Recovery of the Giant South American River Turtle in four decades of a network-based conservation program in the Brazilian Amazon

The Podocnemidid Amazon river turtles are the region´s most conspicuous and culturally important species. Intense exploitation led populations of the largest species, such as the Giant South American River Turtle (Podocnemis expansa), to drastic declines over time. Since 1979, the main nesting areas of the Giant South American River Turtles have been monitored and protected by the Brazilian Government through the Amazon Turtle Program (PQA). This study analyzed the PQA database from 1979 to 2022 to identify population trends in 11 major nesting areas covered by PQA. We modeled the data on the number of hatchlings for each location and the whole dataset by linear, general additive, and general linear models using Poisson and Negative Binomial distributions. In six areas, populations increased over time with statistical significance; three significantly declined, and two showed wide variation among years and no significant trend. For 43 years, there was an increase of 95% in the total sum of hatchlings from the major nesting sites included in this study. The PQA, working with partners, especially riverine communities, has been efficient in recovering populations of P. expansa in Brazil. The recent population recovery is essential to orientate conservation strategies that might be maintained or improved in areas where the population declined. The major threats causing synergistic impacts are growing in the Amazon, such as dam constructions, deforestation, mercury, and pesticide contamination. Therefore, we emphasize the need to estimate the number of nests correctly, address the impacts of different causes of embryo mortality, and maintain conservation efforts to ensure species conservation, especially in countries with no Government conservation programs.