Dolphins flourish in North Sea
Survey finds huge influx of warm water marine life
Saturday April 2, 2005
Warmer water is washing unprecedented numbers of "southern" fish and other marine life into the previously inhospitable North Sea, according to a survey by university biologists.
More than 600 sightings of dolphins and whales - some in schools of more than 200 - have been recorded in a year-long audit of waters between Britain, Scandinavia and Germany.
Large shoals of sea bass, usually found off Cornwall, have added to the new ecology, astonishing fishermen, who described the number of squid in particular as "unreal". A volunteer fleet of fishing craft and pleasure yachts working for Newcastle University also charted an invasion of red mullet, pilchard and velvet crabs, all indicators of warmer seas.
Notable sightings include a white-beaked dolphin and calf, and Risso's dolphins, which are thought to have followed migrating squid from the English Channel. The increase in prey has meanwhile tempted colder water species such as the killer whale to increase in numbers, harrying growing populations of seal.
"The sea is changing," said a trawler skipper, Stephen Moss, whose ship, Green Pastures, of Blyth, Northumberland, has increasingly been trailed by dolphins in the last year. "We've been catching commercial quantities of red mullet and occasionally pilchard, and this year we were hauling in mackerel right up to Christmas. We're definitely seeing changes in the water temperature. The number of squid now is just unreal."
The survey was organised by the university's Dove Marine Laboratory at Cullercoats, just north of the mouth of the Tyne, where tallies are being compared with records from previous years.
Joanna Stockhill, the coordinator of the project, said: "Other recent surveys have suggested an increase in warmer water species in the North Sea, and everything we have got is pointing in that direction.
"Risso's dolphins, which are primarily a warm water species with few previous records from the North Sea, account for 12% of our 614 whale and dolphin sightings. The number of common dolphin also support the warming theory. They've usually been found off the south-west coast of Britain and only rarely in the North Sea, until recent years."
Sightings have been monitored and backed up in most cases by details of behaviour, to avoid identification mistakes. Volunteers were also encouraged to get photographic proof, such as Linda Lane Thornton's picture of the pair of white-beaked dolphins.
"We've been sailing from Blyth for three years and we're definitely seeing an increase in whales and dolphins," said Mrs Lane Thornton, the secretary of the Royal Northumberland Yacht Club. She and her husband, Andy, have been trailed regularly in their yacht by dolphins this year.
"Their reports are among quite a few which describe these species following vessels, rubbing on the hull and trying to score the occasional fish escaping from trawlers' nets," said Dr Stockhill. One of the biggest of the 614 sightings was a shoal of 250 white-beaks 26 miles off Cullercoats.
The survey, backed by the Sea Watch Foundation, which monitors whale and dolphin numbers off Britain's coasts, follows previous recent records of exotica such as a semi-tropical rainbow wrasse caught off Southend pier, and landings of sea cucumbers and anchovies in the North Sea. The team is drawing up a "sustainable future" plan for stock management in the North Sea.
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