Cutthroat Trout and Dolly Varden Rehabilitation in Western Prince William Sound. EXXON VALDEZ Oil Spill Restoration Project 98043B. Final Report

摘要

This study monitored habitat improvement projects over a four-year period to evaluate their effects on cutthroat trout and Dolly Varden abundance. In 1995 a total of 63-habitat improvement structures were installed in Prince William Sound at four different project locations. The enhancement project was intended to improve cutthroat trout and Dolly Varden habitat. Interspecific competition with juvenile coho salmon is believed to limit cutthroat trout production. Concerns were raised that habitat enhancements may increase coho salmon populations, thereby increasing competitive stress on cutthroat trout populations. The abundance of juvenile cutthroat trout, Dolly Varden and coho salmon were annually monitored using standard mark recapture techniques. However, bias in population estimates precluded their use in the final analysis; catch per unit effort information was used instead. We found that at only two locations, Otter Creek and Red Creek, could the increase in cutthroat trout and coho salmon abundance respectively, be attributed to the improvement work done in 1995. No significant negative trends in abundance for the three species were observed at any of the project locations. Stream enhancements such as cross-logs and particularly boulder clusters seemed to benefit cutthroat trout more than other types of improvements monitored in our study.