Uso da microquímica de otólitos na determinação do padrão de migração do jaraqui-escama-fina (Semaprochilodus taeniurus, Valenciennes, 1821) em rios da Amazônia Central

Abstract

Migration is a biologically complex and important event for the life cycle of many species of fish, and studies focused on this area are essential to improve the management and conservation measures for migratory species, generally of great commercial value. The migratory movements of Semaprochilodus taeniurus are still little known. There are gaps regarding the migration trajectory of this species throughout its life cycle. For this, the hypotheses were tested that specimens of S. taeniurus make migratory movements for reproductive and trophic reasons between basins or within the same basin; and that their birth location is mainly white water. In this context, this study aimed to determine the migratory movements of the commercially important species S. taeniurus, in different rivers of the Central Amazon using the 87Sr/ 86Sr ratio in the otoliths. Otoliths (asteriscus) were extracted from 17 individuals, proceeding from four basins: Amazonas, Solimões, Purus and Branco. The analysis of the 87Sr/86Sr ratio of the otoliths was performed using mass spectrometry, with plasma source and multicolector, afer a laser ablation (LAfs-MCICPMS). The main results show the presence of individuals with migrations between basins and in the basin where they were captured. During the first phase of life of the analyzed individuals were identified that most of them remain in the white waters, with the exception of one individual who presented his birth location corresponding to the same river in which it was collected, this being in the Branco river. Our study is the first to validate or use 87Sr/86Sr the otoliths for the description of the migratory behavior of the referred species. In addition, our data show that the extent of migration carried out between basins may occurs from the Amazon River to the Branco River. The present study also observed individuals being born in black water system (Igarapé). This behavior, if confirmed, is different from the one generally reported in the literature. Taken together, these results indicate that the migratory movements of S. taeniurus are much more complex than previously thought.