Chilling is Best
September 2007
If you're the squeamish type who feels bad about killing your crayfish for
dinner, Biosecurity New Zealand has some pearls of wisdom about humane
ways to kill crustaceans.
Crayfish and crabs are classified as animals under the Animal Welfare Act
1990, and it is an offence to kill an animal in a way that causes it
"unreasonable or unnecessary pain or distress"
The latest edition of Biosecurity NZ magazine recommends humane ways of
killing your catch.
Biosecurity NZ says that despite appearances, many crustaceans have quite
elaborate nervous and sensory systems, and their nerve cells appear similar to
our own when viewed under a microscope.
Because of this, it is not possible to kill crustaceans by trauma to a central
nervous system, such as a blow to the head, as it is with vertebrates.
Drowning a crustacean from the sea in fresh water is not recommended, as it
causes severe osmosis stress and causes the meat to become too soft.
Boiling is also not recommended, as the animal's nervous system is still
functioning when it is immersed into the water. Nerve function needs to be
reduced for humane killing.
Chilling your crustacean is the simplest way to kill without damaging the
edible parts of the body.
Chilling can be done by:
- Placing the animal in a slurry of ice in salt water.
- Placing the animal in a refrigerator set at 2 to 4 degrees.
When the animal is fully chilled, it stops moving, does not respond to
handling and is insensible. It can then be killed by the following methods:
1. Head spiking: the animals are spiked between the eyes.
2. Chest spiking: the animals are spiked through the chest wall
from the underside.
3. Splitting: the body is split along it's length with a knife.
So, in future, bear a thought to the humble crayfish's feelings when you are
about to prepare a feast to impress your friends.
Pauline & Stuart