Genetic evidences of non-reproductive shoaling in the freshwater fish Salminus brasiliensis

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.