|Scientific Name:||Hexanchus griseus (Bonnaterre, 1788)|
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.|
|Red List Category & Criteria:||Least Concern (Regional assessment) ver 3.1|
|Assessor(s):||Walls, R., Soldo, A., Bariche, M., Buscher, E., Cook, S.F. & Compagno, L.J.V.|
|Facilitator/Compiler(s):||Walls, R., Lawson, J. & Dulvy, N.|
European regional assessment: Least Concern (LC)
Bluntnose Sixgill Shark (Hexanchus griseus) is a deepwater, benthic, littoral and semipelagic shark. It is commonly caught in scientific surveys at the Porcupine Bank, Rockall, West of Scotland, in the Cantabrian and Galician Seas and North of the Azores, generally with stable catch trends in recent decades. This species is also caught as bycatch, and since the implementation of a zero Total Allowable Catch for deepwater sharks in European Union waters, discarding of this species has increased in the Azorean longline fishery and likely other fisheries throughout European waters. It has life history characteristics that make it sensitive to exploitation, but because there is no strong evidence of a historical decline and catch rates are low and stable in surveys, Bluntnose Sixgill Shark is assessed as Least Concern in European waters. Nonetheless, it should be monitored carefully because of its slow life history and potential for capture in deepwater fisheries.
This shark has a patchy range in boreal, temperate and tropical seas (Ebert and Stehmann 2013). In the Northeast Atlantic it is found as far north as Iceland, Faroe Islands, Norway, northern North Sea, Ireland, Scotland, England and Wales, and southwards towards France, Spain and Portugal, and the 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). In the Eastern Central Atlantic it is found in the waters surrounding the Azores and along the Mid-Atlantic Ridge. Its depth range is 217-2,500 m.
Native:Albania; Algeria; Belgium; Bosnia and Herzegovina; Croatia; Denmark; Faroe Islands; France (Corsica, France (mainland)); Germany; Greece (Greece (mainland)); Iceland; Ireland; Isle of Man; Italy (Italy (mainland), Sardegna, Sicilia); Libya; Malta; Monaco; Montenegro; Morocco; Netherlands; Norway; Portugal (Azores, Madeira, Portugal (mainland)); Slovenia; Spain (Baleares, Canary Is., Spain (mainland), Spanish North African Territories); Sweden; Tunisia
|FAO Marine Fishing Areas:|
Atlantic – eastern central; Atlantic – northeast; Mediterranean and Black Sea
This species represented a small percentage of relative abundance among all elasmobranchs caught during a Spanish survey at Porcupine Bank between 2001 and 2012 (ICES 2013). Biomass ranged between 0.5 and 1 kg per haul from 2001–2012 with an outlying peak in 2003 at 3 kg per haul. Estimates of relative abundance showed that between depths of 300-800 m less than one individual was encountered per hour on average (ICES 2013), suggesting no trend over the 14-year time series. Annual Spanish surveys of the Cantabrian Sea and Galician waters encountered this shark commonly in deeper hauls, but found this species was scarce or absent from the shallower catches. This survey showed that mean biomass has been stable from 1983–2012. Given the relatively deep range of this species, and the lack of trend in relative abundance and biomass in research surveys, it is estimated that the population is stable in European waters.
|Current Population Trend:||Stable|
|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 of this species at depths of 217–706 m in southern Sicily the area between Tunisia and Malta (Farrugio and Soldo 2013). Since this species 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, while 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 47–108 pups that range from 65–74 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 about 315 cm TL and females at about 420 cm TL.
|Use and Trade:||It is retained for human consumption in parts of the world, although this has not been reported in European waters.|
This shark is taken as bycatch in handlines, longlines, gillnets, traps, trammel nets, and both mid-water and bottom trawls. It is retained for human consumption in parts of the world, although this has not been reported in European waters. Discarding rates are increasing, and are likely linked to recently introduced management measures, particularly the total allowable catch (TAC), minimum size, and fishing area restrictions. Such restrictions have changed the fleet behavior, and have resulted in an expansion to offshore seamounts and deeper strata. In particular, between 2004 and 2010 this species was frequently caught and discarded by the Azorean longline fishery, potentially having a significant effect on the population (Pinho and Canha 2011).
Based on advice from the International Council for the Exploration of the Sea to end fishing for deepwater sharks, the European Union Fisheries Council established a TAC (Total Allowable Catch) in 2007 (CEC 2012), but did not include this species. This TAC was gradually reduced and in 2010 it was set at zero. In 2010 this species was added to this TAC, which covered a group of deepwater shark species. In 2011, the allowable bycatch was reduced from 10% to 3% of the 2009 TAC and in 2012 it was further reduced to zero (ICES 2013). Additional protection has been offered by Croatia, which proclaims this species as strictly protected, and by the North East Atlantic Fisheries Commission (Recommendation 7 in 2013) which required Parties to prohibit directed fishing for deepwater sharks, including this species. If deepwater commercial fisheries expand deeper in a species range they could pose a threat. Careful monitoring should be conducted for this species.
|Citation:||Walls, R., Soldo, A., Bariche, M., Buscher, E., Cook, S.F. & Compagno, L.J.V. 2015. Hexanchus griseus. The IUCN Red List of Threatened Species 2015: e.T10030A48939463.Downloaded on 14 December 2017.|
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