Moving beyond disease and mortality metrics, positive welfare indicators for farmed salmon assess thriving behaviour, normal activity, and signs of good affective states in fish.
The welfare science of farmed salmon is advancing beyond simply preventing bad outcomes toward understanding what good welfare looks like for fish. Positive welfare for salmon means more than absence of disease — it means fish swimming actively at appropriate depths, feeding eagerly, schooling cohesively, and engaging with their environment in ways consistent with positive affective states. Developing practical positive welfare indicators for salmon is challenging because fish do not show welfare through body language as clearly as mammals, and because commercial-scale assessment requires tools that work at population level rather than requiring individual assessment of thousands of fish. Acoustic monitoring, underwater camera analysis, and aggregate behavioural metrics offer promising approaches. The direction of travel in aquaculture welfare science is clear: as the field matures, the standard of care will increasingly be expected to demonstrate positive welfare alongside the traditional negative welfare metrics of mortality and disease rates.