Humane slaughter of African sharptooth catfish (Clarias gariepinus): Effects of various stunning methods on brain function

Common slaughter procedures for African sharptooth catfish (Clarias gariepinus) include asphyxiation, ice chilling and exsanguination, which may all cause substantial suffering over prolonged periods of time before death. Therefore, comprehensive evaluations potentially more humane this species are urgently needed. Here, we use a non-invasive electroencephalographic (EEG) method to assess the state sensibility in response various stunning methods (e.g. chilling, electrical stunning, followed by percussive immersion isoeugenol). Based on abolition visually evoked responses (VERs) EEG, slurry induced insensibility between 2.6 7.6 min, during exhibited aversive behaviours. Once VERs were lost, they remained absent so long as immersed slurry. Electrical (i.e. exposure ~1.7 A dm?2 at water conductivity ~997 ?S cm?1) immediately but not irreversibly. Depending duration stun from 1 10 s), either regained or within 4.9 min after completion insult. However, when s was exsanguination an slurry, sufficient humanely kill catfish. When administered correctly, manual with fish priest 36% VERs, is likely explained difficulty associated administering accurate force live struggling Catfish appeared be sedated following isoeugenol calm easy handle), yet present doses exceeding that recommended euthanasia salmonids, indicates substance suitable potential using pre-stunning sedative improving handleability reducing handling stress warrants further investigation. In conclusion, study clearly demonstrates singularly administered, none abovementioned could reliably induce and/or irreversibly without welfare implications. Yet, our findings indicate these shortcomings can resolved combination methods. This should maintain until