North Coast kelp collapse: Yurok Tribe confronts a changing ocean

Northern California's kelp forests have been in steep decline, with an estimated 95% loss of canopy since 2014. NASA and USGS Landsat analysis shows Northern California's kelp canopies' rapid decline was driven by a marine heatwave, El Niño conditions, and the loss of sunflower sea stars to wasting disease. With the region's primary urchin predator gone, purple urchins surged across the seafloor and converted once‑productive kelp forests into persistent urchin barrens.

The disappearance of sunflower sea stars caused the ecosystem's resilience to plummet, leaving little capacity for kelp to recover under current ocean conditions. Along the Klamath River shoreline, the Yurok Tribe's marine program is documenting the same pattern NASA identified offshore. Unlike the towering bull kelp farther south, benthic kelp, which grows as a thin, fuzzy layer on rocks, has also been threatened.

"The benthic kelp is in threat of decline because the system's out of balance with no top‑level predators anymore," said McKernan. "Sea otters and sunflower sea stars kept purple urchins in check, and without them, urchins have wiped out large kelp forests."

The Yurok Tribe relies on several species of kelp for food, cultural materials, and regalia. Benthic kelp supports abalone, a culturally important species used for both subsistence and ceremonial dress. The loss of kelp also affects rockfish, crabs, and other nearshore species that depend on kelp for shelter and feeding.

"The tribe uses kelp directly…there are several different species of kelp that are harvested and used directly as food. Also, that kelp feeds an ecosystem that's important to other culturally important species, both for food and for regalia, those primarily being abalone," said McKernan. "Abalone depend on benthic kelp for food, and abalone is an important food source, as well as cultural material for regalia. In tribal regalia, both jewelry, as well as dresses, and other parts of their cultural ceremonies, and then everything else that the kelp supports is also impacted."

Kelp loss varies along the North Coast, with larger kelp beds historically found near Trinidad and Crescent City. Recent monitoring has documented that benthic kelp has been grazed down north of the Klamath River, raising concerns for tribal harvesters and marine programs working to track changes along the coastline.

"Down in the Sonoma-Mendocino coast, the tribes down there, the Pomo and others, have uses of bull kelp, as well as Tolowa up in Del Norte County, as well as Yurok, but kind of more localized around, the Klamath River, and any tide pools between, Trinidad and Crescent City, a lot of those areas, the rocky kelp, is the more commonly used," said Kevin McKernan with the Yurok Tribe.

Scientists say community awareness of benthic kelp loss remains low despite the scale of the ecological shift. The absence of sea otters for more than a century and the recent collapse of sunflower sea stars have allowed purple urchin populations to explode, creating "urchin barrens" where kelp once thrived.

"I think there needs to be a greater awareness by the community about the system being out of balance, meaning the lack of predators," said McKernan. "A lot of people don't think much of sea stars or starfish, but they're critical predators. Hopefully (they) make their way back here, you know, in the next several years."

Reintroduction of sea otters is being explored as a long‑term restoration strategy. Tribal scientists say otters could help restore ecological function in the nearshore environment, similar to recovery seen along the Central Coast.

"One main predator that we've been missing for the last 100-plus years is the sea otter on the North Coast of California. There are perceptions and realities, and you know all the things that usually go around the introduction of new species that the community may or may not embrace," said McKernan. "Anywhere where sea otters currently exist or have come back (and) have shown to help increase kelp bed populations, primarily down in the Santa Cruz and Monterey area, we'd expect the same up in this area."

Residents can also help by reporting urchin barrens or participating in urchin harvesting efforts. Purple urchin outbreaks along the North Coast often go unnoticed, but tribal scientists say public awareness is critical as benthic kelp continues to decline. When residents see urchin barrens while tide‑pooling, they're encouraged to report them to Cal Poly Humboldt's marine lab in Trinidad or to the Yurok Tribe's marine program, which monitors the largely unobserved coastline between Trinidad and Crescent City. Both groups are working to reduce urchin numbers and restore kelp, and say harvesting urchins can help relieve pressure on the ecosystem.

"Not a whole lot of people scuba dive up here because of our rough conditions. Anytime you see an overabundance or infestation of purple urchins, report it. If you're in Trinidad, report it to Cal Poly Humboldt Marine Lab down there. They're actively trying to control urchins and restore kelp down around the Trinidad area," said McKernan. "North of Trinidad, there's not a whole lot of folks paying attention to or looking at the coastline from Trinidad all the way to Crescent City, but that's what we're doing. The tribe's marine program, so they're always welcome to report urchin barons and then help by getting out and harvesting them. If people harvest them, there are creative ways to use them, because every urchin removed helps relieve pressure on the kelp."

Maranda Vargas can be reached at 707-441-0504

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