The two activities are Shetland's main non-oil industry, employing more than 800 people. Salmon farming is likely to be the worse affected. The Scottish Office, imposing the ban, said it was necessary to protect people from eating possibly oil-contaminated fish and shellfish. It said the action had the full support of the local industry.
It is hoped the ban will also restore failing consumer confidence. Yesterday Marks & Spencer and Tesco suspended buying of Shetland salmon. Other big supermarkets may follow.
Meanwhile, salvage experts said the tanker was breaking up after three days of gales and huge waves. The stern, containing the bridge, crew accommodation and engine room, was tearing away from the main section holding the crude oil.
Gert Koffeman, head of Smit Tak's salvage team in Shetland, said that would help to keep the crude oil tanks stable, resting in one unit on the sea bed. Mr Koffeman believes more than 50 per cent of the oil is still on board. If the weather improves, he hopes that the oil can be pumped next week into a barge to be brought alongside the Braer, and then to a tanker out to sea. Some might be pumped out and taken away by road.
Smit Tak has abandoned any idea of salvaging the tanker and is concentrating on its cargo, which is continuing to pour into the sea and spread north, polluting inlets, killing marine life and hundreds of birds and threatening 16 fish farms. Yesterday more gales prevented any real progress in containing the huge slicks, which are being broken up and mixed deep into the sea by waves and winds.
The Smit Tak salvage ship Orca arrived in Lerwick, Shetland's capital, last night to join the powerful tug Smit Lloyd 121. Now the salvors need only the giant barge that can take up to 8,000 tonnes of oil, due from Rotterdam on Monday.
The no-fishing zone stretches in a huge horseshoe round Sheland's southern end. Its southern tip begins three nautical miles south of Sumburgh Head, and it stretches about 22 miles up the east and west coasts, going about seven miles out to sea. It covers a quarter of the island's fish farms.
Martin Anderson, a fish farmer, said: 'If we're unable to sell the fish and unable to claim compensation we could be bankrupt within four weeks.' He and two partners had been about to sell pounds 50,000 of fish.
The fish farming industry was already in difficulty because of overproduction, the recession and dumping of cheap Norwegian salmon. The Shetland Fishermen's Association welcomed the exclusion zone as essential to preserve its good name.
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