Author: (Müller and Henle, 1839)
Field Marks:
A fairly stocky requiem shark with a broadly rounded short snout, preoral snout much shorter than mouth width but with a rather long preorbital snout, minute eyes, first dorsal origin over rear ends of pectoral bases, second dorsal rather large, about 1/2 height of first dorsal, upper teeth with high, broad, serrated triangular cusps, lower anterior teeth with long, hooked, protruding cusps having unserrated cutting edges not confined to spearlike tips and crown feet with low cusplets, no interdorsal ridge, upper precaudal pit longitudinal, no conspicuous markings.
Diagnostic Features:
First few anterior teeth in lower jaw with cutting edges along entire cusp, giving the cusps a clawlike shape, and low cusplets; second dorsal lower, about half the height of first dorsal.
Geographical Distribution:
Indo-West Pacific: Definitely known from the Hooghly River, Ganges system, West Bengal, India, and likely from the vicinity of Karachi, Pakistan (see remarks below).
Habitat and Biology:
A poorly known freshwater riverine and possibly inshore marine and estuarine shark. Probably viviparous. The Ganges shark has a horrific reputation as a maneater in the GangesHooghly system, but this is unproven (see remarks below).
Size:
Maximum possibly to at least 204 cm (type of Carcharias murrayi); adult or adolescent male 178 cm (stuffed syntype); newborn specimens 56 to 61 cm.
Interest to Fisheries:
Probably fished in the Ganges-Hooghly system, but details unknown.
Remarks:
The elusive Ganges shark has been famed and fabled for its occurrence in fresh water as well as for its bloody reputation as a maneater there. Originally known only from the type locality, it was gradually recorded from the entire span of the Indo-West Pacific until Fowler (1941), in a masterpiece of compilation bearing little relationship to reality, recorded the species from Arabia and India to Borneo, Viet Nam, China, Japan, Australia, the Philippines, and Fiji and the Hawaiian Islands. However, with the critical survey of carcharhinids begun in the early 1960s, most of the marine and freshwater records of the Ganges shark could not be substantiated and many were found to be based on Carcharhinus leucas, C. amboinensis and other species (see Garrick and Schultz, 1963; Boeseman, 1964; Garrick, 1967, 1982; Bass, D'Aubrey and Kistnasamy (1973). Boeseman (1964) noted that "most of the recorded C. gyngeticus from outside the Indo-Pakistan Peninsula (excepting those from Japan and possibly, from Viti-Levu, Fiji Islands), are identical with C. leucas Müller and Henle.", and since then confirmation of records of the species from Japan and Fiji has not been forthcoming. Lineaweaver and Backus (1970) and Ellis (1975, 1983) even considered the Ganges shark a synonym of Carcharhinus leucas, although Garrick (1982) recognized it as distinct.
During a trip to India in 1982 the writer discovered an additional specimen of G. gangeticus in the fish collection of the Zoological Survey of India in Calcutta (ZSI 8067, 61 cm newborn female, misidentified as Carcharhinus temmincki), collected by Dr J. Anderson from the Hooghly River on 4 April 1867. This confirmed Garrick's recognition of the species, but sheds little additional light on its biology. It is apparently only the fourth verified specimen of this rare shark, including the two syntypes (one lost) and possibly the holotype of Carcharias murrayi (also lost), and hence is one of two extant specimens in museum collections. Garrick (1982) suggested that Carcharias murrayi is a possible synonym of this species, with which the writer concurs.
The writer examined another specimen in the Zoological Survey collections labelled Squalus gangeticus (ZSI 10250, 65 cm newborn male) but bearing the same data (Hooghly River, collected by Dr J. Anderson, 4 April 1867) as the true gangeticus specimen; but this turned out to be the circumtropical bull shark, Carcharhinus leucas. Although Garrick (1982) had not examined specimens of leucas from the Indian subcontinent, the writer found leucas material from Cochin and Bombay as well as the Hooghly specimen.
Thus there are two species of sharks in the Hooghly River, and, with the well-known affinities of C. leucas for fresh water, probably two Ganges River sharks as well. The hideous reputation of the true Ganges shark grew on the assumption that there was only one species of shark in fresh water in the Hooghly-Ganges system, which was responsible for the numerous attacks on people reported by Day (1878) and other writers. However, the Ganges shark may eventually have to pass on much or all of its notoriety to the more prosaic but perhaps more dangerous and formidable bull shark. In comparison with Carcharhinus leucas, Glyphis gangeticus has much narrower, higher, upper teeth and slender-cusped, less heavily built lower teeth. The teeth of the Ganges shark appear more suitable for fish-impaling and less useful for dismembering tough mammalian prey than the very stout teeth of the bull shark. The presence of the bull shark (one of the most dangerous living species) in the Hooghly and perhaps the Ganges along with readily available human prey and mammalian carrion suggests that with widespread confusion of this shark and C. leucas in India and elsewhere its bad reputation must be considered uncertain at best. The Ganges shark is potentially dangerous because of its size and large teeth, but at present its relation to humans is a mystery, along with almost all other aspects of its biology. Although sharks are currently caught in the Ganges system (P.K. Talwar, pers. comm.), it is not known how common the true Ganges shark is relative to the bull shark. It is also quite uncertain how well the Ganges shark is adapted to fresh water, or for that matter, how well it can live in sea water. The presence of newborn individuals in the Hooghly River suggests that at least the young may be born in fresh water. The minute eyes of the Ganges shark, along with other Glyphis sharks, suggests that the entire group may be adapted to turbid water with poor visibility, as in large tropical rivers and muddy estuaries.
Type material:
Syntypes: A stuffed adult or late adolescent male about 1780 mm long in the Zoologisches Museum, Humboldt Universitat, Berlin apparently lost, and an alcohol-preserved specimen in the Museum National d'Histoire Naturelle, MNHN 1144, 564 mm long. Type Locality: "Im Ganges, 60 Stunden oberhalb des Meers bei Houghly gefangen".