The Nina May is used as a 'dummy' responsible for the catch from 12 trawlers and in fact rarely leaves her moorings.

By assigning the catch from the other trawlers to the dinghy, the trawlers can avoid the risk of having their licences suspended if they are caught breaking the rules, the vessel's owner, Robin Carter, told a Greenpeace researcher.

"Why it's on the Nina May is that if you get an offence, a log book offence, or some silly little offence, the ministry would freeze your licence," he was quoted as saying. "You wouldn't be allowed to sell your licence or sell your quota on it.

"We took the precaution - because we got caught once - of taking the fish [quota] off all the boats and just putting it one the one boat. It's on there for no other reason than that licence will never get frozen because it just goes in and out of the river and hopefully never commits an offence."

Will McCallum, head of Greenpeace's oceans campaign, said: "For many small businesses struggling to keep afloat, the Nina May is a living symbol of the government’s failure to properly manage and regulate the fishing industry.

"And it doesn't seem right that a big fishing company can hoard up all its quota on a dummy vessels so its other trawlers can carry on fishing even if they are caught breaking the rules. The government should look into whether this is a widespread practice."