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Negaprion acutidens

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES CARCHARHINIFORMES CARCHARHINIDAE

Scientific Name: Negaprion acutidens
Species Authority: (Rüppell, 1837)
Infra-specific Taxa Assessed:
Common Name(s):
English Sharptooth Lemon Shark

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2abcd+3bcd+4abcd ver 3.1
Year Published: 2003
Date Assessed: 2003-04-30
Annotations:
Needs updating
Assessor(s): Pillans, R. (SSG Australia & Oceania Regional Workshop, March 2003)
Reviewer(s): Cavanagh, R.D., Kyne, P.M., McAuley, R. & White, W.T. (Shark Red List Authority)
Justification:
A widely distributed tropical Indo-west and central Pacific inshore species usually associated with coral reefs, lagoons and mangrove estuaries, and which exhibits very limited movement patterns. Within Australian waters, this species is wide-ranging and captured in small numbers in gillnets, beachmeshing and longlines on the east coast and Northern Territory. Catches in Western Australia are also small. In Australia, there are likely to be significant areas of unfished habitat outside the operational ranges of these fisheries, thus the population is assessed as Least Concern. Outside Australia, this species is heavily fished in unregulated and expanding inshore fisheries throughout its range, and this, together with its narrow habitat range and limited potential for recolonisation of heavily fished sites, leads to a global assessment of Vulnerable. Further, in Indonesia there has been little recent evidence of this species at fish markets although it was historically abundant. Widespread damage and destruction of coral reefs and mangrove habitats in parts of South East Asia are also cause for concern. In addition there are records of local extinctions in India and Thailand. This species is assessed as Endangered in South East Asia.

Geographic Range [top]

Range Description: Wide ranging in the Indian Ocean and western Central Pacific, extending from South Africa to the Australian region and Oceania (Compagno and Niem 1998). Within Australia, from Moreton Bay (Queensland) to the Abrolhos Islands (Western Australia) (Last and Stevens 1994).
Countries:
Native:
Australia (Northern Territory, Queensland, Western Australia); Fiji; India; Indonesia; Madagascar; Myanmar; Papua New Guinea; Solomon Islands; South Africa; Thailand; Vanuatu
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern; Indian Ocean – western; Pacific – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Gestation period: 10 to 11 months
Reproductive periodicity: two years
Size at birth: 60 cm total length (TL)
Average litter size: 9.3 (6 to 12)
Size male maturity: 220 cm TL
Size female maturity: 220 cm TL
Max size: 300 cm TL
Growth rates, Juveniles: 12.5 to 15.5 cm/yr

Occurs in tropical, shallow inshore and offshore waters near the bottom; often found on and around coral reefs and on sandy plateaus near coral, at depths down to at least 30 m (Compagno and Niem 1998). Often found inside coral lagoons but also on reef flats and reef edges (Stevens 1984). It is also known to occur around and within mangrove estuaries (W. White pers.comm.).

Out of 143 animals tagged at 43 sites by Stevens (1984), 19 individuals were recaptured (14.5%) of which five were caught more than once. These data showed that 52% of recoveries were made at the tagging site, 83% within 1 km of tagging site and 91% within 2 km. The average distance moved by individuals was 1.3 km (excluding those animals that did not move from tagging site) and the maximum distance traveled was 5 km.
Systems: Marine

Threats [top]

Major Threat(s): Within Australia, data from the Northern Territory (Lyle et.al. 1984) indicated that catch rates of N. acutidens in gill net and long line fishing trials were very low. N. acutidens is taken in small quantities (approximately 15 tonnes/yr) in the Western Australia northern shark fisheries. These fisheries comprise a very small number of boats (13 licenses, seven active and only three fishing for six months or more) operating over a very large length of coast. A smaller quantity of N. acutidens are also taken as bycatch in trawl and gillnet fisheries in northern Western Australia waters. There are likely to be significant areas of unfished habitat outside the operational ranges of these fisheries (R. McAuley, pers.comm).

Threats from inshore fisheries are high outside Australian waters, particularly Southeast Asia, where these sharks are captured by gillnets and longlines. They are particularly susceptible to local depletion due their very small habitat range and limited movement patterns (Stevens 1984). This species is also likely to be affected by habitat destruction, particularly in South East Asia. For example, extensive coral reef habitat destruction (pollution and dynamite fishing), in addition, this species is known to occur around and within mangrove estuaries, many of which have been deforested or are heavily populated by humans throughout its range (William White, pers.comm.).

Although they are still recorded, albeit very infrequently within Indonesia (W. White, pers. comm.), evidence suggests N. acutidens was historically more abundant, and have not been seen for several years in some areas. For example, in a preliminary survey of market catches around Bali, no N. acutidens were recorded, and jaws held in the fisheries centre in Jakarta that were several years old were the only evidence that this species was once caught in the region (W. White, pers. comm.). Furthermore, evidence of local extinctions in India and Thailand (L.J.V. Compagno, pers. comm.) indicates that this species is extremely susceptible to local inshore fisheries.

Conservation Actions [top]

Conservation Actions: There are currently no conservation measures in place for this species.

Bibliography [top]

Compagno, L.J.V. 1998. Carcharhinidae. In: K.E. Carpenter and V.H. Niem (eds). FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 2. Cephalopods, crustaceans, holothurians and sharks. FAO, Rome, pp. 1312-1360.

IUCN. 2003. 2003 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 18 November 2003.

IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.

Last, P.R. and Stevens, J.D. 1994. Sharks and Rays of Australia. CSIRO, Australia.

Lyle, J.M., Pyne, R.R., Hooper, J. and Croaker, S.L. 1984. North Australia's multi-species shark fishery - a preparatory evaluation of the development of a shark fishing industry in northern territory waters. North Australia's Multi-Species Shark Fishery 1(12): 1-36.

Stevens, J.D. 1984. Life history and ecology of sharks at Aldabra Atoll, Indian Ocean. Royal Society of London. Proceedings. Biological Sciences. 222(1226): 79–106.


Citation: Pillans, R. (SSG Australia & Oceania Regional Workshop, March 2003) 2003. Negaprion acutidens. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 November 2014.
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