The Hebridean Whale and Dolphin Trust (HWDT), established in 1994, is carrying out research into the health of whales, dolphins and porpoises using photogrammetry – the science of taking measurements from photographs.
Silurian, the trust’s specialised research yacht (click here to track the vessel at sea), has been collecting data on cetaceans (the collective name for whales, dolphins and porpoises) since 2002. It was even used during the filming of the BBC’s Blue Planet series. Its photo-identification research has so far catalogued 230 minke whales, some of which have been returning to the same area for more than ten years.
Over the last 15 years, Silurian has travelled more than 100,000 kilometres while surveying Hebridean waters from Islay to Cape Wrath and west of the Western Isles. Data collected onboard forms the largest continuous database of its kind in the UK, comprising over 6,000 hours of underwater sound recordings, and over 30,000 animal records. The current series of expeditions into the waters of Scotland take place until October this year.
The new technology works by pointing two lasers attached to the main identification camera 10cm apart onto the side of an animal at the same time a photograph is taken. ‘From those two dots on the image we can work out all sorts of things,’ says Lauren Hartny-Mills, science officer at the HWDT, ‘the health of the animals, how well they’re doing, how big they are, and whether they’re fully grown adults or younger animals. It will also help us look more closely at marks and scars and determine how those have been caused, whether by interaction with debris in the environment or natural markings from other animals.’
Fiona Manson, a marine specialist at Scottish Natural Heritage, said: ‘The Hebridean Whale and Dolphin Trust is making an important contribution to marine conservation in Scotland. We’re excited by the innovative techniques being used to find out more about the health of wildlife in Scotland’s seas.’
Because cetaceans are such long-lived animals that reproduce slowly, scientists at the Trust say it’s important to monitor population dynamics and composition, as any changes in health or behaviour may take a long time to show. Other issues facing cetaceans, as well as interactions with man-made objects such as marine plastic and fishing gear, are underwater noise (which interferes with their echolocation) and the accumulation of pollutants in their systems.
For example, in 2016, a member of the West Coast of Scotland killer whale pod was found to have one of the highest levels of polychlorinated biphenyl (PCB) pollution ever recorded in the species after she was washed-up on the Isle of Tiree in the Hebrides.
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