Use of Genetics to Aid Management of Coaster Brook Trout

Historical accounts indicate that coaster brook trout Salvelinus fontinalis were once plentiful in Lake Superior, but by the late 1800s populations were substantially reduced and have remained low for nearly a century.  A recent resurgence of interest by Lake Superior anglers and fish management agencies led to the publication of A Brook Trout Rehabilitation Plan for Lake Superior by the Great Lakes Fishery Commission.  In Minnesota, anglers applied heavy pressure to stock brook trout as the primary rehabilitation tool, but managers resisted stocking before an initial coaster assessment could be implemented.  In 1997 a fall electrofishing survey was conducted to determine if remnant coaster stocks were still present. Mitochondrial DNA analysis suggested that remnant stocks persisted, and strategies were implemented to protect the coaster stocks from over-harvest with restrictive regulations, and increased habitat protection.  Subsequent surveys indicated a shift in age-structure, size-structure, and CPE of coasters greater than 356 mm (14 inches).  In the most recent survey (2007/2008) microsatellite genetic analysis was conducted to determine the origin of the larger brook trout.  This analysis indicated 95% of all fish sampled, and 90% of fish greater than 356 mm were wild fish, and not strays from other agencies’ coaster stocking programs.