Mesoplodon bidens
Sowerby's beaked whale

Sowerby's beaked whales are found in temperate to sub arctic waters in the eastern and western North Atlantic. They are found around the British Isles and are known to occur from Newfoundland to Massachusetts. Sowerby's beaked whales occur as far north as Labrador in the west and in the Norwegian Sea in the east, southern limit is thought to be somewhere between 33ºN and 41ºN. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006b; Barrett and Macdonald, 1993; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003; Ruff and Wilson, 1999)

Sowerby's beaked whales are found in cool to warm temperate offshore waters of the North Atlantic Ocean. They are usually observed in open water and most often seen in areas were depths range from 198 to 1524 m. (Carwardine, 2002; Clapham et al., 2002; Mottet, 2003)

Mesoplodon bidens is bluish grey to slate grey in color, with a lighter underside, grey and white spots may be present on the body with limited scaring. Mesoplodon bidens have a long slender beak that contains a pair of teeth midway up the lower jaw. They have a long think body, long flippers for the Mesoplodon family, and no notch in the fluke. The dorsal fin is quite small with a rounded tip and may appear falcate. Young M. bidens have a light blusih grey to white underside, more prominant than in adults. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006a; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003)

The is no data on the lifespan in M. bidens. ("MarineBio.org", 2006; Barrett and Macdonald, 1993; Carwardine, 2002; Clapham et al., 2002)

When surfacing, Sowerby's beaked whales have been observed coming up at a steep angle with the head breaking the surface first. They then take a series of quick breaths (about 4 to 6) over a period of a minute. After a minute at the surface they take a longer dive for about ten to fifteen minutes, and may resurface up to 800 meters away. They have been recorded to dive up to 28 minutes. The blows of M. bidens are usually invisible or fairly inconspicuous. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006a; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003)

Sowerby's beaked whales are social animals, most often observed in pairs. Occasionally they are seen in pods ranging from 3 to 10 individuals. Sowerby's beaked whales stay clear of boats, so sightings are rare and most observations of these whales are from strandings. Sowerby's beaked whales often strand in pairs; sometimes as many as six individuals will stand together. They are the most commonly stranded species in the genus Mesoplodon. There are records of M. bidens strandings year round, except for the month of February. The highest density of strandings appears to occur between the months of July and September. (Barrett and Macdonald, 1993; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003)

Home Range

There is no information on the home range of M. bidens.

A young animal, that was kept in a dolphinarium for a few hours, was recorded using high frequency sound pulses to echolocate. (Barrett and Macdonald, 1993)

The diet of Sowerby's beaked whales consists mostly of squid, octopus, and fish. A necropsy of one individual showed stomach contents that included bottom-dwelling and deep water fish. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006a; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003)

There is no information about predation on Sowerby's beaked whales. Once they reach their adult size it is likely that they are protected from much predation. Killer whales and large sharks may target Sowerby's beaked whales. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006b; Barrett and Macdonald, 1993; Carwardine, 2002; Clapham et al., 2002; Culik, 2003; Mottet, 2003; Ruff and Wilson, 1999)

Little is known about the role of Sowerby's beaked whales in the northern Atlantic ecosystem. They are undoubtedly predators of marine organisms. ("MarineBio.org", 2006; Carwardine, 2002; Clapham et al., 2002)

Sowerby's beaked whales are occasionally caught in fishing gear, damaging nets in the process. Arguably this is more traumatic for the whales than fishing crews. (Clapham et al., 2002; Culik, 2003)

Sowerby's beaked whales were once infrequently harvested by Norwegian whalers. They are no longer hunted actively. (Clapham et al., 2002)

There is very little data on Sowerby's beaked whales. As a result there is little information on population sizes, current or historic, to determine conservation status. This species is rarely seen in the open ocean, most records are from strandings. ("MarineBio.org", 2006; Barrett and Macdonald, 1993; Carwardine, 2002; Clapham et al., 2002; Ruff and Wilson, 1999)

As with all beaked whales (Ziphiidae) there is very little data on M. bidens. This species was the first of the beaked whales to be described. It was described by John Sowerby in 1804. ("MarineBio.org", 2006; "Whale and Dolphin Conservation Society", 2006a; Carwardine, 2002; Clapham et al., 2002)