Understanding Barotrauma in Fish Passing Through Hydro and Irrigation Structures: Tools and Techniques for Examining the Effects of Rapid Changes in Pressure

The development of hydropower and irrigation structures throughout the world has led to questions regarding the influence these structures will have on native fish populations.  For those fishes moving downstream, passage through hydroturbines and exposure to rapid changes in pressure can lead to mortality and injuries (e.g., swim bladder rupture, exopthalmia, emboli, hemorrhaging).  Based on the information learned from salmonids-focused research, there are a number of tools and techniques available (e.g., Sensor Fish, hyper/hypobaric chambers, neutrally buoyant telemetry tags) to examine the influence of rapid changes in pressure on other species.  The type of swim bladder, depth of acclimation prior to exposure, and pressure exposures experienced all can influence the rate and severity of injuries observed.  Using a suite of laboratory and field tools, the rates of mortality and injury can be measured for fishes passing through existing hydro structures.  In addition, an understanding of the physiological tolerances of relevant fishes can help direct the design of new structures.