Limited sexual segregation in depth use by southern elephant seals from Marion Island

• Main Authors: McIntyre, Trevor, Ansorge, I. J., Bester, M. N., Bornemann, Horst, Plötz, Joachim, Tosh, C. A.
• Format: Conference Object
• Language: unknown
• Published: 2009
• Subjects: Elephant Seals; Marion Island; Southern Elephant Seals
• Online Access: https://epic.awi.de/id/eprint/20914/; https://epic.awi.de/id/eprint/20914/1/McI2009b.pdf; https://hdl.handle.net/10013/epic.33214; https://hdl.handle.net/10013/epic.33214.d001

Based on body size dimorphism, southern elephant seals from Marion Island were expected to display significant differences betweensexes in depth use while at sea. We instrumented 53 adult and sub-adult animals of both sexes with satellite-relay data loggers(SMRU) between 2004 and 2008. These devices transmitted basic dive data, as well as location and temperature data while theinstrumented animals were at sea. Using a simple calculation, we determined time spent by individual animals in various depthcategories during a total of 182 882 dives. Animals of both sexes targeted depths between 300m and 600m more than other depthcategories, and substantial overlap between sexes was recorded for time spent in depths between 500m and 600m. Male elephantseals however targeted and spent significantly more time in depths between 600m and 1250m (p < 0.05). Female elephant sealstargeted and spent significantly more time in depths between 200m and 500m (p < 0.05). No significant differences were recorded fordepth use between adult and sub-adult males. The overlap in mid-water depth use by both sexes suggests that the limited segregationobserved in depth use by southern elephant seals from Marion Island is likely driven by different physiological capabilities, and notforage selection or predator avoidance.