The dwarf sawfish or Queensland sawfish, ''Pristis clavata'', is a

sawfish 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 ...

of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Pristidae 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 ...

, found in tropical Australia. This endangered species is the smallest species in its family.

Description

Pristis clavata (Dwarf sawfish) in Aqua park shinagawa

The dwarf sawfish has a torpedo-shaped body that resembles that of a shark, and grows to a length of about . It has broad, triangular pectoral fins and large, upright dorsal fins. The first dorsal fin is located directly above, or slightly behind, the origins of the pelvic fins, and the caudal fin has a very small lower lobe. The snout is broad and flat and is elongated into a

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * 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 ships * Ros ...

with around twenty pairs of rostral teeth. This fish is usually greenish-brown, or occasionally yellowish-brown, on its dorsal surface, and whitish underneath.

Distribution and habitat

The dwarf sawfish is native to the western and central Indo-Pacific region and historically had a much wider range than it does now. Its present confirmed range is from the

Cape York Peninsula Cape York Peninsula is a large peninsula located in Far North Queensland, Australia. It is the largest unspoiled wilderness in northern Australia.Mittermeier, R.E. et al. (2002). Wilderness: Earth’s last wild places. Mexico City: Agrupació ...

, Queensland, to the northern

Pilbara The Pilbara () is a large, dry, thinly populated region in the north of Western Australia. It is known for its Aboriginal peoples; its ancient landscapes; the red earth; and its vast mineral deposits, in particular iron ore. It is also a g ...

region of Western Australia. A recorded sighting from the Canary Islands was probably of a different species. It typically inhabits inshore waters, estuaries, tidal mudflats and sometimes the lowest reaches of rivers.

Ecology

This sawfish feeds mainly on fish, but also eats molluscs and crustaceans. The rostrum has large numbers of pores adapted for

electroreception Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to st ...

and is probably also used to manipulate prey. Its sensory input helps the fish move about in the muddy waters in which it often lives. Although they are sometimes found in deep water, most movements take place while the tide is either rising or falling, and movements during each tidal cycle may be up to . At high tide the fish tend to forage and rest among the

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

s. Little is known of the breeding habits of the dwarf sawfish. The fish are

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

with the developing embryos feeding on the yolks of their eggs. It is not known how many young can be carried at one time nor how frequently the fish can breed, but the young are about long when they are born. Maximum longevity in this species is estimated to be forty-eight years.

Status

The dwarf sawfish is protected in Australian waters, but elsewhere in the world, sawfishes are harvested for their meat, fins, rostrums and oil. The main threat facing the dwarf sawfish is being caught as bycatch in gillnets and trawl nets. That this is the cause of declining numbers is demonstrated by the fact that populations are declining fastest in heavily fished areas. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

has assessed the conservation status of this fish 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 and in ...

". There is a need for education of fishermen about safe release practices and how to manage their fisheries. However, the threats are continuing, and there is no reason to believe that the population of dwarf sawfish is recovering from previous declines. Due to the decrease in the number of individuals, this species is rarely stored in aquariums, and as of 2021, 2 individuals (1 males 1 females) are captivity only in the Japanese public aquariums Aqua Park Shinagawa.

References

5. (Sensory Systems in Sawfishes. 1. The Ampullae of Lorenzini) https://www.researchgate.net/profile/Barbara_Wueringer/publication/51559323_Sensory_systems_in_sawfishes._1._The_ampullae_of_Lorenzini/links/09e415091dacec5f51000000.pdf

External links

* *
Species Description of Pristis clavata at www.shark-references.com
{{Taxonbar, from=Q244406

Pristis ''Pristis'' is a genus of sawfish of the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maint ...