When they have reached slaughter weight, farmed Atlantic salmon may be removed from their sea pens through large pipes and transferred to special catching and slaughter boats that sit alongside the pen. Alternatively, well boats are used or the whole pen is slowly towed towards shore where fish are transferred to a slaughter plant on shore.
Before slaughter, fish may be fasted for a few days in order to reduce the oxygen demand required to digest their food. By reducing this oxygen demand the fish are better able to cope with the catching and slaughter process.
The catching and slaughter process keeps fish in water as long as possible before they are stunned using a percussive blow to the head. Subsequently, the unconscious fish are bled and immersed in ice slurry for transport to processing plants where they are gutted, washed and processed into fresh, frozen or smoked product.
The RSPCA Approved Farming Scheme Standard for farmed Atlantic salmon provide the requirements for rearing, handling, transport and slaughter. The standards for slaughter require that fish are stunned and therefore unconscious before any further processing is carried out.