Characterizing the Angling and Tribal Spearing Walleye Fisheries in the Ceded Territory of Wisconsin, 1990–2015

Abstract

AbstractAssessment of the Walleye Sander vitreus angling and tribal spearing fisheries in the Ceded Territory of Wisconsin (CTWI) is critical for the sustainability of this resource. Key to these assessments is an understanding of harvest demographics, exploitation, catch and harvest efficiency, and relationships between catch or harvest and adult density. We characterized the size distribution and mean length of harvested Walleyes, harvest, exploitation rate, and catch (angling) or harvest (spearing) rate for both fisheries during 1990–2015. Then, we evaluated catch and harvest rates in relation to adult density and tested for self‐regulation or hyperstability in each fishery. Size distribution and mean length of harvested Walleyes in both fisheries were statistically different but biologically similar. Anglers harvested significantly more Walleyes, and the mean exploitation rate was greater in the angling fishery. Spearfishers had significantly higher mean harvest rates compared with angler catch rates. Catch and harvest rates followed an asymptotic relationship with adult density, with the spear fishery showing more hyperstability than the angling fishery. In the CTWI, naturally reproducing Walleye populations are managed for densities ≥7.4 adults/ha. Our results suggest that maintaining adult Walleye densities near the point of diminishing returns of the asymptotic relationship (10–15 Walleyes/ha) will result in a sustainable fishery that also maximizes tribal harvest and angler catch. However, maintaining adult Walleye densities within this range in the unproductive lakes typical of the CTWI may be unrealistic. Due to the hyperstability observed in each fishery, active management of the spear fishery should continue and monitoring of the angling fishery should also continue given recent declines in natural recruitment and production observed in the CTWI in order to maintain Walleye populations in a “safe operating space.” An empirical understanding of CTWI Walleye angler and spearfisher effort dynamics is critically needed to mechanistically explain the observed hyperstability in each fishery.