Reducing the Incidental Catch of Lake Trout in Large-mesh Gill-net Fisheries for Lake Whitefish

FWS Agreement Number

30181-A-G016 (F10AP00080)

Summary

This pilot study was conducted to determine whether standard gill nets modified to fish four (4) feet off the bottom would reduce by-catch of lake trout while maintaining an economically viable catch of lake whitefish. A total of 41 gangs, each comprised of equal footage of the modified gill net (MGN) and standard gill net (SGN), were deployed during 2009 – 2011 in Keweenaw Bay, Lake Superior. A hierarchical, generalized linear mixed model (GLMM) was used to determine whether the catch of lake trout and lake whitefish differed by gear type. Compared to the SGNs, the MGNs reduced catch of lake trout by 68% and the catch of lake whitefish by 50%. A 50% reduction (i.e. an estimated 49,418 pounds) in catch of whitefish, the target species, would affect the economic viability of the tribal fishery. A 68% reduction in catch of lake trout (i.e. an estimated 31,151 pounds) could be beneficial if a need existed that outweighed the cost of the reduced whitefish catch. However, such a need does not exist in Michigan management units MI-2 through MI-5 within 1842 ceded territory waters of Lake Superior where lake trout populations are recovered and tribal harvest of lake trout is effectively managed to stay within the tribal quota.