Comparison of the longcomb sawfish (middle), largetooth sawfish (P. pristis; top) and knifetooth sawfish (Anoxypristis cuspidata; bottom). Notice especially the teeth on the saw, the shape of the tail and pectoral fins, and the position of the dorsal fin compared to the pelvic fins
The longcomb sawfish is possibly the largest species of sawfish, reaching a total length of up to 7.3m (24ft), but rarely more than 6m (20ft) today.[1][4] Its upperparts are greenish-brown to olive, while the underparts are whitish.[4][6][7]
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),[note 1] 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).[4][10] 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.[4][6] The smalltooth and longcomb sawfish might historically have come into contact in South Africa, but sawfish appear to have been extirpated from this country.[11][12]
The longcomb sawfish is native to tropical and subtropical waters in the western and central Indo-Pacific. Historically its distribution covered almost 5,900,000km2 (2,300,000sqmi) 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.[1][11] In Australia, it ranged from Shark Bay, along the northern part of the country, and south to Jervis Bay on the eastern coast.[5] Today it has disappeared from much of its historical range.[11] It can live in colder waters than its relatives, as also evidenced by the range in Australia where it occurs further south than the other species of sawfish.[4][13]
The longcomb sawfish is mainly found in coastal marine, mangrove and estuarine habitats, even in very shallow waters, but can also occur far offshore to a depth of more than 70m (230ft).[4][5] There are records from rivers far inland,[6] but it is not frequent in freshwater.[4][5] It is mainly found in places with a bottom consisting of sand, mud or silt.[5][6]
Behavior and life cycle
The longcomb sawfish feeds on fish, crustaceans and molluscs.[5] It thrashes its rostrum from side-to-side to dislodge prey from the seabed and to stun groups of fish.[6] All sawfish are harmless to humans, except when captured where they can cause serious injuries when defending themselves with their "saw".[6]
Little is known of its life cycle, but it is ovoviviparous and the young are 60–108cm (24–43in) long at birth.[6] It is often said that there are about 12 young in each litter,[1][4] but the basis for this number is unclear (in other sawfish species litter size ranges from 1 to 20).[11] The females give birth in inshore areas, and the young stay near the coast and in estuaries in the first part of their lives.[4][5] Sexual maturity is reached at an age of about 9 years,[5] and a length of 3.4–3.8m (11–12ft).[1] The maximum age is unknown, but it might be in excess of 50 years,[1] and an individual caught as a juvenile lived for 35 years at an aquarium.[5]
Conservation
The rostrum or "saw" of a longcomb sawfish (each red or black section on ruler is 10cm or 3.9in)
The longcomb sawfish has declined drastically and is listed by the IUCN as "Critically Endangered" in its Red List of Threatened Species.[1] The fins (for shark fin soup) and saw (as novelty items) are highly valuable, while some parts are used in Asian traditional medicine and the meat is eaten. Fishing is the main threat, but it is also threatened by habitat loss.[1][5] Because of the potential threat they (or rather their "saw") represent to humans, they are sometimes killed before being brought onto the boat when accidentally caught.[5] Because of the "saw", all sawfish are particularly prone to becoming entangled in fishing nets.[1]
Historically the longcomb sawfish has been recorded in 37 countries, but it has been extirpated from 2 and possibly extirpated from another 24, leaving only 11 countries where it certainly still survives.[11] In terms of area this means that it certainly survives in only 62% of its historical range.[11] The total population is believed to have declined by more than 80% over three generations.[1] The subpopulations in Australia are among the few that remain viable, but even they have declined,[1] and the species no longer occurs in New South Wales.[14] It receives a level of protection in Australia, Bahrain, Bangladesh, India, Indonesia, Malaysia, Qatar, South Africa (where already extirpated) and the United Arab Emirates,[11] but enforcement of fishing regulations are often lacking.[1] All sawfish species are listed on CITES Appendix I, which restricts international trade.[1]
Longcomb sawfish have few natural enemies, but can fall prey to large sharks and crocodiles.[6]
Small numbers are kept in public aquariums, with studbooks listing 13 individuals (7 males, 6 females) in North America in 2014, 6 individuals (3 males, 3 females) in Europe in 2013, and 2 individuals in Japan in 2017.[13]
Threats
The longcomb sawfish faces significant threats attributed to intense and poorly managed fishing pressure throughout its range. This pressure arises from both commercial and small-scale fisheries, including artisanal, cultural, and subsistence practices. Various fishing gears such as gillnets, trawls, and lines are utilized, with the distinctive toothed rostra of sawfish making them particularly vulnerable to entanglement, especially in gillnets and trawls. Over recent decades, fishing effort has escalated across the species' range, driven by escalating demand and exploitation in the fin and meat trade.[1]
The longcomb sawfish encounters high fishing pressure, resulting in poorly regulated and unmanaged exploitation. Bycatch in both commercial and small-scale fisheries, driven by escalating demand for fins and meat, poses a considerable threat. The species is frequently retained for these valuable parts, contributing to population decline. In some regions, measures such as the release of sawfishes by fishers may still lead to significant at-vessel and post-capture mortality, further impacting population viability.[1]
Critical habitats of the longcomb sawfish, including inshore freshwater, estuarine, mangrove, and coastal areas, are under threat due to habitat loss and degradation. The reduction of mangrove areas in Southeast Asia, for instance, is estimated to be around 30% since 1980. The most affected habitats are those crucial for nearshore and estuarine nursery activities. Additionally, potential impacts on adult longcomb sawfish associated with offshore oil and gas extraction, including activities like seismic surveys, further compound habitat threats in various regions.[1]
Historically, the northwest region of Australia provided relatively undisturbed coastal habitats for the longcomb sawfish. Presently, various factors pose substantial threats to the species in Western Australia, including coastal developments such as mining, natural resource operations, and oil and gas extraction. These developments introduce structures like lighted jetties, dredged shipping channels, and offloading structures, potentially hindering the movement of juvenile longcomb sawfish along the coastline. The increased prevalence of these structures may lead to population fragmentation or the destruction of vital juvenile habitats for the species.[1]
↑ Sawfish occasionally lose teeth during their life and these are not replaced.[8] Correct tooth count refers to actual teeth and alveoli ("tooth sockets") from lost teeth.[9]
Related Research Articles
A sawshark or saw shark is a member of a shark order bearing a unique long, saw-like rostrum edged with sharp teeth, which they use to slash and disable their prey. There are eight species within the Pristiophoriformes, including the longnose or common sawshark, shortnose sawshark, Japanese sawshark, Bahamas sawshark, sixgill sawshark, African dwarf sawshark, Lana's sawshark and the tropical sawshark.
Sawfish, 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 7–7.6 m (23–25 ft). They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes. All species are endangered.
The Bahamas sawshark, Pristiophorus schroederi, is a sawshark of the family Pristiophoridae, found in the western Central Atlantic Ocean from the Bahamas and Cuba at depths of between 400 and 1,000 m. These sharks are at least 80 cm long.
The smalltooth sand tiger or bumpytail ragged-tooth is a species of mackerel shark in the family Odontaspididae, with a patchy but worldwide distribution in tropical and warm temperate waters. They usually inhabit deepwater rocky habitats, though they are occasionally encountered in shallow water, and have been known to return to the same location year after year. This rare species is often mistaken for the much more common grey nurse shark, from which it can be distinguished by its first dorsal fin, which is larger than the second and placed further forward. It grows to at least 4.1 m (13.5 ft) in length. They have also been recently sighted in Irish and English waters.
The speartooth shark is a rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5 ft) long.
The longnose sawshark or common sawshark, is a sawshark of the family Pristiophoridae.
The narrow sawfish, also known as the pointed sawfish or knifetooth sawfish, is a species of sawfish in the family Pristidae, part of the Batoidea, a superorder of cartilaginous fish that include 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. 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 and are used for killing prey. It is found in the shallow coastal waters and estuaries of the Indo-West Pacific, ranging from 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 Pristis, Anoxypristis has a narrower rostral saw with numerous teeth on the distal part and no teeth on the basal one-quarter. It reaches a length of up to 3.5 m (11 ft).
The dwarf sawfish or Queensland sawfish, Pristis clavata, is a sawfish of the family Pristidae, found in tropical Australia. This endangered species is the smallest species in its family.
The largetooth sawfish is a species of sawfish in the family Pristidae. It is found worldwide in tropical and subtropical coastal regions, but also enters freshwater. It has declined drastically and is now critically endangered.
The smalltooth sawfish 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.
The mangrove whipray or whitetail stingray, is a species of stingray in the family Dasyatidae. It is widely distributed in the Indo-Pacific region from the Red Sea to northern Australia and Micronesia. A benthic inhabitant of shallow inshore waters, juvenile mangrove whiprays favor mangrove and estuarine habitats, while adults favor sandy to rocky areas in lagoons and coral reefs. This species can be identified by its thick, oval pectoral fin disc that is dark gray above with numerous white flecks, and by its relatively short, whip-like tail that is white past the stinging spine. It grows up to 1.4 m (4.6 ft) across.
Pristis is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and all species are considered critically endangered today.
Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, comprise the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.
The Memorandum of Understanding on the Conservation of Migratory Sharks is an international instrument for the conservation of migratory species of sharks. It was founded under the auspices of the Convention on the Conservation of Migratory Species of Wild Animals.
The Robinson River is a river in Australia's Northern Territory.
Atlanticopristis is an extinct genus of sclerorhynchid that lived during the Middle Cretaceous (Cenomanian) of what is now the Northeast Region of Brazil, between 100.5 and 93.9 million years ago. Fourteen fossil teeth from Atlanticopristis were found in the Alcântara Formation, and referred to the closely related Onchopristis in 2007; a redescription in 2008 by Brazilian paleontologists Manuel Medeiros and Agostinha Pereira assigned it to a new genus containing one species, Atlanticopristis equatorialis.
Archingeayia is an extinct genus of sawfish-like shark from the Cretaceous period. The name is derived from the type locale of the type species: Archingeay−Les Nouillers, France. This genus is known currently by isolated oral teeth alone from a singular species, A. sistaci. The specific epithet honors geologist Paul Sistac. This species was described from the lower Cenomanian of France.
↑ Allen, G. (1999). Marine Fishes of Tropical Australia and South East Asia (3rded.). Johns Hopkins University Press. pp.44–45. ISBN0-7309-8363-3.
↑ Slaughter, Bob H.; Springer, Stewart (1968). "Replacement of Rostral Teeth in Sawfishes and Sawsharks". Copeia. 1968 (3): 499–506. doi:10.2307/1442018. JSTOR1442018.
↑ Wueringer, B.E.; L. Squire Jr. & S.P. Collin (2009). "The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae)". Rev Fish Biol Fisheries. 19 (4): 445–464. doi:10.1007/s11160-009-9112-7. S2CID3352391.
1 2 White, S. & K. Duke (2017). Smith; Warmolts; Thoney; Hueter; Murray & Ezcurra (eds.). Husbandry of sawfishes. pp.75–85. ISBN978-0-86727-166-9.{{cite book}}: |work= ignored (help)
↑ Phillips, N. & Wueringer, B. (Autumn 2015). "Sawfish. Ancient predators in need of modern conservation tools". Wildlife Australia. Vol.52, no.1. pp.14–17. ISSN0043-5481.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
