This project aims to evaluate the home range and population parameters of Phrynops williamsi individuals inhabiting the Parque Estadual do Tainhas (Tainhas State Park), located at the municipality of São Francisco de Paula, State of Rio Grande do Sul, Brazil. To do so, we will use 10 radio-transmitters that will be put on males and females. Juveniles will not receive the device due to their smaller body size. Furthermore, population parameters will be evaluated through the capture-mark-recapture method. Individuals will be captured with 10 fyke nets. Overall, what we want to know is how many individuals compose a population, and how much space they need to survive. Specifically, what we will accomplish is: (1) Unravel the home range size of individuals; (2) Compare the home range size of males and females; (3) Monitor the temporal and spatial displacement of individuals; (4) Assess seasonal variations of displacement; (5) Estimate the population abundance through the robust design; (6) Estimate survival rates of males, females and juveniles; (7) Assess the population structure; (8) Establish the free river area in-between dams needed to maintain viable populations of the species; (9) Support species conservation strategies in southern Brazil.