Purple Sea Urchin

The Science

Individuals in the intertidal decorate themselves with shells, rocks and pieces of algae as protection from sun and predators

The Fishery

Harvested as food in the 1990s, this species is now mostly harvested for scientific research

The Seafood

It is easy to spot sea otters that regularly eat purple sea urchin because their teeth turn purple.

The Science

Purple Sea Urchin
Drew Talley

Taxonomic description

  • Key identifying features are purple spines that protrude from a round body [3]
  • Size ranges from 5-10 cm (2-4 in) wide by 4 cm (1.6 in) tall [3]
  • Adolescents have mostly pale green spines that darken to purple as they mature [3]

Distribution

  • Eastern Pacific from Baja California, Mexico up the coast to Alaska [3]

Life history

  • Average lifespan is 20 years [4]
  • Seasonal breeder; January, February, and March are primary reproductive months [4]
  • The purple sea urchins are oviparous, where the development of the offspring occurs outside the mothers body [4]
  • Fertilized eggs settle on a substrate where it begins to develop [3]

Habitat

  • Rocky intertidal and kelp beds, founds in depths of up to 160 meters (525 ft) [4]
  • Water temperatures in excess of 22.8°C (73° F) increase mortality [3]
  • Primarily eats algae including giant kelp; predators include starfish, otters, and humans [4]
  • The primary natural predator, sea otter, is endangered which has allowed for a population boom and subsequent reduction in kelp in some areas [3]

The Fishery

Purple Sea Urchin
Sarka Martinez/CC BY-NC-SA 4.0

Seasonal availability

  • Available year round [3]

Managing authority

  • California Department of Fish and Wildlife (CDFW) is the ultimate decision making authority for the California Sea Urchin Fishery [3]
  • Managed by CDFW with the help of the California Sea Urchin Commission [9]

Gear type

  • Hand picked using SCUBA, and an urchin rake to collect urchin in mesh bags [1,2]

Status of the fishery

  • The California fishery was launched in the early 1990’s with export to Japan and the Mediterranean, where it is considered a delicacy [3,5], but shipping costs, and limited harvest areas and season (Sept-Oct) for high quality gonads made it not viable [2,10].
  • There are currently no major conservation efforts, with populations in some areas, such as Northern California, large enough to be suppressing kelp [4,10]
  • Fishery is small and predominantly in So. California aimed at scientific research demand [2,3], although efforts to renew the fishery in northern California are being considered to relieve grazing pressure on kelp [10]

Potential ecosystem impacts

  • Minimal environmental impacts due to hand harvesting methods.
  • Local harvest may limit urchin population booms form sea urchin barrens [8,10]

The Seafood

Bapak Alex/CC-BY-SA-3.0

Edible portions

  •  Gonads from females and males (that produce roe or milt) [6]

Description of meat

  • Color ranges from yellow to orange [7]
  • Soft and buttery with a sweet and salty deep ocean flavor [7]

Culinary uses

  • Eaten fresh or live from the shell [6]
  • Prepared raw, baked, sautéed, or steamed [6]
  • Commonly used in dishes such as sushi and pasta, but can be found in a variety of dishes and cuisines [6]

Nutritional Information 

  • A 100 g (3.5 oz )raw serving of roe is a good source of fatty acids, proteins, minerals, and vitamins [6,11]

Toxicity report

  • No known toxins [4]

Seasonal availability

  • Available year round in California [4]

References

[1] Alaska Department of Fish and Game. Commercial Dive Fisheries Sea Urchin Information., Web. www.adfg.alaska.gov/index.cfm?adfg=CommercialByFisheryDive.seaurchin . Accessed 10 May 2017.

[2] Halmay, P. 2017. Interview: Purple Sea Urchin. San Diego Commercial Fisherman, F/V Erin B. San Diego, CA 13 May 2017.

[3] Parker, D., Thomas E. 2002. Chapter 10. Purple Sea Urchin. Pages 10-1 to 10-4 In C. Ryan, M. Patyten (eds.) Annual Status of the Fisheries Report through 2003. California Department of Fish and Wildlife, Belmont, CA. Web. nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=34393&inline. Accessed: 21 Apr. 2017.

[4] Monterey Bay Aquarium. Purple Sea Urchin. Web. www.montereybayaquarium.org/animal-guide/invertebrates/purple-sea-urchin. Accessed: 6 Apr. 2017.

[5] Arkive. Purple sea urchin (Strongylocentrotus purpuratus). Web. www.arkive.org/purple-sea-urchin/strongylocentrotus-purpuratus/. Accessed: 5 May 2017.

[6] Pacific Urchin Harvesters Association. Sea Urchin Nutritional Information. Web. www.puha.org/assets/sea-urchin-nutritional-information.asp. Accessed: 10 May 2017.

[7] McDonnell, J.J. 2017. Sea Urchin. Web. www.jjmcdonnell.com/products/sea-urchin. Accessed: 10 May 2017.

[8] Worley, A. 2001. Strongylocentrotus purpuratus. Animal Diversity Web. animaldiversity.org/accounts/Strongylocentrotus_purpuratus/. Accessed: 5 May 2017.

[9] Greenberg, J. 2014. California Sea Urchin Commission. Web. http://www.calurchin.org/calurchin_index.html . Accessed 04 June 2017.

[10] Steele, B. 2017. Personal communication. California Commercial Fisherman. Santa Barbara, CA. 02 June 2017.

[11] Purple Sea Urchin,Web. Myfitnesspal.com. Accessed: 21 September 2017.