Food quality is increasingly becoming a global concept
as suppliers and retailers become larger and fewer. Food should be responsibly
sourced, safe and traceable to the farm.
In addition, the ethical aspects concerning food production, such as
protection of the environment and animal welfare have been identified as
important issues for consumers. Most countries have legislation covering the
welfare of mammals and birds, however few have detailed legislation applying to
fish, although this is rapidly changing.
Farmed fish welfare at slaughter is of special
importance as this has potential to cause significant, stress, pain and
suffering. A slaughter method is considered to be humane when unconsciousness
is induced immediately by stunning and is irrecoverable. The slaughter of wild
fish represents an area of growing concern because most fisheries do not
consider slaughter of their fish as a step in the process, but more a
by-product of the capture and chilling process, with fish dying of anoxia
before or during chilling without bleeding. This is slowly changing as
fishermen and retailers gain knowledge in the benefits of applying modern
welfare and quality practices.
There is a
wide variety of slaughter techniques used between and within farmed fish
species with some methods very clearly superior to others,
and performance is easily measurable from KPI’s like rigor time, gaping,
bloodspotting, yield and shelf life. Common methods include the following, with
some combined:
·
Exposure to air
·
Ice slurry
·
Bleeding
·
Gutting
·
Anaesthesia
·
Carbon dioxide
·
Electrostunning
·
Ike Jime (Spiking)
·
Percussive stunning
In
general, the slaughter methods that are slower result in more movement by the
fish that is generally perceived as being aversive. The only movement seen
using the faster methods, (i.e. percussive stunning and spiking) occurs during
pre-slaughter handling. While some believe that there is a developing consensus
that fish feel pain, and respond to this pain with aversive movements, this is
yet to be decisively proven. However, there is a strong perception of concern
from people viewing slaughter operations when they observe fish exhibiting
aversive behaviour. The perception of fish retailers reflect this attitude and
many have set standards for suppliers that focus on minimizing stress and
suffering. In the UK, the RSPCA have developed Welfare Standards for Farmed
Atlantic Salmon enabling salmon farmers to receive Freedom Food accreditation,
and the Freedom Food logo on their products identifies them as conforming to
these standards. These standards state that:
“The
method of killing used must rapidly, and without pain and distress, render the
fish insensible, until death supervenes. An efficiently applied percussive blow
is the only permitted killing method at present. This method is highly
effective when applied properly. Humane mechanical percussive devices are now
available commercially and these must be used in preference to a manual percussive
blow for slaughter (except emergency killing). “
Mechanised
percussive stunning and bleeding is creeping into certain wild cod fishery
operations and the fishermen and buyers are amazed at the quality difference.
It is only a matter of time before it becomes commonplace with wild fisheries
catching cod, haddock, saithe, salmon, etc. In the meantime, the early players
are reaping the rewards for being industry leading.
Substantial
progress has been made in the development of commercially viable pneumatic
stunning machines and these are now widely used by the farmed salmon industry,
and are also present in cod, yellowtail, basa, channel catfish, trout, and
barramundi slaughter operations. Fish can now be directed to machines without
manual handling, in water, up to the point of stun. The quality and welfare benefits
of this technology, and in many cases logistical improvements, have attracted
interest from many farmed and wild fishery operations, and this method of
slaughter shows most promise at present to develop and spread over a range of
fish species and locations.
