Meeting Abstract

P2.6  Jan. 5  Evidence of benthic foraging by northern elephant seals on North Pacific seamount and banks MAXWELL, SM*; ROBINSON, PW; SIMMONS, SE; COSTA, DP; University of California Santa Cruz; University of California Santa Cruz; University of California Santa Cruz; University of California Santa Cruz smaxwell@ucsc.edu

Northern elephant seals (Mirounga angustirostris) are capable of diving to depths exceeding 1600 meters, and are known to be both benthic and pelagic foragers. Most evidence of benthic foraging occurs along continental shelves, however researchers have speculated that seamounts and shallow banks may provide offshore benthic foraging grounds. Satellite tracks and dive profiles of three northern elephant seals in the North Pacific were analyzed to determine focal foraging areas near seamounts and banks. Two elephant seals tagged at San Benitos Island off the coast of Baja California Norte, Mexico in 2005 and 2006 showed dive profiles consistent with benthic foraging on Cortez Bank, a 60 km long bathymetric feature off southern California. The animals remained in the vicinity of the bank for approximately 91 days and 59 days respectively and benthic dive depths followed the depth profile of the shallow (to within six meters of the surface) bank. An additional animal tagged in 2005 at Ano Nuevo State Park near Santa Cruz CA showed both benthic and pelagic foraging behavior at a string of three seamounts beginning ~196 km east of Surveyor Seamount in the Gulf of Alaska and extending south east ~300 km. The animal foraged in the area for upwards of 14 days and showed repeated benthic dives to near depths of the seamounts (788, 344 and 287 meters). The 2006 San Benitos animal and the Ano Nuevo animal tracks were analyzed using first passage time and showed that the bank and seamount regions are focal foraging areas for these animals. Additional analysis of mass gain using drift dive profiles is ongoing to determine foraging success.