Population Dynamics of Lake Trout in Priest Lake, Idaho

Lake Trout Salvelinus namaycush were introduced to Priest Lake, Idaho, during the 1920s, but remained at low abundance until the introduction of Mysis diluviana in the 1960s.  The subsequent decline of the popular kokanee Oncorhynchus nerka fishery was attributed to increased survival of young Lake Trout due to mysid introduction.  By the 1990s, Lake Trout dominated the recreational fishery in Priest Lake.  The first fishery-independent estimate of Lake Trout abundance was conducted in spring 2013.  Structures for ageing were also collected during this sampling event to estimate population age-structure, growth rates, and mortality rates.  Maturity status and fecundity were estimated during a supplemental autumn sampling event, prior to peak spawning.  An age-structured population model was constructed using these demographic data and data from the literature.  This model was then 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 limits).  These models will allow managers to quantitatively assess management strategies and determine the best course of action for Lake Trout management at Priest Lake.  This research also contributes to the broader understanding of nonnative, exploited Lake Trout populations in the Western U.S.