Sowerby's Beaked Whale

Sowerby's Beaked Whale: Mesoplodon bidens

IUCN Status: Data deficient

Status and distribution summary:

Relatively small global range, limited to the northern Atlantic Ocean from the Azores north to the ice edge. No reliable population estimates have been made of Sowerby's Beaked Whale, but it is not thought to be common in any part of its range.

Exploitation: not known to be hunted.

Other threats:

As with all beaked whales, is vulnerable to loud under-sea noise from military sonar or seismic survey. Known to have died following ingestion of plastic bags, which could be a significant issue.

Where it is seen:

Over deep waters in southern Bay of Biscay, particularly the major canyons.

Frequency of sightings:

Rarely seen from larger ships, though it may be under-recorded as it is often undemonstrative. Small boat surveys of seamounts have had better results.

Recognition:

Small to medium sized (5-7m). Significantly smaller and less bulky than Cuvier's beaked whale.

Dark grey upper parts with some blotching and single gouge scarring in males (acquired during dominance fights - males have a pair of quite large erupted teeth on the mid-jawline).

Small dolphin like dorsal fin set 2/3 back to the tail.

Has a long thin beak and bulging melon (forehead and crown), with a distinct notch behind the melon where the blow hole is situated. In adult males two small teeth are visible at mid point of beak, though  not a good feature unless seen very well.

Behaviour:

Little known. Often seen in small groups (2-5 reported). Thought to spend only a short time at the surface, taking 4 or 5 breaths in 1 or 2 minutes before deep diving for approximately 15 minutes.

Head often breaks surface when surfacing, and the elongated beak and melon shape are strong aids to identification. A small bushy blow is sometimes visible.

Confusion species:

Other mesoplodon Beaked Whales look very similar, though with good views the head shape is distinctive.