Dusky Sharks, Carcharhinus obscurus
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Description & Behavior
Dusky sharks, Carcharhinus obscurus (Lesueur, 1818), reach 4.2 m in length and weigh a maximum of 346.5 kg. This large shark species has a broad, rounded snout, and triangular saw-edged upper teeth. Their curved pectoral fins are moderate in size, and they have an interdorsal ridge on their backs. The dusky is blue-gray to dark-gray on the dorsal side, white on the ventral side. They live to about 35 years.
World Range & Habitat
Dusky sharks are found in subtropical waters between 43°N-43°S in the western Atlantic from southern Massachusetts to Florida in the USA and in the Bahamas, Cuba, northern Gulf of Mexico, Nicaragua, and southern Brazil. In the eastern Atlantic, dusky sharks are found around the Canary Islands, Cape Verde, Senegal and Sierra Leone. They are also found in the Indo-West Pacific, Red Sea, Mozambique, South Africa, Japan, China, Vietnam and Australia. This is a highly migratory species generally found in coastal and offshore waters at depths between 200-400 m. Juveniles are often found in shallower waters.
Feeding Behavior (Ecology)
This species feeds on bony fish, sharks, skates, rays, cephalopods, gastropods, crustaceans, and occasionally on mammalian carrion, and even garbage.
Dusky sharks, Carcharhinus obscurus, are viviparous, meaning embryos are nourished by the female as it develops within her body. They bear small litters following a long gestation. Juveniles grow slowly and reach sexual maturity late in their life, which slows down the reproductivity of this species.
Conservation Status & Comments
Dusky sharks are not a dangerous species, however large adults may become aggressive if provoked. They are among the slowest-growing, latest-maturing of known sharks making them more vulnerable to overfishing than some other sharks. They are commonly caught as bycatch; the population in the northwestern Atlantic and Gulf of Mexico has been reduced to 15-20% of its mid-1970s level. This rate of decline will likely threaten this species beyond recovery.
References & Further Research
Research Carcharhinus obscurus » Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library [audio / video] ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS
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