Harvest and Reproductive Output Regulate Nonnative Lake Trout Population Growth: Implications for Management

Lake Trout Salvelinus namaycush management is challenging because of the high predatory demand and long life span of individuals.  Lake Trout were introduced to Priest Lake, Idaho, during the 1920s, but remained at low abundance until the introduction of Mysis diluviana.  Although Priest Lake has experienced dramatic changes in the fish community, little fishery-independent information is available.   The objectives of this study were to describe the current Lake Trout population status and to evaluate management scenarios using simulation.  A mark-recapture study was conducted in spring 2013.  Otoliths and fin rays were collected to estimate population age-structure, individual growth rates, and total annual mortality.  Maturity status and fecundity data were collected in autumn, prior to peak spawning.  An age-structured population model was constructed using these demographic data and data from the literature.  The model was used to assess population growth rates under several management strategies, including Lake Trout removal efforts of varying intensity and different harvest regulations (e.g., slot limit).  Results indicate signs of density-dependent limitations in population growth.  We also identified biological limitations and population-level consequences of several management scenarios.  More broadly, this research provides insight into the drivers of Lake Trout population regulation, including harvest and reproductive output