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A preliminary analysis of stable isotope data from satellite tagged humpback whales in the North Pacific
Liam E. Mueller-Brennan, Geraldine Busquets-Vass, Seth Newsome, and Daniel M. Palacios
From 1995-2019, Oregon State University conducted satellite tagging and tracking studies of humpback whales (Megaptera novaeangliae) at several locations in the North Pacific with the goal of describing their movement ecology across foraging grounds from the eastern Aleutian Islands to Southern California, and in the breeding ground of the Hawaiian Islands. A total of 189 skin biopsy samples were collected from tagged whales for stable isotope and genetic analyses. Preliminary results show (1) high isotopic niche width for samples collected in the Hawaiian breeding ground compared to the foraging grounds, indicating that this region is visited by a mix of whales from different foraging grounds; (2) there was little overlap in the niche width among several foraging grounds, indicating regional variation in prey preferences (e.g., trophic level) and/or differences in baseline isotopic values among foraging grounds; and (3) foraging grounds varied in niche width from low (northern Washington) to high (Oregon ? northern California), likely a reflection of the extent to which the whales remain within a limited foraging area. These results agree with satellite tagging data in terms of (1) the diversity of migratory routes to foraging grounds followed by animals tagged in Hawaii; and (2) regional differences in movement behavior and patterns of habitat use by whales tagged in the foraging grounds.
KEYWORDS: HUMPBACK WHALE; MOVEMENT ECOLOGY; FORAGING ECOLOGY; SATELLITE TAGGING; STABLE ISOTOPE ANALYSIS