Do angler catch and harvest rates differ between open water and ice anglers in Wisconsin?

Understanding seasonal differences in species-specific vulnerabilities to recreational angling can be important for informing sustainable fisheries management practices, like fishing seasons or season-specific regulations. However, comparisons of angler catch and harvest rates among seasons with disparate modes of fishing, like open water and ice angling in north-temperate lakes, are lacking. We used all available Wisconsin Department of Natural Resources point-intercept creel survey data during 1990–2020 to test for seasonal differences in the fisheries for five species targeted by open water and ice anglers in Wisconsin, USA, lakes (black crappie Pomoxis nigromaculatus, bluegill Lepomis macrochirus, northern pike Esox lucius, walleye Sander vitreus, yellow perch Perca flavescens). Specifically, we tested for: 1) species-specific differences in mean open water versus ice angling catch and harvest rates; 2) trends in species-specific mean open water versus ice angling catch and harvest rates during 1990–2020; and 3) monthly patterns in mean species-specific angler effort and catch rates. Mean angler catch rates of the five study species were significantly higher during the open water season and mostly temporally stable – only black crappie and bluegill open water catch rates and black crappie ice season catch rates significantly increased during 1990–2020. Mean angler harvest rates were significantly higher in the open water season for black crappie, bluegill, and walleye. Harvest rates were significantly higher during the ice season for northern pike and did not differ between seasons for yellow perch. Harvest rates were mostly temporally stable across species, although harvest rates declined for bluegill ice fishing and yellow perch in both seasons. Species-specific angler effort and catch rates mostly corresponded with seasonal (spring/early summer) vulnerabilities of our study species, although higher winter effort and catch rate patterns for northern pike and yellow perch may suggest unique harvest preferences for those species. Our results suggest that ice angling should not be assumed to have a negligible influence on fish populations in north-temperate lakes, fisheries-dependent and -independent monitoring data should be jointly considered when assessing fish population status, research on the human dimensions of ice fisheries is critically needed, and angler knowledge of seasonal fish vulnerabilities are generally coupled with higher fish catch rates.