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All sawfish species are near extinct – so if you see one… report it

Sawfishes are one of the most threatened families of marine fishes in the world. They were historically present throughout tropical and sub-tropical coastal waters of almost one hundred countries around the Atlantic and Indo-Pacific Oceans. But due to overfishing and habitat loss, global populations of every species of sawfish are estimated to have fallen to less than 10% of their historic levels. All sawfishes are currently listed as Critically Endangered worldwide by the International Union for the Conservation of Nature (IUCN). Unfortunately, the fins from the critically endangered sawfishes are highly favored in Asian markets. Though sawfishes are now protected under the highest protection level of the Convention on International Trade in Endangered Species (CITES), Appendix I, CITES protection will prevent sawfish fins from entering the trade. Their rostrum is also can reportedly fetch prices of over USD $1,000 apiece in some markets.

Green sawfish in the Shedd Aquarium, Chicago

The IUCN Shark Specialist Group is currently developing a Global Sawfish Conservation Strategy (for more info: http://www.iucnssg.org/index.php/sawfish) that will issue recommendations for meaningful research, education and conservation action and a roadmap for the development of regional conservation programmes to improve the status of sawfishes. If you have seen a sawfish, or want to join the network, please visit the site!

 

 

There are seven species of sawfish:

  • Anoxypristis cuspidata – knifetooth sawfish
  • Pristis clavata – Queensland sawfish
  • Pristis pectinata – smalltooth sawfish
  • Pristis zijsron – narrowsnout sawfish
  • Pristis microdon – Leichhardt’s sawfish or freshwater sawfish
  • Pristis perotteti – Largetooth sawfish
  • Pristis pristis – Common sawfish

The sawfish is not the same as a sawshark, though they are both cartilaginous fish. Sawfish and Sawsharks are actually only distantly related. The sawshark is indeed a shark, while the sawfish is a ray (see also our post on sawsharks: http://www.dutchsharksociety.org/ever-saw-a-sawshark/).

The number of ‘real’ species within the genus Pristis there is not certain. It is very difficult to obtain specimens or tissue samples from these increasingly rare species for taxonomic research. Pristis consists of four to six species, grouped by similar visual characteristics. The ‘Pristis pristis complex’; (Pristis pristis, P. microdon and P. perotteti), has relatively broad-based, strongly tapered and massive saws, with fewer (under 22) large teeth. P. microdon may not be distinct from the largetooth sawfish P. perotteti, which occurs in the Americas and west Africa. Further research is urgently needed. As many populations have already been extirpated their precise genetic identity may never be resolved.

Sawfish are nocturnal, usually sleeping during the day and hunting at night. They feed in shallow waters, where they search for squid, shrimps, small fish and crabs. Sawfish can reach lengths over 20 feet. The smalltooth sawfish might be small in teeth size, but not in length. According to NOAA, the maximum length of a smalltooth sawfish is 25 feet/8 meters. The green sawfish, that lives off Africa, Asia and Australia, can reach lengths of at least 24 feet.

Landed sawfish, Goa, India

It was always assumed that sawfish used their saws to probe sand or mud for prey. But preliminary experiments suggest that the fish’s long, tooth-lined saw are full of pores that can detect movements or electric fields of passing prey, also in murky and dark waters. Barbara Wueringer, a sensory neurobiologist at the Queensland University in Australia, has observed sawfish in captivity, and documented their behaviour. The saw is a cartilaginous extension of the skull and can also be used as a weapon. You can see a sawfish use its saw in this clip, made by Barbara:

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