Aquaculture

The Scottish Shelf Model (SSM) is being used to guide the regulation and sustainable management of the aquaculture industry. A good example of this is recent work undertaken at Marine Scotland Science (MSS) and the Scottish Environment Protection Agency (SEPA) to help with the development of a regulatory framework to limit the potential damaging effects of sea lice from farmed salmon to wild salmon. The SSM flow fields were used to estimate the residence time of sea lice in 300 water bodies, including sea lochs, sounds and river mouths, deemed to be potential bottlenecks for the interaction of farmed and wild salmon. Previously residence time estimates for sea lochs were made using a small number of old calculations. The high resolution and large spatial coverage of the SSM was an essential element of this work.  MSS continue to validate, refine and develop the SSM framework to increase the robustness of this approach.

SEPA are primarily responsible for the regulation of several aspects of the aquaculture industry (e.g. discharges from finfish farms by issuing permits that limit the levels of material and pollutants that they discharge to the water environment).  SEPA routinely use small scale, local, hydrodynamic models to explore how waste products from both individual and multiple fish farms may affect the environment. SEPA are increasingly making use of the SSM model outputs, primarily the climatological outputs, to force their local models. The advantages of the climatological SSM outputs are that they do not represent any one, potentially unusual year.  Similarly, the aquaculture industry are using the SSM outputs to explore the general flow characteristics and potential connectivity of potential aquaculture sites and to help with decisions such as when to treat farmed fish for parasites or infections.  SEPA also use simplified versions of SSM model grids as part of their aquaculture applications pre-screening process.

Work carried out by MSS scientists (Ounsley et al., 2019) has provided new insights into how salmon smolts navigate Scottish coastal waters on their way to their feeding areas in the open seas.  This work can be expanded in combination with sea lice modelling (see above and biological connectivity section) to quantify their potential exposure to sea lice emanating from fish farms.