Crustaceans show responses consistent with signs of pain and distress. [1-6] They also have the cognitive capacity to remember, and learn to avoid unpleasant stimuli. [7-9] As a result, RSPCA Australia considers that crustaceans should be captured, handled, transported, stored and killed humanely. This is true for all crustaceans, like crayfish, lobsters, crabs, Moreton Bay bugs, and yabbies, whether they are cooked or eaten raw (sashimi).
Killing involves loss of sensibility (ability to feel pain), followed by death. For killing to be humane, either:
A variety of methods are used to capture, hold, kill and process crustaceans. How it is done depends on the species, whether it is a commercial or noncommercial operation, and what the end product is. In each case, crustaceans should be killed by the most humane method.
The legal status of crustaceans in Australia varies between different states and territories. Crustaceans are protected by animal welfare laws in New South Wales, Victoria, the Northern Territory, and the Australian Capital Territory. In some states, this only applies to crustaceans that are meant to be eaten by people. Penalties may apply if crustaceans are not treated humanely.
Shrimp are a popular type of seafood that many people enjoy eating. However, before eating shrimp they must be killed. This article will explain the most humane methods for killing shrimp that are intended for human consumption.
Why Humane Killing of Shrimp Matters
Shrimp like other crustaceans such as lobsters and crabs have nervous systems and can feel pain. Research shows that shrimp demonstrate behaviors consistent with feeling pain or distress. They try to avoid unpleasant stimuli and remember to avoid things that caused pain previously. Therefore, it is important to kill shrimp in the most humane way possible to minimize their suffering.
As consumers, we can help ensure high welfare standards for shrimp by only purchasing shrimp that have been killed humanely.
Skills Needed for Humane Shrimp Killing
Shrimp intended for sale as food should be killed by trained personnel, not sold live for consumers to kill themselves Humane killing of shrimp requires specialized skills and knowledge
Personnel responsible for killing shrimp should be trained in:
- Proper handling and care of live shrimp to minimize stress.
- Methods for stunning and killing that induce rapid insensibility.
- Recognizing signs that a shrimp is insensible or dead.
- Recognizing signs of stress or pain in shrimp.
- Proper operation and maintenance of any equipment used.
Signs a Shrimp is Insensible
Before killing, shrimp must first be rendered insensible so they don’t feel pain. Signs that a shrimp is insensible include:
- Lack of resistance to handling or manipulation of body parts.
- Lack of coordinated limb movements.
- No response when shell is tapped.
- No reaction when touched around mouthparts.
Once insensible, shrimp should be killed quickly before they can recover sensibility.
Acceptable Stunning and Killing Methods
Chilling in Ice Slurry
An effective method is to stun shrimp by chilling them in an ice slurry until insensible. Use a saltwater slurry for marine shrimp. The chilled shrimp can then be mechanically killed once insensible.
Procedure:
- Fill a container with a 3:1 ratio of crushed ice to water. For marine shrimp use saltwater.
- Add shrimp and monitor for loss of sensibility. Time required depends on size.
- Once shrimp are insensible, kill mechanically before they can recover.
Splitting
Large shrimp can be split along their length with a sharp knife to destroy the nerve cord and kill rapidly once they are stunned.
Procedure:
- Stun shrimp first by chilling.
- Hold shrimp and cut along centerline from head to tail in one quick motion.
Spiking
Smaller shrimp can be killed using spiking once they are stunned. This pierces the nerve centers.
Procedure:
- Stun shrimp by chilling first.
- Angle a pointed spike through the nerve centers behind the eyes and at the base of the tail.
In all cases, stunning should be followed rapidly by mechanical killing within 10 seconds. The nerve centers must be destroyed to ensure a humane death.
Unacceptable Killing Methods
Some common killing methods are very inhumane and cause extreme pain and distress. These must be avoided:
- Boiling, microwaving, or desiccating live shrimp
- Removing flesh or limbs from a live or insensible shrimp
- Severing parts of the body before destroying all nerve centers
- Placing marine shrimp in freshwater or vice versa (osmotic shock)
- Exposing shrimp to caustic chemicals or traumatic injury while conscious
Choosing Humane Shrimp
When buying shrimp, choose sources where humane killing practices are used, such as those outlined here. Avoid eating at restaurants that serve live shrimp. With rising concerns over shrimp welfare, more high welfare options are becoming available in stores and restaurants.
Eating shrimp does involve the death of a sentient animal. However, following these guidelines allows for killing in the most humane, painless way possible. We can enjoy shrimp while still minimizing the suffering involved in its production and death. Doing our part as ethical consumers helps drive higher welfare standards in the seafood industry.
Skills and experience required
The RSPCA Australia does not think that live crustaceans that can be eaten by humans should be sold to the public. Instead, they should be humanely killed by trained and competent personnel before purchase.
Training should include how to:
- Handle and care for live crustaceans in the right way to keep them from suffering and stress.
- induce insensibility
- recognise signs of insensibility
- recognise signs of stress
- apply the method of killing
- operate and maintain any equipment involved in the killing process.
Signs of insensibility vary from species to species but generally include: [10]
- no resistance to handling—for example, the abdomen or tail can be easily stretched out or moved, and the outside parts of the mouth can be moved without any trouble.
- no control of limb movement
- no eye reactions when the shell is tapped
- no reaction when touched around the mouthparts.
Signs of stress include:
- thrashing
- autotomy (casting off of body parts, such as limbs).
Procedure: chilling in an ice slurry
- First, put crushed ice in a insulated container like an esky. Then, add water. For marine species, add salt water that is the same salinity (salt concentration) as sea water.
- For marine species, make sure that the ratio of ice to water (salt water) is 3:1. This will give the mixture the consistency of wet cement and a temperature of about -1°C. Make sure that there is enough ice to keep the right temperature throughout the chilling process.
- Place the crustaceans in the ice slurry. Check them often for signs of not being sensitive (see “Signs of insensibility” for more information). How long it takes to make an animal insensible will depend on its species, its size, and its metabolic state. For many species, at least 20 minutes is required.
- Once the crustaceans start to lose their senses, kill them mechanically right away to make sure they don’t come back.
Large crustaceans that are adapted to very cold temperatures may be stunned by chilling in air. Because heat moves more slowly through air than through water, cooling in air takes longer than cooling in ice slurry. [3, 14, 17].