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Could ‘Urchin Ranching’ Help Restore Northern California’s Undersea Kelp Forests?

The recent die-off of large parts of the bull kelp forests that were so prevalent off the Northern California coast has researchers wondering if harvesting the purple urchins that were one of the causes of that die-off might help restore those underwater forests.

A marine heat wave coupled with an El Nino event from 2014 to 2017 helped the purple urchin population explode. Those urchins scrape the sea floor, making it hard for bull kelp to gain a footing.

A study that recently came out in the journal Scientific Reports documented the bull kelp die-off and purple urchin population surge.

A scientific diver observes purple sea urchin barrens in California. (Cynthia Catton/California Department of Fish and Wildlife)
A scientific diver observes purple sea urchin barrens in California. (Image credit: Cynthia Catton/California Department of Fish and Wildlife)

The loss of the bull kelp forests — over 90 percent off Northern California — caused the $44 million recreational abalone fishery to be closed and the north coast commercial red sea urchin fishery to collapse.

According to lead author Laura Rogers-Bennett, a scientist with the University of California Davis:

“We’re in the 20th year of this monitoring program, and we can confidently say, this is uncharted territory that we’re in. We’ve never seen purple sea urchins at these densities before. This paper really shows what it takes in terms of multiple stressors to crash a bull kelp forest.”

Consequently, Urchinomics, a local shellfish company, is working with researchers to see if purple urchins can be removed from the sea floor and “fattened up” for sale in the sushi market.

For more info, check out this article in Popular Science, which features comments from’s own Francesca Koe!

SourceUC Davis
John Liang
John Liang
John Liang is the News Editor at He first got the diving bug while in High School in Cairo, Egypt, where he earned his PADI Open Water Diver certification in the Red Sea off the Sinai Peninsula. Since then, John has dived in a volcanic lake in Guatemala, among white-tipped sharks off the Pacific Coast of Costa Rica, and other places including a pool in Las Vegas helping to break the world record for the largest underwater press conference.