LAUSR

Recent studies have identified patterns of genetic organization during schooling in the reproductive period of several Neotropical freshwater migratory fish. However, population segregation during non-reproductive periods is still unknown for most species. In this study, we investigated the genetic structure of populations of Salminus brasiliensis, a high-value large migratory freshwater fish, sampled during the non-reproductive season. We analysed 89 adults from Uruguay River Basin (Brazil) collected during the two consecutive non-reproductive periods, and assessed the genetic diversity levels using eleven microsatellite loci. Our results showed that populations are genetically structured, suggesting these fish can remain grouped likely due to a cooperative behaviour, not related to reproduction, in a typical shoaling behaviour. Besides, we found high genetic diversity for S. brasiliensis from the Turvo State Park area, highlighting the importance of this conservation unit as a relevant area for maintaining the genetic variability of S. brasiliensis in the Uruguay River.