{{Short description|Species of shark}} {{Speciesbox | name = Black dogfish | image = Centroscyllium fab.JPG | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Kulka, D.W. |author2=Anderson, B. |author3=Cotton, C.F. |author4=Herman, K. |author5=Pacoureau, N. |author6=Dulvy, N.K. |date=2020 |title=''Centroscyllium fabricii'' |volume=2020 |article-number=e.T161521A124499082 |doi=10.2305/IUCN.UK.2020-3.RLTS.T161521A124499082.en |access-date=19 November 2021}}</ref> | genus = Centroscyllium | species = fabricii | range_map = Centroscyllium fabricii distmap.png | range_map_caption = Range of the black dogfish | authority = (Reinhardt, 1825) | synonyms = ''Spinax fabricii'' <small>Reinhardt, 1825</small> }}
The '''black dogfish''' ('''''Centroscyllium fabricii''''') is a species of dogfish shark in the family Etmopteridae. It is common over the outer continental shelf and continental slope at depths of {{convert|180|-|2250|m|ft|abbr=on}}. Females generally inhabit deeper water than males, and depending on the region, smaller sharks may occur at different depths than larger ones. This species is distributed widely in the Atlantic Ocean, from Greenland and Iceland to Virginia and West Africa in the north, and off southwestern Africa and Argentina in the south. The largest member of its family, the black dogfish, typically measures {{convert|60|-|75|cm|in|abbr=on}} long. It has a stocky, dark brown body that is darker below than above, and bears scattered, minute bioluminescent organs. Its two dorsal fins are preceded by stout spines, and the anal fin is absent.
Active and schooling, the black dogfish is an opportunistic predator and scavenger that mainly consumes bony fishes, crustaceans, and cephalopods. It is aplacental viviparous, with females producing litters of four to 40 pups that are sustained to term by a yolk sac. There is no well-defined breeding season, and mating and birthing take place year-round. The black dogfish contributes significantly to the bycatch of deep-sea commercial fisheries operating in the North Atlantic; it is of little commercial value and is usually discarded. As large portions of its range see little deepwater fishing activity and its northwestern Atlantic population seems to be stable, the International Union for Conservation of Nature has listed this species under Least Concern overall. It has been assessed as Near Threatened in the northeastern Atlantic, where its numbers may have declined from heavy fishing pressure.
== Taxonomy and phylogeny == thumb|upright=1.2|left|Early illustration of a black dogfish The first known specimen of the black dogfish was collected near Julianehåb in Greenland and described by Danish zoologist Johannes Reinhardt in his 1825 ''Ichthyologiske bidrag''. Reinhardt gave it the name ''Spinax fabricii'' in honor of missionary and naturalist Otto Fabricius, who pioneered the study of Greenlandic fishes.<ref name="reinhardt"/> German biologists Johannes Müller and Jakob Henle, in their 1839–41 ''Systematische Beschreibung der Plagiostomen'', created the new genus ''Centroscyllium'' for this species.<ref name="muller and henle"/><ref name="evermann and jordan"/>
According to the IUCN, further taxonomic investigation is required to confirm the black dogfish in the North Atlantic and the southeastern Atlantic represent the same species.<ref name="iucn status 19 November 2021" /> A 2010 phylogenetic study by Nicolas Straube and colleagues, based on nuclear and mitochondrial DNA, found the black dogfish is the sister species of the whitefin dogfish (''C. ritteri''), and the two are, in turn, sister to the clade formed by the granular dogfish (''C. granulatum'') and combtooth dogfish (''C. nigrum'').<ref name="straube et al"/>
== Distribution and habitat == The black dogfish is a common species, with a wide but discontinuous distribution in the temperate waters of the Atlantic Ocean; its range abuts, but does not extend into, the Arctic Ocean. In the northeast, it occurs from Iceland to Sierra Leone, including the Faroe Islands, southern Norway, and the Rockall Trough and Porcupine Seabight off Ireland. In the northwest, it is found from southern Greenland and Baffin Island to Virginia, being particularly abundant in the Laurentian Channel, and may occur further south to the Gulf of Mexico off Alabama. In the southeast, it is found off Namibia and South Africa as far as Cape Agulhas.<ref name="iucn status 19 November 2021" /><ref name="compagno"/> In the southwest, it has been recorded from the Beagle Channel at the southern tip of Argentina.<ref name="menni et al"/>
Inhabiting the outer continental shelf and continental slope, the black dogfish is found mostly near the bottom in water {{convert|180|-|2250|m|ft|abbr=on}} deep.<ref name="compagno"/> It is most common at depths of {{convert|800|-|1200|m|ft|abbr=on}} off Iceland, {{convert|1250|-|1500|m|ft|abbr=on}} in the Rockall Trough, {{convert|500|-|1300|m|ft|abbr=on}} off Greenland, {{convert|350|-|500|m|ft|abbr=on}} off northern Canada, and below {{convert|500|m|ft|abbr=on}} off southern Africa.<ref name="iucn status 19 November 2021" /><ref name="jakobsdottir"/> The species may venture closer to the surface in the northern extreme of its range, particularly during the dark, cold winter months.<ref name="compagno"/> Depth segregation by sex has been documented in the North Atlantic, with females outnumbering males at depths greater than {{convert|1|km|mi|abbr=on}}. Depth segregation by size varies by region: larger sharks are generally found in deeper water off western Greenland, in shallower water off western Iceland, and without pattern with respect to depth off eastern Iceland.<ref name="jakobsdottir"/> The black dogfish prefers water temperatures of {{convert|3.5|-|4.5|C|F}}, though off northern Canada, it is most abundant in water of {{convert|5|-|6.5|C|F}}; it can tolerate temperatures down to {{convert|1|C|F}}.<ref name="iucn status 19 November 2021" /> There is some evidence that this species conducts seasonal migrations, spending winter and spring in shallower water.<ref name="compagno"/> Sharks off northern Canada perform development-related movements (see below) not observed off western Greenland, suggesting the presence of two distinct stocks in the northwestern Atlantic.<ref name="iucn status 19 November 2021" />
== Description == thumb|upright=1.2|The black dogfish has a stout, dark brown body and large green eyes; this specimen has light patches where its dermal denticles have rubbed off from handling. Adult black dogfish typically measure {{convert|60|-|75|cm|in|abbr=on}} in length and can reach {{convert|1.1|m|ft|abbr=on}}, making it the largest member of its family.<ref name="straube et al"/><ref name="burgess and bester"/> Females attain a larger ultimate size than males.<ref name="jakobsdottir"/> The shark has a rather stocky and laterally compressed body, with a moderately long, thick, and flattened snout that forms a very broad arch at the front. The sizable, horizontally oval eyes are a reflective green in life and lack nictitating membranes (protective third eyelids); they are followed a short distance behind by much smaller spiracles (accessory respiratory openings). The nostrils are anteriorly placed and preceded by short flaps of skin. The mouth is wide and evenly arched, with thin lips and short but deep furrows around the corners. There are around 34 tooth rows in either side of both jaws; each tooth has three (occasionally up to five) slender cusps, with the central one the longest.<ref name="compagno"/><ref name="burgess and bester"/><ref name="bigelow and schroeder"/>
Both dorsal fins are immediately preceded by stout, grooved spines, with the second much longer than the first. The small first dorsal fin has a rounded apex and a nearly straight trailing margin, with its origin lying behind the pectoral fins. The second dorsal fin is rather angular and has about double the area of the first, with its origin located opposite the midpoint of the pelvic fin bases. The pectoral fins are small and rounded. The pelvic fins are about as large as the second dorsal fin, with rounded tips and nearly straight trailing margins. The caudal peduncle is short and leads to a broad caudal fin comprising less than a quarter of the total length; the upper lobe has a convex upper margin leading to a squared-off tip, while the lower lobe is indistinct. The skin is densely covered by tiny dermal denticles; each one is recurved and thornlike, rising from an irregular star-shaped base. This species is a plain dark brown above, darkening to almost black below, with white dorsal fin spines. Juvenile sharks have white edges on the dorsal, pectoral, and pelvic fins. Minute, luminescent dots are scattered about the skin without a regular pattern.<ref name="compagno"/><ref name="burgess and bester"/><ref name="bigelow and schroeder"/>
== Biology and ecology == The black dogfish forms shoals or schools that tend to be larger during the winter and spring.<ref name="compagno"/><ref name="uiblein et al"/> Though fairly active,<ref name="sedberry and musick"/> its swimming muscles exhibit lower activity of glycolytic enzymes and higher activity of creatine phosphokinase compared to the shallow-water spiny dogfish (''Squalus acanthias''), suggesting a lesser capacity for bursts of speed.<ref name="treberg et al"/> The lipid-filled liver comprises about one-fifth of its total weight and functions in maintaining neutral buoyancy.<ref name="jakobsdottir"/> Potential predators of the black dogfish are larger sharks and bony fishes.<ref name="burgess and bester"/> It is one of several deep-sea sharks parasitized by the barnacle ''Anelasma squalicola'', which attaches in front of the second dorsal fin and impairs the reproductive development of its host.<ref name="yano and musick"/> Other known parasites of this species include the fluke ''Otodistomum cestoides'',<ref name="gibson"/> the copepods ''Neoalbionella fabricii'' and ''Neoalbionella centroscyllii'',<ref name="rubec and hogans"/><ref name="rodriguez et al"/> and the protozoans ''Haemogregarina delagei'' and ''Trypanosoma rajae''.<ref name="mcdonald and margolis"/>
thumb|upright=1.2|Rattails are among the prey consumed by the black dogfish. Apparently opportunistic in feeding habits, the black dogfish typically hunts in open water, but also scavenges off the bottom.<ref name="sedberry and musick"/><ref name="mauchline and gordon"/> The bulk of its diet consists of a variety of bony fishes, including rattails, whitings, rockfishes, lanternfishes, and barracudinas, as well as pelagic crustaceans such as krill and shrimp, and cephalopods. Fish become a progressively more important food source as the shark ages, while crustaceans become less important. Infrequently, polychaete worms and jellyfish are also eaten.<ref name="jakobsdottir"/><ref name="mauchline and gordon"/> In the northwestern Atlantic, Greenland halibut (''Reinhardtius hippoglossoides'') and rattail offal discarded from fishing vessels have become a major source of food for this species, particularly for older sharks that are capable of consuming larger pieces such as heads.<ref name="punzon and herrera"/>
=== Life history === Reproduction in the black dogfish occurs year-round, with no well-defined seasonal pattern.<ref name="jakobsdottir"/><ref name="yano"/> This species is aplacental viviparous, in which the developing embryos are retained inside the uterus and are sustained to term solely by yolk. Mature females have two functional ovaries and two functional uteruses. Fertilized eggs are ovulated into the uterus at a diameter of {{convert|3.0|-|4.5|cm|in|abbr=on}}, though a few may be retained in the ovary; the eggs are not enclosed in a capsule. The external yolk sac is fully resorbed when the embryo is close to term, with the remaining yolk having been transferred to an internal yolk sac attached to the intestine. The internal yolk sac serves to provision the newborn shark until it learns to feed. The litter size ranges from four to 40.<ref name="yano"/> Newborns measure {{convert|13|-|19|cm|in|abbr=on}} long.<ref name="yano"/><ref name="haedrich"/>
Various authors have reported the size at maturity as between {{convert|46|and|63|cm|in|abbr=on}} for males and {{convert|51|and|70|cm|in|abbr=on}} for females, reflecting differences between geographical areas.<ref name="iucn status 19 November 2021" /> Off northern Canada, females give birth in the portion of the Laurentian Channel less than {{convert|400|m|ft|abbr=on}} deep. As the young grow, they migrate into the deeper parts of the Channel, and eventually a long distance northward over the Grand Banks or the Labrador Shelf, to the deep continental slope. This movement pattern has not been observed in black dogfish inhabiting adjacent waters off western Greenland.<ref name="iucn status 19 November 2021" /> A number of anomalous hermaphroditic specimens have been documented.<ref name="yano"/>
== Human interactions == The black dogfish is harmless to humans and of little commercial value. Substantial numbers are caught incidentally by commercial deep-sea trawl, gillnet, and longline fisheries operating throughout the North Atlantic, including the Icelandic Greenland halibut fishery, the French mixed-species trawl fishery, and the Canadian Greenland halibut, crab, redfish, monkfish, and witch fisheries. Captured sharks are usually discarded, though in recent years this and other small deepwater sharks have been increasingly retained and used for fishmeal.<ref name="iucn status 19 November 2021" /><ref name="burgess and bester"/> Reported catches by European countries, of which France made the largest contribution, have followed a declining trend from 486 tons in 2001 to 35 tons in 2006.<ref name="ices"/> The average catch by Canadian fisheries was 68 tons per year from 1996 to 2005. The black dogfish occurs mostly too deep for fisheries off southern Africa; in the remainder of its range, little information is available on fishery impact.<ref name="iucn status 19 November 2021" />
The International Union for Conservation of Nature (IUCN) has listed the black dogfish under Least Concern worldwide; it is minimally affected by fishing activity across many parts of its range, while its population in the northwestern Atlantic presently seems to be stable and may have increased from 1978 to 1995.<ref name="iucn status 19 November 2021" /><ref name="baker et al"/> By contrast, the intensity of deepwater fisheries in the northeastern Atlantic has led the IUCN to give this species a regional assessment of Near Threatened. The reproductive characteristics of the black dogfish, such as a large female maturation size, may render it susceptible to overfishing, though it is more fecund than other deep-sea dogfish sharks. In the northeastern Atlantic, catches of this species are managed as part of the total allowable catch for deep-sea sharks set by the International Council for the Exploration of the Sea (ICES).<ref name="iucn status 19 November 2021" />
== References == {{Reflist|colwidth=30em|refs= <ref name="baker et al">{{cite journal |author=Baker, K.D. |author2=J.A. Devine |author3=R.L. Haedrich |name-list-style=amp |title=Deep-sea fishes in Canada's Atlantic: population declines and predicted recovery times |journal=Environmental Biology of Fishes |volume=85 |issue=1 |pages=79–88 |doi=10.1007/s10641-009-9465-8 |year=2009|bibcode=2009EnvBF..85...79B |s2cid=44245140 }}</ref>
<ref name="bigelow and schroeder">{{cite book |title=Fishes of the Western North Atlantic, Part 1 |author1=Bigelow, H.B. |author2=Schroeder, W.C. |name-list-style=amp |publisher=Sears Foundation for Marine Research, Yale University |year=1953 |pages=480–486}}</ref>
<ref name="burgess and bester">Burgess, G. and Bester, C. [http://www.flmnh.ufl.edu/fish/Gallery/Descript/BlackDogfish/BlackDogfish.html Biological Profiles: Black Dogfish]. Florida Museum of Natural History Ichthyology Department. Retrieved on October 2, 2010.</ref>
<ref name="compagno">{{cite book |author=Compagno, L.J.V. |year=1984 |title=Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date |publisher=Food and Agricultural Organization |isbn=92-5-101384-5 |pages=46–48}}</ref>
<ref name="evermann and jordan">{{cite book |title=The Fishes of North and Middle America: A Descriptive Catalogue of the Species of Fish-like Vertebrates Found in the Waters of North America, North of the Isthmus of Panama |volume=1 |author1=Evermann, B.W. |author2=Jordan, D.S. |name-list-style=amp |publisher=Government Printing Office |year=1896 |page=56}}</ref>
<ref name="gibson">{{cite book |title=Guide to the Parasites of Fishes of Canada, Volume 4 |author=Gibson, D.I. |publisher=NRC Research Press |year=1996 |isbn=0-660-16403-5 |page=74}}</ref>
<ref name="haedrich">{{cite book |author=Haedrich, R.L. |year=1995 |chapter=Structure over time of an exploited deepwater fish assemblage |title=Deep-water Fisheries of the North Atlantic Oceanic Slope |pages=70–96 |editor=Hopper, A.G. |publisher=Kluwer Academic Publishers |isbn=0-7923-3511-2}}</ref>
<ref name="ices">ICES (International Council for the Exploration of the Sea). (2007). [http://www.ices.dk/reports/ACOM/2007/WGEF/WGEF07.pdf Report of the Working Group Elasmobranch Fishes (WGEF), 22–28 June 2007, Galway, Ireland] {{webarchive|url=https://web.archive.org/web/20110612100812/http://www.ices.dk/reports/ACOM/2007/WGEF/WGEF07.pdf |date=12 June 2011 }}. ICES CM 2007/ACFM:27.</ref>
<ref name="jakobsdottir">{{cite journal |author=Jakobsdóttir, K.B. |title=Biological aspects of two deep-water squalid sharks: ''Centroscyllium fabricii'' (Reinhardt, 1825) and ''Etmopterus princeps'' (Collett, 1904) in Icelandic waters |journal=Fisheries Research |volume=51 |issue=2–3 |date=May 2001 |pages=247–265 |doi=10.1016/S0165-7836(01)00250-8|bibcode=2001FishR..51..247J }}</ref>
<ref name="mauchline and gordon">{{cite journal |author1=Mauchline, J. |author2=J.D.M. Gordon |name-list-style=amp |title=Diets of the sharks and chimaeroids of the Rockall Trough, northeastern Atlantic Ocean |journal=Marine Biology |volume=75 |issue=2–3 |pages=269–278 |doi=10.1007/BF00406012 |year=1983|bibcode=1983MarBi..75..269M |s2cid=84676692 }}</ref>
<ref name="mcdonald and margolis">{{cite book |title=Synopsis of the parasites of fishes of Canada: Supplement (1978–1993) |author1=McDonald, T.E. |author2=L. Margolis |name-list-style=amp |publisher=NRC Research Press |year=1995 |isbn=0-660-15902-3 |pages=9, 19}}</ref>
<ref name="menni et al">{{cite journal |title=Occurrence of ''Centroscyllium fabricii'' (Reinhardt, 1825)(Elasmobranchii, Squalidae) in the Beagle Channel, southern south America |author1=Menni, R.C. |author2=G.H. Burgess |author3=M.L. Garcia |name-list-style=amp |journal=Bulletin of Marine Science |year=1993 |volume=52 |issue=2 |pages=824–832 |url=http://cat.inist.fr/?aModele=afficheN&cpsidt=4770442}}</ref>
<ref name="muller and henle">{{cite book |author1=Müller, J. |author2=Henle, F.G.J. |name-list-style=amp |year=1839 |title=Systematische Beschreibung der Plagiostomen |volume=2 |publisher=Veit und Comp. |location=Berlin |page=191 |url=https://www.biodiversitylibrary.org/page/6353102 |language=German}}</ref>
<ref name="punzon and herrera">{{cite journal |author1=Punzón, A. |author2=M.A. Herrera |name-list-style=amp |title=Feeding of ''Centroscyllium fabricii'' and the influence of discards on its diet in Flemish Pass (north-west Atlantic) |journal=Journal of the Marine Biological Association of the UK |year=2000 |volume=80 |issue=4 |pages=755–756 |doi=10.1017/S002531540000268X|bibcode=2000JMBUK..80..755P |s2cid=84800991 }}</ref>
<ref name="reinhardt">{{cite book |author=Reinhardt, J.C.H. |year=1825 |chapter=Ichthyologiske bidrag |editor=Örsted, H.C. |title=Oversigt over det Kongelige Danske Videnskabernes Selskabs Forhandlinger og dets Medlemmers Arbeider (Kjøbenhavn) |pages=1–35 |language=Danish}}</ref>
<ref name="rodriguez et al">{{cite journal |author=Rodríguez, S.M. |author2=J.L. Luque |author3=M. George-Nascimento |name-list-style=amp |title=A parasitic copepod, ''Neoalbionella'' sp. (Lernaeopodidae), on the southern lanternshark ''Etmopterus granulosus'' (Etmopteridae) off Juan Fernández Archipelago, Chile |journal=Revista de Biología Marina y Oceanografía |volume=45 |issue=2 |pages=359–363 |year=2010 |doi=10.4067/S0718-19572010000200020|doi-access=free }}</ref>
<ref name="rubec and hogans">{{cite journal |author1=Rubec, L.A. |author2=W.E. Hogans |name-list-style=amp |year=1988 |title=''Albionella fabricii'' n. sp. (Copepoda: Lernaeopodidae) from the gills of ''Centroscyllium fabricii'' from the Northwest Atlantic |journal=Systematic Parasitology |volume=11 |issue=3 |pages=219–225 |doi=10.1007/BF00010002|s2cid=32969107 }}</ref>
<ref name="sedberry and musick">{{cite journal |author1=Sedberry, G.R. |author2=J.A. Musick |name-list-style=amp |title=Feeding strategies of some demersal fishes of the continental slope and rise off the Mid-Atlantic Coast of the USA |journal=Marine Biology |volume=44 |issue=4 |pages=357–375 |doi=10.1007/BF00390900 |year=1978|bibcode=1978MarBi..44..357S |s2cid=83608467 }}</ref>
<ref name="straube et al">{{cite journal |author1=Straube, N. |author2=S.P. Iglésias |author3=D.Y. Sellos |author4=J. Kriwet |author5=U.K. Schliewen |name-list-style=amp |title=Molecular phylogeny and node time estimation of bioluminescent Lantern Sharks (Elasmobranchii: Etmopteridae) |journal=Molecular Phylogenetics and Evolution |volume=56 |issue=3 |pages=905–917 |date=September 2010 |doi=10.1016/j.ympev.2010.04.042 |pmid=20457263|bibcode=2010MolPE..56..905S }}</ref>
<ref name="treberg et al">{{cite journal |author=Treberg, J.R. |author2=R.A. Martin |author3=W.R. Driedzic |name-list-style=amp |year=2003 |title=Muscle enzyme activities in a deep-sea squaloid shark, ''Centroscyllium fabricii'', compared with its shallow-living relative, ''Squalus acanthias'' |journal=Journal of Experimental Zoology Part A: Comparative Experimental Biology |volume=300A |pages=133–139 |doi=10.1002/jez.a.10318 |issue=2|pmid=14648673 |bibcode=2003JEZ...300..133T }}</ref>
<ref name="uiblein et al">{{cite book |author=Uiblein, F. |author2=M. Youngbluth |author3=C. Jacoby |author4=F. Pages|author5=M. Picheral |author6=G. Gorsky |name-list-style=amp |chapter=In situ observations of deepwater fishes in four canyons off the Georges Bank, NW Atlantic |title=Deep Sea 2003: Conference on the Governance and Management of Deep-sea Fisheries, Queenstown (New Zealand), 1–5 Dec 2003 |year=2005 |publisher=Food and Agricultural Organization of the United Nations |isbn=92-5-105402-9 |pages=98–106}}</ref>
<ref name="yano">{{cite journal |author=Yano, K. |title=Reproductive Biology of the Black Dogfish, ''Centroscyllium Fabricii'', Collected From Waters off Western Greenland |journal=Journal of the Marine Biological Association of the United Kingdom |year=1995 |volume=75 |pages=285–310 |doi=10.1017/S002531540001818X |issue=2|bibcode=1995JMBUK..75..285Y |s2cid=86173063 }}</ref>
<ref name="yano and musick">{{cite journal |author1=Yano, K. |author2=J.A. Musick |name-list-style=amp |title=The Effect of the mesoparasitic barnacle ''Anelasma'' on the development of reproductive organs of deep-sea squaloid sharks, ''Centroscyllium'' and ''Etmopterus'' |journal=Environmental Biology of Fishes |volume=59 |issue=3 |pages=329–339 |doi=10.1023/A:1007649227422 |year=2000|bibcode=2000EnvBF..59..329Y |s2cid=6049145 }}</ref>
}}
== External links == {{Commons category|Centroscyllium fabricii|Black dogfish}} * [http://fishbase.org/Summary/speciesSummary.php?ID=656&genusname=Centroscyllium&speciesname=fabricii&lang=English ''Centroscyllium fabricii'', Black dogfish] at [http://www.fishbase.org/search.php FishBase] * [http://www.flmnh.ufl.edu/fish/Gallery/Descript/BlackDogfish/BlackDogfish.html Biological Profiles: Black Dogfish] {{Webarchive|url=https://web.archive.org/web/20130602055612/http://www.flmnh.ufl.edu/fish/Gallery/Descript/BlackDogfish/BlackDogfish.html |date=2013-06-02 }} at [http://www.flmnh.ufl.edu/fish/ Florida Museum of Natural History Ichthyology Department]
{{Squaliformes}} {{Taxonbar|from=Q2380356}} {{Good article}}
{{DEFAULTSORT:Black dogfish}} Category:Centroscyllium Category:Fish of the Atlantic Ocean Category:Fish described in 1825 Category:Taxa named by Johan Reinhardt