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Gymnura poecilura

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES GYMNURIDAE

Scientific Name: Gymnura poecilura
Species Authority: (Shaw, 1804)
Common Name(s):
English Longtail Butterfly Ray
Taxonomic Notes: The relationship between the subpopulation occurring in French Polynesia and the rest of the species' range may require critical examination.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2006
Date Assessed: 2006-01-31
Assessor(s): Bizzarro, J.J. & White, W.T.
Reviewer(s): Kyne, P.M., Compagno, L.J.V., Fowler, S.L. & Cavanagh, R.D. (Shark Red List Authority)
Justification:
Gymnura poecilura has a widespread but apparently disjunct distribution in the Indo-West Pacific. The species has long been targeted in India, Thailand, Indonesia and likely elsewhere by artisanal and commercial fisheries for human consumption. Very little is known about most aspects of its biology and no recent quantitative information is available to determine population structure or fluctuations and potential fishery impacts. It is restricted to the inner continental and coastal shelves with a narrow depth range (to ~30 m), which is heavily exploited throughout much of its range. Furthermore, exploitation in these regions is only likely to increase into the future. Fecundity appears to be low, being reported up to seven pups/litter, and females are known to commonly abort embryos upon capture. With a lack of data to quantify declines which may confirm this species is in fact threatened, at least in some regions, Gymnura poecilura is assessed as Near Threatened globally due to the high level of exploitation through much of its range, its restricted habitat and declines in closely related sympatric species, such as the zonetail butterfly ray Aetoplatea zonura. The longtail butterfly ray is highly susceptible to a variety of gear types and its restricted life history limits its ability to recover from population depletion. Monitoring of catches of this species throughout its range is required without delay.

Geographic Range [top]

Range Description: Found in shallow, inshore waters of the Red Sea, Somalia and Oman and from Pakistan through the eastern Indian Ocean and north from Indonesia to southern Japan in the western Pacific, as well as an isolated population in French Polynesia (Compagno and Last 1999). May occur between Oman and Pakistan as well, but not reported.
Countries:
Native:
China; Egypt; Eritrea; French Polynesia; India; Indonesia (Jawa, Kalimantan, Sumatera); Japan; Malaysia; Oman; Pakistan; Philippines; Saudi Arabia; Somalia; Sri Lanka; Sudan; Thailand; Viet Nam; Yemen
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern; Indian Ocean – western; Pacific – eastern central; Pacific – northwest; Pacific – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: No other information on the abundance, population size, or degree of fragmentation of this species is known from its range.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Extremely limited biological or life history information is available for this species. It is known to occur in shallow, inshore waters throughout its range (to ~30 m depth), typically on sand or mud substrate (James 1966, Compagno and Last 1999).

James (1966) published all the available reproductive information on G. poecilura from fishery-derived specimens taken in India. This species is aplacental viviparous, with two functional ovaries. Maximum fecundity was determined to be seven and there is no apparent relationship between fecundity and size of gravid females. Spontaneous abortion is, however, common in this species upon capture, which may confound these determinations. It is thought to breed nearly year-round, with a peak in parturition between April and October (James 1966).

Maximum size reported as either 91.5 cm DW or 98.5 cm DW. This confusion is a result of conflicting information listed in James (1966). Since a later publication (James 1973) referred to the former value, it is considered to be the valid maximum size. No age and growth studies have been conducted. Based on limited observations in India, the diet includes fishes (especially Leiognathus spp.), molluscs and crustaceans (James 1966). No other published literature is available for this species throughout its range.

Life history parameters
Age at maturity (years): Unknown.
Size at maturity (disc width): 41.0 cm DW (assumed first maturity), 66.0 cm DW (smallest gravid female recorded) (James 1966) (female); Unknown (male).
Longevity (years): Unknown.
Maximum size (disc width): 91.5 cm DW (verified: James 1966, 1973), 98.5 cm DW (questionable; James 1966).
Size at birth: 23.7 to 25.6 cm DW (James 1966).
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Year-round or nearly year-round (James 1966).
Average annual fecundity or litter size: Fecundity reported to seven, but females may pup more than once per year and fecundity is likely underestimated as a result of spontaneous abortion (James 1966)..
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Systems: Marine

Threats [top]

Major Threat(s): Considerable parts of this species' range are subject to intensive inshore fisheries (for example Indonesia and Thailand both with high pressure on their marine resources, which is only likely to increase in the future). Directed artisanal and commercial trawl and bottomset gillnet fisheries have been historically reported in Palk Bay and the Gulf of Mannar, India, but no recent published literature is available to document current fishing trends (James 1966). Based on historic information, G. poecilura occurred in landings year-round, with a peak of abundance between January and May. The dominant size range in this fishery ranged from 35 to 70 cm DW (James 1966). It is also currently targeted in Thailand and Indonesia for human consumption by artisanal fisheries and is also caught as bycatch in other artisanal and commercial fisheries throughout its range (Compagno and Last 1999, W. White unpubl. data).

Although no specific information is available, habitat loss and degradation may also be affecting this species given its inshore coastal occurrence.

Conservation Actions [top]

Conservation Actions: There are no conservation measures in place for this species throughout its range. Direct and indirect catches in artisanal and commercial fisheries throughout its distribution need to be documented.

The development and implementation of management plans (national and/or regional e.g. under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and sustainable management of all chondrichthyan species in the region. See Anon. (2004) for an update of progress made by nations in the range of G. poecilura.

Citation: Bizzarro, J.J. & White, W.T. 2006. Gymnura poecilura. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 18 September 2014.
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