Sawfish

Legislative protection

Environment Protection and Biodiversity Conservation Act 1999

In Australia, up to five species of sawfish are found and three of these, the freshwater sawfish, green sawfish and the dwarf/Queensland sawfish, are currently listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

A combined recovery plan for the listed sawfish and the two species of freshwater shark (Glyphis glyphis and Glyphis garricki) is currently being developed.

Species listed under the EPBC Act:

Listed below are the five species found in Australia

Dwarf/Queensland sawfish (Pristis clavata) - listed as Vulnerable under the EPBC Act

  • Occurs from Cairns (Queensland) to the Kimberly Coast (Western Australia). Can be found in coastal and estuarine habitats, as well as the mudflats in the Gulf of Carpentaria. Can be found some distance up rivers, almost into freshwater.
  • Grows to at least 1.4 metres
  • EPBC Act Status and Documents - Pristis clavata - Dwarf Sawfish, Queensland Sawfish

Freshwater sawfish (Pristis microdon) - listed as Vulnerable under the EPBC Act

  • Occurs mostly in fresh or brackish rivers in northern Australia, sometimes more than 100 kilometres inland. Is not normally found in the sea off Australia.
  • Grows to at least 2.8 metres
  • Biggest freshwater fish in Australia
  • EPBC Act Status and Documents - Pristis microdon - Freshwater Sawfish

Green sawfish (Pristis zijron) - listed as Vulnerable under the EPBC Act

These species are not listed under the EPBC Act:

Narrow/Knifetooth sawfish (Anoxypristis cuspidata)

  • Occurs in northern Australian waters, and is mostly marine. Can be found at depths of at least 40 metres
  • Grows to a length of about 3.5 metres
  • Global population is considered to be less than 50% of its level 30-50 years ago.

Wide/Smalltooth sawfish (Pristis pectinata)

  • The current records of its distribution need confirmation. It is mostly marine and rarely enters rivers.
  • Grows to at least 7.6 metres, and is the largest of the sawfish.

Sawfish are threatened by a number of activities. They are hunted for their fins, flesh and other body parts, which are used in traditional medicines, or sold as souvenirs and there have also been occasions when they have been collected for live animal displays. Other than habitat loss, the greatest threat to sawfish is entanglement in fishing nets as their snout is easily caught up in nets. Sawfish have the added trouble of being caught in marine trawling nets and they have also occasionally been found tangled in shark nets off the Queensland coast.

The species-specific monitoring of all sawfishes taken by any fishing methods in Australian waters is essential for the accurate assessment of their current distributions, biological, behavioural and ecological characteristics, as well as threats to their habitats and their survival.

Habitat and biology

Location

Sawfish are commonly found in estuaries and freshwater rivers and creeks in Queensland, the Northern Territory and Western Australia. They move between fresh and salt water easily, but are quite happy to sit on the bottom of shallow muddy rivers.

Biology

The most obvious part of a sawfish is its 'saw'. This is actually called the rostrum, or snout. The 'teeth' on the snout are in fact modified scales and not real teeth. Their teeth are found in their mouth, which is located on the underside of the sawfish, along with its nostrils and gill slits; much like the members of the ray family. They mainly feed on crabs, shrimps and other bottom dwelling invertebrates, first they crush their food and then swallow it whole.

Whilst their eyesight is reasonable they rely on their highly sensitive snout for detecting the heartbeat and movement of buried prey. It is also used to lash out at fast moving prey and immobilise them and although they are generally quiet animals, when threatened the saw also serves as a weapon.

Not a great deal is known about the reproductive biology of the sawfish. It is believed that they mate every other year and that the average litter size is about eight pups. Size at birth varies, depending on species. The pups are born live, and therefore have a protective gel-like covering over their soft saws, to prevent injury to the mother. As their saw hardens, the covering dissolves and they start to hunt small prey.

Resources