Brown Box Crab

The Science

Brown box crab is a type of king crab like the better known Alaskan king crab. 

The Fishery

Incidental catch in the Southern Rock Crab Trap fishery along with Kellet’s whelk, octopus, and other non-Cancer crabs [6] 

The Seafood

San Diego fishermen are building a market for this delicious species, which has been traditionally used as bait [6]. 

The Science

Brown Box Crab
Evelyn Ngo

Taxonomic description

  • Carapace up to 15 cm (6 in.) across; red-brown or tan in color, with white and purple patches, and small spines [2,3]
  • When disturbed, box crabs fold their legs and abdomen tightly together, so they appear like a tight box or ball [2]
  • Calcified abdomen, with relatively short legs [2]; the box crab’s fifth pair of legs are small and folded under the carapace, making it seem as if it only has four pairs of legs [2,7]
  • While buried, two circular holes (foramins) in the claws allow for water circulation to the gills [2]; this is a distinctive feature of this crab [2]
  • The large claw, usually the right, has blunt white teeth, while the small claw has sharp teeth [2].

Distribution

  • Extends from Kodiak Island, Alaska, to San Diego, California [3]

Life history

  • Lives in aggregations, move together, and molt at similar times within the aggregation [7]
  • In British Columbia, has a biennial (two-year) brooding cycle; females molt and breed in mid-summer, brood eggs and larvae for 18 months, and release zoeae over ~69 days during the second winter /early spring (Feb-April) after breeding [2]; life cycle may be shorter and brooding may begin earlier (February) in Southern California [7,9]
  • Pass through four larval stages before becoming juveniles and gaining the ability to walk [2]

Habitat

  • Low intertidal to ~600 m (1968 ft)  [2,3], but usually deeper than 18 m on muddy bottoms or on rocky faces over mud [2].
  • Scoops up mud to feed on bivalves and organic debris [3]; also feeds on brittle stars and sea urchins.
  • Preyed upon by octopus [2].
  • Commensal (potentially parasitic) organisms include snailfish, whose eggs and larvae can be found on crab gill filaments; and polychaete tubeworms, hydrozoans, and small bivalves on brooding and post-brooding females [2,8].

The Fishery

Brown Box Crab fishery
Evelyn Ngo

Seasonal availability

  • Year round.

Managing authority

  • California Department of Fish and Wildlife as incidental catch in the Southern Rock Crab Trap Fishery.

Gear type

  • Trap caught [7].

Status of the fishery

  • Fishery first began in response to a drop in the abundance of Dungeness crab, and a rise in price for crab, in the early 1980s [7,9]
  • No specific regulations for this species, but the fishery has limited entry and restricted access permits [5]
  • Little known about population size [5]

Potential ecosystem impacts

  • Unwanted species in traps are easily removed without injury and returned to the sea alive; Because traps are sedentary on the seafloor, little damage to the habitat occurs [4]

The Seafood

Brown Box Crab seafood
Evelyn Ngo

Edible portions

  • Meat inside the claws and legs [9].

Description of meat

  • Soft, buttery, and flakey

Culinary uses

  • Usually cooked whole, by steaming or boiling; about 25% of total weight is edible meat [9].
  • When steaming, place the crab on its back, with its claws and legs in the air.
  • Meat can be used in soups and chowders, crab cakes, or simply on its own with mild seasonings such as salt and pepper.

Nutritional information 

  • Nutritional information for slender crab could not be found; shown is Dungeness crab [10] 

Toxicity report

  • Domoic acid, a naturally occurring biotoxin in California crabs, can occasionally occur in the guts of crab during a massive harmful algal bloom. Check for warnings before buying fresh, and be sure to clean out guts before preparing.

Seasonal availability

  • Available year round.

References

[1] Guinan, J., R. Curtis, 1971. A Century Of Conservation. NOAA 1(2): 40-44.

[2] Cowles, D., 2008. Invertebrates of the Salish Sea: Lopholithodes foraminatus. Web. https://inverts.wallawalla.edu/Arthropoda/Crustacea/Malacostraca/Eumalac.... Accessed: 27 May 2017.

[3] NOAA Fisheries Alaska Fisheries Science Center. Web. https://www.afsc.noaa.gov/kodiak/photo/crabboxa.htm. Accessed: 27 May 2017.

[4] Tuna Harbor Dockside Market. Web. http://thdocksidemarket.com/new/. Accessed 28 May 2017.

[5] California Department of Fish and Wildlife. Web. https://www.wildlife.ca.gov/Licensing/Commercial/Descriptions. Accessed 28 May 2017.

[6] Major, D. 2017. Interview with San Diego Commercial Fisherman, Dan Major. F/V Plan B. San Diego, California. 29 April 2017.

[7] Zhang, Z.Y., et al. 1999. A Review of the Biology and Fisheries of the Box Crab (Lopholithodes foraminatus Stimpson) in British Columbia. Fisheries and Oceans Canada. Available: http://www.dfo-mpo.gc.ca/Library/240697.pdf.

[8] Peden, Alex E., and Cathryn A. Corbett. 1972. Commensalism between a liparid fish, Careproctus sp., and the lithodid box crab, Lopholithodes foraminatus. Can. J. Zool. 51: 555-56.

[9] Kato, S. National Marine Fisheries Service. 1992. Underutilized Species: Box Crab. Available: https://swfsc.noaa.gov/publications/CR/1992/9248.PDF

[10] Dungeness Crab,Web. Nutritionvalue.org. Accessed: 21 September 2017.