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OCH BLOG

Kelp Aquaculture in Orange County

Seaweed could be the next super food the world needs to cultivate. All species of seaweeds are not plants – they are types of algae called macroalgae. In fact, the only similarity between seaweed and land plants is the usage of photosynthesis to convert sunlight into energy. There have been about 12,000 species of seaweed described to date. At a glance,

Kelp forest. Photo by Nancy Caruso.

seaweed is globally responsible for providing an abundance of food, producing about 70% of the world’s oxygen, and capturing extensive amounts of the world’s carbon emissions. Amongst all the various species of seaweed, the beneficial uses seem almost endless. To name a few, uses of seaweed range from human consumption, medicine, skin care, and plant fertilizer or animal feed to biodegradable plastic substitutes, carbon sequesters, and even possible biofuels. The practice of cultivating and harvesting seaweed has been dated back 12,000 years ago and still continues to gain additional traction as various forms of seaweed aquaculture have become popularized around the world. Seaweed aquaculture is still in the beginning stages in the United States as the industry looks to prove it’s worth past the possible impacts and consequences. The main concerns of seaweed aquaculture in the United States are stringent regulations, benthic productivity impacts, the feasibility of operating offshore, and the stigma of eating and working with seaweed. When we dive deeper into the beneficial uses of seaweed, one could see that all the numerous pros of seaweed aquaculture greatly outweigh the cons. Through seaweed aquaculture, the problems of climate change, environmental sustainability, and food shortages are all addressed in a beneficial way.

Kelp Aquaculture. Photo credits: FoodFarmNews

Common varieties of harvested seaweed species in the United States are dulse, kombu, and bladderwrack. However, most farmed seaweed is usually some form of kelp. Kelp farming is done using a mooring that hangs thick ropes with strings of kelp seedlings perpendicularly attached below the surface of the water. The crops require almost no maintenance during the normal six-month time frame that the kelp takes to mature. The various species of kelp are incredibly fast-growing and can grow up to two feet per day under ideal conditions.


In fact, the kelp produced provide ecological and environmental benefits of sustainability, excess carbon absorption, battling ocean acidification, filtration, as well as providing important habitat for many marine species in California. The produced kelp is harvested in a sustainable way. By cutting at the base of the blades rather than the stipe or air bladders, the kelp will be able to regrow the blades back relatively quickly. Farming this way greatly reduces the amount of waste from one harvest to the next as well as allows the farmed, regenerating kelp forest to continuously be used as habitat, shelter, or nursery by the various species of marine animals in the ecosystem. Contrary to most agriculture and aquaculture, kelp aquaculture specifically has nearly a non-existent “foodprint”. It doesn’t require any extra irrigation, feed, nor fertilizer. Additionally, the farmed seaweed can be used in livestock farming for animal feed. Animals feeding on the seaweed products have been proven to have lower emissions of carbon dioxide. Kelp aquaculture can also be modified to a regenerative ocean farming system to grow kelp alongside oysters, mussels, and clams to create a diversified, healthy ecosystem whilst developing a sustainable yield.

Regenerative Aquaculture. Credit: GreenWave.

The environmental and agricultural potential that seaweed has makes the algae farming industry extremely valuable. The worldwide market for seaweed cultivation is estimated to be worth $16.7 billion in 2020 with projections of nearly doubling within the next 5 years. Over the last few years, seaweed aquaculture has continuously expanded from the temperate coastlines of China, Japan, and Korea to along the coast of California. Although California is still a small player in the overall market, farms like the Catalina Sea Ranch, Hog Island Oyster Farm, and Salt Point Seaweed have garnered a lot of public and governmental interest. The U.S. Department of Energy granted Catalina Sea Ranch over $450,000 to kick off the first U.S. aquaculture farm permitted in federal waters around 6 miles from the coast of Huntington Beach. Catalina Sea Ranch has used their awarded money to fund additional research to enhance their aquaculture’s synergy and husbandry of kelp and other offshore aquaculture to create a new sustainable industry within California.


Unfortunately, the kelp aquaculture industry in California is still in its infancy stage. The hurdles to establish and maintain seaweed aquaculture haven’t yet been addressed. Catalina Sea Ranch fell short on their end due to bearing the weight of the industry’s growing pains, newfound regulatory agency demands, as well as a $10-million accidental wrongful-death lawsuit. Sadly, they failed to meet regulatory compliance with the California Coastal Commission and the U.S. Army Corps of Engineers permit requirements and even ignored enforcement letters. Catalina Sea Ranch painted themselves an erroneous picture of seaweed aquaculture conveying shortcuts and misuse of equipment – like using old tractor batteries to weigh down lines – rather than proper and well-maintained equipment per regulations. Despite all of this, Catalina Sea Ranch still provided a blueprint to what could be a booming, environmentally friendly industry in the future.

Edible seaweed foraging. Photo credits: Michael Macor

As technology continues to progress, the feasibility of seaweed aquaculture will become more and more realistic on a large scale. Luckily, the idea of future seaweed aquaculture is still being pursued by California regulatory agencies and eventually may be able to supply California and the United States’ demand for seaweed instead of importing more than 90% of the seaweed consumed in the United States. If you’re a California resident and love seaweed, make sure to check out the California Department of Fish and Wildlife rules and regulations for recreational seaweed harvesting. Popular edible seaweed species of Wakame, kombu, and bladderwrack are found throughout California’s coast; however, no harvesting is allowed in State marine reserves or protected areas. You can also help promote the seaweed aquaculture industry by buying local seaweed products from coastal restaurants and stores that provide them. Lastly, spreading the word of all of seaweed’s beneficial uses both for consumption and the environment may greatly influence the general acceptability and demand for more seaweed aquaculture along California’s coast.

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