Lyme Bay fishermen have agreed to limit the amount of crabs, lobsters and whelks they catch in the first self-regulating agreement of its kind.

Their pioneering code of conduct comes after it was discovered some species had declined by up to 50 per cent – after the Government’s ban of scallop dredging and bottom-trawling in 90-square miles of Lyme Bay in 2008 saw a dramatic increase in other types of fishing.

A working group of fishermen, scientists, regulators and the Blue Marine Foundation charity drafted the memorandum of understanding (MoU) which came into force on Monday.

The MoU limits the number of pots put down by any one boat.

The group wanted to find a way of reconciling the needs of the environment and local fishing industry and this is the first example of self-regulation by local fishermen.

The experiment comes as the Government debates the designation of up to 127 similar zones to the one already established in Lyme Bay, which is Britain’s largest inshore marine protected area.

Under the new code the amount of gear used by any one fisherman will be restricted to 250 crab and lobster pots, 500 whelk pots and individual nets of 600 metres maximum.

This contrasts with up to 1,000 pots used by a few larger fishing vessels at present. Around 600 tons of whelks were caught in a year.

The Lyme Bay partnership also plans to fund a scientific study by the University of Plymouth, to find out just how much fishing Lyme Bay’s reefs can withstand.

This partnership also plans to fund environmental assessments of low impact fishing for all the major fish and shellfish species in the area.

Dependent on funding being secured, it is also hoped to establish a lobster hatchery.

Alex Jones, who represents a group of younger fishermen from the port of Lyme Regis, said: “The future has to be with fisherman and scientists working together towards a common goal of sustainability, protecting areas but still keeping the fishing communities going.”

Nigel Hill, also from Lyme Regis, added: “There is a real risk of it eventually being wiped out with nothing left for anyone.”

Crab and lobster fisherman Lewis Hodder, of Lyme, said: “What we do out of Lyme harbour is completely sustainable.

“This is more to stop the bigger boats coming in from elsewhere putting lots of gear down on our ground and messing our fish up.”

Mark Hix, Lyme Regis chef and restaurateur, said: “We need to support small fishing businesses like those that are involved with this project.”

Dave Sales, of the Commercial Boat Owners’ and Fishermen’s Association in West Bay, said: “Sustainability provides a future for the fishermen.”

Jim Portus, chief executive of the South Western Fish Producers Organisation and secretary of South West Inshore Fishermen’s Association, says of the Working Group’s report: “Trawlermen do wish for a sustainable, workable multi-use strategy for this iconic area and through their association, SWIFA, they will continue to engage with the working group.”