Ocean-entry timing and marine habitat-use of Canadian Dolly Varden: Dispersal among conservation, hydrocarbon exploration, and shipping areas in the Beaufort Sea

Conservation and management of anadromous salmonids are enhanced by understanding timing, spatial extent, and occupied depths and temperatures in marine feeding habitats. We examined ocean-entry timing and marine habitat-use, and their association with environmental conditions (e.g., sea-ice and sea-surface temperatures (SSTs)) of anadromous Dolly Varden (Salvelinus malma malma) from the Canadian Arctic using pop-up satellite archival tags (PSAT) and data storage tags. Using this information, we evaluated the extent tagged fish occupied offshore (>5 km) habitats, and their proximity to a marine protected area (MPA) and areas of potential threats in the Canadian Beaufort Sea. Ocean-entry by tagged fish using the western Mackenzie Delta for freshwater migration occurred approximately mid-June (range = 8–26 June) and closely followed landfast sea-ice break-up based on satellite imagery. While at sea, fish predominately occupied surface waters (