Bronze Whaler or Copper Shark
A frequent visitor on the Sardine Run
The Bronze Whaler, Copper shark, or Narrowtooth shark (Carcharhinus brachyurus) is a species of requiem shark, family Carcharhinidae, and the only member of its genus found mostly at temperate latitudes. It can be found from brackish rivers and estuaries, to shallow bays and harbors, to offshore waters 330 feet deep or more.
Bronze Whaler sharks only attack humans infrequently, but the species places tenth in the number of unprovoked attacks on people. It is a fast-swimming shark that is regularly fished for recreation.
Family: Carcharhinidae – Requiem sharks
Common Name– Ground Sharks
Common Name– Requiem Sharks: A.K.A. Narrowtooth shark
Status: IUCN Red List NEAR THREATENED
Average Size and Length: The Bronze Whaler is reported to have reached a length of 11 feet. Typically, around 9.8 feet.
Average Weight: It has been reported to reach a mass of 672 pounds.
Teeth and Jaw: The Bronze Whaler or Copper shark mouth has short, subtle furrows at the corners and contains 29–35 upper tooth rows and 29–33 lower tooth rows. What is interesting is the upper teeth of adult males are longer, narrower, more curved, and more finely serrated than those of adult females and juveniles. The teeth are serrated with single narrow cusps; the upper teeth have a distinctive hooked shape and become more angled towards the corners of the jaw, while the lower teeth are upright.
Head: The Bronze Whaler snout is long and pointed, with the nostrils that have flaps of skin. The eyes are large and round, and have nictitating membranes.
Tail: The caudal fin of the Copper shark or the Bronze Whaler has a well-developed lower lobe and a deep ventral notch near the tip of the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The Bronze Whaler is found in temperate waters above 54 degrees F, instead of tropical waters like the other sharks of its genus.
In the Indo-Pacific, the Bronze Whaler is found from Japan (excluding Hokkaido) to the East China Sea and southern Russia, off southern Australia (mostly between Sydney and Perth but occasionally further north), and around New Zealand but not as far as the Kermadec Islands; there are also unconfirmed reports from the Seychelles and the Gulf of Thailand.
In the eastern Pacific, the Bronze Whaler can be found from Peru to northern Chile, and from Mexico to Point Conception, California, including the Gulf of California. The Bronze Whaler or Copper shark is common off parts of Argentina, South Africa, Australia, and New Zealand.
In the Atlantic, the Bronze Whaler can be found from the Mediterranean Sea to Morocco and the Canary Islands, off Argentina, and off Namibia and South Africa (where there may be two separate populations). There are infrequent records possibly off of the Gulf of Mexico, Mauritania, and the Gulf of Guinea.
Bronze Whalers or Copper sharks can be found from the surf zone to slightly beyond the continental shelf in the open ocean, diving to depths of 330 feet or more. Bronze Whalers frequently can be found in harbors, bays, and other shallow habitats. They also can be found in rocky areas and offshore islands.
The Bronze Whaler is tolerant of low and changing salinities, and has been reported from estuaries and the lower reaches of large rivers. Juveniles inhabit inshore waters less than 98 feet deep throughout the year. Adult Copper sharks or Bronze Whalers are usually further offshore and regularly approach the coast only in spring and summer, when large aggregations can be readily observed in shallow water. They participate in seasonal migrations that are a direct response to availability of prey, reproductive procedures and temperature changes. The movement patterns are different in the age of the sharks and male and female. Adult female Copper sharks or Bronze Whalers and juveniles spend winter in the subtropics and generally shift to higher latitudes as spring nears, with pregnant females also moving towards the coast to give birth in inshore nursery areas. Adult males Bronze Whalers remain in the subtropics for most of the year, except in late winter or spring when they also move into higher latitudes, in time to encounter and mate with post-partum females dispersing from the nurseries. During migrations, individual sharks have been recorded traveling up to 820 miles. It is philopatric.
Diet: The Bronze Whaler does prefer to feed towards the bottom of the water column instead of the top. It loves to eat cephalopods like cuttlefish, octopus and squid. The Bronze Whaler will eat a wide range of bony fishes, like jacks, gurnards, flatfishes, hakes, catfishes, mullets, Australian salmon, sea breams, smelts, tunas, anchovies and sardines. The Copper shark or Bronze Whaler will even eat cartilaginous fishes, including dogfish sharks, stingrays, skates, electric rays, and even sawfishes. Sharks that are over 6.6 feet in length tend to eat cartilaginous fish and cephalopods more than smaller sharks. On occasion, it will act as a scavenger on already dead marine mammals, but Bronze Whalers do not actively prey on marine mammals
Young Bronze Whaler sharks will also eat scyphozoan jellyfish and crustaceans, including mud shrimps and penaeid prawns.
The predominant prey of the South African species is the southern African pilchard which comprise 69–95% of its diet. Every winter, schools of Bronze Whalers or Copper sharks follow the “run” of the pilchard from the Eastern Cape to KwaZulu-Natal. The gathering of millions of forage fish attracts an assembly of predators, including several species of sharks, of which Bronze Whaler or Copper sharks are the most numerous. One interesting fact about their behavior is that a large number of Bronze Whalers have been observed hunting together in an apparently cooperative fashion. Small schooling fish are “herded” into a tight ball, at which point each shark swims through in turn with its mouth open to feed. For groups of tuna and larger prey, the pursuing sharks may adopt a “wing” formation to force their prey closer together, with each shark targeting a particular fish and attacking in turn. Harry has seen this behavior firsthand. In False Bay, South Africa, this species reportedly follows seine net fishing vessels.
Aesthetic Identification: The Bronze Whaler or Copper shark is commonly mistaken for other species of sharks. The Bronze Whaler is bronze to olive-gray above with a metallic sheen and sometimes a pink cast, darkening towards the fin tips and margins. The color fades quickly to a dull gray-brown after death. They are counter-shaded white underneath, which extends onto the flanks as a prominent band. It has five long pairs of gill slits and has a slender, streamlined body with a slightly arched profile just behind the head.
The pectoral fins of the Bronze Whaler are large, pointed, and falcate. The first dorsal fin is tall, with a pointed apex and a concave trailing margin; its origin lies about even with the tips of the pectoral fins. The second dorsal fin is small and low, and positioned about opposite to the anal fin. There is usually no ridge between the dorsal fins.
Biology and Reproduction: The Bronze Whaler is viviparous. Males do bite females during mating. In the Southern Hemisphere, mating takes place from October to December (spring and early summer), when both sexes have migrated into offshore waters at higher latitudes.
Birthing seems to occur from June to January, peaking in October and November. Nurseries are found inshore. Some known nursery areas are off northern North Island from Waimea Inlet to Hawke Bay for New Zealand Bronze Whalers, off Albany, near Gulf St Vincent, and in Port Phillip Bay for Australian sharks, off Niigata (Japan) for northwestern Pacific sharks, off the Eastern Cape for South Africa sharks, off Rhodes (Greece), Nice (France), and Al Hoceima (Morocco) for Mediterranean sharks, off Río de Oro (Western Sahara) for northwest African Bronze Whalers, off Rio de Janeiro (Brazil) and Buenos Aires and Bahía Blanca (Argentina) for southwestern Atlantic sharks, and off Paita and Guanape Cove (Peru), in Sebastián Vizcaíno Bay (Mexico), and in and around San Diego Bay for eastern Pacific Bronze Whalers.
Bronze Whalers have an estimated gestation period of 12 months, although some research suggests between a 15–21-month long gestation period instead. Females produce litters every other year, with the number of pups ranging from 7 to 24 and averaging 15 or 16. It is interesting that Bronze Whalers off of Baja and California have fewer pups than other Bronze Whalers of different areas. The newborns measure 22–26 inches long.
The Bronze Whaler is extremely slow-growing. Off of South Africa, males reach sexual maturity at 6.6–7.9 feet long and an age of 13–19 years. Females mature at 7.5–8.2 feet long and an age of 19–20 years. Australia is comparable, but the Bronze Whalers of Argentina age smaller in comparison.
The maximum lifespan is at least 30 years for males and 25 years for females.
Behavioral Traits, Sensing and Intelligence: As mentioned previously, the Bronze Whaler actively participates socially with other sharks during the Sardine Run in cooperative efforts, yet typical behavior is to hunt alone. We can guess that the Bronze Whaler does have intelligence when it comes to hunting based on this data. However, little research has been done, and there is a lot of room to study the behavior, intelligence and sensing of the Bronze Whaler or Copper shark.
The Bronze Whaler is often victim to bycatch and also commercial fishing. Its meat is consumed by humans.
Bronze Whaler or Copper Shark Recorded Attacks on Humans: Bronze Whaler or Copper shark attack humans infrequently, but it places tenth in the number of unprovoked attacks on people. During the tracking period through 2013, the University of Florida attributed 20 attacks to the species (UF, 2014).