Starved and emaciated, sea lion pups are beaching themselves along the Pacific Coast.

A strong El Nino tropical weather pattern is to blame. Unusually warm sea surface temperatures in the western Pacific are moving east, forcing the sea lions’ natural food sources — squid, hake, herring and anchovies — to seek out cooler waters.

Adult sea lions have enough fat stored up to survive the resulting food shortage, but their pups aren’t so well-equipped. Richard Evans, medical director of the Pacific Marine Mammal Center in Laguna Beach, Calif., tells NPR’s Guy Raz that by the time the animals get to his team, they’re in the third stage of starvation.