Canada is investigating incidents of U.S. patrol boats straying into waters it claims as its own and approaching Canadian fishing vessels.
LeBlanc said concerns about illegal immigration at the border between the U.S. and Mexico should not be applied to the Canada-U.S. border.
The question of jurisdiction flared up recently after the Grand Manan Fishermen's Association said a Canadian vessel had been stopped by USA border patrol while fishing in the waters near Machias Seal Island in late June.
The waters that surround the island, at the mouth of the Bay of Fundy, in the Gulf of ME are also disputed.
Global Affairs Canada - describing the area as Canadian territory - said this week it is investigating the incidents.
He has also bolstered border security in the northern frontier with Canada, and the American Civil Liberties Union said US police had been setting up more checkpoints on roads leading to the Canadian border to check people's citizenship.
According to a statement from the Grand Manan Fishermen's Association obtained by CBC News, the association said it believed the situation was part of a "regular exercise being conducted along the us marine border".
The U.S. Border Patrol also said that it has stopped and boarded 21 Canadian vessels this year in contested waters in the Bay of Fundy, and has no goal to stop.
"Houlton Sector Border Patrol has conducted operations in the past in this area and will continue to conduct operations in the waters off the Coast of ME in jurisdictional waters of the United States", Stephanie Malin wrote in an email.
The boats were stopped while fishing near Machias Seal Island, an area where both the United States and Canada claim jurisdiction.
Doucet said Wednesday that the "heavily armed" Border Patrol agents were looking for undocumented immigrants, but that the fishermen were just "doing their job".
In a written statement, the fisherman's association said American and Canadian fishermen have jointly fished the 102-square mile area for years.
Ties between Canada and the United States have been strained since President Donald Trump slapped tariffs on Canadian steel and aluminum, citing USA national security, with Trump calling Canadian Prime Minister Justin Trudeau "very dishonest" and "weak" after a spat at the G7 meeting in Quebec last month. The island and surrounding waters are claimed by both the US and Canada, though boats from both countries have fished the waters comfortably for years.
The federal agency did not confirm how many vessels this had happened to.
While the bulk of the Border Patrol's operations focus on the United States' southern border, the agency maintains a modest presence near the northern border with Canada.
The dispute has fueled tension between American and Canadian fishermen over the years, as the waters around the island are especially important lobstering grounds.
The State Department did not respond to a request for comment. But both Canadian and American fishermen said they noticed increased activity in harbors and in the Atlantic in early June.
"I wouldn't call it unprecedented or say that the fishermen were harassed", said John Drouin, 53, a member of the Maine Lobster Advisory Council who lives in the coastal town of Cutler, about 10 miles from Machias Seal Island.
The reports come as relations between Canada and the United States are at their lowest point in recent memory.
"What caused that? You'll have to talk to border patrol".
"If the Canadians want to use the term harass, they have been harassing us for years", Drouin said.