The Scottish government has now accepted that there is a risk to wild salmon & trout from sea lice hosted by fish in open net salmon farms. SEPA has been tasked with developing a new regulatory framework & is currently consulting on its models & approach. The CCN models developed to date illustrate the combined densities of sea lice from farms all along the West Coast but SEPA’s models are based on a local level approach & this needs to be mirrored in the CCN models to enable weaknesses to be challenged robustly. There is also a need to add a new work stream – collating information from the cumulative distribution of sea lice models & overlaying this with a ‘virtual fish tracking’ element to illustrate the likely cumulative risk to wild fish as they traverse the seas. SEPA models only consider cumulative risk within pre-defined zones & assume there is no risk outside these zones (in contrast to the CCN models which show more widespread risks). This grant will enable the CCN models (already supported by HIEF grants) to mirror the models currently under development by SEPA & the aquaculture industry & thus enable weaknesses in both models & proposed regulations to be challenged before they are set in stone.