snowtiger

here's something that i've known a bout for around 8 years, but thought i'd share with you....just remember if your on holiday and you fancy a dip in a river beware!

Conservation of River Sharks

River sharks are exceedingly rare. The Ganges Shark is known from only three museum specimens, all collected in the 19th Century. After an extensive search in the Ganges River over the past decade, a few additional specimens were caught in 1996. The species is regarded as critically endangered by the IUCN. The Speartooth Shark is known only from the stuffed holotype (original specimen), which was collected in the early 19th Century and now appears to be lost. Status of the Speartooth Shark is unknown, due to confusion with other Glyphis species from Borneo, New Guinea, and northern Australia. The validity of the Irrawaddy River Shark is in question, as it too, is known only from the original description and it is not known if the holotype is still in existence. It's status is likewise unknown. Glyphis species A is known from only a few specimens from rivers in northern Queensland and the Northern Territory of Australia. This species is regarded as critically endangered by Australia's Environment Protection and Biodiversity Act (EPBA) of 1999. Glyphis species B is known from a single small specimen collected in "Borneo" (no further location data is given), however several small specimens collected in the Kinabatangan River of Sabah, in northern Borneo, may be the same species. Its status is unknown. Glyphis species C is known from about 20 specimens from rivers in northern Queensland and the Northern Territory of Australia. This species is listed as endangered under Australia's EPBA.

River sharks may be particularly vulnerable to fishing pressure or habitat changes. Like other sharks, they probably feature a life history cycle characterized by long gestation, slow growth, delayed maturity, and small litter size. As such, their populations can be quickly devastated by even relatively low levels of exploitation, such as sport angling or gill netting. Like other sharks, Glyphis species probably exhibit a very slow rate of genetic change, making them unable to adapt to anthropogenic (human-caused) environmental changes. Humans living or working near tropical rivers or estuaries of the Austral-Asian region may degrade river shark habitat through pollution (sewage, detergents, rubbish, and run-off from agriculture, mining, or manufacturing processes) and so-called "management" (clearing mangrove swamps, redirecting water flow, building dams, etc.). These rivers and estuaries are absolutely vital to the continued survival of river sharks, which cannot readily colonize or adapt to new habitats. If much of their specialized habitat is ruined by human activity, these sharks will almost certainly become extinct.

River sharks are not always recognized for what they are: extremely rare, little known wildlife. So few specimens are available for study that the loss of even one is a great blow to scientific and conservation efforts. In 1986, a Glyphis was caught by an angler in fresh water about 60 km upstream the South Alligator River, in Australia's Northern Territory. Although the jaws were retained, this priceless specimen was eaten by the angler who caught it, resulting in the loss of much valuable data.

Here's hoping that, as more and more people become aware of them, the drive to protect and conserve river sharks -- and their habitats -- will grow. River sharks may not be particularly dangerous or flashy, but they are rare creatures that add to the diversity and mystery of our world.