Alien seaweed threat to lobster catch

Vincent Boutilier is worried about alien invaders.

But the lobster fisherman isn't watching the skies. On a clear day, he's more likely to be found looking over the side of his boat, scanning the seabed under St. Margarets Bay.

And what he's seeing down there makes him worried about the future of his business.

"We've only noticed the vegetation in the past three years," he said from his home in Hubbards. "It hasn't yet established itself in large amounts. So far, it's only covering five to seven per cent of the seabed, as far as I can tell." He's referring to codium, a type of spongy seaweed from Asia that's made its way to Nova Scotia waters by way of Europe.

Mr. Boutilier said it's too soon to say how much of an effect the interloper will have on the province's $300-million lobster fishery, but there are signs its growth may be crowding out the native plants that lobsters prefer.

"Last year, the lobster catch in Mahone Bay was down by one-third," he said. "Is it just a coincidence? It's hard to say."

But Mr. Boutilier isn't willing to sit around wondering.

He's taking his concerns to a two-day meeting of scientists, conservationists and government officials in Halifax this week.

Alien species are plants or animals from one part of the world that are introduced to another. With none of its natural predators to keep it in check, an alien species thrives to the point that it chokes out native species.

The most famous example of a recent invasion is the zebra mussel, an Asian species causing billions of dollars in damage to ships and pipelines in the Great Lakes.

Gretchen Fitzgerald, a Dalhousie biology student and one of the conference organizers, says our coastline is especially vulnerable to invasions, thanks to globalization.

Increased shipping means more foreign ships arriving in our ports, and that means more ships are dumping their ballast water off our shores.

"Not all water is created equal," she said.

"The water contains species that are not from here, and if they are introduced in an area where they are not naturally, they may be released from predation pressure."

Ballast water, the main means by which marine species hitch a ride across the globe, is a serious issue for marine biologists and conservationists, and a key topic of discussion at the conference.

According to the Ecology Action Centre, an estimated 4,000 species of fish, invertebrates and algae are moving around in ship ballast tanks every day. No one knows how many of them are entering Canada's coastal waters, where foreign ships release 50 million tonnes of ballast water every year.

Despite Nova Scotia's marine heritage, Ms. Fitzgerald says we have some catching up to do on the issue, citing Australia and British Columbia as places where the issue is taken more seriously.

"We have a very steep learning curve, but we are behind," she said. "We're not as progressive as we should be, considering how much people here care about the marine ecosystem."

Still she says there are signs the government is taking the issue seriously. In 1999, Transport Canada formed a committee to establish national guidelines for ballast management, and the federal department is co-sponsoring the conference.

That said, Ms. Fitzgerald said there's still room for improvement at the federal level.

"From what I've seen, the (ballast water) guidelines are voluntary," she said. "I would like to see the guidelines become regulations, so that ships are required to carry out these measures."

The conference concludes today.