Factors influencing the hooking mortality of walleyes caught by recreational anglers on mille Lacs, Minnesota

Abstract Recent implementation of size-based regulations in recreational fisheries for walleye Sander vitreus have led to more released walleyes and presumably to more losses of released fish. We conducted this study to estimate hooking mortality in Mille Lacs, Minnesota, and to determine factors that influence the survival of released walleyes. Volunteers and Minnesota Department of Natural Resources employees sampled walleyes with common angling methods in 2003 and 2004 on Mille Lacs (n = 1,246). Simple hooking mortality rates ranged from 0% (95% confidence interval = 0–1.8%; n = 204) in May, when lake water temperatures were less than 20°C, to 12.2% (9.2–15.9%; n = 392) in the July–August period, when lake water temperatures were at least 20°C. We used logistic regression within generalized linear or additive models to determine influential variables. Hooking mortality was most associated with water temperature, bleeding, fish length, hook location, and fish floating upon release. Mortality increased a...