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Fish Welfare
Slaughter methods in sea fisheries
"Some were still thrashing; some were too
tired; many were vomiting up their guts, their eyes bulging from
the pressure change. Some of these fish may have been struggling
in the nets for up to 24 hours. After a few minutes, their gill
arches were slit and they were thrown into the next bin, where
they twitched and gasped, slowly bleeding to death."
They
die slowly by Dawn Carr, director PETA UK
Gill nets
Gill nets are walls of plastic monofilament netting, which may
be set at or below the surface, on the seabed, or at any depth
inbetween. Gill nets are static gears (fixed nets) that catch
fish as they attempt to swim through the net; fish are caught
if they are of a size large enough to allow the head to pass through
the meshes but not the rest of the body. As it attempts to back
out of the net, the fish becomes entangled or trapped by its gill
slits. As it struggles to escape forwards, the fish becomes trapped
by the thin mesh, which presses or slices into the flesh. Because
gill nets are set and then left unmonitored ("soaking"),
trapped fish may suffer for many hours or even days. Many fish
die from strangulation, blood loss and/or suffocation before the
net is retrieved. Dead or alive, the trapped fish are ripped out
of the netting by hand ("stripping").
Tangle nets resemble gill nets but are slacker, shorter
and have less flotation. This results in a looser-hung net that
entangles species rather than "gilling" them. Trammel
nets are a wall of net divided into three layers. An inner
fine-meshed net is sandwiched between two outer, larger meshed
nets. The net is anchored at the base and floated by the headline,
allowing it to hang vertically. The inner net is looser than the
outer ones, ensuring that the fish become entangled within it
(MCS 2006).
Long-lining
This method is used to capture both demersal and pelagic fishes
including swordfish and tuna. It involves setting out a length
of line, possibly as much as 50-100km long, to which short lengths
of line, or snoods, carrying baited hooks are attached at intervals.
A single long-lining boat may deploy hundreds of thousands of
baited hooks. The lines may be set vertically in the water column,
or horizontally along the bottom. The size of fish and the species
caught is determined by hook size and the type of bait used.
In common with other hook-capture methods (trolling, pole and
line fishing also known as bait boat fishing, hand-lining, and
jigging for squid), long-lining relies on impaling the fish on
a hook, which is often barbed. Once hooked, the fish and bycatch
animals such as marine mammals, seabirds and turtles, variously
drown or bleed to death in the water, or struggle for hours until
the boat returns to reel them in. Large fish such as swordfish
and yellowfin tuna, each weighing hundreds of kilograms and struggling
to free themselves, are pulled toward the boat and hauled aboard
by fishers sinking hand hooks and grapnels into the animals' fins
or sides. Many of the fish are still alive on deck and are clubbed
to death or else have their gills sliced open to bleed them to
death.
Trawling
Various methods of pelagic/mid-water and demersal/bottom trawling
are used in fisheries above the continental shelf and beyond in
the deep-sea. They all involve towing gears which "herd"
fish towards the mouth of a trawl net; as the fish become exhausted
they are funnelled down and collected in the narrow sleeve known
as the "cod-end". The first fish in the trawl net are
dragged along for hours and may suffocate as other fish pile in
on top of them, making it impossible for their gills to extract
oxygen from the water. The fish become crushed under the weight
of the accumulating catch.
On being hauled to the surface, deepwater fish and bycatch species
experience decompression due to the extreme pressure drop. This
can cause the fishes' eyes to balloon out, their stomachs to be
forced out through their mouths and their swim bladders to rupture.
Surviving fish are tossed together with the dead onto ice where
they slowly suffocate and freeze to death. It is not unusual for
fish to be sliced open and gutted whilst still alive.
Almost everything that is hauled out of the sea as bycatch is
returned dead or injured, due to crushing, drowning, suffocation
and changes in pressure.
Deep-sea trawling
The first lengths of blue and yellow nets come up and are wound
on to drums with deep flanges. Their meshes are studded with grotesque
black heads, jaws agape to show ragged teeth. These are black
scabbard fish… These fish, with their heads poking through
like throttled serpents, are merely stray specimens and are wound
with the nets on to the drums…
Finally the "cod ends" appear: the last part of the nets holding
the main catch. Side by side they come up the ramps, each bulging
with about two tonnes of assorted bodies. Ropes are slipped around
each net and the cod-end fastenings are released. Twin iron hatches
open in the deck. At a signal the cod ends are hauled into the
air and four tonnes of dead and dying sea creatures slither into
the fish hold below and the hatches slam shut. At once the men
set about readying the trawls for shooting again…
The complete turnaround has taken 70 minutes. The deck is scattered
with stray bodies: pale dying crabs, fish mangled in the nets'
meshes, the odd starfish.
Now the crew goes below to the gutting line. A conveyor belt carries
the fish from the hold, men standing in line to deal with them
as they pass. This catch is indeed mainly of scabbard: a tedious
fish from the men's point of view because these slippery individuals,
numbering in the thousands, have to be both beheaded and gutted.
There are several other species mixed in, including grenadiers
(which are simply tailed), a few blue ling (easily gutted) and
a couple of dozen Portuguese dogfish, known in the industry as
siki shark…
Like the crabs, the siki shark seem more resistant to the gross
shock of being brought up from a kilometre below and several still
thrash or twitch among the heaps of corpses. Many of the fish
show acute signs of depressurising. Their eyes bulge and their
swim bladders protrude grotesquely from their mouths. One siki
shark I noticed in the hold was lying on its back among the bodies,
lolling with the ship's roll. Suddenly, with a convulsive shudder,
it gave birth. The baby was about 15cm long, black, its eyes little
luminous beads of the same shade and intensity as its dying mother's.
In the next three minutes it was joined by a further five siblings,
blindly burrowing among the dead heaps of fish in a hopeless search
for the sustaining sea.
James Hamilton-Paterson onboard the Scottish deep-sea trawler
Atlantic Challenge (Troubled
Waters, Guardian 28-3-2002)
Welfare of farmed fish
Traditionally, animal suffering was subjectively measured, i.e.
humans projected their perceptions of suffering onto animals.
However, we have now moved to a system of objective measurement
based on scientific research into pain and stress in animals.
Across the EU, the emphasis in new legislation has changed from
simply prohibiting cruelty to prescribing conditions which promote
good animal welfare practices (Magee 2006).
Intensive fish farming, whereby large numbers of fish are confined
in a small area, causes serious welfare problems that need to
be addressed urgently to prevent further widespread suffering
(CIWF 2002).
Slaughter methods used on
farmed fish
Pre-slaughter handling – the stress of slaughter can start
well before the fish reach the stunner. Salmon can have difficulty
in adapting quickly enough to being hauled to the surface of deep
cages. Cages can be 5-20m deep. Fish at a depth of 20m experience
3 times the atmospheric pressure at the surface. When a fish is
brought to the surface, it must regulate its swim bladder.
Starvation – farmed fish are normally starved for about
7-10 days before slaughter. This period can be extended to 12-14
days in the winter. Scottish Quality Salmon currently insist that
its scheme’s producers starve fish before slaughter for a minimum
of 7 days. It is said that this is to empty their gut and minimise
the risk of the flesh becoming contaminated when gutted. However,
gut clearance only takes 24-72 hours. Farmed fish are conditioned
over months and years to expect frequent and plentiful feed. To
suddenly cut off that feed is highly likely to be detrimental
to their welfare. The Farm Animal Welfare Council recommended
that starvation periods must be kept to a minimum and should not
normally exceed 48 hours for trout and 72 hours for salmon (FAWC
1996). Starvation periods longer than 48-72 hours are excessive
and are highly likely to be detrimental to the welfare of the
fish. In addition, prolonged periods of starvation appear to have
no demonstrable benefit to ‘product quality’. Compassion in World
Farming (CIWF) believes that starvation periods of longer than
72 hours should be prohibited.
Some widely used slaughter methods for farmed
fish cause appalling suffering. So much so that the perpetrators
would be prosecuted if they were slaughtering other farm animals
in a similar way.
CIWF 2002
Percussive stunning by blow to the head – carried out
manually using a hand-held club called a "priest" for stunning,
followed by cutting of the gill arches to bleed the fish. Care
is needed to ensure that worker fatigue does not lead to inaccurate
or ineffective stunning.
Carbon dioxide stunning – fish are placed in a seawater
bath saturated with carbon dioxide (CO2). This environment is
highly aversive with fish being observed to shake their heads
and tails vigorously trying to escape (Robb et al. 2000). Movement
ceases after 30 seconds, but sensibility may not be lost for 4-5
minutes (Robb et al. 1997). Bleeding after CO2 stunning is essential
to avoid fish recovering. If fish are removed early from the stunning
tank, they are likely to have their gills cut when immobile but
still conscious.
Bleeding without prior stunning – gill arches are cut
with a knife and fish bleed to death. After gill cutting, the
fully conscious fish react vigorously, and cease moving after
4-7 minutes (Wall 1999; Robb et al. 2000). The FAWC (1996) states
that it is reasonable to assume that early convulsive movements
and muscular spasms are reactions resulting from pain or distress
caused by the method and conscious attempts by the fish to escape
the environment of the bleed-out tank.
Electrocution – electric current is passed through the
water containing the fish. The electric current must be sufficient
to stun and kill the fish, otherwise the fish are only paralysed
and could suffer considerably. This method can also cause spinal
fractures and haemorrhaging.
Asphyxiation in air or on ice – widely used in the trout
industry. Fish are hauled out of water and allowed to die through
suffocation in air, a method which the FAWC (1996) states as unacceptable.
Alternatively, they are removed from water into bins containing
ice, which prolongs suffering, as the cooling effect of the ice
can lengthen the time to unconsciousness. Kestin et al. 1991 show
that fish ‘harvested’ this way can still feel what is happening
to them 15 minutes after being taken out of water. FAWC (1996)
recommends that this method should be prohibited.
Source: CIWF 2002
Fish and pain
Teleost [bony] fish are considered to have marked
differences in some aspects of brain structure and organization
as compared to tetrapods [i.e. amphibians, reptiles, birds, mammals],
yet they simultaneously demonstrate functional similarities and
a level of cognitive development suggestive of sentience. Anatomical,
pharmacological and behavioural data suggest that affective states
of pain, fear and stress are likely to be experienced by fish
in similar ways as in tetrapods. This implies that fish have the
capacity to suffer, and that welfare consideration for farmed
fish should take these states into account. We suggest that the
concept of animal welfare can be applied legitimately to fish.
It is therefore appropriate to recognize and study the welfare
of farmed fish.
Chandroo et al. 2004
While fish cannot always express pain and suffering in ways
that humans can easily recognise, biologists and veterinary scientists
tell us that fish are capable of feeling pain. Chandroo et al.
(2004) conclude that fish are capable of suffering pain, fear
and stress in much the same way as four-legged animals, including
livestock, pets and hunted species, whose welfare is protected
under legislation.
The behaviour of captured fish should be evidence enough of
their suffering: their heart rate and breathing rate increases,
adrenaline is released, they gasp, struggle, and writhe, endeavouring
to escape and, by so doing, also demonstrate they have a will
to survive. Scientific studies substantiate these basic realities
and, thereby, underscore that suffering is inherent in the catching
and killing of fish.
[I]t has been shown that fish (like other vertebrate
animals, including humans) have a highly developed system that
may help protect them from severe pain — pain which could
endanger their lives if they were seriously handicapped by it
following some injury to their bodies, such as might be inflicted
by a large predator. This system releases natural opiate-like
substances (enkephalins and endorphins) once an animal is injured...
The presence of this pain-dampening opiate system implies that
there must be some capacity to experience pain, otherwise there
would be little point in animals having evolved such a system
in the first place.
Fox 1987
In a key 1996 report examining the welfare of farmed fish, the
Farm Animal
Welfare Council, the official independent advisory body to
the UK Department for Environment, Food and Rural Affairs (DEFRA),
noted the following:
"Almost all fish live the whole of their lives in water
and show a maximal emergency response when removed from water,
even for a very short period. This response includes changes
in heart rate, increased production of adrenaline, noradrenaline
and cortisol and vigorous muscle contractions..." These
changes "often indicate fear in the fish... All of the
scientific evidence concerning such effects makes it clear that
the term stress is certainly relevant to fish and that the means
by which stress effects are mediated are very similar to those
in mammals. Evidence that the term pain is applicable to fish
comes from anatomical, physiological and behavioural studies
whose results are very similar to those of studies on birds
and mammals. The fact that fish are cold blooded does not prevent
them from having a pain system and, indeed, such a system is
valuable in preserving life and maximising the biological fitness
of individuals. The receptor cells, neuronal pathways and specialised
transmitter substances in the pain system are very similar in
fish to those in mammals" (FAWC 1996).
The overcoming of the fishing industry and sport-angling led
"scientific" objection to fish feeling pain is best
summed up by Dr John Webster, Professor of Animal Husbandry at
the University of Bristol:
"A powerful portfolio of physiological and behavioural
evidence now exists to support the case that fish feel pain
and that this feeling matters. In the face of such evidence,
any argument to the contrary based on the claim that fish 'do
not have the right sort of brain' can no longer be called scientific.
It is just obstinate" (Webster 2005).
Regulation of farmed fish
welfare
EU level
In 2005 the European Commission published a proposal, COM(2005)297,
for a Council decision on the EU position concerning farmed fish
and the European
Convention for the Protection of Animals Kept for Farming Purposes
(pdf 15k). This arose from a recommendation concerning farmed
fish by the Standing Committee established under the convention.
Although not legally binding, the principles underpinning the
recommendation still inform future EU legislation in this area.
The starting point of the recommendation is that fish "shall be
farmed without detrimental effects on their welfare". Therefore,
inter alia, fish should be handled by trained staff and enclosures
containing fish should be inspected at least once a day. The recommendation
was adopted at the Council of Europe on 5 December 2005 and came
into force on 5 June 2006. Further work on detailed technical
appendices is ongoing.
Existing regulations in Ireland
European
Communities (Protection of Animals Kept for Farming Purposes)
Regulations 2000 (S.I. No. 127 of 2000) give effect to Council
Directive 98/58/EC concerning the protection of animals kept for
farming purposes. The main provisions are:
- Defines "animal" as any animal (including fish,
reptiles or amphibians) bred or kept for the production of food,
wool, skin, fur or for other farming purposes.
- Owner or keeper shall ensure the welfare of the animals under
his/her care and ensure that the animals are not caused unnecessary
pain, suffering or injury.
- Empowers an authorised officer to issue notices directing
the owner or person in charge to care for the animals in a specified
way including destruction of animals where there is a serious
risk to the welfare of the animals.
- Powers to seize, detain and destroy animals are included.
- Schedules lay down detailed requirements in regard to staffing,
inspection, record keeping, freedom of movement, accommodation,
equipment, feed and water etc.
Does Ireland give a damn?
In Ireland, the lead department regarding the recommendation concerning
farmed fish is the Department of Communications, Marine and Natural
Resources (DCMNR), whilst the Department of Agriculture and Food
also has an interest [1].
18. Dr Upton asked the Minister for Communications,
Marine and Natural Resources the actions his Department made to
prepare for the entry into force of the recommendation concerning
farmed fish of the Council of Europe's Standing Committee on the
European Convention for the Protection of Animals Kept for Farming
Purposes; the action he is taking now that said recommendation
has entered into force to ensure that Ireland's regulatory and
enforcement environment is such that it is entirely consistent
with the content of the recommendation; if he has identified the
shortfalls in said environment vis-a-vis its consistency with
the recommendation; and if so, the steps she will be taking to
ensure the recommendation is honoured. [23150/06]
Minister of State at the Department of Communications, Marine
and Natural Resources (Mr. Browne): The Recommendation concerning
farmed fish adopted by the Standing Committee of the European
Convention for the protection of animals kept for farming purposes
was adopted at the Council of Europe on 5 December 2005 and came
into force on 5 June 2006. The Recommendation is general in nature
and is due to be completed by detailed, technical appendices.
We have not yet received notification of when these appendices
will be produced, however, their consideration would include consultation
with the aquaculture industry here to establish what implications
there might be for fish farming practices.
It may be noted that European Community is a contracting party
to the Convention for the protection of animals kept for farming
purposes, and therefore it was the Community that voted in favour
of the Convention on behalf of EU Member States. Concurrent with
this Recommendation, a new EU Directive updating requirements
for fish health has been brought forward and is now close to adoption.
This Directive will be required to be implemented in accordance
with Regulation (EC) 882 of 2004 on official controls performed
to ensure the verification of compliance with feed and food law,
animal health and animal welfare rules.
In addition, the Department, in conjunction with the Marine Institute,
has been involved in facilitating an initiative led by the Irish
aquaculture industry to develop a Code of Best Practice for
the farming of finfish [i.e. ECOPACT], highlighting the
international standards to be adhered to with regard to the welfare
of farmed fish.
Parliamentary Debates 15-06-2006 (our emphasis in italic)
Clearly, the Irish government is dragging its heels in relation
to developing and implementing regulations concerning the welfare
of farmed fish, preferring instead to wait for the EU to first
implement a Directive requiring it to legislate. Meanwhile, the
DCMNR falls back on the usual "industry Code of Practice"
excuse.
Further emphasising Ireland's lack of commitment to the welfare
of farmed fish: As of 26 August 2006, Ireland was not among
the 12 signatories plus 2 countries intending to sign-up to the
European Cooperation in the field of Scientific and Technical
Research (COST) Action
867 "Welfare of fish in European aquaculture" memorandum of
understanding.
ECOPACT
A key objective of the voluntary Environmental
Code of Practice for Irish Aquaculture Companies and Traders (ECOPACT)
(pdf) is to "ensure health and welfare of livestock and a
healthy environment". Unfortunately, the Code doesn't give
practical guidance to the industry on how to improve and/or maintain
welfare standards, for example, regarding slaughter. Nor is it
an acceptable substitute for properly monitored and enforced regulations.
The ECOPACT document includes a copy of the Code of Conduct for
European Aquaculture, prepared by the Federation
of European Aquaculture Producers (FEAP). This Code addresses
the responsibility of the fish farmer to the fish, the environment
and the consumer. It recommends, inter alia, that the industry
"shall respect the considerations for welfare that apply
to the species being raised" and calls on aquaculturalists
to "ensure that every step is taken to safeguard the health
and welfare of such fish", including with regard to slaughter:
1. All fish should be fasted sufficiently before slaughter
so as to induce a completely empty digestive system.
2. Fish should be killed quickly and humanely, referring to
national regulations for guidance.
UK regulation
In the UK, the welfare of all farmed animals is protected by the
Agriculture (Miscellaneous Provisions) Act 1968 which makes it
an offence to cause or allow unnecessary pain or distress to livestock
on agricultural land. The Welfare of Farmed Animals (England)
Regulations 2000 set minimum standards for all farm animals. Owners
and keepers of animals are required to take all reasonable steps
to ensure the welfare of animals under their care and ensure that
the animals are not caused any unnecessary pain, suffering and
injury.
Regarding farmed fish, in addition to the general requirements
of the Welfare of Farmed Animals (England) Regulations 2000, the
Department for Environment, Food and Rural Affairs (DEFRA) are
working towards further improvements through other routes, including:
"The recommendations…[for farmed fish arising from
the Convention on the Protection of Animals Kept for Farming
Purposes] will provide an opportunity to create a code of recommendations
and work towards improvements throughout the EU. Our research
and development programme includes projects on certain aspects
of fish welfare. We will use the findings to support our objective
to ensure high standards of animal health and welfare"
(DEFRA 2006).
Farmed fish and welfare:
EU report executive summary
Societal and political background
Traditionally, the welfare of fish compared to welfare of other,
land farmed animals has not been an important topic to consumers,
producers and legislators, an attitude which is reflected in past
research projects and legislation directed towards welfare, which
hardly ever took fish into consideration. So why was and is fish,
compared to other animals, not a hot topic regarding welfare concerns?
First, there is a lack of tradition in perceiving fish as sentient
beings as fish do not evoke compassion and concern in humans in
the same way other, warm-blooded animals do; second, there is
still no consensus among scientists wether fish are able to perceive
pain and to suffer; third, large scale, industrialised aquaculture
is a relatively recent farming method.
Nevertheless, an increased concern for the welfare of fish in
general and especially in aquaculture can be noticed in recent
year, stimulated by research results suggesting awareness of pain
and suffering, and reports on farming conditions detrimental to
health and welfare.
A Norwegian study done by the National Institute for Consumer
Research in 2002 reveal that only 49% of the consumers considered
welfare of aquacultured fish to be acceptable. About 40% pinpointed
that they avoided buying certain fish types because they are sceptical
regarding what the flesh might contain of medicines and feed additives.
Welfare – general introduction
Traditional definitions of welfare often have either a feeling-,
nature- or functionbased approach or seek to combine those. Agreement
on how to correctly and best define welfare has shown to be difficult.
This difficulty has its origin in a disagreement regarding which
the essential and most important parameters for good welfare are.
The function-based approach analyses the animals coping with the
environment, or, as Broom quotes, "the welfare of an animal
is its state as regards its attempts to cope with its environment".
This definition is based on the assumption that the animal tries
to maintain homeostasis, equilibrium, in its physiological system.
The function-based definition assumes that a healthy body is an
indicator for good mental health, and important welfare indicators
are physiological parameters like stresshormones, health situation,
reproduction and growth.
The feeling-based approach has the subjective, mental state of
the animal in mind, and feelings like fear, pain and suffering
play a major role for good welfare. Physiological and behavioural
parameters are used when there is no possibility to assess the
emotional components directly.
The nature-based definition of good welfare requires that the
animal is given the possibility to perform normal and natural
behaviour. The animal is viewed in a holistic way, and this welfare
approach is important in for example ecological farming.
In order to secure welfare, the Brambell Committee Report postulated
in 1965 the "five freedoms":
1. Freedom from thirst, hunger and malnutrition by ready access
to fresh, clean water and adequate, nutritious food to maintain
full health and vigor. (applied to fish, this means that fish
should be provided with an adequate and nutritionally complete
diet according to the species and age specific demands. Food deprivation
before slaughter and transport should be a short as possible and
adapted to the species and age)
2. Freedom from discomfort by providing an environment suitable
to their species, including adequate shelter and a comfortable
resting area. (applied for fish this means species adequate water
quality parameters, flow rates and temperatures, appropriate light
intensities and other needs)
3. Freedom from pain, injury and disease by prevention, rapid
diagnosis and treatment. (applied to fish this means to prevent
injuries through careful and gentle procedures, prevent infections
and diseases through good sanitary conditions and eventually vaccination,
avoid malformations)
4. Freedom to express normal behaviour by the providing sufficient
space, proper facilities and company of the animal's own kind.
5. Freedom from fear and distress by ensuring living conditions
which avoid mental suffering (applied to fish this means ensuring
gentle and adequate handling procedures, stunning procedures before
slaughter which render immediate insensitivity to the animals,
human slaughter methods)
The five freedoms, originally postulated for land farmed animals,
can and should be applied to aquaculture fish.
Pain and discomfort in fish
The question of pain awareness is of huge significance for the
public concern about animal welfare. There is still no scientific
agreement regarding the question whether fish are, or not, capable
of perceiving pain.
Pain in humans is defined by the International Association for
the Study of Pain (1979) as "an unpleasant sensory and emotional
experience associated with actual or potential tissue damage,
or described in terms of such damage", and further "activity
induced in the nociceptor and nociceptive pathways by a noxious
stimulus is not pain, which is always a psychological state".
Several researchers state that fish are unable to feel pain in
a similar way to pain experienced by humans, arguing that there
is no awareness of pain without consciousness, and the capacity
of consciousness depends on functions of the neocortex. The neocortex
is absent in fish.
Because of the difficulty in assessing emotions in animals, emotions
and consciousness do not feature in the definition of pain in
animals and the assessment of pain is strongly attached to behavioural
and physiological parameters.
After reviewing the central and peripheral nervous system, neurotransmitters,
as well as physiological and behavioural responses of fish, several
new publications do conclude that it is highly probable that fish
have the necessary requirements in order to perceive pain and
to suffer. This position is also adopted by the European Food
Safety Authority, which in its scientific report regarding stunning
and slaughtering (2004) points out that there is enough evidence
indicating that fish is capable of feeling pain and suffering,
and this should be taken into consideration when talking about
fish welfare.
Welfare indicators
The choice of indicators is dependant on the level and type of
information required.
Physiological indicators
Many husbandry activities in aquaculture, like handling of fish,
transport and vaccination, lead to stress responses in the organism
which, if chronic or intense, eventually can lead to welfare impairment.
Stress responses can be divided into primary, secondary and tertiary
responses. Primary responses to stressors are the release
of catecholamines and corticosteroids. Secondary responses
are characterised as the immediate reactions of blood and tissues
to those hormones. Finally, the tertiary responses are
determined as being long term responses influencing growth, reproduction
and immune responses.
Hormone and glucose level in the blood can be measured and used
as indicators for the animal´s stresslevel.
Behavioural indicators
Impaired welfare as well as good welfare and environmental changes
reflect in the behaviour of fish and can among others cause visible
changes in colour, breathing frequency, social and swimming behaviour
and feeding. Behavioural measures are therefore sensitive indicators
of the biochemical and physiological changes occurring in response
to stress. As altered behaviour is an easily observed response,
giving immediate information without the need to use invasive
methods, specific behavioural responses can be used as indicators
for stressful and/or welfare-threatening situations.
Other indicators
Further indicators for welfare are general condition of the fish
(scale loss, damaged fins, etc), growth, reproduction, and health.
Welfare issues
There are several aquaculture conditions which may have an influence
on animal welfare, including:
Fish densities in farming
Increasing stocking densities compared to the natural densities
of fish species means that the number and the type of fish interactions
increase. The naturally evolved behaviours are adaptive and reflect
the most adequate way to react in order to cope with the environment
in an efficient way, which implies that increased stocking densities
normally affect this balance. The biology of the cultivated fish
species is complex, to identify adequate stocking densities is
therefore difficult and must take age, size, environmental conditions
and biological characteristics of the species into consideration.
Environmental parameters
Fish are in constant interaction with their environment through
the surface of the gills and the skin, therefore water quality
(oxygen, ammonia, pH) and the level of present contaminants are
crucial for welfare. Water quality should be constantly and carefully
monitored and reflect the needs of each species and developmental
stage.
Malnutrition
It is important to notice, that feed formulations can have both
negative and positive effects on health and welfare; diseases
originated from missing micronutrients being an example for a
negative effect, the improvement of the immune system through
the oral administration of glucan a positive one.
Most feed formulations contain high proportions of marine fish
meal and oil in order to match the fatty acid and amino acid needs
of the cultured fish. The main reasons are the high demand for
protein, and secondly the high demand of polyunsaturated (PUFA)
fatty acids. Inadequate levels of fatty acids have a negative
impact on the immune function and can lead to a decrease in antibody
production.
The major challenges regarding the vegetable alternatives are
the different content and composition of FA and AA, and the presence
of so-called anti-nutrients. Antinutrients represent a welfare
problem in themselves, as they can lead not only to reduced absorption
and digestion, but also to diseases in the intestinal systeme.
In addition, the oil content of the vegetable alternatives is
lower and the carbohydrate content poorly utilised by fish.
Food deprivation
Food deprivation is used in order to adapt production to the market
demand, before transport to reduce metabolic rate and oxygen consumption
and production of waste products, and before slaughter aiming
to eliminate gut contents and reduce contamination risks.
Important to notice is here that the natural behaviour of reduced
feeding is temperature-, age-, species and season dependent, implicating
that depriving fish from food during non-natural periods might
lead to reduced welfare.
Cataracts
The incidence of cataract ("grey star") in intensive
culture of Atlantic salmon has increased significantly, and also
sea bass and sea bream have been shown to be affected by cataract.
Behavioural changes and reduced growth due to difficulties in
feeding are direct consequences of cataract.
Several factors are known to be related to cataract formation.
Among these are environmental conditions (ex.: temperature), nutrition
(ex.: deficiency in histidin, methionin, zinc), toxins, genetic
predisposition and parasites.
Deformities (skeletal and tissue deformities)
Skeletal deformities represent not only an ethical and welfare
issue but have a negative impact on economy and quality as well,
due to growth impairment in the affected fish, elevated mortality,
reduced fillet quality and smolt which cannot be sold. Skeletal
deformities include spinal cord, head, mouth and opercular deformations,
and affect most of the farmed species.
Factors responsible for the induction of malformations are genetic
disposition, malnutrition (especially during fast-growth periods)
and environmental parameters (temperature, oxygen content etc.).
During the last years, an increasing number of apparently healthy,
large fish showed problems in coping with normal aquaculture procedures
like transport, handling and grading due to tissue deformities
like abnormally shaped hearts. A combination of sedentary lifestyle
and breeding programs that do not take organ functioning into
account could be the origin for the increasing amount of anomalies.
Vaccination – side effects
Vaccination programs have contributed significantly to reduce
the losses due to disease outbreaks in fish farming, and represent
in addition the major factor for the enormous reduction in antibiotic
used in aquaculture. Vaccination, and especially intraperitonial
vaccination with oil adjuvant vaccines, may be hampered by severe
side-effects. Beside the loss of appetite, more severe side effects
of oil-adjuvant vaccines are tissue adhesions of variable degree
around the injection site, pigmentation and granulomata. Severe
lesions can disturb and interfere with the normal function of
the affected organs, resulting in reduced growth and impairing
animal welfare.
Transport
Farming fish often includes transport of living fish, normally
at high densities, with loading, capture, netting and pumping
procedures involved. During transport inadequate water exchange
depleting the oxygen content and accumulating carbon dioxid and
ammonia may further contribute to stress reactions and impaired
welfare.
Stunning/sedation
From an animal welfare point of view any method of slaughter should
incorporate a stunning procedure that renders the animal immediately
insensitive and unconscious until death. Many of the currently
used slaughter methods are inadequate from a welfare perspective.
Table
1 pop-up. Stunning (stun) and killing (kill) methods that are
used for slaughter in the most common European farmed fish species.
Not determined (n.d.) and not appropriated (n.a.) methods indicated
as well (after Roth 2003).
Wolffrom 2005
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