This is the shocking image showing how one of Northern Ireland's most unspoiled beaches was invaded by killer jellyfish.

Mauve stingers (Pelagia noctiluca) lie scattered across the white sands of Whitepark Bay after washing ashore earlier this week.

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Ireland’s only salmon farm put extra measures in place to protect stocks against the jellyfish, as it has only just gathered its first harvest after more than £1m worth of salmon were wiped out by mauve stingers in 2007.

However, wildlife experts say it is now safe to go back in the water, with only small numbers of the stinging jellyfish found yesterday during surveys of beaches on the north Antrim and north coasts.

Marine biologist Gary Burrows of the Northern Ireland Environment Agency said nothing like the large bloom seen at Whitepark Bay has been detected since.

“Some coastal councils have done beach surveys and there are very few jellyfish,” he said. None were found at Portballintrae or Whiterocks, while only small numbers were found at Coleraine or Portrush, he said. However, he warned that mauve stingers are always present in our waters and advised swimmers and other sea-users to stay alert.

“There are no indications of any more large blooms, but anything can change with the next tide,” he said.

“They’re always present around the Irish coast. There are always jellyfish in the water — of the eight species we have, four can deliver a powerful sting.

“The Pelagia noctiluca are small in size, have a globe-shaped bell, a warty appearance and are an overall purplish colour.

“It can glow brightly at night if disturbed, as the second part of its Latin name suggests. Its sting is powerful and can produce a very severe reaction.”

Mass strandings of jellyfish are linked to persistent winds, but there is a growing consensus that climate change and overfishing of natural predators are boosting the numbers of jellyfish blooms throughout the North Atlantic, Mr Burrows said.

“They appear to be increasing for the simple reason that jellyfish reproduce in bigger numbers in warmer seas. Some of their predators are found in much smaller numbers as well,” he said.

Hundreds of thousands of salmon reared at what is now Glenarm Organic Salmon were wiped out in November 2007 when billions of mauve stingers descended on their nets at Glenarm Bay and Red Bay.

The sheer mass of jellyfish, covering an area of up to 10 square miles and a depth of 35 feet, turned the sea red and suffocated the organically reared salmon.