Monitoring fish welfare in commercial aquaculture requires practical tools that can be applied at scale, by farm staff with varying levels of training. Operational welfare indicators (OWIs) — observable signs of fish wellbeing — are increasingly integrated into farm management systems and regulatory frameworks.
OWIs provide a standardised framework for ongoing welfare monitoring. For salmonids, key OWIs include:
Camera-based systems with computer vision analysis are increasingly available for continuous fish welfare monitoring. Systems can track swimming speed and pattern, feeding behaviour, and detect surface-breaking behaviour in real time, providing continuous welfare data streams. These technologies complement but do not replace direct observation by trained staff.
SWIM is a validated welfare assessment protocol for farmed Atlantic salmon, incorporating multiple OWIs into a standardised composite score. Developed by Aquaculture Health Ireland and now used internationally, SWIM provides a benchmarking framework for comparing welfare outcomes across farms and over time.
Fish welfare monitoring data is most useful when integrated with other farm management data — water quality, feeding records, mortality records, treatment histories — to identify patterns and correlations that enable proactive management. Welfare monitoring should drive management decisions rather than simply documenting problems.