Contribution of muskeg channel habitats to juvenile coho salmon production in the Situk River, Alaska

Abstract

This study examines seasonal patters of habitat use by juvenile coho salmon in the Situk River and the importance of muskeg channels. To determine seasonal patterns I trapped fish from a range of habitats every two weeks during the summer of 2005. Analysis of the length-frequency data these samples provided showed most fry emerged in gravel bedded channels and that a substantial number of these fish then moved into muskeg channels during their first summer, rearing there until smolting at age 1 + or 2+. To estimate the number of coho salmon using muskeg channels, I established a relationship between channel width and fish density and scaled this up to the entire drainage using GIS analysis. This demonstrated that muskeg channels provide important rearing habitat. Comparison with published data suggests that muskegs are responsible for between 14% and 80% of total coho salmon smolt production in the Situk River.