Genetic estimates of jurisdictional and strain contributions to the northeastern Lake Michigan brown trout sportfishing harvest Jared J. Homola a, ⁎, Alexander Samborski b , Jeannette Kanefsky a , Kim T. Scribner a,c a Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48864, United States of America b Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48864, United States of America c Department of Integrative Biology, Michigan State University, East Lansing, MI 48864, United States of America abstract article info Article history: Received 8 March 2019 Accepted 1 July 2019 Available online Communicated by: Wendylee Stott The Lake Michigan brown trout (Salmo trutta) fishery is sustained by the stocking of five hatchery strains by four state natural resource agencies. In the absence of exhaustive marking programs, strain-specific measures of stocking success are lacking for brown trout in Lake Michigan. We used microsatellite-based genetic assignment testing and genetic stock identification (GSI) to determine the strain of 122 angler-caught brown trout from four northeastern Lake Michigan ports. We compared strain composition estimates for sportfishing harvest to ex- pected proportions of each brown trout strain in Lake Michigan at the time of harvest using stocking records corrected for age-specific mortality rates. Reassignment rates of individuals from baseline strains averaged 92.1% (range: 84.1–98.0%). Assignment testing and GSI analyses consistently found Wild Rose strain brown trout represented approximately 89% of the northeastern Lake Michigan sportfishing harvest, while only com- prising 43.8% of the expected stock. Of the Michigan angler harvest of Wild Rose strain brown trout, approxi- mately half were estimated to have originated from Wisconsin hatcheries, demonstrating a propensity for lake-wide movements. Continued assessments will improve understanding of strain relative contributions to an- gler harvests that can direct future stocking efforts. © 2019 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Keywords: Microsatellite Brown trout Lake Michigan Great Lakes Introduction Genetic data provide a means of determining the origin of individual fish, particularly when physical tagging is infeasible or contributing groups are morphologically indistinguishable. The ability to quantify contributions from various sources to an unmarked group of individuals using genetic data (i.e., mixed stock analysis; Kalinowski, 2004) pro- vides insights into species' movement patterns (e.g., Homola et al., 2012a) and can also inform fisheries management. For instance, unin- tentional harvest of non-target populations can be identified (Bott et al., 2009; King et al., 2016) or success of source populations can be assessed based on relative contributions to targeted assessments (Scribner et al., 2018) or harvest (Bradbury et al., 2016). The Lake Michigan brown trout (Salmo trutta) fishery relies heavily on fish stocked from hatcheries around the basin (Keller et al., 1990). Brown trout are a non-native species that was introduced to the Lauren- tian Great Lakes region from Europe in the late 1800s (Scott and Crossman, 1998) and has since been perpetuated using several hatchery strains. In Lake Michigan, stocked brown trout originate from five strains stocked by four states: Plymouth Rock (Indiana and Illinois), Gilchrist Creek (Michigan), Wild Rose (Michigan and Wisconsin), Seeforellen (Michigan and Wisconsin), and Sturgeon River (Michigan). While stocking numbers and locations for each brown trout strain are known, information about strain-specific contributions to recreational fisheries is currently lacking. These data have traditionally been difficult to attain due an inability to morphologically distinguish the strains and the lack of standardized brown trout marking programs. However, pre- vious research indicated sufficient genetic differentiation exists among strains to facilitate a mixed stock analysis (Homola et al., 2012b) to es- timate strain rates of return to anglers' creels. The purpose of this research was to quantify strain contributions to brown trout recreational harvest at four northeastern Lake Michigan ports in Michigan and to evaluate whether strains were harvested pro- portional to stocking rates that are adjusted for age-specific mortality rates. Disparities between stocking and harvest rates would suggest dif- ferential strain survival or vulnerability to angling and may be useful for adaptively managing ongoing brown trout stocking efforts in Lake Michigan. We also compared the genetic diversity and differentiation among the hatchery strains. ⁎ Corresponding author. E-mail address: homolaj1@msu.edu (J.J. Homola). https://doi.org/10.1016/j.jglr.2019.07.007 0380-1330/© 2019 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr Journal of Great Lakes Research 45 (2019) – 998 1002 July 2019 20