Bronze Whaler Shark

“Bronze whaler sharks often hunt in large groups.”

Bronze Whaler Shark Facts

• Also known as the copper shark
• The bronze whaler shark is a viviparous fish. This means the female carries the young as mammals do, and they’re born alive after developing inside her. 
• The bronze whaler is sensitive to the salinity of the water around it and migrates accordingly. 
• Bronze whaler sharks tend to hunt in large groups, giving them an advantage, especially when they encounter larger prey. 
• Young bronze whaler sharks inhabit shallow waters of less than 100 feet until they become adults. 
• Male and female bronze whaler sharks don’t live in the same location.

Classification and Scientific Name

The bronze whaler shark goes by the scientific name of Carcharhinus brachyurus. It belongs to the order Carcharhiniformes, which is considered the largest order of sharks on Earth. It also belongs to the family Carcharhinidae along with seven other shark families. 

The family Carcharhinidae, to which this shark belongs, is also known as the requiem sharks. These migratory sharks live most of their lives in warm seas. However, they may also live in brackish or even fresh water. Requiem sharks are known to be viviparous fish that give birth to live young. 

Appearance 

The bronze whaler shark is a large fish with a classic shark appearance. It features a long and moderately rounded snout with narrow hook-shaped teeth. The male and female have similar appearances, although the male is slightly bigger. The males also have proportionately longer teeth. 

Bronze whaler sharks typically grow to a maximum length of around 9.8 feet. However, there are rare records of males growing as long as 11.5 feet. The estimated maximum weight they reach is 672 pounds. Bronze whaler sharks have circular and relatively large eyes. Their pectoral fins are moderately large and typically feature narrowly rounded or pointed tips. They do not have an inner dorsal fin. However, their caudal fin typically features a bulge close to the base of its front edge. 

The dorsal side of the bronze whaler shark is bronze-gray or olive-gray, which is where the name comes from. The ventral surface is white. They have some dark markings on the edge of their fins. These markings are quite similar to that of the blacktip shark or spinner shark. This is why both species are often confused with each other. Their main distinguishing feature is the distinctive upper teeth and the lack of pronounced markings. They also don’t have an inner dorsal ridge like these other species. 

Distribution and Location

Bronze whaler sharks are typically found in temperate waters and come together at certain times, such as for group hunting or migration. They are likely to inhabit the deep waters of the Atlantic, usually off the coast of Australia, South Africa, and New Zealand. However, they may also venture close to the coastlines of various offshore islands, artificial harbors, and inlet waterways. 

Some populations of bronze whaler sharks have been spotted in the Mediterranean, off the coast of Argentina, around the Gulf of Mexico, and in the Indo-Pacific regions. Bronze whalers are highly migratory. They change locations due to food availability, seasonally based on water temperatures, and may also move due to changes in salinity. Males and females generally congregate during mating season, but can also mix together at other times. 

Population and Habitat

The UN has designated the bronze whaler shark as near threatened because the species population is growing thinner due to commercial fishing. Like most sharks, the species also has a low reproduction rate which is another reason for the declining population. Currently, there is a catch-and-release program in New Zealand and Namibia to preserve the population of bronze whaler sharks. Commercial fishing is prohibited in these places, and hobby or recreational fishermen must release their catches back to the sea. 

Bronze whaler sharks live in depths of around 330 feet. However, juveniles may stay in shallow water until they mature. They also tend to migrate toward the coast during spring and summer months. These sharks are sensitive to water salinity and are thought to migrate to different places based on changes in water salinity. However, they generally migrate due to food availability, temperature changes, and reproductive reasons. 

Predators and Prey

Bronze whaler sharks are fast-swimming predators that mainly feed on cephalopods and bony fish. However, they may also feed on other cartilaginous fish. Bronze whaler sharks hunt in large groups, which allows them to utilize their numbers to their advantage. 

Bronze whaler sharks utilize a herding strategy to feed. They work collectively to round up schools of small fish like sardines or flatfish into a tight ball. Then the bronze whaler sharks take turns swimming through the massive ball of fish with their mouths wide open, capturing multiple fish as they pass through. Their group hunting strategy gives them a higher success rate than they would have feeding alone.

What does a bronze whaler eat? 

Bronze whaler sharks have a diverse diet that consists of cephalopods such as squids and octopuses. They also feed on bony fish such as sardines, flatfish, and mullets. During the winter months, large populations of bronze whaler sharks follow shoals of sardines on the migratory journey along the coast of Southern Natal. Adults may also attack other cartilaginous fish like sharks and stingrays.

What eats a bronze whaler?

Larger sharks can prey on juvenile bronze whalers. However, commercial and recreational fishing may be the biggest threat to the bronze whaler population. Humans fish bronze whaler sharks for food. Due to overfishing and the slow reproduction rate of this species, the IUCN has certified the species as near threatened. 

Bronze Whaler Shark Reproduction and Lifespan

The bronze whaler shark is a viviparous placental species like other requiem sharks. This means their young are carried in a placenta connected to the mother during gestation and born alive. The gestation period usually lasts about 12 months, and the species reproduces once every two years. 

Limited data is available regarding when the bronze whaler shark’s reproduction takes place. Female shark litters can vary from 7-24 pups with an average of 15 pups, and the juveniles remain in inshore bays until they’re mature enough to venture deeper into the water. 

The age of maturity for bronze whaler sharks is 13-19 years for males. Females become mature when they’re about 20 years old. The maximum lifespan is about 30 years for males, while females may live for about 25 years.