Bignose shark
A deepwater requiem shark with a circumglobal tropical distribution.
The bignose shark (Carcharhinus altimus) is a deep-water requiem shark found around the world in warm seas. It migrates and lives near the edge of the continental shelf, usually between 90 and 430 meters down, though it may rise closer to the surface or into shallower water at night. This shark is plain in color and reaches at least 2.7 to 2.8 meters in length. It has a long, wide snout with prominent skin flaps around its nostrils, tall triangular upper teeth, long almost-straight pectoral fins, and a ridge running along its back between the two dorsal fins.
Hunting near the seafloor, it eats bony fish, cartilaginous fish, and cephalopods. The species is viviparous: females nourish their embryos through a placental connection and give birth to litters of three to 15 pups after a 10-month gestation. Because it lives so deep, it poses little danger to humans. It is caught incidentally by fisheries across its range, and its meat, fins, skin, liver oil, and offal are used. Given its slow reproduction, fishing pressure is a concern, and numbers may have already dropped in the northwestern Atlantic and elsewhere.
The shark was first described by Stewart Springer in 1950 as *Eulamia altima*, but later placed in the genus *Carcharhinus*. The name *altimus* comes from the Latin for "deep," referring to its habitat. The type specimen—an immature female 1.3 meters long—was caught off Cosgrove Reef in the Florida Keys on April 2, 1947. An older common name, Knopp's shark, was used by Florida fishery workers before the species was formally described.
Based on morphology, studies in 1982 and 1988 grouped the bignose shark with the dusky shark and Galapagos shark in the "obscurus group," which includes large, triangular-toothed sharks with a dorsal ridge. A 1992 allozyme study confirmed this "ridge-backed" group and found the bignose shark to be the sister species of the sandbar shark.
Records are patchy, but the bignose shark appears to live worldwide in tropical and subtropical waters. In the Atlantic, it ranges from Delaware Bay to Brazil, the Mediterranean, and off West Africa. In the Indian Ocean, it is known off South Africa, Madagascar, the Red Sea, India, and the Maldives. In the Pacific, it has been recorded from China to Australia, around Hawaii, and from the Gulf of California to Ecuador.
Quick Facts
- Genus
- Carcharhinus
- Species
- altimus
Facts from the source article.
Lore & Background
Shark expert Stewart Springer described the bignose shark as Eulamia altima in a 1950 issue of the journal American Museum Novitates. The specific epithet altimus is derived from the Latin altus ('deep'), referring to its deepwater habits. The type specimen is an immature female 1.3 m long, caught off Cosgrove Reef in the Florida Keys on April 2, 1947. An alternate common name is Knopp's shark, used by Florida fishery workers before the species was described. Phylogenetic studies have placed it in the 'obscurus group' of Carcharhinus, with the bignose shark found to be the sister species of the sandbar shark (C. plumbeus).
The bignose shark is found near the edge of the continental shelf and over the upper continental slope, generally swimming close to the sea floor. Young sharks may venture into water as shallow as 25 m. Night-time captures from close to the surface suggest it may perform a diel vertical migration. In the northwestern Atlantic, it conducts a poorly documented seasonal migration, with individual sharks recorded traveling distances between 1,600 and 3,200 km. The shark is rather heavily built, with a long, broad, and blunt snout, and a high midline ridge between the dorsal fins. Its coloration is gray to bronze above with a faint pale stripe on the flank, and white below.
Reader's Guide
The bignose shark is caught incidentally by commercial fisheries in many parts of its range, including gillnet, bottom trawl, and deep-set pelagic longline fisheries. Its meat, fins, skin, liver oil, and offal may be used. In Cuban waters it is regularly taken for liver oil, shagreen, and fishmeal; elsewhere, such as in Southeast Asia, the meat is consumed and the fins shipped to East Asia for shark fin soup. It is not used commercially in the United States, where it is listed as a Prohibited Species under the 2007 Fishery Management Plan for Atlantic tunas, swordfish and sharks, or in Australia. The International Union for Conservation of Nature has listed the bignose shark as near threatened overall. The species is considered of concern given its slow reproductive rate and widespread heavy fishing pressure. There is evidence of recent decline in the Maldives, and it may have already declined in the northwestern Atlantic, where it is commonly misidentified as the sandbar shark. It is listed as a 'highly migratory species' under the 1995 UN Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks, but this has not led to significant conservation measures. In Australian waters it is assessed as Least Concern, facing no significant threats.
Did You Know?
- The bignose shark was originally described as Eulamia altima by Stewart Springer in 1950.
- The bignose shark is commonly misidentified as the sandbar shark in the northwestern Atlantic.
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