Likewise, intensive fish farming causes downstream nutrient pollution. Keeping fish healthy in their tanks on a full-scale fish farm requires that the water be changed on a regular basis, up to several times a week. This calls for huge amounts of freshwater and generates substantial wastewater emissions, in turn creating its own set of sustainability concerns.
The challenge of feeding 10 billion people by 2050 is inherently linked to water security. According to FAO, fish will be one of the most important protein sources to feed the world’s growing population. Unregulated, this growth could result in vastly increased freshwater demand and increased pollution in rivers and oceans as effluents from wastewater are discharged from farms. The high-pollution, water-exigent nature of intensive inland fish farming could become a major constraint on future food production, in particular in areas that already suffer from dry conditions. In addition, the bulk of inland fish farming producers (aside from Norway and China) operate in developing countries, making the sustainability challenge an economic one as well.
A pilot farm, where lemna is grown out of fish farming waste water. Photo: MicroTERRA