Sawfish: The Super Senser

spermwhale_INFOG
Art by Dana Rose Salonoy

Download the sawfish module and the full size minigraphics.

Introduction

  • Genus: Pristidae spp.
  • Despite their fearsome appearance, they do not attack people unless provoked or surprised.
  • The bladed snout can be used by the sawfish to catch prey by swinging it back and forth to stun or cut fish and dig bottom sediments to search for food.
  • All species considered endangered or critically endangered by the International Union for Conservation of Nature (IUCN).

Distribution

Sawfishes are widely distributed across tropical and warm temperate nearshore waters in the Atlantic and Indo-Pacific. They are found in coastal waters such as lagoons, estuaries, and brackish river deltas. Some species can penetrate rivers and large lakes. These fishes tend to prefer shallow, muddy, brackish water, spending most of their time on or near the seabed.

They were once abundant from the 19th century to the early part of the 20th century but today, the different sawfish species have a fragmented population and in some areas are considered to be locally extinct.  Sawfish prefer shallow, coastal waters and even swim into freshwater river systems. There are no formal studies done on the size of the global sawfish population; data is mostly dependent on fish landing data and personal anecdotes from fishing communities which show that the once abundant sawfish is now an increasingly rare sight all over the world.

Sawfishes are known to be present in all Southeast Asian countries in the Coral Triangle, namely Indonesia, Malaysia, and the Philippines (CT3) although they are increasingly becoming very rare. The largetooth sawfish were once considered common in the Philippines but none have been recorded in recent surveys.

Why they are important

Sawfishes are among the top predators in the shallow coastal environment. They help keep the lagoon and estuarine ecosystems healthy by regulating populations of prey species, as they weed out the sick, old, and weak members of their prey.

 

Biology

Like sharks, sawfishes lack a swim bladder and use a large, oil-filled liver to control their buoyancy. Their skeleton is made of cartilage. Because they prefer to live in muddy habitats, their eyes are underdeveloped and their rostrum serves are their main sensory device

Not much is known about the reproductive habits of the sawfish other than they have a slow reproductive rate. They reach sexual maturity at around 10 years old and produce only a few young after they mate which makes their population slow to recover. Females are ovoviviparous, bearing live young or pups, whose rostral blades are soft and flexible during embryonic development, with teeth that are enclosed by a sheath – so as to protect the mother during the birthing process.

“Sawfish” by Simon Fraser University licensed under CC-BY 2.0
“Sawfish” by Simon Fraser University (CC-BY 2.0)

Threats

Overfishing is one of the biggest threats to the sawfish due to their slow reproductive cycle. They are primarily fished for their fins and rostrum; the demand for the meat is not as big. The meat is often only locally sold compared to the bile, liver, and rostrum which are traded internationally for traditional medicine. Sawfish fins are highly sought after for making shark fin soup and can fetch up to $4,000 USD for one set. Their rostrum are sold as curios or souvenirs in some cultures. Also, the loss of mangrove forests and other nursery habitats contributes to the decline of sawfish populations.

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” “The saw of a sawfish” on display at Bedford Museum (CC0 1.0) 

The sawfish’s rostrum makes it especially vulnerable to bycatch because it can get easily tangled in nets, the teeth on the rostrum can easily grab the net and they will often drown because sawfish need to continuously swim in order to breath.

What you can do

Avoid using nets in rivers or estuaries. These environments are the preferred habitats of the sawfish and their sword-like rostrum makes it very easy for them to get tangled and drown.

Don’t buy sawfish products. These include souvenir rostrums and traditional medicine that uses sawfish liver, skin, oil, and bile. Do not patronize restaurants that serve shark fin soup which can use sawfish fins and those of protected shark species. Sawfish products are banned from international trade.

Spread awareness about their struggle. Share this article and other sawfish related information amongst your friends and let them know that we must protect this species!

Laws that protect Sawfish in the CT3

Quiz

The sawfish are most famous for their rostrum, the saw-like nose. How do the sawfish use their rostrum?

Answer by commenting on the Facebook post by CTI-Southeast Asia!

Download the Protected Philippine Aquatic Wildlife posters.

See the full contest details here.

Article by Panji Brotoisworo. Art by Dana Rose Salonoy.

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2 thoughts on “Sawfish: The Super Senser

    1. Hi, Bejay! Thanks for your comment! you’re right in saying that the rostrum is the sawfish’s main sensory device. To enter the contest you must (1) like the facebook post and (2) comment your answer on the original facebook post. The full contest mechanics are here: http://bit.ly/1Wuxw0h Thanks!

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