High prevalence of basin fidelity and homing by lake trout (Salvelinus namaycush) in a small northern lake

Identifying how habitat structure influences the spatiotemporal movements of fishes is important for conservation, population assessment, and management purposes. Here, we determined whether acoustically tagged lake trout (Salvelinus namaycush) from a 305 ha lake exhibited homing behaviour and lake basin fidelity over multiple seasons and years. The lake has two distinct deep basins (north and south) connected by a shallower centre basin. Fifteen lake trout captured during the spawning season from both deep basins were tagged and released in the south basin. All translocated north-basin fish quickly returned to the north basin (median = 1.85 days, range = 0.36-4.5 days), apart from one fish that returned 41 days post-release, while none from the south ventured into the north basin during this time. After translocated individuals returned, all fish demonstrated high basin fidelity among years, as >90% of detections were from the same basin fish were captured, while <0.7% (by three fish) were from the opposite deep basin and <9% from the centre basin. The probability a fish was detected outside its basin of capture was highest in winter (15.9%) and fall (14.3%) and lowest in summer (0.41%).