Ecology and timing of black bass spawning in Lake Ontario and the St. Lawrence River: Potential interactions with the angling season

Abstract The timing of spawning for largemouth bass and smallmouth bass in Lake Ontario and the St. Lawrence River was examined over a 3-year period. Temperatures were warmer in the preferred spawning habitat of largemouth bass, and the majority of nests had offspring that had reached the swim-up stage at the opening of the bass angling season in 2 of the 3 years examined. In contrast, the proportion of smallmouth bass nests that had reached the swim-up stage when the bass angling season opened ranged from 4 to 13% during these years. Using models created from nest observations and temperature data, we provide estimates of the additional time required to allow higher percentages (20%, 50% and 80%) of smallmouth bass nests to reach the swim-up stage. Invasive round goby, which are an important nest predator, were more abundant in the spawning habitat preferred by smallmouth bass. A simulated angling experiment showed that round gobies invaded about half of the nests when the guarding male was briefly angled and released. In view of these results, it may be important to re-evaluate the dates for the closed season in order to maintain the quality of the bass fisheries in Lake Ontario and the St. Lawrence River.