River development for irrigation and water supply profoundly impacts global aquatic resources. The expansion of irrigation infrastructure is crucial to meet the increasing food demands of a growing global population, and it is expected to grow substantially in the next two decades. However, it is important to acknowledge that this infrastructure can adversely affect aquatic fauna, particularly fish. Fish are highly vulnerable to changes in flow patterns, obstructions in migration pathways, and limited access to vital habitats. Failure to consider and protect the migration needs of fish populations during the design and installation of infrastructure can result in significant environmental, social, and financial consequences. This issue is prevalent worldwide, as evidenced by numerous examples. Two key points to highlight are the shared challenges faced by many countries about fisheries impacted by river infrastructure development, and the potential for substantial environmental, social, and financial costs if the migration needs of fish populations are not considered and safeguarded during the design and installation of infrastructure. The expansion of irrigation infrastructure poses a threat to the diversity of freshwater fish on a global scale, as it creates barriers that impede their access to crucial nursery, feeding, and spawning habitats.
Fish passage involves movement in both directions, not just upstream migration. While there is typically a focus on helping fish move upstream past barriers, it is equally crucial to facilitate downstream movement. This is especially critical for diadromous species like eels, which must migrate downstream to reach their spawning grounds. It is essential to comprehend the impact of hydropower and irrigation systems on downstream migration to devise successful solutions.