Sea-based Integrated Multi-Trophic Aquaculture: Investigation of a fish, bivalve and macroalgal co-culture system.
Sea-based integrated multi-trophic aquaculture (sIMTA) was explored as an amalgam of the processes of polyculture and biofiltration, with the primary objectives of improved aquaculture production efficiency and wastes remediation. The study established a coculture of Atlantic salmon (Salmo salar, L.), Pacific oyster (Crassostrea gigas, Thunberg) and sugar kelp (Saccharina latissima, L.), in Scotland, and explored their production in relation to the background environment, historical aquaculture production modes, regulation and resource-use. The field trials demonstrated the dominance of the ambient environment in regulating trophic linkage of co-cultures. Enhanced growth of the bivalve and macroalgal components, over reference cultures, was only observable when ambient nutrients were limiting or favoured food, i.e. phytoplankton, was scarce. Localised differences within and between sealoch systems were also observed to be of importance. The complex physical processes of particulate waste dispersion and dissolved nutrient diffusion were simulated using established models and field data drivers. This process illustrated the potential benefits of designing the integrated farm to optimise trophic linkages as well as considering the final fate of wastes. The application of sIMTA was explored within the current regulatory regime, illustrating what regulatory gains (statutory and non-statutory) might be possible on account of the process and how the products of integration, as studied, are likely to meet with few regulatory food safety constraints within a UK market. The scarcity of aquaculture resources, partly through inefficient use, was explored. sIMTA is presented as a method which could possibly alleviate some of these resource-use inefficiencies when ambient environment supports, and as such sIMTA is proposed to qualify for priority resource allocations, in the context of greater socio-economic advantage.
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