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A recent survey of the Scotia Sea in the Southern Ocean has provided fresh evidence for the importance of this region for poorly known members of the beaked whale family.
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Cetacean researcher Dylan Walker recently completed a survey of the region on behalf of ORCA. The survey, which took place onboard the cruise vessel MS Andrea between 30 January and 15 February, covered parts of the Southern Ocean between Argentina, the Antarctic Peninsula and South Georgia. Despite being an increasingly popular destination for cruise vessels, dedicated surveys of the Southern Ocean in the region of the Drake Passage and the Scotia Sea are still limited and data on the distribution of cetaceans is consequently sparse. |
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The Southern Ocean is also home to the roughest seas on Earth. Even in the summer months, frequent low pressure systems move westwards at pace, whipping up storms as they go. As a result, the possibilities for surveying any cetaceans, let alone illusive beaked whales, is limited.
However, on the 6th and 7th February whilst travelling between Elephant Island on the western edge of the Shetland Islands, and South Georgia, unusually calm conditions prevailed with a sea state of one and a swell of less than two metres. |
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The first beaked whales were encountered at 8.25 on 6th February when two Southern Bottlenose Whales passed by on the port side of the ship giving prolonged views. Their steep, bulbous foreheads were striking as the animals surfaced and their blows were clearly visible. The whales, possibly mature females due to a lack of pale markings or scarring, were over a seamount rising to 2080m from a depth of 3610m on the surrounding sea floor, just to the north of the Hesperides Trough. There were no further sightings of beaked whales or other cetaceans until the following day, the 7th February, approximately half way between the South Shetland Islands and South Georgia.
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At 11.48 a lone Southern Bottlenose Whale appeared close in front of the ship. It was uniform in colour and again showed the clear bulbous forehead.
Almost two hours later, at 14:33 an unidentified whale appeared on the starboard side at a distance of 500m. It was logging and blowing regularly. The blow was large, angled at 45 degrees and the animal appeared to be completely white. Initial impressions were that it was a white Sperm Whale but as it rolled forward it revealed a small fin two-thirds of the way along the back. |
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At that moment a near-identical animal appeared ahead of the ship and was soon identified as another Southern Bottlenose Whale. It too, appeared almost white underwater, recalling a Risso´s Dolphin. The animal was swimming with the ship and passed very close, allowing photographs to be taken of its scarred and strangely patterned back and head. The dorsal fin was tall and prominent with a large nick towards the base. Both animals were therefore recorded as Southern Bottlenose Whales, and although teeth were not observed, it seems likely that they were males. |
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Finally, at 15:25, two small whales were observed swimming towards the bow at an angle. Although the beaks were barely raised, they appeared of médium-length and white. The forehead was also white. On closer inspection of one individual, the head was dark but there was a broad pale swathe on the back reaching as far back as the dorsal fin. Behind the dorsal fin the back appeared chocolate-brown to black in colouration. The animals moved leisurely, surfacing 10 – 12 times. Consultation with the field guide was made only after extensive notes and drawings were taken, confirming that the animals were Strap-toothed Whales. |
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Dylan told ORCA: “The survey was a big success in terms of the number of beaked whales sighted, which really took us by surprise. Although we must be cautious about drawing conclusions from just one survey, the variation in sea floor depth combined with the high productivity created by the presence of the Antarctic Convergence in this area certainly suggest that it could be of importance for this rarely sighted family of cetaceans.”
Further evidence of the presence of both Southern Bottlenose Whales and Strap-toothed Whales in the region comes from the Museum at Grytviken, South Georgia, which displays skulls of both species.
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Dylan
Walker / Breathtakingwhales.com
If you have beaked whale sightings information then we would like to hear from you. For more information, browse at www.beakedwhaleresource.com
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