In "A Mystery in Alaska" Moore leads viewers through the thicket of often conflicting explanations for why Alaska's Steller's sea lion population has fallen on hard times.

Thomas says his team's work, which included surveying fish populations using sonar, has helped highlight the important role that herring play as a food source for sea lions.

NATURE spoke with Trites about the complexities of Alaska's offshore ecosystems. A number of complex factors are likely to blame for the decline in Alaska's Steller's sea lions, he says.

Frustrated fishermen captured video of killer whales thrashing at sea lions in a harbor. Are fisheries being wrongly blamed?

In the 1970s, the pollock industry in Alaska expanded to become the largest fishery in the world, just as sea lions began to disappear -- a smoking gun?

Steller's sea lions are rapidly disappearing from Alaska's waters, and no one knows why. A broad combination of factors could be responsible.

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