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The term threatened strictly refers to these three categories (critically endangered, endangered and vulnerable), while vulnerable is used to refer to the least at risk of these categories. [3] The terms can be used somewhat interchangeably, as all vulnerable species are threatened, all endangered species are vulnerable and threatened, and all ...
The ISRA criteria take into account the complex biological and ecological needs of sharks. There are four criteria and seven sub-criteria. Important Shark and Ray Areas (ISRA) are discrete three-dimensional portions of habitat that are important for one or more species of chondrichthyans (sharks, rays and chimaeras) and have the potential to be managed for conservation. [1]
Despite these declines, comparatively few shark species are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which poses strict controls on the international trade in listed species. The first sharks to be included were basking and whale sharks in 2003, [11] and by 2016 a ...
The majority of shark nets used are gillnets, which is a wall of netting that hangs in the water and captures the targeted sharks by entanglement. [6] The nets may be as much as 186 metres (610 ft) long, set at a depth of 6 metres (20 ft), have a mesh size of 500 millimetres (20 in) and are designed to catch sharks longer than 2 metres (6.6 ft) in length.
This shark may host several species of parasites. For example, the blue shark is a definitive host of the tetraphyllidean tapeworm, Pelichnibothrium speciosum (Prionacestus bipartitus). It becomes infected by eating intermediate hosts, probably opah (Lampris guttatus) and/or longnose lancetfish (Alepisaurus ferox). [26]
The shark is among the 25 "most wanted lost" species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative. [2] The Pondicherry has been spotted in rivers in India in the late 2010s. [3] A Pondicherry shark was caught in the Menik Ganga (river) in SE Sri Lanka in 2011. It was photographed and released alive.
The use of sight probably varies with species and water conditions. The shark's field of vision can swap between monocular and stereoscopic at any time. [60] A micro-spectrophotometry study of 17 species of sharks found 10 had only rod photoreceptors and no cone cells in their retinas giving them good night vision while making them colorblind.
The Ganges shark (Glyphis gangeticus) is a critically endangered species of requiem shark found in the Ganges River (Padma River) and the Brahmaputra River of India and Bangladesh. It is often confused with the more common bull shark ( Carcharhinus leucas ), which also inhabits the Ganges River and is sometimes incorrectly referred to as the ...