Тісті балықтар: Сипаттамасы және қорғау шаралары

Family of fishes

Automatic taxobox
| name = Sawfish
| fossil range = fossil range|99.7|0|Late Cretaceous Recent|ref= 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. They should not be confused with sawsharks (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 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. The five species are rated as Endangered or Critically Endangered by the 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. 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.

Sawfish have a strong shark like body, a flat underside and a flat head. Pristis sawfish have a rough sandpaper like skin texture because of the covering of dermal denticles, but in Anoxypristis the skin is largely smooth. and somewhat resemble a cobblestone road. They have small eyes and behind each is a spiracle, which is used to draw water past the gills. The gill slits, five on each side, are placed on the underside of the body near the base of the pectoral fins. Unlike sawfish, sawsharks also have a pair of long barbels on the rostrum ("saw"). Males have claspers, a pair of elongated structures used for mating and positioned on the underside at the pelvic fins. or possibly even more. Old unconfirmed and highly questionable reports of much larger individuals do exist, including one that reputedly had a length of , another that had a weight of , and a third that was long and weighed In the past it was often reported that the dwarf sawfish only reaches about , but this is now known to be incorrect.

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 In captivity they are quite robust, appear to grow faster than their wild counterparts (perhaps due to consistent access to food). Some individuals have lived for decades, but breeding them has proven difficult. Nevertheless, it is hoped that this success may be the first step in a captive breeding program for the threatened sawfish. 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. 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 studbooks 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. In 2014, studbooks included 12 smalltooth sawfish in North America, locally even abundant, As traditional medicine (especially Chinese medicine, but also known from Mexico, Brazil, Kenya, Eritrea, Yemen, Iran, India and Bangladesh) sawfish parts, oil or powder have been claimed to work against respiratory ailments, eye problems, rheumatism, pain, inflammation, scabies, skin ulcers, diarrhea and stomach problems, but there is no evidence supporting any of these uses. and as recent as the 1920s in Florida it was regarded as the best fish oil for consumption. 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, In Australia where sawfish have to be released if caught, the narrow sawfish has the highest mortality rate,

Although fishing is the main cause of the drastic decline in sawfish, another serious problem is habitat destruction. Coastal and estuarine habitats, including mangrove and seagrass meadows, are often degraded by human developments and pollution, and these are important habitats for sawfish, especially their young. In a study of juvenile sawfish in Western Australia's Fitzroy River about 60% had bite marks from bull sharks or crocodiles. Changes to river flows, such as by dams or droughts, can increase the risk faced by sawfish young by bringing them into more contact with predators. 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.

The combined range of the five sawfish species encompassed 90 countries, but today they have certainly disappeared entirely from 20 of these and possibly disappeared from several others. The sawfish is now presumed extinct in 55 nations (including China, Iraq, Haiti, Japan, Timor Leste, El Salvador, Taiwan, Djibouti and Brunei), with 18 countries with at least one species of sawfish missing and 28 countries with at least two. Violations can result in a fine of up to AU$121,900. 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). 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.

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. 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). and it is possible that the only remaining viable population is in the United States. However, the Florida population retains a high genetic diversity, This makes it "illegal to harm, harass, hook, or net sawfish in any way, except with a permit or in a permitted fishery". and all the remaining sawfish species were added in 2014, restricting trade in them and their parts in the United States. 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. Illegal fishing continues and in many countries enforcement of fishing laws is lacking. If protected their relatively low reproduction rates make these animals especially slow to recover from overfishing. 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 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. and this was repeated on the same date in 2018.