VICTORIA — B.C.'s endangered population of southern resident killer whales face serious health issues from the exhaust emissions of pleasure and whale-watching boats, a study by a Victoria zoologist has found.
Over 2 1/2 years, Cara Lachmuth studied vehicle traffic and atmospheric conditions near the endangered southern resident killer whale population, which currently has 87 members.
What she observed is "worrying," Lachmuth said in an interview Thursday.
"We're right at the threshold of where you would expect to see health effects," said Lachmuth.
"Right now, there are no limits on the number of boats that can whale-watch. If you want to go fishing, you need a permit, but with whale-watching that doesn't exist."
The current guideline restricting Canadian boats to 100 metres from killer whales is adequate, she found. Whales in U.S. waters are protected by a 100-yard boundary by law. Environmentalists in the U.S. are pushing to have that distance doubled.
Boaters who through ignorance or recklessness breach the recommended distance increase the health risk to the whales through their vehicles' exhaust, said Lachmuth, whose study was published in Marine Pollution Bulletin.
As it is, under average conditions, killer whales have to breathe at least five times more carbon monoxide than is found 100 metres from a busy Los Angeles highway.
"That really surprised me — I didn't think it was going to be that high," said Lachmuth.
"It's because when you're out on the water there's an inversion because the ocean is so cold and in the summer the air is a lot warmer — the CO is sticking right at that interface and it's not moving vertically at all."
Lance Barrett-Lennard, a senior marine mammal research scientist at the Vancouver Aquarium and Lachmuth's research supervisor, said: "I remember years ago seeing clusters of fishing boats on the water on a still summer day and that blue haze all around, from their own exhaust."
The challenge of Lachmuth's study was to figure out what quantity of pollutants caused difficulties for whales, he said.
"(Lachmuth) had to do the work of figuring out what these doses would mean for an animal that doesn't have sinuses, that can't filter air, that holds its breath and is substantially larger than humans," Barrett-Lennard said.
Lachmuth found that killer whales are more sensitive to air pollutants than humans and experience toxic effects from as little as 39 per cent of an amount which would be toxic to humans.
"For a one-hour exposure to average-case whale-watching conditions, we calculated the southern resident killer whales receive doses of carbon monoxide that are at the threshold of adverse health effects," the study said.
During peak season, the southern resident killer whales are exposed to whale-watching vessels an average 12 hours a day, Lachmuth noted.
One area of study that needs to be explored is the effect of pollutants on whales as they take breaths and dive deep.
"Killer whales experience pressure differences in the lungs while diving that likely . . . influences pollutant uptake," the study said.
"Since the calculated toxicity of carbon monoxide and nitrogen dioxide do not account for the effects of diving, they may be misleading, and much lower concentrations may actually pose an adverse health threat to killer whales."
Also unclear is how much more vulnerable calves and older whales are to the pollutants.
More study is required to learn the effects of boat pollution on vessel operators, naturalists and on-board tourists, said Lachmuth.
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