06 Wild-Farmed Interactions
There are many potential interactions between aquaculture activities and the environment in which it operates. However the most important farm-wild interactions with respect to the long term sustainability of the salmon aquaculture sector are sea lice and escapes.
The potential exists for sea lice emanating from fish farm cages to impact on wild salmonids and vice versa. However, detailed scientific evidence to assess and quantify the extent of any impact in Scotland is limited and it is important that key knowledge gaps are filled through experimental and other studies.
Introduction of non-native salmon into the environment may occur through accidental escapes from aquaculture facilities or historically through deliberate introductions of stocked fish. Several studies outwith Scotland over the last decade report that when hybridization between indigenous and non-indigenous fish occurs a fitness cost may be incurred to wild populations, causing increasing awareness and concern about both conserving native fish gene pools and to the continuing health and viability of the wild populations. However, in Scotland there has been a general decline in reported escapes, which is partly due to activities of initiatives such as the Improved Containment Working Group including moves towards a Scottish Technical Standard for Containment.
There is also a lack of information on the potential for transfer of disease between farmed and wild fish. Wild fish are the ultimate source from which pathogens emerge in farmed fish and he exact role of farmed and wild fish in pathogen outbreaks will be determined by their respective densities in a given area.