urchins on kelp
Photo: Dan Schwartz

What happened to the kelp?

Since 2014, kelp forests along the West Coast have declined due to a combination of extreme warm water events (marine heatwaves and El Niño), the loss of predatory species like the sea otter and sunflower sea star, and dramatic increases in native purple sea urchin populations. The combination of these stressors was too much for kelp forests to persist, and many have transitioned into “urchin barrens”. Some areas, such as those in Northern California, have kelp forests that have declined by over 90%. Reef Check’s long term monitoring program has found that while this decline was less in other areas, urchin densities have steadily increased in other regions as well. To learn more about kelp forest and urchin barren dynamics, click here.

What are we doing to address this?

Reef Check is testing if a reduction in herbivores (urchins) will facilitate kelp re-growth. At several locations in central and northern California, we will explore different methods to reduce purple urchin populations and promote kelp growth. These sites were chosen as restoration sites because they show potential for kelp recovery and because they are of particular interest to the local communities.

Ongoing monitoring and support are essential to the success of these projects!

Big Sur Reef Restoration

In 2022, Reef Check started a restoration site in Big Sur by partnering with commercial urchin divers to reduce urchin densities within a barren area approximately 2.5 acres in size. What is unique about this site is that it is surrounded by relatively healthy kelp forests on all sides. We believe that this will assist with a faster recovery of the kelp forest. In October 2022, approximately 6,000 lbs of urchins were removed from the site. In 2023, low urchin densities were maintained and kelp grew back. In 2024, Reef Check received a Scientific Collecting Permit (SCP) to cull urchins at the site and will continue work at this site with Reef Check volunteers. The lessons learned from this project will improve our understanding of how early intervention may be crucial to kelp restoration on the West Coast.

Aerial photos showing the area of the barren and nearby kelp forests were taken in June 2022 (left) and November 2023 (right). The red oval shows the location of the barren (the boat in the left picture is anchored in the barren where surveys and urchin removals took place).

Mendocino County Restoration Projects

purple urchins in nets

Beginning in 2020, Reef Check launched a collaborative approach to restore the bull kelp forest ecosystems in Mendocino County at two sites with funding from the Ocean Protection Council. This collaboration engaged with commercial sea urchin divers, Reef Check volunteers, community volunteers, government agencies, and other nonprofit organizations. The project has been instrumental in informing the development of a restoration ‘toolkit’ as well as providing economic benefits to communities hit hardest by the loss of the kelp forest. Kelp restoration via commercial hand harvest of purple urchins occurred at two sites, Noyo Bay, beginning in August 2020, and Albion Cove in July 2021. Results from 15 months of restoration efforts at Noyo Bay and four months at Albion Cove are now available here: Full Results Report and Summary Results Report.

Ongoing restoration at Albion Cove is being conducted in collaboration with The Nature Conservancy, Moss Landing Marine Lab, Sonoma State University and the California Department of Fish and Wildlife.

Tankers Reef Kelp Forest Restoration Project

urchins on holdfast
Photo: Kate Vylet

In December 2020, the California Fish and Game Commission (FGC) adopted an amendment that allows divers with a California sport fishing license to take unlimited amounts of purple sea urchins and red sea urchins at Tankers Reef in Monterey County and cull them underwater. The goal of this amendment is to allow recreational divers to remove urchins in order to restore kelp forests at this site. Reef Check is working with the California Department of Fish and Wildlife (CDFW), Monterey Bay National Marine Sanctuary (MBNMS), and Giant Giant Kelp Restoration (G2KR) to monitor this kelp restoration effort to address key management questions that will be instrumental to the advancement of restoration in California.

Latest monitoring results: September 2023

Caspar Reef Restoration

Along with Tankers Reef, the California Fish and Game Commission (FGC) also allowed unlimited take of purple sea urchin and red sea urchin at Caspar Reef in Mendocino County. Since 2020, recreational efforts to cull urchins have been led by the Waterman’s Alliance. In 2024, Reef Check staff and volunteers plan to conduct additional monitoring and assist the efforts led by the Waterman’s Alliance.

Oregon Restoration Projects

Reef Check Oregon began to work collaboratively with the Oregon Kelp Alliance (ORKA) to monitor and assess effectiveness of restoration efforts across five sites along the Oregan coastline. More information on ORKA program and their restoration efforts can be found here.

divers removing urchins
Photo: Patrick Webster