Kelp forests have declined across the world and governments, organizations and businesses are mounting ambitious efforts to protect and restore 9 million acres of kelp globally by 2040.
Still, the dilemma remains: is kelp restoration even feasible, given the billions of purple urchins feasting on the seaweed and eradicating it from the ocean?
“That is the question that keeps me up at night,” said Tristin McHugh, the Nature Conservancy kelp project director. “But what’s the alternative? Do we let this ecosystem lapse into something that can be irreparable? I’ve seen the success stories from around the world. When a culture acknowledges that an ecosystem is worth saving, they will do it. This might be our chance.”
Restoration methods vary depending on local ocean conditions, scientific expertise, community engagement and the money that’s available, McHugh said. What works in one area may be less successful elsewhere.
The world’s most ambitious and largest kelp restoration effort in South Korea has an annual budget of $29 million and aims to restore about 123,500 acres of kelp forest by 2030. The 20-year project has installed over 49,000 acres of kelp on both artificial and rocky reefs at 173 sites using aquaculture techniques. Kelp activists say it’s proof that with enough funding and nationwide focus, restoration at scale is possible.
In Tasmania, researchers have been transplanting baby kelp grown in the lab from algae that possess a higher tolerance for warmer waters. In Norway, they have found success with tossing green gravel – small rocks seeded with baby kelp – into the ocean from a boat. And in Australia near Sydney’s coastline, scuba divers have transplanted crayweed –- the country’s most important canopy-forming seaweed – onto reefs using mats drilled into the seafloor, cable-ties and silicon tubing, leading to significant regrowth of underwater forests.
Most efforts on the West Coast in the past four years have been much smaller in scale and duration, with a few seeing limited success.
In California’s Mendocino County, nonprofits, government agencies, commercial urchin divers and volunteers hand-harvested tens of thousands of purple urchins in urchins barrens in Noyo Bay, 170 miles north of San Francisco, to sell them to seafood processors. Scientific surveys at the restoration site documented an increase in kelp densities over 15 months, with bull kelp reaching 20% of the historical density while little to no kelp growth happened in the control area.
But the project did not lead to a full regrowth of the canopy. And the restored area dwindled after urchin removal ended.
Elsewhere in California, recreational divers successfully petitioned the state to allow higher urchin harvests in several northern counties and unlimited culling of purple urchins at specific locations. Over two years, divers at Tanker Reef in Monterey County crushed more than half a million urchins, leading to a phenomenal regrowth of giant kelp, the predominant canopy-forming kelp species in the area.
In Oregon, the Kelp Alliance and local recreational divers are working to facilitate similar removal opportunities and to ease state permitting for such efforts. The Oregon Department of Fish and Wildlife said it’s developing a proposal to increase purple urchin harvest limits as well as to form small experimental urchin culling areas similar to California’s to allow the public to participate more broadly in kelp restoration.
But, unlike regulators in California and Washington, Oregon’s fish and wildlife management agency told The Oregonian/OregonLive it is not pursuing a statewide kelp forest conservation and restoration plan – leaving the job to the Oregon Kelp Alliance and its supporters.
— Gosia Wozniacka covers environmental justice, climate change, the clean energy transition and other environmental issues. Reach her at [email protected] or 971-421-3154.
