Abstract:
We describe the habitat use of 22 male southern elephant seals (Mirounga leonina) satellite
tagged at Marion Island between 2004 and 2008. While a few areas of increased utilization appeared to be
associated with areas of shallower bathymetry (such as sea-floor ridges and fracture zones), seals in our
study did not target other areas of shallow bathymetry within close proximity to Marion Island. Rather,
most elephant seals foraged pelagically over very deep water where much variation was evident in diel
vertical migration strategies. These strategies resulted in generally deeper and longer dives than what has
been reported for male elephant seals from other colonies. No significant differences were recorded for dive
durations or dive depths between adults and sub-adults. However, younger animals displayed a positive
relationship between dive durations and age, as well as between dive depths and age, while these
relationships became negative for older animals. Mixed model outputs suggested that seals increased their
aerobic fitness as migrations progressed, enabling them to undertake longer dives. We conclude that Marion
Island male elephant seals exhibit much variability in dive strategy and are seemingly capable of exploiting
a range of different prey types occurring in various depth layers.
