Proposal of a non-lethal visual census method to estimate freshwater stingray abundance
There is not a current method to estimate South American freshwater stingray’s abundance. Therefore we designed a census method and tested it in the field. It consists of making nocturnal surveys by boat in large rivers (>25m width) and floodplain lagoons of varying sizes, along transects of 100m...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Pontificia Universidad Javeriana
2016-01-01
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| Series: | Universitas Scientiarum |
| Subjects: | |
| Online Access: | http://revistas.javeriana.edu.co/index.php/scientarium/article/view/15364 |
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| Summary: | There is not a current method to estimate South American freshwater stingray’s abundance. Therefore we designed a census method and tested it in the field. It consists of making nocturnal surveys by boat in large rivers (>25m width) and floodplain lagoons of varying sizes, along transects of 100m x 10m (1000 m2). We applied this method in the Tomo River, a tributary of the Orinoco River in Colombia. 110 transects were surveyed in 200 runs. A total of 149 rays of four species were recorded: Potamotrygon motoro, Potamotrygon orbignyi, Potamotrygon schroederi and Paratrygon aiereba. P. motoro was the most abundant with a density of 0.31 individuals /1000 m2 (SD=0.5). This method gave optimal results when applied to habitats with high transparency and shallow depth (< 1m) since it permitted the identification of both adults and juveniles present. |
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| ISSN: | 0122-7483 2027-1352 |