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Pliotrema warreni

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES PRISTIOPHORIFORMES PRISTIOPHORIDAE

Scientific Name: Pliotrema warreni
Species Authority: Regan, 1906
Common Name(s):
English Sixgill Sawshark
French Requin Scie Flutian

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2004
Date Assessed: 2004-04-30
Assessor(s): Fowler, S.L.
Reviewer(s): Human, B., Cavanagh, R.D. & Kyne, P.M. (Shark Red List Authority)
Justification:
Pliotrema warreni is a southern African endemic with a relatively restricted geographic distribution, depth range of 37 m to at least 500 m, and possibly a discontinuous habitat distribution. Likely a relatively unproductive species, with fairly small litters and relatively large size at maturity compared with some other sawsharks. Vulnerable to net gear because of its morphology. Taken as discarded, unmonitored bycatch in demersal trawlers throughout much of its range. Although population and trend data are lacking, levels of bycatch of this species are considered likely to be unsustainable. P. warreni is assessed as Near Threatened due to concerns regarding its vulnerability to this unmonitored fishing pressure and its restricted distribution.

Geographic Range [top]

Range Description: Warm-temperate and subtropical continental shelves and upper slopes from the Western Cape of South Africa to southern Mozambique and southeastern Madagascar. Normally absent from the cold-temperate west coast of South Africa, north from Cape Town. Depth range 37 m to at least 500 m. Bimodal distribution off the southern Cape Coast of South Africa. Most records are from between 20 and 21° on the outer continental shelf of the Western Cape (Cape Agulhas and Cape Infanta, 60 to 160 m, mostly 70 to 140 m) and between 25 and 27° longitude on continental shelf and upper slope of Eastern Cape from Port Elizabeth to Port Alfred (70 to 290 m, mostly 80 to 120 m). Few intermediate records between these two areas, no records below 300 m on the Cape coast. Possible pupping grounds in Eastern Cape (near Algoa Bay) and off KwaZulu-Natal.

Off central KwaZulu-Natal, occurs at 73 to 430 m, mostly below 110 m. Has been taken at 360 m off Delagoa Bay, Mozambique and at 425 to 500 m off southeastern Madagascar (Compagno in prep. a).
Countries:
Native:
Moldova; Mozambique; South Africa
FAO Marine Fishing Areas:
Native:
Atlantic – southeast; Indian Ocean – western
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Apparently common or formerly common off the southern Cape coast of South Africa.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Offshore benthic and epibenthic species on the warm-temperate and subtropical continental shelves and upper slopes of southern Africa and Madagascar at 37 m to at least 500 m, with apparent tropical submersion northeastwards along its range and onto the uppermost slopes. Bimodal distribution in South African Cape waters may be linked to restricted habitat (possibly related to feeding).

Biology, ecology and behaviour sketchily known. Ovoviviparous, with 5 to 7 pups/litter (but 7 to 17 developing eggs recorded). Populations partially segregated; young occur in shallower water than adults off KwaZulu-Natal, South Africa. Possible pupping grounds in Eastern Cape (near Algoa Bay) and off KwaZulu-Natal. Feeds on small fish, crustaceans and squid. Predators poorly known but include tiger shark (Compagno in prep. a).

Known life history parameters
Size at maturity: 110 cm total length (TL) (females); 83 cm TL (males).
Maximum size: at least 112 cm TL (males) and 136 cm TL (females).
Size at birth: 35 to 37 cm TL.
Average annual fecundity or litter size: 5 to 7 young per litter in two females; others with 1 to 17 eggs.
Systems: Marine

Threats [top]

Major Threat(s): Bycatch of demersal bottom trawlers off South Africa and southern Mozambique. Intensive offshore trawl fisheries occur in its known range, but trends in occurrence of this species as bycatch are unmonitored. It is apparently unutilized and discarded (Compagno in prep. a). Probably not sufficiently common in bycatch to be worth marketing.

Citation: Fowler, S.L. 2004. Pliotrema warreni. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 18 September 2014.
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