Featured Elasmobranch – Bignose Shark
Category : Featured Elasmobranch
Photo Credit: John Carlson NOAA Fisheries, Copyrighted
Carcharhinus altimus (Springer 1950)
Family Carcharhinidae (Requiem Sharks)
Identification: A large, heavy-bodied cylindrical shark with a long, wide, and bluntly pointed snout, prominent nasal flaps, a distinguishingly prominent interdorsal ridge, pectoral and dorsal fins that are long and straight; the inner corners are blackish in coloration. Teeth in the upper jaw are broad, triangular, and serrated, and number 14-16 for each side, while in the lower jaw they are narrow, triangular, serrated, and number 14-15 for each side. Coloration is gray to bronze on the dorsal surface, with a white ventral area, and no conspicuous markings.
Size: The maximum size recorded of this shark is three meters total length, with a weight up to 168kg. Size at birth is 70-90 cm total length.
Distribution: Eastern Pacific records of this species are sparse, but it ranges from Baja California to Central America. Elsewhere, it has a patchy, yet circumglobal distribution in subtropical and tropical waters.
Habitat: The bignose shark can be found offshore in deeper waters from 90 m to at least 430 m on the outer continental shelves and upper slopes. Younger sharks are found at shallower depths, up to 25m, while the older sharks are found at the deeper depths. These sharks have been caught at the surface over deep outer continental shelf waters suggesting that they at least on occasion migrate far off the bottom.
Biology: Bignose sharks exhibit a viviparous reproductive mode, with each pup having a yolk sac from which they nourish during development. Litter size ranges from 3-15 pups. These sharks give birth to their pups at different time throughout the year based on their location. Male size at maturity is 215 cm, and size at maturity for females it is 225 cm. In the Mediterranean Sea, the females give birth from August to September but off Madagascar the females give birth in September and October! Virtually nothing is known about their biology in the eastern North Pacific. Bony fishes, such as mackerels, soles, and batfish, are food sources, as well as cephalopods. In addition, smaller elasmobranchs such as dogfishes, catsharks, stingrays are preyed upon.
General Interest: Bignose sharks generally occur in deep waters offshore, and as such they rarely come into contact with humans, and thus are not considered a danger. They have not been evaluated for the IUCN Red List, but may be of concern as they are taken as bycatch of deep pelagic longlines and bottom trawls. In US Waters, the bignose shark is prohibited from capture in the commercial fishing industry, but is caught elsewhere, particularly in the Caribbean, and used for fishmeal and oil.
By Jennifer Bigman
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039