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The Ray the World Forgot: Wedgefish under Threat
A neonate Bottlenose wedgefish (Rhynchobatus australiae) with unhealed umbilical scar is handled by a fisherman in a holding pond after being caught in a crab net in Chonburi Province, Thailand. Wedgefishes are aplacental viviparous: the embryos develop inside eggs that are retained in the mother’s body until hatching. The reproductive biology of these rays is for the most part still poorly understood.
The Bottlenose wedgefish glides over the sandy bottom, Malé Atoll, Republic of Maldives. These rays are most commonly seen at a depth of about 30 metres (100 feet).
Fishing crew unload plastic drums onto a commercial fishing port in Songkhla, Thailand. In the tropical Indo-West Pacific, there is substantial fishing pressure on marine resources. Trawl fisheries is a major threat to Wedgefishes, while this fishing practices are also non-discriminatory in their catches and little of the catch comprises the target species.
Wedgefishes are a common sight in the by-catch of a number of demersal fisheries, which use gear such as gill nets, long-lines, trawls, trammel nets and tangle nets. This juvenile bottlenose wedgefish, displayed for auction at a fish landing site in Ranong Province, Thailand, would not yet be mature.
Wedgefishes are highly prized species whose fins are the most sought after in the international shark-fin trade. Mature wedgefishes, at about three metres (10 feet) long, have very large fins that can fetch more than US$700 per dry kilo in the South-East Asian fin market trade. Sadly, localised population depletions have been recorded and in areas like Indonesia, where these species are targeted, fishers have had to move long distances from their home ports to locate them.
Fins from small sharks and shark-like rays are aired on drying racks at a shark processing factory in Ranong Province. According to a 2015 Food and Agriculture Organization report, Thailand has surpassed China in terms of the export (including re-export) of shark fins and specialises in small, low-quality fins. The fins of wedgefishes are marketed by traders as those of sharks, adding finning to a long list of threats to these rays’ survival.
Two juvenile Bowmouth guitarfishes (Rhina ancylostoma) are displayed for auction at a fish landing site in Ranong Province. This species is the sole member of the genus Rhina and is distinguished by knobbly ‘thorns’ on the bony ridges of its head and by its short, wide snout. These rays live in deep waters on the sea floor and are consequently often caught by commercial otter board trawlers.
The bony ridges of a Bowmouth guitarfish have been cut off, exposing part of the cartilaginous skull below. Once the thorns on the bony ridges have been removed, the rays are often finned and butchered, while the meat is salted in brine before being sold as unidentified "salted fish"
the thornns from the bony ridges of Bowmouth guitarfishes are displayed for sales at a roadside souvenir store in Kawthaung, Tanintharyi Region of the Republic of the Union of Myanmar. In Thailand these body parts are used for decorating rings and widely believed to contain magical properties. Nowadays it is illegal to sell these thorns in Thailand without special permits, where the species is legally protected, but they are still commonly available in black market.
A Bowmouth guitarfish that was found stranded is treated at thee Eastern Gulf Fisheries Research and Development Centre, Rayong, Thailand. The general public in Thailand are increasingly aware of the rarity and decline of these heavily threatened fishes.
Bottlenose wedgefish neonates are tranquillised with dexamethasone by aquatic veterinarians for transportation to a rehabilitation centre in Chonburi Province. These individuals were bought from fishers by a group of scuba divers and veterinarians. Divers usually want to help maintain wedgefish populations in Thai seas, given the limited management strategies to conserve these species in South-East Asia.
A juvenile bottlenose wedgefish is released into the sea by an aquatic veterinarian after being treated for a week. Twenty-eight other juveniles and neonates that were bought by SCUBA divers from fishers in Ranong Province died during treatment for injuries sustained in gill nets.
The story of wedgefishes is one of the belated revelations. Almost before any real light has been shone on these species, we have realised that their populations have plummeted and that they face significant threats.
Read on Save Our Seas Magazine
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