The Dusky Shark (Carcharhinus obscurus) is a large requiem shark found worldwide in tropical and warm-temperate waters, including the Atlantic, Indian, and Pacific Oceans. The IUCN lists the species as Endangered globally, driven by severe overfishing and its very slow reproductive rate.
Dusky Sharks commonly reach about 3.2 meters (10 feet) long as adults. These species only come together to mate during their mating season, which is during the warmer months. These species like tropical seas for reproduction.
They usually don’t attack humans. They only attack if they feel threatened or if they think that the human is their food. The thing that they like to eat is fish, squid, shrimp, and other things like crabs and crustaceans (things with shells).
Dusky sharks are viviparous, with pups nourished first by a yolk sac and then by a placental connection to the mother. These species live in water from about 10 m to 200 m deep. They can live 40 years or more, with some studies documenting individuals reaching 45+ years. Despite this longevity, the IUCN lists the species as Endangered due to its very slow reproductive rate.
- Status: Endangered (IUCN); North American stocks separately rated Vulnerable by the American Fisheries Society
- Known as: Dusky Shark, Dusky Whaler, Brown Whaler, Bay-shark, Dusky Ground Shark, Shovelnose, Bronze Whaler, and Brown Shark
- Estimated numbers left in the wild: 20% of levels in the 1970s.
Description of Dusky Shark
The Dusky Shark is a fairly large shark included in the requiem shark group. This shark species is related to the Silky Shark, Sandbar Shark, and Galapagos Shark. Requiem sharks are those that are most likely to be involved in attacks on humans, although the animal has instituted few of these. However, because the Dusky Shark inhabits waters often used by humans recreationally, the possibility of attack is still present.
In total, Dusky Sharks have been linked to six attacks on humans and vessels, three of which were indiscriminate and one of which resulted in death, according to the International Shark Attack File.
The female Dusky Shark is larger than the male, is between 320 centimeters and 420 centimeters in length, and can weigh up to 180 kilograms.
Males usually top out at around 150 kilograms. These sharks are bronze/grey to slate or dark slate on their dorsal surfaces and white beneath. They have a rounded shark snout with an impressively toothed mouth opening below.
Distribution and habitat
Dusky Sharks prefer warm waters and will migrate from more temperate regions when colder weather arrives. They have been known to migrate for great distances, up to 3,200 kilometers.
These sharks are very sensitive to the salinity of the water and will avoid estuaries where fresh water may be mixed with salt.
Although these sharks are most common on the continental shelves adjacent to landmasses, they will venture into deeper water near the drop-off point of the shelves.
See Related: Types of Sharks Around the World
Feeding
Dusky Sharks take a wide variety of prey, including bluefish, octopuses, squid, groupers, skates, mullet, sharks, and herring. They will also eat refuse that has been dumped into the ocean.
Breeding
Springtime is when Dusky Sharks mate and the gestation period is about 8 months. The embryo sharks initially receive nourishment from a yolk sac, but when this has been used up, a placental attachment with the mother’s body is made.
The newborn Dusky Shark is approximately 1 meter at birth, and it takes the female a year to recover from the ‘pregnancy’ before she is ready to mate once again. A litter will consist of between 6 and 14 young. These sharks can live 40 years or more, with some studies documenting individuals reaching 45+ years.
Fun fact: Female Dusky Sharks may retain sperm when they do not encounter possible mates frequently.
Location
The Dusky Shark has a worldwide distribution along continental shelves. They are found along the Atlantic coast from Maine down to Argentina. On the Pacific side, Dusky Sharks live along the California coast. They surround Australia and live around the coastal regions of most of Africa.
They can be found in great numbers in the seas of the western and central Mediterranean, the Atlantic Ocean, the Atlantic Ocean, the Atlantic Ocean, the Canary Islands, Senegal, Sierra Leone, and even the waters of Spain, Portugal, Madeira, and Morocco. They are occasionally spotted in the Arabian Sea, the Red Sea, and the Bay of Bengal. They also populate the great Pacific Ocean.
About the Dusky Shark
The Dusky Shark (Carcharhinus obscurus) is one of the largest members of its genus. It commonly reaches about 3.2 meters (10 feet) long and 160–180 kg (350–400 lbs), with a maximum recorded length of 4.2 meters (14 feet) and weight of roughly 370 kg (about 820 lbs). Females are larger than males.
The slender, streamlined form of this shark has a very broad snout that is no longer than the width of the mouth. The nostrils are preceded by small flaps of skin that have not yet developed. The eyes are medium in size and circular in shape, with nictitating membranes (protective third eyelids) to protect them from injury.
The mouth has very short, subtle furrows at the corners and contains 13-15 (typically 14) tooth rows on either side of both jaws.
The upper teeth are broad, triangular, and oblique. They have strong coarse serrations. The lower teeth are narrower and upright with finer serrations. There are five pairs of gill slits that are fairly long.
Dusky Sharks are often confused with the other requiem shark species, like Silky Sharks, Sandbar Sharks, and Galapagos Sharks. The Dusky Shark is the hardest to tell apart from the rest. Its first dorsal fin is set further back than the free tips of its pectoral fins, and its other fins are proportionally smaller and swept back.
Dusky Shark habitat
Dusky Sharks are year-round residents of coastal areas, showing up in inshore bays to the outer continental shelf and adjacent oceanic seas. This species’ adults generally avoid regions with low salinity levels and seldom enter estuaries.
Along the east coast of the United States, nursery grounds have been found in shallow inshore waters. Nursery grounds have also been discovered off the southwest coast of Australia.
The Dusky Shark is found in both tropical and temperate waters, making it a truly global species. These species migrate across broad areas, ranging from hundreds of kilometers to thousands of kilometers in each migration event. Animals move north in the summer and south in the winter in the western Atlantic and eastern Pacific.
Dusky Sharks migrate north in the austral winter-spring and south in the austral summer-autumn, respectively, in South Africa and Australia. They are known to be split into groups based on size and gender.
See Related: Black Tip Sharks: Are They Endangered?
Dusky Shark diet
Dusky Sharks are most often found in near-shore bays, on the outer continental shelf, and in adjacent oceanic seas. They are generally active during the day and congregate offshore waters, but they may be seen at the coast where they go for food.
These species migrate long distances, moving via the seas to Australia and South Africa. Dusky Sharks are divided into genders and sizes, with the biggest ones traveling north or south according to the season of the year.
The diet of these creatures consists largely of bony fishes, squid, octopus, crabs, oysters, seals, dolphins, other sharks, rabbits, and seabirds. Bony fish are their favorite. Despite some regional fishing restrictions, they remain at risk of extinction due to their slow reproduction and continued targeting for the shark fin trade. They have a voracious appetite and can devour 60 pounds (about 25 kg) of food in one sitting.
Dusky Sharks are social creatures. They usually swim in groups. Many things present a potential predator to them, including killer whales, blue sharks, tuna, sea lions, and humans.
Their babies are called pups, and like most sharks, receive no parental care after birth. Dusky Sharks mate during the summer and give birth to their pups in the spring. Adults typically grow to about 10 feet long and weigh 350–400 pounds, with the largest recorded individuals reaching around 820 pounds.
Dusky Shark conservation status
Sharks from around the world face different threats. Northwest Atlantic and Gulf of Mexico Dusky Shark populations had dropped to just 15–20% of mid-1970s levels by the mid-2000s, one of the steepest declines recorded among large sharks.
Some sharks migrate to the Americas, Africa, Australia, and parts of Asia. The IUCN lists the Dusky Shark as Endangered globally (the American Fisheries Society separately rates North American stocks as Vulnerable). International protections for this migratory species remain limited, and its populations are being caught at unsustainably high rates for their fins.
There were a lot of sharks caught in the past few years, but not as many Dusky Sharks. Scientists think this is because there are fewer of them. There are no ways to protect them because they live in the ocean. This animal has been under a lot of pressure since the 1970s. The increased pressure may be pushing it to the edge of collapse now.
The lack of management, unsustainable fishing practices, and low reproduction rate of the species means it needs to be better managed. Putting it in Appendix II is the first step in achieving the protection needed.
Conservation
Threats
The trade of shark fins has resulted in significant losses in Dusky Sharks. It is estimated that about ¾ million of these sharks are killed for shark fin trade every year.
Dusky Sharks are also victims of commercial and recreational fishing. These sharks get caught in shark nets often. This is causing a decline in their population, especially in Australia and South Africa. Aside from this, young Dusky Sharks can be predated by larger sharks like bull sharks.
The Dusky Shark is also taken for its oil, and the skin is made into leather. Because of the ‘fight’ the Dusky Shark gives when hooked, it is prized in sport fishing.
Conservation efforts
Due to the declining numbers of Dusky Sharks off the United States coast, commercial fishing of this species is forbidden on the US coasts. Sportfishing, however, is allowed.
The Dusky Shark has received little to no formal protection in most other parts of the world.
Organisations
Oceana
Oceana is the largest international organization focused only on ocean conservation, protecting marine ecosystems and endangered species such as the Dusky Shark.
Conclusion
Dusky Sharks are sometimes confused with other requiem sharks, such as the Silky, Sandbar, and Galapagos Sharks, due to their similar shape and coloring. They can be found worldwide in the Pacific, Atlantic, and Indian Oceans.
Dusky Sharks favor warm and temperate waters and migrate seasonally to track preferred temperatures; unlike marine mammals, sharks have no blubber layer and instead rely on their size, muscle mass, and swimming activity to help manage body temperature.
This species feeds on fish like herring and mackerel, along with squid and octopus. Its population has declined steeply since the 1970s, and the IUCN currently lists the Dusky Shark as Endangered.
The IUCN classifies the Dusky Shark as Endangered. They are occasionally caught for their liver oil, meat, and fins, and most of the world’s oceans still lack meaningful catch limits or management for the species.
FAQ
What is Dusky Shark?
The Dusky Shark (Carcharhinus obscurus) is a large requiem shark found worldwide in tropical and warm-temperate waters, including the Atlantic, Pacific, and Indian Oceans. It is generally dark gray or bronze above with a white underside.
Dusky Sharks have a low ridge running along the midline between their two dorsal fins, a key identification feature that distinguishes them from similar-looking requiem sharks.
Dusky Sharks are frequently taken as bycatch in commercial fisheries worldwide, and their fins are highly valued in the shark fin trade — a major driver of the species’ Endangered status.
Would Dusky Shark make a good pet?
Dusky Sharks would not make suitable pets. They are large, wide-ranging wild predators that need vast ocean territory, and keeping one in captivity would be both impractical and harmful to the animal.
While Dusky Sharks are naturally curious and will investigate their surroundings while hunting, this is normal wild behavior, not a trait that makes them safe or appropriate to keep as pets.
As apex predators, Dusky Sharks require large amounts of live or fresh prey and a huge range to hunt in — needs that cannot be met in a home aquarium.
In the wild, Dusky Sharks range across huge territories, either alone or in loose aggregations, an existence that cannot be replicated outside specialized research or conservation facilities. This species is best appreciated in the wild or through conservation organizations, not kept as a pet.
Are Dusky Sharks endangered?
Because of its slow growth, late maturity, and heavy targeting in global fisheries — including the shark fin trade — the Dusky Shark’s population has been closely studied and is classified as Endangered by the IUCN, not data deficient. Steep regional population declines are part of why these species being classified as endangered are now recognized as being at real risk of extinction.
Also known as Carcharhinus obscurus, Dusky Sharks are in fact heavily targeted in commercial and recreational fisheries and the shark fin trade. They commonly grow to about 10 feet (3.2 m) long and 160–180 kg (350–400 lbs), with the largest recorded individuals reaching around 4.2 m and 370 kg. They are indicators of healthy, normal marine ecosystems.
Dusky Sharks tend to stay far away from humans and human activity, so they do not typically interact with people or come into contact with them very often. Their diet mainly consists of fish, including mackerels, herrings, anchovies, and sardines.
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