Summary: This report demonstrates how the Scottish fish farming industry is failing to contain sea lice parasites on its open-net farms, with potentially severe consequences for wild Atlantic salmon and sea trout. In 2022, twothirds of Scottish marine fish farms breached the industry’s own Code of Good Practice (CoGP) sea lice thresholds on at least one occasion. The poor compliance comes despite the fact that the CoGP limits are in themselves five times more lenient than best global industry practice.