Hydropower development in the Andean Amazon has been underestimated and will disrupt connected human and natural systems.

We mapped the inferred long-distance migrations of four species of Amazonian goliath catfishes (Brachyplatystoma rousseauxii, B. platynemum, B. juruense and B. vaillantii) based on the presence of individuals with mature gonads and conducted statistical analysis of the expected long-distance downstream migrations of their larvae and juveniles. By linking the distribution of larval, juvenile and mature adult size classes across the Amazon, the results showed: (i) that the main spawning regions of these goliath catfish species are in the western Amazon; (ii) at least three species—B. rousseauxii, B. platynemum, and B. juruense—spawn partially or mainly as far upstream as the Andes; (iii) the main spawning area of B. rousseauxii is in or near the Andes; and (iv) the life history migration distances of B. rousseauxii are the longest strictly freshwater fish migrations in the world. These results provide an empirical baseline for tagging experiments, life histories extrapolated from otolith microchemistry interpretations and other methods to establish goliath catfish migratory routes, their seasonal timing and possible return (homing) to western headwater tributaries where they were born.

Infrastructure development and overfishing in the Amazon make it imperative to define adequate scales for the ecosystem‐based management of commercial fisheries and the wetlands on which they depend. We mapped fisheries and fish ecology data from Brazil, Peru, Bolivia and Colombia to an explicit GIS framework of river basins and mainstems. Migratory species account for more than 80% of the known maximum catches of commercial fisheries across the Amazon. Of these migratory species, we nominated six long‐distance migratory fish taxa as flagship species to define the two main commercial fishery regions. The migrations of at least one goliath catfish species define a large‐scale longitudinal link joining the Andes, Amazon Lowlands and Amazon River estuary. Migratory Characiforms demonstrate interbasin wetland connectivity between nutrient‐rich and nutrient‐poor rivers over at least 2 million km2, or about one‐third of the Amazon Basin. We show that flooded forest area is the most important wetland variable explaining regional variations in migratory characiforme biomass as indicated by maximum annual fishery catches. The sustainable management of Amazon fisheries will require transnational cooperation and a paradigm shift from local community management alone to a more integrated approach that considers both rural and urban consumers and challenges, and the realistic life histories of migratory species.

Abstract. Despite large-scale infrastructure development, deforestation, mining and petroleum exploration in the Amazon Basin, relatively little attention has been paid to the management scale required for the protection of wetlands, fisheries and other aspects of aquatic ecosystems. This is due, in part, to the enormous size, multinational composition and interconnected nature of the Amazon River system, as well as to the absence of an adequate spatial model for integrating data across the entire Amazon Basin. In this data article we present a spatially uniform multi-scale GIS framework that was developed especially for the analysis, management and monitoring of various aspects of aquatic systems in the Amazon Basin. The Amazon GIS-Based River Basin Framework is accessible as an ESRI geodatabase at doi:10.5063/F1BG2KX8.

Catfishes (Siluriformes: Pimelodidae) in the Amazon River Basin serve important ecological and economic roles in structuring foodwebs, transferring nutrients and providing food resources for human populations. Large-scale developments such as construction of the Interoceanic Highway and associated proposed hydroelectric facilities could lead to alterations in river hydrology and aquatic ecosystems within Amazon headwater regions. We assessed temporal and spatial distribution patterns of catfish larvae to determine spawning location (highlands or lowlands) and larval drift patterns associated with rainfall events in the Andean-Amazon headwaters. We found significant differences in larval fish catch between transects with highest catches occurring in the Madre de Dios River, suggesting that the primary spawning habitats for these catfishes were in regions upstream of our sampling region within the Peruvian Andes. Highest larval catfish catches generally occurred near shore and in association with seasonal pulses in river flow. Based on our observations, we propose that this section of the Madre de Dios River is near the first identified spawning area for Pimelodidae species in the Peruvian Andes, and from this river reach larvae are transported downstream with each seasonal flood event with peak transport generally occurring in October, November and December. This research documents the important role the Madre de Dios Basin plays as spawning habitat for a key fish family in the Amazon River by serving as a corridor both for adult catfish spawning migrations and downstream larval fish transport. Given the critical role these catfishes play in structuring aquatic ecosystems in the Andean-Amazon region, their importance as a food resource for local people, and increasing threats to this riverine ecosystem associated with dam construction and channel modification, it is important to maintain and protect natural hydrologic conditions in the Madre de Dios to minimize losses of these ecosystem goods and services.