tic charr
12
Pre-harvest treatment
Food withdrawal
13
Crowding
13
Removal from water
14
Anaesthetics
15
Pumps and pipes
15
Brailling
15
Hand-nets
16
Killing methods
Principles of humane slaughter
17
Staff training
17
Percussive stunning
18
Priest
18
Mechanical percussive systems - manual feed
19
Mechanical percussive systems - automatic feed
19
General considerations
20
Carbon dioxide narcosis
21
Live chilling
21
Death in ice slurry
22
Death in air
22
Gill cut
23
Electrical stunning
24
Recommendations
25
The future
27
Conclusions
28
Advancing Aquaculture: Fish Welfare at Slaughter
Contents Advancing Aquaculture: Fish Welfare at Slaughter
1
For the past five and half years I have been employed by the Humane Slaughter
Association (HSA) as a Technical Officer.
The HSA is the only registered charity to specialise in the welfare of food animals
during marketing, transport and slaughter.
As a non-campaigning organisation the HSA works in a practical and rational way
to develop welfare standards through technology transfer, education and advice to
industry and government.
The HSA uses up-to-date knowledge and practical experience to write best practice
guidelines for the industry and regularly advises retailers and others on their codes
of practice. My job involves regular liaison with industry and government on animal
welfare issues and improvements.
Over the last three years I have been involved in the British aquaculture industry,
gaining an understanding of the practical requirements for commercial slaughter
systems and providing advice on humane methods of slaughter appropriate to the
situation. In addition to the UK work, I have also been involved in assessing
alternative slaughter methods used in Norway and New Zealand.
This work has led to production of educational material about the humane killing
of fish and various articles for publication and presentations at technical
conferences.
I would like to thank the Winston Churchill Memorial Trust for its generous funding
of this study tour and its support whilst planning and carrying out this project. In
addition thanks are given to the Humane Slaughter Association (HSA) for its
support. Without the support of both of these organisations this trip would not have
been possible and fish welfare at slaughter may still have been an issue on the
back burner in many companies and countries.
I also would like to extend my gratitude to all the people, too numerous to mention,
that helped organise the study tour and spend their time detailing current industry
practices and the implications of these to fish welfare.
Special thanks are given to those people who went beyond all expectations and
spent many hours arranging visits and encouraging the industry to be involved in
this project. These people, in particular Melissia Struthers (CAIA), Fred Conte (UC
Davis California), Antonio Campos Mendoza (University of Stirling) and Alberto
Ramírez (Fundacion Chile), all made a significant contribution to the success of
this project and also helped keep me positive (and sane!) throughout the trip.
This study has been invaluable in gaining a sound understanding of slaughter
systems and the practical implications of such methods in a wide range of
circumstances.
Specific information from this study is confidential, but the knowledge from this
work has been used to produce guidance notes on the humane killing of salmon and
trout and at the request of various parties best practice guidelines are currently
under development.
Acknowledgments:
Personal background As over 30% of the global seafood harvest is
already produced from aquaculture, and
predictions made in 2000 forecast that global
fish consumption will rise 25% by 2030 (3kg
increase per person), it is easy to understand
why aquaculture is such a rapidly expanding
industry. With such an increase in demand,
new sources of cultured fish are required,
especially as customers want quality
products all year round.
In addition to this there is increasing pressure
on wild fish stocks and the cost of catching
from the sea is rising. This cost is seen both in
environmental and financial terms. The
environmental cost of the wild catch is
continuously rising as stocks are depleted; the
resultant changes in sea life affect the natural
balance of the oceans. It is also suggested by
the FAO that the actual cost of catching wild
fish can be 25% more than the value, a figure
which is offset by government subsides.
Although still a relatively new industry in
commercial farming terms, aquaculture has
already made huge changes since it became
a significant commercial venture over 30
years ago. In this time the industry has grown
from small individual farms to multi-national
companies which are streamlined and
increasingly efficient at producing millions of
animals annually.
One of the primary aims of aquaculture is to
produce a consistent and safe product with
full traceability, reliably and, in accordance
with customer demands. With this aim it is
clear to see how aquaculture can fit the above
demands and help resolve the potential lack
of supply, not only for food fish, but also
improve other industries such as those that
rely on fish, ie animal feed and leisure. As the
industry progresses, it is essential that it
grows responsibly and reacts to consumer
requirements in order to develop suitable
products that are required.
Although there is over 20 species of fish
farmed, salmon and trout are commonly
farmed in the UK. For these reasons these
species have been the main focus of recent
research into humane methods of slaughter
and practical improvements. However, as the
numbers of fish have increased so has the
number of species farmed. New species are
continuously being identified for their farming
potential as new developments and scientific
understanding allows production of many
species that were not previously economically
viable.
One of the difficulties faced by the
aquaculture industry is that recommendations
are not necessarily universal or transferable
between species or even the countries
involved. This makes technology transfer
between species very difficult and setting
guidelines very complicated, ie what works in
one country may not be legal in another or
may not even be technically feasible in
another. This means that throughout the
industry the level of knowledge varies greatly,
depending on the length of time that particular
species has been farmed.
In response to the growing scientific opinion
that fish feel pain and can suffer, careful
consideration is now being given to the
methods of slaughter employed around the
world and in particular in the UK. These
methods are also influenced by product
quality and the positive relationship this has
with humane handling and slaughter.
Whilst the debate about pain perception in fish
is ongoing, it is generally accepted that
farmed fish should have their welfare
protected and be treated humanely whilst kept
in aquaculture systems. The consideration of
welfare is not only ethically correct, but
commercially sound: humane treatment is
important to realise potential growth rates and
product quality. Although terrestrial animal
welfare has been studied for many years,
similar studies for aquaculture are still in their
infancy. However, over the past few years the
aquaculture industry has actively striven to
advance this knowledge base; supporting
both scientific and practical research which
has led to improved technology, knowledge
and production procedures.
Introduction
Advancing Aquaculture: Fish Welfare at Slaughter
2 The welfare of an animal can be defined as 'its
state as regards its attempts to cope with its
environment'. This environment includes
physical conditions, social influences,
predators, parasites or pathogens interacting
with individual animals. Fish maintain a
constant internal environment; when this is
threatened a range of reactions take place to
elicit physiological (production of adrenaline,
noradrenaline and cortisol) and physical
(increased heart rate, vigorous muscle
contractions) changes to reinstate the balance
as soon as possible; this is widely known as
the stress response. When the response is
successful the physiological reactions subside
and the internal environment is restored within
hours. However, if the challenge is not
removed/avoided the response is prolonged
and it can be assumed that the welfare of that
animal is compromised.
In-depth knowledge of species-specific
welfare requirements and relevant signs of
the stress response are essential for correct
welfare assessment. As a result, welfare is
often reviewed using the five freedoms
principle which take into account the
psychological needs in addition to the
physical. These include, freedom from:
hunger and thirst; discomfort; pain, injury and
disease; fear and distress, and freedom to
express normal behaviour.
Whilst some principles for basic requirements
and responses are applicable to all species
and transferable, there are also important
species differences. Every species needs to
be considered on an individual basis.
Consideration of the nature of the welfare
'problem', its duration and effect on individual
animals must be taken into account during
welfare assessments. Fish have the capacity,
within limits, to adapt to acute stressors;
however, exposure to chronic