North Sea cod and sole stricken by sunburn

Fish in the seas around Britain are suffering sunburn and blisters caused by the thinning ozone layer, symptoms of a drastic change in environment that threatens to wipe out species once common to our shores.

Fish in the seas around Britain are suffering sunburn and blisters caused by the thinning ozone layer, symptoms of a drastic change in environment that threatens to wipe out species once common to our shores.

The ozone layer shields the earth from harmful rays that can cause skin cancers and cataracts. Studies show that the ultraviolet rays, normally filtered out in the upper atmosphere, are harming Dover sole, cod and shellfish, including mussels and oysters.

The problem, scientists believe, affects young fish and fish spawn, which breathe through their skin because their gills have not yet developed and they have no scales which could help deflect the rays. Freshwater fish are also thought to have been affected, along with newts and frogs.

The proliferation of ozone-eating chemicals called chlorofluorocarbons (CFCs) has led to the thinning of the ozone layer above Britain by 10 per cent in Spring when fish spawn and when they are most vulnerable to the most damaging rays, known as UVBs.

These rays blister the skin of young fish and cause it to thicken, slowing their oxygen intake, stunting their growth and leaving them more vulnerable to predators. The UVB rays also react with pollutants in the water to produce toxins up to 10,000 times more potent than normal.

The effects were discovered by researchers at the Plymouth Marine Laboratory, which works for government agencies such as the Ministry of Agriculture, Fisheries and Food and the Department for the Environment, Transport and the Regions.

Scientists subjected samples to laboratory tests and found white fish and shellfish suffered blisters, impaired development and other abnormalities. Fish such as turbot, which is heavily pigmented, suffered no ill-effects.

"They are suffering what we would call classic sunburn," said Iain McFadzen, research eco-toxicologist at the laboratory. "Their skin thickens and peels, as it would do in humans. These fish have no protection against the rays because they have never needed to evolve one until man began to influence the atmosphere.

"The fish grow extra layers of cells as a defence mechanism, but this means the oxygen they need takes longer to get into the system. They don't mature and they have to remain in areas of plankton for their food. That means they are likely to be eaten by larger predators. It will be another nail in the coffin for fish stocks."

There is little that can be done in the short term to improve matters. "I think we're stuck with it," said Mr McFadzen. "We can hardly offer them sunscreen and we can only hope the environmental commitments are going to be fulfilled by the major powers and developing nations."

The thinning of the ozone layer, often incorrectly referred to as a "hole", was first identified in 1985 and is caused by CFCs that include chlorine compounds found in aerosol sprays, refrigerants, solvents, and firefighting halogens.

Last month, scientists warned about the risk of ultra- violet radiation that extends from Antarctica over the tip of South America into populated areas. In Punta Arenas, the most southerly city in Chile, 120,000 residents stay indoors as much as possible.

Second-stage health alerts, cautioning that unprotected skin would burn after just seven minutes' exposure, were also issued in Ushuaia, Argentina, on the nearby island of Tierra del Fuego. People going out between 11am and 3pm were urged to wear dark glasses, sunblock, long sleeves and a wide-brimmed hat.

In September, Nasa scientists said the seasonal ozone opening over Antarctica was the deepest on record, covering an area 50 times the size of Britain, approximately 11 million square miles.