Borneo Shark : Endangered Shark

Fish World | Borneo Shark : Endangered Shark | Borneo shark is extremely rare and known only by a few specimens. It lives in shallow coastal waters of the South Pacific Ocean. It is viviparous, meaning that it gives birth to live young. Like most sharks, the shark hunter of Borneo is a success and has few natural predators. Humans are an exception and the Borneo shark is currently threatened by fishing activities.

Borneo shark (Carcharhinus borneensis) is a very rare and little known requiem shark family Carcharhinidae, found in shallow coastal waters of northwest Borneo and perhaps elsewhere in Southeast Asia. A small shark reaching 70 cm (28 in.) long, this species is the only member of its genus with large pores over the corners of her mouth. It has a slender body, gray above and white below, and a long pointed snout. With only a handful of confirmed sightings and heavy fishing occurring in its range, the shark of Borneo has been assessed as endangered by the International Union for Conservation of Nature (IUCN).

Borneo shark was originally described as Carcharias (Prionodon) borneensis by Pieter Bleeker Dutch ichthyologist, in a 1858 issue of the journal Acta Societatis Scientiarum Indo-Regiae Neêrlandicae. He based his account on a 24 cm (9.4 inch) long immature male taken Singkawang, Borneo. Subsequent authors have recognized this as part of the shark Carcharhinus genre.
The evolutionary relationships of Borneo shark is uncertain. In 1988, Leonard Compagno placed him in an informal group that also contains phenetic smalltail shark (C. porosus), blackheads shark (C. sealei) spottail shark (C. sorrah), creek whaler ( C. fitzroyensis) whitecheek shark (C. dussumieri) hardnose shark (C. macloti) and Pondicherry shark (C. hemiodon). It also bears similarities Rhizoprionodon morphological species, although it clearly belongs to Carcharhinus.

All specimens from Borneo recent shark come only from the shallow coastal waters off northwest Borneo Mukah. Historically, its range may have been larger, with two known specimens of Kalimantan in the 1800s, one called the southern China in 1936, not confirmed by the Philippines and Java.
Borneo shark is thin-bodied, with a long pointed snout and oblique, narrow slit-shaped nostrils preceded the nipple-shaped patches of skin. The eyes are rather large and round, and equipped with nictitating membrane (third eye protection). The corners of the mouth size are short, indistinct furrows, and immediately above is a series of pores that are unique in the genre. There are 25-26 and 23-25 ​​upper rows of lower teeth. The upper teeth have a single narrow, oblique blade with serrated edges heavily, and cusplets high on the back side. The lower teeth are similar, but tend to be thinner and finely serrated. The five pairs of gill slits are short.

The pectoral fins are short, sharp and sickle (sickle-shaped), while the pelvic fins are small and triangular with a margin of almost right away. The first dorsal fin is rather large and triangular with a blunt tip gently to one margin sinuous flight, its origin is on the free ends behind the pectoral fins. The second dorsal fin is small and low, and comes over the middle of the base of the anal fin. There is no ridge between dorsal fins. The caudal fin is narrow, with a well developed lower lobe and a large ventral notch near the tip of the upper lobe. The dermal denticles are small and overlap, each with three horizontal ridges leading to marginal teeth. Borneo shark is slate gray above, darkening toward the tips of dorsal fins and upper lobe of the caudal fin, and white below. There are faint, light edges on the pectoral, pelvic and anal. The maximum size known is 70 cm (28 inches).

Virtually nothing is known about the natural history of sharks in Borneo. Like other members of his family, he is viviparous with fetal placental supported by a connection. A woman reported contained six puppies. Measuring newborns around 24-28 cm (9.4 to 11 in.) long, and males mature at less than 59 cm (23 in.) long, and females less than 61 cm (24 inches).

Until recently, only five confirmed shark specimens from Borneo have been known, all immature and collected before 1937. More thorough investigations in the region since failed to find it and the species was feared extinct, but in 2007 researchers at the Universiti Malaysia Sabah has rediscovered during a survey on fisheries resources of Sabah and Sarawak . Borneo shark is subject to heavy fishing pressure within its range, largely in demand from Asia for fins, and it remains at high risk of extinction. The International Union for Conservation of Nature (IUCN) has listed as Endangered.