Stress and welfare in teleost fish
Dr. Neil Ruane
Marine Institute
Awareness of Fish Welfare
Awareness of Fish Welfare
Directive 98/58/EC – protection of animals kept for farming purposes.
EC. 2002. A strategy for the sustainable development of European
aquaculture. Commission of the European Communities COM (2002)
511 final, 26 pp.
“promotion of animal health and welfare as one of the three main
objectives for the sustainable development of European aquaculture”
ec.europa.eu/food/animal/welfare/index_en.htm
Council of Europe – European Convention on the protection of animals
kept for farming purposes: Recommendations for farmed fish (06/2006)
www.coe.int
In 2008 the World Organisation for Animal Health (OIE) adopted
guiding principles for fish welfare
www.oie.int
Awareness of Fish Welfare
European Food Safety Authority – Animal Health & Welfare Panel: risk
assessment of the welfare of 6 species (salmon, trout, sea bream, sea
bass, eel, carp) – basis for future legislation?
www.efsa.europa.eu
In 2009 the AHAW panel adopted an opinion on the general approach
to fish welfare and produced documents on stunning and killing
methods for 7 species (tuna, carp, salmon, trout, sea bream, sea bass,
eel and turbot).
Concept of fish welfare
• Who cares?
- Producers: responsibility; image; CoP’s; profitability
- Processors: flesh quality; reputation
- Scientists: research opportunity; funding; obligation
- Welfarists: genuine concern (RSPCA; Freedom Foods); PR
- Consumers/Retailers: consumer perception; education; sales
• Animal welfare refers to the quality of life or well-being
• applied to sentient beings (self awareness, experience pain,
suffering)
• controversial area in fish biology
• duty of care to the animals
Awareness in fish
Watching other fish
fighting increased
androgen levels in
spectator fish
Androgens – sex
hormones; social status;
agressiveness
Concious or reflex?
Dangers of
anthropomorphic
explanations
Whether fish are sentient or not, the exposure of
fish to stressors/poor conditions should be
avoided or kept to a minimum
On-farm Stressors
Water Characteristics
Chemical components
Temperature
Salinity
O2
Hardness
pH
Culture procedures
Handling
Confinement
Stocking density
Air exposure
Vaccination
Culture system
Behavioural Interactions
Interspecific competition
Social dominance
Territoriality
Welfare indicator: 1o stress response
Hypothalamus
Sympathetic
nerves
CRH
Pituitary
ACTH
Head kidney
Chromaffin cells
Interrenal cells
Catecholamines
Cortisol
MANY SITES OF ACTION
Interrenal cells in carp head-kidney
Welfare indicator: 2o & 3o responses
Secondary responses:
- energy mobilisation (increased glucose, fatty acids)
- changes in the immune system (reduction in circulating
lymphocytes)
- ion (Na+, Cl-) levels change in the blood
Tertiary responses:
- reduced growth/poor appetite
- immune suppression/disease outbreak
- impaired reproduction
23
21
19
17
15
13
11
9
7
5
Sep Oct Nov. Dec Jan Feb Mar Apr May
Mortality
Feeding
Temp
warm
140
% respect to warm period
(Sparus auratus)
9
8
7
6
5
4
3
2
1
0
cold1
Temperature 0C & Cortisol ng/ml
Winter disease - Gilthead seabream
% feeding & % mortality
Link between stress and disease
Cortisol
cold 2
120
100
80
**
* *
**
*
* *
60
40
20
0
agglutination ach50
lysozyme lymphocytes
NBT
Tort et al., 1998. Comparative Biochemistry & Physiology A 120: 175-179
Link between stress and disease
Fig. 2. Cumulative mortality of the cohabitees (Atlantic salmon) after IPNV challenge from day 0 to 47 post-challenge, shown as
mean±SE. Description: ▴: non-challenged fish and represents both the normoxic and hyperoxic group, ●: Challenged,
hyperoxygenated group, ■: Challenged, normoxic group. Ndead=110.
Fridell et al., 2007. Aquaculture 270: 23-35
Link between stress and growth
Daily exposure to stress
reduces growth in juvenile
carp
Ruane et al., 2007. General Comparative Endocrinology 150: 473-479
Stress/welfare on the farm - transport
Many disease outbreaks occur during the first months of transfer to sea
- stress of transportation
- prolonged stress leads to immunosuppression
- smolts are more sensitive to stress compared with parr
Carey & McCormick, 1998. Aquaculture 168: 237-253
Commercial well boat transport of Atlantic salmon
- loading more stressful than unloading
- stressful transport linked with high mortalities
- well boats can play a role in recovery of the fish
Iversen et al., 2005. Aquaculture 243: 373-382
Stress/welfare on the farm - noise
Effects of environmental noise initially focussed on sonar, pile driving,
seismic air guns Now looking at aquaculture – chronic exposure to noise
Fish have highly developed sensory systems
- hearing: combination of the lateral line and ear
Hearing specialists – cyprinids (still water more quiet)
Hearing generalists – salmonids (fast flowing rivers more noise)
Stress/welfare on the farm - noise
Effects of noise:
-Induces a stress response in
exposed fish
- Can induce temporary hearing
loss
- Specialists more sensitive
- Fish can recover over time
Smith et al., 2004. Journal of Experimental Biology 207: 427-435
Monitoring Welfare/Stress on farms - OWI
• Many methods of monitoring stress are a stressor in themselves
• There is a need for non-invasive welfare/stress monitoring
- Operational Welfare Indicators (OWI)
- observe behaviour, remote sampling
- measurement of cortisol, or other stress-activated compounds, in
urine, faeces or water
Ruane & Komen, 2003. Aquaculture 218:685-693.
Monitoring Welfare/Stress on farms - OWI
Operational Welfare Indicators – factors which can be corrected
Direct OWI’s – relate to the fish
Indirect OWI’s – relate to the system
Practical OWI’s:
• Farm conditions
• Water quality
• Behaviour/appearance
• Nutrition/feeding
• Health
• Serology/physiology
EU projects on fish welfare
AQUAFIRST – selective breeding to improve disease and stress resistance in fish
and shellfish
http://aquafirst.vitamib.com
FASTFISH – on farm assessment of stress levels in fish
http://fastfish.imr.no
FINE FISH – reduction of malformations of juvenile fish in hatcheries
http://www.finefish.info
COST 867 – a network on fish welfare in European aquaculture
http://www.fishwelfare.com
BENEFISH – benefits and costs of fish welfare in European aquaculture
http://www.benefish.eu