While it is known that changes in water temperature, especially dramatic changes, can increase stress and stress-induced mortality for many fish species, there is limited information available on the behavior of fish exposed to a thermal plume of a power generation station. The magnitude of the stress and the behavior of fish depends upon a number of factors including the species, the relative net difference in temperature between the return system and receiving water, and the physical layout of the thermal plume.
The Electric Power Research Institute (EPRI) contracted ASA to monitor the behavior of fish released into a thermal discharge over seasonal release events, in the summer (August) and in the winter (January of 2019). The summer event will expose six species of test fish to temperatures near or above critical the critical thermal maximum, whereas, the winter event will expose test fish to temperatures that may be found attractive. Acoustic tags equipped with temperature sensors were surgically implanted within each fish and then released at the surface into the discharge plume. Behavioral monitoring was accomplished by tracking tagged fish using handheld and strategically mounting stationary acoustic receivers throughout the thermal discharge to collect temperature data and fish numbers from the acoustic tags for a 14-day duration.
ASA prepared and implemented a custom field research study design to provide EPRI and it’s membership with topic-specific results to allow for informed decision making in sighting the location of a fish return system.