Freshwater fish are being threatened globally by the spread of river infrastructure such as dams, weirs and hydropower facilities. Fish passing downstream through these structures or in contact with turbines can be exposed to injurious hydraulic conditions, including rapid decompression, mechanical strike and elevated shear and turbulence. Significant progress has been made in understanding these impacts on migrating salmonids in North America, with the goal of optimising the design and operation of hydropower to improve fish survival. However, the problem is global, and many of the world’s largest and most diverse freshwater fisheries (e.g. Mekong and Amazon Basins) currently threatened by the expansion of hydropower remain unstudied. In other areas (e.g. Murray-Darling Basin) small-scale hydropower operations are being explored on existing irrigation networks, with limited understanding of the potential impact. A team of researchers from Asia, North America, South America, and Australia are collaborating on a joint effort to tackle this global problem. The research includes the use of autonomous sensor technology to quantify hydraulic stress at infrastructure, migration studies to determine likelihood of exposure, and laboratory studies to simulate rapid decompression and elevated shear to determine operational ranges required to minimise injury and mortality. International collaborative research using a standardised approach has a large role to play in improving the environmental sustainability of irrigation and hydropower practices and redressing current and predicted declines in global fish populations.