|Scientific Name:||Potamotrygon magdalenae (Duméril, 1865)|
Taeniura, magdalenae Duméril, 1865
Trygon hystrix Müller & Henle, 1841
|Taxonomic Notes:||This species has been mistaken for P. yepezi from Lake Maracaibo (Rosa 1985). It is also pointed out as being easily mistaken for P. falkneri, P. signata and P. castexi in the ornamental trade (Ross and Schäfer 2000).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Lasso, C., Mesa-Salazar, L., Sanchez-Duarte, P., Usma, S. & Villa-Navarro, F.|
The Magdalena Freshwater Stingray (Potamotrygon magdalenae) is a small freshwater stingray (adults 19-21 cm DW) that is restricted to the Magdalena and Atrato River basins in Northern Colombia. The biological information available indicates that it has low fecundity (2-4 pups) and feeds on insect larvae, but further data are needed on its life history. This species is in the ornamental trade and is a by-catch species in other fisheries but no other information is available. Monitoring and specific management for the ornamental trade and by-catch are recommended. Habitat maintenance and conservation are also required conservation measures. Due to its low fecundity and threats, this species is presumed to be declining in abundance. However, it has a wide range and is frequently caught. Hence, it is listed as Least Concern.
|Previously published Red List assessments:|
|Range Description:||This species is restricted to the drainages of some rivers in Northern Colombia, including Magdalena, Cauca, San Jorge, and Atrato rivers. It has not been registered in the Sinú River. In the Santander Department, it has been found in Barrancabermeja (ciénaga El Llanito, ciénaga San Silvestre), Lebrija (Bodega Central, río Lebrija), Puerto Wilches (humedales de Puerto Wilches), and Sabana de Torres (ciénaga de Paredes, caño Peruétano) (Castellanos-Morales et al. 2011). Its type locality is Río Magdalena (Duméril 1865).|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||It is considered abundant in the floodplain lakes of the Magdalena River basin (Mójica et al. 2012). However, its population is presumed to be decreasing.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This species inhabits both headwaters and lower drainages of some rivers within its distribution range (Galvis et al. 1997), and both in the main riverbed and floodplain lakes (Mójica et al. 2012). It occurs in turbid waters, with sandy and muddy substrates, murky and shallow, slow-current waters (Dahl 1971, Galvis et al. 1997, Mójica et al. 2012).|
Most reproductive biology information available comes from a single research study carried out by Teshima and Takeshita (1992). It is a viviparous aplacental species that develops only one embryo in each uterus (Teshima and Takeshita 1992). Its observed fecundity varied between 1 and 3 embryos (Mójica et al. 2012). Ramos-Socha (2010) pointed out a larger proportion of mature females between January and March, with a peak in March and a decline around May. The female gestation takes place afterwards in November and in April and May (Mójica et al. 2012). Dahl (1971), in a general study of the fish in Northern Colombia, mentioned that this species reached maturity with less than 25 cm of disc width. The information available suggests that this species reaches sexual maturity at a small disc width size and presents a low fecundity. Since most potamotrygonids present a defined reproductive period (Charvet-Almeida et al. 2005), it is possible that Teshima and Takeshita (1992) could not observe this due to the short length of their sampling period.
It feeds on detritus (dead organic matter) and larvae (Galvis et al. 1997), occasionally aquatic invertebrates and insects (Villa-Navarro 1999), larvae and adults of the family Polymitarcidae (Ramos-Socha 2010), fish, crabs, tadpoles, snails, insects and organic matter (Dahl 1971, Lasso et al. 2011, Mójica et al. 2012).
|Use and Trade:||
In the Magdalena basin, the young are captured for ornamental purposes and due to the collapse of fisheries of other species, adults of the Magdalena Stingray are captured for subsistence (Lasso et al. 2011, Mójica et al. 2012).
The main threat to this species is its capture for ornamental use and subsistence as food (Lasso et al. 2011), water pollution from agrochemical, domestic (sewage) and mining activities, wetland dessication and deforestation. Dam construction has also been identified as a threat because it creates barriers to the species' dispersal and interrupts the genetic flow (Mójica et al. 2012).
In 2004, this species was entering the ornamental trade (Gonella 1997, Ross and Schäfer 2000) without any specific regulation and monitoring. No information was available about how many specimens were exported and to what extent this might represent a threat for the species. It is currently the most exported ornamental fish and it is estimated that 60-70% of the exported rays belong to this species (Perdomo-Núñez 2005). According to INCODER (Instituto Colombiano de Desarrollo Rural), 14,621 individuals, captured from Ciénaga Grande de Santa Marta, dam del Gúajaro, small swamps or lagoons near the airport of Barranquilla and the Prado dam (Tolima), were exported in 2009 (Mójica et al. 2012).
Informal reports indicate that this species is also caught as by-catch in fisheries that target some bony fish of economic value in the river basins where P. magdalenae is found. Many individuals by-caught in the Atrato basin are killed because of fear of injuries from the stinger (Perdomo-Núñez 2005, Mójica et al. 2012).
Other threats for this species are not well known but considering the main known threats for other potamotrygonids (included the ones cited for P. yepezi by Mojica et al. 2002) it is expected that it is susceptible to water pollution of different origins (agricultural, industrial and sewage pollution mainly), mining, infrastructure development and human disturbances. As in other parts of the North region of South America, it is expected that persecution of this species also takes place.
This species is listed Near Threatened (NT) in the Red Book of Freshwater Fish of Colombia (Mójica et al. 2012). In 2002, Mojica et al. considered it as a Vulnerable species (VU) but no details were given concerning the criteria for the selection of this specific status. It is included in the National Action Plan for the conservation and management of sharks, rays and quimaeras of Colombia (Caldas et al. 2010) as a species of very high action priority, in relation to its fishing, trade and distribution. Base-line studies are required to acquire more information regarding the life history aspects of this species. More information about the trade is also needed in order to implement management plans, trade management and specific legislation to guarantee that catches are sustainable (Caldas et al. 2010). Also, regulation of the exportation through quotas based on scientific criteria of abundance in its natural environment is needed (Mójica et al. 2012). The designation of priority conservation areas (for example, fishing reserves) based on management plans shared between fishermen, middlemen and exporters and ex situ study programs are also recommended (Mójica et al. 2012).
By-catch captures should also be monitored and quantified in order to determine to what extent target (bony fish) fisheries represent a threat. Habitat maintenance and conservation should also be considered since freshwater elasmobranchs are more susceptible to impacts due to their more restricted distribution in comparison with their marine counterparts (Araújo 1998, Charvet-Almeida 2001, Charvet-Almeida et al. 2002). Mojica et al (2002) indicated the need for habitat protection, base-line studies and population evaluation for P. yepezi, which are probably valid recommendations for P. magdalenae. Public awareness is desired to minimize persecution, which probably occurs (as in other places where freshwater stingrays are present).
|Citation:||Lasso, C., Mesa-Salazar, L., Sanchez-Duarte, P., Usma, S. & Villa-Navarro, F. 2016. Potamotrygon magdalenae. The IUCN Red List of Threatened Species 2016: e.T161385A61472512.Downloaded on 21 October 2017.|
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