PORTLAND, Maine — Tensions between lobstermen in Maine and Canada are boiling over in a dispute caused not by too few lobsters, but by too many.

A huge and potentially record-breaking haul of crustaceans in Maine and Canada this year has caused a market glut and a crash in wholesale prices. Fearing for their livelihood, Canadian fishermen in the past few days have angrily blocked truckloads of Maine lobsters from being delivered to processing plants in Canada that turn out lobster products for U.S. supermarkets and restaurants.

Unless something is done to prop up the price of lobster, “we’ll go down the hole,” warned Eugene Robichaud, a fisherman in Richibucto, New Brunswick.

The blockades have brought Canada’s lobster-processing industry to a near-standstill, put thousands of employees out of work, sent shockwaves through Maine’s lobster industry and led to calls for Secretary of State Hillary Rodham Clinton to intervene.

Portland lobsterman Greg Griffin said he has been getting a paltry $2.35 a pound for his catch, a dollar less than a year ago, and he fears the blockade could drag prices down even more.

“At what point is going out and bringing in lobster no longer viable?” he asked.

The dispute isn’t expected to have any immediate effect on lobster prices in the United States. National restaurant chains such as Red Lobster that buy processed lobster typically make their purchases and determine their menu prices far in advance.

But the troubles shine a light on the workings of the lobster business in North America’s cold northern waters, and the way Maine’s industry and Canada’s depend on each other.

While much of the catch from both countries is sold live, a big share is canned, turned into frozen lobster tails or otherwise packaged. An estimated 35 to 50 per cent of Maine’s annual catch is shipped to Canadian processors. Canada has more than two dozen lobster processors, about half of them in New Brunswick. Maine has only three plants of any size, and they handle only a fraction of what is processed in Canada.

Because of so much lobster on the market, fishermen have been getting barely enough to cover fuel, bait, boat payments and other expenses.