|Scientific Name:||Oxynotus centrina (Linnaeus, 1758)|
|Taxonomic Notes:||The Oxynotus recorded as O. centrina from Angola, Namibia, and South Africa may not be that species but an undescribed one, differing from O. centrina in having a much shorter interdorsal space. If this is correct, the records of O. centrina from tropical West Africa need to be reexamined, but until the problem is resolved the southern and southwestern African Oxynotus is retained in O. centrina (Bass et al. 1976).|
|Red List Category & Criteria:||Vulnerable A2bcd+4bd ver 3.1|
|Assessor(s):||Bradai, M.N., Serena, F., Bianchi, I. & Ebert, D.A.|
|Reviewer(s):||Dulvy, N.K., Cavanagh, R.D., Valenti, S.V. & Soldo, A.|
A medium-sized (to 150 cm but mostly <100 cm) deepwater, bottom dwelling shark distributed throughout the Eastern Atlantic and Mediterranean and possibly off Mozambique at known depths of 60 to 660 m. Taken primarily as bycatch by offshore bottom and pelagic trawlers in the Mediterranean Sea and the Northeast Atlantic. Survey data for the Mediterranean indicate that the species is now rare in the western (Morocco, Spain and France) and eastern (Aegean) areas and absent from the eastern central area (Adriatic, Ionian and Albania). However, records in the Adriatic and Ionian, suggest that the species still exists there in unknown numbers. In another survey, the species was also absent in the Gulf of Lions where it once occurred, indicating that it may be locally extinct in that region. The large spiny dorsal fins and relatively large body size make this species particularly vulnerable to capture in nets and its depth distribution lies entirely within the depth of fisheries throughout much of its range. The mortality of discards is likely to be high given the depths of capture. The current extremely low level of abundance throughout much of this species former range, and evidence for local scale declines, suggests an assessment of Critically Endangered in the Mediterranean. Off southern Africa, O. centrina is only known from a few specimens. It may occasionally be caught as bycatch in trawl fisheries there, but at present it is not possible to assess this species beyond Data Deficient in this region. Data are lacking on population trends in the Northeast Atlantic, however, given the high fishing pressure throughout much of its range in the Northeast Atlantic, the growing trend in deep sea fishing, the vulnerable life-history characteristics, and susceptibility to capture, there is no reason to suspect that it has not also declined in this region. Based on the species unproductive life history characteristics and documented declines in the Mediterranean as well as inferred declines in the Northeast Atlantic, and continuing fishing pressure through much of its range, the species is assessed as Vulnerable globally, on the basis of suspected and documented past and future declines.
|Range Description:||Eastern Atlantic and Mediterranean (entire coast from Straits of Gibraltar to Israel, but absent from the Black Sea), down to South Africa. Possibly off Mozambique in the Indian Ocean (Compagno in prep).|
Native:Albania; Algeria; Angola; Bosnia and Herzegovina; Croatia; Cyprus; Egypt; France; Gabon; Greece; Guinea; Israel; Italy; Lebanon; Liberia; Libya; Malta; Mauritania; Monaco; Namibia; Nigeria; Norway; Portugal (Madeira); Senegal; Slovenia; South Africa (Western Cape); Spain (Canary Is.); Syrian Arab Republic; Tunisia; Turkey; United Kingdom (Great Britain); Western Sahara
|FAO Marine Fishing Areas:|
Present - origin uncertain:
Atlantic – northeast; Atlantic – southeast; Atlantic – eastern central; Indian Ocean – western; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Relatively wide ranging. Rare in some parts (e.g., Angola, Atlantic coast of South Africa) and uncommon in others (northern Namibia, Mediterranean Sea) (Compagno in prep).
Catch data for O. centrina in the Mediterranean exists for the period from 1994 to 1999 (at depths from 10 to 800 m) as part of the Mediterranean International Trawl Survey (MEDITS). During this period, O. centrina was recorded in only 0.6% of tows, with the majority of catches made at between 100 to 200 m depth (STECF 2004). Regional biomass indexes indicate that the species is more common in the western central Mediterranean (Tyrrhenian, Corsica, Sardinia, Sicily) with a lower biomass index in the western (Morocco, Spain and France) and eastern (Aegean) Mediterranean areas. During these surveys, it was found to be absent from the Eastern central Mediterranean (Adriatic, Ionian and Albania) (STECF 2004).
Trawl surveys in 1948 indicated that the species was once present, though uncommon (0.21 % of hauls, 0.25% of surveys, estimated density of 1.15 kg km-2) in the Adriatic and the absence of the species in subsequent MEDITS surveys suggests that it may be locally extinct from the area (Dulvy et al. 2003). However, there have been recent records of juveniles caught in the central Adriatic (Lipej et al. 2004, A. Soldo pers. comm). Also, data collected during other (DESEAS) surveys of the Balearic Sea and Ionian Sea found one specimen in the western Ionian Sea at 800 m (Sion et al. 2004). Apparently then, O. centrina still exists in the Eastern central Mediterranean in unknown numbers.
Between 1957 and 1960 O. centrina was captured in approximately 6% of hauls (n=27) in shelf surveys (coast to 150 m) and in approximately 6% of hauls (n=37) in slope surveys (150 to 800 m) in the Gulf of Lions, France (Aldebert 1997). Although it persisted in catches at low abundance up to 1992, it was subsequently absent in 139 hauls made during a trawl survey spanning 1994 to 1995 (Aldebert 1997), suggesting that the species is locally extinct from this area (Dulvy et al. 2003). MEDITS data for the period from 1994 to 1999 found lower abundances in the west than in other areas of the Mediterranean, although the species was present (STECF 2004).
This species was absent in a recent and intensive study of the deepwater longline fishery for sharks off the Canary Islands, where it was previously present (Hernandez et al. 1997). There is no information on the abundance of this species elsewhere in the region.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This species is found from 60 to 660 m depth (Serena 2005), but mostly below 100 m. Sion et al. (2004) stated a record of one specimen caught at 800m of depth. Found on coralline and muddy bottoms, mostly between 100 and 200 m depth in the northern Mediterranean sea. |
Size at maturity has been reported at between 50 and 70 cm (Serena 2005) and Capapé et al. (1999) reported that a larger size at maturity in females (66 cm) than in males (60 cm). The species reaches a maximum size of 150 cm TL (Serena 2005, Compagno et al. 2005) although Compagno (in prep.) notes that most individuals are less than 100 cm. Indeed, Capapé et al. (1999) reported maximum lengths of 64 cm and 78 cm for males and females respectively.
Ovoviviparous, producing litters of 10 to 12 pups once a year (Capapé et al. 1999). Size at birth has been reported between from 21 to 24 cm [or <25 cm (Compagno et al. 2005)] with an average of 22.83 cm (Capapé et al.1999).
Feeds on polychaetes, crustaceans and molluscs (Compagno in prep).
Primarily caught in the Mediterranean Sea and the Northeast Atlantic as a minor bycatch by large offshore bottom and pelagic trawl fleets (Compagno in prep). Mediterranean Benthic trawl effort has increased in both intensity and efficiency in the shelf and slope area of the Mediterranean over the last 50 years. For example, the Gulf of Lions area was initially exploited by small-scale benthic trawl fisheries, comprising 27 small low powered boats (total nominal horse power of 2,700 hp), and more recently effort has increased to a total nominal horse power of 19,940 hp (1974 to 1987). Since then half of the fishing effort has been displaced to targeting small pelagic fish (Aldebert 1997). The Adriatic Sea is subject to trawling mainly by Italian, Croatian, Slovenian, and Albanian fleets, however, no landings data are available (Jukic-Peladic et al. 2001). In the southern Mediterranean and off the Tunisian coasts this species is fished at depths of 60 to 100 m, where it reproduces (Bradaï et al. 2002). It is considered rare in Tunisian waters and is taken as bycatch with no economic value (M.N. Bradaï pers. obs). Most size classes are likely to be taken in fishing nets as the legal mesh size used in much of the Mediterranean is approximately 20 mm. Considering the large size at maturity (around 60 cm total body length), the exploitation of juveniles and probability of capture before breeding is likely to be high. The depth range of this species (60 to 660 m) lies entirely within the range of deepwater fisheries in the Mediterranean. Therefore it will not be protected by the ban on bottom trawling below depths of 1,000 m in the Mediterranean, adopted by the General Fisheries Commission for the Mediterranean (GFCM) in February 2005. According to Dulvy et al. (2003) the large spiny dorsal fins and relatively large body size, may make this species vulnerable to fishing exploitation, however Serena (pers. obs.) has commented that the species is of no commercial value in the Mediterranean and is usually discarded immediately because fishermen in the region believe that it brings bad luck. Discards have sometimes been observed alive (Serena pers. obs.), however, there are no data on the post release survival of the species and mortality is likely to be high given the depth at capture.
It is widely acknowledged that there has been a fairly rapid increase in deepwater fishing activities in the Northeast Atlantic with overall concern for the sustainability of deepwater fish stocks (Gordon et al. 2003). Oxynotus centrina is known from depths which are entirely within the range of several longline, trawl and gillnet fisheries operating throughout the Northeast Atlantic distribution of the species. The species has already been shown to be vulnerable to being taken as bycatch in the Mediterranean and is also likely to be subject to bycatch pressure in the Northeast Atlantic. There is a continuing trend of increasing deepwater fishing activities in the Northeast Atlantic, while regulation is often lagging. Deepwater sharks are potentially at risk from these activities although little species-specific information is available. Oxynotus centrina may also be caught occasionally as bycatch in trawl fisheries off South Africa but there are insufficient data to support this and the taxonomy of specimens caught there remains uncertain.
|Conservation Actions:||There is an urgent need for the monitoring of landings and bycatch of this species and the collection of distribution and life history data in order to better understand the population structure and trends. The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and sustainable management of all chondrichthyan species in the region.|
Aldebert, Y. 1997. Demersal resources of the Gulf of Lions (NW Mediterranean). Impact of exploitation on fish diversity. Vie et Millieu 47: 275–284.
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Bass, A.J., D'Aubrey, J.D. and Kistnasamy, N. 1976. Sharks of the east coast of southern Africa. VI. The families Oxynotidae, Squalidae, Dalatiidae and Echinorhinidae. South African Association of Marine Biology Research, Oceanography Research Institution Investigatory Report No. 45:103.
Bradaï, M.N., Saïdi, B., Ghorbel, M., Bouaïn, A., Guélorget, O. and Capapé, C. 2002. Observations sur les requins du Golfe de Gabès (Tunisie méridionale, Méditerranée centrale). Mésogée 60: 65-78.
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Gordon, J.D.M., Bergstad, O.A., Figueiredo, I. and Menezez, G. 2003. Deep-water Fisheries of the Northeast Atlantic: I. Description and Current Trends. Journal of Northwest Atlantic Fisheries Sciences 31: 137-150.
Hernandez-Perez, M., Rabanal Gallego, R.M., Alayon, P.J.P. and Hernandez, A.B. 1997. Squalene content in livers from deep-sea sharks caught in Canary Island waters. Marine and Freshwater Research 48: 573-576.
IUCN. 2007. 2007 IUCN Red List of Threatened Species. Available at: www.iucnredlist.org. (Accessed: 12th September 2007).
IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.
Jukic-Peladic, S., Vrgoc, N., Krstulovic-Sifner, S., Piccinetti, C., Piccinetti-Manfrin, G., Marano, G. and Ungaro, N. 2001. Long-term changes in demersal resources of the Adriatic Sea: comparison between trawl surveys carried out in 1948 and 1998. Fisheries Research 53(1): 95–104.
Lipej, L., De Maddalena, A. and Soldo, A. 2004. Sharks of the Adriatic Sea. Knjižnica Annales Majora, Koper.
Serena, F. 2005. Field identification guide to the sharks and rays of the Mediterranean and Black Sea. FAO Species Identification Guide for Fishery Purposes, FAO, Rome.
Sion, L., Bozano, A., D'Onghia, G., Capezzuto, F. and Panza, M. 2004. Chondrichthyes species in deep waters of the Mediterraenan Sea. Scientia Marina 68(Suppl. 3): 153-162.
STECF. 2004. Commission Staff Working Paper: 17th Report of the Scientific, Technical and Economic Committee for Fisheries. Commission of the European Communities, Brussels.
|Citation:||Bradai, M.N., Serena, F., Bianchi, I. & Ebert, D.A. 2007. Oxynotus centrina. The IUCN Red List of Threatened Species 2007: e.T63141A12622296.Downloaded on 24 November 2017.|
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