RESUMO
Techniques were developed to determine which life stages of fish are vulnerable to barotrauma from expansion of internal gases during decompression. Eggs, larvae, and juvenile hatchery-reared white sturgeon (Acipenser transmontanus; up to 91â days post hatch; d.p.h.) were decompressed to assess vulnerability to barotrauma and identify initial swim bladder inflation. Barotrauma-related injury and mortality were first observed 9â d.p.h., on the same day as initial exogenous feeding. However, barotrauma-related injury did not occur again until swim bladder inflation 75â d.p.h. (visible at necropsy and on radiographs). Swim bladder inflation was not consistent among individuals, with only 44% being inflated 91â d.p.h. Additionally, swim bladder inflation did not appear to be size dependent among fish ranging in total length from 61 to 153â mm at 91â d.p.h. The use of a combination of decompression tests and radiography was validated as a method to determine initial swim bladder inflation and vulnerability to barotrauma. Extending these techniques to other species and life-history stages would help to determine the susceptibility of fish to hydro turbine passage and aid in fish conservation.