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Grading
Grading is a process of categorizing live crabs by size and gender to meet market
demands. The buyer may have special preferences such as size, weight and gender.
Meeting of such demands can be easier if storage is carried out in separate tanks
(Jacklin and Combes 2007a).
Slaughtering
Stunning
Crabs that are kept alive should be stunned before they are killed. This is a sensitive,
emotional, and controversial issue. Therefore, the welfare of the animal should be
taken into consideration (Jacklin and Combes 2007a). In previous studies, it has
been reported that crabs are killed or stunned by using gas or thermal shock or electric shock. In a study, it was reported that the electrical method was effective in
stunning of crabs at the commercial level and that a minimum of 220 V was needed
to stun the crabs within 1 s. It was reported that the combination of the electrical
stunning method with the thermal shock was successful to stun edible crab (Cancer
pagurus) (Roth and Grimsb 2013, 2016). In another study, it was reported that 10 s
electroshock application paralyzed blue crab (Callinectes sapidus) (Weineck
et al. 2018).
Spiking
Spiking is another method to kill crabs. They have two main nerve centres. Both
nerve centres can be destructed by spiking using a pointed pithing tool or a sharp
pointed knife.
Chilling in Air
As shellfish are cold-blooded animals, physiological functions are slowed down at
temperatures as low as 4 °C. Even if they are alive, the metabolic rate decreases by
decreasing the body temperature. However, the time required to slow down the
activity of shellfish products with this method depends on the species, size, metabolic status, and cooling rate of the organism. The method of cooling in the air is the
first stage of the two-stage killing method. This is followed by spiking that destroys
the nervous system.
Boiling
The most common method used to kill crustaceans is to leave in boiling water in a
live state. This causes them to die by causing physiological shock. During this procedure, autotomy can usually be seen. As a behavioural response, autotomy is the
2 Crustacean Shellfish
Grading
Grading is a process of categorizing live crabs by size and gender to meet market
demands. The buyer may have special preferences such as size, weight and gender.
Meeting of such demands can be easier if storage is carried out in separate tanks
(Jacklin and Combes 2007a).
Slaughtering
Stunning
Crabs that are kept alive should be stunned before they are killed. This is a sensitive,
emotional, and controversial issue. Therefore, the welfare of the animal should be
taken into consideration (Jacklin and Combes 2007a). In previous studies, it has
been reported that crabs are killed or stunned by using gas or thermal shock or electric shock. In a study, it was reported that the electrical method was effective in
stunning of crabs at the commercial level and that a minimum of 220 V was needed
to stun the crabs within 1 s. It was reported that the combination of the electrical
stunning method with the thermal shock was successful to stun edible crab (Cancer
pagurus) (Roth and Grimsb 2013, 2016). In another study, it was reported that 10 s
electroshock application paralyzed blue crab (Callinectes sapidus) (Weineck
et al. 2018).
Spiking
Spiking is another method to kill crabs. They have two main nerve centres. Both
nerve centres can be destructed by spiking using a pointed pithing tool or a sharp
pointed knife.
Chilling in Air
As shellfish are cold-blooded animals, physiological functions are slowed down at
temperatures as low as 4 °C. Even if they are alive, the metabolic rate decreases by
decreasing the body temperature. However, the time required to slow down the
activity of shellfish products with this method depends on the species, size, metabolic status, and cooling rate of the organism. The method of cooling in the air is the
first stage of the two-stage killing method. This is followed by spiking that destroys
the nervous system.
Boiling
The most common method used to kill crustaceans is to leave in boiling water in a
live state. This causes them to die by causing physiological shock. During this procedure, autotomy can usually be seen. As a behavioural response, autotomy is the
2 Crustacean Shellfish