Assessing Effects of Supplementation on Fitness of Sockeye Salmon in Auke Creek, Alaska

The overarching goal of this joint project by the University of Alaska and the Alaska Department of Fish & Game is to use parentage-based tagging over three generations of experimental hatchery supplementation to quantify differences in fitness between wild and hatchery-origin sockeye salmon in Auke Creek, Alaska. Secondary goals of this research are to test for second-generation differences in fitness between wild and hatchery-origin individuals that spawn naturally, and to quantify changes in genetic diversity and population structure in the wild sockeye salmon population as a result of three generations of hatchery supplementation. Results of this study will provide information critical for assessing the relative costs and benefits of hatchery supplementation in managing sockeye salmon populations subject to the Pacific Salmon Treaty.
To date, no study has attempted to quantify fitness differences between hatchery and wild sockeye salmon. Auke Creek provides the ideal setting in which to measure changes in fitness resulting from hatchery supplementation of sockeye salmon for a number of reasons: 1) Auke Creek is located on the road system in Juneau, Alaska, making field sampling cost-effective; 2) the weir at Auke Creek allows researchers to sample all adults returning to spawn in the Auke Creek drainage – this is critical as it allows complete genotypic sampling of all parents and offspring; 3) the Auke Creek sockeye salmon population is relatively small (recent average is 2,666 individuals), making complete enumeration feasible; 4) a downstream smolt weir in addition to the upstream adult weir makes further exploration of potential mechanisms for fitness differences possible; and 5) results from this study are likely to be applicable to other sockeye salmon hatchery projects within the geographical region subject to the PST. 2016 is year 3 of the proposed 3-year program.