Methods for the Assessment of Fishways (Upstream Fish Passage)

Fragmentation of rivers by manmade barriers has impeded the ability of riverine fish to move freely. Barriers can be improved by fishways that can partially mitigate the negative impacts by acting as aquatic corridors. Effective fishways require knowledge about the physiological and spatial demands of fish species, but the existing knowledge largely derived from laboratory settings. Evaluating fishway performance is needed for optimisation of their hydraulic design and positioning. Qualitative methods include trapping, electrofishing, and camera observations to estimate the number of individuals passing (effectiveness). For quantitative assessment, the study of individual fish behaviour can identify fishway sections in need of improvement and estimate associated efficiencies. This can be accomplished by telemetric techniques such as PIT tagging, radio, and hydroacoustic telemetry.