Prevalence of endangered orca inbreeding ‘surprising’, new study suggests

A new study suggests inbreeding is more common than previously thought within the endangered orca population that frequents B.C. waters.

Released Monday, the study found that the amount of orcas that are inbreeding was higher in the population of Southern Resident Killer Whales that numbers only 73 as of last count, according to report co-author Dr. Kim Parsons of the NOAA’s Northwest Fisheries Science Centre in Seattle.

“I think that the magnitude of the level of inbreeding was a little bit surprising, but we knew from the work we had already done and published in 2018 that there was evidence of inbreeding in the Southern Resident Killer Whales and there’s not a lot of mating outside of the southern resident population,” stated Parsons.

Conservational organizations note that this information highlights the need for change fast.

Christianne Wilhelmson from the Georgia Strait Alliance said this study is an opportunity to fuel the conversation to act now to save the endangered orcas.

“I think what the scientists have been reporting on highlights just how urgent more action is need to protect the species, because obviously inbreeding is something we want to see less of and the only way you can have that is to have more individuals of the population,” said Wilhelmson.

Wilhelmson adds that the way to increase the population and reduce inbreeding is better regulate Chinook salmon fishing, reduce pollution in their environment and reduce noise and disturbance.

Scientists behind the study note that there may not be a way to reverse the inbreeding and emphasize that protecting killer whales should still be a top priority to ensure the health of the pods.

The report also suggested that as female killer whales take about 20 years to reach peak fertility, the southern resident females may not be living long enough to ensure the growth of their population.

In its latest census released in November 2022, the Center for Whale Research reported a decline in the number of Southern Resident Killer Whales belonging to J, K and L pods, saying they went down to 73 from 74 a year earlier accounting for two new births and three new deaths.

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