Infectious Salmon Anaemia (ISA) is a devastating viral disease of farmed Atlantic salmon that causes mass mortality and welfare crises when outbreaks occur.
ISA outbreaks represent acute welfare crises of enormous scale. Fish dying from ISA experience a prolonged deterioration over days or weeks - organ failure, haemorrhage, and respiratory compromise as red blood cell destruction prevents oxygen transport. The mass culling operations that contain outbreaks involve crowding and gas exposure or suffocation of entire cage populations - an acutely stressful death for fish that might otherwise have survived. Prevention is overwhelmingly the welfare priority: biosecurity protocols that prevent ISA introduction eliminate the possibility of both the disease suffering and the culling welfare cost.