ONE of the world’s largest fish farming companies has accidentally killed more than 175,000 of its caged salmon in Scotland while trying to treat them for lice and disease, according to internal Government memos.

Blunders by Norwegian multinational, Marine Harvest, have cost millions of pounds and led to over 600 tonnes of salmon having to be incinerated.

Campaigners have accused Marine Harvest of treating salmon cruelly, and warn that lice and diseases are “choking the Scottish salmon farming industry to death”.

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The worst incident took place in July and August on a salmon farm in Loch Greshornish on the Isle of Skye. Some 95,400 fish were killed by a new device called a thermolicer, which is designed to rid salmon of the sea lice. Officials estimated that the losses cost Marine Harvest over £2.7 million.

Another 20,000 salmon were killed at Loch Greshornish fish farm by other attempts to rid them of sea lice using chemicals.

Earlier 60,000 salmon had been killed by hydrogen peroxide used to treat them for amoebic gill disease, this time at a Marine Harvest fish farm in Soay Sound off the Isle of Harris.

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Marine Harvest pointed out that the salmon killed in the “unfortunate” thermolicer incident had been weakened by gill disease. “We regret any loss of fish and are always mindful of the welfare of the fish and aim to continuously improve our methods to address changing environmental circumstances,” said the company’s manager Steve Bracken.