Scientists have discovered a new breeding ground for porbeagle sharks off Canada's East Coast, giving hope to a species whose numbers have been steadily slipping around the world.

A research team located the mating area on Georges Bank earlier this month after hearing reports from fishermen that they were hauling up the large, blue-grey sharks in their nets.

Steve Campana, a marine biologist who specializes in the species, said the find makes it only the second known breeding ground in the Northwest Atlantic for the fast, fierce-looking shark that can reach almost four metres in length.

"This is really good news," Campana said from his office at the Bedford Institute of Oceanography in Halifax where he heads the Canadian Shark Research Laboratory.

"To have a second mating ground where they actually seem to be more abundant is great news. … It is key toward conservation efforts."

Researchers set two lines near the northern edge of Georges Bank, a rich scallop and groundfish fishing ground almost 500 kilometres from the Nova Scotia coast. Within hours, he said they pulled in 21 sharks — 19 of which were large, mature female porbeagles that weighed 200 kilograms each and were about two metres long. Campana suspects there might be hundreds, if not thousands, of sharks in the area.

Tagged with satellite monitors

Before returning them to the water, the scientists tagged the fish with satellite monitors so they can track their movements and identify where they give birth.

Until now, scientists knew of only one breeding ground for porbeagles off Newfoundland and Labrador's southern coast. The area was closed to directed shark fishing shortly after it was identified as a mating area.

Campana said Fisheries managers are now reviewing the latest find to determine whether the area should be closed to shark fishing to stave off another collapse in the population.

"The discovery of the second mating area which is totally unregulated is of concern," he said.

"Nobody wants to fool around with this one. We want them to recover and everything we've seen so far indicates they are, but it's going to take a long time."

Patrick Gray of the Atlantic Shark Association said he would recommend to his members that the newly found area be closed to shark fishing, to help ensure the species is around in the future.

"We're possibly looking at closing this area on Georges Bank," he said from Sambro, N.S., the base for most of the province's shark fishermen. "We're not going to be known as the eliminators of any stock.… Maybe by shutting it down, we can help it rebuild all the quicker."

The porbeagle fishery is worth an estimated $2 million annually on the East Coast, with 90 per cent of it going to markets in Boston.

The porbeagle population reached dangerously low levels in the mid-1990s, when quotas soared to 1,500 tonnes in the Atlantic region versus today's catch allowance of 185 tonnes.

It's estimated there are about 190,000 porbeagles in Canadian waters — putting the stock at about one-quarter of its level in 1961 when the fishery first started.