Fisheries and Oceans Canada says its science forecasts show herring abundance continues to support modest commercial harvest opportunities.
But the Heiltsuk claim herring stocks are on the verge of collapse.
"We don't trust DFO science"
"We don't trust the DFO [Department of Fisheries and Oceans] science." said Carrie Humchitt, the first nation's legal adviser. "It's very industry driven."
Humchitt says if a commercial fishing is allowed, the Heiltsuk will act.
"Our people are ready to mobilize and go out an protect our territory if we have to," he said. We're prepared to go out and protect our stocks."
"We think it's in very bad faith that the DFO is forcing us and other nations up and down the coast to go out and protect our fisheries."
In the meantime the first nation is working with its own team of advisers to establish its own measure of how Pacific herring stocks are doing in B.C. waters.
The Heiltsuk Nation is the latest aboriginal band to speak out with warnings of perilously low stock numbers in a long-standing battle against the reopening of commercial herring fisheries
The Haida Nation, in the remote community of Haida Gwaii, recently won an injunction to block a planned fishery, after joining two other First Nations to fight a fishery's reopening last year.
Expect police to intervene
Greg Thomas, the chair of the Herring Industry Advisory Board, says there are plenty of fish and if there is a Heiltsuk blockade, he expects police to intervene, but adds that the board prefers to negotiate an agreement.
Fisheries and Oceans Canada spokesman Dan Bate says herring roe fisheries are opened in local areas in consultation with industry advisers.
"DFO continues to have dialogue with the members of the local First Nations. DFO Conversation and Protection Officers have been speaking with commercial harvesters on the water to ensure the fishery is conducted in a sustainable and orderly manner," he wrote in an e-mail to the Canadian Press.
"DFO respects the right to protest, however we condemn any threat of violence or reprisal against those exercising their right to practice a lawful and sustainable fishery."