Humane slaughter of farmed Arctic charr

Summary Electric stunning trials were carried out on farmed Arctic charr in northern Sweden in collaboration with the Swedish Life Sciences University. The fish were stunned in water using a range of electric field strengths and exposure durations and checked for both immediate and permanent insensibility. They were then bled and filleted to check for internal haemorrhages. A set of electrical stun parameters were identified that could be used to achieve humane, high quality, high speed harvests at an acceptable price. In collaboration with a potential manufacturer, funding is being sought to build a prototype machine to demonstrate and further test this approach. 1. Background Farmed Arctic charr are currently slaughtered using carbon dioxide narcosis or asphyxiation in ice slurry. Both methods are being phased out because they compromise the welfare of the fish. A replacement method is therefore needed. The aim of this work was to identify an alternative approach to charr slaughter and to measure the parameters required to build prototype equipment. In 1999 Silsoe Livestock Systems (then Silsoe Research Institute), in collaboration with the Humane Slaughter Association (HSA), the University of Bristol and industry partners began research aimed at developing a humane slaughter system for the UK trout industry because of welfare concerns about killing these fish. In-water electric stunning was quickly identified as a suitable and humane method since the fish do not need to be removed from water, positioned, oriented, singulated or size graded and do not need to conform to a pre-determined morphology. The result of this research was taken up by a small manufacturing company so today, most of the trout in the UK are killed humanely using this approach. Research funding from the UK government, the EC, the aquaculture industry and animal welfare charities has since facilitated the further development of this approach. Commercial equipment is now available for several fresh water and marine fish species. Consideration of the needs of the charr industry suggests that the in-water electric stunning technique could be an ideal and humane slaughter method. However before prototype equipment can be built, measurements are needed to identify the parameters required to produce immediate and permanent insensibility and to assess any potential quality problems that might be associated with the electric stunning of charr.