Abstract
Understanding stock composition is critical for sustainable management of mixed-stock fisheries. When natural markers routinely used for stock discrimination fail, alternative techniques are required. We investigated the feasibility of using acoustic telemetry to estimate spawning population contributions to a mixed-stock fishery using Lake Erie’s summer walleye (Sander vitreus) recreational fishery as a case study. Postrelease survival was estimated after tagging and used to inform simulations to evaluate how contribution estimates could be affected by survival, sample size, and expected population contributions. Walleye experienced low short-term survival after tagging, but showed higher survival after 100 days, likely allowing fish to return to spawning areas the following spring. Based on simulations, accuracy and precision of population composition increased with an increase in the number of tagged fish released, and both appeared to stabilize when ≥200 tagged fish were released. Results supported the feasibility of using acoustic telemetry to estimate spawning population contributions to mixed-stock fisheries in Lake Erie.
Highlights
The ability to quantify population-specific harvest rates and identify source population(s) of harvested fish remains a challenging, yet important, issue for managing mixed-stock fisheries (Li et al 2015)
Walleye collection and tagging occurred in western Lake Erie during July–August 2015 (Figure 1)
Despite the short-term mortality experienced by walleye tagged in this study, 72% (13/18) of fish that survived after 30 days post-release were still alive during the 2016 spawning period (Figure 2 and 4)
Summary
The ability to quantify population-specific harvest rates and identify source population(s) of harvested fish remains a challenging, yet important, issue for managing mixed-stock fisheries (Li et al 2015). When harvest from a mixed-stock fishery is mistakenly assumed to be from a single population, unintended overexploitation can occur for small or less-productive populations and lead to inappropriate harvest regulations (Larkin 1979; Stephenson 1999; Li et al 2015). The collapse of Northwest Atlantic cod Gadus morhua may have been caused in part by failure to account for the existence of mixed-stock fisheries in assessment and management (Hutchinson 2008). Previous attempts to identify source populations of some Great Lakes mixed-stock fisheries using natural markers have resulted in varied success. Mixed stock analyses using genetic markers successfully informed lake trout Salvelinus namaycush restoration efforts in
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