Wednesday, January 10, 2007

Dead Porpoises on Scottish Beaches

Are the dead porpoises on Scottish beaches more evidence of global warming?

HARBOUR porpoises are starving to death in the North Sea as a result of rising water temperatures, scientists have revealed.

Climate change has resulted in a dramatic decline in the numbers of sandeels - a major part of the staple diet of the porpoises.

Marine scientists have recorded a significant rise in the percentage of porpoise deaths due to malnutrition. They are also becoming increasingly concerned about the impact of the declining sandeel populations on other species such as the bottle-nosed dolphin and the minke whale, believing this could jeopardise the future of Scotland's booming whale-watching sector.

The potential crisis was highlighted yesterday in a study by a team of scientists from Aberdeen University and the Scottish Agricultural College in Inverness, published in the Royal Society journal Biology Letters.

Previous reports have already revealed that seabird populations around Scotland's coast have been seriously hit by the decline in sandeel numbers.

But, unlike seabirds that only eat sandeels, it had always been assumed that harbour porpoises and other cetaceans would simply switch to eating other fish species when sandeel numbers fell, without suffering any ill-effects. The study, however, suggests that this is not the case.

Sandeels are anchovy-like fish which spend most of their lives buried in the sand before emerging for a few months in the spring when they become a vital food source.

Separate studies have found the number of sandeels living to adulthood falls during warmer winters, when they grow at too fast a rate to be supported by the available food.

The percentage of stranded harbour porpoises on the North Sea coast of Scotland found to have died as result of malnutrition has risen from 5 per cent to 33 per cent in the past six years....

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