Sonoma-Mendocino Bull Kelp Recovery Program — Reversing California's Urchin-Barren Collapse

Northern California's bull kelp forests collapsed after 2014, when a marine heatwave and a sea star wasting disease outbreak removed a key urchin predator, allowing purple sea urchins to multiply unchecked and strip reefs bare. The Sonoma-Mendocino Bull Kelp Recovery Program, coordinated by the Greater Farallones Association within the Greater Farallones National Marine Sanctuary, pairs commercial urchin divers, NOAA, the California Ocean Protection Council (OPC) and the California Department of Fish and Wildlife to physically remove urchins and replant kelp at priority coves.
The programme has secured USD 9.5 million in funding to date, including USD 4.9 million from NOAA under the US Bipartisan Infrastructure Law, plus close to USD 500,000 from OPC and CDFW specifically for urchin removal at two Mendocino County sites. Divers have removed nearly 50,000 pounds of purple urchins — one diver alone cleared 7,700 kg from a single cove in one season — reducing densities below two urchins per square metre, the threshold researchers say is needed for kelp to recover, with positive early signs of regrowth reported.
The programme targets restoring roughly 11 hectares of kelp forest across five priority coves in Sonoma County, alongside a recovery effort at Big River in Mendocino County; full canopy recovery has not yet been independently confirmed at scale, so this remains an evidenced but still in-progress restoration rather than a completed success story.

Read the full analysis: https://www.fisheries.noaa.gov/feature-story/pioneering-project-restore-bull-kelp-forests-greater-farallones-national-marine