of this early marine mortality.