Animal welfare in modern production systems for fish
FRESH - Fish REaring and Stress Hazards
A Formas funded interdisciplinary project aiming at improving fish welfare in commercial fish production systems.
(Photo: Rainbow trout in net pens.)
A joint project between the Department of Animal Environment and Health and the Department of Animal Nutrition and Management, both at the Swedish University of Agricultural Sciences (SLU) and the Department of Biological and Environmental Sciences, University of Gothenburg (GU).
- Invitation to dissertation - On Friday September 8th David Huyben, one of the PhD students in the FRESH project will defend his thesis. The title is "Effects of feeding yeasts on blood physiology and gut microbiota of rainbow trout", and the oral defence will take place at 9.15 at Ultuna, Uppsala (hall Audhumbla, VHC). Everybody welcome! More information here.
- We are looking for a new PhD student for a project on physiological assessments for improved welfare of farmed fish. Please see the full ad here!
- Dissertation - at the 10th of Februari 2017 our project member Jeroen Brijs defend his PhD thesis "Gastrointestinal motility and blood flow in teleosts during digestion and osmoregulation".
Researchers: Bo Algers (SLU), Michael Axelsson (GU), Lotta Berg (SLU, co-ordinator), Jeroen Brijs (GU, not in photo), Albin Gräns (GU), David Huyben (SLU, not in photo), Anders Kiessling (SLU), Torbjörn Lundh (SLU) Erik Sandblom (GU), Kristina Sundell (GU) and Henrik Sundh (GU) .
General aim of the project
- Establishing a world class fish welfare platform.
- Obtain physiological data enabling identification of cause and effect,
- Establish quantitative comparison of critical situations for farmed fish,
- Develop specific recommendations and basis for legislation to ensure animal welfare and improve future production and management systems.
What are the problems in fish welfare research?
- Fish lack discernible facial expression and most farmed species also lack vocal abilities.
- Fish in a production environment has a very limited behavioural repertoire and is hard to observe visually.
Hence, it is difficult for a human caretaker to perceive fish expressions of distress.
Possible stressors in commercial fish farming
Capture and handling procedures such as netting pumping, sorting, vaccination, treatment, transport, nutritional disorders as well as aggression and inability to hide from threat and infections. Several of these stressors will be evaluated within the project.
Physiological stress indicators for fish in general After perceiving stress, a primary stress response, i.e. increased circulating levels of catecholamines (CAT) and cortisol, is initiated through the hypothalamic-pituitary-interrenal axis. This elicits secondary stress responses, in fish documented as cellular, osmoregulatory, hematological, barrier or immunological changes. This may create tertiary stress responses, affecting performance and manifested as decreased growth, swimming capacity, disease resistance, feeding activity and altered behaviour.
Stress indicators currently used at fish farms
- Flight attempts in direct conjugation with the stressor,
- Reduced feed intake over days and even weeks after a stressful event,
- Reduced growth and increased mortality and/or increased diseases occurrence is a more long term and multi‐cause response.
Methods to be used in this project
To understand the causality and severity of different farming practises, physiological responses in vivo and in vitro will be studied in the fish at site.
- A telemetric dual-channel Doppler blood flow system, measures total cardiac output flow, gut blood flow, heart rate and body temperature.
- Using chamber techniques, evaluates the integrity of the intestinal primary barrier, a well-established secondary stress response and welfare indicator.
- Primary stress responses will be measured using non-invasive and invasive methods. Use of permanent cannula in in order to obtain repeated blood samples in normally feeding and behaving fish.
- Non-invasive techniques ensures representative baseline and stress values of the secondary stress responses, heart and respiration frequency, in non‐experimentally influenced fish.
- Controlled laboratory experiments on instrumented fish under mimicked farming situations will study the mechanisms of specific physiological responses.
Figur 1. Modern fish farming system in western Norway. Such an enclosure can have a circumference of up to 120 meters and house more than 100,000 animals. To study the individual animals in such systems is almost impossible today, but nevertheless crucial when aiming at ensuring not only the welfare of the fish but also at developing rational and well-functioning production systems. (Photo: Anders Kiessling)
Figure 2. Stress response systems in fish.
The project has 4 sub-projects, please see links below:
- Study 1: Why is the intestinal barrier in fish affected by stress?
- Study 2: How are fish affected by identified welfare problems in the lab and in aquaculture?
- Study 3: Effect of alternative feed resources on the fish normal intestinal micro flora and the intestinal barrier function.
- Study 4: The effects of turbid water in combination with high water temperatures on oxygen consumption, heart and ventilation rates.
Links to current knowledge:
Some EFSA reports on fish welfare
- General approach to fish welfare and to the concept of sentience in fish
- Knowledge gaps and research needs for the welfare of farmed fish
- Animal welfare aspects of husbandry systems for farmed Atlantic salmon - Scientific Opinion of the Panel on Animal Health and Welfare
- Species-specific welfare aspects of the main systems of stunning and killing of farmed Atlantic Salmon
Links to involved research departments:
- Department of Animal Environment and Health, SLU, Skara, Sweden
- Department of Biological and Environmental Sciences, University of Gothenburg, Sweden
- Department of Animal Nutrition and Management, SLU, Skara, Sweden
Links to relevant contacts:
- Fiskhälsan FH AB (in Swedish)
- Statens Veterinärmedicinska Anstalt (SVA), Sektionen för fisk (in Swedish)
- Jordbruksverkets information om vad som gäller för odling av vattenlevande djur (in Swedish)
Link to main funding organisation: