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Glaucostegus halavi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RHINOBATIDAE

Scientific Name: Glaucostegus halavi
Species Authority: (Forsskål, 1775)
Common Name(s):
English Halavi Guitarfish
Synonym(s):
Raja halavi Forsskål, 1775
Rhinobatos halavi (Forsskål, 1775)
Taxonomic Notes: This species was recently assigned to the subgenus Glaucostegus (Compagno 2005). Some recent changes in the systematics of this group have elevated the subgenus Glaucostegus to full generic status (Compagno 2005).

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2009
Date Assessed: 2008-12-01
Assessor(s): Barnett, L.A.K., Ebert, D.A. & Henderson, A.
Reviewer(s): Valenti, S.V. & Fowler, S.L. (Shark Red List Authority)
Justification:
The Halavi Guitarfish (Rhinobatos halavi) is a poorly known guitarfish confirmed from the Red Sea and Gulf of Oman, but likely occurring off the adjacent coastlines of the Gulf of Aden and northwestern Arabian Sea. Reports from the Mediterranean Sea and the coasts of India, Myanmar, Philippines, Vietnam, China, Australia, and West Africa are all unconfirmed. Frequent misidentification complicates any inference of relative population size. A target and utilized bycatch in fisheries, but appears to have some refuge from fishing pressure in certain areas (e.g., Oman). Lack of information about abundance, combined with limited knowledge of the extent of fishing pressure impacting this species necessitates a Data Deficient classification at present. Research is required better to define its distribution and to determine population trends.

Geographic Range [top]

Range Description: Western Indian Ocean: confirmed reports from the Red Sea and the Gulf of Oman only, but likely occurring off the adjacent coastlines of the Gulf of Aden and Northwestern Arabian Sea (Randall and Compagno 1995). Unconfirmed reports from the Mediterranean Sea (Ben-Tuvia 1966, Ben Souissi et al. 2007), and the coasts of India, Myanmar, Philippines, Vietnam, China, Australia, and West Africa (Fowler 1941).
Countries:
Native:
Djibouti; Egypt; Eritrea; Japan (Honshu); Oman; Saudi Arabia; Yemen
FAO Marine Fishing Areas:
Native:
Indian Ocean – western
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Common in the northwestern Red Sea during the pupping season, from May to October (Gohar and Mazhar 1964). Frequent misidentification complicates any inference of relative population size. Elasmobranch research has been very limited so far within the northern Indian Ocean (Henderson et al. 2007).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Off Oman, juveniles and adults are apparently found in shallow (<5 m) inshore waters, mainly sheltered bays (A. Henderson pers. obs. 2007). The young of this species appear to stay in very shallow water, sometimes allowing the breakers to wash them up onto the beach (almost completely out of the water), before sliding back down into the water (A. Henderson pers. obs. 2007).

The species is exhibits aplacental viviparity (Compagno 1990). Maximum size is 171 cm total length (TL) (Gohar and Mazhar 1964). Females aggregate in the northwestern Red Sea from May to October give birth in shallow, sandy habitat (Gohar and Mazhar 1964). Females give birth to <10 pups per litter. Size at birth is about 29 cm TL (Gohar and Mazhar 1964) (Gohar and Mazhar 1964).
Systems: Marine

Threats [top]

Major Threat(s): A target and utilized bycatch in fisheries, but the amount of catch relative to stock size is not known (Bonfil and Abdallah 2004). Aggregation behavior during spawning may make this species particularly vulnerable to exploitation.

Off Saudi Arabia, in the Red Sea, artisanal fisheries production is almost entirely from handline and gillnet methods, while the industrial fleet utilizes fish and shrimp trawl nets and purse seine nets (FAO 2007). The industrial vessels operating in the Red Sea utilize trawl nets to target both demersal fish stocks and shrimp, with the majority of these vessels belong to Saudi Fisheries Company and operate out of Jizan on the southern Red Sea coast (FAO 2007).

Oman has a long established traditional shark fishery, which has experienced increased demand in recent years due to the shark fin trade (Henderson et al. 2007). In Omani waters, elasmobranchs are mainly captured by artisanal fishermen using wooden dhows and fiberglass skiffs with bottom-set longlines, bottom-set gillnets and driftnets (Henderson et al. 2007). The majority of fishing takes place in water shallower than 100 m and is therefore confined to inshore areas (Henderson et al. 2007). The presence of this species in shallow inshore areas would seem to put them at risk of capture in fisheries, but fishermen in Oman prefer to focus their fishing efforts in deeper waters where they catch grouper and other more valuable species (A. Henderson pers. obs. 2007). The fishermen operating in shallow coastal waters tend to surface-gillnet around reefs, or cast net for sardines and similar species, so the this species doesn't appear to be under much pressure in Oman (A. Henderson pers. obs. 2007). It is taken as incidental bycatch in Oman, and these catches appear to be limited to the Gulf of Oman (from Musandam in the north, to Muscat) (A. Henderson pers. obs. 2007). Landings of this species reported in (Henderson et al. 2007) all came from a single haul, thus artificially elevating the species' importance in the landings for that region.

Conservation Actions [top]

Conservation Actions: There are several marine protected areas throughout the species' range (Wood 2007). However, there are no species-specific management measures. Research is ongoing on this species in Omani waters.

Citation: Barnett, L.A.K., Ebert, D.A. & Henderson, A. 2009. Glaucostegus halavi. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 27 November 2014.
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