Steelhead Trout Smolt Survival in the Santa Clara and Santa Ynez River Estuaries
Steelhead trout (Onchorhynchus mykiss) populations on the Santa Clara and Santa Ynez rivers were historically two of the largest runs in southern California. These two runs also represent some of the best possibilities for restoration and preservation for southern steelhead. Southern steelhead smolts were tagged with acoustic and PIT tags on the Santa Clara and Santa Ynez Rivers during the spring of 2008 to assess their survival and residence time in estuaries. There was a 59% emigration survival rate on the Santa Clara River, and a 25% emigration survival rate on the Santa Ynez River. Surveys of water quality, potential smolt prey, and cover in both estuaries revealed that the major potential problems for smolts are high turbidity, high water temperatures, insufficient cover to hide from predators, and resident populations of avian predators. Recommendations for improving and assessing the runs are proposed, including management actions such as increasing water releases, further monitoring of smolt survival and estuary conditions in conjunction with management actions (adaptive management), and further research into the life-history of this important and critically endangered, but poorly understood fish.
Prepared for the California Department of Fish and Game (CDFG)