Managing adult hatchery summer steelhead for a recreational fishery with reduced hatchery and wild interactions

Graduation date: 2009Hatcheries whose purpose is to provide for a recreational fishery must minimize impacts on wild fishes. Management to reduce hatchery and wild interactions is especially important on river systems that contain Endangered Species Act (ESA) listed species. I examined adult hatchery summer steelhead, Oncorhynchus mykiss, behavior, current management and a potential future management practice in a river with both introduced and ESA listed steelhead. I used radio telemetry to determine hatchery summer steelhead activity, behavior, and examine management tactics in the Clackamas River, Oregon. I evaluated the movement and distribution of radio-tagged fish between July 2007 through January 2008 using a combination of fixed and mobile radio-tracking. In addition, I used electromyogram (EMG) transmitters to record activity and behavior while the fish were holding in their natal river. An EMG-tagged fish was caught on hook and line during tracking and is the first known instance of estimated activity levels during capture.\ud I evaluated the fish recycling program on the Clackamas River. Recycling involves the transport and release of adult steelhead back downstream following their collection at the hatchery to increase angler success. I estimated that up to 41% of recycled fish were caught in the recreational fishery. However, the majority of fish (44 -67%) were unaccounted for after release and may negatively affect wild populations. The Oregon Department of Fish and Wildlife is investigating the feasibility of sterilizing returning adult hatchery steelhead to reduce hatchery and wild interactions and increase recreational fishing opportunity. To evaluate the effect of sterilization on adult fish behavior, I gonadectomized and radio-tagged 40 hatchery summer steelhead and monitored their behavior and contribution to the fishery compared to sham-operated fish. Gonadectomized fish remained in the river, were distributed downstream of control fish, and were caught in the recreational fishery. Based on my results, I conclude that sterilization may be a useful technique to improve angler opportunity while minimizing the impact to wild fish. Behavior and activity of hatchery fish and their responses to management procedures should be closely monitored to better manage hatchery fisheries