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Nearly 1 million sea urchins raised and dispersed in Kāneʻohe to combat invasive seaweed

Dave Cohen of the DLNR Division of Aquatic Resources at the Sand Island sea urchin hatchery.
Catherine Cruz
Dave Cohen of the DLNR Division of Aquatic Resources at the Sand Island sea urchin hatchery.

One million sea urchins. That’s the milestone the state’s sea urchin hatchery on Sand Island is preparing to hit this year.

The spiny creatures are grown by the Department of Land and Natural Resources to eat invasive seaweed growing on coral reefs in Kāneʻohe Bay on Oʻahu. Staffers collect several thousand collector urchins periodically to disperse out in the bay.

David Cohen has managed the sea urchin hatchery for over a decade. His ʻohana years ago affectionately dubbed him “the mayor of urchin city.”

Cohen says he always knew they’d reach this milestone — he just didn’t think it would take this long.

"We just sort of took things one bottleneck at a time, one step at a time. And I was very enthusiastic and I had great hopes. We just met each bottleneck and sometimes they took a little bit longer than we thought they would," Cohen said.

"Yesterday we had outplanted the 900,000th sea urchin and we're on track to outplant number 1 million in early November. We're very excited about that. It's really fun," he told HPR.

Cohen says overall the reef in Kāneʻohe Bay looks pretty good, although his team does carry out spot treatments in areas where the invasive seaweed appears to be returning.

Cohen was also named employee of the year by the University of Hawaiʻi Research Corporation in 2020.

This interview aired on The Conversation on Aug. 11, 2022. The Conversation airs weekdays at 11 a.m. on HPR-1.

Catherine Cruz is the host of The Conversation. Originally from Guam, she spent more than 30 years at KITV, covering beats from government to education. Contact her at ccruz@hawaiipublicradio.org.
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