Sergio, Ava2026-04-142026-04-142026-04-08https://hdl.handle.net/10222/85968The wild Critically Endangered Atlantic whitefish (Coregonus huntsmani) population persists in just one watershed on Earth, the Petite Rivière in Nova Scotia, Canada. The species' rarity has resulted in limited knowledge regarding the habitat use of Atlantic whitefish. The primary threats to Atlantic whitefish are predation by and competition for resources with invasive chain pickerel (Esox niger) and smallmouth bass (Micropterus dolomieu). To inform the effective implementation of the Atlantic whitefish recovery strategy, this thesis evaluates the movement ecology of hatchery-reared Atlantic whitefish alongside that of co-occurring invasive predators in one of the three lakes native to Atlantic whitefish. Using acoustic telemetry, Chapter 2 assessed the general and fine-scale habitat use of Atlantic whitefish in Milipsigate Lake, Petite Rivière watershed. Atlantic whitefish did not exhibit seasonally distinct changes in habitat use and were broadly spatially distributed across the lake. Highest predicted counts of individuals occurred in the lake centre and western shorelines, and the fish exhibited a positive relative selection strength for areas of the lake with intermediate bathymetries. Chapter 3 compared the seasonal changes in space and depth use of chain pickerel and smallmouth bass in the same lake using acoustic telemetry. Pronounced seasonal differences in space and depth use occurred for both species that were largely non-overlapping. The contrasting habitat use of the two co-occurring invasive predators indicated that their combined spatial coverage of the lake is extensive. Overall, these findings demonstrate the current disconnect between hatchery production and ecological acclimatization of Atlantic whitefish post-release, while also identifying opportunities to refine rearing strategies. These findings also highlight the likelihood of spatial overlap between both invasive species and Atlantic whitefish, and the potential negative ecological implications for Atlantic whitefish and the native food web in the Petite Rivière watershed. Knowledge gained from this thesis demonstrates the versatility and utility of fine-scale positioning and spatial modelling for generating critical knowledge for rare aquatic species and improving invasive species management. Collectively, these findings provide an evidence-based foundation for recovery actions and targeted invasive species management to prevent the wild extinction of one of Canada’s most endangered fishes.enAcoustic telemetryHabitat useResource selection functionGeneralized additive modelConservation