Characterizations of local populations of steelhead trout in two south-central Lake Superior streams

This study characterizes populations of steelhead trout (Oncorhynchus mykiss) in two streams in the South-Central Lake Superior watershed.  Steelhead trout were introduced to the Great Lakes in the 1870’s and are potential competitors with native brook trout (Salvelinus fontinalis). Our laboratory is monitoring the effects of exotic salmonid removal, including steelhead trout, on the brook trout population in Sevenmile Creek as part of a long term coaster brook trout rehabilitation project.  Data collection began for the rehabilitation effort in 2004 in Sevenmile Creek and Mosquito River from which we determined fish condition, population structure, habitat use, and movement patterns.  The steelhead trout in these populations smolt and migrate at 2+ years of age, usually outmigrating in May and June.  The iteroparous adults return to the streams to spawn in late March and early April initially at age 3-4; spawners are present into June. Steelhead trout distribute differently in the two streams; juvenile steelhead trout are distributed throughout Mosquito River while in Sevenmile Creek they are shifted toward downstream reaches.  The data were also used to develop population estimates for both populations in the study; and the effects of the removal project were assessed.