Lake Trout Movements in U.S. Waters of Lake Huron Interpreted from Coded Wire Tag Recoveries in Recreational Fisheries

Lake trout management and restoration make use of age-structured population models that incorporate parameters to represent movement among management areas, and harvest quotas are based on proportions of stocked fish remaining in and moving out of areas of release. We investigated movements of lake trout in U.S. waters of Lake Huron based on spatial and temporal distributions of coded-wire-tag (CWT) recoveries by trip in recreational fisheries using Generalized Linear Models (GLMs). For the analysis, we incorporated as model predictors the area, month, year, and source of CWT recovery, which included reports by charterboat captains, creel-clerk interviews of non-charter anglers, and “headhunter” (CWT collection specialist) samples from charter and non-charter catch. Results indicated that CWT recoveries by trip were lowest from charterboat operators, followed by recoveries from creel clerks (2× captain reports), headhunter non-charter (3×), and headhunter charter (9×). Standardized recovery levels were highest in the management area of release and one area immediately adjacent, with remaining percentages decreasing with distance from release. CWT recovery levels decreased from May to September and suggest seasonal movement among areas that have implications for stock assessment. From standardized recoveries, we estimated that 40% of the CWT lake trout were recaptured in areas where released and others moved north, south, and southeast. Our results indicate that higher proportions of lake trout move out of release areas fish than previously shown and suggest that prior studies may be biased, in part due to lack of standardization among tag recovery sources and ignoring seasonal movements.