The spawning of surf smelt, a miracle of nature that largely unfolds unnoticed on Vancouver's beaches, was under way when a freighter accidentally spilled 2,800 litres of bunker fuel in English Bay.
Now, three weeks later, the deadly impact of that oil on smelt embryos is slowly coming into focus under the microscope of Ramona de Graaf, a marine biologist who is a leading expert on the small herring-like fish that live and die on the city's shoreline without most people knowing they exist.
"These embryos are one millimetre in size. They are very tiny. They are on the surface of the beach," said Ms. de Graaf, who has been retained by the Canadian Coast Guard and the ship owner to assess the damage of the spill. "We're talking micrograms of petroleum products per litre [of sea water] is all that's needed to kill these embryos."
She is in the early stages of collecting samples of sand and gravel from 10 spawning beaches around Vancouver, where millions of tiny eggs are laid by surf smelt each spring. Surf smelt, once so numerous they supported a commercial fishery that harvested hundreds of tonnes annually, have grown increasingly rare, but still play a vital role in the marine food web, providing forage for many species and still supporting small commercial and recreational catches. During spawning runs they tumble ashore on waves, laying eggs in seconds before vanishing again into deeper water. Females carry up to 30,000 eggs, which they deposit in repeated events. Beaches can contain up to 1,000 eggs per square metre of sand.
In an interview, Ms. de Graaf said the spill, which hit several beaches, may have killed some of the eggs. Embryos die naturally, so to determine what mortality might be due to the spill she is comparing samples from fouled beaches with beaches that weren't contaminated.
"I'm still processing all the data. I've got all the samples but I have to take them tablespoon by tablespoon under a microscope and pluck out all the embryos," said Ms. de Graaf. "I can tell you briefly that there's a difference between beaches that were not affected by the oil and beaches that were affected by the oil as far as the survivability of the embryos."
Ms. de Graaf said she can't release any findings until her research is completed, but she sounded worried by what she's seeing.
"I just can't tell you," she said when asked how many smelt embryos might have perished. "But I think you can hear it in my voice."
She was critical of the Department of Fisheries and Oceans for not closing a recreational smelt fishery, saying the fish should be protected until the impact is known.
"Taking out the reproductive adults right now when the embryos have probably failed because of the oil spill [isn't cautious]," she said.
In an e-mail, DFO spokesman Dan Bate said a long-term monitoring program, which will include input from the Tsleil-Waututh Nation, is being undertaken under the leadership of the Canadian Coast Guard.
Mr. Bate said while a crab fishery was closed in the wake of the spill, the recreational surf smelt fishery remained open because "there was no evidence of a potential health risk related to their consumption."
Several days after the spill, the Coast Guard reported that 80 per cent of the oil had been recovered. But Anita Burke, an oil-spill response expert who worked on the Exxon Valdez cleanup, said rarely is more than 15 per cent of any spill ever recaptured.
"My experience tells me … they captured 80 per cent of what they could see, but how much sank?" she said.
Ms. Burke, who is speaking Wednesday night on a Simon Fraser University panel at the Morris J. Wosk Centre for Dialogue, said the impact of the Marathassa spill will be felt for years on Vancouver's beaches because oil drifts suspended in the water column, or sinks to the bottom only to resurface because of wind or tidal action.
Editor's note: A previous version of this story said Ramona de Graaf was hired by the Tsleil-Waututh First Nation to assess the damage of the Vancouver oil spill. In fact, she has been retained by the Canadian Coast Guard and the ship owner.