The narrow sawfish (''Anoxypristis cuspidata''), also known as the pointed sawfish or knifetooth sawfish, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sawfish Sawfish, also known as carpenter sharks, are a family of very large 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 lar ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Pristidae Sawfish, also known as carpenter sharks, are a Family (biology), family of very large batoidea, rays characterized by a long, narrow, flattened rostrum (anatomy), rostrum, or nose extension, lined with sharp transverse plane, transverse teeth, ...

, part of the

Batoidea Batomorphi is a Division (taxonomy), division of Chondrichthyes, cartilaginous fishes, commonly known as rays, this taxon is also known as the Order (biology), superorder Batoidea, but the 5th edition of ''Fishes of the World'' classifies it as ...

, 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 (''Pristis'' and ''Anoxypristis''). The sawfishes are characterised by the long, narrow, flattened

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

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 The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the s ...

, ranging from the

Persian Gulf The Persian Gulf, sometimes called the Arabian Gulf, is a Mediterranean seas, mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula.Un ...

to southern

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

and northern

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. It is the only living member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Anoxypristis'', but was previously included in the

Pristis ''Pristis'' is a genus of sawfish of the family (biology), family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and Fresh water, freshwater lakes and rivers. Sawfish have ...

''. Compared to ''Pristis'', ''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). It reaches a length of up to . In addition to the living ''Anoxypristis cuspidata'', this genus includes a few extinct species that are only known from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

remains.

Description

The narrow sawfish grows to a maximum length of about , although there are highly questionable and unconfirmed claims of much larger individuals. Its body is generally shark-like, but its most obvious feature is the flattened head, which is extended forward in a blade-like bony snout with, in Australian waters, 18 to 22 pairs of sideways-facing teeth. However, elsewhere there may be as many as 25. These teeth are short, flat, and roughly triangular in shape. The blade does not taper towards its point and in adults, the basal one-quarter is devoid of teeth. In juveniles, about one-sixth of the base is toothless. The nostrils are narrow and partially concealed by nasal flaps. The skin of young sawfish is smooth, but on older individuals, it is sparsely covered in

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the us ...

s. The dorsal (upper) side of the fish is greyish and the ventral (lower) side and fins are a pale grey color. The rostrum is grey with white teeth and sometimes has a chocolate-brown base portion.

Distribution and habitat

The narrow sawfish was historically distributed across a broad swathe of the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

Ocean. It is, or was, present in the waters off Iran, India, Sri Lanka, Bangladesh, Malaysia, Burma, Indonesia, and Papua New Guinea. At its western extreme, it is present in the

Arabian Sea The Arabian Sea () is a region of sea in the northern Indian Ocean, bounded on the west by the Arabian Peninsula, Gulf of Aden and Guardafui Channel, on the northwest by Gulf of Oman and Iran, on the north by Pakistan, on the east by India, and ...

, extending as far south as

Somalia Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. The country is located in the Horn of Africa and is bordered by Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, th ...

. Its northern limit was the

Bohai Sea The Bohai Sea ( zh, c=渤海, p=Bó Hǎi, l=Bo Sea) is a gulf/inland sea approximately in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects via the Bohai Strait. It ...

, China, South Korea, and the most southerly parts of Japan, although its presence in the latter two countries may have been restricted to

vagrants Vagrancy is the condition of wandering homelessness without regular employment or income. Vagrants usually live in poverty and support themselves by travelling while engaging in begging, scavenging, or petty theft. In Western countries, ...

, and its southern limit is the northern Australian states of Western Australia, the Northern Territory, and Queensland. At present, it is known to exist only in the eastern Arabian Sea, parts of South Asia and Australia and Papua New Guinea. The narrow sawfish is bentho-pelagic and is found at depths of about . The narrow sawfish prefers soft bottom-substrates, such as sand, mud, or seagrass, to rocky or coraline habitats. It can tolerate low salinity levels and is found in inshore waters, including bays and estuaries. The narrow sawfish is

euryhaline Euryhaline organisms are able to adapt to a wide range of salinities. An example of a euryhaline fish is the short-finned molly, '' Poecilia sphenops'', which can live in fresh water, brackish water, or salt water. The green crab ('' Carcinus m ...

, meaning it can tolerate a wide range of salinity and move between estuarine and marine environments. It undergoes an

ontogenetic Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

shift in habitat. Larger individuals are commonly found offshore, whereas smaller individuals are found inshore. Females are also more likely to be found offshore. The narrow sawfish is suspected to be locally extinct in the coastal waters of Vietnam due to commercial fishing (especially trawling), coastal development, and subsequent habitat loss.

Behavior

Reproduction and life history

The breeding behavior of the narrow sawfish has been little studied. Fertilization is internal, and a number of young develop at one time in the

oviduct The oviduct in vertebrates is the passageway from an ovary. In human females, this is more usually known as the fallopian tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, or will dege ...

, each one being nourished from a

yolk sac The yolk sac is a membranous wikt:sac, sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac' ...

. Mating season varies by geographic region, and pups are born after a

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

al period of about five months. Litter sizes range from 6 to 23 pups with an average of 12. The pups are usually 43 – 61 cm long at birth, and their rostral teeth are not fully developed, being covered by a membrane, which prevents them from damaging the mother's tissues. Only two studies have been conducted on the age and growth of the narrow sawfish. The longest-lived narrow sawfish found was nine years old. However, the theoretical longevity is calculated to be 27 years. Females begin to mature at total length and are fully mature at . Males are fully mature at total length.

Temperament

The narrow sawfish is docile towards humans and not large enough to consider them as prey. If left undisturbed, it is harmless towards people. However, when highly stressed, such as when caught in a net, narrow sawfish will flail their heads from side to side to defend themselves. This can potentially inflict serious injury on unprotected persons who get too close.

Diet

The narrow sawfish feeds on small fish, squid, and invertebrates such as crabs and shrimp. It uses its rostrum in a side-to-side thrashing action to stir up the sediment and uncover concealed prey. It can also use its rostrum among schools of fish to incapacitate or stun individual fish. The head and rostrum of the sawfish contain thousands of electroreception organs called

ampullae of lorenzini Ampullae of Lorenzini (: ''ampulla'') are electroreceptors, sense organs able to detect electric fields. They form a network of mucus-filled pores in the skin of Chondrichthyes, cartilaginous fish (sharks, Ray (fish), rays, and chimaeras) and of ...

, which allow it to sense and locate the electric fields of its prey. The narrow sawfish is itself

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

to various sharks such as the

hammerhead shark The hammerhead sharks are a group of sharks that form the family Sphyrnidae, named for the unusual and distinctive form of their heads, which are flattened and laterally extended into a Hammerhead shark#Cephalofoil, cephalofoil (a T-shape or " ...

(''Sphyrna'' spp.), the

bull shark The bull shark (''Carcharhinus leucas''), also known as the Zambezi shark (informally zambi) in Africa and Lake Nicaragua shark in Nicaragua, is a species of requiem shark commonly found worldwide in warm, shallow waters along coasts and in riv ...

(''Carcharhinus leucas'') and the

copper shark The copper shark (''Carcharhinus brachyurus''), bronze whaler, or narrowtooth shark is a species of requiem shark found mostly in temperate latitudes. It is distributed in a number of separate populations in the northeastern and southwestern Atla ...

(''Carcharhinus brachyurus'') and also the

saltwater crocodile The saltwater crocodile (''Crocodylus porosus'') is a crocodilian native to saltwater habitats, brackish wetlands and freshwater rivers from India's east coast across Southeast Asia and the Sundaland to northern Australia and Micronesia. It ha ...

(''Crocodylus porosus'').

Conservation status

Threats

Human actions are the main cause of the declining narrow sawfish populations and ranges. Overutilization, primarily from commercial fisheries, is its biggest threat. Narrow sawfish populations have likely decreased over 80% between 2004 and 2022. The narrow sawfish is a high-value target for fishermen. Sawfish are commonly hunted to make shark fin soup or for their rostrums to be displayed as trophies. Most countries have regulations against catching it; however, illegal, unreported, and unregulated fishing remains a threat. Furthermore, the narrow sawfish is or was a common bycatch for fisheries in its geographic range. The toothed rostrum makes it vulnerable to most types of fishing gear, particularly nets, with those made of nylon more difficult for sawfish to extricate themselves from. Damaged, neglected, or lost fishing gear (aka ghost nets) are also a considerable threat to narrow sawfish. Pregnant females and juveniles are at the highest risk for this threat. Additionally, the narrow sawfish has high post-release mortality, exacerbated by the difficulty of removing sawfish from fishing equipment. Habitat loss and water pollution are also threats to the narrow sawfish. Coastal development, coastline urbanisation, and an expanding mining industry result in the modification and destruction of critical habitat. Furthermore, the pollution from these activities degrades the water quality. As of 2020, narrow sawfish may no longer be present in up to 61% of their historic range, according to the IUCN. These threats are expected to become more significant as the human population grows. Natural threats, such as disease and predation, do not significantly harm the narrow sawfish population.

IUCN status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

listed the narrow sawfish as "

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

" in its

Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

in the year 2000. This was due to the threats of overutilization, habitat loss, and a decreasing population. Its status was updated to "Critically Endangered" in 2006. In 2013, its status returned to "Endangered" due to the availability of new information. The 2023 assessment again categorized it as critically endangered, citing an estimated decrease in the global population by more than 80% in three sawfish generations or 18 years.

ESA listing

On September 10, 2010, WildEarth Guardians petitioned the US

National Marine Fisheries Service The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the ste ...

(NMFS) to list six sawfish species – the narrow sawfish; the dwarf sawfish, the freshwater sawfish, the common sawfish, the narrowsnout sawfish, and the

smalltooth sawfish The smalltooth sawfish (''Pristis pectinata'') is a species of sawfish in the family (biology), family Pristidae. It is found in shallow tropical and subtropical waters in coastal and estuarine parts of the Atlantic. Reports from elsewhere are no ...

– as endangered or threatened under the

Endangered Species Act of 1973 The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...

. The NMFS published a 90-day review on March 7, 2011, stating that action may be warranted for five of the six species. Information available at the time indicated that the common sawfish was not a valid species. On June 4, 2013, the NMFS published a proposal that concluded all five sawfish species were at high risk for

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. The proposal listed habitat loss, water quality, and overutilization as the biggest threats to the narrow sawfish. The NMFS published its final ruling on December 12, 2014, which listed all five sawfish species as endangered. Scientific data showed that geographical areas occupied by the narrow sawfish were entirely outside U.S. jurisdiction. Therefore, the NMFS was not able to designate any critical habitat. Furthermore, the NMFS did not develop a recovery plan because they would not be able to enforce it.

Conservation efforts

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

and

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

have listed protections for the Narrow Sawfish as a "no-take" species. Sawfish also are considered "no-take" species in India, but the legislation is frequently ignored and rarely enforced. International trade of the narrow sawfish has been banned by its inclusion in the

Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

(CITES) Appendix 1. The current population of the narrow sawfish is unknown.

References

External links

Species Description of Anoxypristis cuspidata at www.shark-references.com

Fishes of Australia : Narrow Sawfish, ''Anoxypristis cuspidata''
{{Taxonbar, from=Q135965 knifetooth sawfish Fish of South Asia Marine fish of Southeast Asia Ovoviviparous fish Endangered fish Endangered biota of Africa knifetooth sawfish knifetooth sawfish ESA endangered species Endangered Fauna of China