Project Summary
Climate change and angling pressure are predicted to be two of the greatest threats to game fish species in North America. One species particularly vulnerable to these threats are walleye (Sander vitreus). Walleye are widely distributed across Canada, and are an important ecological, commercial, and recreational fish species. Understanding how threats such as climate change and angling pressure impact walleye will help guide future management. Our research objectives are (1) Determine how climate change affects the fitness of walleye in Canada, and (2) Determine how angling pressure affects the abundance of walleye in Canada. To address these objectives, we sampled 100 lakes from across Canada within the native range of walleye. Mean fitness (total length) and relative abundance (catch per unit effort) of walleye were measured in each lake to assess the effects of temperature, angling pressure, and lake depth. Non-linear regression suggests that walleye fitness is optimized in the middle of temperature extremes (hot and cold). An analysis of covariance (ANCOVA) revealed a strong interaction effect between depth and angling pressure. Results from these analyses indicate that climate change will have a non-linear effect on walleye fitness, as some fish will increase or decrease in total length depending on baseline temperatures. Furthermore, walleye abundance is strongly influenced by the interaction between angling pressure and lake depth.
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