Satellite tagging, remote sensing, and autonomous vehicles reveal interactions between physiology and environment in a North Pacific top marine predator species
Noel Pelland1,2, Jeremy Sterling3, Alan Springer4, Sara Iverson5, Devin Johnson3, Mary-Anne Lea6, Nicholas A Bond7, Rolf Ream2, Craig Lee8 and Charles Eriksen1, (1)University of Washington, Seattle, WA, United States, (2)Alaska Fisheries Science Center, National Marine Mammal Laboratory, Seattle, WA, United States, (3)NOAA Alaska Fisheries Science Center, Marine Mammal Laboratory, Seattle, WA, United States, (4)University of Alaska-Fairbanks, Fairbanks, AK, United States, (5)Dalhousie University, Halifax, NS, Canada, (6)University of Tasmania, Hobart, Australia, (7)NOAA/PMEL/JISAO, Seattle, WA, United States, (8)University of Washington, Applied Physics Laboratory, Seattle, WA, United States
Abstract:
Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators' prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. This work describes recent publications and ongoing studies of northern fur seal (NFS) foraging ecology during their 8-month migration. Satellite-tracked movement and dive behavior in the North Pacific ocean was compared to remotely sensed data, atmospheric reanalysis, autonomous in situ ocean sampling, and animal borne temperature and salinity data. Integration of these data demonstrates how reproductive fitness, physiology, and environment shape NFS migratory patterns.
Seal mass correlates with dive ability and thus larger males exploit prey aggregating at the base of the winter mixed-layer depth in the Bering Sea and interior northern North Pacific Ocean. Smaller adult females migrate to the Gulf of Alaska and California Current ecosystems – where surface wind speeds decline, mixed-layer depths shoal, and coastal production is fueled by upwelling, coastal capes, and eddies – and less commonly to the Transitional Zone Chlorophyll Front, where fronts and eddies may concentrate prey. Surface wind speed and direction influence movement behavior of all age and size classes, though to a greater degree in the smaller pups and adult females than adult males. For naïve and physiologically less-capable pups, the timing and strength of autumn winds during migratory dispersal may play a role in shaping migratory routes and the environmental conditions faced by pups along these routes. In combination with other factors such as pup condition, this may play a role in interannual variations in overwinter survivorship.
