Introduction:
Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish with some species reaching lengths of about 7–7.6 m (23–25 ft).They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes. All species are endangered.
Sawfishes are relatively slow breeders and the females give birth to live young themselves.They feed on fish and invertebrates that are detected and captured with the use of their saw. They are generally harmless to humans, but can inflict serious injuries with the saw when captured and defending themselves.
Sawfish diversity varies considerably among Ocean regions. Two species are present in the Atlantic, four in the Indo-West Pacific, and one Species is present in the eastern Pacific. Only the Largetooth Sawfish is present in all oceans.
How many species of sawfish are there?
There are only five species of sawfish, which are found throughout the world in tropical and subtropical waters, but Florida and northern Australia appear to be the last strongholds for these species.
Largetooth (freshwater) sawfish Pristis pristis
· Circumtropical (occurs in tropical and subtropical waters throughout the world).
· The largetooth sawfish lives in rivers for years as juveniles and moves out to the ocean as it matures.
Smalltooth sawfish P. pecinata
· Occurs in Atlantic Ocean.
· Last stronghold for the species is southern Florida, USA.
Green sawfish P. zijsron
· Occurs in Indo-West Pacific.
· One of the largest species of sawfish.
Dwarf sawfish P. calvata
· Occurs in the Indo-West Pacific, but most commonly in northern Australia.
· One of the two small species of sawfish, the dwarf sawfish still grows over 3 m (9.8 ft) in length.
Narrow sawfish Anoxypristis cuspidata
· Occurs in the Indo-West Pacific.
The only species to not have rostral teeth on the lower (i.e. near the head) quarter of its saw.
Culturally important
Sawfishes have been revered for millennia By societies along the tropical and subtropical Coasts of the Atlantic and Indo-Pacific Oceans. They were first used on coins 5,000 years ago, And are still found on modern West Africa Currency. Today, art, folklore, and mythology Are almost all that is left to remind us of how Widespread and abundant sawfishes once were.
Formerly widespread and abundant
Sawfishes were once common throughout the tropical and subtropical waters of the Atlantic, Indian, and Pacific Oceans; they are thought to have been present in the waters of more than 90 countries. Over the past century, the populations of all five species have declined dramatically around the world, to the point where they can now only be reliably found in two remaining strongholds (where they are strictly protected): Florida, U.S. and Northern Australia at regional scales there is considerable uncertainty in status because of poor scientific capacity as well as a paucity of scientific survey effort. Some local populations are thought to be already extinct, with most others on the brink of extinction.
An exceptionally threatened family of fishes
Given the dramatic declines experienced by all sawfish species and their much-reduced geographic range, sawfishes are among the most threatened family of marine fishes. Three species are assessed as Critically Endangered and two species listed as Endangered on the IUCN Red List of Threatened Species™.
The previous (2006) assessment categorized all sawfishes as Critically Endangered. On the surface our reassessments could be interpreted as an improvement in status for the Narrow sawfish (Anoxypristis cuspidata) and Green sawfish (P. zijsron) since 2006. We caution, however, this is not a genuine improvement in their status. Our knowledge on the status of these species has improved over the intervening period and we now have a better understanding of their declines. Notwithstanding the non-genuine change in status, these species are still at great risk, especially so because their populations continue to decline unhalted.
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By : Nikita Joshi
2nd year
Bsc(H) Chemistry
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