Validating Particle Tracking Models Of Sea Lice Dispersion In Scottish Sea Lochs

No abstracts are to be cited without prior reference to the author.

Lepeophtheirus salmonis is a naturally occurring parasite on wild salmonids. Infestations of this sea louse pose a major economic burden to the Atlantic salmon aquaculture industry and may be linked to the decline of wild salmonid populations. Coupled models of surface circulation and louse biology have been used to understand the dispersion of planktonic larval lice from a point source, such as a fish farm. We have developed a sea lice dispersion model for Loch Torridon, a fjordictype sea loch on the west coast of Scotland, using output from two different hydrodynamic models. Surface circulation within Loch Torridon shows significant deviation across-loch from expected estuarine transport due to the complex shoreline geometry and relatively low freshwater input. Validation of transport has been carried out with a combination of current meters and drifter studies, in order to ensure transport patterns within the loch are represented. Simulated dispersal patterns of viable sea lice demonstrate a high dependence on wind and freshwater forcing, such that validation must be carried out under a range of environmental conditions. Further, complex coastlines of Scottish fjords mean that wall parameterizations can have significant influence on individual particle tracks. As this cannot be validated using drifter studies, a numerical exploration of the impact of varying wall parameterizations is undertaken.