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March Elasmobranch of the Month: Common (Longnose) Sawshark

Common (Longnose) Sawshark

(Pristiophorus cirratus)

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Key Features/Appearance

Common sawsharks get their name from their very long, flat, rostrum (snout) that may make up to 30% of its total body length. The rostrum has large teeth extending out on both sides, resembling a saw blade. The approximate 40 rostrum teeth alternate between a longer and a shorter one. A barbel extends from each side of the rostrum, roughly at the rostrum’s mid-point. The upper jaw of the common sawshark contains 39-49 rows of teeth. This shark is a relatively small species, growing to a maximum length of 1.37m (4.5 ft), weighing 8.5 kg (18.7 pounds). Its slightly flat, slender body is grayish-brown to pale yellow on the top side and whiteish colored underneath. Sometimes, dark patterns of spots, bars and blotches are visible on its back.

They have two dorsal fins with the first one only slightly larger than the second. These fins are located further down the body, with minimal space between the second dorsal and the start of the long, single-lobed caudal fin. Their pectoral fins are broad and rounded. This shark does not have anal fins.


Image credit Paddy Burke

Habitat and Distribution

The geographic range of the common sawshark is limited to the coast of southern Australia, in the Eastern Indian and Southwest Pacific Oceans. They may come closer to shore to bays and estuaries, but prefer sandy bottoms and water depths of 40- 300 m (131.2-984.3 ft).

Diet

The common sawshark’s diet includes bony fish, crustaceans, mollusks. They may use their saw-like rostrum to swipe at fish to injure them for easier capture.

Reproduction

Common sawshark reproduction takes place ovoviviparously. Embryos develop in eggs, inside the female, being nourished by yolk sacs. Once developed, the eggs hatch inside the female, then are birthed live. Gestation, is 12 months. Litter sizes range from 3-22 pups, each measuring approximately 31-34 cm (12.2 – 13.4 inches



Common Sawshark rostrum Credit Paddy Burke

Status

The IUCN Red List of Threatened Species currently lists the common sawshark as Least Concerned, with a stable population trend.


Threats

While not targeted by the commercial fishing industry, the industry has a large impact on the common sawshark population, as they are regularly killed as bycatch. When caught, the shark is traded for its meat. Common sawsharks are the natural prey of larger sharks.

References

Animal Diversity

https://animaldiversity.org/accounts/Pristiophorus_cirratus/

Krcmaric, D. 2006. "Pristiophorus cirratus" (On-line), Animal Diversity Web. Accessed March 13, 2022 at https://animaldiversity.org/accounts/Pristiophorus_cirratus/

Australian Fisheries Management Authority

https://www.afma.gov.au/fisheries-management/species/sawsharks

Fishes of Australia

https://fishesofaustralia.net.au/home/species/2018#moreinfo

Oceana

https://oceana.org/marine-life/longnose-sawshark/

Sharkwater

https://www.sharkwater.com/shark-database/sharks/long-nose-sawshark/

World of Sharks

https://www.world-of-sharks.com/longnose-sawshark.html

The IUCN Red List of Threatened Species

https://www.iucnredlist.org/species/39327/207778564

Walker, T.I. 2021. Pristiophorus cirratus (amended version of 2020 assessment). The IUCN Red List of Threatened Species 2021: e.T39327A207778564. https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T39327A207778564.en. Accessed on 13 March 2022.

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