Water quality and feeds more important than farming method in aquaculture

Scientists at Europe's food safety watchdog EFSA have addressed the impact of various farming systems on the welfare of Atlantic salmon.

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), a panel appointed by the watchdog said.

In its risk assessment, the Panel produced a ranking system for risk managers to gauge the welfare of the different methods. The opinion also provides recommendations for future scientific research.

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 (fishmeal alternatives) 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 fishmeal and oil is important to meet their nutritional requirements.

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.