Green sawfish  (Pristis zijsron)

The green sawfish is a ray, with a shark-like body and a striking elongated snout, known as a saw. This saw bears 23-37 pairs of teeth and earns the species its common name (4) (5). This sawfish is greenish brown or olive in colour, with pale white to yellowish underparts (5) (6). At maturity, males reach impressive lengths of up to 430 cm. Female lengths are not known, but it is thought that they reach similar sizes as males (2).

This once common sawfish has a wide distribution in the northern Indian Ocean, reaching east to South Africa, and is also found off Indonesia and Australia (1) (3) as well as in the western Pacific (7). Throughout this range, the populations of this species have been severely depleted and sightings have been rare in the last 40 years (1).

This species inhabits muddy or sandy bottom habitats in inshore marine areas, intertidal areas and the lower parts of rivers (1) (6) (3). It can be found in lagoons, estuaries and shallow bays (6).

This species often rests on the bottom with the saw held upwards at an angle (6). It feeds on slow-moving fish that form shoals, including mullet, which are tackled by swiping at them with the side of the saw; they may also remove crustaceans and molluscs from the sediment by using the saw to rake them out (4).

Like other sharks and rays, fertilisation is internal and females give birth to live young (4). At birth, the saws have a gelatinous coating which protects the mother (3).

The main threat facing this species is accidental ‘by-catch' by prawn fisheries, fish trawling, gillnetting and other fishing activities (4). Due to the saw and their large size, this species becomes entangled in nets very easily; as they are difficult to set free, they rarely survive becoming caught in this way (4). Direct fishing has also been a problem; this sawfish has been widely caught for its fins for use in the shark fin soup industry, its saw and for its flesh (4). The high price of the fins in Asian markets increase the threats facing all members of this family (3). Furthermore, degradation of the soft-bottomed habitats upon which they depend has been widespread (4).

This species is classified as Critically Endangered on the IUCN Red List of Threatened Species (1). Current recovery actions include carrying out further research into the distribution and ecology of this sawfish, and encouraging its protection (4). It has been proposed that an Australian national recovery team should be established in order to set up and coordinate the recovery programme for this and other threatened sawfish (3).

For more on this species see the Fishbase species account:
http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=7956&genusname=Pristis&speciesname=zijsron

For more on sawfish see:
http://hometown.aol.com/nokogiri/

For more information on sharks and their conservation see Project Aware:
http://www.projectaware.org/

Authenticated by Dr Colin Simpfendorfer, Centre for Shark Research, Mote Marine Laboratory:
http://www.mote.org/~colins/ColinsWebPage.htm and Matthew McDavitt:
http://hometown.aol.com/nokogiri