A Morphometric Approach for Stocking Walleye Fingerlings in Lakes Invaded by Rainbow Smelt

摘要

Invasive Rainbow Smelt Osmerus mordax have been associated with reductions in Walleye Sander vitreus recruitment, and predation by adult smelt on age-0 Walleyes has been identified as one of the potential mechanisms contributing to recruitment failure. Predation effects could be mitigated by stocking Walleye fingerlings based on smelt and Walleye morphometric relationships. By combining 0.95 quantile regression of smelt gape size on TL and 0.05 quantile regression of Walleye body depth on TL, we constructed a stocking tool to determine the appropriate size to stock Walleye fingerlings in lakes invaded by smelt such that few Walleyes are vulnerable to predation by smelt. In lakes where the largest smelt TL is known, Walleye fingerlings can be stocked according to the model: TLWYE = 0.819(TLRWS) -23.838. In cases where the smelt population size structure is unknown, Walleyes should be stocked at sizes larger than 142 mm, which would be a sufficient size for Walleye fingerlings to avoid predation by Rainbow Smelt in all lakes in this study.