Seasonal distribution of sperm whales (Physeter macrocephalus) around Kelvin Seamount

No abstracts are to be cited without prior reference to the author.

Sperm whales (Physeter macrocephalus) are widely distributed in all oceans, but they are clumped geographically, generally in areas associated with high primary and secondary productivity. The warm, clear waters of the Sargasso Sea are traditionally thought be low in productivity, however recent surveys have found large numbers of sperm whales there. The New England Seamount Chain bisects the north-western portion of the Sargasso Sea, and might influence the mesoscale eddies associated with the Gulf Stream, thus creating areas of higher productivity within the Sargasso Sea. We investigated the seasonal occurrence of sperm whales over Kelvin Seamount and how it is influenced by oceanographic variables. An automous recording device was deployed over Kelvin Seamount (part of the New England Seamount Chain) from May to June 2006 and November 2006 to June 2007. Hourly two-minute recordings were examined for the presence of sperm whale echolocation clicks. Sperm whale prevalence varied seasonally and with respect to Gulf Stream characteristics. Sperm whales were more prevalent around Kelvin in the spring (April to June: mean = 46% of recordings contained clicks) compared to the winter (November to March: mean = 16% of recordings contained clicks). Sperm whale prevalence at Kelvin was related to distance to Gulf Stream, presence of rings and/or meanders and position relative to the Gulf Stream but independent of ocean temperature. The interaction between the Gulf Stream and New England Seamount Chain may play an important role in sperm whale occurrence in this area.