Fishers’ local ecological knowledge indicate migration patterns of tropical freshwater fish in an Amazonian river

The local ecological knowledge (LEK) of fishers may help to fill the knowledge gaps about migration of tropical fish. We investigated fishers’ LEK on migratory patterns of seven fish species along 550 km of the Tapajos River, in the Brazilian Amazon. We interviewed 270 fishers individually in four stretches of this river. The interviewed fishers indicated that three fish species do not migrate over long distances, while four fish species perform migrations, usually longitudinal migration from downstream to upstream reaches. Fishers also mentioned an increase in size of a large catfish species in the upstream stretches of the studied river, indicating the potential occurrence of spawning adults there. These results from fishers’ knowledge indicated that planned dams in the upstream reaches of the Tapajos River will threaten migratory fishes, small-scale fisheries and food security. Fishers’ LEK on fish migration contributed to raise testable biological hypotheses about fish spawning and feeding grounds, as well as the occurrence of distinct populations along the river. The analysis of the LEK of many fishers at several sites over a broad range is a cost-effective source of information on fish migration, supporting environmental impact assessment, fisheries management, and conservation in this and other tropical rivers.