Marine mammal experts were alerted to the shores of SW Anglesey, North Wales, today to rescue a live-stranded “harbour porpoise”. When rescuers arrived at the scene the animal was a little different than expected for this widespread species and photographs from the volunteers soon made it back to the headquarters of Sea Watch Foundation.
Sea Watch volunteer, Ben Murcott, was the first to arrive at the vast Newborough beach on Anglesey and soon realised that the animal was much more unusual than expected. Ben was one of the trained British Divers Marine Life Rescue (BDMLR) volunteers on the scene which meant that they were able to assist the animal back into the water in the hope that it would survive the stranding. Another volunteer took photographs as the team (which included Rhosneigr and Bangor Coastguard) helped the animal to re-float which showed clearly that it was in fact a Kogia whale, of which there are two species, pygmy sperm whale and dwarf sperm whale.
Further measurements and observations were needed before Sea Watch could confirm which of the two species it was.
The only previous sighting of dwarf sperm whale was on October 11th 2011 when Dr Peter Evans, Director of Sea Watch, was able to confirm the species from photos taken in Mounts Bay next to the Cornish town of Penzance. That animal was also initially misidentified as harbour porpoise.
“Dwarf sperm whales are tropical species, occurring in the Atlantic off the West African coast whereas pygmy sperm whales normally range further northwards as far as the Bay of Biscay. There are only seven previous records of dwarf sperm whale in all of Europe and although pygmy sperm whale has been recorded more often, there are still only about a dozen records from the UK, and only one previous one from Wales” says Dr Evans.
The confirmation of the first dwarf sperm whale in Cornwall in 2011 meant that 29 species of cetaceans had now been recorded in UK and Irish waters in total. “Along with pygmy sperm whales, these represent an increasing number of records of warm water species to be turning up around the British Isles in recent years. These include Cuvier’s beaked whale, Blainville’s beaked whale and striped dolphin,” continues Dr Evans.
So little is known about both the dwarf sperm whale, Kogia sima and pygmy sperm whale Kogia breviceps that they are listed as ‘data deficient’ on the IUCN Red List of Threatened Species, However, some scientists suggest their scarcity may have been due to extensive hunting in the past.
Dr Evans explains: “Pygmy and dwarf sperm whales are very difficult to tell apart, but the dwarf sperm whale has a much larger dorsal fin, which can be very variable in shape whereas the pygmy sperm whale always has a small falcate fin. The fin of pygmy sperm whale is also set further back that in dwarf sperm whale where it is more or less centrally placed.
STOP PRESS (18:00h) PYGMY SPERM WHALE CONFIRMED: “The latest picture sent through (see below) most closely resembles pygmy sperm whale”, says Dr Evans.
Known as separate species since only 1966, the dwarf and pygmy sperm whales are almost indistinguishable in the field. The animals are little more than the size of a harbour porpoise and easily mistaken for such. The Kogia whales appear similar to dolphins but are slower and their head is squarer. There is a light mark between the eye and the flippers (named a false gill) which gives the head a shark-like appearance. They also show similarities to beaked whales but are smaller. In the pygmy sperm whale the dorsal fin is smaller compared to the body size and set further back than in the dwarf sperm whale. There are also slight differences in their dentition: the pygmy sperm whale usually has 12-16 teeth in the lower jaw whereas, the dwarf sperm whale usually has 7-12 teeth. There are also some skull differences which can be noted upon post mortem.
The fate of the Anglesey whale is still in the balance, the team from BDMLR, Sea Watch and the UK Cetacean Strandings Investigation Programme have done their best to rehabilitate the disorientated animal and now have to hope it doesn’t strand once more.
Should anyone find this or another live stranded animal they should call the BDMLR hotline on 07787 433412. Should anyone find a stranded animal which is already dead they should report it to the Cetacean Strandings Investigation Programme website (http://ukstrandings.org/how-to-report-a-stranding/).