Limited Demographic Effects One Decade After Implementation of a Harvest-Slot Length Limit for Walleye (Sander vitreus) in the St. Lawrence River, Québec, Canada

Abstract

Although the role of recreational harvest on size structure of declining fish populations is often unclear, bag and size limits are often implemented to prevent overharvest. Long-term monitoring and periodic assessments of stock status then become necessary to evaluate their potential impacts. Based on a long-term gillnet monitoring program in the St. Lawrence River, Québec, Canada, the effects of a 381–545 mm harvest-slot length limit implemented in 2011 were evaluated on walleye (Sander vitreus). Mixed-effects models revealed continued declines in the abundance of large walleyes, size distribution, total annual mortality, and female growth, condition, and size-at-maturity. Expected impacts were mostly not achieved, potentially because of environmental and trophic interaction changes in the St. Lawrence River, in addition to increasing fishing pressure. Our results highlight a need to reassess current walleye fisheries management strategies.