bronze whaler

The copper shark (''Carcharhinus brachyurus''), bronze whaler, or narrowtooth shark, is a species of requiem shark, family Carcharhinidae, and the only member of its genus found mostly at temperate latitudes. It is distributed in a number of separate populations in the northeastern and southwestern Atlantic, off southern Africa, in the northwestern and eastern Pacific, and around Australia and New Zealand, with scattered reports from equatorial regions. This species can be found from brackish rivers and estuaries, to shallow bays and harbors, to offshore waters deep or more. Females are found apart from males for most of the year, and conduct seasonal migrations. A large species reaching long, the copper shark is difficult to distinguish from other large requiem sharks. It is characterized by its narrow, hook-shaped upper teeth, lack of a prominent ridge between the dorsal fins, and plain bronze coloration.

Feeding mainly on cephalopods, bony fishes, and other cartilaginous fishes, the copper shark is a fast-swimming predator that has been known to hunt in large groups, using their numbers to their advantage; however for most of the time they remain solitary. Off South Africa, this species associates closely with the annual sardine run, involving millions of southern African pilchard (''Sardinops sagax''). Like other requiem sharks, it is viviparous, with the developing embryos mainly nourished through a placental connection formed from the depleted yolk sac. Females bear litters of 7 to 24 pups every other year in coastal nursery areas, after a gestation period of 12 or perhaps as long as 21 months. It is extremely slow-growing, with males and females not reaching maturity until 13–19 and 19–20 years of age respectively.

This species is valued by commercial and recreational fisheries throughout its range, and utilized as food. The species population size is unknown, but the IUCN's Red List assesses the species as vulnerable because it is very susceptible to population depletion due to its low growth and reproductive rates and because its numbers are believed to have declined in some areas.

Copper sharks only attack humans infrequently, but the species places tenth in the number of unprovoked attacks on people.

Taxonomy

Because of its very patchy range, the copper shark has been scientifically described several times from different locales. The earliest valid description is presently considered to be British zoologist Albert Günther's account of ''Carcharias brachyurus'' in the 1870 eighth volume of ''Catalogue of the fishes in the British Museum''. The earliest name was once thought to be Auguste Duméril's 1865 ''Carcharias remotus'', until it was found that the type specimen associated with that name is actually a blacknose shark (''C. acronotus''). Thus, this shark was often referred to as ''C. remotus'' in older literature. An even earlier name, Richard Owen's 1853 ''Galeolamna greyi'', is of questionable taxonomic status as it was based solely on a set of now-destroyed jaws that may or may not have belonged to a copper shark. Modern authors have assigned this species to the genus ''Carcharhinus''.

The specific epithet ''brachyurus'' is derived from the Greek ''brachys'' ("short") and ''oura'' ("tail"). The name "whaler" originated in the 19th century, applied by the crews of whaling vessels in the Pacific who saw large sharks of various species congregating around harpooned whale carcasses. This species may also be referred to as black-tipped whaler, cocktail shark or cocktail whaler, or New Zealand whaler, as well as by the shortened "bronze", "bronzie", or "cocktail". Günther originally referred to four syntypes: a stuffed specimen from Antarctica and another from New Zealand, which have since been lost, and two fetuses from Australia that were later discovered to be bull sharks (''C. leucas''). In the interests of taxonomic stability, in 1982 Jack Garrick designated a long female caught off Whanganui, New Zealand as a new type specimen.

Phylogeny and evolution

The first efforts to determine the evolutionary relationships of the copper shark were based on morphology and returned inconclusive results: in 1982 Jack Garrick placed it by itself as a grouping within ''Carcharhinus'', while in 1988 Leonard Compagno placed it in an informal "transitional group" that also contained the blacknose shark (''C. acronotus''), the blacktip reef shark (''C. melanopterus''), the nervous shark (''C. cautus''), the silky shark (''C. falciformis''), and the night shark (''C. signatus''). Gavin Naylor's 1992 allozyme study concluded that the closest relative of the copper shark is the spinner shark (''C. brevipinna''), but could not resolve their wider relationships with the rest of the genus. Fossilized teeth from the copper shark have been recovered from the Pungo River in North Carolina, dating to the Miocene (23–5.3 Ma), from Tuscany, dating to the Pliocene

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