Clubnose guitarfish  (Glaucostegus thouin)

The clubnose guitarfish is classified as Vulnerable (VU) on the IUCN Red List (1).

The characteristic heart-shaped silhouette of the clubnose guitarfish (Glaucostegus thouin) is the result of a somewhat bizarre feature of its development, where the head is fused on each side to enlarged pectoral fins. Named for its elongated, club-like snout, the clubnose guitarfish has a flattened, slender trunk with rounded pelvic fins and two large dorsal fins, while the long, stout tail bears an imposing, shark-like caudal fin (3) (4). The body is covered in tiny, tooth-like scales which reduce drag in the water and make swimming more efficient. The clubnose guitarfish is generally brownish in colour, sometimes varying from yellow-brown, grey-brown, greenish or black, and is usually white underneath (4) (5).

The clubnose guitarfish is found in inshore waters, spanning from the Red Sea, to Malaysia, Singapore, Thailand, Vietnam, Indonesia, New Guinea and Japan. Unconfirmed reports suggest that the clubnose guitarfish may also inhabit waters in the Mediterranean and Suriname (1) (2) (6).

A bottom-dwelling (benthic) species, the clubnose guitarfish is typically found over soft and sandy substrate at less than 60 metres depth (1).

Relatively little is known about the biology of this species, although it is thought that the clubnose guitarfish feeds on small fish and invertebrates that live on or near the sea bed (1). Most guitarfish in the Rhinobatidae family are suction feeders, where prey is sucked into the mouth and swallowed whole (4) (5) (6). The breeding behaviour of the clubnose guitarfish is not well documented; however, it is likely to be ovoviviparous (5) (6).

The clubnose guitarfish is threatened by both small scale and commercial fisheries where it may be targeted for its valuable fins, or caught accidentally as bycatch. As so little is known about the biology and habitat requirements of the clubnose guitarfish, it is difficult to assess the impact of other potential threats for this species; however, it is likely that human activities, destructive fishing practices, habitat degradation and pollution will all have an increasingly negative impact on survival (1) (6).

Much more research is required on the population structure, biology and ecology of the clubnose guitarfish, in order to determine how fishing practices, habitat destruction and other pressures are threatening the species. In addition, management plans must be developed in order to facilitate the conservation and sustainable management of this species (1). 

View information on this species at the UNEP World Conservation Monitoring Centre.

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.

To find out more about the conservation of rays and sharks, see:

• Save Our Seas Foundation:
  http://www.saveourseas.com
• IUCN Shark Specialist Group:
  http://www.iucnssg.org
• Shark Research Institute:
  http://www.sharks.org
• Shark Trust:
  http://www.sharktrust.org