Loss of Floy Anchor Tags from Lake Whitefish

Abstract Rate of loss of the Floy anchor tag (FD-68C) was estimated as part of a study of the population dynamics of lake whitefish (Coregonus clupeaformis) in Lake Michigan. Estimated tag loss increased from 11.1% for fish at large for 1 year to 20.5 and 18.9% for those at large for 2 and 3 years, respectively. Possible causes of tag loss were commercial gill nets, growth of a filamentous algae on tags, insecure attachment because of rough seas during tagging, and unfamiliarity with the tagging system. A correction for tag-loss rate in estimates of mortality and yield increased the estimated exploitation and fishing mortality rates by 17% and yield per recruit by 40%.