largetooth sawfish

Taxonomy:

Phylum– Chordata

Class– Chondrichthyles

Subclass– Elasmobranchii

Super Order– Batoidea

Order– Rhinopristiformes

Common Name– Rays

Family– Pristidae

Common Name– Sawfish

Genus– Pristis

Species– pristis

Status: IUCN Red List CRITICALLY ENDANGERED

Average Size and Length: The Largetooth sawfish may reach up to 25 feet. So far, the largest recorded Largetooth sawfish was 23 feet and from West Africa. Most Largetooth sawfish today are between 6.6 and 8.2 feet in length.

Average Weight: Larger Largetooth sawfish may way between 1,102-1,323 pounds and some research suggests they could weigh even more.

Teeth and Jaw: The oral teeth of the Largetooth sawfish are curved with anteriorly obtuse cutting edges. The teeth are large. Much larger than the teeth of the Smalltooth sawfish. There are about 12 functional rows in each jaw. As the Largetooth sawfish gets older, so do the number of teeth. Largetooth sawfish pups are born with 70 teeth, but could possibly be born with between 80-90 depending on its size.

Head: The rostrum of the Largetooth sawfish has a width that is 15%–25% of its length, which is relatively wide compared to the other sawfish species. There are 14–24 equally separated teeth on each side of the rostrum. On average, females have shorter rostrums with fewer teeth than males. It is important to note that the proportional rostrum length also varies with age, with average being around 27% of the total length, but can be as high as 30% in juveniles and as low as 20%–22% in adults.

Denticles: The dermal denticles of the Largetooth sawfish are widely spread. The blades are ovoid in shape and rather strongly oblique. The bases are roughly four-cornered and are evident through the skin in very young specimens but more concealed in larger specimens (Deynat, 2005).

Tail: There is a long lower tail lobe.

Demographic, Distribution, Habitat, Environment and Range: The Largetooth sawfish can be found worldwide in tropical and subtropical coastal regions, but it also enters freshwater and has been recorded in rivers as far as 830 miles from the ocean.

Adult Largetooth sawfish are found in estuaries and in marine waters to a depth of about 82 feet, but typically around 33 feet. They do seem to visit freshwater habitats more often than the other species of sawfish. The population in Lake Nicaragua spend almost all of their life in freshwater. They are generally found in areas with a bottom consisting of sand, mud or silt. They prefer water temperatures between 75–90 °F. Temperatures colder than 66 °F will kill them.

The historical range of the Largetooth sawfish was much wider than what it is today. Historically, its East Atlantic range was from Mauritania to Angola. Research suggests that there is a breeding population in the Mediterranean, or that there used to be in the past. Its West Atlantic range was from Uruguay to the Caribbean and the Gulf of Mexico. Studies suggest that the Texas reports are true, but the Florida reports are false, and those are another species. Its East Pacific range was from Peru to Mazatlán in Mexico. The Largetooth sawfish was widespread in the Indo-Pacific, ranging from South Africa to the Horn of Africa, India, Southeast Asia and Northern Australia. Its total distribution covered almost 2,800,000 square miles, more than any other species of sawfish.

Check out this interactive map courtesy of the Florida Museum, a University of Florida accredited resource. 

Diet: The Largetooth sawfish feeds on fish, mollusks and crustaceans.

Largetooth sawfish, especially young, are sometimes eaten by crocodiles and large sharks.

Aesthetic Identification: The Largetooth sawfish is grey to yellowish-brown on the upper-side with a yellow hint on the fins. The Largetooth sawfish that spend most of their time in freshwater have a reddish color that is caused by blood suffusion below the skin. Underneath, they are counter-shaded greyish to white. The dorsal fin of the Largetooth sawfish is in a forward position. The leading edge is in front of the leading edge of the pelvic fins. It has long pectoral fins with angular tips.

Biology and Reproduction: The Largetooth sawfish is ovoviviparous. Sexual maturity is reached at a length of about 9.2–9.8 feet, 7–10 years old. They breed seasonal, but the exact timing varies and is dependent on location. The adult females can breed once every 1–2 years, the gestation period is about five months. There are suggestions that mothers return to the region where they were born to give birth to their own young. There are 1–13 young in each litter, with an average of 7. They are 28–35 inches long at birth. They are likely born in salt or brackish water near river mouths, but move into freshwater where the young spend the first 3–5 years of their life. They are found sometimes as much as 250 miles upriver, and even further in the Amazon basin (corresponds with larger juveniles). Occasionally, young individuals become isolated in freshwater pools during floods and may live there for years.

The potential lifespan of the Largetooth sawfish is unknown. There are many estimations, none proven. These estimations range from 30 to 35 to 45 to 80 years.

Behavioral Traits, Sensing and Intelligence: The saw can be used both to stir up the bottom to find prey and to slash at groups of fish.

Speed: In captivity they are known to be agile. They can swim backwards. They even have an unusual ability to “climb” with the use of the pectoral fins and they can jump far out of the water, one up to 16 feet. Possibly an upriver movement adaptation.

Largetooth Sawfish Future and Conservation: The Largetooth sawfish was once abundant, but now critically endangered. The main threat is overfishing, but it also suffers from habitat loss. Both their fins and saws are highly valued. Their fins are used in shark fin soup and their saws as novelty items. The meat is used as food. Their saws are prone to becoming tangled in fishing nets. Historically, sawfish were also killed for the oil in their liver. Sawfish are protected in Australia and the United States where a number of conservation projects have been initiated, but probably too late here in the United States. The Largetooth sawfish has been extirpated from many regions where formerly present. All sawfish species are restricted from international trade. The Largetooth sawfish receives a level of protection in Bangladesh, Brazil, Guinea, India, Indonesia, Malaysia, Mexico, Nicaragua, Senegal and South Africa, but illegal fishing continues, enforcement of fishing laws is often absent, and it has already disappeared from some of these countries.

Sawfishes may also fall victim to red tide. Red tides (Karenia brevis) occur in the Gulf of Mexico, also along the Florida coast (now extending to the Atlantic east Florida coast) and impact many species of fish and wildlife.

The Largetooth sawfish is the most frequent sawfish in public aquariums. It is often listed under the synonym P. microdon. There are 16 individuals (10 males, 6 females) in North American aquariums in 2014, 5 individuals (3 males, 2 females) in European aquariums in 2013, and 13 individuals (6 males, 7 females) in Australian aquariums in 2017. Asia has some too.

Largetooth Sawfish Recorded Attacks on Humans: Not a threat to humans. However, if threatened or captured, it will defend itself with its saw, which can cause serious injury.