Description: A deep sea crab, dark red to light brown. It is the largest crab of the family Geryonidae. Smooth hexagonal shaped carapace with a rounded anterior part bearing five lateral spines. Strong chelipeds; long and slender walking legs. Mature males are larger than females and have larger chelipeds. Individuals are heterochelic, with a larger crushing chelae (usually the right one) and a minor tearing chelae.
Global Distribution: Northeastern Atlantic, from Iceland to the Canary Islands, mostly restricted to insular areas, seamounts and underwater ridges.
BIOLOGICAL FEATURES
Size: Maximum carapace length 189 mm (males), 165 mm (females). Maximum published weight: 970.0 g.
A minimum landing size of of 120 mm carapace width and 72 mm carapace length has been proposed.
Growth type: Canary Islands (Castro et al. 2010): Negative allometric growth pattern (carapace length vs. body weight); in some cases isometric (particularly in males). Azores (Pinho et al. 2001): Positive allometric.
von Bertallanfy growth parameters:
Reproduction: Reproduction seems to occur seasonaly and be a synchronous event. In Azorean waters, ovigerous females were found from October to March. In Madeira and the Canary islands, ovigerous females were found in the spring and summer, and high gonadosomatic index values from October onwards suggest an extensive spawning period from October to May.
Mating involves a pre-copulatory embrace during which the male protects the female while she moults, and copulation must occur before the female carapace hardens. Mating pairs in embrace position were observed at the interface of Mediterranean Outflow Water and North Atlantic Deep Water, at temperatures ranging from 8.5°C.
Recently (Hilário & Cunha 2013), a biennial reproductive cycle has been hypothesized with mating and gonad maturation taking place in the first year, and ovoposition, spawning, and a burst of somatic growth happening in the second year.
Maturity: Females: 83 - 97 mm carapace length; 109 cm carapace width.
Behavioural ecology:
Population structure & migrations: There appears to be some depth segregation by sex, but bathymetric distribution is dynamic and may change according seasonal migrations related to reproduction, and also to the presence of competitor crab species such as Cancer bellianus.
ECOLOGICAL FEATURES
Depth range: SeaLifeBase: 130 - 2047 m.
Azores (Pinho et al. 2001): 600 - 1100, most common between 600 - 700. Males relatively more abundant less than 800 m depth and females more abundant below that depth.
Habitat: Benthic on hard and soft substrates on the upper slope. They have also been detected on seamounts and near hydrothermal vents.
Feeding habits: They were observed feeding on mussels.
Trophic level:
FISHERIES
Commercial interest: Commercial species. Not currently exploited in Madeira, but experimental fisheries have shown it to have potential commercial interest in the region. However, more studies are needed to assess its sustainability.
Conservation status: Not evaluated.
Nutritional information & food safety:
Proximate composition per 100 g:
energy value 113.47 kcal (5.7% DRV)
protein 18.23 g (36.5% DRV)
fat 0.73 g (1.0% DRV)
of which saturates 0.13 g (0.7% DRV)
omega-3 (EPA+DHA): 0.207 g (recommended: 0.250 - 2.0 g daily)
REFERENCES
Abellán L.J.L., BalguerÃas E., Fernández-Vergaz V. (2002). Life history characteristics of the deep-sea crab Chaceon affinis population off Tenerife (Canary Islands). Fisheries Research, 58: 231-239.
Biscoito M. (2006). Chaceon affinis "deep-sea red crab". In Desbruyères D., Segonzac M., Bright M., eds. Handbook of Deep-Sea Hydrothermal Vent Fauna, second edition. Denisia 18, Linz, Austria, 544 pp.
Biscoito M., Saldanha L. (2000). Occurrence of Chaceon affinis (Decapoda: Geryonidae) in the vicinity of a hydrothermal vent site on the Mid-Atlantic Ridge. Journal of Crustacean Biology, 20(1): 128-131.
Hilário A., Cunha M.R. (2013). Notes on a mating event of the deep-sea crab Chaceon affinis in the Gorringe Bank (NE Atlantic). Deep-Sea Research II, 92: 58-62.
IUCN (2014). The IUCN Red List of Threatened Species. Version 2014.1. www.iucnredlist.org
Pinho M.R., Gonçalves J.M., Martins H.R., Menezes G.M. (2001). Some aspects of the biology of the deep-water crab, Chaceon affinis (Milne-Edwards and Bouvier, 1894) off the Azores. Fisheries Research, 51(2): 283-295.
Robinson M. (2008). Minimum landing size for Northeast Atlantic stocks of deep-water red crab, Chaceon affinis (Milne Edwards and Bouvier, 1894). ICES Journal of Marine Science: Journal du Conseil, 65(2): 148-154.
