Environmentalists are planning to petition the feds later this month to list Pacific Northwest orca whales, also known as killer whales, under the Endangered Species Act. They say that PCB pollution is making the orcas more vulnerable to disease and early death and that devastated salmon runs in the region are hurting the orcas, which rely on the fish for as much as 90 percent of their diet. A spokesperson for the National Marine Fisheries Service says the whales’ decline is being taken seriously, but that scientists still aren’t sure what is causing it. Kieran Suckling of the Center for Biological Diversity, the lead author of the orca petition, says that the agency’s response doesn’t surprise him because NMFS has a record of inaction on endangered species, and that he expects the case will end up in court. He says saving the whales “will require nothing short of restoring the entire ecosystem” of the Northwest.

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