Sperm Whale: Physeter macrocephalus
IUCN status: Vulnerable
Status and distribution summary:
Occurs in most deep water areas of the world. Females migrate from calving grounds in tropical waters such as the Cape Verde Islands to summer in temperate waters including Biscay where many of the sightings are of family groups, suggesting that the Bay is used as a nursery area. Only solitary males visit high latitudes.
Sperm Whales hunt at great depth for large squid and deep water fish, favour the continental shelf slopes and seamounts usually over 1,000m depth.
Hunted since the 1700s, and was once one of the most abundant of the large whales (with a modelled population in excess of 1.1million), 770,000 were killed between 1940 and 1960 alone. Although there is no accurate assessment of the current global population there has some recovery from the scale of exploitation, but reproduction rates are low.
Other threats: Sperm Whales are known to carry high levels of chemical contaminants that may affect immunosuppression and reproduction.
Where it is seen:
Southern Bay of Biscay, over canyons and deep water areas.
Frequency of sightings:
Varies from year to year; virtually unseen in some years but regular in others with sometimes over 20 seen in a crossing. Usually recorded in late summer and early autumn, either as singles or in family groups of 2-5, and occasionally in larger groups, presumably associated with good feeding.
Large, bulls up to 20m in length, but females rarely exceed 12m. With a huge blunt head
In regular surfacing they usually show the following features:
- Grey or brown upper parts, which depending on light conditions can vary in appearance from black to pale orangey brown.
- There is no dorsal fin, but has a large 'knobble', with other smaller ones down the dorsal ridge of the tail stock.
- Strong blow is angled forward from a single blow hole set right at the front of the head and angled to the left.
Dives for long durations, up to 2 hours.
Between dives often stays on the surface, breathing every 10 -20 seconds, travelling only slowly and resembling a large piece of driftwood.
Deep dives, at the end of breathing sequences, are characterised by a strong arch of the tail stock, vertical lifting of the flukes, and the whale slow dives.
Sperm Whales, particularly immatures, breach regularly, emerging at a steep angle and sometimes leaping clear of the water, before belly flopping back into the water.
The steeply forward angled blow and lack of dorsal fin should avoid confusion with other species.