An extraordinary winter sighting of five sperm whales off the coast of North West Scotland this week could be a reflection of climate change and warming sea temperatures, says a leading marine scientist.
The sperm whales – one of the true giants of the oceans – were first seen by creel fishermen between Loch Torridon and South Rona on Monday. They initially thought they were humpback whales and alerted boat operator Nick Davies from Hebridean Whale Cruises based at Gairloch who is involved in a project collecting cetacean (whale, dolphin and porpoise) data for Sea Watch.
He went out to the location, and when he arrived was astonished to recognise sperm whales diving together for food – the first time he has ever seen them.
Dr Peter Evans, director of marine conservation research charity Sea Watch, was able to confirm the sighting from his photographs and says:
” In past decades, most records of sperm whales in British waters have been of lone adult males around Scotland mainly off the Northern Isles and the Hebrides. Increasingly, however, adolescent males have occurred in our waters, sometimes in groups of 5-10 individuals.
“Sightings of groups of sperm whales have tended to occur mainly in summer so this winter sighting of a group is notable not just for the time of year but for its inshore location. The species normally lives in waters of 1,000 metres or more depth, beyond the continental shelf edge. Here they have sought out the deepest area of NW Scotland – the Inner Sound.”
“The increased occurrence of winter sightings in Scottish waters could be a reflection of climate change, with their main prey, squid, becoming more abundant locally in recent years, resulting in animals staying through the winter to feed rather than travelling into lower warmer latitudes.”
Sperm whales are amongst the largest mammal species in the world. Adult males can weigh in at up to 45 tonnes – the iconic London Routemaster double decker bus weighs less than 8 tons, unladen!
Nick Davies explains:
“I was excited at the prospect of humpback whales, but never expected to see sperm whales.
“When I was about 8-9 miles away I could see their spouts – it looked like a flotilla of yachts and as I got nearer it was obvious from their flukes (tails), that they were sperm whales. There was one enormous animal and four smaller ones, and they were synchronised diving, going down for 30 minutes or so at a time.
“Fishermen have been telling me that for the past four or five years they have been seeing increasing amounts of squid in their nets, and it seems that this was perfect for the sperm whale.”
The sightings, made on Monday February 18th were in waters one mile east of Caol Rona in the Inner Sound between the islands of Rona and Raasay – close to an area where the in-shore waters are at their deepest at 1,000 ft.
Sea Watch is now analysing Nick’s photographs to see if they can be match the tail fluke markings in the trailing edge to any individuals included in a North Atlantic catalogue of individuals photographed from locations as far apart as the Azores and Madeira to Iceland and Norway. Matching of individuals between locations gives us a better idea of the movements of this wide-ranging species. Individuals have already been matched between the Azores and Norway (Andenes and Tromsø). And in 1997, a photo image from Andenes matched a male stranded on the west coast of Ireland.
According to Sea Watch’s national database, there have been just 94 separate sightings in British waters since 1974, with the largest group on record being of 20 animals seen off Mousa in the Shetland Islands in 2007.