Movement and diet of humpback whales (Megaptera novaeangliae) in relation to capelin (Mallotus villosus) off the east coast of Newfoundland

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Johnson, Kelsey
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Knowledge of critical foraging areas in time and space, of large marine predators are important to inform management plans. An important foraging ground for humpback whales is coastal Newfoundland. The goal of this study was to investigate the foraging movements and site fidelity of humpback whales, as well as diet in relation to their primary prey, capelin, on their summer foraging grounds off the east coast of Newfoundland. I determined that humpback whale movement patterns within their Newfoundland foraging grounds were associated with the availability of capelin. At the regional scale, humpback whales were consistently abundant within bays when capelin was present. At bay scale, humpback whale presence was influenced by the timing of spawning, rather than capelin shoal characteristics, and individual humpback whales returned to a small area (10 km2) centered on a cluster of capelin deep-water spawning sites. Using stable isotope analysis, I found minimal dietary niche overlap between years (9%). These differences, were driven by inter-annual variation in prey 13C values and, thus, diet reconstruction resulted in capelin/herring comprising > 90% of humpback whale diet in both years. Together, our findings suggest that persistent capelin deep-water spawning sites may be important foraging areas for humpback whales in coastal Newfoundland.
Ecology, Marine, Humpback whale, Stable isotope analysis, Foraging ecology