Tackling the elephant in the room - Large-scale salmon farming and the potential for far-field ecosystem effects.

Significant expansion in salmon production globally has been partially enabled through the establishment of large-capacity sea-farms in high-energy environments that collectively produce substantial quantities of organic waste with potential to cause regional scale environmental degradation. We analyse results from comprehensive spatial and temporal surveys of water column particulates and seabed environmental indicators for responses to farm production, and residual effects. Results confirmed that while the particles can and do reach a relatively wide area, benthic effects do not necessarily follow suit. There was limited evidence of longer-term environmental degradation at some near-field locations and spatially removed deeper sites. We concluded that evidence for regional biological effects was negligible, suggesting: i) modern waste tracing techniques are more sensitive than traditional effects indicators, and ii) waste fluxes in the far-field were being assimilated without causing environmental perturbation. Monitoring at potential accumulation points, especially for sites with complex bathymetry and hydrodynamics is advised.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Nigel Keeley reports financial support was provided by Norges Forskiningsrad. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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