Habitat selection by foraging northern fur seals: assessing in-situ ocean temperature and links to Oceanographic features

• Main Author: Chad Andrew Nordstrom
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Bering Sea; Callorhinus ursinus
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.662.6136; http://www.marinemammal.org/wp-content/pdfs/ubc_2012_fall_nordstrom_chad.pdf

ii Habitat characteristics and mechanisms that enable predators to successfully forage are poorly understood in open marine ecosystems. I addressed this problem in the eastern Bering Sea using animal-born data-loggers carried by lactating northern fur seals (Callorhinus ursinus) from two populations breeding in distinct oceanographic zones — a declining population on St. Paul Island on the continental shelf, and an increasing population on Bogoslof Island over the oceanic basin. The data-loggers recorded water temperatures, dive depths and animal locations throughout foraging trips that lasted as long as 17 days and extended as far as 460 km from the islands. I contrasted tag-derived ocean temperatures with concurrent shipboard measurements and found that the fur seal data revealed finer-scale hydrographic processes with less estimated error than ship-derived data, particularly in dynamic oceanographic areas. I also identified probable foraging hotspots using first-passage time analysis of at-sea locations of individual females, and linked them to fine-scale hydrographic data using habitat selection models. I found that hot spots were related to thermoclines and surface fronts (although not with water