black black species shark family common outer continental shelf continental slope depths females generally inhabit deeper water males depending region smaller sharks occur different depths larger ones species distributed widely atlantic_ocean greenland iceland virginia west_africa north southwestern africa argentina south largest member family black typically measures long dark brown body darker bears scattered minute organs dorsal fins preceded stout spines anal fin absent active schooling black predator mainly bony fishes crustaceans cephalopods viviparous females producing litters pups sustained term yolk sac defined breeding season mating place year round black contributes significantly deep sea commercial fisheries operating north_atlantic little commercial value usually discarded large portions range little fishing activity northwestern atlantic population stable listed species concern overall assessed northeastern atlantic numbers declined heavy fishing pressure taxonomy phylogeny known specimen black collected near greenland described danish zoologist gave honor missionary naturalist pioneered study fishes german der created new genus species according iucn taxonomic investigation required confirm black north_atlantic southeastern atlantic represent species phylogenetic study colleagues based nuclear mitochondrial dna found black sister species turn sister clade formed distribution habitat black common species wide distribution temperate waters atlantic_ocean range extend northeast occurs iceland sierra including southern norway ireland northwest found southern greenland virginia particularly abundant occur south gulf_of_mexico alabama southeast found south_africa far southwest recorded southern tip argentina inhabiting outer continental shelf continental slope black found near water deep common depths iceland trough greenland northern canada southern africa species venture closer surface northern extreme range particularly dark cold winter months depth segregation sex documented north_atlantic females males depths greater depth segregation size varies region larger sharks generally found deeper water western greenland shallower water western iceland pattern respect depth eastern iceland black prefers water temperatures northern canada abundant water tolerate temperatures evidence species conducts seasonal spending winter spring shallower water sharks northern canada perform development related movements observed western greenland suggesting presence distinct stocks northwestern atlantic description adult black typically measure length reach making largest member family females attain larger ultimate size males shark compressed body moderately long thick flattened snout forms broad arch sizable horizontally oval eyes reflective green life lack membranes protective followed short distance smaller openings nostrils placed preceded short flaps skin mouth wide evenly arched thin lips short deep furrows corners tooth rows jaws tooth occasionally slender central longest dorsal fins immediately preceded stout spines second longer small dorsal fin rounded apex nearly straight trailing margin origin lying pectoral fins second dorsal fin angular double area origin located opposite pelvic fin bases pectoral fins small rounded pelvic fins large second dorsal fin rounded tips nearly straight trailing margins caudal short leads broad caudal fin comprising quarter total length upper lobe convex upper margin leading squared tip lower lobe indistinct skin densely covered tiny dermal denticles like rising irregular star shaped base species plain dark brown black white dorsal fin spines juvenile sharks white edges dorsal pectoral pelvic fins minute dots scattered skin regular pattern biology ecology black forms schools tend larger winter spring fairly active swimming muscles exhibit lower activity higher activity compared shallow water suggesting lesser capacity bursts speed filled liver comprises fifth total weight functions maintaining neutral potential predators black larger sharks bony fishes deep sea sharks second dorsal fin reproductive development host known parasites species include apparently feeding habits black typically hunts open water bulk diet consists variety bony fishes including crustaceans shrimp cephalopods fish progressively important food source shark ages crustaceans important worms eaten northwestern atlantic greenland discarded fishing vessels major source food species particularly older sharks capable consuming larger pieces heads life history reproduction black occurs year round defined seasonal pattern species viviparous developing embryos retained inside sustained term solely yolk mature females functional functional eggs diameter retained eggs enclosed capsule external yolk sac fully embryo close term remaining yolk having transferred internal yolk sac attached internal yolk sac serves provision newborn shark learns feed litter size ranges measure long authors reported size maturity males females reflecting differences geographical areas northern canada females birth portion deep young grow migrate deeper parts channel eventually long distance northward deep continental slope movement pattern observed black inhabiting adjacent waters western greenland number specimens documented human interactions black harmless humans little commercial value substantial numbers caught incidentally commercial deep sea fisheries operating north_atlantic including greenland fishery french mixed species fishery canadian greenland crab witch fisheries captured sharks usually discarded recent years small sharks increasingly retained reported catches european countries france largest contribution followed declining trend tons tons average catch canadian fisheries tons year black occurs deep fisheries southern africa remainder range little information available fishery impact listed black concern worldwide affected fishing activity parts range population northwestern atlantic presently stable increased contrast intensity fisheries northeastern atlantic led iucn species regional assessment reproductive characteristics black large female maturation size render susceptible deep sea sharks northeastern atlantic catches species managed total catch deep sea sharks set
Black dogfish