Maui News

“Conserving Hawai‘i’s Reefs Through Sea Urchin Aquaculture” Free Presentation, May 12

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Want to learn how sea urchin aquaculture is helping to conserve Hawaiʻi’s coral reefs? The public is invited to a free presentation titled “Aquaculture of Native Sea Urchins to Control Invasive Macroalgae” on Wednesday, May 12 at 5:30 p.m. via Zoom.

As natural “algae-munchers,” Hawaiian collector sea urchins can help protect local coral reefs. Learn how Hawaiʻi’s Department of Land and Natural Resources Division of Aquatic Resources is raising and utilizing sea urchins to control invasive microalgae, at a free Zoom presentation on Wednesday, May 12 at 5:30 p.m. The presenter will be David L. Cohen, DAR’s sea urchin hatchery manager.
Photo courtesy Hawaiʻi DLNR.
David L. Cohen.

David L. Cohen of the State of Hawaiʻi Department of Land and Natural Resources Division of Aquatic Resources will be the guest speaker for this “Know Your Ocean Speaker Series” event which is hosted every month by Maui Nui Marine Resource Council.

To reserve a spot at the free presentation, visit the following link: 

Cohen manages the sea urchin hatchery on Oʻahu for DAR and the Research Corporation of the University of Hawaiʻi’s Pacific Cooperative Studies Unit. He holds a Bachelor of Science in General Biology from Connecticut State University.


From 1985 to 1992, Cohen worked in shellfish aquaculture and as a commercial oysterman in New England. Since moving to Hawaiʻi, he has grown food fish and shrimp and worked with captive bred ornamental fish.

In 2010 he started work with PCSU and DAR developing hatchery methods to grow native sea urchins to control non-native invasive macroalgae. The hatchery continues to produce urchins in support of coral restoration, and Cohen said he continues to learn about the ways in which “aquaculture can produce food, enrich our lives, and help restoremthe environment.”

An overgrowth of seaweed can block sunlight that corals need to live, making it difficult for the reef and other marine life to survive, which is why projects like these are essential.


The Hawaiian collector sea urchins, which are raised in DAR’s hatchery, are known for being natural “algae-munchers.” Raising urchins is a long process— It takes about four months for tiny larvae to grow to the size needed before being transferred to Kāneʻohe Bay.

The first step is for divers to remove mass amounts of invasive algae with an underwater vacuum that sucks the seaweed up onto a barge, and then to place juvenile sea urchins on the corals so they can eat the algae in areas that the vacuum couldn’t reach.

DAR, NOAA Fisheries, and the US Fish and Wildlife Service have been working together to clean up the reef in areas at Kāneʻohe Bay since 2011.


To learn more about the aquaculture process of urchin nurseries, tune in to Maui Nui Marine Resource Council’s “Know Your Ocean Speaker Series” on May 12 via Zoom. These monthly virtual events are supported by the County of Maui Mayor’s Office of Economic Development.


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