The biggest threat to Britain's carp is Eastern European migrants

The fish are considered a delicacy in many countries such as Poland, Romania and Bulgaria.

While anglers here traditionally throw them back, the immigrants are more likely to take the freshwater fish home to serve up for dinner.

Commercial fishery owners say thefts of fish have surged in the past few years with the influx of eastern Europeans.

With lake owners spending around £1,000 on a single 25lb carp to attract anglers the poaching is causing the industry enormous expense.

According to the Professional Coarse Fisheries Association, there have been reports of some thieves even using dustbins to take away their catches.

Others have been seen on the banks gutting fish before taking them home to eat. Of 60 fish-eries surveyed by the PCFA in England and Wales, 34 said they were regular victims of thefts and the problem had worsened in the last two years.

Of those, 25 thought immigrants were responsible for removing the fish for the table.

Twenty-one also thought professional thieves selling them on to other fisheries were to blame.

PCFA spokesman Peter Cliff said: "The complaints are predominantly about Eastern Europeans who have come over to England and, of course, there is a different culture over here.

"They are quite happy to eat carp where we would never dream of it.

"Many I have spoken to express genuine surprise that they cannot take their catch home.

"It is impossible to tell how many fish have been taken but it is potentially thousands."

He said theft could have a devastating-effect on fisheries. "Anglers want to go to waters to catch the biggest fish and if they aren't there then they won't go."

Mr Cliff said fisheries needed to take action to stop immigrants taking fish. Many have put up signs in different languages warning anglers to throw back their catches.

He said: "Some are talking about putting up CCTV while others are getting the message across to their regular customers who act as honorary bailiffs and report any theft."

Trevor Johnson, of Bedfordshire's Upper Ouse Fisheries Consultative Association, said warning signs were often ignored. He said: "Not so long ago two eastern Europeans came and offered me money for the fish I had in my keep net.

"It makes people angry when they pay thousands to stock somewhere with large carp, them someone catches them and sticks them on a barbecue."