Estudo da ictiofauna no reservatório da Pedra do Cavalo Rio Paraguaçu Geolândia Bahia Brasil

Abstract

The Paraguaçu River has been used for research on the ichthyofauna due to its rich diversity and the changes suffered in its course, such as the construction of several dams to supply water, causing several environmental problems, causing the disappearance of several ichthyic species. The present work aims to study the ichthyofauna in the Pedra do Cavalo Reservoir, Geolândia, Cabaceiras do Paraguaçu, Bahia, through the biological aspects of the species such as the weight length relationship, the population structure in classes, the analysis of the reproductive aspects of the Trairá (Hoplias malabaricus), through the evaluation of gonadal structure, gonodosomatic index and gonadal condition factor. In the period from May 2019 to February 2020, the collection period ended with the months of March and April 2022, due to the pandemic period. From these data, analyzes of the population structure and abundance were carried out using Excel 2019 software. In the period of one year of collection, 288 individuals were captured, divided into three orders, six families, seven genera and nine species. There was a greater abundance of native species in the region, highlighting the species Hoplias malabaricus, occurring in greater numbers and frequently in all months of collection. It was also possible to relate abundance with rainfall in the period, with greater relative abundance being observed in the wettest months and a lower abundance in the dry period. For the weight-length relationship, it was possible to analyze six species due to the sample number, where six of these species presented a negative allometry, with a condition factor consistent with this relationship, showing that these populations have young individuals, displaying strategies linked to stages of growth advanced ecological succession of a community, surviving in environments where competition is high. The species Serrassalmus piraya presented a value close to the negative allometric, showing that the growth and weight are in their ideal. The reproductive studies of this work were carried out based on the species Hoplias malabaricus as it was the only species that showed frequency throughout the period of the project. Macroscopic observation showed that the ovaries are elongated and filiform, being located in the upper portion of the abdominal cavity, separated in the anterior portion, uniting to empty into the genital orifice, flank the swim bladder, attached to the side walls by a strong membrane. We conclude, therefore, that the study was important for the knowledge of the ichthyofauna of the region influenced by the Pedra do Cavalo Hydroelectric Reservoir, highlighting the relative abundance of native species, which was greater than 80% of the captured species.