Entendendo mortandade de peixes: uma abordagem experimental com liberação e recuperação de carcaças

Abstract

Fish mortality events are largely linked to anthropogenic activities, causing population reductions and altering entire community dynamics, leading to significant economic losses. In neotropical regions like Brazil, there is a lack of studies enabling more precise estimates of the number of dead fish, especially in large river systems. This dissertation aims to comprehend the dynamics of fish carcasses and, consequently, estimate the number of affected fish. To achieve this, an experiment releasing Oreochromis niloticus carcasses into the Paraopeba river was conducted over 12 months. The outcome of this dissertation is a scientific article presenting the results obtained from this experiment. The findings indicate that less than 5% of the carcasses were detected, highlighting underestimation in counting, particularly for small fish. The time elapsed after carcass release proved crucial for accurate estimates, with over 70% of carcasses recovered within the first two days. River flow, water temperature, and rainfall were relevant variables affecting recovery, directly influencing the distance traveled by the carcasses. Thus, underestimation in estimates, especially for small fish, is emphasized, underscoring the importance of swift actions after mortality events. It is proposed to conduct more comprehensive studies, considering different species and environments, emphasizing the need for solid foundations for conservation and mitigation policies.