Don

A shoal of grey triggerfish has become the latest warm-water species to be discovered in the once chilly waters off the British coast.

The fish, whose usual habitat is the tropical Atlantic and the Mediterranean, were discovered two miles off the Isle of Purbeck, Dorset.

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With global warming and higher sea temperatures, marine biologists believe the species could become an increasingly common visitor.

Triggerfish have occasionally been found in the waters around Britain and Ireland, but not in a large group. Biologists believe they could be breeding because offspring were among the shoal found off the Dorset coast.

Dr Ken Collins, of the Southampton Oceanography Centre, found the triggerfish (Balistes capriscus), while he was photographing an artificial reef.

He said: "Ten years ago it would be extremely rare for them to come this far north.

"But in recent years they have been known to stray up into our waters during the summer and leave when it gets too cold for them.

"I have only seen two of them at a time and what is exciting about this discovery is the large number of them.

"There were about a dozen, including one or two smaller members. This may be the first sign of them breeding here and this would indicate that they are staying for longer periods."

Triggerfish, which can grow to 25in long and weigh up to 15lb, get their name from their dorsal spine which can be triggered to lock upright, providing a defence against being swallowed.

They are among a number of tropical fish discovered off Dorset in recent years.

In 2000, fishermen caught a zebra sea bream, normally found off the West African coast, off Portland.

In the summer of 2001 trawlermen at Lulworth Cove caught a batch of rare scaly cheeked wrasse. The bright red fish usually live off the Spanish and African coasts.

In June 2002 a group of bright purple jellyfish, called by-the-wind sailor fish, were found washed up at Kimmeridge Bay. Their normal habitat is the deep waters of the Mediterranean.

Earlier this year holidaymakers were warned of the dangers of the "kick-boxing" mantis shrimps found in Weymouth Bay. Their normal home is near the Equator.

Two weeks ago, divers photographed a pregnant short snouted seahorse searching for a place to give birth off Purbeck.

Other discoveries include a loggerhead turtle and a weaver fish.

Chris Brown, a marine biologist at the Weymouth Sea Life Park, said: "The Mediterranean has always been a few degrees warmer than the English Channel.

"But in recent years we have seen a trend of more and more fish heading north and of course they turn up off the south coast, particularly Dorset because it is central.

"All this points to global warming. Our seas are getting warmer and that is attracting the fish." The warmer water could see a record number of weaver fish this year, scientists warned yesterday.

The 4in fish buries itself in sand close to shore and releases venom from its dorsal spines if trodden on. It has represented a beach hazard on and off for years but this summer scores of bathers around the coast have already fallen victim to it.

Researchers from the Government-funded Centre for Environment Fisheries and Aquaculture Science (CEFAS) said yesterday that they had recorded higher than usual numbers in the North Sea.

Dr Jim Ellis, a marine biologist at the CEFAS laboratories in Pakefield near Lowestoft, Suffolk, said a recent survey had found an "awful amount" of weaver fish in the southern North Sea.

"If the sea conditions are just right for a species, they will have a high survival rate when they breed a lot," he said.

"Nobody really knows what leads to higher numbers of weaver fish reaching adulthood. It could be that warm currents provide favourable breeding conditions."

But Dr Ellis said the risks should be kept in proportion. "There will be far more people stung by wasps this summer than weaver fish," he added.

http://www.telegraph.co.uk/news/main...12/ixhome.html

walaj

Last week I was looking at photos of several trigger fish taken by friends diving off the dorset coast. They can be very terittorial and tried to bit one of them.

Shame I am not diving this season