南部鳐鱼

The southern stingray is an active swimmer that feeds primarily at night, on a diet of invertebrates and small fishes. They feeding by flapping their wing-like pectoral fins to disturb the sand, and expose their prey (2). This bottom-dwelling species is often found singly or in pairs, except in the summer months when it migrates in schools to higher latitudes (4) (5). Very little is known about the natural mating behaviour and reproductive biology of the southern stingray. Mating stingrays are rarely encountered in the wild; during one such rare occasion, the male was observed closely following the female, and then biting her before grasping the female's pectoral fins with his mouth, and then copulating. It is thought that southern stingrays are polyandrous, as a female was observed mating with two males in quick succession (6). The southern stingray is ovoviviparous, a method of reproduction in which the egg develops within the female's brood chamber. The pups hatch from their egg capsules inside the mother, and are born soon afterwards (5). In captivity, gestation lasted 135 to 226 days, after which a litter of two to ten young were born (7).

The World Conservation Union (IUCN), considered the southern stingray to be Data Deficient due to the lack of information regarding the impacts of fishing on this species. It is therefore important that harvesting of this species in South America is monitored, and that population surveys and monitoring are undertaken (1). The Guy Harvey Research Institute is undertaking a research project on the Cayman Island stingrays. Research on behaviour, reproduction, genetics and population characteristics is being undertaken, the results of which will help inform management and conservation plans for this charismatic species (8).

The southern stingray is adapted for life on the sea bed. The flattened, diamond-shaped body has sharp corners, making it more angular than the discs of other rays (3). The top of the body varies between olive brown and green in adults, dark grey in juveniles, whilst the underside is predominantly white (2) (3). The wing-like pectoral fins are used to propel the stingray across the ocean bottom, whilst the slender tail possesses a long, serrated and poisonous spine at the base, used for defence (4). These spines are not fatal to humans, but are incredibly painful if stepped on. The eyes are situated on top of the head of the southern stingray, along with small openings called spiracles. The location of the spiracles enables the stingray to take in water whilst lying on the seabed, or when partially buried in sediment. Water enters the spiracles and leaves through the gill openings, bypassing the mouth which is on the underside (3) (4).

Inhabits shallow coastal and estuarine waters, and buries itself in sandy bottoms, and occasionally muddy bottoms, to a depth of 53 meters (3) (4).

The southern stingray occurs in the western Atlantic, from New Jersey to Florida, throughout the Gulf of Mexico, Bahamas, and the Greater and Lesser Antilles, and south to south-eastern Brazil (4). It is most abundant near Florida and the Bahamas (3).

Classified as Data Deficient (DD) on the IUCN Red List (1).

Fishing activities pose a potential threat to the southern stingray, either when caught accidentally along the east coast of the USA, or when deliberately targeted in parts of South America (1), where its flesh which is sold salted (4). The southern stingray is of considerable importance to ecotourism (4), and at well-known dive sites in the Cayman Islands, (Stingray City and the Sandbar), large numbers of southern stingrays aggregate as a result of feeding by dive operators. There are concerns that this feeding, and the high levels of interaction with humans, may be having some negative impacts on the behaviour and ecology of the stingrays (8).