Commercial Tilpia:
in-water electric stunning
SPECIAL THANKS: Jeff Lines and Sam Thammahong who made this project a success through COVID-19; and Cameron McClean and the team from Regal Springs who supported the installation and eventually the implementation of e-stunning in tilapia.
COLLABORATORS
FUNDERS
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GAA’s new Best Aquaculture Practices Seafood Processing Standard 5.0 requirement states:
“8.3.1 If animals are slaughtered at the processing facility, before slaughter, they shall be quickly rendered unconscious by humane means.”
For facilities to be able to meet this new requirement for humane slaughter, BAP recognised that for many it means changing their current slaughtering practices. At present most producers use carbon monoxide/carbon dioxide narcosis or hypothermic shock to “stun” fish. The OPP grant was used to support this change by facilitating trials into determine if there are commercially viable alternatives for stunning of tilapia, to improve welfare during slaughter. This project had two main objectives:
To identify electric stunning parameters that may be commercially applied to tilapia and subsequent treatments required to ensure death without recovery of consciousness.
To check that quality is not adversely affected and to compare this with fish that are stunned by hypothermic shock.
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Box stunning trial to determine the appropriate voltage and duration for the commercial stunning trial.
Trialled hypothermic shock and e-stunning side by side in a commercial processing line.
Used a single crowd, and passed fish through both methods of stunning.
Observations of welfare indicators were made throughout the process.
Subset of animals were filleted and quality scores (according to Regal Springs guide) were taken.
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From observed behavioural indicators of sensibility, fish had significantly less signs of negative/adverse behavioural responses in the electric stunned group in comparison to the group that was stunned by hypothermic shock. The data gathered shows that tilapia require exsanguination even with electric stunning as fish recovered and showed signs of sensibility if they were not bled.
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Improved welfare outcomes with the implementation of electric stunning for tilapia.
More consistent flesh quality was observed in the electric stunning groups.
Successful implementation of a commercial pilot comparing the two stunning methods.
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CHRISTINE HUYN
BELINDA YAXLEY
Our Team
Set up of the electric stunner
Figure 1: Occurrence of welfare indicators expressed as a percentage (number of fish that exhibited indicator / total no. of fish observed). Electo-stun voltage setting- high.