More than 500 dolphins, porpoises and whales became stranded on British beaches in 2010. Photograph: Greenpeace / PA

By John Vidal, environment editor, www.guardian.co.uk 
Monday 22 November 2010 15.15 GMT Marine scientists will this week appeal for volunteers to watch for stranded whales and dolphins and report instances as soon as possible to understand why so many are being found on beaches. It follows the unexplained mass stranding of 33 pilot whales found dead on Rutland island off the coast of northwest Ireland last month and more than 500 dolphins, porpoises and whales stranded on British beaches this year. New figures to be released this week will show that whale and dolphin strandings are increasing. According to the UK Cetacean Strandings Investigation Programme (CSIP) there have been 9,494 recorded strandings on British coasts in the past 20 years, but the number could be much higher because many are likely to go unreported. Most are washed ashore dead but around 10% are still alive. Strandings have increased by nearly 25% since central records were first kept by CSIP. “In the first 10 years there were between 300 and 400 a year, but since 2000 there have been more. The highest number was in 2003 when 800 were found stranded. Now there are around 500 a year,” said Robert Deaville, project manager for CSIP. “We under-report the numbers. There are several very good volunteer networks in the south west, Wales and Scotland, but we do need more people in England,” said Deaville. … Post mortems show that most stranded animals have died from natural causes but high-powered sonar used by navies and the oil and gas industry is increasingly associated with deaths. … Scientists think the large pod of pilot whales found dead on Rutland island, Donegal last month was the same seen off the outer Hebrides a few days earlier. It was reported that the Royal Navy had been exercising in the region and could have disoriented the pod with its sonar. Pilot whales are known to be sensitive to acoustic disorientation and have been found to suffer from a condition known as “gas embolism”, which is common to the bends suffered by human divers. … • For more information about how to report a stranding visit the CSIP website.

Keep an eye out for stranded dolphins, urge scientists