EFSA looks at the impact of husbandry systems on the welfare of Atlantic salmon
Scientists at Europe’s food safety watchdog have addressed the impact of various farming systems on the welfare of Atlantic salmon. Experts of EFSA’s AHAW Panel considered that the main factors affecting Atlantic salmon welfare are water quality, stocking density, diet and the process by which the fish are sorted by size (grading). In its risk assessment, the Panel produced a ranking system for potential welfare hazards in the various farming systems, which can be used by risk managers to gauge the welfare of the different methods. The opinion also provides recommendations for future scientific research.
“Experts found that, with respect to animal welfare risk, it is the interaction of key elements of the Atlantic salmon farming systems which play a determining role as opposed to any intrinsic differences in the farming methods themselves” commented Dr. Philippe Vannier, Chair of the AHAW Panel. “This opinion will be followed by other opinions on main fish species: rainbow trout, gilthead sea bream, sea bass, carp, and European eel. The opinion of the AHAW Panel also took into account the results of the discussions of a stakeholders’ meeting organised by EFSA", said Dr. Vannier.
The AHAW Panel identifies water quality as essential for fish welfare and recognised several damaging effects of poor water quality on fish health. The Panel concluded that the introduction of novel, non-marine feed can lead to some problems due to the lack of essential nutrients such as amino acids and polyunsaturated fatty acids, although there is evidence that it could potentially partly replace high quality fish meal. For Atlantic salmon, a diet containing a high proportion of marine fish meal and oil is important to meet their nutritional requirements.
Grading systems are an important element in husbandry and should be set up to minimise the time fish are out of the tanks or cages, to ensure sufficient water quality is maintained, and to limit stress. Stocking density was also considered to be relevant. However, it is impossible to establish maximum and minimum levels of stocking that would safeguard fish welfare due to the interaction of stocking density with many other factors.
Disease and disease control measures are also of great importance for salmon welfare. While vaccines have made a significant contribution in controlling serious infectious diseases, several risks were identified. The limited availability of veterinary medical products approved for Atlantic salmon constitutes an important risk, therefore the Panel recommends that future research on vaccines and vaccination methods is necessary.
Given the impact that different production systems can have on fish welfare, scientists recommend a constant monitoring of the environment, fish size, health and behaviour. They also recommend further research to be carried out in such areas as feeding, stocking density, and veterinary therapeutics and vaccines.
A member of the AHAW Panel expressed a minority opinion requesting that additional information related to fish welfare in general be included in the final opinion.