A newly-published study reveals the impact of vessel exhaust emissions on B.C.’s killer whales.  The study, conducted by former UBC department of Zoology graduate student Cara Lachmuth and supervised by Vancouver Aquarium research scientist Dr. Lance Barrett-Lennard, and published in Marine Pollution Bulletin, provides valuable insights on one of the threats faced by this iconic species.

“While training at UBC’s outdoor pool one summer, I noticed that smoke from a nearby BBQ settled over the surface of the water and made breathing very unpleasant—even more so than cycling in heavy traffic,” said Lachmuth. “The experience made me wonder if the situation was similar for whales followed by boats, which generally produce more emissions than cars. No research had been conducted on the impact of air pollution on marine mammals so I began investigating the topic myself.”

Over the span of two and a half years, Lachmuth collected data on vessel traffic, vessel behaviour and atmospheric conditions near the endangered southern resident killer whale population, which currently has 87 members.  She then used a pollution dispersion model to predict killer whale exposure to boat exhaust, and used the results to determine potential health effects. Lachmuth made the following discoveries:

•    When boats operate in proximity to whales, their exhaust emissions have the potential to cause adverse health effects.

•    Exposure to exhaust gases is one threat to the southern resident killer whale population that can be easily managed.

•    To protect whales from emissions, vessel operators should position their vessels downwind of whales and have their engines turned off when   safe to do so.

•    Limiting the number of vessels that idle within 800 meters of whales to an average of 20 vessels at a time keeps emission exposure below the World Health Organization air quality guidelines.

•    Limiting the amount of time that vessels remain with whales is also recommended.

Southern resident killer whales in British Columbia and Washington are exposed to heavy vessel traffic. “What made this study particularly important is that whales don’t have sinuses to filter air the way terrestrial mammals do and they have no sense of smell to help them detect—and hence possibly avoid—engine exhaust,” explained Barrett-Lennard. “They also spend much of their  time diving, which increases pressure in their lungs and causes air pollutants to enter their blood—and reach their vital organs—more rapidly than for non-diving animals.”

Lachmuth’s study is published in Marine Pollution Bulletin and is available here.

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