True's Beaked Whale: Mesoplodon mirus
IUCN Status: Data deficient
Status and distribution summary:
Very poorly known. Two populations known, one in the North Atlantic including Biscay, the Azores, Canaries, Bahamas and Nova Scotia; the other from eastern South America east to Australia. These are likely to be isolated and so may be genetically distinct.
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, from 430-460 N.
Frequency of sightings:
Only recorded from ferries on 3 occasions.
Small to medium sized (c5m). Significantly smaller and less bulky than Cuvier's beaked whale.
- Potentially variable paleage
- Grey blue upper parts with some minor but diagnostic parallel gouge scarring in males (acquired during dominance fights - males have a pair of narrow set teeth at the tip of the lower mandible).
- Small triangular slightly falcate dorsal fin set 2/3 back to the tail.
- A medium length beak that smoothly blends to the small melon, with a slight notch 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.
Little known. Recorded singly and in pairs in Biscay. Breaches.
- Other mesoplodon Beaked Whales look very similar, and great care is needed in separating them. Photographs are probably essential.
- Gervais' Beaked Whale is the closest in appearance that occurs in the North Atlantic.