Scientists are hunting urchins to save California's crucial underwater forests

Scientists are in a race right now to save underwater kelp forests along much of the California coastline that are being devoured by a species of sea urchin. Researchers say the bull kelp forests play an important role in the region's underwater ecosystem and the survival of area fish and wildlife.

"What you used to look out on this coast and see was just an incredibly dense, beautiful kelp forest that hosted up to a thousand different species," said Norah Eddy of The Nature Conservancy.

The Nature Conservancy and several other groups have been leading a pilot project off Casper Beach in Mendocino County to try to restore the bull kelp forests. To do that, the researchers have assembled a team, partly made up of volunteers, to help cull the kelp's main predator, the purple sea urchin.

"My friends were shocked when they found out that I was going out to kill animals on purpose," said Joy Hollenback, a veterinarian from Berkeley, who has been volunteering for the project. "Taking the urchin means the other animals get to thrive."

The population of purple sea urchins grew rapidly in 2013 after its main predator, the sunflower starfish, began to die off. Scientists say warming ocean waters are to blame, making the starfish susceptible to a deadly disease.


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"The starfish, I mean all of the starfish, got a wasting disease, and it just caused them to dissolve," said Hollenback.

With 90 percent of the sunflower starfish population dead, a sizable part of California's underwater ecosystem has been impacted.

Since the pilot project began in 2019, researchers say they've made progress at Casper Beach, reducing the urchin population there by 80 percent. Recently, Bull Kelp and Sunflower Starfish have begun to return to the area.

"When we started there was nothing but rocks and urchins," said Jared Russo of the Watermen’s Alliance. "Now it’s beautiful. It’s almost like it used to be." 

The research is still ongoing, but scientists say they hope to eventually apply lessons learned from Casper Beach to other coastal areas where kelp forests are now under threat.