THE PROBLEM TO SOLVE

At the European level, the aquaculture sector, and in particular mariculture, is growing strongly and more than 50% of the products of aquatic origin consumed by the world population are estimated to derive from aquaculture. According to the World Bank’s forecast scenarios based on projections of consumption data and population growth, a request for 261 million tons of aquatic products is expected in 2030, of which over 62% will have to be secured with aquaculture products. To meet the demand, aquaculture will have to triple its production.

Although environmental impacts tend to be lower than fisheries with less exploitation of natural fish stocks, they are not negligible.

The water and waste of mariculture plants are a problem for the surrounding ecosystem as they cannot be treated and recycled as well as those on the ground being located in cages at sea. In most fish farming systems, metabolic by-products, food residues, faecal material and residues of prophylactic and therapeutic compounds are discharged directly into the sea, without treatment, thus leading to deterioration of water quality and the appearance of diseases in bred species as well as possible infections in humans. The greatest risks derive in particular from the release of xenobiotics but also from nitrogen and phosphorus that cause problems of eutrophication and pathogens like bacteria, viruses and protozoa. The consequences of organic enrichment are evident not only in the water column but also in the sediments that in normal condition can host a great biodiversity.

These negative environmental impacts are particularly evident in plants located near the coast, in confined area where the diluting effect of the marine circulations is less effective.

The expected development of the aquaculture sector, in the coming years, in Europe, will therefore have to provide for the development of systems to mitigate / reduce the environmental impacts of its activities, aimed to respect both the interests of market and the community legislation, with particular reference to the Marine Strategy Framework Directive. The latter rule requires the member states of the EC to achieve the ecological status of “good” (Good Environmental Status – GES) for their marine waters by 2020.

The use of specific “integrated multi-trophic aquaculture systems” (Integrated multi-trophic aquaculture – IMTA), contextualized at the local level, could represent the main instrument to harmonize the development of this growing industrial sector with the achievement of the environmental quality objectives defined by the community policies.