Efforts are underway to remove tens of thousands of litres of diesel fuel from a sunken tug boat near Bella Bella on B.C.'s Central Coast, but local First Nations say the spill has already devastated clam beds in the area.

The tug, along with an empty fuel barge, crashed on rocks in Seaforth Channel near Athlone Island, just after 1 a.m. PT on Thursday. Both are owned by the U.S. company Kirby Offshore Marine and were heading south from Alaska.

Equipment that will allow crews to safely pump the remaining fuel off the sunken vessel was expected to arrive at the site on Monday 

But it's unclear how long it will take to empty the tug boat, said Jessie Housty, an elected tribal councilor for the Heiltsuk First Nation.

"It's an environmental disaster. It's a cultural disaster. It's affecting every facet of our community," she said of the spill, which is located in the environmentally sensitive Great Bear Rainforest.

Despite containment efforts around the tug, diesel continues to spread, Housty added.

"We are still seeing the sheen that initially escaped spreading. It's getting closer, actually, to the community of Bella Bella now." she said.

"Productive clam beds for the most part have been compromised by this situation which is, unfortunately, going to have the effect of making it difficult for a lot of members of our community to get through Christmas."

Fisheries and Oceans Canada has closed the shellfish harvest in the area over fears of contamination.

"There have been reports, obviously, of a sheen on the water and some of the diesel reaching the beach," said agency biologist Elysha Gordon.

Samples are being taken at beaches in the area, but until those samples are tested, it's not clear how long the closure will remain in place, she said.

Criticism of emergency response

The Heiltsuk Nation and B.C. Premier Christy Clark are among those who have been critical of the spill response.

Federal Fisheries Minister Dominic LeBlanc addressed the issue in Ottawa.

"I think the Coast Guard, in difficult circumstances in the middle of the night, did a terrific job, most importantly ensuring there was no loss of life," LeBlanc said.

"We have some specific ideas of things that we can do to improve, particularly around environmental response on all of the Canadian coasts, but certainly we understand the concern of British Columbians."

The Heiltsuk said their efforts to interview crew members on the Nathan E. Stewart and to obtain information about the incident from the company or Transport Canada have been unsuccessful.

The First Nation said it plans to fundraise to carry out its own investigation and fund more clean-up efforts.

Transportation Safety Board investigates

The Transportation Safety Board said it has started interviews with the crew of the Nathan E. Stewart to determine how it, and the empty fuel barge it was pushing, ended up on the rocks.

The vessels will be examined after they have been salvaged, said Glenn Budden, a senior marine investigator for the TSB.

"The salvage plan seems to be solid,"  he said. "So we have been focusing on the crew."

Vessels operated by Kirby Offshore Marine have also lost a pilotage exemption from the Pacific Pilotage Authority because of the incident.

U.S. vessels that are under 10,000 gross tonnage, such as the Nathan E. Stewart, are often allowed to operate without a local pilot on the West Coast of Canada, if the crew meets a minimum standard of experience and licensing.

But until the circumstances of the grounding are known, that exemption has been suspended, said Kevin Obermeyer, CEO for the Pacific Pilotage Authority.

"The cessation of the waiver will be in place until we can clearly identify what happened and why."

In the meantime, Kirby vessels will have to either avoid routes that require pilotage or pay for the services of local pilots, he said.

Western Canada Marine Response Corporation, Transport Canada, Environment Canada, Fisheries and Oceans Canada and B.C.'s Ministry of Environment are all working with the Heiltsuk First Nation on the spill response.

With files from Greg Rasmussen