An audacious effort to restore a critically endangered species to the California coast has moved one step closer to fruition after scientists temporarily released more than a dozen lab-reared sunflower stars into Monterey Bay. 

Once a common sight for divers, these manhole-sized, many-armed sea stars have not been seen south of the Bay Area since 2018, after a mysterious illness killed around 6 billion individuals along the West Coast of North America. 

Set free, the lab-reared animals quickly devoured their preferred prey, sea urchins, which have ballooned out of control in the years since the outbreak. The stars’ successful hunting raises hopes that the animals could one day be set free for good, helping to restore urchin barrens into lush, productive kelp forests. 

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A sunflower star feeds on urchins during the Sunflower Star Laboratory’s outplanting fieldwork in Monterey Bay, Calif., on June 19, 2026.

“This work is the foundation for the upcoming future permanent outplanting in our state,” said Reuven Bank, the executive director of the Sunflower Star Laboratory, which oversaw the research. “What we’ve found really supports the strong restoration potential of sunflower stars and that future outplanting can have a significant positive effect on the environment.”

An urchin barren covers the shale reef in the Sunflower Star Laboratory’s outplanting site in Monterey Bay, Calif., on June 19, 2026.

Between 2013 and 2017, a fast-moving, highly fatal disease known as sea star wasting disease swept up the West Coast, causing widespread death among more than 20 sea star species. Sunflower stars, known scientifically as Pycnopodia helianthoides, were hit particularly hard, declining by roughly 92% across their historical range from Baja California, Mexico, to the Aleutian Islands off Alaska. Today, the species is rarely found south of Puget Sound.

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It took years for scientists to untangle the mystery underlying wasting syndrome, and many questions remain to this day, but in 2025, researchers identified the bacterium Vibrio pectenicida as the likely cause.What triggered the outbreak in 2013 remains unknown, yet subsequent research has shown that the bacterium tends to thrive in warmer waters, and there were several notable heat events around that time, including a massive, unprecedented marine heat wave in the Pacific Ocean known as “the Blob.”

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