10030-3

Hexanchus griseus 

Scope: Mediterranean
Language: English
Status_ne_offStatus_dd_offStatus_lc_onStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Hexanchiformes Hexanchidae

Scientific Name: Hexanchus griseus (Bonnaterre, 1788)
Regional Assessments:
Common Name(s):
English Bluntnose Sixgill Shark
Synonym(s):
Hexanchus corinus Jordan and Gilbert, 1880
Hexanchus griseus (Bonnaterre, 1788) ssp. australis de Buen, 1960
Monopterinus griseus (Bonnaterre, 1788)
Notidanus griseus (Bonnaterre, 1788)
Notidanus monge Risso, 1827
Notidanus vulgaris Pérez Canto, 1886
Squalus griseus Bonnaterre, 1788
Squalus vacca Bloch and Schneider, 1801
Taxonomic Source(s): Weigmann, S. 2016. Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity. Journal of Fish Biology 88(3): 837-1037.

Assessment Information [top]

Red List Category & Criteria: Least Concern (Regional assessment) ver 3.1
Year Published: 2016
Date Assessed: 2016-03-25
Assessor(s): Soldo, A., Bariche, M., Buscher, E., Cook, S.F. & Compagno, L.J.V.
Reviewer(s): Walls, R.H.L. & Allen, D.J.
Contributor(s): Fordham, S.
Facilitator/Compiler(s): Walls, R.H.L.
Justification:
Mediterranean regional assessment: Least Concern (LC)

The Bluntnose Sixgill Shark (Hexanchus griseus) is a benthic, littoral, and semipelagic shark occurring in deep and shelf waters throughout the Mediterranean Sea. The species is caught as bycatch in deepwater fisheries but the level of interaction with fishing activity is believed to be negligible at this time owing to the wide depth range that exceeds the reach of fisheries and low occurrence in reports of catch and landings. The species' slow life history characteristics are therefore not interacting with any major threats that deem them a catalyst for the species' extinction risk at this time. The Bluntnose Sixgill Shark is assessed as Least Concern in the Mediterranean Sea. Nonetheless, monitoring population trends would benefit future assessments in order to determine ongoing stability under current or future levels of fishing pressure.

Geographic Range [top]

Range Description:The Bluntnose Sixgill Shark has been reported from continental shelf waters of the western and central Mediterranean Sea (Ebert and Stehmann 2013). On the Calabrian coast it is commonly found in both Ionian and Tyrrhenian waters (Sperone et al. 2012), and appears to be relatively abundant in the Adriatic Sea (Soldo 2006), especially in waters off Pescara (Italy) in the western Adriatic Sea (Cugini and De Maddalena 2003). Its depth ranges from the surface to 2,500 m.
Countries occurrence:
Native:
Albania; Algeria; Bosnia and Herzegovina; Croatia; France (Corsica, France (mainland)); Greece (Greece (mainland)); Italy (Italy (mainland), Sardegna, Sicilia); Libya; Malta; Monaco; Montenegro; Morocco; Slovenia; Spain (Baleares, Spain (mainland), Spanish North African Territories); Tunisia
FAO Marine Fishing Areas:
Native:
Mediterranean and Black Sea
Additional data:
Lower depth limit (metres):2500
Range Map:10030-3

Population [top]

Population:There is no information available pertaining to population size or structure in the Mediterranean Sea. The species has a stable trend in the Northeast Atlantic according to deepwater surveys off the Spanish coast, and deepwater fishing effort is much higher in the Northeast Atlantic than in the Mediterranean Sea. The ban on fishing below 1,000 m depth in the Mediterranean region coupled with the species' wide depth range mean that it occurs largely outside the reach of fisheries. Therefore, despite the lack of region-specific data it can be inferred from the Atlantic and suspected from its range than the Bluntnose Sixgill Shark population is stable in the Mediterranean Sea as well.
Current Population Trend:Stable
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:

This species has a wide bathymetric and geographic range, suggesting that it may be capable of long distance migration in the open ocean (Ebert and Stehmann 2013). The depth range of this deepwater shark extends down to at least 2,500 m on the upper continental slope (Ebert and Stehmann 2013). There are occasional and scattered reports from depths of 217706 m off southern Sicily and waters between Tunisia and Malta (Farrugio and Soldo 2013). Since the Bluntnose Sixgill Shark preys on conspecifics opportunistically, size segregation occurs by depth (Ebert 1994). Young tend to be found in shallow waters often just offshore and move into successively deeper waters as they grow. For example, in the Sea of Marmara, Turkey, adult individuals have been mostly captured over the deeper parts of shelf and upper slope in the north, whereas young individuals have been captured in shallower waters (Kabasakal 2003). Adults and sub-adults tend to follow diurnal patterns of vertical range, sitting deep on the bottom by day and coming toward or to the surface at night to feed. Research suggests that this shark lives and reproduces off the Algerian and Tunisian coasts (Capapé et al. 2003). Pupping grounds apparently occur on the upper slopes and outer continental shelves.

This live bearing with yolk sac shark produces large litters with 47108 pups that range from 6574 cm total length (TL) at birth. The reproductive cycle is possibly biannual with a 12 month resting period followed by 12 month gestation period (Ebert and Stehmann 2013). There is evidence of multiple paternities in this species with as many as nine males siring a single female’s litter (Larson et al. 2011). Males mature at ~315 cm TL and females at ~420 cm TL.

Systems:Marine
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade: The fish is taken in small-scale fisheries in parts of its Mediterranean Sea (e.g., around Sicily; Celona et al. 2005).

Threats [top]

Major Threat(s): This shark is taken as bycatch in handlines, longlines, gillnets, traps, trammel nets, and both mid-water and bottom trawls. There is some small-scales fisheries for this species in the Mediterranean (Celona et al. 2005).

Conservation Actions [top]

Conservation Actions: Croatia claims to strictly protect this and other elasmobranch species, although enforcement of this measure is unclear. There is a ban on deepwater fishing below 1,000 m depth in the Mediterranean Sea, which may offer this species refuge from fishing activity throughout much of its potential bathymetric range. Again, enforcement of this ban is still unclear.

Citation: Soldo, A., Bariche, M., Buscher, E., Cook, S.F. & Compagno, L.J.V. 2016. Hexanchus griseus. The IUCN Red List of Threatened Species 2016: e.T10030A16527980. . Downloaded on 17 December 2017.
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