Speaker: Tom Brereton
Tom Brererton, as Research Director of Marine Life for over 30 years and 25 years leading Naturetrek trips, has as an in-depth knowledge of the lives and habits of the Cetaceans.
In the area covered in Tom’s talk 30 species of Cetaceans have been sighted with 15 recorded on a regular basis. We were shown how where species were found depended on the depth and temperature of the sea and the availability of the food they required.
This was highlighted in the first area Tom covered.
The Hebridean islands are on the continental shelf, enabling Cetaceans like the Minke Whale, Harbour Porpoise, and Common Dolphin to inhabit these waters, feasting on shoals of fish such as Mackerel. Moving west away from the isolated archipelago of St Kilda towards Rockall, over the Rockall Trough, the depth of the ocean plummets to over 1,000 metres. Here are found 12 species, notably Pilot, Sperm and Bottlenose Whales, who mainly live off squid.
The magnificent Sperm Whale provides one of nature’s most spectacular sights, lifting its triangular flukes (tail lobes) high out of the water as it begins a feeding dive.
Tom’s clockwise journey took him next to the seas surrounding the islands of Orkney and Shetland. Here the sea is relatively shallow and home to a number of Porpoises and Dolphins, notably the Risso’s Dolphin, who often possesses rack marks and becomes white when older. Their preferred diet is a combination of Cuttlefish and Squid.
Tom also mentioned the star of many a television programme, the Killer Whale or Orca. They have been captured on film hunting in their pods. Up to 600 are now found in the Norwegian Sea.
On the east coast travelling southwards the only significant area of deep water is off the Moray Firth. This is a good area for mainly grey Bottle-nosed Dolphin who plunder whatever food source they can. They number around 200 though since 2016 a sizeable number, estimated at 80, have been seen off the Northumberland coast. Tom described them as bullies.
Cetaceans in South-West England have been impacted by changing sea temperatures. White-beaked Dolphin, first seen in 2007 in Lyme Bay, have seemingly disappeared due to a combination of depleted white fish numbers and an increasingly warm sea. But the arrival of large numbers of octopus has led to Risso’s Dolphins following them.
Shoals of Krill are now found in the deep waters off Cornwall and West Wales, known as the Celtic Deep. They have attracted the world’s second largest mammal, the Fin Whale.
One of the joys of going out on a boat trip is being accompanied by Common Dolphins. They seem to be as nosey as their avian cousin, the Robin.
Tom started and finished with the Humpback Whale. His last photograph showed one with Golden Cap in the background. Seeing them breaching is another spectacular wildlife sight and an excellent way to end his much appreciated talk.
Andrew Harrison
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