Hebridean Whale and Dolphin Trust 2011 sightings and strandings summary

23/02/2012 18:09:40

Sightings

The Hebridean Whale and Dolphin Trust (HWDT) had another successful research season in 2011 and we couldn't have done it without the support of the public - massive thanks to all those who reported their sightings.

Sightings reported via the Community Sightings Network in 2011 increased in comparison to 2010 reports; in total 696 were reported to HWDT (482 in 2010). Harbour porpoises were the most regularly sighted cetacean species, although this isn't surprising as Hebridean waters host one of the highest densities of this species in Europe!

Species reported:

Harbour porpoise - 299	Pilot whale - 3
Bottlenose dolphin - 109	Atlantic white-sided dolphin - 2
Minke whale – 100	Atlantic grey seal – 1
Basking shark – 82	Fin whale – 1
Common dolphin - 71	Humpback whale – 1
Killer whale - 22	Bottlenose whale – 2
Risso’s dolphin - 12	Sperm whale – 1
Sunfish - 8	Sei whale – 1
Unknown species – 7	Turtle – 1
Unknown baleen whale – 5	White-beaked dolphin - 0

 

After the Harbour porpoise the most frequently reported species were the Bottlenose dolphin, Minke whale and Basking shark. These three species are targets for photo identification and HWDT are very grateful for those members of the public who, as well as reporting sightings, also manage to get identification shots. Although over 80 sightings of Basking shark were reported to us, the number of Basking sharks reported was much lower when compared to 2010. This follows suit with the rest of the UK and marine biologists suggest that, rather than there being fewer Basking sharks, it is more likely that the cooler, unsettled conditions inhibited the stratification of the water column resulting in plankton being found deeper in the water column. If Basking sharks are foraging at depths they are less observable than when ‘Basking' at the surface.

Leatherback turtle, Humpback & Sperm whales
Notable sightings during 2011 included a leatherback turtle and a Sperm whale. The Leatherback turtle was spotted by volunteers onboard Silurian in mid-June whilst crossing the Minch one day. Skipper Dave Hanna said that "It was the most exciting moment of my life". This sighting (and quote) even made it onto the BBC news much to Skipper Dave's delight! The Sperm whale was sighted off Mull in early September in the Sound of Raasay and prompted much concern regarding a severe dent behind its blowhole. Read about the Leatherback turtle seen off Scotland

Strandings

Seventeen strandings were reported to HWDT in 2011. The results from the post-mortems of individuals where samples were taken by HWDT are still pending but will be announced on our website in due course.

70 Pilot whales
On July 22nd around 70 pilot whales were reported at risk of stranding at Kyle of Durness. In one of Scotland's biggest mass stranding events, trained medics battled against the tide and the weather to rescue as many individuals as possible. Without the assistance of trained medics many more pilot whales at Durness would have perished. Training courses are available to all members of the public to gain the fundamental techniques to assist in marine mammal strandings. If you are interested in attending one of these courses or you find a stranded cetacean please click here.

Blue fin & Albacore tuna
In September a blue fin tuna was reported to HWDT by a member of the public! Although bluefin tuna are rare in Scottish waters their presence is not unprecedented. Remarkably, another tuna species was reported just a few weeks later at Lochinver. This time the species was identified as an Albacore tuna, a typically oceanic and Mediterranean Sea fish that is more commonly found in the southerly latitudes of the British Isles. These two records are the first for HWDT and we are keen to hear about any other tuna sightings/strandings you may have.

Pygmy sperm whale
In October, a pygmy Sperm whale was reported stranded at Easdale. Pygmy Sperm whales are rarely sighted and identified alive at sea, and therefore finding such a rare specimen in west Scottish waters is highly significant. HWDT are awaiting the results of the post-mortem however preliminary results suggest that the whale, a sub-adult male, was in healthy condition; in fact the whale had been eating shortly before being beached as there was still an undigested squid in the stomach. It also appeared that the animal initially stranded alive.

Photographic Identification
Photographic identification enables scientists to track individual animals and monitor changes in their markings over time. Photographs obtained from the public and local tour operators are vital for photo identification analysis as their data complements data obtained from our own research vessel Silurian.

Bottlenose dolphins in Tobermory Harbour
On St. Patricks Day 2011 a group of six Bottlenose dolphins swam into Tobermory Bay. Staff at HWDT used the Tobermory Harbour Association RIB to obtain photographs. Three weeks later three of the same dolphins returned to Tobermory Bay accompanied this time by three different individuals. Data such as these allow us to track the movements of individuals over seasons and can provide a wealth of information about home ranges and movements within these ranges.

In fact six of these dolphins were identified by HWDT in encounters that were reported to us by the public throughout the 2011 season. HWDT also received photographs from an encounter of Bottlenose dolphins off the Island of Barra in the Outer Hebrides. A small and isolated community of Bottlenose dolphins (18) are thought to be resident in the waters surrounding Barra so photos taken in this area by the public are incredibly important to our research allowing HWDT to keep track of any changes to their status.

Killer whales
The West Coast Community of killer whales consists of just nine individuals. Eight of these were sighted by members of the public and tour operators this year and submitted photos to HWDT. Puffin (W09) and Comet (W05) were sighted twice, once in June off the north-west coast of Mull and once in August off the east side of Benbecula. Also sighted in Hebridean waters in May were whales that did not match individuals in either the West Coast Community or Shetland photographic identification catalogues. The photos interestingly showed a yellowish colouring of the eye patch. Dr Andy Foote, who was involved in the identification process, suggests that this colouration indicates the presence of diatoms within the individuals implying that they were at higher latitudes prior to this sighting.

Minke whales
Minke whales also have identifying features that scientists can use to identify individuals. Dorsal fins can differ in terms of shape, colour patches, nicks and notches; many Minke whales have scars on their bodies or colour patches that further allows scientists to identify them from each other. Currently, HWDT do not receive as many identification photos of Minke whale as they do for Bottlenose dolphin, Basking shark and killer whale. We therefore encourage members of the public to take photographs if they get the chance and send the photos to us. If we identify the individual we can tell you who it was, where it was last seen and perhaps even who it was last seen with.

Huge thanks to everyone who reported their sightings in 2011, lets hope 2012 is just as successful. Please help spread the word and ask people to report their sightings to HWDT using our online sightings form. All sightings received will be forwarded to the respective organisations, e.g. all Basking shark sightings are forwarded to the Shark Trust.