A feasible method for humane slaughter of eel (Anguilla anguilla L): electrical stunning in fresh water prior to gutting

• Published in: Aquaculture Research
• Main Authors: Lambooij, E., van de Vis, J.W., Kuhlmann, H., Muenkner, W., Oehlenschlaeger, J., Kloosterboer, R.J., Pieterse, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2002
• Subjects: Eel; Electrical stunning; Fresh water; Slaughter; Anguilla anguilla
• Online Access: https://research.wur.nl/en/publications/a-feasible-method-for-humane-slaughter-of-eel-anguilla-anguilla-l; https://doi.org/10.1046/j.1365-2109.2002.00677.x

It was observed that farmed eels could be rendered unconscious and insensible instantaneously by passing an electrical current through fresh water. The general epileptiform insult on the EEG was characterized by a tonic/clonic and an exhaustion phase. After stunning, the ECG (electro-cardiogram) revealed fibrillation. The electrical stunning parameters were on average 194 ± 4 V and 0.636 ± 0.040 A/dm2 for 1.6 ± 0.4 s. Within a confidence level of 95L taking into account the number of animals with a reliable EEG (n = 29), at least 93 f all eels are effectively stunned in fresh water by an average current of 0.636 ± 0.040 A/dm2. The behaviour of groups of five eels, which were able to move freely in the water was observed before and after stunning with 50 V and 0.17 A/dm2. After 3-s stunning, two eels were turned upside down. They changed to a normal position after 10 and 13 s respectively. Subsequently, all eels were very active in swimming behaviour and stopped swimming after 75 s. When stunned for a longer duration, all eels were turned upside down and stopped breathing for a limited period of time. In the last experiment the eels were stunned in fresh water (500 ?S) with a voltage of 200 V for approximately 1 s, which was followed by 50 V for 5 min. As soon as the stunning started the water was de-oxygenated by flushing nitrogen to kill the eels by suffocation during the period of unconsciousness and insensitivity. The oxygen saturation decreased from 74 ± 10 to 23 ± 11 t 22 °C. After stunning no brain activity and no responses to pain stimuli were observed on the EEG. The heart rate increased (P < 0.05) after stunning, which was followed by a significant decrease. Only 1 out of 18 eels returned partially from upside down to a normal position 2 h after stunning; however, the eel did not respond to pain stimuli in behaviour. The developed stunning procedure can be recommended for humane slaughter of 50-kg batches of eels.