Revisitando as migrações laterais no sistema Lago do Rei, Ilha do Careiro, AM

Abstract

In areas of floodplains (várzea), periodically flooded by rivers, the ichthyofauna is diverse, abundant, and adapted to live in these environments. In floodplain systems, connectivity between floodplain habitats is critical for migratory species. Fishes perform longitudinal migrations, along the main river channels. Lateral migrations occur between the main river channel and the floodplain, depending on the water level. In the 1980s, lateral migration patterns in the Lago do Rei, Ilha do Careiro floodplain system were described. After almost four decades, we returned to the same place to assess the current state of lateral migrations. The objective of this work was to compare the lateral migration data from 2020-2022 with those from 1985-1986. We hypothesized that the migratory species would show the same patterns as observed previously, in 1985 and 1986. We also started with the premise that these species would make more than one lateral movement per hydrological cycle. We used gillnets exactly like the ones used in 1985-1986, and calculated the CPUE to compare with past data. Additionally, analyzes were carried out on the biology of migratory species, such as body condition, reproduction and tendency of migratory movements. Biological data were related to the hydrological regime. A total of 10 species were considered migratory in the 2020-2022 collections, three of which were not sampled in the past. Although several species occurred in both periods, their abundance and frequency varied. The patterns of migratory behavior in the Lago do Rei System are similar when observing the reproductive data and the trend of movements varied in some species. Body condition is displayed during migration periods and varied significantly between periods for some species. The causes that may have influenced the differences were discussed. As Lago do Rei, with its fishing potential, is the main source of livelihood for the riverside inhabitants of this locality, a study on the management of fishing stocks is recommended. It is expected that biological information, such as that of the present study, may serve as a basis for future monitoring.