Evaluation of Hatchery-Reared Brook Trout Stocked in the Upper Peninsula ofMichigan

摘要

Population estimates and creel surveys were conducted two years before (1988-89)and three years after (1990-92) stocking individually tagged, hatchery-reared brook trout Salvelinus fontinalis in three streams (East Branch Escanaba, West Branch Escanaba, and Middle Branch Ontonagon) in Michigan's Upper Peninsula. Similar data were collected on the Iron River, which was not stocked, as a study control. We related densities and catch rates of feral brook trout to average daily temperatures, groundwater yield and physical stream parameters. We measured fish health parameters in samples of hatchery-reared and feral brook trout for comparison. The purpose of our study was to evaluate impacts of stocked fish on sport catches and feral brook trout populations. Estimated numbers (plus or minus 2 SE) of legal-sized brook trout were significantly greater during the stocking period (1990-92) than during the pre-stocking period (1988-89) and were not significantly different in the control river between the two periods. Brook trout catch per hour increased an average of 79% and catch increased an average of 72% after stocking in the East Branch Escanaba, West Branch Escanaba, and Middle Branch Ontonagon rivers combined.