Marine Biologists Finally Know What's Killing the Sea Lions Off Washington — And It Isn't Ships

A dead sea lion washes up south of Westport with a clean straight cut across its back, and everyone who sees it blames a boat. A closer look shows the cut happened after the animal was already dead — and that the real killer left no mark at all. Researchers working along the Washington coast have traced what’s actually filling these beaches, and it’s something the water itself is handing to the animals. Here’s what the evidence shows, why it took so long to spot, and why the usual suspect doesn’t hold up.