Bowman et al. CO2 data

Part 1 monitored time to loss of visual indicators in rainbow trout during CO 2 stunning under field conditions at 14°C, 8°C, and 2°C. Analysis showed that time to loss of visual indicators increased as temperature decreased, with significant differences in time to loss of equilibrium between 2°C and 14°C, and significant differences between all temperatures in time to loss of eye-roll reflex and ventilation.

In part 2 trout were equipped with external non-invasive electrodes for measurement of EEG and exposed to repetitive light stimulation to evoke responses (VERs) indicative of brain function. This was done before and after exposure to CO 2 saturated water in a laboratory environment at 10°C. EEG recordings showed a poor relationship between visual indicators of consciousness and loss of brain function, with VERs continuing up to 3.5 min after ventilation was lost and up to 6.5 min after the fish lost equilibrium.