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Evaluating short-term survival of walleye implanted with acoustic transmitters at elevated temperatures
Matthew D. Faust1, Christopher S. Vandergoot2, and Richard T. Kraus2
1Ohio Department of Natural Resources, Division of Wildlife, Sandusky Fisheries Research Station, 305 East Shoreline Drive, Sandusky, Ohio 44870
2United States Geological Service, Great Lakes Science Center, Lake Erie Biological Station, 6100 Columbus Avenue, Sandusky, Ohio 44870
Lake Erie’s walleye population contains numerous discrete spawning aggregations (stocks) that become mixed outside of the spawning period. Previous attempts to differentiate among these stocks using natural markers (e.g., otolith microchemistry, genetics) had limited success. Herein, we test the ability to use acoustic telemetry as a novel stock discrimination method by evaluating survival of walleye captured via angling and tagged at elevated water temperatures (i.e., > 20°C). Thirty walleye were collected from western Lake Erie during July–August 2015 and implanted with acoustic transmitters using an established surgical protocol, used successfully to tag hundreds of walleye previously with minimal post-release mortality. Fish were released into an array of 25 acoustic receivers, and individual detection histories were used to estimate short-term survival (i.e., 30-day). Mean water temperature at capture was 26.0°C and ranged 21.4 to 28.4°C. Total survival was 60% (18/30), which was similar to survival of walleye caught in live-release tournaments during summer months. Despite high mortality experienced by tagged fish, several surviving fish were detected during the 2016 spawning period at two locations that support large aggregations of walleye, which served as proof-of-concept to the idea that acoustic telemetry can be used to estimate stock contributions to a fishery. Given that the success of such an approach depends on an ability of researchers to minimize mortality of tagged fish, we developed guidelines that seek to minimize the stress of capture and tagging based on our experience and published recommendations for walleye and other fishes.