Sustainable Management and Biomass Dynamics of Prochilodus lineatus in a Mega-River Ecosystem Based on Ecohydrological Approach

Inland fisheries are vital for the livelihoods, nutrition and employment of millions of people. The small-scale fisheries in the Paraná River basin represent a complex and dynamic socio-ecological system. This study examines the sustainable management of Prochilodus lineatus (sábalo) fisheries in the middle and lower Paraná River basin, Argentina. By analysing both reported and unreported catches, we developed models to estimate maximum sustainable yield (MSY) under various scenarios. We identified that strong recruitment events in sábalo populations are primarily driven by specific hydrological conditions: summer flood pulses peaking (February–March) above 5.4 m, lasting over 45 days, followed by a minimum water level exceeding 2.2 m in subsequent years. In contrast, recruitment failures are associated with prolonged droughts and low water connectivity. The highly variable nature of recruitment and stock productivity suggests that a fixed MSY is unsuitable. Our findings also reveal that current export quotas do not adapt to these hydrological fluctuations. This research underscores the need for a dynamic, ecohydrological approach to fisheries management that incorporates both hydrological data and age structure information. This integrated long-term spatiotemporal assessment model could be used as a proxy of freshwater fisheries in large rivers of alluvial plain worldwide. Our results provide valuable insights for policymakers seeking to ensure the long-term sustainability of sábalo fisheries and the livelihoods of dependent communities.