Latin name

Negaprion acutidens

Other name

Sharptooth lemon shark

Identification

A large, stocky, yellowish shark with a broad, blunt snout, narrow teeth with smooth protrusions on both jaws, and dorsal fins of equal size. This species is closely related to Negaprion brevirostris, which lives near the coasts of both Americas. The two species are virtually indistinguishable in appearance, both have a stocky build and broad head, dorsal fins of nearly equal size, and both have a distinct yellow tint to their coloration. However, Negaprion acutidens differs from Negaprion brevirostrisy in having more sickle-shaped fins. 

Features of fish fins

Dorsal spines (total): 0; Anal spines: 0. The sicklefin lemon shark has two dorsal fins of nearly equal size.

Fish colouring

The sicklefin lemon shark has a yellowish brown coloration on the top and a lighter coloration underneath.

Distribution

The range of the sicklefin lemon shark extends from South Africa to the Red Sea (including Mauritius, the Seychelles, and Madagascar), east along the coast of the Indian subcontinent to Southeast Asia, north to Taiwan and the Philippines, and south to New Guinea and the north coast of Australia. The species is also found on many Pacific islands, including New Caledonia, Palau, Marshall Islands, Solomon Islands, Fiji, Vanuatu and French Polynesia. 

Habitat

This shark inhabits the coastal zones of continental or island shelves and can be found from the intertidal zone (littoral zone) to a depth of 92 meters. It prefers environments where the water is dark and calm: bays, coves, inlets, estuaries, lagoons. It is also found over sandbanks and reefs far from the shore. Sometimes individuals will venture out to sea. Young sharp-toothed sharks are often found on shallow reefs and around mangroves, where the water is so shallow that their dorsal fins stick out of the water. 

Size

The Sicklefin Lemon Shark is a large fish, growing up to 3.8 meters in length. 

Behavior

Being slow, the Sicklefin Lemon Shark usually circles quietly over the bottom or lies quietly on the bottom. Unlike most other Requiem sharks, it can actively pump water through its gills. However, it will approach the surface in search of food. This shark rarely goes on a long hunt. 

Food and feeding habits

More than 90% of the shark's diet consists of bottom and coastal bony fishes, including: herring, mullet, mackerel, aterinae, sargans, sillaginidae, sparidae, sea catfish, spinefish, parrotfish, and balloonfishes. Occasionally, sharp-toothed sharks will also eat cephalopods and crustaceans, and adults may prey on stingrays and rays of the rochelle family. Only the largest individuals may prey on stingrays.

Reproduction

The developing embryo is attached to the mother's body by a placenta formed from the emptied yolk sac. The female gives birth to 1-13 (usually 6-12) pups every 2 years, in shallow "nurseries". Pregnancy lasts 10-11 months. The sicklefin lemon shark returns to the place where it was born to breed. Maternity occurs in Madagascar and Aldabra in October-November, near French Polynesia in January. Ovulation and mating of non-pregnant females occur at about the same time. The placenta develops after about 4 months of gestation, when the embryo still has remnants of the external gills. The newborn calf is 45 to 80 centimeters in length. Pups grow slowly, about 12.5 to 15.5 cm per year. At sexual maturity, they grow to 2.2-2.4 m, regardless of sex.

Fishing

These sharks are caught using anchored or floating nets, beach fence nets and longlines. Their meat is sold (raw, salted or dried) for human consumption, their fins are used to make soup, and vitamins are extracted from their liver fat. Due to its low reproductive rate and limited migration, this species is highly vulnerable to overfishing. 

Relationship with a person

Due to its intimidating size and teeth, this shark is considered potentially dangerous. It is certain to defend itself quickly and decisively if touched, harpooned or otherwise provoked or disturbed. Once disturbed, this shark will attack relentlessly. Observations by divers, however, show that sicklefin lemon sharks usually react cautiously and hesitantly to human approach, even when bait is shown. Often the shark will swim away when it sees a diver. Juveniles are reported to be more aggressive and curious than adults. These sharks adapt well to captivity and are often shown in public aquariums.