Lake Ontario August gillnet survey and Lake Trout assessment, 2022

Lake Ontario Lake Trout (Salvelinus namaycush) rehabilitation has been annually assessed with fishery independent surveys since 1983, in an effort to evaluate program benchmarks and compare observations with management objectives. These surveys provide information on the abundance, strain composition, and condition of the adult Lake Trout stock, as well as information on levels of natural recruitment, Sea Lamprey (Petromyzon marinus) wounding rates, and abundance indices of other coldwater fish species (Burbot Lota lota, Cisco Coregonus artedi, and Lake Whitefish C. clupeaformis). In 2022, the catch per unit effort (CPUE) of total Lake Trout in gillnets remained high (18.9 fish/lift; highest since 1998) compared to lows observed during 2005–2009 (average = 7.5 fish/lift). The CPUE of immature Lake Trout in the 2022 survey was the highest since 1994. Wild-produced mature Lake Trout remain rare in the adult population (2.4% of adult catch). Strain composition of stocked fish indicated more than half (56%) of all coded-wire tagged Lake Trout captured in 2022 were from the Superior Klondike strain. Sea Lamprey wounding rates were above target levels in 2022 (3.15 A1 wounds per 100 Lake Trout) and were nearly double the 2021 rate. Lake Trout condition (predicted weight at length) was the highest since data collection began in 1983. Overall, the 2022 survey results indicate that adult Lake Trout are abundant and of high condition but composed mostly of hatchery-origin strains, suggesting recruitment of wild-produced offspring to the adult stock continues to be limited.