Blacktip Reef Shark

Blacktip reef sharks are the most common sharks in reef systems in the Pacific and Indian Oceans. These sharks belong to the family Carcharhinidae, also known as requiem sharks. They inhabit many shallow coastal waters and tropical reefs, creating nurseries for their young.

Blacktip Reef Shark Facts

• Their fins are desired for shark fin soup, and they’re hunted by commercial fishers.
• Blacktip reef sharks congregate to create pup nurseries in shallow coastal waters.
• Juveniles grow quickly in their first couple of years, reaching up to nine inches.

Classification and Scientific Name of the Blacktip Reef Shark

Blacktip reef sharks (Carcharhinus melanopterus) are a species of requiem sharks. They belong to the family Carcharhinidae. Sharks in this family live in tropical or warm waters; a few, like the bull shark, can also live in brackish or fresh water. They typically have rounded snouts and blade-shaped teeth.

This shark’s genus name is Carcharhinus, and it’s a combination of the Greek words karkaros, meaning jagged or sharpened, and rhino, which means nose. Its specific name is melanopterus, and it means black-fin.

Identifying the Blacktip Reef Shark: Appearance and Description

This shark has a classic “shark look” and a powerful, streamlined build. It has somewhat large eyes with a third eyelid, a roundish snout, and lobed skin flaps in front of each of its nostrils. Like other requiem sharks, their teeth are serrated and triangular-shaped.

A medium-sized coastal shark, the blacktip reef shark generally reaches about five feet long, and can grow up to six feet It’s easy to identify, with black tips and white borders on all fins; however, these markings are most noticeable on its first dorsal fin and lower lobe of the caudal fin. These markings are a defining characteristic of the species. Its back is grayish-brown with a white belly; the white stripe on its flank starts below its second dorsal fin and ends about halfway toward the nose. It doesn’t have a ridge between its dorsal fins; the pectoral fins are sickle-shaped and taper to points.

Blacktip Reef Shark Distribution and Habitat

These sharks inhabit many of the coastal tropical waters of the Pacific and Indian Oceans. This includes East Africa, the Persian Gulf, and the Red Sea, all the way to the Tuamotu Archipelago and the Hawaiian Islands. Blacktip reef sharks also occur as far north as Japan and south to the north coast of Australia. They sometimes travel through the Suez Canal into the eastern areas of the Mediterranean.

They’re a fairly widespread species, but individual sharks often have small home ranges that they don’t migrate from, although a few may go farther looking for prey. This species stays pretty close to shore, to a depth of about 75 meters. They’re found in shallow water above coral reefs, in the intertidal zone, and near drop-offs at the edges of reefs. They’ve also been found in mangroves where they follow the tide in and out. These reef sharks can tolerate brackish water, such as in estuaries and mangroves, but are not known to inhabit true freshwater environments.

Pups hide in shallow nurseries, so bigger sharks don’t eat them, and begin to venture out when they’re bigger. Juveniles often form large groups in mangrove swamps or over sand flats. The water frequently only just covers their bodies, and they move in and out with the tides; sometimes, they move across seaweed beds and flooded coral platforms.

Conservation and Population

Like many reef inhabitants, blacktip reef sharks have seen population reductions. The IUCN published a report in 2020 that estimated an approximate 30 – 49% population reduction over the last three generations (44 years). The report took data from underwater video stations in 254 reefs throughout its range; consequently, they assessed the blacktip reef shark as vulnerable.

Part of the challenge for this shark is that it reproduces slowly, and the females typically give birth to 2-5 pups per litter, though in some regions litters can be as large as 4-10 pups, and the reproductive cycle may be annual or biennial depending on location. However, human activities also threaten this shark. It’s both actively hunted by commercial fisheries (both large and small scale) and taken accidentally as bycatch. Commercial fisheries use a variety of methods to catch it, including longline, gillnet, handline, and trawls. The blacktip reef shark is marketed for a variety of products — fins, skin, meat, teeth, and liver. The habitat quality of coral reefs has also declined due to pollution and destructive fishing practices.

That’s not to say that the species is in decline everywhere. It’s not. Some locations have healthy populations of blacktip reef sharks. Some areas have protections in place, and others don’t.

One protected area is Palmyra Atoll. It’s a U.S. Fish & Wildlife Service National Wildlife Refuge and a Nature Conservancy preserve. In the surrounding waters, there are 15,000 acres of nearly pristine coral reefs. Except for the U.S. military during WWII, there has never been a permanent human settlement on the Atoll. Scientists use this and areas like it to help provide a baseline of what a healthy coral reef looks like.

Predators and Prey of Blacktip Reef Sharks

Scientists believe that blacktip, Caribbean, and other reef sharks play a significant role in shaping the structure of coral reef communities. Blacktip reef sharks band together to herd schools of mullet towards the shore so they can feed more efficiently. They also eat groupers, surgeonfish, grunters, jacks, smelt-whitings, mojarras, and wrasses. Occasionally, they also take shrimp and cephalopods like squid or octopus. Scientists have seen the Palmyra Atoll sharks take seabird chicks that fall into the water from their nests.

The ampullae of Lorenzini also help the sharks locate their prey via electroreception. These sharks do not have cone cells in their retinas. It limits their ability to discern colors and details. They are more sensitive to contrast and movement in low light, and blacktip reef sharks become more confident when there are others of their species nearby.

Juveniles and smaller sharks are preyed upon by bigger fishes, including groupers; other sharks also prey on them, including grey reef sharks, tiger sharks, and others of their own species.

Other Threats

Blacktip reef sharks are often hunted for their meat and fins because many people find them tasty. The IUCN lists them as vulnerable, and their biggest threat is that their preference for shallow water puts them at risk. Coastal development often brings with it the destruction of nursery sites that they need for their young.

Reproduction and Lifespan of the Blacktip Reef Shark

Like other requiem sharks, this species is viviparous. The timing varies depending upon location, with some females mating yearly or every other year. It may be that the variance in schedules is due to more competition for resources; the water temperature may also play a role. Those off the coast of northern Australia mate yearly; that’s also true for French Polynesia. However, off the coast of Aldabra, the females mate every other year. This area has intense competition for food, both among the blacktip reef sharks and other species.

In any case, female blacktip reef sharks typically give birth to 2-5 pups per litter, though litters of up to 10 pups have been recorded in some regions. These sharks set up nurseries in shallow water close to the shore. There, the pups live until they’re a little bigger to help them avoid being eaten by an even bigger fish.

Blacktip Reef Shark in Fishing and Cooking

These sharks are sometimes caught as bycatch, but they’re also frequently the target. As previously mentioned, many people find blacktip reef sharks delicious. Their fins are often used in shark fin soup, and their meat is also marketable.