Effects of Commercial Fishing on an Unexploited Lake Whitefish Population inMichigan's Waters of Lake Superior, 1983-1989

摘要

Population parameters for a previously unexploited population of lake whitefishCoregonus clupeaformis at Upper Entry in Michigan waters of Lake Superior were measured in catches from a state-licensed trap-net fishing. A tribal gill-net fishery began on these lake whitefish in 1984. Annual trap-net catch decreased from 380,000 lb in 1984 to 44,000 lb in 1989. Catch per trap-net lift decreased from 690 lb in 1983 to 159 lb in 1989. Although age decreased from 8.9 years in 1984 to 6.4 years in 1989. Modal age of lake whitefish in tap-net catches was 9 years in 1983 and 1984, 10 years in 1985, then decreased to 6 or 7 years during 1986-1989. Length-at-age of lake whitefish at Upper Entry was less than for exploited populations elsewhere in Lake Superior, and decreased during 1983-1987 as faster growing individuals of the initial stock were harvested. Lake whitefish at Upper Entry were not fully vulnerable to the 19-inch size limit until age 10.