The smalltooth sawfish (Pristis pectinata) is a species of sawfish in the family Pristidae. It is found in shallow tropical and subtropical waters in coastal and estuarine parts of the Atlantic. Reports from elsewhere are now believed to be misidentifications of other species of sawfish. It is a critically endangered species that has disappeared from much of its historical range.
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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OvoviviparousOvoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous an...
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starts withThe smalltooth sawfish reputedly reaches a total length of up to 7.6 m (25 ft), but this is likely an exaggeration and the largest confirmed size is 5.54 m (18.2 ft). It weighs up to 350 kg (770 lb).
Its upperparts are brownish-gray, gray, bluish-gray or blackish, and the underparts are whitish.
Unlike the largetooth sawfish (P. pristis), the only other sawfish in the Atlantic, the smalltooth sawfish has a leading edge of the dorsal fin that is placed roughly above the leading edge of the pelvic fins (when the sawfish is seen from above or the side), relatively short pectoral fins and lack of a distinct lower lobe to the tail (lower lobe very small or absent). It can be separated from the more similar dwarf sawfish (P. clavata) and green sawfish (P. zijsron) by the distribution (both are only found in the Indo-Pacific) and the dorsal fin (its leading edge is placed slightly or clearly behind the leading edge of the pelvic fins in the dwarf and green sawfish). The smalltooth sawfish has a relatively narrow rostrum ("saw") with 20–32 teeth on each side.
The smalltooth sawfish is found in tropical and subtropical parts of the Atlantic, including the Caribbean and Gulf of Mexico. Its original range was the smallest of the sawfish species, covering about 2,100,000 km2 (810,000 sq mi). In the west it once ranged from the United States to Uruguay and in the east from Senegal to Angola. Today it has disappeared from much of its historical range. There are old reports from the Mediterranean Sea, but this likely involved vagrants and according to the FAO the species can be considered locally extinct in the Mediterranean Sea.
Smalltooth sawfish are mostly found in coastal marine and estuarine brackish waters. It prefers water less than 8 m (26 ft) deep, but adults are occasionally seen offshore at depths of up to 122 m (400 ft). During periods with increased salinity, juveniles have been seen far up rivers. This species is mostly found in places with soft bottoms such as mud or sand, but may also occur over hard rocky bottoms or at coral reefs. They are often found in areas with mangrove or seagrass. The lower water temperature limit is 16–18 °C (61–64 °F).
The reproductive behavior of smalltooth sawfish has not been well studied, despite their classification as a critically endangered species. Nevertheless, much can be inferred based on information known about the reproductive behavior of other elasmobranchs. Observations show that smalltooth sawfish may participate in precopulatory behavior in captivity. Much of this activity involves the biting of pectoral fins known as "courtship biting." There is sexual dimorphism in the teeth of smalltooth sawfish, with males presenting a higher mean value for both left and right rostral tooth counts. The electrosensory system is believed to be used in the courtship behavior of sawfish and other elasmobranchs. Reproductively active males use the sensory organs in their saw to locate females and vice versa. Once a mate has been selected, several copulations occur during which the male inserts his claspers, which are paired intromittent organs, into the female's vagina. The claspers contain subdermal siphon sacs that provide the propulsive power for sperm transfer. It is also possible that the siphon sacs assist with sawfish sperm competition by washing away rival sperm from the female's vagina before copulations.
Smalltooth sawfish have recently been observed, for the first time, to reproduce parthenogenetically in the wild. About 3 percent of the sawfish living in a Florida estuary are the result of parthenogenesis. The research team speculates that since smalltooth sawfish are so rare, females might sometimes fail to find a male during the mating season, inducing the parthenogenetic process.
Elasmobranchs are ovoviviparous, have relatively long gestation periods, and internal fertilization. The sawfish eggs hatch in the uterus and the young continue to grow without a placental connection to the mother. The fetal sawfish receives nourishment from a yolk sac and absorbs all the nutrients it can from the yolk before it is born. Litters have been reported of up to 20 pups and the reproductive cycle is believed to be every two years. After sex, mating pairs separate without forming a pair bond and each continues polygamous matings.
Smalltooth sawfish are extremely vulnerable to overexploitation because of their propensity for entanglement in nets, their restricted habitat, and low rate of population growth. The species is listed as critically endangered by the IUCN Red List. The Pristis pectinata species is critically endangered mainly because of the fishing pressure business which feeds into the shark-fin industry. Historically it was found in 47 countries, but it has been possibly extirpated from 26 countries and its presence is uncertain in a further 16 countries, leaving only 5 countries where it certainly still survives, although the IUCN lists it as surviving in 9 countries. In terms of area, the authors of the former estimate, Dulvy et al., believe it certainly survives in only 19% of its historical range. It is the only sawfish that certainly still survives in the United States (the largetooth sawfish, P. pristis, has likely been extirpated from this country), and it has been listed by the National Marine Fisheries Service as endangered under the Endangered Species Act since 2003. It is estimated that the smalltooth sawfish population in the United States now equals less than 5% of the historical population in this country. In the United States it once occurred from Texas to New York (northern range as summer visitors), but today it is essentially limited to Florida. In the Everglades region of Florida the population is now stable and possibly slowly rising. Other countries where it certainly survives are the Bahamas, Cuba, Belize, Honduras and Sierra Leone, but whether it survives in the Western Gulf of Mexico or off the Atlantic coast of South America is unclear. The species is listed on Appendix I of the Convention on International Trade in Endangered Species.
Small numbers are maintained in public aquariums in North America with studbooks listing 12 individuals (5 males, 7 females) in 2014. The only kept elsewhere are at a public aquarium in Colombia. It is the only species of sawfish that has been bred in captivity.
