Halavi Guitarfish: Glaucostegus halavi

Family: Glaucostegidae
Common name(s)

Halavi Guitarfish.

Identification

A large guitarfish with a relatively wide, short, pointed snout with a rounded tip. Rostral ridges joined along most of snout length. Rostral cartilage posterior margin sharply demarcated. Eyes small. Snout length 6.3-7.8 x orbit length. Spiracles with two short, widely separated skin folds. Nasal flaps barely extend posteriorly beyond nostril opening.
Anterior margins of disc straight or weakly convex. Pectoral apices broadly rounded. Skin covered in small denticles, appearing rough along rostral ridge, between eyes, on shoulders, and along centreline. Small thorns present around eyes, single larger thorn on each shoulder, and in a continuous row along medial ridge from nape to tail.
Tail robust, slightly longer than disc length. Dorsal fins large and well separated, with narrowly rounded apices. Caudal fin triangular, without a defined lower caudal lobe.

Colour

Dorsum yellowish to greyish-brown and unmarked. Rostral cartilage pale. Ventrum white.

Size

Maximum length 171cm. Size at birth ~29cm.

Habitat

Tropical seas. Benthic on sandy substrates and sea grass. From very shallow water to at least 100m.

Distribution

Northwestern Indian Ocean. The halavi guitarfish is present from Kenya to India, including the Arabian Sea and Red Sea.

Conservation Status

CRITICALLY ENDANGERED

There is a high level of fisheries resource use and increasing fishing pressure across the range of the Halavi Guitarfish, and as a result, targeted and incidental fishing effort is placing significant pressure on all giant guitarfishes in the Indo-West Pacific. Where wedgefishes and giant guitarfishes have been targeted or exploited as incidental catch, severe declines, population depletions, and localized disappearances have occurred. Severe population reduction in the Halavi Guitarfish is inferred from actual levels of exploitation, as well as several historical accounts and contemporary datasets from Iran, Pakistan, India, Thailand, and Indonesia (and while some of these datasets are outside the range of the Halavi Guitarfish, they can be considered representative of population reduction throughout the Indo-West Pacific). Furthermore, rapid declines have been documented in landings of the Halavi Guitarfish in the United Arab Emirates, and while some local trawl bans would likely benefit the species, actual levels of exploitation remain significant across the region. It is inferred that the Halavi Guitarfish has undergone a >80% population reduction over the last three generations (30 years) and it is assessed as Critically Endangered A2bd.

Citation

Kyne, P.M. & Jabado, R.W. 2019. Glaucostegus halaviThe IUCN Red List of Threatened Species 2019: e.T161408A124479984. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T161408A124479984.en. Downloaded on 25 May 2021.

Reproduction

Aplacental viviparous. Litter size ~10.

Diet

Diet consists mainly on benthic invertebrates.

Behavior

Enters very shallow water to feed. In the Red Sea, the halavi guitarfish reproduces from May to October.

Reaction to divers

Usually skittish.

Diving logistics

The halavi guitarfish is seen fairly regularly by divers and snorkelers in the Red Sea. For example at Gorgonia Beach off Marsa Alam, Egypt.

Similar species

Sharpnose Guitarfish Distinguished longer, more acutely pointed snout.