|Scientific Name:||Centroscyllium fabricii (Reinhardt 1825)|
Spinax fabricii Reinhardt, 1825
|Taxonomic Notes:||A comparison of Southeastern to North Atlantic specimens should be carried out to determine if both populations are the same species.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Ebert, D.A., Crozier, P. & Blasdale, T. & McCormack, C.|
|Reviewer(s):||Cavanagh, R.D., Heupel, M.R., Simpfendorfer, C.A., Acuña, E. & Valenti, S.V. (Shark Red List Authority)|
The Black Dogfish (Centroscyllium fabricii) is a relatively small (to at least 90 cm total length) deepwater, schooling shark of the outer continental shelf and slope found at depths from 180-2,250 m (mostly below 275 m). The species has a widespread but discontinuous distribution in the temperate Atlantic Ocean (tropical records are uncertain). The species' wide depth distribution affords it refuge from fishing pressure in many parts of its range, where deepwater fisheries are less developed. Recent population trends in parts of the Northwest Atlantic appear stable. Given stable population trends in the Northwest Atlantic and the species' relatively wide depth and geographic range, there is no reason to suspect that the global population has declined by approaching 30% and the species is assessed as Least Concern. However, deepwater fisheries are more developed and have a long history of operation across this species' range in the Northeast Atlantic, where it is taken as bycatch. Significant fishing pressure throughout much of the species' geographic and depth range in the Northeast Atlantic warrant a regional assessment of Near Threatened in this region, on the basis of suspected continuing declines approaching 30% (close to meeting VU A4bd).
|Range Description:||Northwest Atlantic: Greenland south to Canada (Baffin Island, Labrador, Newfoundland, and Nova Scotia), United States (Scotian Shelf south to Massachusetts, New York, New Jersey, Maryland, Virginia, possibly North Carolina and Gulf of Mexico off Alabama). |
Southwest Atlantic: Argentina (Beagle Channel).
Northeast Atlantic: Iceland along Atlantic Slope and including Iceland-Faroe Ridge, Faroes, southern Norway, Rockall Trough and Porcupine Seabight.
Eastern central Atlantic: Morocco, Mauritania, Senegal, Guinea and Sierra Leone.
Southeast Atlantic: Namibia and South Africa (west coast of Northern and Western Cape from the Orange River south to Cape Agulhas) (Compagno in prep.).
FAO Fishing Areas: 21, 41, 27, 34 and 47.
Native:Argentina; Canada (Labrador, Newfoundland I, Northwest Territories, Nova Scotia); Faroe Islands; Greenland; Guinea; Iceland; Mauritania; Morocco; Namibia; Norway; Senegal; Sierra Leone; South Africa (Northern Cape Province, Western Cape); United Kingdom (Great Britain, Northern Ireland); United States (Maryland, Massachusetts, New Jersey, New York, Virginia)
|FAO Marine Fishing Areas:|
Atlantic – northeast; Atlantic – northwest; Atlantic – southeast; Atlantic – southwest; Atlantic – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
Although not commonly encountered, the species is found on the slope from central Africa to Iceland (Kulka 2006). In Icelandic waters it is most abundant off the west, southwest and southeast coasts (Jakobsdottir 2001).
Exhibits size structure segregation by depth for both sexes off Iceland with the smallest immature specimens found at 1,000 and 1,500 m, and larger individuals at depths in between. The overall sex ratio off Iceland was 1.00:1.19 in favour of females. Males were more numerous in shallower waters but in depths >1,000 m, the sex ratio was significantly in favour of females (Jakobsdottir 2001).
The species is apparently abundant off southern Africa, mainly below 500 m depth. There is some uncertainty as to whether the Southeast Atlantic and the Northeast Atlantic populations are in fact the same species.
Abundant on the upper and middle slope and along the Mid Atlantic Ridge (Kulka 2006). Common off southwest Greenland (Yano 1995) and Baffin Island, in slope waters off Labrador, Newfoundland, the Scotian Shelf and Georges Bank (Kulka 2006). In the Northwest Atlantic Ocean Fisheries Organisation Regulatory Area (NRA), C. fabricii occupy an area of 225,000 km² and are highly abundant in the Laurentian Channel where they are 10 times more densely concentrated than in the Grand Banks or Labrador Shelf slope waters (Kulka 2006). Recent population trends of adults in the NRA have been stable (Kulka 2006).
According to Kulka (2006), in Canadian waters, large (pregnant) females migrate to the shallow (<400 m) portion of the Laurentian Channel where pupping occurs. The young then move into deeper waters of the channel. As they mature they move onto the slope, moving great distances north from the Grand Banks to the Labrador Shelf into deeper waters of the slope as they grow. The exception to this pattern is an area west of Greenland where juveniles of all sizes have been found in slope waters (Yano 1995). Kulka (2006) has suggested that there may be two separate stocks off Greenland and Canada even though the distribution is continuous between the two. Little information is available from the Southwest Atlantic at present.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Unless stated otherwise, this information is taken from Compagno (in prep.).|
A deepwater schooling shark of the outer continental shelf and slope found at depths from 180-2,250 m but mostly below 275 m. Off southern Africa the species is found from 275 to >1,300 m, but mostly below 500 m. In the Rockall Trough it has been recorded from the 1,250-1,500 m bathymetric zone (Mauchline and Gordon 1983). Off Iceland the species is most abundant between 800 and 1,200 m (range 436-1,653 m) (Jakobsdottir 2001). Off Greenland it is present from 338 to 1,299 m but more common below 500 m (Yano 1995) and in the NRA it is found from 400-1,400 m depth, with high concentrations between 350-500 m (Kulka 2006).
At high latitudes in the north Atlantic it may move near the surface, especially during the winter. In the boreal North Atlantic at the northern extremes of its range, this species does not extend into truly Arctic waters but occurs at the fringe. Most commonly caught at the bottom of the ocean where water temperatures usually range from 3.5-4.5°C, with a minimum of 1.0°C. In the NRA, the largest catches came from the warmest available locations (between 5 and 6.5°C), primarily in the Laurentian Channel (Kulka 2006).
Feeds on crustaceans, cephalopods, jellyfish, cod-like fishes and mackerel in the Northern Hemisphere. Off Namibia and the West Coast of South Africa it feeds primarily on crustaceans, especially penaeid shrimp but also euphausiids. Secondary prey includes cephalopods, lanternfish, barracudinas and unidentified teleosts (Ebert et al. 1992).
Reported size at maturity differs regionally (see Compagno in prep.; Yano 1995 and Jakobsdottir 2001) from around 51-70 cm and around 46-63 cm in females and males respectively. Maturity stages have been observed during two seasons indicating an undefined breeding season in Iceland waters (Jakobsdottir 2001).The species is ovoviviparous. Reports of litter size also range but has been reported at a mean of 16.4 (range 4-40) (Yano 1995). Size at birth has been reported from 15 cm (Compagno in prep.) and maximum size from 70 cm in South Africa (Compagno in prep.) to possibly 107 cm in the North Atlantic Ocean (Compagno in prep.). It is also sexually dimorphic; females grow to a larger size than males and are larger at first maturity.
The threat status of this species is of concern in the North Atlantic because of intensive fisheries operating on the deep slopes, following depletion of demersal fish stocks on the continental shelves and fishing-banks (Compagno in prep.). In the northeast Atlantic C. fabricii is frequently taken as bycatch in deepwater trawl and longline fisheries; however bycatch data is scarcely available.
ICES (2005) gives full description of the mixed trawl, deepwater gillnet and mixed and directed longline fisheries operating in the northeast Atlantic. Many of these fisheries operate throughout much of the species' geographic range in this area and bycatch pressure is likely to be significant. For example, off Iceland, a considerable amount of C. fabricii, are likely to be discarded by the commercial fishery for Greenland halibut Reinhardtius hippoglossoides. Records are rare and purely incidental, but Jakobsdottir (2001) estimated a bycatch of 98 and 109 t in 1996 and 1997 respectively based on trawl surveys in the area. Records of the catch proportions of the fleet in this area are needed for a full evaluation of the level of discarding of this species.
C. fabricii, are landed by the French trawl fishery for mixed deep-water species. Initially this fishery was conducted in ICES sub-areas VIa, VIIc,k but in 2001 when the Irish deep-water trawl fishery started to operate in Subarea VII most of the French fishing fleet moved to Subarea VIa (ICES 2005). In sub-area XII there have been some French landings of deep-water sharks, but it is not possible to detect any trends from the available data (ICES 2005). Note that this Sub-area contains both the western part of Hatton Bank and the Mid-Atlantic Ridge (ICES 2005) where this species is known to occur. Landings in France (mainly from division Vb and sub-area VI) decreased from about 250 t in 2000 to nearly 30 t in 2004 (ICES 2005). Iceland reported few landings from division Va and the largest annual landings reported by Spain came from sub-area XII in 2000 (85 Tonnes) and 2001 (91 tonnes) (ICES 2005).
Despite the more northerly distribution exhibited by this species, concerns still exist that this species will be vulnerable to the growing trend of the French deep-water trawl and other fisheries to operate in deeper waters to the west of the British Isles. Furthermore, there is still a lack of data available on incidental catches. Although C. fabricii has higher ovarian fecundities than other squalid sharks of its size, females still attain a large size at first maturity (Jones et al. 2005), and therefore this species may also be subjected to overfishing by the deep-water fishery.
The species is occasionally taken as a bycatch off southern Africa, but generally occurs in deepwater beyond the hake fishery zone. The species is not considered to be threatened in this region; however the situation should be monitored if fisheries expand into deeper waters. There is little information on catches of this species in the eastern central Atlantic.
In the northwest Atlantic, the species is taken as bycatch in a number of fisheries. In Canadian waters, there is no directed fishery but C. fabricii are taken as bycatch in a number of fisheries, primarily the Greenland halibut R. hippoglossoides, crab, redfish, monkfish and witch fisheries where removals averaged a total of 68t annually between 1996 and 2005 (Kulka 2006).
In the NRA, there are no data on removals but bycatch would be significant on the R. hippoglossoides fishing grounds (Kulka 2006). Based on distributional information, it is expected that most of the fish that would be captured in the fisheries in the NRA slope waters would be large juveniles or adults (Kulka 2006). Samples from the Russian R. hippoglossoides fleet in the NRA support this (Kulka 2006). Although incidental catch of this species in the NRA has not yet been quantified, recent population trends of adults have been stable (Kulka 2006).
Little information is available on threats in the southwest Atlantic Ocean.
This species is included in the total allowable catch (TACs) set for deepwater sharks by ICES in the Northeast Atlantic: In 2007, the TAC for deepwater sharks in sub-areas V, VI, VII, VIII and IX is 2,472 t. In 2008, the TAC for these species in these areas will be reduced to 1,646 t. In 2007 and 2008, the TAC for deepwater sharks is set at 20 t annually in Sub-area X, and 99 t in sub-area XII (ICES 2007).
Recommendations: Like many deeper water species, more information on biology, ecology and importance in fisheries are required to further assess future conservation needs.
|Citation:||Ebert, D.A., Crozier, P. & Blasdale, T. & McCormack, C. 2009. Centroscyllium fabricii. The IUCN Red List of Threatened Species 2009: e.T161521A5442458.Downloaded on 22 November 2017.|
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