Catch and effort variation in the commercial gillnet fishery of Lake Winnipeg, Canada, in relation to environmental factors

Abstract

The impact of environmental factors on the fishing effort and catch rate of sauger (Sander canadensis) and walleye (Sander vitreus) was examined for the commercial fishery of Lake Winnipeg's south basin. Time was represented biologically as degree days. The influences of light intensity, wave height, barometric pressure, and the discharge rate of the Red River were examined using generalized linear models with the quasi-family of distributions. The percentage of the null deviance was found to be an appropriate selection criterion for choosing variables to include in the models. Effort declined throughout the early fishery and declined with increasing winds later in the year. Walleye catch rate declined through the early season. Sauger catch rates increased and then declined as the early season progressed and were associated with indicators of decreased light intensity. The relationship between catch rate and each statistically significant environmental variable was consistent with the habitat preferences of the species under examination.