A long-standing boundary dispute between Canada and the United States has become more complicated because of changes in the lobster fishing industry.

The two countries have disagreed for decades about who owns tiny Machias Seal Island and the lucrative 700-square-kilometre lobster grounds around it.

In the past, local fishermen based in Cutler, Maine and Grand Manan Island, New Brunswick have feuded over the area, but have been able to sort out their differences informally.

Now, New Brunswick's fisheries minister and one Maine industry representative say local solutions are more difficult with non-Grand Manan Canadians acquiring licences to fish in the area.

"Some of the boats coming over from Nova Scotia have upped the ante a little bit," says Fisheries Minister Rick Doucet, whose constituency includes Grand Manan.

Kristan Porter, a Cutler fishermen and board member of the Maine Lobstermen's Association, agrees, saying non-local Canadian owners who acquire licences but don't fish themselves don't have the same rapport with their Maine counterparts.

The Canadian flag flutters in the breeze by the lighthouse at Machias Seal Island. (The Canadian Press)

"I have much better luck working around and working with [Canadian] guys who own those traps sitting beside mine, who don't want to be tangled up and have a conflict," he says.

"But when you've got guys from Nova Scotia who don't have a penny in it, or guys even from Grand Manan now, where the guy running the boat doesn't have a penny in it, it's really no skin off their nose."

Canada and the U.S. both say they own the so-called "grey zone" around Machias Seal Island, and have argued over it since 1971 with no resolution.

There have been tensions before, including incidents of trap lines being cut loose, but no full-blown conflict.

Traditionally, local fishermen from both communities have been able to strike informal agreements to share the fishery.

But in recent years, at least one Nova Scotia processor as well as aboriginal bands exercising their rights under the Supreme Court of Canada's Marshall decision have acquired licences that were once part of the Grand Manan fleet.

New players

Those new players don't have as much of a stake in cooperating with the Maine fishermen, Porter says, and it means the Canadians no longer speak with a single, unified voice.

"They're all Canadians to me, the guys who have never been there. But when you've got Canadian guys feuding with other Canadian guys, on top of us — that's a flare-up, too," he says.

Grand Manan fishermen resent the Nova Scotia move into their traditional area, and successfully lobbied Ottawa for a freeze on the transfer of any more licences belonging to Grand Manan fishermen to off-island owners.

But those who did get licences are using them, including Steven Corkum, the president of Nova Scotia-based Yarmouth Sea Products.

Corkum says his purchase of a licence and boat two-and-a-half years ago was perfectly legal under Canadian fisheries law, and enables him to hire a crew to catch lobster in Zone 38. Canada considers the grey zone to be part of that area.

New players in the lobster fishing waters near Machias Seal Island are intensifying a historic boundary dispute between the United States and Canada. (CBC)

High lobster prices make it too lucrative to resist, he says. "If it's good, people are going to come."

He says the Maine fishermen are simply trying to protect their existing advantage.

"Ever hear about the gold rush out west?" he says. "Everyone would have liked to have been the first one there, too."

Corkum says the latest tension doesn't amount to much. "We've had no problem with anybody, really," he says.

No one from the Grand Manan Fishermen's Association could be reached for comment.

Porter agrees that what's reviving the dispute now is media attention, thanks to a story last week in the Boston Globe about the dispute, the only Canada-U.S. boundary disagreement that inv olves a piece of land.

"The only flare-up, more or less, is the press," he says.

When Canada closed its fishing zones to foreign fleets in 1971 and used Machias Seal Island as a reference point to define those zones, the U.S. objected, saying it had never conceded Canadian ownership of the island.

But the roots of the disagreement date back much farther, because the island is not mentioned in any of the treaties signed over the years to define the boundary between British North America — later Canada — and the U.S.

Canada has argued that Machias Seal Island is covered by the definition of "Nova Scotia" in a 1621 land grant by the King of England.

The U.S. says the wording of that land grant was negated by subsequent treaties, including a 1783 agreement that awarded islands within twenty leagues of the American coast to the U.S.

Winner could take all

In 1984, Canada and the U.S. sent their competing boundary claims in the Gulf of Maine to the International Court in The Hague, but decided to exclude Machias Seal Island from their arguments.

Experts believe they left it out because each country feared the court might balance out a win for one country by awarding the more lucrative Georges Bank to the other.

There have been discussions since then between the two countries on how to sort out the lobster dispute, but so far there has been no agreement.

New Brunswick established a lighthouse on Machias Seal Island in the 1830s and Canada still keeps it staffed year-round today as an assertion of sovereignty.

In a written statement, the Canadian government says it is committed to ensuring the Zone 38 fishery is "orderly, sustainable, safe and fair."

The Department of Fisheries and Oceans says it will "take action" against those who violate fishery regulations, threaten safety and conservation, and interfere with legitimate fishing.

"We have arrangements in place with the U.S. regarding enforcement," the statement says without including details.

It says the two countries are working together "to ensure effective enforcement and to develop a coordinated management approach for this area."