POPULATION STRUCTURE OF Podocnemis expansa (TESTUDINES, PODOCNEMIDIDAE) IN SOUTHERN BRAZILIAN AMAZON

PORTELINHA, T.C.; MALVASIO, A.; PIÑA, C.I.; VERDADE, L.M.; BERTOLUCI, J.

Buenos Aires

Congreso; XI Congreso Argentino de Herpetologia; 2010

Asociacion Herpetologica Argentina

Knowledge about wild populations of Amazonian turtles is still incipient, not only in Brazil but in other countries of this biome. In this study we estimated the following population parameters of P. expansa in Javaés River, in Southern Brazilian Amazon: sex ratio, age structure, spatial distribution and abundance. Fieldwork was carried out between 2004 and 2009 in a total sampling effort of 230 hours. Animals were captured by diving and net-trawling. A total of 645 individuals (266♂:379♀) were captured and marked, but only five were recaptured. Pseudo-age classes based on carapace length showed a unimodal pattern for males, but no clear pattern for females. The population was predominantly consisted by young females and adult males with a sex ratio of 1:1.4 (♂:♀). These results, suggest that this population does not have a stable structure. This could be a result of a population recovering process from a previous poaching pressure what requires population monitoring on a long-term basis. Capture success varied from 0.4 to 8.6 animals/hour independently of the method. Most animals (73.7%) were concentrated on a single river spot. Net-trawling can be an effective method for the species capture in future studies.