Red Sea Urchin

The Science

Among their spines, urchins have two other types of arms: suctioning tube feet and claw-like pedicellaria used to grab food, move and clean themselves. Look closely!

The Fishery

The California sea urchin fishery began in 1970 and most were exported to Japan until ca. 2000, when the Japanese economic bubble burst and sea urchins became popular in domestic markets.

The Seafood

Fishermen can predict the quality of sea urchins by “reading the bottom”, or assessing habitat conditions such as food supply, water movement, replenishment of sea urchins.

The Science

Red Sea Urchin
Sally Anderson/CC BY-NC 4.0

Taxonomic description

  • An echinoderm, in the marine invertebrate group along with sea stars, brittle stars, and sea cucumbers.
  • This largest species of sea urchin can grow to be 18 cm (7”) diameter with spine lengths of 8 cm (3”) [1].
  • Recognizable by its dark red almost black body color and large spines.  

Distribution

  • Found on the west coast of North America as far south as the tip of Baja California, Mexico [2,3]

Life history

  • Spawns year round and peaks June -- November in San Diego [3].
  • When eggs are fertilized they develop into free-swimming larvae for 6-8 weeks until they settle to the sea floor and become juveniles [1]
  • Larval and juvenile growth rates depend on water temperature.
  • Can live 200 years [4] but most don’t

Habitat

  • Lives from lower rocky intertidal to depths of 160 m (525 ft).
  • Major food source is kelps, so is common in kelp forests
  • In San Diego, main predators include spiny lobster & California sheephead [2]; north of Pt. Conception main predator is the sea otter.
  • Sensitive to water temperature changes as well as low salinity.
  • Sea urchin feeding removes giant kelp so it can structure the whole forest ecosystem.

The Fishery

Pete Halmay

Seasonal availability

  • In California, available year-round with reduced effort Mon-Thurs from April-Oct[6]

Managing authority

  • California Department of Fish & Wildlife regulates the fishery
  • California Sea Urchin Commission represents interests of California’s sea urchin divers; operates under state law to ensure environmental, economic and social sustainability of the fishery.

Gear type

  • Fishers use hookah lines for diving to depths of 12-33 m (40-110 ft)
  • Collected by hand from crevices using a rake and placed in a collection basket
  • In So. California, red sea urchins must have a minimum test diameter of 3.25” (8.2 cm)

Status of the fishery

  • LIttle sustainability concern for local stocks at current level of exploitation & productivity
  • Current efforts partner scientists & local fishers to expand monitoring & attain a “profitable, sustainable, locally managed fishery”[8]
  • In 1987, after a 1970’s State control effort that left~75% of urchin population depleted in California[2], the industry initiated a moratorium on the fishery, including limited entry, seasonal closures & minimum size limits.
  • Despite there being only 18 urchin divers in San Diego with an average age of over 50yr, no new dive permits can be issued at this time

Potential ecosystem impacts

  • Minimal impacts when the management strategy considers: (a) amount of sea urchin relative to kelp biomass. E.g., the local fishery may limit population booms that form sea urchin barrens, areas where all of the kelp has been eaten. (b) the harvest of only high quality (“fat”) sea urchins (≤50% of total), which leaves plenty behind to function in the ecosystem and “fatten up”.
  • In areas with limited rocky substrate, juvenile urchins may depend on the spines of larger, adult urchins for shelter [4] so high harvest rates may affect sea urchin recruitment in these conditions.

The Seafood

Kristen Goodrich, sandiegobaci.com

Edible portions

  • The gonads of both male and female red urchins are a culinary delicacy, known as either “roe,”“uni” or “ricci del mar.”
  • Gonad quality is ranked on the size, color, texture, taste, and firmness [11]

Description of meat

  • Roe, or uni, has smooth, buttery texture with a sweet, complex taste

Culinary uses

  • Local sea urchin is mostly available live or fresh.
  • Cleaning and cracking the test (the shell) is manageable. Instructions can be found in multiple online resources  (e.g., [14])
  • Sea urchin can prepared many ways: Freshly cracked & eaten from the test, as sushi, like caviar on pasta, rice, seafood, crackers & cheese, as a flavor enhancer in soups, custards, and pasta dishes[2]

Nutritional information  

  • Sea urchin raw (3.5 oz) [12,13]
  • Omega 3 fatty acids 1.83 grams
  • Zinc 17.00 ppm

Toxicity report

  • No known toxins

Seasonal availability

  • Year round

References

[1] Red Sea Urchins, Mesocentrotus franciscanus ~ MarineBio.org." MarineBio Conservation Society. Web. July 8, 2013. < HYPERLINK "http://marinebio.org/species.asp?id=45"http://marinebio.org/species.asp?id=45>. Last update: 1/14/2013

[2] Tegner, M. J., P. K. Dayton. 1981. Population structure, recruitment & mortality of two sea urchins (Strongylocentrotus franciscanus and S. purpuratus) in a kelp forest. Mar Ecol Prog Ser 5: 255-268.

[3] Kato, S, S.C. Schroeter. 1985. Biology of the Red Sea Urchin, Strongylocentrotus franciscanus, and Its Fishery.  California. Marine Fisheries Review 43: 1-20.  HYPERLINK "http://spo.nmfs.noaa.gov/mfr473/mfr4731.pdf"http://spo.nmfs.noaa.gov/mfr473/mfr4731.pdf

[4] Ebert, T. 2003. Red sea urchins found to live up to 200 yrs. Science Daily  HYPERLINK "http://www.sciencedaily.com/releases/2003/11/031106051646.htm"www.sciencedaily.com/releases/2003/11/031106051646.htm

[5]"http://w3.shorecrest.org/~Lisa_Peck/MarineBio/syllabus/ch7invertebrates/..."http://w3.shorecrest.org/~Lisa_Peck/MarineBio/syllabus/ch7invertebrates/...

[6]  California Fisheries Fund . 2009. California Sea Urchin. California Fisheries Atlas .California Fisheries Fund.  HYPERLINK "http://californiafisheriesfund.org/reso_atlas_urch.html"http://californiafisheriesfund.org/reso_atlas_urch.html.

[7] Good, D. 2012. Fishing with the Urchin King Pete Halmay. San Diego Magazine.  HYPERLINK "http://www.sandiegomagazine.com/San-Diego-Magazine/June-2012/The-Urchin-..."www.sandiegomagazine.com/San-Diego-Magazine/June-2012/The-Urchin-King/.

[8] California Ocean Protection Council. Nov 2008. The San Diego Sea Urchin Project.  HYPERLINK "http://www.opc.ca.gov/webmaster/ftp/project_pages/CA_Fisheries/SDWA_Fina..."www.opc.ca.gov/webmaster/ftp/project_pages/CA_Fisheries/SDWA_Final_Repor....

[9] Nishizaki M.T., D.J. Ackerman. 2004. Juvenile-adult associations in sea urchins Strongylocentrotus franciscanus and S. droebachiensis: Is nutrition involved? Marine Ecology Progress Series 268: 93-103.

[10] Halmay, Pete. "San Diego Sea Urchin Fishery." Personal interview. 12 July 2013.

[11]  Leet, W.S., C.M. Dewees, R. Klingbeil, E.J.Larson, eds. 2001. California's Living Marine Resources: A Status Report. California Dept of Fish and Wildlife. HYPERLINK "http://www.dfg.ca.gov/marine/status/status2001.asp" www.dfg.ca.gov/marine/status/status2001.asp.

[12] Fat Secret: All Things Food and Diet. 2013. Uni (sea urchin).  HYPERLINK "http://www.fatsecret.com/diary.aspx?pa=fjrd&rid=1948231"www.fatsecret.com/diary.aspx?pa=fjrd&rid=1948231

[13] Pacific Urchin Harvesters Association. 2013. Sea Urchin Nutritional Information.  HYPERLINK "http://puha.org/assets/sea-urchin-nutritional-information.asp"http://puha.org/assets/sea-urchin-nutritional-information.asp>.

[14] Taste with the eyes. 2013.  HYPERLINK "http://www.tastewiththeeyes.com/2013/03/do-you-know-how-to-clean-a-sea-u..."www.tastewiththeeyes.com/2013/03/do-you-know-how-to-clean-a-sea-urchin/.