PNNL

Abstract

Barotrauma, injuries sustained following rapid decompression, occurs in many different fisheries applications. Previous attempts to quantify barotrauma in fish have been limited by hyper/hypobaric system function. Further, field studies are often confounded by covariates. The Mobile Aquatic Barotrauma Laboratory (MABL) was designed to address these limitations. Specifically, this testing facility allows the user to evaluate similar complex pressure scenarios that migrating juvenile salmonids are exposed to following turbine or spillway passage. In addition, factors including total dissolved gas, temperature, and acclimation pressure are controlled automatically with this mobile lab. In this paper we also present a case study where negative and neutrally buoyant juvenile Chinook salmon were exposed to simulated hydro-turbine passage (STP). Gill emboli, swim bladder rupture, mortality, and internal haemorrhaging were used as end points. The severity of the decompression profile and the fish’s ability to gain neutral buoyancy were used as predictor variables. We determined that fish that achieved neutral buoyancy during a 16 hour acclimation period had a greater risk of injury following STP than negatively buoyant conspecifics. This research solidifies the need to allow fish to become neutrally buoyant when assessing barotrauma and mortality in field and laboratory applications. Finally, MABL can be configured to examine a variety of different species and pressure profiles, and physical parameters in a controlled environment.