Local southern-resident killer whales are at the highest risk of death and long-term population impacts in the event of an oil spill in B.C.’s coastal waters, according to a new study of mammals and oil exposure.
Researchers used projections from Trans Mountain pipelines to estimate the dispersion of oil from a tanker incident in Haro Strait, near Victoria, and overlaid that with both the range and behaviours of common marine mammals.
Both northern- and southern-resident killer whales and sea otters are at the most risk, said co-author Misty MacDuffee, but 18 of the 21 mammals considered are at high risk.
“Most of what we know about how killer whales fare after exposure to oil comes from what we learned after the Exxon Valdez oil spill in 1989,” she said.
One third of the local resident population was killed by oil exposure after that spill and is just now starting to recover. About 40 per cent of the transient killer-whale group was killed.
“The transient orcas lost all their breeding females, so that lineage will be gone when the remaining individuals die,” she said.