Red stingray  (Dasyatis akajei)

Classified as Near Threatened (NT) on the IUCN Red List (1).

Like other stingrays, the red stingray has a flattened body and a long, whip-like tail bearing a strong, saw-edged stinging spine on the upper surface, used as a defensive weapon (2) (3) (4). Generally orange-brown above and white to pale pink below, with yellowish margins (2) (4), the body and large pectoral fins form a flattened, diamond-shaped disc, with a moderate snout at the front and a pair of single-lobed pelvic fins at the back. Like other stingrays, this species lacks dorsal and caudal fins (2) (3) (5). The gills and mouth are located on the underside of the body, with the eyes situated on top, just in front of openings known as spiracles, through which the stingray can take in water whilst lying on the seabed. Water enters the spiracles and is passed out over the gill openings, bypassing the mouth (2) (5).

The red stingray is believed to be endemic to the Northwest Pacific Ocean, occurring around Japan, Taiwan and China (1) (2) (6). Its possible presence in the Western Central Pacific is uncertain (1).

Most stingrays live on or near the ocean bottom in inshore waters (2). The red stingray is reported to occur in shallow coastal waters and bays, and over the continental shelf (1) (2) (6).

The red stingray is a top predator in its ocean bottom habitat, feeding mainly on crustaceans and small fish, and also taking various worms and molluscs (2) (3) (6). However, very little is known about the life history of this species. Male red stingrays are thought to reach sexual maturity at a disc width of around 35 centimetres, and females between 50 and 55 centimetres (6). Interestingly, at maturity the male and female develop markedly different teeth, with those of the female being virtually flat, and those of the male developing pointed cusps. No large differences in diet have been detected, and it is thought that the differences in the teeth are related to mating behaviour, with the male using the teeth to grip onto the female’s pectoral fins during copulation (6).

Like other stingrays, the red stingray is likely to be ovoviviparous, a method of reproduction in which the eggs develop and hatch inside the female and are born live (2) (3) (5). In most stingrays, litter size ranges from two to six young, born after a long gestation period of up to twelve months (2). However, the red stingray may have smaller litter sizes than most, reportedly giving birth to just one pup per litter (1).

The red stingray is valued for its meat, and is caught commercially in the coastal waters of Japan. It is also commonly taken as bycatch in other fisheries, and this, combined with the strong commercial fishing pressure, appears to be leading to population declines (1) (2) (6). The low reproductive rate of this species makes it particularly vulnerable to overfishing (1), with populations potentially taking a long time to recover from any losses.

There are no specific conservation measures known to be in place for the red stingray. Recommended conservation actions for this commercially important but relatively little-known stingray include the collection of data to accurately assess its population levels, and the development and implementation of management plans for all rays and sharks in the region (1).

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

To find out more about the conservation of sharks and rays 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/