Red Ogo Seaweed

The Science

When the complex sugar (polysaccharide) in the cell walls of this and other red algae is boiled, it produces agar, a gelatinous substance used as a food thickener.

The Fishery

Many other members of this genus, Gracilaria, are also collected and farmed for food and use as thickeners, especially in developing countries.

The Seafood

Eat with the fishes?! Red ogo seaweeds are not only popular with humans, they are also used for aquarium-fish food.

The Science

Hand holding red ogo seaweed
Carlsbad Aquafarm

Taxonomic description

  • Colored pale red to pinkish. [1,2]
  • Has a central axis from which up to 14 branches arise, each with 2-3 orders of branching. [2]
  • Slender branches, 1-3 mm (0.04- 0.12”) diameter. [1]
  • Grows to 30--70 cm (1-- 2.3 ft) tall. [2]
  • Used to be grouped with Gracilaria verrucosa. [2]


  • Found from Southern California to Alaska. [2]

Life history

  • Like many seaweeds, it has separate, free-living sporophyte (2n) and gametophyte (1n) stages. 
  • Each stage looks similar, with the female gametophytes most obvious when reproductive due to dark bumpy reproductive structures (cystocarps) on branches. [2]


  • Found on soft substrates, with fine to coarse texture. [3]
  • Infrequent, discontinuous distribution on coarse sand or rocks with the ability to form dense beds in some areas. [1,3]
  • Mostly found in sheltered water from subtidal to high intertidal elevations. [1,3]
  • Commonly grows in association with a closely related seaweed, Gracilaria lemaneiformis. [1]

The Fishery

Tubs set for aquaculture of seaweed
Carlsbad Aquafarm

Seasonal availability

  • Available May -- November.
  • Takes a few months to create a harvestable mass. [4]

Regulatory and managing authority

  • Growing methods & product are regulated by federal, state & local agencies (e.g., Army Corps of Engineers (lead), NOAA, U.S. Fish & Wildlife Service, US. Dept of Agriculture, Food & Drug Administration, County Dept of Public Health). 
  • California Aquaculture Association promotes sustainable commercial production of plants and animals by conserving California’s land & water.

Gear type

  •  Grown in onshore tanks containing seawater & exposed to natural sunlight. [4]
  •  In Hawai’i, a related species is grown in baskets at the surface of fish ponds where it can utilize excess nutrients. [5]

Status of the fishery

  • G. pacifica is native to this coast and it not currently under any threat of decline.
  • Abundant enough to form beds in some parts of its range, especially in response to nutrient addition.

Potential ecosystem impacts

  •  Aquaculture reduces the pressure on local natural populations and limits the need for imported seafood.
  •  No direct ecosystem effects of the gear except for the loss of upland habitat to make room for the tanks.
  •  Farming of this seaweed, as with most, improves water quality through the removal of nutrients.

The Seafood

Red ogo salad

Edible portions

  • Whole seaweed is eaten.

Culinary uses

  • Can be stored up to three days in a refrigerator in a covered container (do not place in water).
  • Dipping the seaweed into boiling water for approximately ten seconds diminishes saltiness and brightens color, but reduces crispiness. [7]
  • Is great marinated, added to salads, sandwiches or pastas, or in any dish as a substitute for lettuce.
  • Examples of dishes include seaweed and cucumber salad (with feta cheese and lemon) and healthy wraps with seaweed wrapped around rice, seafood or other meats. 

Description of seaweed 

  • Crispy texture with a slightly salty taste.
  • When fresh, the seaweed has a bright red color, however changes to dark green once cooked. [6]

Nutritional information  

  • Considered a “superfood” because it is high in important trace minerals, and potassium, iron, calcium, magnesium and iodine. [6] 
  • Information on 220g of fresh ogo can be found here. [8]

Toxicity report

  • There are no known contaminants.

Seasonal availability

  • Available farm fresh in San Diego May -- November.


[1] Abbott, I., G. Hollenberg. 1992. Marine Algae of California. Stanford University Press. 844 pp. (listed as G. verrucosa)

[2] Abbott, I.A. , J.N. Norris.1985. Taxonomy of economic seaweeds with reference to some Pacific and Caribbean species. California Sea Grant College Program.

[3] Schaeffer, K., K. McGourty, and N. Cosentino-Manning (eds.) 2007. Report on the subtidal habitats and associated biological taxa in San Francisco Bay. NOAA Santa Rosa Office.

[4] Carlsbad Aquafarm. Prod. Brian Robles and Cindy Kendrick. Green-Scene, 2013. YouTube. Web. Accessed 9 Sept 2020. 

[5] Glenn, EP, et al. 1998. A sustainable culture system for Gracilaria parvispora (Rhodophyta) using sporelings, reef growout and floating cages in Hawaii. Aquaculture 165: 221-232.

[6] Han, Emily. "Recipe: Red Ogo Seaweed Recipes." theKitchn. Apartment Therapy, 06 Aug 2008. Web. Accessed 13 Aug 2013.

[7] "Red Ogo Seaweed Information and Facts." Specialty Produce. Specialty Produce, 03 Sep 2011. Web. Accessed 13 Aug 2013.

[8] Seaweed-Ogo-Fresh. n.d. myfitnesspal. Web. Accessed 5 August 2020.