Ecologists say the world's leading certifier of sustainably caught seafood would set a dangerous precedent if it put its stamp of approval on a Canadian fishery they say hauls in thousands of turtles and sharks every year.

Environmental groups across the country are lining up against the move to make the East Coast swordfish fishery the first large longline fishery in the world to be certified by the U.K.-based Marine Stewardship Council. An assessment of the fishery is in the final stages, and the council could soon put its coveted blue seal on swordfish products.

Shannon Arnold of the Ecology Action Centre in Halifax said the approval would undermine a movement that's worked for years to alter fishing practices that kill or maim sharks, turtles and dozens of other marine species as bycatch.

"This is greenwashing for consumers, and it's undermining the whole sustainable seafood movement," Arnold said in a recent interview.

"It's outrageous that this fishery would be certified as sustainable — you lose the meaning of what sustainable is because the bar is set so low."

The initiative has prompted groups like the David Suzuki Foundation and Greenpeace to argue against the certification, which has become a necessity for harvesters as major retailers vow to sell only sustainable seafood products.

The council assesses a fishery through an independent third party that evaluates the health of a stock, the effect of the fishing method on the ecosystem and how the fishery is managed.

The fishery has to meet standards set by the council and can have conditions attached to continue its designation as sustainable.

Jay Lugar, a Halifax-based spokesman for the council, said each fishery undergoes a rigorous evaluation process that can take a year and is subject to public scrutiny before it's certified.

"How a fishery is assessed is a very comprehensive and robust process and our standard is commonly viewed as a gold standard," he said.

Blow to loggerhead turtles

A key test for any certification is how the fishery affects other species, especially those that are endangered or threatened.

Scott Wallace, an analyst with the Suzuki Foundation, said certifying the longline swordfish fishery would be a major blow to northwest Atlantic populations of loggerhead turtles that get snagged in its lines.

American federal agencies have proposed upgrading the status of turtles from "threatened" to "endangered" under the U.S. legislation.

"Listing loggerhead turtles as endangered is a critical step toward protecting them from extinction," said Wallace.

"However, the U.S. proposal — and our chance to save these turtles — is being undermined by the operations of the Atlantic longline fishery here in Canada."

The Suzuki Foundation estimates that the Atlantic longline fishery for swordfish and tuna catch about 1,200 northwest Atlantic loggerhead turtles a year, with between 20 and 45 per cent of the turtles likely to die.

35 other species

The surface longline fishery works by setting out one main line on top of the water column, which can stretch about 40 kilometres with up to 1,500 baited hooks feeding off the main line.

It's left in the water for up to 24 hours and can catch any species attracted to the bait. Arnold said it can also snag about 35 other species that are thrown back.

Troy Atkinson, president of the Nova Scotia Swordfishermen's Association and the group that filed for the certification, concedes the fishing practice has a lot of bycatch but insists the majority are put back alive.

"The biggest part of those are released alive, so the impact isn't that great," he said in Halifax.

"Any industrialized form of commercial fishery typically catches more than the target species. You won't find one out there that doesn't and we're no different."

Atkinson argues that a leatherback turtle has never been hauled in dead, while three loggerhead turtles have died in the gear in the last 10 years.

But Arnold said fish scientists have estimated that about 35,000 blue sharks die after being tossed back.

Environmentalists charge that the council has certified fisheries that later collapsed or were in poor health, like British Columbia salmon, and that it doesn't follow up on its own conditions.

There are about 66 certified fisheries and 120 in assessment, with many lining up as retail giants like Wal-Mart and Loblaws commit to sell only sustainable seafood by 2013 or earlier.