Deer poaching has trebled in the last year, according to new figures, as gamekeepers said the problem was out of hand and agencies admitted they were tackling only a tiny proportion of cases.

The number of deer poaching incidents reported to the police in England and Wales rose to 335 in the 12 months to October, up from 106 the previous year. But wildlife and countryside groups say thousands of cases go unreported, largely because few believe the police would take it seriously, despite fines of up to £5,000.

"It is an increasing problem," said Gareth Cole, England's only dedicated poaching officer who took up the newly created post at the National Wildlife Crime Unit (NCWU) in September.

"The image of a poacher as a wily man taking a couple of pheasants for the family pot is certainly not true. Modern poachers are professional, organised criminals, who travel round the country and are often involved in other types of crime. Deer are killed by dogs in a barbaric manner and the poachers have no interest in the condition of the meat which they sell on the black market to the back doors of pubs or hotels," he said.

Higher unemployment rates due to the recession, a surge in the UK's deer population and improved record-keeping are believed to have contributed to the higher figures, with poaching intensifying in the run up to Christmas and the new year when there is an increased demand for game.

The British Deer Society believes up to 50,000 deer may be poached annually and Simon Clarke, of the British Association for Shooting and Conservation, agreed. With black market venison selling for about £1 a lb, deer poaching was worth up to £5m a year, he said. "Not all police forces report the figures to the wildlife crime unit. There is great disillusionment from gamekeepers about how police will respond to reports, so many do not bother. The police do not always know the right way to handle these calls. It depends who is in the control room on the night and who is sent out."

Most poaching is thought to take place in parkland, where access is easy, but in the countryside and on shooting estates dry stone walls are being destroyed, and diesel, quad bikes and other equipment taken. Farmers or gamekeepers can be attacked or intimidated.

Malcolm Cook, a gamekeeper for 30 years in Lancashire, said he had confronted 28 poachers since March. "They are becoming more brazen and now come during the day as well as night. None of them have been convicted. I feel like I am wasting my time and the police's time reporting it. [The police] don't seem to see it as an offence and it is only a matter of time before someone gets hurt trying to stop the poachers."

John Pratt, a gamekeeper in the Ribble Valley, said: "It is the same ones who keep coming back. They know the police don't do anything and they laugh at us. Or come back and break our window and slash our tyres. It is out of hand."

The NWCU maintains the problem is being taken seriously. Last month 50 officers arrested five men in East Sussex in connection with a suspected commercial deer poaching outfit. A large number of firearms, deer carcasses and venison were seized in an operation involving 50 officers.