A substantial fall in the price of Maine lobsters has led to a cross-border dispute, as processing plants in Canada anger local fishermen by importing the cheaper catch from their US counterparts.

Frustration over the influx of cheap lobster has boiled over in New Brunswick in recent weeks, leading to ugly scenes as hundreds of lobstermen have taken to the streets in order to force delivery trucks to turn around.

Such picketing has brought the Canadian lobster meat-processing industry to a near standstill, forcing thousands of workers to down tools and fracturing long-standing good relations with US fishermen.

Maine senator Olympia Snowe felt compelled earlier this week to ask US secretary of state Hillary Clinton to intervene, warning that "acts of intimidation, violence, or coercion" could no longer be tolerated.

On Thursday, in an effort to take some of the heat out of the situation, a New Brunswick judge granted a 10-day injunction, banning lobstermen from blockading fish processing plants.

Christian Brun, executive secretary of the Maritime Fishermen's Union in New Brunswick, told the Guardian that his members were being encouraged to abide by the court ruling. "We are hoping that this can be resolved as soon as possible," he said.

Brun said that the among lobstermen anger had been building for years, as the price being paid to harvesters has been continually squeezed. Some lobstermen, he said, have been forced to the point of bankruptcy.

"The source of the problem is we have never seen so many lobsters," Brun said. "Over the last generation we have seen a tripling of lobster landings. And as an industry we have not been able to develop markets to the same degree as the increased catches."

The tipping point came with a bumper early crop of soft-shelled lobsters off the Maine and New Brunswick coast this summer. Warmer waters have increased the food supply, drawing crustaceans out into the open earlier than usual. Greater catch sizes in Maine have produced diminishing returns for lobstermen, with some reporting a drop in the off-the-boat price of up to 75%.

This has in turn seen a glut of cheap lobster meat being trucked north to processing factories in New Brunswick, prompting the province's lobstermen to take action.

"When local plants send the message saying, 'We are not sure we can buy your lobsters,' then the reaction is going to be quite visceral and it continues to be so," Brun said.

He added that many lobstermen in the province were at breaking point and felt the need to act. "Right now they have nothing to lose in protesting and blockading," he said.

Others think the direct action has gone beyond the acceptable. Matt McAleney, general manager of Maine-based New Meadows Lobster, said that "decades of great working relations with Canada" were unravelling because of "intimidation" by New Brunswick lobstermen.

He said: "If I'm a driver and just doing my job – a job I have done 100 times before – and then 400 lobstermen come out from everywhere and surround my truck, that seems pretty threatening to me.

"And we are not talking about 400 accountants – lobstermen are big dudes. Even if we are just talking about 50 against one driver, even Bruce Lee is going to feel intimidated in those circumstances."

The Maine Lobstermen's Association expressed "complete sympathy" with the financial woes of its Canadian colleagues but said it "strongly rejects" methods of protest that "disrupt, threaten, interfere with or otherwise impose obstacles on international commerce".

McAleney believes the situation will be resolved. "It will eventually work itself out, it always does," he said.

The 10-day injunction on protests ordered by authorities in Canada has allowed lobster meat-processing plants to continue operating. New Brunswick premier David Alward, who has described the recent action of fishermen in the province as "very unfortunate and unacceptable", said in light of the injunction that he hoped and expected to see "a more reasonable flow of lobster moving forward in the coming days".

But the impasse between processors and lobstermen appears to be far from over. Canadian lobstermen are demanding $4 per lb for their catch. So far processors have only agreed to $2.50 to $3. Maine lobstermen have reported that they are going as low as $1.35 per lb. At such prices, said fisherman Eugene Robichaud of Richibucto, New Brunswick lobstermen would go "down the hole".

Harvesters have complained that the return for a boatload of lobster has barely been enough to cover fuel, bait and other expenses. "If the price is too low, I'm going to have to pay to go fish," said Maurice Martin, also of Richibucto.

Such desperation is behind the protests outside processing plants in recent weeks. At the height of the blockades, lobstermen held up "No More US Lobster" signs and threw Maine lobster to the ground, calling it "garbage". But Canadian fishermen are also blaming their own government for not helping to prop up the price of their catch.

At one recent protest, lobstermen in New Brunswick rallied outside the office of fisheries minister Keith Ashfield, dumping large metal traps in the reception area.

With feelings running high, some see the 10-day injunction on blockades as an opportunity to take a step back and try to hammer out a deal.

"Right now we have a very small and tight space in which we have to find a solution," Brun said.