Bull kelp hags from the tail of a Southern Resident killer whale.
Photo by Wild Orca.

In the midst of a climate crisis and sixth mass extinction, our continued reliance on fossil fuels not only puts the Southern Resident killer whales at future risk, but maintains a present danger, as oil is transported right through the Salish Sea—one of the most important foraging areas in their west coast range.

The chemicals that naturally occur in crude and refined oil—known as polycyclic aromatic hydrocarbons, or PAHs, make the CDC’s top 10 list of hazardous substances. According to the University of Washington (UW), “Marine mammals’ exposure following a spill can initially occur through inhalation, contact and ingestion as volatile components of the oil slick evaporate.” The danger continues as oil sinks into the water column and eventually persists in seafloor sediment.

After the Exxon Valdez ran aground in Alaska in 1989, two pods of killer whales were witnessed swimming through the spill in Prince William Sound. A 2008 research study found that the fish-eating whales declined by a third, with a yet larger impact on the mammal-eaters; both pods are yet to recover. Research shows that marine mammals exposed to oil have reduced reproductive success, immune system impairment, and disease; all culminating in population decline, with effects that can last for decades.

As the chemical signatures from hydrocarbons (PAHs) can be detected in whale feces, it is possible to test samples pre- and post-spill to understand the level of contamination. Sadly, such information was not available for pre-spill for Alaska’s killer whale populations, and so hindered post-spill monitoring studies.

Consequently Dr. Giles and the team at University of Washington collected samples to test the Southern Resident killer whales’ exposure to PAH. Their analysis showed that although PAH was detectable in their feces, it was at a level regarded as “negligible exposure”—indicating they had not been exposed to a recent spill event. They were able to make this determination as PAHs are more easily eliminated after exposure, unlike PCBs that accumulate over time in blubber.

These samples now act as pre-spill baseline data, and so will assist federal and state agencies in assessing real-time impacts to the whales in the event of a spill. These legacy samples, according to UW, “will provide vital information on recent exposure, indicating the extent of the spill and the effectiveness of the cleanup efforts.”

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Wild Orca’s health monitoring program aims to also test samples we collect for PAHs in the future, to keep this baseline up-to-date.

NOAA Fisheries’ oil spill response plan aims to create a “wall of sound” to deter them away from oil slick areas, with “helicopter hazing, banging pipes and underwater firecrackers on the short list of options” should a spill occur.

Spill. Such a small word for such a catastrophic event, capable of decimating the entire population of Southern Resident killer whales.

De-carbonizing is the best way we can prevent exposing wildlife to such deadly harm. Let your lawmakers know that you support an urgent transition to oil-free alternatives for a healthy future for the Southern Residents, and for us all.