SWARMS of jellyfish in the sea off the South East Cornwall coast have been causing a problem to local fishermen who have been pulling in their nets to find hundreds of them trapped inside.

Some of the fishermen have also been stung as they have had to handle so many to free up their nets, but the jellyfish are generally regarded as harmless.

They have been identified as barrel jellyfish, a large species which can grow up to one metre across and weigh 30 kilos. Because of their shape and size, they are sometimes referred to as 'dustbin' jellyfish.

During the last week, a few of the jellyfish have been washed ashore and found on Looe, Millendreath and Plaidy beaches. Another, measuring approximately 600mm across was found at the edge of the West Looe River.

Looe harbourmaster Jeff Penhaligon said: 'They have been around for about eight weeks but the numbers are now dying down a bit.

'They are a nuisance to the fishermen, some of them have quite bad hands through stings from handling so many.

'Their nets have swamped.'

Caz Waddell, marine conservation officer for the Cornwall Wildlife Trust, said there is no need for the public to be alarmed but she would advise people not to touch the jellyfish.

'Some people are more sensitive to these jellyfish and could find them irritating to the skin, but others may not,' she said.

'It's not a huge surprise that they are being caught in fishermen's nets as they normally spend most of their time in deep water.'

James Wright, assistant curator at Plymouth's National Marine Aquarium, said: 'Last year saw an unprecedented number of barrel jellyfish in our waters. This year the indications are they are returning.

'This influx though is starting earlier.

'While they are not unusual in UK waters, the numbers recently have been surprising.

'They are harmless and actively pump seawater through their bodies to trap plankton.'

Last year's influx of barrel jellyfish was the largest so close to shore since 2002.