Warning, it's a catfish! Novel approaches are needed to study the effects of rapid decompression on benthonic species

Auditorium

Barotrauma due to rapid decompression has been recorded as the most common injury among fish captured in the tailrace of hydropower dams in Brazil, with catfishes representing the majority of them. Nevertheless, studies investigating barotrauma on catfish are scarce, with the majority determining dose-response curves and thresholds of pressure changes for nektonic species as salmonids. Experiments conducted with Pimelodus pictus showed that the current hypo-hyperbaric chambers used to study barotrauma in nektonic species have limitations when applied to benthic groups. The negative buoyancy showed by the catfish prevent the definition of the acclimation pressure of the fish prior to exposure to decompression and, therefore, hinder calculation of the ratio of pressure change (RPC). RPC has been considered the main factor explaining the likelihood of barotrauma on fish. Since its calculation is restricted for benthic species, new approaches deemed to be needed to complement barotrauma studies with this group. We aimed to discuss the limitations observed for studies with benthonic species and present potential methods to overcome them. The diversification of approaches for barotrauma studies with benthonic species is critical to provide information for the development of mitigation and new turbine designs that would improve protection of this group.