Document type : online prepublication of article in Aquaculture Research
Authors: Jennifer Bowman, Nicole van Nuland, Per Hjelmstedt, Charlotte Berg, Albin Gräns
Preview: A two-part experiment was conducted to determine whether visual indicators of consciousness such as equilibrium, eye-roll reflex and ventilation are reliable for evaluating whether CO 2 stunning of rainbow trout (Oncorhynchus mykiss) is humane. In part 1, the time taken until the loss of visual indicators in rainbow trout during CO2 stunning was monitored under field conditions at 14, 8 and 2°C. Here, we clearly demonstrate that it takes longer for visual indicators to disappear as temperature decreases, with significant differences in the time taken until the loss of equilibrium between 2 and 14°C, and significant differences between all temperatures in the time taken until the loss of eye-roll reflex and ventilation. Collectively, these results show that cold-water temperatures prolong the time taken until loss of consciousness and that visual indicators are insufficient for determining when sensibility is lost in rainbow trout during CO 2 stunning.
