Evaluation of Protected Slot Limits for Walleye on Two Large Lakes in Minnesota

Protected slot limits (PSL) are a popular restrictive regulation for walleye sport fisheries in Minnesota.  We evaluated two large lake walleye fisheries, Rainy Lake and Lake Winnibigoshish, that have the longest time series of post-regulation data available.  Cass Lake, a nearby large lake that has kept the standard state-wide regulation, was included into this analysis as a reference lake.  We utilized annual population assessment and creel survey data to determine population and fishery changes.  Analysis of creel survey data indicate that catch rates have generally increased, especially for larger fish.  There have been decreases in harvests overall, though much of the decline in harvest is likely due to concomitant declines in fishing pressure after the regulations were implemented so angler harvest rates (lb/h) before and after the PSL are comparable.  Analysis of assessment data indicated that spawner abundance and biomass generally increased, and there has been relatively consistent recruitment of strong year classes.  Overall, the implementation of protected slot limits on these two, large-scale fisheries achieved the overall objectives of reducing harvest while increasing the abundance and catch rates of larger fish.