Site fidelity during spawning period of a population of stocked fish

Understanding site fidelity of a species provides insights into preferences and locations of key habitats associated with spawning, foraging, and other life-history events. For compromised species with high spawning site fidelity and where habitat quality impedes recruitment, insights into their behavioural variability may be useful for management. Here, we examined the relative intra-population variation in site fidelity for lake trout ( Salvelinus namaycush) from eastern Lake Ontario during the spawning period, a population largely composed of stocked fish. Using a 5-year dataset, we created an acoustic telemetry-specific site fidelity index. All tagged fish ( n = 72) returned to the general spawning area every year, but individuals showed varying fidelity to specific sites. Low fidelity was observed for 51.4% of individuals, compared to 27.8% and 20.8% showing medium and high, respectively. All females had low or medium fidelity compared to half of the males, demonstrating gender-based differences in fidelity. This study provides quantitative evidence that lake trout can display strong general spawning fidelity at larger (i.e., ecosystem) scales but moderate levels of behavioural variability and potential plasticity on smaller, regional scales (i.e., for specific sites) in freshwater ecosystems.