Seasonal Movements and Habitats of Brown Trout (Salmo Trutta) in Southcentral Lake Ontario

During 1980–82 the movements, seasonal locations, and habitat preferences of brown trout in southcentral Lake Ontario were examined using radio telemetry and vertical gill nets. In fall and spring 85% of the 28 brown trout tracked by radio moved east from tagging sites. Movements frequently centered around original stocking sites, streams, and power plant outflows. Fish moved farther in spring (4.4 ± 2.5 km/d) than in fall (2.4 ± 1.7 km/d) seasons, but short-term movement rates did not differ between seasons (0.4 ±0.1 km/h in spring vs. 0.4 ± 0.3 km/h in fall). Females moved farther and faster than males in the fall. Brown trout generally occupied shallow waters < 1 km from shore; 81% of temperatures occupied by trout were between 8–18°C in spring (10.6 ± 2.3°C) and fall (10.1 ± 3.9°C), but turbidity appeared to influence presence or absence of trout near shore on a daily basis. In summer 78% of the 75 brown trout netted were in 8–18° C water (12.6 ± 4.0°C); 88% were caught in or within ±3 m of the thermocline region. Brown trout occupied regions near the thermocline despite widely varying bottom depths and thermocline temperatures. All brown trout were netted within 3.2 km of shore in summer, most in water ≤ 30 m deep; 70% were caught more than 3 m off bottom. The strong association of brown trout with nearshore and thermocline regions may distinguish their distributions from other salmonid species in Lake Ontario.