Stephen PullingerThe region's coastal waters have been given a reassuring clean bill of health at the start of the school summer holidays.Tourism leaders last night welcomed the biggest study ever undertaken of the state of the UK seas, which reports declining, low levels of pollution and improving marine eco-systems.Stephen Pullinger

The region's coastal waters have been given a reassuring clean bill of health at the start of the school summer holidays.

Tourism leaders last night welcomed the biggest study ever undertaken of the state of the UK seas, which reports declining, low levels of pollution and improving marine eco-systems.

The Charting Progress report, a five-year study compiled by scientists at the government's Centre for Environment, Fisheries and Aquaculture Science (Cefas) also offers hope to the region's fishermen that fish stocks are recovering.

The positive messages come as a welcome boost to the region's tourism economy - worth �471m a year in Great Yarmouth alone - at the start of the main season.

And the report will give extra confidence to beach goers coming in the wake of five destinations - Hunstanton, Sheringham, Cromer, Sea Palling and Lowestoft - winning prestigious Blue Flags this summer.

Cefas chief scientist Mike Waldock said: 'This is a good news story. Most of the trends information shows the input of pollutants declining year on year.'

While contamination by hazardous substances such as mercury had reduced in most regions - remaining largely an issue in the sediment of certain large river estuaries - the outlook was particularly good around East Anglia due to there being no legacy of heavy industrial activity.

Dr Waldock highlighted the clampdown on the use of tributylin (TBT), a toxic antifouling compound banned for use on small boats in the 1980s and large vessels in 2008, as a good example of environmental improvement.

The decline in TBT levels had seen a significant increase in the populations of oysters, mussels and dog whelks (marine snails) around the East Anglia coast.

The concentration of such pollutants was insignificant enough to pose no risk to eating shellfish, he added.

Dr Waldock said contamination of sea water from the overflow of sewage treatment works during heavy storms was also declining as facilities improved; in East Anglia it was almost entirely a winter phenomenon so there was little impact in terms of sea bathing.

One negative of the report was the presence of litter, particularly plastic, found on all beaches surveyed and on the sea bed.

Dr Waldock said: 'While litter is clearly an aesthetic and economic problem - who wants to go on a dirty beach? - the impact is less clear on animal health.'

He said efforts would be stepped up to look at the impact of offshore litter when new EU regulations came into force.

The report, which draws on evidence gathered by scientists around the UK, points to fish stocks improving but not having reached a level of complete recovery judged by the presence of really large specimens.

The scientists also considered the impact of global warming and report sea levels having risen by 14cm during the past century with surface temperatures increasing by 1C since the late 19th century.

Great Yarmouth Borough Council's cabinet member for tourism Graham Plant welcomed the report's findings on pollution as 'excellent news for tourism' and said the sewage overflow problem during storms had been addressed by investment in new treatment works.

Chris Wightman, one of the last fishermen operating out of Lowestoft, said he had seen a marked recovery in fish stocks over the past three or four years with levels of cod, skate and Dover sole all improving.