Ganges shark

Ganges shark, (Glyphis gangeticus), species of river shark endemic to shallow tropical freshwater, brackish water, and coastal marine estuary habitats that border the Indian Ocean and western Pacific Ocean. The Ganges shark is extremely rare and seldom observed in the wild, and evidence of its presence is largely drawn from fishery reports and the discovery of Ganges shark fins in fish-processing centers and markets. No Ganges shark has been encountered by wildlife officials or members of the fishing industry since 2016. Wildlife officials and ecologists estimate that the species is made up of fewer than 240 mature individuals. The Ganges shark was previously classified as a gray shark in genus Carcharhinus, but most taxonomies have moved it to genus Glyphis, which it shares with the speartooth shark (G. glyphis).

Records collected by the fishing industry, wildlife officials, and others suggest that the species inhabits a handful of strongholds from coastal Pakistan eastward to the northeastern part of Malaysia’s Sabah state on Borneo. Most records of the shark come from the Hooghly River, the major arm of the Ganges River flowing through West Bengal state in India. Some specimens are reported from the Sundarbans and other parts of the Ganges-Brahmaputra delta and from the Indus River estuary in Pakistan. Several specimens collected between 1996 and 2003 from the Kinabatangan River of Malaysian Borneo were first placed in the species G. fowlerae; however, on the basis of follow-up genetic studies, they were later reclassified as Ganges sharks.

Natural history

The Ganges shark is an enigmatic species, and its natural history remains incomplete, since much of what is known to science comes from fishers’ reports and a few dozen captured specimens. Superficially, Ganges sharks are dark gray with white undersides. They are stocky with rounded snouts and prominent hooked caudal fins. They have small eyes that are tilted upward, a trait that suggests an adaptation to the murky river waters, and large serrated teeth. Although the largest individuals can grow to lengths up to about 2.75 meters (9 feet), Ganges sharks average about 1.8 meters (5.8 feet) fully grown, and there is some evidence that females tend to be larger than males.

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10 Critically Endangered Animals of India: Ganges shark (Glyphis gangeticus)

These sharks are thought to be bottom-feeders, preying on fish that frequent the floors of rivers and estuaries. Although the species is associated with attacks on people because of the length of its teeth, many authorities note that Ganges sharks are likely mistaken for bull sharks (Carcharhinus leucas), which hunt in the same habitats. The Ganges shark has no known natural predators, though some sources speculate that bull sharks might prey on juveniles. Ganges sharks, however, have been harvested for their oil, meat, and fins by subsistence and industrial fishing operations alike.

Very little is known about the shark’s mating habits and reproductive biology. On the basis of the physical traits and behaviors of other sharks within the family Carcharhinidae, several authorities assume that both sexes have multiple mates in a breeding season, that the species is viviparous (that is, a placenta connects each yolk sac with the mother shark, and young are born alive), and that Ganges sharks live about 12–15 years.

Conservation status

The Ganges shark ranks among the 20 most threatened shark species globally. The International Union for Conservation of Nature (IUCN) has classified the Ganges shark as a critically endangered species since 2021. The primary threat to the species is from small-scale and subsistence fishing operations, which capture the Ganges shark as bycatch. In addition, the shark’s riverine habitat has been degraded by pollution (which often takes the form of discharge from chemical plants) and decreased water quality that stems from sand mining and soil runoff from land-clearing efforts adjacent to riverbeds. The construction of hydroelectric dams and barrages in the lower reaches of rivers have also fragmented much of the shark’s remaining usable habitat.