LA Times: Marine mammals are dying in record numbers along the California coast

Published by The Los Angeles Times: October 3, 2025

On a spit of sand 12 miles north of Santa Cruz, a small, emaciated sea lion lay on its side. The only sign of life was the deep press of its flippers against its belly, relaxing for a few seconds, then squeezing again.

“That’s a classic sign of leptospirosis,” said Giancarlo Rulli, a volunteer and spokesperson with The Marine Mammal Center, pointing to the young animal’s wretched self-embrace. The corkscrew-shaped bacteria, leptospirosis, causes severe abdominal pain in sea lions by damaging their kidneys and inflaming their gastrointestinal tracts. “They hold their stomach just like that. Like a sick child with a bellyache,” he said. 

Since the end of June, officials say nearly 400 animals have been reported stranded or sickened along the Central Coast beaches. More than two-thirds of them have died, Rulli said. Hundreds more probably were washed away before anyone spotted them, or died at sea. 

“It’s been a brutal year. ... It’s been hard on the animals. It’s been traumatic for the volunteers. It’s a lot.”

The historically large and long bacterial outbreak is adding to an already devastating death toll for the seals, sea lions, dolphins, otters and whales who live in and migrate through the state’s coastal waters.

There are the poisonous algal blooms off the central and southern coasts. There are massive changes in food availability and distribution across the Pacific. And there are growing casualties from ship strikes, record numbers of entanglements in rope and line, and a new heat blob forming in the eastern Pacific. This year may be remembered as one of the gravest for marine mammals on record. Or, more worryingly, a sign that our ocean environment is changing so drastically that in some places and seasons, it’s becoming uninhabitable for the life it holds.

The network of volunteers who tend to stranded marine life is running ragged, said Rulli, answering dozens of rescue calls a day. “It’s been a brutal year. ... It’s been hard on the animals. It’s been traumatic for the volunteers. It’s a lot.” 

Whether all of these pressures and changes are related, or are completely separate phenomena happening at the same time in the same place, scientists don’t know. 

“We’re trying to build our understanding of how ocean conditions relate to the occurrence of disease. But it’s a work in progress. And the world is changing quickly underneath our feet,” said Jamie Lloyd-Smith, an ecologist and evolutionary biologist at UCLA.

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