Potamotrygon brachyura
| Potamotrygon brachyura | ||||||||||||
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| Potamotrygon brachyura | ||||||||||||
| ( Günther , 1880) |
Potamotrygon brachyura ( Syn . : Trygon brachyurus ) is the largest representative of the freshwater stingrays living in South America.
distribution
The species occurs in large, slow-flowing rivers in northeast Argentina , Uruguay , Paraguay, and Brazil . It is mainly found in the river system of the Río de la Plata , in the middle reaches of the Río Paraná , Río Paraguay and Rio Cuiabá . The densest population is found in the middle reaches of the Río Uruguay and in the Rio Paraná. P. brachyura prefers to be found in lagoons, oxbow lakes and in front of sandbanks.
description
Potamotrygon brachyura has small eyes and an almost circular shape. The tail, armed with a poisonous sting, is short and muscular. The body disc reaches a maximum diameter of 95 centimeters. The maximum weight of the skate is 200 kilograms. The back is covered by a black polygonal mesh pattern on a mostly light to dark brown background.
Way of life
Little is known about the widespread species. Their way of life is adapted to the water level of the large rivers: In the Río Paraná, the rays show migratory behavior when the water is low in August and September and when the water is rising in March and April. In the period between October and November they can be easily spotted and harpooned by fishermen in the bank vegetation. The reproduction rate of the animals is low. Potamotrygon brachyura is ovoviviparous . A female can give birth to up to 19 fully developed fry. The young fish, which grow slowly, initially feed on small invertebrates, later on molluscs , crustaceans and small fish. Adult animals often lie motionless and well camouflaged on the sandy bottom in flat bank regions and lie in wait for prey.
Economical meaning
Despite its tasty meat, it is rarely caught. The months December to April are considered the best fishing season. Although the export of freshwater rays from Brazil is illegal, some juveniles are available in aquarium shops. Most of them are caught in the wild. In captivity, breeding is considered difficult.
Relationship with people
On the Río Paraná, Potamotrygon brachyura is locally feared by fishermen and bathers. Due to its body color, which is adapted to its surroundings, it is difficult to make out in the murky water. If he feels threatened, he will defend himself. It can cause serious injuries by striking its tail. If arteries are hit, they can also be fatal. Its mucus also contains toxins and, if introduced into the wound, can lead to bacterial infections and, in the worst case, gangrene .
Endangerment status
The habitat of Potamotrygon brachyura is increasingly threatened by pollution and dam construction for hydroelectric systems. Thermal baths in Uruguay are often cleaned with hot water and this is then discharged into rivers, which can lead to heat shock in the species.
Web links
- Potamotrygon brachyura in the endangered Red List species the IUCN 2011. Posted by: Charvet-Almeida, P., Soto, JMR & Pinto de Almeida, M., 2009. Retrieved on 1 January 2012 Design.
- Image of a captured Potamotrygon brachyura
- Potamotrygon brachyura on Fishbase.org (English)
- Maria Lúcia Góes de Araújo, Patrícia Charvet-Almeida, Maurício Pinto Almeida, Henrique Pereira: Freshwater Stingrays (Potamotrygonidae): status, conservation and management challenges. (PDF; 78 kB)
Individual evidence
- ↑ Potamotrygon brachyura on Fishbase.org (English)
- ↑ http://insugeo.org.ar/libros/misc_14/pdf/24.pdf Lucio D. Demonte and José D. Arias: Ictiofauna de afluentes de los ríos Paraná y Uruguay en la Provincia de Entre Ríos, Argentina.
- ↑ Evoy Zaniboni Filho and Uwe H. Schulz: Migratory Fishes of the Uruguay River. ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ http://www.pescaargentina.com.ar/especies-argentinas/raya-o-chucho-de-rio.html
- ↑ Potamotrygon brachyura in the endangered Red List species the IUCN 2011. Posted by: Charvet-Almeida, P., Soto, JMR & Pinto de Almeida, M., 2009. Retrieved on 1 January 2012 Design.
