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

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