Britannia ruins the waves: how pollution and over-fishing are destroying sea life

Fish are changing sex. Species are disappearing as breeding patterns collapse. The food chain is in chaos as temperatures rise, says the first ever major audit of the state of our seas. Severin Carrell reveals what ministers will say on Tuesday about the damage being done to British waters by industry and global warming

Britain's seas are seriously ailing and the species that depend on them suffering as never before. The most comprehensive "health check" ever made of the waters around our shores has revealed that, while Britannia once ruled the waves, now it is helping destroy what lives beneath them.

Britain's seas are seriously ailing and the species that depend on them suffering as never before. The most comprehensive "health check" ever made of the waters around our shores has revealed that, while Britannia once ruled the waves, now it is helping destroy what lives beneath them.

Fish stocks are on the brink of collapse. Species are changing sex because of pollution. Dolphins and porpoises are being killed at unprecedented rates. Water temperatures are rising, and the seabed is being destroyed.

In a disturbing insight into the state of our seas, the government-led investigation has found clear proof that the seas around the British Isles are already suffering the effects of global warming - threatening the survival of fish such as cod and raising the risk of a sudden, catastrophic change in weather patterns.

The study, compiled by the Department for Food, Environment and the Regions (Defra) after 18 months of reviewing all current marine research, found that water temperatures and sea levels are now rising around Britain, while salt levels are dropping because of melting Arctic ice caps. Meanwhile native plankton species - vital to the survival of many fish stocks - are slowly disappearing.

This deeply worrying picture has emerged from 900-page report, which is being published by ministers on Tuesday, into the true state of the seas around the British Isles - historically one of the world's richest marine environments. The audit, which has been peer reviewed, reveals how:

• sea temperatures have risen by 0.6C a decade, and by up to 1.5C in winter;
• sea levels are rising by up to 2mm a year because of melting ice caps and increased rainfall;
• sea water is becoming more acidic because of increasing carbon dioxide levels in the air;
• fish, such as cod, haddock, herring, blue whiting and sole, are being fished outside safe limits, with cod "in danger of collapse";
• common skate and angel shark have disappeared from the Irish Sea and the Channel;
• cold-water plankton - the most basic food stuff for young cod and other native species - is moving northwards and being replaced by warm-water plankton;
• deep-sea trawlers are harming fish such as orange roughie and anglerfish, and devastating ancient and fragile coral beds off western Scotland;
• winter storms are growing more intense and wave heights increasing by 30cm a decade, risking flooding and cliff erosion in regions such as East Anglia, north Wales and southern England;
• estuaries such as the Mersey, Clyde and Tees are showing "undesirably high" toxic contamination from heavy metals and chemicals, which has led to flounder and dab showing signs of cancer and suffering sex changes;
• a "significant" number of shellfish farms are unsafe and beaches are being closed due to sewage contamination;
• massive new offshore windfarms off Wales, north-west England and the South-east pose a "major challenge" to marine life.

The document forms a crucial part of a new Government campaign to combat climate change and introduce tough new controls on over-fishing, campaigns that will be stepped up this week.

Elliott Morley, the environment minister who oversaw the report, told The Independent on Sunday: "For the dwindling band of doubters, I would really recommend that they look at this report. It demonstrates there are serious problems with climatic change, and we've really got to get a grip on it. The longer we delay taking effective action, the more difficult it will be to turn things around. Even a five-year delay could be significant."

He warned that these trends could lead to the weakening of a crucial ocean current and weather system that keeps Britain warm, which is known as the North Atlantic Oscillation and is connected to the Gulf Stream. "This is new. These are the kinds of things which have just appeared on the radar screen." There was, he claimed, an "urgent" need to start preparing an even more sweeping global agreement to cut climate change gases to replace the Kyoto Protocol despite US opposition.

The fishing industry would also get a rude shock, he claimed. "This report makes very clear the impact of commercial fishing on the marine ecosystem. We can't go on with these unsustainable levels of fishing. In that respect, it's very powerful."

The report, based on 800 pages of scientific analysis, also uses a "traffic light" system to show how the health of the seas in 22 key areas. A healthy "green light" is awarded for only three of them - oil pollution, oil spills and the health of sea mammals such as seals.

The most heavily used colour is amber, for 12 areas such as human sewage, radioactivity, salmon farming and chemical pollution, which it claims have "room for improvement". Even so, sea birds are still at risk of death from trawler nets, oil spills and pollution, and salmon farms are still threatening wild salmon with interbreeding and sea lice.

The study says that chemical and radioactive releases are getting better, but it warns that some persistent chemicals, such as hormone-disrupting chemicals causing sex changes, are not properly understood or monitored. Farming fertilisers are still causing serious problems for some ports and regions, leading to algeal blooms and unchecked seaweed growth.

However, red "warnings" are slapped on seven areas: the collapse of key fish stocks; the unprecedented changes in plankton species; the deaths of dolphins and porpoises from trawler nets; a collapse in some North Sea bird populations due to overfishing of sandeels; the 50 non-native species which have arrived in British waters; the sea life affected by climate change; and the beaches still despoiled by litter.