Experimental comparison of fish mortality and injuries at innovative and conventional small hydropower plants - raw data

Resolving the controversy about hydropower is only possible based on reliable data on its ecological effects, particularly fish welfare. Herein, we propose a comprehensive assessment of conventional and innovative hydropower using a data set of 52 250 fish. The effects of hydropower on fish were most harmful at sites with Kaplan turbines, showing £ 83% mortality. Innovative hydropower, often termed 'fish-friendly', caused £ 64% mortality. Our findings suggested that the runner peripheral speed, number of turbine blades, turbulence and gas oversaturation at turbine outlets were the most important factors. Synthesis and Applications: To reduce the impact of hydropower on fish, site-specific characteristics such as head drop, bypass options and river-specific species composition need to be more intensively considered in optimal turbine technologies and operation modes.