Humane Stunning and Slaughter of Decapods

One of the most common questions we are asked is - what is the most humane way to kill a crab or a lobster?

 

To humanely slaughter a crab or lobster, they must firstly be stunned effectively, followed by mechanical killing, before they are cooked. Therefore, it is not possible to humanely slaughter decapods at home. The steps required for humane slaughter must be carried out by a trained professional. Read more about these steps below.

Crustacean Compassion believes that decapod crustaceans should only be stunned using methods that result in either instantaneous death (i.e. less than one second) or instantaneous insensibility to pain and distress, that is maintained until death occurs. Killing should always be carried out by trained and competent practitioners, and never by amateur consumers.

Please be aware: the following information contains graphic descriptions.

Humane Method of Stunning

Electrical stunning

Crustacean Compassion believes that electrical stunning is the best option currently available for rendering decapods insensible. This must be done immediately before a swift and effective killing method (on its own, electrical killing is not a humane method of slaughter). Evidence indicates that electrical stunning can deliver a quick, effective and humane stun to decapod crustaceans including crabs, lobsters, crayfish and shrimp, when appropriate electrical parameters are applied for the species (1, 2, 3, 4). Further research is currently being conducted into, for example, the most effective parameters for different species.

 

Electrical stunning equipment

Electrical stunning should only ever be done with approved, specialist equipment. Whilst we do not endorse any particular device, there are machines already on the market.

 

The Crustastun is a restaurant-scale device used by renowned chefs such as Giorgio Locatelli at Locanda Locatelli, Raymond Blanc at Le Manoir, and Nigel Bloxham at the Crab House Café in Dorset. A version is also available for large-scale processors.

We believe that this new Crustastun system is an important advance from an ethical point of view, and have discovered that it also enhances texture and flavour
- Raymond Blanc OBE. 

The STANSAS, a Norwegian commercial dry stunner for fish, has also been adapted for the more humane stunning of edible crabs in line with Norwegian animal welfare regulations.

Meanwhile, Ace Aquatech has won an award for an in-line fish stunner that can also be adapted for the more humane slaughter of decapod crustaceans, and Hilton Seafoods has won a Compassion in World Farming award for a shrimp stunner.

Humane Methods of Slaughter After Stunning

Effective stunning, which is guaranteed to last throughout the entire process, must take place prior to slaughter, regardless of the slaughter method used.

Mechanical methods of slaughter (spiking or splitting)

Skilled, competent application of certain methods of mechanical killing of decapod crustaceans that effectively destroy their nerve centres can result in relatively swift (though usually not instantaneous) death.

 

Such methods include the ‘spiking’ of crabs or the ‘splitting’ of lobsters and similarly shaped species. These different techniques must be used due to contrasting layout of these species' ganglia. A lobster's ganglia runs through the length of the body, so they must be cut fully down the longitudinal midline on the underside to ensure destruction of all ganglia. Spiking of the head alone of lobsters is ineffective and should never be performed. We recommend that mechanical killing is done after electrical stunning.

 

Due to the skill required to achieve accurate and speedy spiking/splitting, if not done correctly these methods cause severe suffering. Mechanical killing should only be applied by trained, competent practitioners, immediately after the animals have first been effectively electrically stunned, and before they are cooked.

If you have further questions about this, please contact us: info@crustaceancompassion.org

Boiling after stunning

The boiling of effectively stunned decapods as a method of slaughter is humane, as long as the stun lasts throughout the entire slaughter process. Please read the below section on inhumane stunning and slaughter to find our more about why live, conscious boiling should never be done. 

Inhumane Methods of Stunning and Slaughter

Many of the current methods used to prepare decapods for consumption are actually ineffective and inhumane.

 

Chilling

For example, chilling decapods (in a fridge, freezer or on ice) is sometimes mistakenly used in an attempt to stun them before slaughter. However, whilst this process may make the animal appear still, there is no evidence to suggest that chilling induces unconsciousness or anaesthesia, rather than just paralysing them (6). In fact, chilling beforehand increases the time taken for them to lose consciousness and die in boiling water. Therefore, decapod crustaceans should not be subjected to chilling for the purposes of stunning or killing.

Boiling

Similarly, boiling alive is a commonly used method of slaughter, but is not humane. When boiled alive, lobsters and crabs often thrash, try to escape, and shed their limbs, known to be a sign of stress. It can take up to 3 minutes for them to lose consciousness in boiling water (5), which is an unacceptable length of time to suffer.

The following methods are inhumane and should not be used on decapod crustaceans:

  • Live, conscious boiling

  • Chilling in the fridge, freezer or in an ice slurry

  • Dismemberment of live animals

  • Freshwater drowning 

  • Electrical killing

  • High pressure processing

  • High salt solution

  • CO2 gassing

  • Chemical anaesthetics

To find out more about these methods, head to our policy page.

Good Practice

There are many examples of good practice that is already occurring in the food industry. As well as the restaurants cited above that are using the Crustastun, Waitrose stun their UK-caught brown crabs and lobsters and Tesco stun their UK- caught, own-brand, brown crabs and lobsters.

Our responsible Fish and Shellfish policy states that all UK caught crab and lobster should be humanely stunned prior to cooking (…) the preferred method is electrical stunning using commercial machines

- Customer Services, Waitrose

All of our Tesco Own Brand UK crab and lobster is humanely stunned prior to slaughter

- Aquaculture Manager, Tesco

But with no legal guidelines, there is no obligation for the food industry to treat crabs, lobsters and other decapod crustaceans humanely, either in storage or during slaughter. This is why we work with food businesses to implement changes to their practices; and we put pressure on the Government to make the necessary changes to the law.

Industry

If you work in industry and have good practice that you would like to share with us or if would like to discuss anything you've seen here in more detail, we'd love to hear from you. Get in touch via email: info@crustaceancompassion.org

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Find out what is required for an animal to be considered able to feel pain, and how decapods meet these requirements.

For more information on our position on key welfare issues, check out our animal welfare policies and position statements.

Image by Alejandro Alas

Take action now to get these vulnerable animals protected in UK animal welfare legislation.

References

1. Roth, B., & Øines, S. 2010. Stunning and killing of edible crabs (Cancer pagurus). Animal Welfare, 19(3), 287-294.

2. Roth, B., & Grimsbø, E. 2016. Electrical stunning of edible crabs (Cancer pagurus): from single experiments to commercial practice. Animal Welfare, 25, 489-497.

3. Fregin, T. and Bickmeyer, U, 2016. Electrophysiological Investigation of Different Methods of Anesthesia in Lobster and Crayfish. PLoS ONE, 11(9): e0162894.doi.10.1371/journal.pone.0162894

4. Weineck, K., Ray, A., Fleckenstein, L., Medley, M., Dzubuk, N., Piana, E., Cooper, R. (2018). Physiological Changes as a Measure of Crustacean Welfare under Different Standardised Stunning Techniques: Cooling and Electroshock. Animals, 8(9), 158; https://doi.org/10.3390/ani8090158.

5. Roth, B., & Øines, S. 2010. Stunning and killing of edible crabs (Cancer pagurus). Animal Welfare, 19(3), 287-294.

6. Mood, A., 2014. Welfare during Killing of Crabs, Lobsters and Crayfish. Fish Count. http://fishcount.org.uk/welfare-of-crustaceans/welfare-during-killing-of-crabs-lobsters-and-crayfish (accessed on 1 July 2021).

7. Roth, B., & Øines, S. 2010. Stunning and killing of edible crabs (Cancer pagurus). Animal Welfare, 19(3), 287-294. ix Gardner, C. 1997. Options for humanely immobilising and killing crabs. Journal of Shellfish Research 16(1), 219-224