PORTLAND — Canadian lobstermen set up blockades at factories, and six to eight plants in Atlantic Canada stopped processing operations Tuesday amid intensifying protests demanding that the plants not accept low-priced Maine lobster.

Last week, lobstermen blocked trucks from delivering lobsters to plants in Shediac and Cap-Pele, New Brunswick. The blockades have raised fears among Maine lobster dealers that ship tens of millions of pounds to Canadian processors annually.

Fishermen on Tuesday blockaded more processing plants, claiming the low price of Maine lobster is driving down the price of Canadian lobster. By late Tuesday, four to six processors in New Brunswick and at least two in Prince Edward Island had agreed to suspend operations for at least two days, Maine Marine Resources Commissioner Patrick Keliher said.

Maine lobster dealers now are scrambling to find processors elsewhere in Canada who will take their product. Dealers are having to slow down their lobster purchases from lobstermen, potentially creating even more of a glut of lobster and driving down prices even more, Keliher said.

"It's too soon to call it a crisis, but it's a serious situation," he told The Associated Press. "Right now, from my perspective, it's potentially going to get worse."

Canadian lobstermen say the low price of Maine lobsters is driving down the price they'll get for their catch when their seasons open. Videos and photos show large groups of protesting Canadian lobstermen dumping Maine lobsters in the street and holding signs saying things like, "No More U.S. Lobster."

A deal reached last week among New Brunswick Fisheries Minister Michael Olscamp, processing plants and the Maritime Fishermen's Union called for New Brunswick lobstermen to be paid at least $2.50 a pound for lobster that was going to be processed and $3 a pound for product for the live market.

But fishermen told the Canadian Broadcasting Corp. that they need at least $4 a pound when their season opens. Olscamp did not return calls on Tuesday.

Canada's federal Department of Fisheries and Oceans announced Tuesday that the start of the lobster-fishing season in southeastern New Brunswick was pushed back four days, until Monday, at the request of fishermen's associations.

In Maine, state officials and lobster dealers are concerned the blockades will back up lobster supplies on the U.S. side of the border, creating even more of an oversupply that already has driven down prices to 20-year lows.

Maine Gov. Paul LePage said he's been working with New Brunswick Premier David Alward seeking a solution.

"I conveyed my concerns about the effects this could have on Maine's fishing industry, which provides a mutual benefit for both countries," LePage said in a statement.

U.S. Sen. Susan Collins expressed her concern to the U.S. ambassador to Canada, David Jacobson.

It's estimated that more than half of Maine's annual harvest — last year's catch topped 100 million pounds — is shipped to Canadian processors who turn the whole lobsters into meat and frozen products. There are about two dozen processors in Canada, while Maine has only three processing plants of any size.

Canada's Department of Fisheries and Oceans said Fisheries Minister Keith Ashfield is monitoring the situation and is prepared to make changes to fisheries management practices that fall under federal jurisdiction if needed.

Fishermen in Maine have been receiving as little as $2 a pound for their catch because of a glut brought on by a strong early season harvest.

Consumer prices have fallen as well, with some retailers in the Portland area selling small, soft-shell lobsters for under $4 a pound. Larger and hard-shell varieties sell for higher prices.