Tasmanian giant crab explained

The Tasmanian giant crab (Pseudocarcinus gigas), also known as the giant deepwater crab, giant southern crab, queen crab, or bullcrab, is a very large species of crab that resides on rocky and muddy bottoms in the oceans off Southern Australia.[1] It is the only extant species in the genus Pseudocarcinus.[2]

Habitat

The Tasmanian giant crab lives on rocky and muddy bottoms in the oceans off Southern Australia on the edge of the continental shelf at depths of 20-.[1] It is most abundant at 110- in the summer and 190- in the winter.[1] The seasonal movements generally follow temperature as it prefers 12-.[1] The full temperature range where the species can be seen appears to be 10-.[3]

Description

The Tasmanian giant crab is one of the largest crabs in the world, reaching a mass of 17.6kg (38.8lb) and a carapace width of up to 46cm (18inches).[4] Among crabs, only the Japanese spider crab (Macrocheira kaempferi) can weigh more.[3] Male Tasmanian giant crabs reach more than twice the size of females,[5] which do not exceed 7kg (15lb).[4] Males have one normal-sized and one oversized claw (which can be longer than the carapace width[3]), while both claws are normal-sized in females.[4] This crab is mainly whitish-yellow below and red above; the tips of the claws are black.[6] Small individuals are yellowish-and-red spotted above.[3]

Behaviour

The Tasmanian giant crab feeds on carrion and slow-moving species, including gastropods, crustaceans (anomura and brachyura) and starfish.[1] [5] Cannibalism also occurs.[1] They breed in June and July, and the female carries the 0.5–2 million eggs for about four months.[5] After hatching, the planktonic larvae float with the current for about two months before settling on the bottom.[3] The species is long-lived and slow-growing; juveniles moult their carapace every three-four years and adult females about once every nine years.[3] [4] This greatly limits the breeding frequency, as mating is only possible in the period immediately after the old carapace has been shed, and the new is still soft.[4]

Fishery

The Tasmanian giant crab has been commercially fished in Tasmanian waters since 1992 and a minimum size was established in Australia in 1993.[5] Fishing is typically by pots in water deeper than 140m (460feet).[4] Following concerns surrounding the sustainability of catch numbers, the total allowable catch was adjusted for 2024/25 quota year to 20.7t.[7] valued at about A$2 million.[7] The Tasmanian giant crab is very long-lived and slow-growing, making it vulnerable to overfishing.[5] Before export, they are sometimes kept alive in tanks with water that is 10-.[1]

Notes and References

  1. Levings, A.H. & P.C. Gill (2010). Seasonal Winds Drive Water Temperature Cycle and Migration Patterns of Southern Australian Giant Crab Pseudocarcinus gigas. In: G.H. Kruse, G.L. Eckert, R.J. Foy, R.N. Lipcius, B. Sainte-Marie, D.L. Stram, & D. Woodby (eds.), Biology and Management of Exploited Crab Populations under Climate Change. .
  2. . 2008 . 17 . 1–286 . Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world . P. K. L. Ng, D. Guinot & P. J. F. Davie .
  3. Book: Poore, G.C.B. . 2004 . Marine Decapod Crustacea of Southern Australia: A Guide to Identification . 445 . CSIRO Publishing . 0-643-06906-2.
  4. Web site: Giant crab – a goliath amongst crustaceans . Tasmanian Museum and Art Gallery . Tasmanian Museum and Art Gallery . 2013-02-12 . Shaping Tasmania: a journey in 100 objects . Department of Economic Development, Tourism and the Arts. . 2024-08-13.
  5. Book: D. R. Currie & T. M. Ward . 2009 . South Australian Giant Crab (Pseudocarcinus gigas) Fishery . Fishery Assessment Report for PIRSA . . 9 December 2013.
  6. Book: Neville Coleman

    . N. Coleman . Neville Coleman . 1991 . Encyclopedia of Marine Animals . Blandford, Villiers House . 107. 0-7137-2289-4.

  7. Web site: Giant crab fishery . . 2024-08-13.