Halavi's guitarfish (Glaucostegus halavi)

Fishes · Rays · Guitarfish

Halavi Guitarfish

Glaucostegus halavi (Forsskål, 1775)

syn. Raia halavi, Raja halavi, Rhinobatos (Scobatus) halavi, Rhinobatos halavi, Rhinobatus halavi, Scobatus halavi

up to 1.7 m1-100 mCITES IICritically Endangered

899

It eats things that live under the sand, and finding them is the hard part.

A guitarfish spends the day buried with only its eyes and spiracles above the surface. When it hunts it moves slowly across the flat with its snout close to the bottom, and what it is doing is reading: the underside of the snout and head carry the ampullae of Lorenzini, jelly-filled canals sensitive to electrical fields of a few nanovolts per centimeter. Every living animal leaks a field from its muscles and nerves, and a crab or a shrimp under three centimeters of sand is invisible, silent and completely obvious to a ray.

When it finds one it pins the sand with its body, digs with the snout and takes the animal into a mouth on the underside, where flattened crushing plates rather than teeth do the rest. Crustaceans are most of the diet.

This is the guitarfish you are most likely to meet here, on sand flats and in lagoons, sandy brown and usually invisible until it moves off. It is also Critically Endangered: the whole family is fished heavily across its range, and shallow sand is the easiest place in the sea to set a net.

The genus. Glaucostegus Bonaparte 1846 - glaucus (bluish-green or gray) + stegus (to cover). ETYFish

The species. Glaucostegus halavi (Fabricius 1775) - Arabic name for this fish. ETYFish

How to recognise it

long pointed snout, narrower than in the clubnose guitarfish
plain sandy brown above, usually half buried with only the eyes showing
shark-like tail, gills underneath the body
up to 1.7 m

Why it's threatened

Biological resource use

Intentional use: (subsistence/small scale) [harvest] · Intentional use: (large scale) [harvest] · Unintentional effects: (subsistence/small scale) [harvest] · Unintentional effects: (large scale) [harvest]

Globally, giant guitarfishes are subject to intense fishing pressure on their coastal and shelf habitats that is unregulated across the majority of their distributions. Giant guitarfishes are captured in industrial, artisanal, and subsistence fisheries with multiple fishing gears, including gillnet, trawl, hook and line, trap, and seine net and are generally retained for their meat and fins (Bonfil and Abdallah 2004, White and Sommerville 2010, Moore 2017, Jabado 2018). There is a high level of fisheries resource use and increasing fishing pressure across the range of the Halavi Guitarfish, and demersal coastal fisheries resources have been severely depleted in significant areas of the Indo-West Pacific, including India (Mohamed and Veena 2016).

In general, fishing effort and the number of fishers has increased in recent decades across the range of this species, with demand for shark and ray product increasing over the same period due to the shark fin trade (Chen 1996, Jabado et al. 2017). In the Red Sea for example, the number of traditional boats tripled from 3,100 to 10,000 from 1988 to 2006 (Bruckner et al. 2011), and in the Indian state of Gujarat, the number of trawlers increased from about 6,600 in the early 2000s to 11,582 in 2010 (Zynudheen et al. 2004, CMFRI 2010, Jabado et al. 2017). Most countries have significant fishing fleets operating in coastal waters e.g. Oman (19,000 artisanal boats) and Pakistan (2,000 trawlers) (Jabado et al. 2017).

Sharks and rays, including giant guitarfishes, are often targeted and now heavily exploited across the region by net and trawl fisheries and increasing fishing effort has put significant pressure on all giant guitarfish species in the Indo-West Pacific. Furthermore, the high value of fins is driving retention and trade of giant guitarfishes globally (Moore 2017, Jabado 2018). The Halavi Guitarfish is landed throughout its range (e.g. Spaet and Berumen 2015, Henderson et al. 2007, Jabado 2018) and several countries within the distribution of this species rank among the top 20 shark fishing nations globally, specifically India, Pakistan, and Iran (Lack and Sant 2011).

The shallow, inshore soft-bottom habitat preferred by the species is threatened by habitat loss and environmental degradation (White and Sommerville 2010, Moore et al. 2012, Jabado et al. 2017, Moore 2017). In the Arabian Sea and adjacent waters, dredging and coastal land reclamation has increased in recent years and has resulted in almost total loss of mangroves in some areas, such as Bahrain (Sheppard et al. 2010, Jabado et al. 2017).

Threat classification from the IUCN Red List.