Sawfish, also known as carpenter sharks, are a family of very large batoidea characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse plane teeth, arranged in a way that resembles a saw. They are among the largest fish, with some species reaching lengths of about .
They are found worldwide in tropical and subtropical regions in coastal Seawater and brackish estuarine waters, as well as freshwater rivers and lakes. All species are critically endangered.They should not be confused with (order Pristiophoriformes) or the extinct sclerorhynchoids (order Rajiformes) which have a similar appearance, or swordfish (family Xiphiidae) which have a similar name but a very different appearance.
Sawfishes are relatively slow breeders and the females give birth to live young. They feed on fish and invertebrates that are detected and captured with the use of their saw. They are generally harmless to humans, but can inflict serious injuries with the saw when captured and defending themselves.
Sawfish have been known and hunted for thousands of years, and play an important mythological and spiritual role in many societies around the world.
Once common, sawfish have experienced a drastic decline in recent decades, and the only remaining strongholds are in Northern Australia and Florida, United States. All five species are rated as Critically Endangered by the International Union for Conservation of Nature (IUCN). They are hunted for their fins (shark fin soup), use of parts as traditional medicine, their teeth and saw. They also face habitat loss. Sawfish have been listed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since 2007, restricting international trade in them and their parts. They are protected in Australia, the United States and several other countries, meaning that sawfish caught by accident have to be released and violations can be punished with hefty fines.
Despite their appearance, sawfish are Batoidea (superorder Batoidea). The sawfish family has traditionally been considered the sole living member of the order Pristiformes, but recent authorities have generally subsumed it into Rhinopristiformes, an order that now includes the sawfish family, as well as families containing guitarfish, wedgefish, Trygonorrhinidae and the like. Sawfish quite resemble guitarfish, except that the latter group lacks a saw, and their common ancestor likely was similar to guitarfish.
Anoxypristis contains a single living species that historically was included in Pristis, but the two genera are morphologically and genetically highly distinct. Today Pristis contains four living, valid species divided into two Species complex. Three species are in the smalltooth group, and there is only a single in the largetooth group. Three poorly defined species were formerly recognized in the largetooth group, but in 2013 it was shown that P. pristis, P. microdon and P. perotteti do not differ in morphology or genetics. As a consequence, recent authorities treat P. microdon and P. perotteti as of P. pristis.
Pristis pectinata Latham, 1794 | Smalltooth sawfish | Critically endangered | Atlantic | Marine waters, estuaries | |
Pristis zijsron Pieter Bleeker, 1851 | Green sawfish, longcomb sawfish, narrowsnout sawfish, olive sawfish | Critically endangered | Indo-Pacific | Marine waters, estuaries | |
The extinct order Sclerorhynchoidei had long rostra with large denticles similar to sawfishes and Sawshark. This feature was convergently evolved, recently proposed as 'pristification', and their closest living relatives are actually skates. While they are often called "sawfishes", the more accurate common name for sclerorhynchoids is "sawskates".
Sawfish have two relatively high and distinct , wing-like pectoral and , and a tail with a distinct upper lobe and a variably sized lower lobe (lower lobe relatively large in Anoxypristis; small to absent in Pristis sawfish). The position of the first dorsal fin compared to the pelvic fins varies and is a useful feature for separating some of the species. There are no .
Like other , sawfish lack a swim bladder (instead controlling their buoyancy with a large oil-rich liver), and have a skeleton consisting of cartilage. Males have , a pair of elongated structures used for mating and positioned on the underside at the pelvic fins. The claspers are small and indistinct in young males.
Their contain an internal partition shaped like a corkscrew, called a spiral valve, which increases the surface area available for food absorption.
The two remaining species, the dwarf sawfish and narrow sawfish, are considerably smaller, but are still large fish with a maximum total length of at least and respectively.
Historically they ranged in the East Atlantic from Morocco to South Africa,
and in the West Atlantic from New York (United States) to Uruguay, including the Caribbean Sea and Gulf of Mexico. There are old reports (last in the late 1950s or shortly after) from the Mediterranean and these have typically been regarded as vagrants, but a review of records strongly suggests that this sea had a breeding population. In the East Pacific they ranged from Mazatlán (Mexico) to northern Peru. Although the Gulf of California occasionally has been included in their range, the only known Pacific Mexican records of sawfish are from south of its mouth. They were widespread in the western and central Indo-Pacific, ranging from South Africa to the Red Sea and Persian Gulf, east and north to Korea and southern Japan, through Southeast Asia to Papua New Guinea and Australia. Today sawfish have disappeared from much of their historical range.
Sawfish are mostly found in relatively shallow waters, typically at depths less than , and occasionally less than . Young prefer very shallow places and are often found in water only deep. Sawfish can occur offshore, but are rare deeper than . An unidentified sawfish (either a largetooth or smalltooth sawfish) was captured off Central America at a depth in excess of .
The dwarf and largetooth sawfish are strictly warm-water species that generally live in waters that are and respectively. The green and smalltooth sawfish also occur in colder waters, in the latter down to , as illustrated by their (original) distributions that ranged further north and south of the strictly warm-water species. Sawfish are bottom-dwellers, but in captivity it has been noted that at least the largetooth and green sawfish readily take food from the water surface. Sawfish are mostly found in places with soft bottoms such as mud or sand, but may also occur over hard rocky bottoms or at . They are often found in areas with seagrass or mangrove.
are typically found much deeper, often at depths in excess of , and when shallower mostly in colder subtropical or temperate waters than sawfish.
Mating involves the male inserting a clasper, organs at the pelvic fins, into the female to fertilize the eggs. As known from many elasmobranchs, the mating appears to be rough, with the sawfish often sustaining lacerations from its partner's saw. However, through genetic testing it has been shown that at least the smalltooth sawfish also can reproduce by parthenogenesis where no male is involved and the offspring are cloning of their mother. In Florida, United States, it appears that about 3% of the smalltooth sawfish offspring are the result of parthenogenesis. It is speculated that this may be in response to being unable to find a partner, allowing the females to reproduce anyway.
The pregnancy lasts several months. There are 1–23 young in each sawfish litter, which are long at birth. In the the rostrum is flexible and it only hardens shortly before birth. To protect the mother the saws of the young have a soft cover, which falls off shortly after birth.
The pupping grounds are in coastal and estuarine waters. In most species the young generally stay there for the first part of their lives, occasionally moving upriver when there is an increase in salinity. The exception is the largetooth sawfish where the young move upriver into freshwater where they stay for 3–5 years, sometimes as much as from the sea. In at least the smalltooth sawfish the young show a degree of site fidelity, generally staying in the same fairly small area in the first part of their lives. In the green and dwarf sawfish there are indications that both sexes remain in the same overall region throughout their lives with little mixing between the subpopulations. In the largetooth sawfish the males appear to move more freely between the subpopulations, while mothers Natal homing to give birth to their own young.The length of the full lifespan of sawfish is labeled with considerable uncertainty. A green sawfish caught as a juvenile lived for 35 years in captivity, and a smalltooth sawfish lived for more than 42 years in captivity. In the narrow sawfish it has been estimated that the lifespan is about 9 years, and in the Pristis sawfish it has been estimated that it varies from about 30 to more than 50 years depending on the exact species.
Exactly how they use their saw after the prey has been located has been debated, and some scholarship on the subject has been based on speculations rather than real observations. In 2012 it was shown that there are three primary techniques, informally called "saw in water", "saw on substrate" and "pin". If a prey item such as a fish is located in the open water, the sawfish uses the first method, making a rapid swipe at the prey with its saw to incapacitate it. It is then brought to the seabed and eaten. The "saw on substrate" is similar, but used on prey at the seabed. The saw is highly streamlined and when swiped it causes very little water movement. The final method involves pinning the prey against the seabed with the underside of the saw, in a manner similar to that seen in guitarfish. The "pin" is also used to manipulate the position of the prey, allowing fish to be swallowed head-first and thus without engaging any possible fin spines. The spines of catfish, a common prey, have been found imbedded in the rostrum of sawfish. Schools of mullets have been observed trying to escape sawfish. Prey fish are typically swallowed whole and not cut into small pieces with the saw, although on occasion one may be split in half during capture by the slashing motion. Prey choice is therefore limited by the size of the mouth. A sawfish had a catfish in its stomach.
It had been suggested that sawfish use their saw to dig/rake in the bottom for prey, but this was not observed during a 2012 study, or supported by later hydrodynamic studies. Large sawfish often have rostral teeth with tips that are notably worn.
Sawfish were occasionally mentioned in antiquity, in works such as Pliny's Natural History (77–79 AD). Pristis, the scientific name formalised for sawfish by Linnaeus in 1758, was also in use as a name even before his publication. For example, sawfish or " priste" were included in Libri de piscibus marinis in quibus verae piscium effigies expressae sunt by Guillaume Rondelet in 1554, and " pristi" were included in De piscibus libri V, et De cetis lib. vnus by Ulisse Aldrovandi in 1613. Outside Europe, sawfish are mentioned in old Greater Iran texts, such as 13th century writings by Zakariya al-Qazwini.
Sawfish have been found among archaeological remains in several parts of the world, including the Persian Gulf region, the Pacific coast of Panama, coastal Brazil and elsewhere.
The cultural significance of sawfish varies significantly. The , in what is currently Mexico, often included depictions of sawfish rostra (saws), notably as the striker/sword of the monster Cipactli.
Numerous sawfish rostra have been found buried at the Templo Mayor, and two locations in coastal Veracruz had Aztec names referring to sawfish. In the same general region, sawfish teeth have been found in Mayan graves. The sawfish saw is part of the dancing masks of the Huave people and Zapotec peoples in Oaxaca, Mexico. The Guna people on the Caribbean coast of Panama and Colombia consider sawfish as rescuers of drowning people, and protectors against dangerous sea creatures. Also in Panama, sawfish were recognized as containing powerful spirits that could protect humans against supernatural enemies.In the Bissagos Islands off West Africa, dancing dressed as sawfish and other sea creatures is part of men's coming-of-age ceremonies. In Gambia, the saws indicate courage; the more saws are on display in a house, the more courageous the owner is seen to be. In Senegal, the Lebu people believe the saw can protect their family, house and livestock. In the same general region, they are recognized as ancestral spirits who use the saw as a magic weapon. The Akan people of Ghana see sawfish as an authority symbol. There are with sawfish in the African language Duala language.
In Asia, sawfish are a powerful symbol in many cultures. Asian shamans use sawfish rostrums for exorcisms and other ceremonies to repel demons and disease.Raloff, Janet (2007). Hammered Saws , Science News vol. 172, pp. 90–92. They are believed to protect houses from ghosts when hung over doorways. Illustrations of sawfish are often found at Buddhist temples in Thailand. In the Sepik region of New Guinea, locals admire sawfish, but also see them as punishers, who will unleash heavy rainstorms on anyone breaking fishing taboos. Among the Warnindhilyagwa, a group of Indigenous Australians, the ancestral sawfish, Yukwurrirrindangwa and rays created the land. The ancestral sawfish carved out the river of Groote Eylandt with their saws. Among European sailors, sawfish were often feared as animals that could sink ships by piercing/sawing the hull with their saw (claims now known to be entirely untrue), but there are also stories of them saving people. In one case, it was described how a ship almost sank during a storm in Italy in 1573. The sailors prayed and made it safely ashore, where they discovered a sawfish that had "plugged" a hole in the ship with its saw. A sawfish rostrum said to be from this miraculous event is kept at the sanctuary of Carmine Maggiore in Naples.
Sawfish have been used as symbols in recent history. During World War II, illustrations of sawfish were placed on navy ships, and used as symbols by both American and Nazi German submarines. Sawfish served as the emblem of the German U-96 submarine, known for its portrayal in Das Boot, and was later the symbol of the 9th U-boat Flotilla. The German World War II Kampfabzeichen der Kleinkampfverbände (Battle Badge of Small Combat Units) depicted a sawfish.
In cartoons and humorous popular culture, the sawfish—particularly its rostrum ("nose")—has been employed as a sort of living tool. Examples of this can be found in Vicke Viking and Fighting Fantasy volume "Demons of the Deep".
A stylized sawfish was chosen by the Central Bank of the West African States to appear on coins and banknotes of the CFA franc currency. This was due to it being a mythological representation of fecundity and prosperity. The image takes its form from an Akan people and Baoule bronze weight, used for exchanges in the trade of gold powder.
Among the five sawfish species, only the four Pristis species are known to be kept in public aquariums. The most common is the largetooth sawfish, with including 16 individuals in North America in 2014, 5 individuals in Europe in 2013 and 13 individuals in Australia in 2017; this was followed by the green sawfish, with 13 individuals in North America, and 6 in Europe. Both of these species are also kept at public aquariums in Asia, and the only captive dwarf sawfish are in Japan. In 2014, studbooks included 12 smalltooth sawfish in North America, and the only ones kept elsewhere are at a public aquarium in Colombia.
Sawfish fishing goes back several thousand years, but until relatively recently it typically involved traditional low-intensity methods such as simple hook-and-line or Spearfishing. In most regions the major population decline in sawfish started in the 1960s–1980s. This coincided with a major growth in demand of fins for shark fin soup, the expansion of the international shark finning fishing fleet, and a proliferation of modern nylon fishing nets. The exception is the dwarf sawfish which was relatively widespread in the Indo-Pacific, but by the early 1900s it had already disappeared from most of its range, only surviving for certain in Australia (there is a single recent possible record from the Arabian region). The saw has been described as sawfish's Achilles' heel, as it easily becomes entangled in fishing nets. Sawfish can also be difficult or dangerous to release from nets, meaning that some fishers will kill them even before bringing them aboard the boat, or cut off the saw to keep it/release the fish. Because it is their main hunting device, the long-term survival of saw-less sawfish is highly questionable. In Australia where sawfish have to be released if caught, the narrow sawfish has the highest mortality rate, but it is still almost 50% for dwarf sawfish caught in . In an attempt of lowering this, a guide to sawfish release has been published.
Endangered sawfish and other fish in Florida are showing strange behaviors and dying because of environmental toxins. These toxins, produced by microalgae near the sea bottom, affect the neurological systems of fish.
Largetooth sawfish have been monitored in Fitzroy River, Western Australia, a primary stronghold for the species, since 2000. In December 2018, the largest recorded mass fish death in the river occurred when more than 40 sawfish died, mainly because of heat and a severe lack of rainfall during a poor wet season. A 14-day research expedition in Far North Queensland in October 2019 did not spot a single sawfish. Expert Dr Peter Kyne of Charles Darwin University said that habitat change in the south and gillnet fishing in the north had contributed to the decline in numbers, but now that fishers had started working with the conservationists, and water diversions to the river flows had become a bigger problem in the north. Also, impact of successful saltwater crocodile conservation is a negative one on sawfish populations. However, there were still good populations in the Adelaide River and Daly River in the Northern Territory, and the Fitzroy River in the Kimberley.
A study by Murdoch University researchers and Indigenous rangers, which captured more than 500 sawfish between 2002 and 2018, concluded that the survival of the sawfish could be at risk from dams or major water diversions on the Fitzroy River. It found that the fish are completely reliant on the Kimberley's wet season floods to complete their breeding cycle; in recent drier years, the population has suffered. There has been debate about using water from the river for agriculture and to grow fodder crops for cattle in the region.
Sharks and Rays Australia (SARA) are conducting a citizen science investigation to understand the sawfish's historical habitats. Citizen can report their sawfish sighting online.
The status of the two species of the Atlantic region, the smalltooth and largetooth sawfish, is comparable to the Indo-Pacific. For example, sawfish have been entirely extirpated from most of the Atlantic coast of Africa (only survives for certain in Guinea-Bissau and Sierra Leone), as well as South Africa. The only relatively large remaining population of the largetooth sawfish in the Atlantic region is at the Amazon estuary in Brazil, but there are smaller in Central America and West Africa, and this species is also found in the Pacific and Indian Oceans. The smalltooth sawfish is only found in the Atlantic region and it is possibly the most threatened of all the species, as it had the smallest original range (range ) and has experienced the greatest contraction (disappeared from c. 81% of its original range). It only survives for certain in six countries, and it is possible that the only remaining viable population is in the United States. In the United States the smalltooth sawfish once occurred from Texas to New York, but its numbers have declined by at least 95% and today it is essentially restricted to Florida. However, the Florida population retains a high genetic diversity, has now stabilised and appears to be slowly increasing. A Recovery Plan for the smalltooth sawfish has been in effect since 2002. It has been strictly protected in the United States since 2003 when it was added to the Endangered Species Act as the first marine fish. This makes it "illegal to harm, harass, hook, or net sawfish in any way, except with a permit or in a permitted fishery". The fine is up to US$10,000 for the first violation alone. If accidentally caught, the sawfish has to be released as carefully as possible and a basic how-to guide has been published. In 2003 an attempt of adding the largetooth sawfish to the Endangered Species Act was denied, in part because this species does not occur in the United States anymore (last confirmed US record in 1961). However, it was added in 2011, and all the remaining sawfish species were added in 2014, restricting trade in them and their parts in the United States. In 2020, a Florida fisherman used a power saw to remove a smalltooth sawfish's rostrum and then released the maimed fish; he received a fine, community service and probation.
Since 2007, all sawfish species have been listed on CITES Appendix I, which prohibits international trade in them and their parts. The only exception was the relatively robust Australian population of the largetooth sawfish that was listed on CITES Appendix II, which allowed trade to public aquariums only. Following reviews Australia did not use this option after 2011 and in 2013 it too was moved to Appendix I. In addition to Australia and the United States, sawfish are protected in the European Union, Mexico, Nicaragua, Costa Rica, Ecuador, Brazil, Indonesia, Malaysia, Bangladesh, India, Pakistan, Bahrain, Qatar, the United Arab Emirates, Guinea, Senegal and South Africa, but they are likely already functionally extirpated or entirely extirpated from several of these countries. Illegal fishing continues and in many countries enforcement of fishing laws is lacking. Even in Australia where relatively well-protected, people are occasionally caught illegally trying to sell sawfish parts, especially the saw. The saw is distinctive, but it can be difficult to identify flesh or fins as originating from sawfish when cut up for sale at . This can be resolved with DNA testing. If protected their relatively low reproduction rates make these animals especially slow to recover from overfishing. An example of this is the largetooth sawfish in Lake Nicaragua where once abundant. The population rapidly crashed during the 1970s when tens of thousands were caught. It was protected by the Nicaraguan government in the early 1980s, but remains rare today. Nevertheless, there are indications that at least the smalltooth sawfish population may be able to recover at a faster pace than formerly believed, if well-protected. Uniquely in this family, the narrow sawfish has a relatively fast reproduction rate (generation length about 4.6 years, less than one-third the time of the other species), it has experienced the smallest contraction of its range (30%) and it is one of only two species considered Endangered rather than Critically Endangered by the IUCN. The other rated as Endangered is the dwarf sawfish, but this primarily reflects that its main decline happened at least 100 years ago and IUCN ratings are based on the time period of the last three generations (estimated about 49 years in dwarf sawfish).
There are several research projects aimed at sawfish in Australia and North America, but also a few in other continents. The Florida Museum of Natural History maintains the International Sawfish Encounter Database where people worldwide are encouraged to report any sawfish encounters, whether it was living or a rostrum seen for sale in a shop/online. Its data is used by biologists and conservationists for evaluating the habitat, range and abundance of sawfish around the world. In an attempt of increasing the knowledge of their plight the first "Sawfish Day" was held on 17 October 2017, and this was repeated on the same date in 2018.
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