The effects of removal from water and death by anoxia on brain function and reflex movement were examined in conscious trout. Visual evoked responses (VERS) were measured in fish with a body temperature of 20 degrees C, 14 degrees C and 2 degrees C. On average the fish took 2.6 minutes at 20 degrees C, 3.0 minutes at 14 degrees C and 9.6 minutes at 2 degrees C to lose VERS, and 11.5, 27.7 and 197.6 minutes, respectively, to lose all movement. VERS were absent from fish anaesthetised with MS222. From a humanitarian standpoint these results indicate that fish killed by anoxia could be exposed to periods of distress or suffering, and that cooling them in ice prolongs this period.
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