Gray K 1, Barbery K 1, Eddy N 2, Fleener G 3, Polizzi T 3,4, Hamilton A 1, Goudey C 5, Cuevas-Uribe R 6, Ortiz K 6
1GreenWave, New Haven, CT, USA
2The Nature Conservancy, Arlington, VA, USA
3Hog Island Oyster Company, Marshall, CA, USA
4Sunken Seaweed, Eureka, CA, USA
5CA Goudey & Associates, Newburyport, MA, USA Sunken Seaweed, Eureka, CA, USA
6Cal Poly Humboldt, Arcata, CA, USA
In many regions around the world, kelp forests are facing unprecedented declines. 96% of bull kelp (Nereocystis luetkeana) forests in northern California, USA, have disappeared in less than a decade––devastating both ecosystems and livelihoods. Restoration of depleted kelp forests may require multiple interventions, and resource managers need more tools in the restoration toolbox. Urchin removal, artificial reefs, and transplantation of wild kelp from healthy beds to restoration areas have been deployed in California with varying degrees of success. Kelp farming is another strategy that offers the potential to support statewide kelp restoration efforts, but cultivation practices for bull kelp are underdeveloped. GreenWave, together with The Nature Conservancy and Hog Island Oyster Company, tested bull kelp cultivation strategies in Humboldt Bay, California, to optimize farm designs and evaluate the potential of cultivation to support restoration of depleted bull kelp beds along California’s North Coast. GreenWave’s farm site is the first in the state of California to be commercially licensed to cultivate bull kelp. Approximately 480 meters of seedstring, produced using traditional meiospore methods, was outplanted onto a combination of 5-line and single-line arrays at the pilot site in October 2021 and March 2022. Yields during the first harvest ranged from 17 to 35 kg per meter on the 5-line and single-line arrays, respectively, with abundant sorus production. Preliminary results indicate that the array designs and site characteristics in Humboldt Bay are conducive to bull kelp cultivation, with an opportunity for multiple outplantings and harvests per year that will support restoration efforts.