Federal fisheries officials don't want to make that mistake again, and so marine biologists are crunching data from Canada's first "census" of a shark population with the porbeagle as its focus.

The stakes are high as sharks globally are threatened by exploitation for their meat and fins. Some conservationists say Canada's porbeagle fishery should be closed though government scientists maintain it appears sustainable at current levels.

Eastern Canada has already witnessed the spectacular collapse of its once-teeming cod fishery, and scientists understand their margin for error is thin.

"We do not want sharks to go the way of the cod. This is the first time Canada has ever done a survey for any shark in our waters," said Dr. Steven Campana, head of the Canadian Shark Research Laboratory at the Bedford Institute of Oceanography.

"It was more like a census as it was like an attempt to count how many sharks were in our waters," he told Reuters.

The survey took place over about a six-week period and ended in mid-July. During that time, biologists went out on commercial fishing boats up and down the east coast of Canada.

"They all fished for sharks using scientific methods or identical methods -- they all used 600 baited hooks per day," said Campana.

"And then the biologists would count, examine and measure every shark that was caught. The fishermen were allowed to keep some of the sharks but they volunteered to release the mature females and the young juveniles," he said.

About 95 percent of the sharks caught were porbeagles.

The mature females had satellite tags attached to them so scientists can track their movements and monitor other aspects of their life over the next six months.

"Preliminary indications are that the survey was successful, the fishermen caught lots of sharks in areas where we expected them to catch them. But they also caught sharks in areas where we didn't expect them," Campana said.

"In total, close to 1,000 sharks were caught in this survey and at this point we estimate there are about 190,000 porbeagles out there off Atlantic Canadian waters," he said.

Additional analysis needs to be done on the data, and more conclusive findings are expected later this year. Future surveys also will be carried out in June to maintain a consistent research pattern.

TO FISH OR NOT TO FISH?

The current quota for porbeagles is 185 metric tonnes a year. Campana said any indications from future surveys that this amount was unsustainable would lead to the closure of the fishery.

Some scientists argue that even that quota -- slashed from up to 1,500 tonnes a few years ago -- is too high as porbeagles are slow reproducers even by the sluggish standards of the shark world.

"A quota is a risky approach because porbeagles are exceptionally slow growing and we should err on the side of caution. They are not biologically equipped to take heavy fishing," said Sonja Fordham, director of the shark conservation program for the Washington-based Ocean Conservancy.

There are also concerns about porbeagle being harvested as "by-catch" from other legal fisheries.

The United States is considering making the porbeagle a "prohibited species" that would make it illegal for fishermen to target it.

The World Conservation Union considers the shark to be endangered off North America's east coast, and it is seen as critically endangered in European waters where it basically has no protection.

Porbeagles grow to about 6.5 feet (2 metres) in length and are not considered a threat to humans.

Still, bearing what some might regard as a sinister resemblance to its close but much larger relative the great white, the porbeagle seems an unlikely poster boy for green causes.