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Rhynchobatus springeri

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RHYNCHOBATIDAE

Scientific Name: Rhynchobatus springeri
Species Authority: Compagno & Last, 2010
Common Name(s):
English Broadnose Wedgefish
Synonym(s):
Rhynchobatus sp. nov. B in Last & Stevens, 1994
Taxonomic Notes: An undescribed but distinct species. Rhynchobatus sp. nov. B is part of the Indo-West Pacific Rhynchobatus djiddensis species complex (which includes R. djiddensis sensu stricto, R. australiae, Rhynchobatus sp. nov. B, and possibly R. cf. laevis). Separated from this complex is the Western Central Pacific Rhynchobatus sp. nov. A, and the eastern Atlantic R. luebberti (Compagno and Last 1999). Rhynchobatus sp. nov. B is sometimes confused with Rhynchobatus cf. laevis but only known to be sympatric with R. australiae and Rhynchobatus sp. nov. A. Rhynchobatus yentinensis Wang, 1933 (described from China) might be applicable to this species or may be a synonym of R. laevis.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2ad+3d+4ad ver 3.1
Year Published: 2006
Date Assessed: 2006-01-31
Assessor(s): Compagno, L.J.V. & Marshall, A.D.
Reviewer(s): Kyne, P.M., Heupel, M.R. & Simpfendorfer, C.A. (Shark Red List Authority)
Justification:
The undescribed broadnose wedgefish Rhynchobatus sp. nov. B has a restricted and fragmented distribution in coastal waters off Indonesia (Java), Singapore, peninsular Malaysia, the Philippines, and Thailand (Gulf of Thailand). A large species of guitarfish, verified to 213 cm total length (TL), but probably reaching 250 to 300 cm TL. Little known of its biology, although reproductive potential is inferred to be low based on size and fecundity of congeners. This species is irregularly caught as bycatch in local fisheries throughout its range but there are also reportedly directed fisheries for this species in Indonesia, the Philippines and Singapore. They are generally retained and utilized when taken as bycatch. Coastal rhynchobatid species, including Rhynchobatus sp. nov. B are highly susceptible to capture in a variety of fishing gear including inshore trawl nets, gill nets and line gear. Its flesh is highly sought after as are its fins, which are sold into the international fin trade. Fishing is intense and generally unregulated throughout the species' range and direct observations of bycatch numbers have indicated population declines of this naturally uncommon species (it was once moderately abundant but is now only irregularly taken). In particular, Indonesia has an extremely high level of exploitation on its marine resources, and this is only likely to increase into the future. Local extirpations of elasmobranch species (for example some eagle ray species; Compagno unpublished data) have occurred in the Gulf of Thailand and this raises immediate concern for Rhynchobatus sp. nov. B, a large coastal batoid with a significant proportion of its historical range in and around the Gulf of Thailand.

While exact data are unavailable, declines are known to have occurred throughout this species' range, indicated by observed bycatch levels. Actual exploitation levels of the marine environment are intense throughout its distribution, and there is the real potential for increased exploitation as the human population continues to rise in the region, and as demand for the international fin trade only increases. The restricted inshore habitat, probable limited biological characteristics, susceptibility to capture in various gear types, and ever growing demand place coastal rhynchobatids amongst the most vulnerable chondrichthyan fishes. The situation is heightened with respect to Rhynchobatus sp. nov. B which has a restricted and fragmented distribution. As such a Vulnerable assessment for Rhynchobatus sp. nov. B is warranted given direct observations of declines, and actual and potential levels of exploitation in the region. Continuing high levels of pressure in the region may result in a higher threat assessment in the future.

Geographic Range [top]

Range Description: Narrow geographic range with a fragmented distribution off northwestern Java (Indonesia), peninsular Malaysia, Thailand and the Philippines in the Western Central Pacific.
Countries:
Native:
Indonesia (Jawa); Malaysia; Philippines; Singapore; Thailand
FAO Marine Fishing Areas:
Native:
Pacific – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: A historically moderately abundant species. Observations of bycatch numbers have indicated population declines. Additional catch data and observations need to be made.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: An inshore species, benthic in coastal waters. One of the larger species of Rhynchobatus, probably reaching 250 to 300 cm TL (Compagno and Last 1999). Aplacental viviparous, but little is known of the species' biology. Given their size, rhynchobatids are suspected to have low fecundity and slow growth rates characteristic of large elasmobranchs. Rhynchobatus djiddensis from the Western Indian Ocean is reported to bear litters of four pups (van der Elst 1988).

Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total length): Female: unknown; Male: 125 cm TL (Compagno and Last 1999).
Longevity (years): Unknown.
Maximum size (total length): Verified to 213 cm TL, but probably up to 250 to 300 cm TL (Compagno and Last 1999).
Size at birth: <37 cm (L.J.V. Compagno unpublished data).
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: Unknown.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Systems: Marine

Threats [top]

Major Threat(s): The restricted inshore habitat, limited life history characteristics, susceptibility to capture in various gear types, and ever growing demand place coastal rhynchobatids amongst the most vulnerable chondrichthyan fishes. The situation is heightened with respect to Rhynchobatus sp. nov. B which has a fragmented distribution and a relatively small distribution.

This species is irregularly caught as bycatch in local fisheries throughout its range but there are also reportedly directed fisheries for this species in Indonesia, the Philippines and Singapore. They are generally retained and utilized when taken as bycatch. Coastal rhynchobatid species, including Rhynchobatus sp. nov. B are highly susceptible to capture in a variety of fishing gear including inshore trawl nets, gill nets and line gear. Its flesh is highly sought after as are its fins, which are sold into the international fin trade. Fishing is intense and generally unregulated throughout the species' range and direct observations of bycatch numbers have indicated population declines of this naturally uncommon species (it was once moderately abundant but is now only irregularly taken). In particular, Indonesia has an extremely high level of exploitation on its marine resources, and this is only likely to increase into the future. Local extirpations of elasmobranch species (for example some eagle ray species; L.J.V. Compagno unpublished data) have occurred in the Gulf of Thailand and this raises immediate concern for Rhynchobatus sp. nov. B, a large coastal batoid with a significant proportion of its historical range in and around the Gulf of Thailand.

Habitat modification/degradation, including to inshore nursery areas, from human activities (fisheries, pollution, coastal impacts) are likely affecting this species given its inshore range, particularly off Java and in the Gulf of Thailand, where human pressure on the coastal and marine environment is high.

Conservation Actions [top]

Conservation Actions: No direct conservation actions in place, although the banning of trawling around the island and territorial waters of Singapore is affording this species a limited amount of protection within this immediate area from this type of fishing. It is still, however heavily fished with other methods in that region.

There is a need to acquire accurate catch data from fisheries throughout the species' distribution and confirm presence in certain areas where it might have been previously been misidentified as other Rhynchobatus species. Needs better understanding of habitat requirements and critical area/habitats to establish best amelioration processes.

Harvest and trade management is needed, including control of fin trading activities. Livelihood alternatives may need to be sought for fishing communities.

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 management of all elasmobranch species in the region. See Anon. (2004) for progress made countries in the range of Rhynchobatus sp. nov. B towards National Plans of Action and towards a regional plan of action involving Indonesia, Malaysia, Thailand, the Philippines and other nations.

Citation: Compagno, L.J.V. & Marshall, A.D. 2006. Rhynchobatus springeri. The IUCN Red List of Threatened Species. Version 2014.1. <www.iucnredlist.org>. Downloaded on 23 July 2014.
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