Walleye in the Grand River, Ontario: an Overview of Rehabilitation Efforts, Their Effectiveness, and Implications for Eastern Lake Erie Fisheries

摘要

Walleye (Sander vitreus) from the Grand River (Ontario) are recognized as genetically and physiologically distinct from other Lake Erie stocks. The low abundance of these walleye in the early 1980s triggered rehabilitation efforts that included intensive research, transfers of walleye from the Thames River (Ontario), supplemental stocking from local hatcheries, construction of a fishway, and creation of additional spawning habitat. Walleye migrating from Lake Erie are currently hindered from reaching 90% of potential riverine spawning habitat by a dam 7 km upstream. Although increased walleye catch rates were reported following construction of a fishway in 1995, recent assessment has shown that access is still severely restrained. Catch rates of young-of-the-year walleye during fall surveys have increased notably since 1999, coincident with direct transfers of mature adults over the barrier. Recent successful year classes have contributed to a population dominated by young (< 5 y) fish. Genetic analyses show that fish culture contributed between 3% and 25% to five recent year classes of Grand River walleye. Facilitating access to spawning habitat above the Dunnville dam may be the most effective way to increase the productivity of this stock, with consequent strengthening of walleye fisheries and the fish community in the eastern basin of Lake Erie.