Scotland has introduced unprecedented fishing restrictions in a move to defuse a "prawn war" between west coast trawlers and their North Sea counterparts.

A severe shortage of prawn off Scotland's east coast this year prompted about 50 additional North Sea fishing vessels to head to the country's west coast, where locals feared their presence would deplete the prawn catch well before its conclusion in September.

Scotland's west coast, whose fisherman are limited in their time at sea under European Union's cod recovery plan, lodged complaints with Marine Scotland, saying the North Sea vessels were using up the region's time limits as they trawled for prawn.

The agency responded Friday by restricting for the first time the ability of North Sea vessels to trawl west coast waters.

The country's west coast fishery spans from Scotland's northern tip near Scrabster down to its border with England, across the Irish Sea from Northern Ireland.

Because of "an unprecedented shift of vessels that normally fish for prawns in the North Sea, where prawns have been scarce this year," the new measures had to be introduced, Fisheries Secretary Richard Lochhead said.

"I recognize the deep concerns of the industry over this issue, therefore its important government takes action to ensure west coast fishermen have their time at sea to catch their full prawn quotas this year," Lochhead said. "With the temporary measures we now have in place, I'm confident the usual fishing season can continue."

Under the new restrictions, the remaining 2012 fishing time for the west coast will be allocated to local vessels only, defined as boats with a record of more than 60 days fishing in the west during 2011.

The agency also said it would "consider the need for a managed closure of the west coast fishery" over the year-end holiday period and into early January, when minimal fishing activities take place.

"I want to emphasis that this issue has been caused by two factors -- firstly, the unusual scarcity of prawns in the North Sea that has lead to effort change; and secondly, this is not about quota availability but rather having the necessary days at sea to catch quota," Lochhead said.

"This illustrates the management difficulties related to the EU's flawed cod recovery plan," he added.

"We are satisfied with the government's compromise position," Western Isles Fishermen's Association Secretary Duncan MacInnes said in a statement issued to The Scotsman.

Scottish Fishermen's Federation President Alan Coghill added, "The prawn sector is an incredibly important part of the Scottish fishing industry, which needs full backing at all levels."

He said the "prawn war" underlines the need "for both the United Kingdom and the Scottish government to vigorously restate the case for reviewing and amending the Cod Plan before the end of 2012. The present situation is a prime example of a regulatory process which does not work and is likely to cause major economic and social problems across the industry from net to plate."

Another Scottish fishery executive, John Hermse of the Mallaig and North West Fishermen's Association, also bashed the EU's cod limitations, which he asserted "takes management of cod in areas such as the west coast to farcical levels."