|Scientific Name:||Squalus blainville (Risso, 1827)|
Acanthias blainville Risso, 1827
Squalus blainvillei (Risso, 1827)
|Taxonomic Notes:||Squalus blainvillei was inadequately described and there are no type specimens. It is commonly confused with S. megalops and S. mitsukurii (Compagno pers. comm.). It has been identified by various authors as two or possibly three different species in the Northeast Atlantic and Mediterranean and possibly as more species elsewhere (Compagno in prep.). This species complex is in need of a critical revision of its systematic status.|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Ebert, D.A., Serena, F. & Mancusi, C.|
|Reviewer(s):||Cavanagh, R.D., Heupel, M.R., Simpfendorfer, C.A. & Valenti, S.V. (Shark Red List Authority)|
The Longnose Spurdog (Squalus blainvillei) is a benthic spurdog that may form a species complex. There are no type specimens and the species was inadequately described. It has been widely reported (with perhaps two or three different species involved in the eastern Atlantic), but the complex is in need of critical revision to define the species' true distribution. Like other squaloid sharks, this species is apparently ovoviviparous and may have life-history characteristics that make it more vulnerable to heavy fishing pressure. It is fished in the tropical eastern Atlantic and Mediterranean with bottom trawls, gillnets and line gear, where it is caught with a complex of other Squalus species, but due to problems with identification the level of catch is uncertain. The species is used fresh, salted, dried and smoked for human consumption. It is not possible to assess Longnose Spurdog beyond Data Deficient until the species has been critically revised and the taxonomic issues resolved. Resolution of these issues and the quantification of catch levels should be a priority.
|Range Description:||Undefined, due to taxonomic confusion with several different species. Nominally from eastern Atlantic and Mediterranean Sea: Mediterranean coast of France (type locality), possibly Republic of Congo, possibly Mozambique, possibly western Pacific off Japan, China and Taiwan Island, possibly Australia (New South Wales) (Compagno in prep).|
Nominal records from Bay of Biscay to Mediterranean and Black Seas, Morocco, Canaries, Senegal to Namibia are probably based on two or more species. There are also nominal records as S. blainvillei or S. fernandinus from the western and eastern Atlantic, western Indian Ocean, western and central Pacific, and eastern south Pacific but these are based in large part on S. mitsukurii or close relatives (Compagno in prep).
FAO fisheries areas: 27, 34, 37, 47, 51, 61.
Native:Albania; Angola; Benin; Bosnia and Herzegovina; Cameroon; Congo; Côte d'Ivoire; Croatia; Egypt; Equatorial Guinea; France (France (mainland)); Gabon; Gambia; Ghana; Greece; Guinea; Guinea-Bissau; Italy; Liberia; Libya; Montenegro; Morocco; Namibia; Nigeria; Romania; Senegal; Sierra Leone; Slovenia; Spain (Canary Is., Spain (mainland)); Togo; Tunisia; Turkey; Ukraine
|FAO Marine Fishing Areas:|
Atlantic – northeast; Atlantic – southeast; Atlantic – eastern central; Mediterranean and Black Sea; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Taxonomic confusion with several other species prevents accurate determination of population trends.|
Data from the Mediterranean International Trawl Survey program (MEDITS) (scientific trawl surveys undertaken since 1994 along the European Mediterranean coasts at depths of 10-800 m, 10,000 hauls) were analysed by Serena et al. (2005). Squalus blainvillei composed 3% of the total catch of elasmobranchs during this survey (1,500 tons out of a total 55,000 tons). This species appears less abundant than Squalus acanthias which composed 6,700 tons of the total catch. No more than 10% of the individuals of these species sampled weighed more than 2 kg.
It was no possible to determine the trend in abundance of this species in the Mediterranean Sea because the data are highly uncertain (Serena et al. 2005).
|Current Population Trend:||Unknown|
|Habitat and Ecology:||A benthic, rather sluggish species (Whitehead et al. 1984) living at or near muddy bottoms, nominally recorded from the continental shelves and upper slopes, at or near the bottom at depths of 16 m to at least 440 m and probably deeper (Compagno in prep.). Off West Africa it is reported on muddy bottom in water of 11-18°C and salinities of 36 parts per thousand (16-255 m depth) (Compagno in prep.). The species apparently ranges from depths of 50-700 m in the Mediterranean (Serena et al. 2005).|
Details on the biology of this shark are uncertain because of the taxonomic problems discussed above (Compagno in prep). The species is apalacental viviparous. In the eastern north Atlantic and Mediterranean nominal S. blainvillei is reported to form large schools (Compagno in prep).
Maximum total length of the large high-finned western north Pacific dogfish ascribed to this species by Chen, Taniuchi and Nose (1979) is at least 81 cm, about the same as a somewhat similar high-finned dogfish from Mozambique (Compagno in prep).
Detailed data on nominal S. blainvillei from the northeast Atlantic and Mediterranean is suspect because of confusion with two or more species (Compagno in prep.). Bauchot (1987) reports size at birth as 23 cm, with females maturing at 50-65 cm in total length (TL), and males at 45-50 cm TL. Data from about 119 specimens collected around Crete (Greece) estimated size at maturity as 52 cm for females and 47 cm for males (Chatzispyrou and Megalophonou 2005). In the Mediterranean, Bauchot (1987) estimated three to four pups per litter, while Whitehead et al. (1984) reported four to nine, with one litter produced every two years. The species apparently feeds on bony fishes, cephalopods and crustaceans (Bauchot 1987).
Taxonomic confusion makes it difficult to assess the full impact of threats on this species. Sharks referred to as S. blainvillei are fished with bottom trawls, gillnets and line gear in the tropical eastern Atlantic and Mediterranean, however the catch is probably multispecies and includes members of the S. megalops and S. mitsukurii groups (including high and low-finned species) (Compagno in prep.). Catch levels are uncertain due to identification problems.
Apparently regularly present in fish markets throughout Adriatic ports, including Sicily, Tunisia, Morocco, Greece, Turkey and occasionally elsewhere (Bauchot 1987), although difficulties with identification may pose a problem.
There is evidence for significant catches of Squalus species in the northeastern Mediterranean, particularly in the northern Tyrrhenian sea (Serena pers. obs. 2006). Squalus species are taken as bycatch of the bottom trawl fishery targeting red shrimps in the Strait of Sicily. About one third of the catch of this fishery is chondrichthyan bycatch, of which S. acanthias and S. blainvillei compose about 5% (Ragonese et al. 2000). In this area both dogfish, S. acanthias and S. blainvillei, are captured in significant numbers due to the good quality of their meat, which is marketed for human consumption (1,200 tons of Squalus species were landed in 1982) (Cingolani et al. 1986).
In the Black Sea S. acanthias and S. blainvillei are taken as bycatch by purse seines targeting pelagic fishes like anchovy, sardines and horse mackerel. The abundance of dogfish in these catches has displayed similar fluctuations to the targeted species. Dogfish catch has gradually decreased and reached 645 metric tons for Turkish area and 430 metric tons for the Black Sea. According to Serena et al. (2005) catch data indicate that the Black Sea and eastern Black Sea catches have decreased to 67% and 62%, respectively (Turkish State Statistics Institute 2004 In: Basusta et al. 2006).
Directed fisheries for S. acanthias undertaken during the 1970s in areas of the northwestern Mediterranean (off the Balearic Islands) have ceased as a result of declines in the stock of S. acanthias (Fordham et al. 2006). Squalus blainvellei is of limited fisheries importance compared to S. acanthias, but may also have been impacted by fishing pressure in this area.
|Conservation Actions:||None in place. Critical taxonomic revision of this species complex is required in the first instance to accurately define the distribution and make a full assessment of the population of this species.|
|Citation:||Ebert, D.A., Serena, F. & Mancusi, C. 2009. Squalus blainville. The IUCN Red List of Threatened Species 2009: e.T161536A5446109.Downloaded on 26 September 2018.|
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