Sunnuntai 25.3.2018 klo 20:24
To be sustainable and ecological, food production should take place near the place of consumption. So, in the best possible case fish and vegetables are produced in towns next to where they are consumed. This is nowadays possible. The news have carried items showing vegetable production in city buildings using irrigated individual boxes. Similarly, it is nowadays possible to recirculate water for aquaculture so that fish production is possible in an establishment next door fish restaurant.
It is actually quite incredible how recirculation has improved water quality in several cases. In 1970's paper and pulp mill industry was polluting Finnish and Swedish waters so that even recently some persistent organic pollutants have occurred in the Baltic Sea at concentrations, which have exceeded EU norms for food. And this has been the case, even though the levels are 1/5-1/10th of values in 1970's-80's. Since then the industry has started to recirculate water (and stopped the use of the toxic compounds), so that nowadays the mills are almost closed systems, and the water quality, e.g., in Saimaa and near Äänekoski has improved immensely. Also, traditional aquaculture causes significant eutrophication. It can be completely avoided in the recirculating aquaculture systems, where bacteria in biofilters use up all the eutrophying material - in fact acting as small water cleaning units.
So, future aquaculture can be sustainable and ecological, if it is based on recirculation.