Knifetooth sawfish
Narrow sawfish | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Superorder: | Batoidea |
Order: | Rhinopristiformes |
Family: | Pristidae |
Genus: | Anoxypristis Moy-Thomas , 1941
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Species: | A. cuspidata
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Binomial name | |
Anoxypristis cuspidata (Latham, 1794)
| |
Synonyms | |
Pristis cuspidatus |
The narrow sawfish (Anoxypristis cuspidata), also known as the pointed sawfish or knifetooth sawfish, is a
In addition to the living Anoxypristis cuspidata, this genus includes a few extinct species that are only known from fossil remains.[6][7]
Description
The narrow sawfish grows to a maximum length of about 3.5 m (11 ft), although there are highly questionable and unconfirmed claims of much larger individuals.
Distribution and habitat
The narrow sawfish is distributed across a broad swathe of the
The narrow sawfish is euryhaline, meaning it can tolerate a wide range of salinity and move between estuarine and marine environments. It undergoes an ontogenetic shift in habitat. Larger individuals are commonly found offshore, whereas smaller individuals are found inshore. Females are also more likely to be found offshore.[4]
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.[10]
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, each one being nourished from a yolk sac.[5] Mating season varies by geographic region, and pups are born after a gestational period of about five months.[5][4] 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.[5]
Only two studies have been conducted on the age and growth of the narrow sawfish. The longest lived narrow sawfish found was 9 years old. However, the theoretical longevity is calculated to be 27 years. Females begin to mature at 8 feet 1 inch total length and are fully mature at 15 feet 5 inches. Males are fully mature at 8 feet total length.[4]
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.[5]
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, which allow it to sense and locate the electric fields of its prey. The narrow sawfish is itself prey to various sharks such as the hammerhead shark (Sphyrna spp.), the bull shark (Carcharhinus leucas) and the copper shark (Carcharhinus brachyurus) and also the saltwater crocodile (Crocodylus porosus).[5]
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.[4] Narrow sawfish populations have likely decreased between 50 and 70% over the last 20 years. 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 a common bycatch for fisheries in its geographic range. The toothed rostrum makes it vulnerable to most types of fishing gear, particularly nets. 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 the highest post-release mortality of any sawfish species.[11]
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. The narrow sawfish range is suspected to have declined by 30% from historic extent. 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.[4]
IUCN status
The
ESA listing
On September 10, 2010, WildEarth Guardians petitioned the US
Conservation efforts
Western Australia and Queensland 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) Appendix 1.[10]
Current population of the narrow sawfish is unknown.[10]
See also
- Threatened rays
Collareta, Alberto; Casati, Simone; Catanzariti, Rita; Di Cencio, Andrea (2017). "First record of the knifetooth sawfish Anoxypristis (Elasmobranchii: Rhinopristiformes) from the Pliocene of Tuscany (central Italy)". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 284 (3): 289–297. .
References
- ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Chondrichthyes entry)". Bulletins of American Paleontology. 364: 560. Archived from the original on 2011-09-30. Retrieved 2008-01-09.
- . Retrieved 19 November 2021.
- ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
- ^ a b c d e f g "Endangered and Threatened Wildlife and Plants; Final Endangered Listing of Five Species of Sawfish Under the Endangered Species Act". Federal Register. 2014-12-12. Retrieved 2020-04-19.
- ^ a b c d e f g h i "Anoxypristis cuspidata". Florida Museum. 2017-05-10. Retrieved 2020-04-19.
- S2CID 3352391.
- ^ "Fossilsawfish.com". Fossilsawfish.com. Retrieved 2020-04-19.
- ^ "Anoxypristis cuspidata summary page". FishBase. Retrieved 2020-04-19.
- ^ a b "Endangered and Threatened Wildlife and Plants; 12-Month Finding and Proposed Endangered Listing of Five Species of Sawfish Under the Endangered Species Act". Federal Register. 2013-06-04. Retrieved 2020-04-19.
- ^ a b c "Narrow Sawfish | Anoxypristis Cuspidata | Shark Database". www.sharkwater.com. Retrieved 2020-04-19.
- ^ . Retrieved 2020-04-19.
- ^ WildEarth Guardians (2010). “A Petition: Requesting the Secretary of Commerce to Add Six Critically Endangered Sawfish Species to the List of Threatened and Endangered Species Maintained Under the Authority of the Endangered Species Act.” NOAA Fisheries. Retrieved 27 May 2020
- ^ "Listing Endangered and Threatened Species: 90-Day Finding on a Petition to List Six Species of Sawfishes as Endangered or Threatened Species Under the Endangered Species Act". Federal Register. 2011-03-07. Retrieved 2020-04-19.