Debbie Thompson, who fishes out of Richibucto, says the fishermen fear that the market is being flooded with cheap lobster from Maine.
She says New Brunswick fishermen can't afford to match the American prices.
The lobster season opens next week in the Northumberland Strait and Thompson says fishermen are considering not heading out.
The truck was leaving the Shediac Lobster Shop when it was surrounded by the fishermen.
RCMP Cpl. Chantal Farrah says the fishermen are also demonstrating in nearby Cap Pele and police officers are on hand in both places.
She says people have a right to protest but are being told to keep the peace.
Farrah says there have been a number of incidents of mischief.
She would not provide any details, but she said the police are looking into the incidents.
(News 91.9, The Canadian Press)