Sugar Kelp

Saccharina latissima

Also Known As

  • Sea belt
  • Devil's apron

U.S. farmed sugar kelp is a smart seafood choice because it is grown and harvested under U.S. state and federal regulations.

Environmental Impact

Sugar kelp provides net environmental benefits by removing excess nutrients and carbon dioxide and releasing oxygen to mitigate against ocean acidification.


Growing sugar kelp requires no feed — sugar kelp produce their own food through photosynthesis, using sunlight, carbon dioxide and water.

Farming Methods

Sugar kelp lines are seeded in a land based nursery and then placed in tanks or marine waters for grow out.

Human Health

Sugar kelp is high in fiber, vitamin C, vitamin K, iron, calcium, iodine, and magnesium.

  • Availability

    Fresh product when harvested is available February-May, while dried kelp is available year round. 

  • Source

    Commercially farmed in cold water regions along the East and West Coast of the US and Alaska.

  • Taste

    Sugar kelp has a savory and slightly sweet flavor. When dried, a white sweet-tasting powder forms on the blade.

  • Texture

    Crunchy texture.

  • Health Benefits

    High in fiber, anti-oxidants, vitamins, and minerals.

U.S. Farming


  • Permitting for sugar kelp aquaculture is governed by federal, state and local governments.
  • The federal agencies involved are NOAA, the U.S. Army Corps of Engineers, U.S. Fish & Wildlife Service, U.S. Department of Agriculture, the Environmental Protection Agency, the Food and Drug Administration, and the U.S. Coast Guard.
  • Sugar kelp farms must adhere to federal regulations including those in the Magnuson-Stevens Fishery Conservation & Management Act, the Endangered Species Act, the National Environmental Policy Act, the Clean Water Act, and the Marine Mammal Protection Act.

Farming Methods

  • Seed Production:
    • Wild sugar kelp is harvested to extract spores for culture.
    • Spores are settled onto nylon twine wrapped around a PVC pipe (or spools).
    • Once spores have settled after 24-36 hours, the spools are placed in indoor tanks under controlled conditions.
    • After 4-6 weeks, the juvenile kelp plants are transferred to the grow-out site.
  • Grow out:
    • The seed string with juvenile plants attached is deployed in tanks or on long lines (a heavier culture rope suspended between buoys) in marine waters.
    • Sugar kelp is harvested when it reaches the appropriate size for its intended purpose.

The Science

Environmental Considerations

  • Habitat:
    • Sugar kelp farming has a benign ecological footprint, with little disturbance of sediments or aquatic vegetation during grow out. It may cause some shading of the seafloor environment depending on the depth in which it is grown. 
    • Seeding is a quick process accomplished from small skiffs and harvesting is also quick and efficient consisting of bringing a long line onto the boat and removing the kelp with a small knife; both of these operations are low impact on the environment.
  • Feeds:
    • Once transferred to the ocean site, sugar kelp does not need to be fed due to photosynthesis

Ecosystem Services‎

  • Water quality improvements:
    • Sugar kelp consume excess nutrients and carbon dioxide from the water column and give off oxygen as they grow, improving water quality of the surrounding environment.
    • When sugar kelp is harvested, excess nutrients, such as nitrogen and phosphorus, as well as carbon dioxide are removed from the ecosystem.
  • Providing habitat:
    • Sugar kelp provides structure and shade for many marine organisms and serves as habitat for juvenile fish and small invertebrates.
    • Sugar kelp beds also disperse wave energy to protect shorelines from erosion.

Human Health

  • Sugar kelp toxins:
    • Sugar kelp can assimilate toxins like heavy metals such as mercury present in the water where they are grown, but levels are extremely low making it safe at quantities typically consumed. 
    • Early warning systems exist to detect harmful algal blooms that produce toxins.
    • New technologies, such as the Environmental Sample Processor, provide near real-time detection of harmful algal species.
    • For more information on identification, prevention and monitoring of harmful algal blooms, read about the NOAA Ocean Service Harmful Algal Bloom programs.
  • Pathogenic bacteria:
    • Bacteria like Vibrio and salmonella can be found in contaminated water where farmed sugar kelp may grow.
    • Ingestion of sugar kelp contaminated with salmonella or other bacteria can lead to gastrointestinal illness.
  • Sugar kelp is required to be tested for toxins and bacteria and public health officials monitor farmed sugar kelp to ensure it is safe to eat.

Physical Description

  • Sugar kelp are yellowish or dark-brown and green in color.
  • They resemble large lasagna noodles and have a long narrow, undivided blade with a short thin stem. 
  • The central band of the blade is dimpled while the margins are smoother with a wavy edge. The crinkled blade gives the sugar kelp it’s other common names.


  • Sugar kelp reach maturity between 3 and 4 years of age. 
  • Their blade can grow up to 5 meters (16 feet) long and 20 centimeters (7.9 inches) wide.
  • Sugar kelp can live for 2-4 years and grow quickly in colder months.


  • Ocean acidification:
    • Acidification causes a number of changes in water chemistry that may be stressful to estuarine organisms.
    • In 2015, the Puget Sound Restoration Fund, NOAA, and other partners received $1.5 million from the Paul G. Allen Family Foundation to tackle the impacts of ocean acidification using sugar kelp.
    • Growth and Genetics:
    • The Northeast Fisheries Science Center’s Milford Lab is studying different aspects of sugar kelp to help commercial growers expand their operations.
    • In early 2017, researchers tested the lab’s sorting flow cytometer. The instrument will allow high-volume screening of individual kelp plants for desired traits such as high-temperature tolerance. This method may be used in the future for improving sugar kelp strains.
  • Human Health:
    • Milford Lab scientists, through a grant from the NOAA Aquaculture Program, are also studying different kinds of organisms like bacteria, micro-and macro-algae that may be growing on the surface of sugar kelp at different stages of the kelp’s growth. They isolated Vibrio bacteria from the plant to see how abundance changes throughout the growing season. They have found that Vibrio is absent during most of the growing season since this bacteria prefers warmer waters. This information can help growers harvest in the best possible conditions.
  • Energy:
    • One of the Milford Lab’s sugar kelp collaborators also received $5.7 million in 2017 from the Department of Energy through the agency’s program focused on advancing seaweed energy production, Macroalgae Research Inspiring Novel Energy Resources (MARINER). The grant to Woods Hole Oceanographic Institution will fund a selective breeding program for sugar kelp and an autonomous underwater observation system to advance the mass production of seaweed for biofuels and bio-based chemicals.

Last updated: 06/25/2020