The goals of this study are to develop methods to reduce wandering and straying of steelhead (Oncorhynchus mykiss) that are collected and barged from the Snake River to below Bonneville Dam. Salmon and steelhead that stray and spawn in non-natal streams are a significant conservation concern, because they may confound accurate assessment of the VSP parameters of recovering native populations and decrease the productivity of these populations through genetic introgression or ecological competition. These issues are a particular concern for listed mid-Columbia River stocks because salmon that are collected and barged downstream as juveniles have shown higher stray rates into these watersheds as returning adults relative to in-river migrants.

However, while barging may contribute to elevated stray rates, there are substantial benefits from barging because transported Snake River steelhead consistently have higher smolt-to-adult returns than steelhead left to migrate in-river. Therefore, it is important to identify and develop strategies for reducing the stray rates of transported steelhead while maintaining the survival benefits consistently observed for barged steelhead. The specific aims of this proposal are as follows:

1) Conduct an analysis of existing coded wire (CWT) and PIT tag data to identify causative factors associated with straying by Columbia River salmonids, particularly as it relates to natural rates of straying and straying associated with transport.

2) Assess imprinting of barged and in-river migrants by monitoring imprinting associated changes in physiological function and gene expression as indicators of imprinting success.

3) Identify key environmental parameters (e.g. orienting current, water exchange rate, novel tributary water) that are important for imprinting barged fish and develop barging protocols to optimize imprinting success and thereby minimize straying using a controlled laboratory study.

4) Initiate tests of a modified barge protocol designed to maintain survival benefits while reducing wandering, delay, and straying behavior of returning adults. The work is being conducted by NWFSC scientists in collaboration with the University of Washington.

Products for this project will include annual reports, peer-reviewed publications, presentation of results at local and national meetings, and consultation with the FCRPS managers.

Physiological and field data on barged and in-river migrant steelhead.