GLOBAL warming and overfishing have been blamed for a dramatic drop in the number of whales in Scottish waters.

In some areas, sightings of the minke whale, the most populous of the mammals, are down by 50% It is believed a reduction in the number of sand eels, the whales’ main diet, has driven them to the deeper waters of the Atlantic.

Sand eels have been used to produce feed in the burgeoning number of salmon farms around the Scottish coast and have become scarcer as a result.

Basking sharks, which feed on tiny plankton, continue to be seen in large numbers. However, there have been just 200 sightings of minke whales this year compared with 406 in 2003, according to the Hebridean Whale and Dolphin Trust.

“August and September are the two months when we expect to see the most whales but this year we have had less than 20 recorded sightings,” said Laura Mandleberg, sightings officer for the trust.

Sea Life Surveys, a company that runs whale-watching tours from the isle of Mull, promise a 98% chance of spotting a whale but this summer managed only two sightings a week. Another Mull operator, Inter Island Cruises, recorded only six sightings in the whole of August.

The whale-watching industry attracts thousands of tourists and is worth £10m a year to the local economy.

“People are not going to come if they can’t see whales,” said a spokesman for the trust, an independent research body. “There has been a dramatic and sudden disappearance this year and it is concerning. We hope it is a blip.”

The lack of sand eels is also leading to a reduction in local seabird populations.

The Royal Society for the Protection of Birds, the National Trust for Scotland and the Scottish Wildlife Trust have reported failures of species — including guillemots, razorbills, Arctic terns and kittiwakes — in west coast reserves of Tiree, St Kilda and Canna.

“It is of great concern that some birds are having to find an alternative diet just to survive,” said Stuart Housden, director of RSPB Scotland.

“We need to monitor closely their feeding habits to see what effect this has on their breeding success in the future. This is the first time the west has been affected and we can only speculate as to why but climate change must be considered. Seabirds are excellent barometers of the state of the marine environment and we must do all we can to conserve these iconic species.”

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