A fish farmer from Wales is suing the Environment Agency for £2 million because otters ate all his carp.
Brian Dodson, 60, from Bangor, is suing the government after otters ate his shoal of 22,000 prized carp, worth a total of £250,000.
He has launched the legal case at the High Court in Cardiff, claiming the agency is guilty of a breach of duty for encouraging otters to breed on a river close to his fishery.
Dodson says the agency, which is primarily concerned with rivers, flooding, and pollution, illegally built otter holts to encourage them to settle on the River Cegin, which is just two miles from his Waen Wen Fishery in Tregarth, north Wales.
The Environment Agency denies this claim and its lawyer Louis Brown told the court that its aim was to "protect and enhance the environment" on inland waterways.
"The agency did not construct otter holts on that site or anywhere else, or increase food stocks to encourage otters," he said.
"Mr Dodson's claim is ill-conceived. The agency's work on the river Cegan was to clear part of it of rubbish."
However, the farmer says the 1995 Environment Agency Act means the agency was there to conserve the environment, not to enhance the habitat of animals.
Dodson said an environmental impact study was not carried out before otters were encouraged to the area. He also said that had the agency told him about the holts, he would have built protective fencing for his carp.
This is set to be a landmark case for fishery owners, as many others have had similar problems with otters.
Otters ate Dodson's carp in 2009. He had gone to check his fish stocks but all he found was bones.
He was unable to sell his fishery and it was eventually taken off him by his mortgage company. He now lives off state sickness benefits.
The £2 million he is claiming is to cover the loss of income he would have gained from anglers using his fishery.
"I view what has gone on as unlawful - the agency has been putting in otter holts totally without authority throughout the country.
"The agency has no remit to enhance the habitat for otters such as building holts for them.
"I view what has gone on as unlawful - the agency has been putting in otter holts totally without authority throughout the country."
The hearing continues.