The process of ‘stunning’ means the animal becomes completely insensible to pain and distress. This insensibility should be instantaneous and must be maintained until death occurs.
Currently, electrical stunning is the only humane method of stunning with research demonstrating a total loss of central nervous system activity and responsiveness to sensory stimulation [1-4]. When carried out using approved, specialist equipment and the correct, species-specific criteria is met, electrical stunning can deliver a swift (within one second), effective and humane stun to crabs, lobsters, crayfish and shrimps.
However, other methods are practiced throughout the industry. These include chilling (below), the use of chemical anaesthetics, and CO2 gassing, all of which have the potential to cause significant welfare concerns.
 Roth, B., & Øines, S. (2010). Stunning and Killing of Edible Crabs (Cancer).
 Roth, B., & Grimsbø, E. (2016). Electrical Stunning of Edible Crabs (Cancer Pagurus): From Single Experiments to Commercial Practice.
 Fregin, T., & Bickmeyer, U. (2016). Electrophysiological Investigation of Different Methods of Anesthesia in Lobster and Crayfish.
 Weineck, K., Ray, A.J., Fleckenstein, L.J., Medley, M., Dzubuk, N., Piana, E., & Cooper, R.L. (2018). Physiological Changes as a Measure of Crustacean Welfare
under Different Standardized Stunning Techniques: Cooling and Electroshock.