OTTAWA — One of the world's leading underwater explorers is asking Canada to support an international moratorium on bottom trawling on the high seas.

Sylvia Earle, a U.S. biologist who has led more than 60 deep-sea expeditions, said Tuesday that international momentum is building to stop a highly destructive fishing technique.

Bottom trawlers drag heavy gates and traps over the ocean floor, destroying virtually everything in their path to harvest a few valuable species such as shrimp and orange ruffie.

"Imagine using a bulldozer to catch song birds for food -- that's what it's like,'' said Earle, who has watched the process from the ocean floor.

"Before trawling, you see eyes that look out from all the little crevices, crannies, burrows and little hills, all sorts of stuff that lives there.

"After a trawler has gone by, it looks like a superhighway, it's just flat. Nobody's home. A few fish may swim in and out but the residents, those that occupy the substrate, they're just smothered, they're crushed. It's like paving them over.''

Earle said the international community has successfully curtailed whaling and driftnet fishing, showing it is possible for countries to co-operate for ocean conservation.

"Most nations are out of whaling. It's a very few that continue to condone it. So there's hope. I've seen populations recover, or begin to recover, like the gray whale.''

Under the previous federal government, Canada did not support a moratorium on high seas bottom trawling. That could change under the Conservatives.

"I am not one to pussyfoot around or keep us on the fringes,'' said Fisheries Minister Loyola Hearn in an interview after meeting with Earle.

Hearn said he basically agrees with Earle's views on bottom trawling. "It does damage to the stocks and it does damage to the habitat.''

But he was not ready say whether he will support a high-seas moratorium at UN talks next month.

"We need to move carefully in that there are countries, there are companies, there are people that depend heavily on that and some species that can perhaps only be caught that way.''

Canada permits bottom trawling in its domestic waters but Earle said she is primarily concerned about the high seas where there is no government oversight or regulation.

"It only takes a tiny fraction of individuals to behave irresponsibly to destroy the usefulness of the freedom of the seas for anyone.''

She said most of the high seas have not yet been subject to bottom trawling, which makes rapid action critical.

"The deep sea is one of the areas where we have a chance to get it right.''