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Glaucostegus halavi 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rhinopristiformes Glaucostegidae

Scientific Name: Glaucostegus halavi (Forsskål, 1775)
Common Name(s):
English Halavi Guitarfish
Synonym(s):
Raja halavi Forsskål, 1775
Rhinobatos halavi (Forsskål, 1775)
Scobatus halavi (Forsskål, 1775)
Taxonomic Source(s): Last, P., White, W., de Carvalho, M., Séret, B., Stehmann, M. and Naylor, G. 2016. Rays of the World. CSIRO Publishing, Clayton.
Taxonomic Notes: This species was recently assigned to the subgenus Glaucostegus (Compagno 2005). Some recent changes in the systematics of Rhinobatus have elevated the subgenus Glaucostegus to full generic status and placed this genus into a family of its own: Glaucostegidae (Compagno 2005, Last et al. 2016).

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2d+3d ver 3.1
Year Published: 2017
Date Assessed: 2017-02-09
Assessor(s): Simpfendorfer, C., Jabado, R., Moore, A., Al Mamari, T. & Grandcourt, E.
Reviewer(s): Pollom, R. & Kyne, P.M.
Facilitator/Compiler(s): Jabado, R., Kyne, P.M.
Justification:
The Halavi Guitarfish (Glaucostegus halavi) occurs in shallow waters of the Red Sea, Gulf of Aden, Sea of Oman, the Arabian Gulf/Persian Gulf (hereafter referred to as the 'Gulf') and Arabian Sea to Pakistan and northern India (Gujarat). It is likely to grow slowly and mature late, giving it a low productivity. It is taken in variable quantities in gillnet and trawl fisheries, and habitat modification is a significant threat, particularly in the Gulf. There is preliminary evidence for declines of over 50% in the southern Gulf, and it would certainly have been impacted where heavy trawling pressure occurs off Gujarat (India) and probably elsewhere. Ongoing high levels of fishing pressure and coastal development are of concern, and overall it is suspected that the population would have declined by >30% over the last three generations (33 years). A further population reduction is suspected over the next three generation lengths (2017-2050) based on current levels of exploitation, and the species is assessed as Vulnerable A2d+3d.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Halavi Guitarfish is endemic to the Arabian Seas region, occurring in coastal waters of the Red Sea, Gulf of Aden, the Arabian Sea from Yemen to northern India (Gujarat) and the Gulf.
Countries occurrence:
Native:
Bahrain; Djibouti; Egypt; Eritrea; India (Gujarat); Iran, Islamic Republic of; Oman; Pakistan; Qatar; Saudi Arabia; Sudan; United Arab Emirates; Yemen
FAO Marine Fishing Areas:
Native:
Indian Ocean – western
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):Unknown
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:Unknown
Lower depth limit (metres):100
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Frequent misidentification in the past may have complicated inferences of relative population size of this species. A recent study has recorded landings in the UAE where it is the most commonly landed guitarfish (14.7% of rhinopristoids) (R.W. Jabado unpub. data). It is uncommonly landed in Bahrain (Moore and Peirce 2013) and in the Saudi Red Sea (Spaet and Berumen 2015). However, landings are common in the Sudanese Red Sea (I. Elhassan pers. comm. 07/02/2017) and it has been recorded from fishery landings in Oman (Henderson et al. 2007). In Pakistan, it is frequently caught, but is not abundant (M. Khan pers. comm. 07/02/2017).

Landings surveys in the UAE in recent years have demonstrated a rapid decline despite ongoing fishing effort; 10-20 individuals were regularly observed during 2010-2012, while landings of 1-2 individuals were more common five years later (R.W. Jabado unpub. data). In Pakistan, it has never been common and anecdotal information suggests that the population has only declined marginally (M. Khan pers. comm. 07/02/2017). Overall, this species is suspected to have declined by >30% across its range, with a further population reduction suspected over the next three generation lengths (2017-2050) based on current levels of exploitation.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:UnknownPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:UnknownAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

This species inhabits shallow sandy areas often less than 5 m, but occurs down to 100 m depth. The young are born at about 29 cm total length (TL) (Gohar and Mazhar 1964), and the maximum size reached is at least 187 cm TL (Moore and Peirce 2013). No data is available for age at maturity and size at maturity is believed to be around 83 cm TL (Last et al. 2016). Mature females produce litters of up to 10 young (Gohar and Mazhar 1964). The generation length is estimated from the Giant Guitarfish (Glaucostegus typus) from northern Australia (White et al. 2014) at ~11 years, but it is noted that the Halavi Guitarfish is substantially smaller than this species (which reaches 270 cm TL; Last et al. 2016).

Systems:Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):11
Movement patterns:Unknown

Use and Trade [top]

Use and Trade:

Guitarfish are considered to have high value fins fetching among the highest prices in Southeast Asia (Chen 1996). The meat of this species is often sold fresh for human consumption at local markets across the region and also enters the international trade in dried form. In countries such as Pakistan, it is highly valued for its fins and high quality flesh. Ray meat is increasing in demand and therefore prices in India are also increasing.

Threats [top]

Major Threat(s): The Halavi Guitarfish is taken in a variety of fisheries including demersal trawls, inshore set gillnets and set nets that are common throughout its range and through targeted fisheries in the northern Red Sea (Bonfil and Abdallah 2004). There is little information on catches of the Halavi Guitarfish as species-specific data is not always recorded, however the high level of exploitation on its habitat is of concern. For example, in the Saudi Red Sea, the number of traditional vessels operating increased from about 3,100 to 10,000 between 1988 and 2006 (Bruckner et al. 2011). In Iran, there is increasing fishing effort with the number of fishermen going from 70,729 in 1993 to 109,601 in 2002 (Valinassab et al. 2006). There were about 6,600 trawlers operating in the Indian state of Gujarat in the early 2000s (Zynudheen et al. 2004). This number increased to 11,582 trawlers in 2010 (CMFRI 2010). In Pakistan waters, about 2,000 trawlers operate in shelf waters, targeting shrimp in shallow waters and fish in outer shelf waters (M. Khan pers. comm. 06/02/2017). The species is also taken as bycatch off Oman and the UAE (R.W. Jabado pers. obs).

Its occurrence in very shallow water also makes it susceptible to coastal development and habitat degradation. Marine habitats in the Gulf are experiencing high levels of disturbance and quickly deteriorating due to major impacts from development activities (including dredging and reclamation), desalination plants, industrial activities, habitat destruction through the removal of shallow productive areas and major shipping lanes (Sheppard et al. 2010) which is likely to impact this species. Little is known of this species’ biology or habitat but, like other guitarfishes this species may be susceptible to population depletion due to similar life history characteristics that lead to low productivity.

Conservation Actions [top]

Conservation Actions: Kuwait and Pakistan are the only countries across the range of this species with regulations specifically banning catches of rays. Kuwait bans the catches of all rays, while Pakistan protects all guitarfishes, wedgefishes and the Bowmouth Guitarfish and therefore has specific regulations protecting this species. The UAE, Qatar and Oman have banned trawling in their waters (since 1980, 1993 and 2011, respectively) while Iran, Kuwait and Saudi Arabia have seasonal trawl bans that might benefit the species. However, incidental catches occur in other fisheries (e.g., gillnetting). Finning has also been banned in the UAE, Oman and Iran, yet trade statistics indicate that some trade in the fins and meat of this species still occurs.

Research is needed to determine distribution, population size and trends in abundance to further assess status and any future conservation needs.

Effective monitoring of fisheries is required, as is the effective implementation and management of marine protected areas. An education program on sustainable fishing and bycatch mitigation is needed for fishers.

Citation: Simpfendorfer, C., Jabado, R., Moore, A., Al Mamari, T. & Grandcourt, E. 2017. Glaucostegus halavi. The IUCN Red List of Threatened Species 2017: e.T161408A109902367. . Downloaded on 23 October 2017.
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