Orca population decline in Pacific Northwest linked to inbreeding.

Inbreeding caused by isolation is contributing to the decline of the Southern Resident killer whales, a small population of orcas living in the Pacific Ocean off the northwest coast of North America, according to a new study. The orca group studied had lower levels of genetic diversity and higher levels of inbreeding when compared with other North Pacific populations. Inbreeding is definitively a problem for this population, with several of the whales being the result of inbreeding between a parent and one of its children. However, human impacts such as boat traffic and pollution have also taken a toll on the animals.