Long-Finned Pilot Whale | cornwallmammalgroup

Recognition:

long-finned pilot Whale-(Globicephala melas)

Order: Cetacea

The seas around Cornwall, and south west Britain, are one of the most heavily fished areas of the UK. Strandings of pilot whales around Cornwall have increased significantly since the mid-1970s, with seasonal peaks in strandings occurring between November and January. Stranded animals examined in Cornwall indicated that 61% of individuals had died due to bycatch in fishing gear. In 1911 about 50 pilot whales stranded at Penzance, mass strandings of this type are rare in the UK. A single animal stranded alive in Falmouth in 2013 and had to be euthanised because it was in such poor condition.

Cornish Tales

The long-finned pilot whale has a long, but robust, black body with a white chest patch tapering to a thin line that runs down to the genital slit. The tail stock is also noticeably deep.

Younger animals are more slender and paler. When fully grown, males may reach more than 6 m in length and weigh up to
3.5 tonnes, females may reach 5 m. The bulbous head is rounded with a large melon (forehead) and no protruding beak. The mouth contains 9 to 12 pairs of peg-like teeth. As might be expected from its name, the tapered pectoral fins are particularly long: they can be up to a quarter of the body

length, and they are well swept back. The male’s fins are proportionally longer than those of the female. The dorsal fin is low, and located about one third of the way back from the head. In females and immature animals the fin is sickle-shaped while in adult males it is broad and humped. In older animals the fin becomes more rounded and less dolphin-like. Sometimes there is a greyish white ‘saddle’ patch just behind the dorsal fin, but this is not always present in animals in the Northern Hemisphere. In the North Atlantic about half of adult males have a thin pale stripe behind the dorsal fin. About 20% of animals, mainly males, also have a pale eye blaze.

Ecology and behaviour

Long-finned pilot whales are a pelagic species preferring the waters over the continental shelf and slope, where they can make deep foraging dives. However, some populations make a seasonal movement inshore during the summer months.

The mouth of the long-finned pilot whale is adapted for hunting soft-bodied prey, specifically squid, but they also take fish when available. They dive to depths of more than 500 m to forage, but some food species migrate towards the surface at night, so they hunt more after dark, when prey is closer to the surface. The breeding season for this species appears to be mainly April to September. Pregnancy lasts about a year and the newborn calves are around 2 m long, weighing 75 kg. They are suckled for up to two years, so a female probably gives birth only once every 3 to 5 years. Life expectancy in this species is thought to be between 50 and 60 years, with females often living longer than males. The species is highly social and gregarious. Pods can sometimes number into the hundreds.

Whalers in the 18th and 19th century sometimes targeted this species. More recently they have been subjected to drive fisheries, historically in North America, Ireland, Orkney and Shetland, where entire pods are herded into the shallow bays and stranded intentionally, allowing the hunters to kill the whales with ease. This practice is still carried out in Japan and the Faroe Islands. In the Faroe Islands, annual catches ranged from 1500 animals in the 1970s, to 2500 in the 1980s and then 1500 again in the 1990s. Fishing gear entanglement is also a serious problem
worldwide, with trawls, gillnets and longlines all causing mortalities.

Survey Methods:

As a seasonal offshore species, land-based surveying for long-finned pilot whales is largely unproductive in the UK. Boat-based surveys from ships of opportunity, such as ferries and cargo ships that cross areas of open ocean, are more effective. This is currently in regular operation on many vessels from the UK using staff and volunteers from Organisation Cetacea (ORCA) and Marinelife.

Distribution:

Sighted fairly frequently around Cornwall until the 1980s. More recently only very occasionally reported from our coastline. Occasionally seen around Britain, mainly in north west Scotland.
The North Atlantic population ranges from Greenland and the north east USA, to north Africa and the Eastern Mediterranean.

Records:

2007-2012: 11

2002-2007: 60

Pre-2001: 423

Total: 494

Did you know?:

This whale is well known for live strandings of large groups, particularly in New Zealand and Australia. A debilitated or disorientated lead animal, often a female, becomes beached and the strong social bonds of the pod result in the whole group being stranded. Other causes of strandings may include sonar activity and marine disturbance. In the UK there were three stranding events in 2010 and 2011, all in
the north of Scotland and the Hebrides.

Conservation:

Two distinct and separated populations, or even subspecies, are recognised – the North Atlantic population and the Southern Ocean population. The North Atlantic population is thought to number in the hundreds of thousands, while around 200,000 are estimated for the Southern Ocean population. They are generally regarded as common. In the UK they are protected by the Wildlife and Countryside Act 1981 from intentional harm and disturbance, while international agreements and conventions aim to research the distribution and ecological needs of the species in more depth so that any threats to the survival of the population can be identified and reduced or eliminated where possible.