© Wessex News Agency/Clare RileyConcern: A dolphin found at Smeaton's Pier in St Ives, Cornwall is the tenth discovered dead along West Coast beaches in as many days, prompting fears over what could be killing them.
Pollution, trawler nets, inclement weather and jet skiers have all been cited as likely causes for the demise of these marine animals.
Clare Riley was among those who found the latest dead dolphin on the beach near Smeaton's Pier in St Ives, Cornwall.
'It was sad to see - I've been in Cornwall for six years waiting and hoping to see dolphins and I was finally rewarded two weeks ago with an awesome display of a pod playing and surfing the waves at Gwithian,' she said.
Another resident, Tony Mason, said: 'I saw them at Gwithian last Sunday, swimming around jet skiers. To then find that one dead was so sad. Such a beautiful creature.'
Between January and March last year, 61 dolphins, porpoises and whales were found dead around Cornwall's coast, the steepest rise in the death toll since 2006, according to the Cornwall Wildlife Trust.
They said previous post-mortem tests showed creatures washed up on the shores had died from a number of causes, including pollution, illnesses, natural causes and after being caught in fishing nets.
Scientists have been working with the fishing community to fit sea-going trawlers and other boats in Cornwall larger than 14m with 'pingers', which emit underwater noises to drive dolphins away from fishing nets.
Abby Crosby, from the wildlife trust, urged people to report any dead whales, porpoises or dolphins.
'The most important piece of advice is for people to report these sightings of stranded cetaceans so we can gather more information on what is killing them,' she said.
Paul Trebilcock, from the Cornish Fish Producers' Organisation said: 'Cornish fishermen have been at the forefront of using acoustic pingers.
'All of this is hopefully contributing towards a reduction in the interaction between fishing gear and cetaceans.'
A wildlife trust spokesman added: 'Volunteers have been collecting data on strandings for many years and we now have over 5,500 records on our database, the earliest dating back to 1308.
'This information is vital in helping us to conserve wildlife and cannot be learnt from studying live animals. We can learn about causes of death and threats to survival.'
Comment: Last month in two separate incidents, thousands of dead fish were discovered on Pentewan and Marazion beaches in Cornwall.