The Heiltsuk Tribal Council threatened last week it would not allow the fishery to open this year because it found stocks were too weak and need time to rebuild.
But on Sunday, the federal Department of Fisheries and Oceans opened a herring-roe seine fishery in Spiller Channel, near the community of Bella Bella, prompting an angry response from the band.
Heiltsuk Coun. Reg Moody declared the band will intervene if it discovers boats returning to the area. He also requested that federal Fisheries Minister Gail Shea visit to see what his First Nation is facing.
"We plan to put lines (ropes) in the water, to just disrupt them when they're trying to fish," said Moody, who is also chairman of the Central Coast Regional District. "There's ways to do that peacefully."
He said the issue is not new and pledged that until there is reconciliation, there won't be peace on the water.
"I think we've been reasonable. We've been willing to work together."
But Greg Thomas, chair of the Herring Industry Advisory Board, said Shea's decision was based on strong science, and a total of 2,902 tonnes of herring was allocated.
Of that, he said, 1,542 tonnes went to First Nations and 1,270 tonnes to the commercial roe-herring fishery.
He also said there would be no area for the industry to fish if it followed "no-go areas" established by First Nations.
"The industry is trying to find a compromise so that they can have a successful fishery and so can the First Nations."
Thomas said he hopes civil disobedience can be avoided, and there was "no negative impact" from a protest on Sunday evening.
"The industry will just attempt to work with the First Nations and avoid conflict on the grounds," he said.
Fisheries officials said in an email they were unable to provide an interview. Last week, spokesman Dan Bate said the department opens roe fisheries in consultation with industry advisers on the ground, and also maintains ongoing dialogue with 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 said.
"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."
Moody said the First Nation has tried unsuccessfully to negotiate a memorandum of understanding on the issue with the industry and federal government.
He said the band is so worried about further stock depletion it's holding off from leasing two of its own gillnet licences.
Heiltsuk Chief Coun. Marilyn Slett estimated commercial boats fished about 680 tonnes between late Sunday afternoon and Monday morning alone, the time since the fishery opened.
"I believe it's just to make a point around fishing for the sake of fishing," said Slett.
"We're really concerned about the stocks and how fragile they are. Overfishing and management of the herring stocks can lead to another collapse — could lead to extinction of that species — and that's just something that we can't bear."
The Heiltsuk Nation is the latest aboriginal band to speak out in a long-standing battle against the reopening of commercial herring fisheries with warnings of perilously low stock numbers.
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.
— Written by Keven Drews in Vancouver