The source, composition and quantity of the toxic fuel that spilled out into the waters of English Bay in Vancouver Wednesday afternoon is still unconfirmed.

In a news conference Thursday afternoon, Roger Girouard, head of the Canadian Coast Guard western region, said that the spill was being treated as either bunker fuel or raw crude in a "worst-case scenario" until test results came back.

Residents were being warned to avoid the beaches on both sides of the bay on one of the sunniest days of the year, and to keep their dogs leashed and away from wet sand as a cleanup operation continues.

Girouard said that two large patches of the spill had been spotted moving toward the North Shore of the city, and had been collected immediately. No large slicks had touched the shoreline, he said, but there was "sheen material and some black tar balls" on the beach.

Fourteen hundred litres of the spill had so far been collected, he said, with a rough assessment of a total 2,800 litres present in the water.

English Bay spill

The spill occurred in Vancouver's picturesque English Bay. (CBC)

That amount was "above the norm" but not "catastrophic."

The source of the spill remains unconfirmed, as crew of the grain ship Marathassa, which sat in the middle of the spill, denies they released any material, Girouard said, noting that lawyers are involved.

"We can't definitively say it came from that vessel," he said. "The master says they are not the source of the oil."

Girouard said that from an operations perspective, the response had gone "according to doctrine," but he acknowledged that communications to the City of Vancouver and its residents "could have been better."

Anyone concerned about possible contamination, or who has other questions and concerns about the spill, is encouraged to call a hotline number on 604-873-7000.

'It's sad'

Herman Dreier ran down to the beach at the foot of Denman and Davie Streets as soon as he heard what had happened.

"We're down here every morning," he said. "It's sad. Sad. I'm sorry, but you [can see] wildlife swimming around in this crap."

The Canadian Coast Guard said it was notified about the spill generated from an anchor point in English Bay at about 5 p.m. PT Wednesday.

Miriam Van Roosmalen, the coast guard's B.C. regional director, said Thursday morning that it became quickly apparent that the size of the spill was larger than initially reported, and a cleanup operation was launched immediately.

The suspect vessel is now boomed off, she said. "It would seem that the source has been contained."

Vancouver Coun. Geoff Meggs said Port Metro Vancouver took 13 hours to inform the city of the spill.  

"We will want to find out more about the gap between the spill itself and the notification of our city resources," he said. "We provide fire and police support to the port."

The Vancouver Aquarium's Marine Mammal Rescue Centre is on standby, said Peter Ross, who runs the ocean pollution research program.

"First and foremost, we're going to be looking for marine mammals on the water. We would be concerned if an endangered species, like our cherished southern resident killer whales might enter English Bay."

Ross said there are 25 species in the area, including fish and seabirds that could be at risk

The coast guard has contracted the Western Canada Marine Response Corporation to aid in the cleanup, using long orange booms on the surface of the water to contain the spillage.

With files from Farrah Merali, Steve Lus, Meera Bains, Terry Donnelly and Kirk Williams