Abstract.-Trap nets have been promoted as an efficient means for harvesting lake whitefish Coregonus clupeaformis in the Great Lakes while limiting mortality to other (non-target) species. All state-licensed fisheries for lake whitefish in Michigan waters of Lake Superior use trap nets. During 1983-1989, these fisheries were sampled annually to estimate catch and mortality of non-target species. The samples represented 9% of the total trap-net effort by these fisheries. Non-target fishes killed annually by state-licensed trap nets in Michigan waters of Lake Superior, with mean annual catch in parentheses, were estimated as: 131 (19,721) sublegal lake whitefish, 414 (11,341) lake trout Salvelinus namaycush, 26 (37) coho salmon Oncorhynchus kisutch, 6 (15) chinook salmon 0. tshawytscha, 6 (11) rainbow trout 0. mykiss, 12 (55) brown trout Salmo trutta 41 (143) lake herring Coregonus artedii, 39 (67) round whitefish Prosopium cylindraceum, and 0 (48) lake sturgeon Acipenser fulvescens. All dead fish were gilled in the pot portion of trap nets. The only non-fish species observed in trap nets was the common loon Gavia immer. The estimated annual catch of common loon was 263, with 86% of these caught in trap-net hearts. The morality rate for loons in trap nets was 100%. No modifications of trap nets or fishing restrictions were recommended to reduce catch and mortality of non-target fishes in Lake Superior. However, we recommend that mesh size in the top of the hearts be increased to 14-in stretch mesh to reduce catch ant mortality of common loons.