Instruct: Given a question, retrieve relevant passages that answer the question.
Query: Where do sawfishes live?
Sawfishes, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish with some species reaching lengths of about 7–7.6m (23–25ft).[2] They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes.[3]
Sawfish are popular in public aquariums, but require very large tanks. In a review of 10 North American and European public aquariums that kept sawfish, their tanks were all very large and ranged from about 1,500,000to 24,200,000l (400,000–6,390,000USgal).[54] Individuals in public aquariums often function as "ambassadors" for sawfish and their conservation plight.[88][89] In captivity they are quite robust, appear to grow faster than their wild counterparts (perhaps due to consistent access to food) and individuals have lived for decades, but breeding them have proven difficult.[54] In 2012, four smalltooth sawfish pups were born at Atlantis Paradise Island in the Bahamas and this remains the only time a member of this family has been successfully bred in captivity[54][87] (unsuccessful breeding attempts had happened earlier at the same facility, including a miscarriage in 2003).[90] Nevertheless, it is hoped that this success may be the first step in a captive breeding program for the threatened sawfish.[4] It is speculated that seasonal variations in water temperature, salinity and photoperiod are necessary to encourage breeding.[54] Artificial insemination, as already has been done in a few captive sharks, is also being considered.[91] Tracking studies indicate that if sawfish are released to the wild after spending a period in captivity (for example, if they outgrow their exhibit), they rapidly adopt a movement pattern similar to that of fully wild sawfish.[92]
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.
The dwarf and largetooth sawfish are strictly warm-water species that generally live in waters that are 25–32°C (77–90°F) and 24–32°C (75–90°F) respectively.[50][54] The green and smalltooth sawfish also occur in colder waters, in the latter down to 16–18°C (61–64°F), as illustrated by their (original) distributions that ranged further north and south of the strictly warm-water species.[54][59] 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.[54] Sawfish are mostly found in places with soft bottoms such as mud or sand, but may also occur over hard rocky bottoms or at coral reefs.[60] They are often found in areas with seagrass or mangrove.[3]
A combination of characters are necessary to distinguish it from the other sawfish species: the longcomb sawfish has teeth to near the base of the rostrum or "saw" (unlike the knifetooth sawfish, "Anoxypristis cuspidata"), 23–37 teeth on each side of the rostrum (18–24 in the dwarf sawfish, "P. clavata", 20–32 in smalltooth sawfish, "P. pectinata", and 14–24 in largetooth sawfish, "P. pristis"), the teeth towards the tip of the rostrum are clearly closer to each other than those at its base (unlike the dwarf, smalltooth and largetooth sawfish where either equally spaced or only marginally closer to each other towards the tip of the rostrum), a relatively narrow rostrum, width equalling 9–17% of its length (typically wider in dwarf and largetooth sawfish), a rostrum that is 23–33% of the total length of the fish (20–25% in dwarf sawfish), relatively short pectoral fins (unlike the knifetooth and largetooth sawfish), a leading edge of the dorsal fin that is located clearly behind the leading edge of the pelvic fins (in front of in largetooth sawfish and roughly above in smalltooth sawfish) and it has a very small or no lower tail lobe (present in knifetooth and largetooth sawfish). It can be further separated from the two most similar species, the dwarf and smalltooth sawfish, by the considerably smaller maximum size of the former species, and the less greenish colour (when alive/recently dead) and essentially Atlantic distribution of the latter species. The smalltooth and longcomb sawfish might historically have come into contact in South Africa, but sawfish appear to have been extirpated from this country.
Adults are primarily found in estuaries and marine waters to a depth of , but mostly less than . Nevertheless, the species does appear to have a greater affinity for freshwater habitats than the smalltooth sawfish ("P. pectinata"), green sawfish ("P. zijsron"), and dwarf sawfish ("P. clavata"). Largetooth sawfish from the population in Lake Nicaragua appear to spend most, if not all, of their life in freshwater, but tagging surveys indicate that at least some do move between this lake and the sea. Captive studies show that this euryhaline species can thrive long-term in both salt and freshwater, regardless of its age, and that an acclimation from salt to freshwater is faster than the opposite. In captivity they are known to be agile (even swimming backwards), have an unusual ability to "climb" with the use of the pectoral fins and they can jump far out of the water; a individual jumped to a height of . It has been suggested that this may be adaptions for traversing medium-sized waterfalls and rapids when moving upriver. They are generally found in areas with a bottom consisting of sand, mud or silt. The preferred water temperature is between , and or colder is lethal.
The longcomb sawfish is native to tropical and subtropical waters in the western and central Indo-Pacific. Historically its distribution covered almost and it ranged from South Africa, north to the Red Sea and Persian Gulf, east to the South China Sea, through Southeast Asia to Australia. In Australia, it ranged from Shark Bay, along the northern part of the country, and south to Jervis Bay on the eastern coast. Today it has disappeared from much of its historical range. It can live in colder waters than its relatives, as also evident by the range in Australia where it occurs further south than the other species of sawfish.
The pregnancy lasts several months.[33] There are 1–23 young in each sawfish litter, which are 60–90cm (2–3ft) long at birth.[3][33] In the embryos the rostrum is flexible and it only hardens shortly before birth.[33] To protect the mother the saws of the young have a soft cover, which falls off shortly after birth.[64][65] 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.[50][55][56][66] The exception is the largetooth sawfish where the young move upriver into freshwater where they stay for 3–5 years, sometimes as much as 400km (250mi) from the sea.[58] 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.[67] 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 return to the region where they were born to give birth to their own young.[68][69]
Relatively little is known about the reproductive habits of the sawfish, but all species are ovoviviparous with the adults females giving birth to live young once a year or every second year.[3] In general, males appear to reach sexual maturity at a slightly younger age and smaller size than females.[3] As far as known, sexual maturity is reached at an age of 7–12 years in Pristis and 2–3 years in Anoxypristis. In the smalltooth and green sawfish this equals a total length of 3.7–4.15m (12.1–13.6ft), in the largetooth sawfish at 2.8–3m (9.2–9.8ft), in the dwarf sawfish about 2.55–2.6m (8.4–8.5ft), and in the narrow sawfish at 2–2.25m (6.6–7.4ft).[3] This means that the generation length is about 4.6 years in the narrow sawfish and 14.6–17.2 years in the remaining species.[3]
The cultural significance of sawfish varies significantly. The Aztecs in what is currently Mexico often included depictions of sawfish rostra (saws), notably as the striker/sword of the monster Cipactli.[80] Numerous sawfish rostra have been found buried at the Templo Mayor and two locations in coastal Veracruz had Aztec names referring to sawfish.[4] In the same general region, sawfish teeth have been found in Mayan graves.[81] The saw of sawfish is part of the dancing masks of the Huave and Zapotecs in Oaxaca, Mexico.[4][82] The Kuna people on the Caribbean coast of Panama and Colombia considers sawfish as rescuers of drowning people and protectors against dangerous sea creatures.[8] Also in Panama sawfish were recognized as containing powerful spirits that could protect humans against supernatural enemies.[8]
In addition to the living sawfish, there are several extinct species that only are known from fossil remains. The oldest known is the monotypic genus Peyeria where the remains are about 100 million years old from the Cenomanian age (Late Cretaceous),[1] though it may represent a rhinid rather than a sawfish.[27] Indisputable sawfish genera emerged in the Cenozoic age about 60 million years ago, relatively soon after the Cretaceous–Paleogene mass extinction. Among these are Propristis, a monotypic genus only known from fossil remains, as well as several extinct Pristis species and several extinct Anoxypristis species (both of these genera are also represented by living species).[1][28] Historically, palaeontologists have not separated Anoxypristis from Pristis.[1] In contrast, several additional extinct genera are occasionally listed, including Dalpiazia, Onchopristis, Oxypristis,[29] and Mesopristis,[28] but recent authorities generally include the first two in the family Sclerorhynchidae and the last two are synonyms of Anoxypristis.[1][30] Fossils of sawfish have been found around the world in all continents.[29]
The knifetooth sawfish ("Anoxypristis cuspidata"), also known as the pointed sawfish or narrow sawfish, is a species of sawfish in the family Pristidae, part of the Batoidea, a superorder of cartilaginous fish that includes the rays and skates. Sawfish display a circumglobal distribution in warm marine and freshwater habitats. Their extant biodiversity is limited to five species belonging to two genera (Pristis and Anoxypristis). The sawfishes are characterised by the long, narrow, flattened rostrum or extension on their snout. This is lined with sharp transverse teeth, arranged in a way that resembles the teeth of a saw. It is found in the shallow coastal waters and estuaries of the Indo-West Pacific, ranging from the Red Sea and the Persian Gulf to southern Japan, Papua New Guinea and northern Australia. It is the only living member of the genus Anoxypristis, but was previously included in the genus "Pristis". Compared to that genus, "Anoxypristis" has a narrower rostral saw with numerous teeth on the distal part and no teeth on the basal one-quarter (toothless section about one-sixth in juveniles). This endangered species reaches a length of up to .
The largetooth sawfish is a predator that feeds on fish, molluscs and crustaceans. The "saw" can be used both to stir up the bottom to find prey and to slash at groups of fish. Sawfish are docile and harmless to humans, except when captured where they can inflict serious injuries when defending themselves with the "saw".
The only remaining stronghold of the four species in the Indo-Pacific region (narrow, dwarf, largetooth and green sawfish) is in Northern Australia, but they have also experienced a declined there.[4][69] Pristis sawfish are protected in Australia and only Indigenous Australians can legally catch them.[100][103] Violations can result in a fine of up to AU$121,900.[13] The narrow sawfish does not receive the same level of protection as the Pristis sawfish.[100][104] Under CITES regulations, Australia was the only country that could export wild-caught sawfish for the aquarium trade from 2007 to 2013 (no country afterwards).[21] This strictly involved the largetooth sawfish where the Australian population remains relatively robust, and only living individuals "to appropriate and acceptable aquaria for primarily conservation purposes".[21] Numbers traded were very low (eight between 2007 and 2011),[4] and following a review Australia did not export any after 2011.[21] Except for Australia, sawfish have been extirpated or only survive in very low numbers in the Indo-Pacific region. For example, among the four species only two (narrow and largetooth sawfish) certainly survive in South Asia, and only two (narrow and green sawfish) certainly survive in Southeast Asia.[3]
Sawfish fishing goes back several thousand years,[7] but until relatively recently it typically involved traditional low-intensity methods such as simple hook-and-line or spearing. In most regions the major population decline in sawfish started in the 1960s–1980s.[7][83][95] This coincided with a major growth in demand of fins for shark fin soup, the expansion of the international shark finning fishing fleet,[83] and a proliferation of modern nylon fishing nets.[95] 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).[3][96] The saw has been described as sawfish's Achilles' heel, as it easily becomes entangled in fishing nets.[97] 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,[55] 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.[98] In Australia where sawfish have to be released if caught, the narrow sawfish has the highest mortality rate,[66] but it is still almost 50% for dwarf sawfish caught in gill nets.[96] In an attempt of lowering this, a guide to sawfish release has been published.[99]
Since 2007, all sawfish species have been listed on CITES Appendix I, which prohibits international trade in them and their parts.[11][12][112] 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.[11] Following reviews Australia did not use this option after 2011 and in 2013 it too was moved to Appendix I.[21] In addition to Australia and the United States, sawfish are protected in the European Union, Mexico, Nicaragua, 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.[3][7][113] Illegal fishing continues and in many countries enforcement of fishing laws is lacking.[3][21] Even in Australia where relatively well-protected, people are occasionally caught illegally trying to sell sawfish parts, especially the saw.[13] The saw is distinctive, but it can be difficult to identify flesh or fins as originating from sawfish when cut up for sale at fish markets. This can be resolved with DNA testing.[114] If protected their relatively low reproduction rates make these animals especially slow to recover from overfishing.[85] 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.[4] 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.[115] 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.[3] 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).[3][96]
In the Bissagos Islands off West Africa dancing dressed as sawfish and other sea creatures is part of men's coming-of-age ceremonies.[80][83] In Gambia the saws indicate courage; the more on display at a house the more courageous the owner.[83] 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 with the saw as a magic weapon. The Akan people of Ghana see sawfish as an authority symbol. There are proverbs with sawfish in the African language Duala.[84] In some other parts of coastal Africa, sawfish are considered extremely dangerous and supernatural, but their powers can be used by humans as their saw retains the powers against disease, bad luck and evil.[84] Among most African groups consumption of meat from sawfish is entirely acceptable, but in a few (in West Africa the Fula, Serer and Wolof people) it is taboo.[83] In Asia sawfish are a powerful symbol in many cultures. Asian shamans use sawfish rostrums for exorcisms and in other ceremonies to repel demons and disease.[85] They are believed to protect houses from ghosts when hung over doorways.[4] Illustrations of sawfish are often found at Buddhist temples in Thailand.[81] In the Sepik region of New Guinea locals admire sawfish, but also see them as punishers that will unleash heavy rainstorms on anyone breaking fishing taboos.[8] 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 saw.[8][86] Among European sailors sawfish were often feared as animals that could sink ships by piercing/sawing in the hull with their saw (claims now known to be entirely untrue),[59] 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.[4]
The rostrum (saw) plays a significant role in both locating the prey and capturing it, which is unique among jawed fish.[72][73] The head and rostrum contain thousands of sensory organs, the ampullae of Lorenzini, that allow the sawfish to detect and monitor the movements of other organisms by measuring the electric fields they emit.[74] Electroreception is also known from some other families of fish. In sawfish the sensory organs are packed most densely on the upper- and underside of the rostrum, although with minor differences in their position and numbers depending on exact species.[74] Those on the upperside allow sawfish to create an image of the three-dimensional area above it, even in waters of low visibility.[72] Utilizing their saw as an extended sensing device, sawfish are able to "view" their entire surroundings by maintaining a position low to the seafloor.[1] It appears that sawfish can detect potential prey items through electroreception from a distance of about 40cm (16in).[5] Some waters where sawfish live are very murky, limiting the possibility of hunting by sight.[69]
Harranahynchus is an extinct genus of sclerorhynchid (Family Sclerorhynchidae) sawfish from the late Maastrichtian deposits of the Muwaqqar Chalk Marl Formation of Harrana in Jordan. The genus is so far represented by a single species, "Harranahynchus minutadens" and named after its minute rostral and dental battery teeth that do not exceed two millimeters in length, a size that is significantly smaller than the rostral teeth of any other modern or extinct sawfish species. Harranahynchids were medium-sized benthic predators around 2-2.5 meters in length and lived in the shallow offshore subtropical marine waters of the southern Tethys Ocean alongside other sclerohynchid sawfishes such as "Schizorhiza stromeri" Weiler, 1930.
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,[54] and a smalltooth sawfish lived for more than 42 years in captivity.[70] 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.[3]
The longcomb sawfish, narrowsnout sawfish or green sawfish ("Pristis zijsron") is a species of sawfish in the family Pristidae, found in tropical and subtropical waters of the Indo-West Pacific. It has declined drastically and is now considered a critically endangered species.
The most distinctive feature of sawfish is their saw-like rostrum with a row of whitish teeth (rostral teeth) on either side of it. The rostrum is an extension of the chondrocranium ("skull"),[27] made of cartilage and covered in skin.[33] The rostrum length is typically about one-quarter to one-third of the total length of the fish,[5] but it varies depending on species, and sometimes with age and sex.[1] The rostral teeth are not teeth in the traditional sense, but heavily modified dermal denticles.[34] The rostral teeth grow in size throughout the life of the sawfish and a tooth is not replaced if it is lost.[34][35] In Pristis sawfish the teeth are found along the entire length of the rostrum, but in adult Anoxypristis there are no teeth on the basal one-quarter of the rostrum (about one-sixth in juvenile Anoxypristis).[36][37] The number of teeth varies depending on the species and can range from 14 to 37 on each side of the rostrum.[2][38][note 1] It is common for a sawfish to have slightly different tooth counts on each side of its rostrum (difference typically does not surpass three).[39][40] In some species, females on average have fewer teeth than males.[1][39] Each tooth is peg-like in Pristis sawfish, and flattened and broadly triangular in Anoxypristis.[2] A combination of features, including fins and rostrum, are typically used to separate the species,[2][38] but it is possible to do it by the rostrum alone.[41]
The longcomb sawfish feeds on fish, crustaceans and molluscs. It thrashes its rostrum from side-to-side to dislodge prey from the seabed and to stun groups of fish. All sawfish are harmless to humans, except when captured where they can cause serious injuries when defending themselves with their "saw".
The Bahamas sawsharks ("Pristiophorus schroeder") have very little information on them. Studies are being done daily to learn more about the deep sea dweller. They are located near Cuba, Florida, and the Bahamas (hence their name) where they dwell in the depths of 400–1000 m. As far as their appearance they can be identified by their snouts with teeth which appear as a saw, as well as their length, they are averaged at 80 cm in length.
Saw sharks and sawfish are cartilaginous fish possessing large saws. These are the only two fish that have a long blade-like snout. Although they are similar in appearances, saw sharks are distinct from sawfish. Sawfish are not sharks, but a type of ray. The gill slits of the sawfishes are positioned on the underside like a ray, but the gill slits of the saw shark are positioned on the side like a shark. Sawfish can have a much larger size, lack barbels, and have evenly sized teeth rather than alternating teeth of the saw shark. Clear difference is that a sawfish has no barbels and a saw shark has a prominent pair halfway along the saw. The saw shark uses these like other bottom fish, as a kind of antennae, feeling the way along the ocean bottom until it finds some prey of interest. Both the saw shark and the sawfish utilize the electroreceptors on the saw, ampullae of Lorenzini, to detect the electric field given off by buried prey.
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.