Conservation Genetics of Steelhead Trout: Variation in Reproductive Success in Small Populations

Bentzen

9903914

The goal of this project is to determine the factors that influence the reproductive success of steelhead trout. Is reproductive success random, or do some individuals produce most of the offspring that survive to maturity? It is hypothesized that large males will dominate access to females and will have most offspring, and females breeding after the stream's winter floods subside will be most successful. It is also hypothesized that hatchery-produced fish will be less successful than wild fish. DNA fingerprinting techniques will be used to determine the number of offspring from parents that survive all the rigors of life in freshwater and at sea to return and start a new generation.

Many populations of steelhead trout and their close relatives, the Pacific salmon, are in serious jeopardy; several are already listed under the Endangered Species Act. One response to these population declines has been to produce fish in hatcheries for recreational and commercial fisheries. This project will evaluate the current practice of enhancing steelhead populations with hatchery-produced fish. These steelhead differ from wild fish in the timing of spawning and body size--two traits hypothesized to affect reproductive success. The study will help determine the best practices for conservation of steelhead and salmon populations.