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BRONZE WHALER SHARK
Order - Carcharhiniformes
Family - Carcharhinidae
Genus - Carcharhinus
Species - brachyurus
Narrowtooth Shark

Taxonomy

GŁnther first described Carcharhinus brachyurus in 1870. Synonyms include Carcharias lamiella Jordan and Gilbert 1882, Eulamia ahenea Stead 1938, Carcharhinus improvisus Smith 1952, Carcharhinus rochensis Abella 1972, Carcharhinus remotoides Deng, Xiong and Zhan 1981, and Carcharhinus acarenatus Morenos and Hoyos 1983. The genus name Carcharhinus is derived from the Greek "karcharos" meaning sharpen and "rhinos" meaning nose; the species name brachyurus means "short-bodied".


Common Names

English language common names for this species include narrowtooth shark, bronze, bronze whaler, bronze whaler shark, bronzie, cocktail shark, cocktail whaler, narrow-tooth shark, copper shark. The common name of copper shark is in reference to the coppery body color while the common name bronze whaler refers to the alleged habit of feeding on whale carcasses in Australian waters. Other common names include karcharinos vrachyouros (Greek), bacota, cazón, jaqueta, jaquetón, tiburón cobrizo and tollo mantequero (Spanish), bronzie and koperhaai (Afrikaans), cŠ m‚p duŰi ngan (Vietnamese), cac„o and tubar„o-cobre (Portuguese), horopekapeka, ngerungeru and toiki (Maori), kobberhaj (Danish), koperhaai (Dutch), kopparhai (Swedish), kupferhai (German), kuroherimejiro (Japanese), requin and requin cuivre (French), squalo ramato (Italian) and zarlacz miedziany (Polish).


Geographical Distribution

The bronze whaler shark has a world wide distribution in warm temperate and subtropical waters. Locally, it can be found from North Carolina to Brazil and throughout the Gulf of Mexico.


map
World distribution map for the bronze whaler shark


Habitat

The bronze whaler shark commonly occupies a variety of habitats from freshwater and brackish areas of large rivers to shallow bays and estuaries. It has been found from the surf line to depths of up to 328 feet (100 m), but is believed to range deeper.


Biology
Bronze whaler sharks
© Doug Perrine
∑ Distinctive Features
The bronze whaler shark is stocky with a slight arch to the body above the gill slits. It has a lean and pointed snout and characteristic narrowly triangular teeth. The eyes of this shark are circular and relatively large. Bronze whaler sharks have moderately large pectoral fins with narrowly rounded or pointed tips. The caudal fin has a bulge near the base of the front edge. This species lacks an interdorsal ridge.

Although this shark may be easily confused with C. obscurus, C. limbatus, C. plumbeus, and C. brevipinna, it can be distinguished by its distinctive upper teeth as well as the lack of any pronounced body markings and little to no dorsal ridge.


∑ Coloration
The bronze whaler shark is bronzy grey to olive-grey in color on its dorsal surface and white on the ventral surface. This counter shading serves to camouflage the animal from predators or prey below. This species has dark markings on the edge of its fins and white or dusky tips. Bronze whaler sharks are often confused with blacktip sharks or spinner sharks because of their markings.


Bronze whaler shark jaw
© Florida Program for Shark Research
∑Dentition
Juvenile bronze whaler sharks have teeth in the upper jaw that are finely serrated and have erect symmetrical cusps. Adult bronze whaler sharks on the other hand, have narrowly triangular finely serrated cusps in the center of the upper jaw, which become more oblique as they move out towards the corners of the mouth. The lower teeth are characterized by more oblique cusps and are finely serrated as well. Tooth counts range from 14 to 16 on either side of the upper jaw and 14 - 15 on either side if the lower jaw.


∑Denticles
The bronze whaler shark has placoid scales, commonly referred to as denticles, which are tooth-like in structure and very firmly embedded in the skin.


∑Size, Age, and Growth
Bronze whaler sharks average about 24 inches (61.0 cm) total length (TL) at birth. They commonly reach maturity at 81-93 inches (205.7-236.2 cm) TL and 89-96 inches (226.1-243.8 cm) TL for males and females respectively. The maximum size for a bronze whaler shark is reported to be 115 inches (292.1 cm) TL. The age at maturity is 13 years old for males, and 20 years old for females and the maximum age is unknown.


Bronze whaler sharks feeding on sardines off the coast of South Africa
© Doug Perrine
∑ Food Habits
The diet of the bronze whaler shark consists of a variety of cephalopods including squid and octopus as well as fishes such as sardines, mullet, and flatfish. During the winter months, large numbers of bronze whaler sharks follow the sardine shoals along the coast of southern Natal. Adult bronze whaler sharks are also known to feed on other elasmobranchs such as stingrays and sawfish.


∑ Reproduction
The bronze whaler shark has a viviparous mode of reproduction, which means that embryos develop inside the uteri of the mother and are born live. It is believed that reproduction in bronze whaler sharks occurs biennially. According to the limited data that is available on the biology of this species parturition in South Africa most likely occurs in June or July and litters range from 13 to 24 pups with an average of 15. Other studies have combined data from several locations and suggest varying paturation times from June to February. Gestation is estimated to last 12 months with the young approximately 23.2-27.6 inches (59-70 cm) TL at birth. The bronze whaler shark utilizes inshore bays and coasts as nursery areas.


∑ Predators
Some predators of the bronze whaler shark may include larger sharks and humans.


∑ Parasites
Otodistomum veliporum is a type of fluke that has been found in the stomach and spiral valve of bronze whaler sharks in Brazil. Cathetocephalus australis is a tapeworm that can also be found in bronze whaler sharks from the southwestern Atlantic Ocean.


Importance to Humans

The bronze whaler shark is commercially important in places like New Zealand, South Africa and Brazil. Although little has been recorded concerning landings of the bronze whaler shark, it is thought to be used for human consumption where it occurs. It is commonly taken in bottom trawls, by line gear and by sports fishermen.


Danger to Humans

The bronze whaler shark has been implicated in some attacks on swimmers. It is considered dangerous to humans but much less than a tiger shark (Galeocerdo cuvier) or bull shark (C. leucas). The International Shark Attack File has recorded 30 attacks linked to the narrowtooth shark since 1962, however none of these attacks resulted in a fatality.


Conservation

The bronze whaler shark was listed as "Near Threatened" on the IUCN Red List in 2003. This listing is based on the fact that this species does not seem to be naturally abundant anywhere. It appears to have small regional populations with little movement of individuals between populations.


Prepared by:
Michelle Press