Urchin Ranching in Noyo Harbor
An Edible Approach to Restoring Kelp Forests
by Trey Petrey
In 2013, a mysterious disease called “sea star wasting syndrome” was first detected along the Mendocino and Sonoma coasts, and it very quickly decimated the main predator of purple sea urchins, the sunflower sea star. Without the sunflower sea star, urchin populations boomed.
Urchins and kelp have long coexisted in subtidal ecosystems, and when the urchin population is kept in check, kelp forests thrive, providing habitat, food, and shelter for other marine life, including the urchins. When the urchin population grows unchecked, however, the kelp forests disappear. As a result of the increased number of urchins and the warming ocean temperatures, the kelp forests along our coast were reduced by as much as 96% between 2016 and 2020—and they have yet to recover. With no kelp, what is left behind are urchin barrens, where only spiny purple urchins cover the sea floor.
Although they are opportunistic omnivores, eating decaying plant and animal matter and even other urchins, sea urchins generally consume algae to survive, including kelp. Without enough to eat, they use up the reserves in their gonads, the orange colored “uni” that is sought after as a culinary delicacy, making them of little value even as a food source. Interestingly, they have the uncanny ability to change their metabolism, so instead of dying, the emaciated shells continue to roam the reefs in search of drifting algae and eating up new kelp as soon as it begins to grow.
One solution to the over-abundance of purple urchins is to remove the starving creatures from the ocean and fatten them up in a process called “urchin ranching,” transforming them into rich umami-flavored uni.
In November 2023, Noyo Center for Marine Science purchased a 40-foot shipping container outfitted with a land-based urchin aquaculture system. This compact urchin ranch is one of several projects funded by a grant through Congressman Jared Huffman’s Community Projects Funding, administered through National Oceanic and Atmospheric Administration. SeaGrant/Moss Landing Marine Lab built the system and will be one of the center’s partners moving forward.
With this system, purple urchins collected from the barrens are placed in “raceways”—troughs with circulating salt water in a temperature-controlled environment—and fed a seaweed-based nutrition to fatten them up. In approximately 10-12 days, the urchins begin to develop the first lines of roe, and it takes approximately 6-10 weeks to get them up to market size. The center hopes to be able to use water directly from the Noyo River for the system, making needed adjustments to the salinity and temperature. Ranching urchins in this environment also has the benefit of more consistency in the flavor and size, since uni’s flavor stems from its diet; in a wild environment it’s difficult to know what, or how much, the urchin is eating. Fort Bragg urchin diver, Grant Downie, was recently quoted in Sierra magazine, noting that, “With ranching, you would always have good urchin to offer, so you’re not going to lose your markets to other countries’ urchin.”
The Noyo Center first partnered with the Nature Conservancy (TNC) in 2019 through a grant provided to the Norwaybased company, Urchinomics. Its goal was to demonstrate the feasibility of urchin ranching to enhance kelp forest restoration efforts, which are set to continue along the Mendocino Coast until at least 2026. As part of this program, TNC plans to donate urchins harvested in restoration projects to the Noyo Center, partially offsetting costs of kelp restoration and creating an incentive for harvesting purple urchins. Urchins harvested this way will help maximize restoration outcomes and further create a circular restorative opportunity for our community and economy.
Early in their work, TNC identified a need to reduce the costs associated with raising these animals for consumption and to develop a sustainable, effective feed that worked well in an aquaculture environment. As a result, they collaborated with urchin ranchers from San Diego to Oregon, putting together a workshop that brought together a dozen urchin ranchers to share lessons learned in this nascent practice. From this workshop, TNC developed a manual for urchin ranching which can serve as a resource for would-be urchin ranchers. This interactive manual will be publicly available in the spring of 2024. Noyo Center will figure out how to adapt these practices to Noyo Harbor, factoring in the unique challenges we face with rough seas and a seaweed—Nereocystis luetkeana—that grows on an annual cycle.
Based on the work of other urchin ranching researchers, such as the company Urchinomics, and the urchin ranching trials being conducted by Bodega Marine Laboratories, we hope this small pilot project in Noyo Harbor will demonstrate one option which has the potential to have a measurable impact on kelp forest restoration, as well as the potential for the growth of the Blue Economy on our coast. There are also opportunities for educating the community, such as our school student programs, hosting uni tastings, and science workshops introducing the public to the overpopulated shellfish.
The urchin ranching project at the Noyo Center Marine Field Station is the first of several ambitious projects geared towards sustainable aquaculture and ecosystem restoration. Among them is an effort to address the collapse of the red abalone population, involving a unique partnership led by the Kashia Band of Pomo and including U.C. Davis, Bodega Marine Lab, and the Noyo Center for Marine Science. Once a vital $44M recreational fishery industry on the North Coast, abalone populations have plummeted as the surging urchin population outcompetes them for kelp. It is critical that an abalone broodstock program be initiated soon to help their numbers recover. Noyo Center hopes to create what is called an integrated, multitrophic aquaculture system that connects urchin, abalone, and seaweed grown in tumble tanks onshore into a closed recirculating water system.
The installation of a low-tech, land-based urchin ranching system will allow scientists with the Noyo Center to explore the possibility of large-scale production of purple urchin at its future Ocean Science Center on the Fort Bragg Headlands, as well as elsewhere in the region. This preliminary effort could prove essential to restoring kelp forests by transforming starving, commercially worthless urchins removed from urchin barrens into a valued, restorative seafood product—and supporting a new regional aquaculture industry at the same time.
Folks interested in getting a peek inside the urchin ranch—and learning more about the kelp crisis overall—can attend North Coast KelpFest!, running May 18 - June 16 in both Mendocino and Fort Bragg. The month-long festival includes an ongoing art show at the Mendocino Art Center, a documentary screening at the Mendocino Film Festival, a panel discussion among researchers and other experts at the Noyo Center Marine Field Station, art workshops, citizen science events, and much more. There is much to do to help the kelp forests recover, but with a multiplicity of efforts, including urchin ranching, these crucial ocean ecosystems can again thrive off the California coast.
Noyo Center for Marine Science
338 N Main St, Fort Bragg
(707) 733 6696 | NoyoCenter.org
Discovery Center open Thurs - Mon 11am - 5pm
Crow’s Nest Interpretive Center (South Noyo Headlands Trail) open daily 11am - 3pm
Find out more about North Coast KelpFest! at NorthCoastKelpFest.org.
Trey Petrey is a member of the staff of the Noyo Center for Marine Science, managing the interpretive centers and supporting work on the urchin ranching project and other special projects coming up in 2024.
Photo credits: Urchin barren image by Abbey Dias. Urchin ranch image by Richard Millis of Noyo Center for Marine Science. Other images courtesy of Noyo Center for Marine Science.