Environmental sustainability assessment of offshore mussel farming: An LCA approach

Shellfish aquaculture is typically located in sheltered nearshore environments, with offshore expansion offering potential to significantly increase production in less contested marine space. Life Cycle Assessment (LCA) analysis was conducted for blue mussel ( Mytilus edulis) farming in Lyme Bay, UK, evaluating the environmental sustainability of this emerging aquaculture system. The main hotspots of the farming process, across all impact categories, are fuel use to access the farming area and use of plastic materials, and their subsequent disposal, in construction of the long-line system. Global Warming Potential (GWP) of the farming process (0.29 kg CO 2 eq. kg −1 whole mussels) falls within the reported range for traditional mussel aquaculture, comparing very favourably to terrestrial meat production and fed aquaculture. GWP lowered (0.22 kg CO 2 eq. kg −1 whole mussels) accounting for a proportion (40%) of carbon in mussel shells as sequestered. GWP of shucked meat was 0.45 and 0.89 kg CO 2 eq. kg −1 for 50% and 25% meat yields, respectively. Eutrophication Potential was low (0.23 × 10 −3 Kg N eq. and 0.01 × 10 −3 kg P eq. kg −1 whole mussels), with net negative values (−9.71 × 10 −3 Kg N eq. kg −1 and − 0.29 × 10 −3 Kg P eq. kg −1 whole mussels) accounting for retention of nutrients in flesh and shell. Overall, the results demonstrate that offshore mussel farming is a highly sustainable food production system. As this form of aquaculture becomes more widespread, comparative LCA analysis could usefully be extended over a wider range of environmental and operational conditions.