Species Fact Profile: Largetooth Sawfish (Pristis pristis)

Largetooth Sawfish

Pristis pristis (Linnaeus, 1758)

Range: Widespread distribution with four main subpopulations – Eastern Atlantic, Western Atlantic, Eastern Pacific, and Indo-West Pacific Oceans

Habitat: Tropical and sub-tropical coastal waters worldwide.  Prefers shallow estuaries, usually less than 10 meters deep with mud, sand, or silt substrate.   Has been reported in freshwater as far as 1300 kilometers from the ocean, and some populations spend most – perhaps all – of their lives in freshwater.

Diet: Fish, Mollusks, Crustaceans

Social Grouping: Solitary

Reproduction: Sexually mature at about 7-10 years old with a length of 2.8-3 meters.  Breeding is seasonal, varying based on the region, with females breeding every 1-2 years.  Females return to their natal regions to give birth. 1-13 (average of 7) pups are born live (eggs are retained in the uterus and develop while being nourished by yolk sac), about 72-90 centimeters at birth.    Born in salt or brackish water at the mouths of rivers, then swim upstream to spend the first few years of their lives.

Lifespan: Unknown - Estimates 35-85 Years

Conservation Status: IUCN Critically Endangered, CITES Appendix I

• Capable of reaching lengths in excess of 6 meters (possibly up to 7.5 meters – largest confirmed was 7 meters in West Africa) and weigh 500-600 kilograms, though such sizes are rarely achieved anymore.   “Large” specimens encountered today are often 2-2.5 meters

• Shark-like body plan, though they are more closely related to rays.  Head is ventrally flattened, with the mouth and gills on the underside.  Capable of breathing while lying on the ocean floor by drawing water in through the spiracles, large holes behind their eyes.Pups are born with "covered" teeth on their saws, presumably to protect their mothers during the birthing process. 
• Most recognizable trait is the saw-like rostrum which represents 15-25% of the body length (proportionally longer in juveniles than in adults).   It has 14-24 teeth equally spaced on each side.  Females tend to have shorter saws with fewer teeth than males.  The teeth of the saw are set in cartilage and do not grow back if the root becomes damaged
• Dorsal coloration is yellowish-brown, often with a yellow tint on the fins.  The underside is gray or white.  Individuals in fresh water may have a more reddish hue caused by blood suffusion under their skin The teeth of the saw do not fully erupt and are covered with a sheath of tissue until after birth
• Hunt using their saw-like rostrum to stir up prey from the bottom of the waterways as well as to slash at fish.  No documented reports of targeting humans, though captured sawfish may defend themselves and inflict serious injuries
• Juveniles may be predated by large sharks and crocodilians
• Captive sawfish have demonstrated the ability to survive permanently in freshwater as well as salt.  They also have demonstrated the ability to jump as far as 5 meters out of the water and climb using their pectoral fins, possibly an adaptation for climbing waterfalls and rapids when traveling upstream
• The genus and species name are both derived from the Greek for “saw”
•  In serious decline, with extirpation likely to have occurred in the majority of countries where the species was found and all populations in decline, with many likely no longer sustainable.  Degree of legal protection varies across range
• Primary threat is overfishing.  The fins are used in shark fin soup, while the saws are collected for novelty items or for traditional medicinal believes (believed by some cultures to be useful for treating asthma if made into a tea).  Also hunted for meat and (historically) for oil in their livers.  The saw makes the fish especially vulnerable, as it becomes easily entangled in fishing nets
• Saws have been coveted throughout history, and have been found in Ancient Mayan tombs

      Zookeeper's Journal: Few if any marine fish are as bizarrely fascinating as the sawfishes.  The largetooth sawfish, biggest of the group, might be the most astonishing of all.  I remember being amazed by the sight of my first sawfish , and that was a specimen that “passes” as a big one these days.  To think of a sawfish that measures 7 meters – close to the length of the only whale sharks I’ve ever seen – with a saw longer than I am tall would be an amazing fish.  That such a creature has an appearance of nightmarish and yet is really so docile towards humans make it all the more incredible. I don’t know how much longer we can really expect to be seeing sawfish in aquariums.  The species is declining precipitously in the wild and aquariums have not had much luck in breeding the species – to date there has only been a single breeding success of a single sawfish species on the books.  I wonder if the specimens that we see in public aquariums are just too small to successfully breed.  To be frank, most of the set-ups I’ve seen this species in don’t really look like they are designed to manage these fish reproductively.  I wonder if what we would need is massive pools that could accommodate larger fish, with salinity being adjusted to replicate the changing environment of these animals through the seasons (although some populations do stay in freshwater for their entire lives).  If we as zoos and aquariums are going to develop a plan for breeding sawfish, we better come up with it quickly.  This species has already disappeared over most of its range and at this point its extinction – and that of the other sawfishes - seems almost inevitable.