COSTA, D.P.; CROCKER, D.E; BOEHLERT, G; University of California, Santa Cruz; Sonoma State University ; Oregon State University: Foraging Behavior Of Northern Elephant Seals Relative To Frontal Features In The North Pacific Ocean

Archival data-loggers coupled with ARGOS based satellite tags are providing a detailed picture of the foraging behavior of elephant seals. They dive continuously, day and night, for the entire trip to sea that lasts between 2 to 8 months spending 90% of their time underwater, with dives averaging 20 minutes followed by surface intervals of less than 4 minutes. Modal dive depths are 300-600m with maximum dives exceeding 1500m! Male elephant seals depart A�o Nuevo rookery and travel rapidly and directly to foraging areas associated with the continental slope regions of the Aleutian Islands, Southeastern Alaska, Puget Sound and the Queen Charlotte Islands. In contrast, female elephant seals travel to foraging areas over the entire North Pacific. Our data indicate that males feed in specific locations associated with marked bathymetric features, whereas females apparently forage in areas associated with water column features such as oceanic currents or large eddies. In this study we examine the relationship between female foraging behavior and frontal systems. The behavior of female seals relative to large-scale frontal features was established by comparison of the ARGOS tracks of seals relative to satellite AVHRR images. A finer scale analysis of diving behavior relative to frontal features was carried out by correlation of dive behavior to water column temperature structure as determined from temperature sensors on the archival data loggers. Our results indicate that frontal features are an important feature in the foraging behavior of female elephant seals.