Life cycle assessment of gilthead seabream (Sparus aurata) production in offshore fish farms

Life cycle assessment is used in this study to evaluate the potential environmental impacts of producing gilthead seabream in an offshore sea farm exposed to storms in the Spanish Mediterranean Sea. The farming methods used can be considered as "basic" since no centralized or automatic food distribution system exists and there is no control system. This study aims to identify the main hotspots under these conditions and to propose and compare viable alternatives to them. Contribution analysis found that the component of the system with the greatest potential environmental impact (48% of the overall impact) was fish feed, especially the raw material used. Other contributory factors were the fuel consumed by the vessels operating in the farm (35%), the dumping of N and P in the environment due to the metabolism of the fish (12%), the cages and their anchorage system (5%). A sensitivity analysis showed that a significant reduction in potential environmental impact can be achieved by increasing feeding efficiency. Feed formulation in raw materials is also an important factor and could serve to diminish overall adverse effects. A balance needs to be found between productive performance (growth, survival and feed conversion rate), feed price and its influence on production costs and the overall environmental consequences.