Sunday, July 15, 2007

Common dolphins not are rare specie in the North Sea...anymore!

THE common dolphin - paradoxically once one of the rarest marine mammals seen in the North Sea - has been spotted this year in unprecedented numbers, it was revealed yesterday.
Common dolphins - a familiar sight in the warm waters of the Mediterranean - have been irregular visitors to the colder waters off Scotland's east coast for at least 30 years.

But this year massive pods of the cetaceans - up to 300 strong - have been monitored by scientists in the Moray Firth which is already home to large resident populations of bottlenose dolphins and harbour porpoises.

And the influx of the common dolphin is believed to be a direct result of rising temperatures which have already driven cod stocks further north from their traditional spawning grounds.

Average temperatures in the North Sea have risen by 1C over the past 25 years. And earlier this year a team of researchers revealed that harbour porpoises were starving to death in the Scottish waters due to rising water temperatures which had resulted in a dramatic decline in sandeels - a major part of their staple diet.

The first inkling of an unprecedented arrival of common dolphins into Scottish waters came last month, just days before the start of National Whale and Dolphin Watch week, when marine biologists reported "unusual sightings" of them off northern Britain.

A group of between 60-100 common dolphins were seen by a ferry crew north of Fair Isle. Last week, during the watch week itself, over 200 common dolphins were seen off Freswick in Caithness.

And yesterday the Gardenstown-based Cetacean Research and Rescue Unit revealed a pod of 300 common dolphins had been spotted in the southern trench of the Moray Firth, it's deepest stretch.

Kevin Robinson, the director the cetacean unit, said: "The arrival of common dolphins to the Moray Firth confirms that sea temperatures are rising.

"In 2003, we found a stranded common dolphin along the Aberdeenshire coastline, but this is the first time we have encountered these animals at sea."

Dr Peter Evans, the research director of the Sea Watch Foundation, explained: "This is probably related to the continued strong flow of the North Atlantic current which is likely to have brought warmer water species of fish like anchovy and pilchard - typical prey of common dolphins - into more northern waters.

"But there is no evidence the common dolphin is going to make the Moray Firth its home.
"It is not going to drive away bottlenose or harbour porpoises as they feed on different prey."

Quick "Facts about Dolphins"