What’s the distinction between the long-finned and the short-finned pilot whale? Andrew Kitchener explains how the examination of the cranium of a stranded whale revealed the true identification of the species and probably the most northerly stranding of a short-finned pilot whale within the northeast Atlantic.
Pilot whales often happen in giant pods in deep water, migrating every year backwards and forwards alongside the sting of the continental shelf within the North Atlantic Ocean. So, when a pilot whale was seen within the Milford Haven space of Pembrokeshire, in west Wales in March 2012, it was definitely not in the suitable place. It was additionally clearly not effectively as a result of it was alone and liable to stranding, folks had been capable of method it carefully at sea and more often than not it was logging, resting on the floor and never shifting, so there have been issues about its well being and welfare.
Finally, the choice was made to humanely euthanase it in shallow water off Hazelbeach. Rob Deaville of the Cetacean Stranding Investigation Programme (CSIP) carried out a autopsy examination on the lifeless whale. He discovered that it had not fed for a while and had a average to extreme parasite burden in its stomachs and intestines. Rob collected the pinnacle of the pilot whale, which stayed in a freezer at CSIP’s base on the Institute of Zoology at ZSL London Zoo till it was donated to Nationwide Museums Scotland early final 12 months.
Pilot whales are giant dolphins that develop to greater than six metres lengthy. There are two species. The long-finned pilot whale happens generally in British waters and typically strands in giant numbers, whereas the short-finned pilot whale has by no means been recorded in British waters, however is present in hotter seas from the north of Spain southwards.
When the Hazlehead seashore pilot whale was examined, it was assumed that it was a long-finned pilot whale, like all of the earlier stranded pilot whales in Britain. In truth, the 2 species are fairly arduous to inform aside externally, particularly at sea. The pectoral fins are of various lengths as their names counsel, about one-fifth of physique size in long-finned pilot whales and one-sixth in short-finned pilot whales, however there’s some overlap in fin size.
The skulls are additionally comparable, however there are two key variations. Brief-finned pilot whales have fewer tooth and the anatomy of their rostrum or higher jaw is totally different to the long-finned pilot whale’s. When our curatorial preparator, Georg Hantke, had cleaned up the cranium, he might instantly see that this was not a standard long-finned pilot whale. By fastidiously inspecting the cranium, we had been capable of conclude that the Hazlehead seashore whale is Britain’s first short-finned pilot whale and probably the most northerly stranding of this species within the northeast Atlantic.
Whereas it’s excellent news that we’ve got one other cetacean species in Britain, it might even be unhealthy information, indicating that world local weather change is permitting one other warm-water species to maneuver into British seas and presumably out-compete resident cold-water species, such because the white-beaked and Atlantic white-sided dolphins.
During the last 30 years we’ve got recorded a number of new warm-water species in Scotland or Britain, together with striped dolphin, Blainville’s beaked whale, pygmy sperm whale, dwarf sperm whale, Fraser’s dolphin and now the short-finned pilot whale. The impression, if any, on resident species just isn’t clear, though there’s proof that white-beaked dolphin could also be shifting additional north.
Strandings schemes, reminiscent of CSIP in England and Wales, and the Scottish Marine Animal Strandings Scheme, are vitally essential in monitoring the patterns of strandings and the well being and welfare of untamed cetaceans round Britain. Nationwide Museums Scotland works carefully with each strandings schemes to make sure that there’s an archive of specimens which is freely out there for world analysis that helps the conservation and better understanding of the cetaceans within the northeast Atlantic Ocean.
