As previously reported, Fresh Studio partnered with Can Tho University and Ace Aquatec to conduct research on the efficacy of a prototype in-water electric stunner on catfish (Pangasius hypophthalmus) in Vietnam.
Monitoring recovery of stunned fish
The project aimed to verify the parameters set by the in-water electric stunner's developers (Ace Aquatec) and the University of Stirling under lab conditions. The study focused on the duration of the stun, recovery time of the animal, and stress levels experienced compared to traditional slaughter methods.
In brief, four treatments were tested: Control - C1 (asphyxiation for 5 minutes before killing), Control 2 - C2 (percussive blow), Electric Stunning -T1 (Stunned by Ace Aquatec in-water stunner before killing) and Observed - T2 (Electric stun and then placed in tank for observations).
Pangasius are a notably resilient fish, even regarding electrical stunning. Similar trials with African Catfish, showed that consciousness was regained within 82 seconds and a full recovery made if not immediately killed.
The results on consciousness showed similar recovery times, with eye roll occurring after 68 seconds, ventilation after 76 seconds and swimming movement after 138 seconds.
The blood samples results showed higher levels of cortisol C1 compared with T1 and C2. Cortisol levels in fish dispatched or stunned immediately were seen to have much lower levels, indicating lower stress levels. While this did not show a significant difference between traditional methods and electric stunning, it did highlight the impact of poor handling prior to slaughter.
Texture analysis showed that fish held in baskets (asphyxia) before dispatch showed weaker texture, again reinforcing a need for improved handling techniques prior to slaughter to improve product quality.
The research is summarised in the following video.