PNNL

Abstract

When fish pass downstream through river infrastructure, such as dams and weirs, barotrauma may occur due to rapid decompression. In severe cases, barotrauma may lead to mortality. Different species likely respond differently to these decompressions. Therefore, to predict barotrauma for a specific species, surrogate species may not be a valid approach, and it may be necessary to examine each species individually. For this study, Australian bass and carp gudgeon were exposed to a range of rapid decompressions using hyper/hypobaric hydro-chambers and examined for injuries and mortality. Rapid decompression data from these two fish species, in addition to previously examined Murray cod and silver perch were evaluated to determine which injuries were highly associated with and likely to predict mortality. Dose-response logistic regressions models were developed for each species to predict injury and mortality over a range of rapid decompressions. These models are valuable for estimating injury and mortality rates for fish passing though river infrastructure and can be applied to specific sites where pressure profiles have been developed. Applying these models to current and future infrastructure can provide important insight into what measures or design alterations may be necessary to reduce negative impacts of infrastructure on fish populations.