Sacramento River Steelhead Trout: An Assessment of Behavioral Differences and Contributions of Hatchery and Wild Stocks

Start/End: September, 2008 to May, 2012

More than 625 Sacramento River steelhead trout (wild and hatchery, and juvenile and adult) were tagged and tracked in 2008-2011 to document their outmigration speeds, preferred outmigration routes and survivorship on these routes. Among the patterns to emerge: (1) Hatchery-born smolts (juveniles) take longer to outmigrate to sea than wild fish of the same age; (2) The main stem of the Sacramento River and Georgiana Slough are the two most common outmigration routes for both wild and hatchery fish; and (3) more than half of the adult hatchery steelhead released into the Sacramento River in 2010-2011 reached the San Francisco Estuary. In the project’s final year, the fellow will calculate survival rates along the full range of routes taken by fish, as well as return rates of adults. Preliminary analyses have already revealed surprisingly low rates of survival along the upper and middle sections of the Sacramento River, near where hatchery fish are released in Colusa.