Sidney – Marine mammals in general are inherently vulnerable to oil spills due to the extended time they spend at the water’s surface, but a new study examined specific traits and population considerations among BC’s marine mammals to determine differences.
The paper, Oil Spills and Marine Mammals in British Columbia, Canada: Development and Application of a Risk-Based Conceptual Framework, was published in the journal Archives of Environmental Contamination and Toxicology by researchers from the Raincoast Conservation Foundation and the Ocean Wise Conservation Association.
It found that of the 21 marine mammals examined, 18 are at high risk, with Northern and Southern Resident killer whales and sea otters considered as being at especially high risk from an oil spill event in BC waters. Both killer whales and sea otters experienced high mortality following Alaska’s 1989 Exxon Valdez oil spill.
The study indicates that of the 21 BC marine mammals examined, only the sperm whale, Northern elephant seal, and California sea lion were found to have a moderate risk of experiencing population level effects from an oil spill. In addition to Resident killer whales and sea otters, Bigg’s (transient) killer whales and Steller sea lions were also found to be at especially high risk.
“First, we examined exposure pathways—ways in which spilled oil can impact an individual animal, such as ingestion, inhalation, direct contact and ingestion via contaminated prey,” explains Raincoast biologist Adrianne Jarvela Rosenberger, the study’s lead author. “We then combined this with the likelihood of impacts to the whole population, using factors like their distribution, habitat use, reproduction, and their ability to switch to other prey. We were then able to rank each species according to its overall risk of suffering detrimental impacts as a result of an oil spill event.”
“Given the approval of Kinder Morgan’s Trans Mountain project, it’s important to note that the populations deemed to be at greatest risk for oil spill exposure and consequence are also those with a high conservation concern as identified by their listing under Canada’s Species at Risk Act,” adds Jarvela Rosenberger.