ISA models lack real-world validation; distance alone won't stop virus spread

For two decades, the salmon farming industry has relied on mathematical models to anticipate how infectious salmon anaemia moves between farms—yet a systematic review now reveals that most of these models have never been tested against real outbreaks. Distance between farms does reduce risk in measurable ways, but shared vessels, workers, and equipment can quietly undo that protection, and more than a third of documented transmission cases remain unexplained. The gap between elegant theory and messy reality is not merely academic; ISA can destroy over 90 percent of fish at a site, and the 2007