We have reached the limit for how many fish we can sustainably harvest from the oceans. In a report from 2021, the Food and Agriculture Organization of the United Nations estimated that 37.7 per cent of the world's fish stocks were overfished. This means that the stocks were caught at a faster rate than they could naturally reproduce.
"90 million tonnes is the amount we can extract from the oceans in a reasonably sustainable way. There are no more fish available beyond that. The global population is constantly increasing. This means that we need more protein—including fish—which we're also encouraged to eat," says Per Bovbjerg, Professor at DTU Aqua.
The alternative to the severe shortage of fish is aquaculture—fish farming in the sea or on land. The fish farming industry is currently experiencing fast growth. In 2022, aquaculture surpassed ocean fishing in supplying the largest quantity of fish for global consumption accounting for 51% of the total supply.
New gentle fish farming
While fish farming offers an alternative to depleted marine stocks, conventional farming methods can harm the surrounding aquatic environment. Fish farms discharge nutrients (feed residues and excrement) that can affect plant and animal life and can cause algal blooms, oxygen depletion, and fish death.
At North Sea Science Park in Hirtshals, researchers from DTU Aqua are therefore testing new technologies for more sustainable aquaculture. The technology showing the greatest progress involves so-called RAS systems (recirculating aquaculture systems), which are closed land-based facilities that significantly reduce the discharge of harmful nutrients into the aquatic environment. Although RAS systems have already been established in the industry, they are costly to operate. Research is therefore focused on developing new methods to make the technology more cost-effective, while safeguarding the climate and aquatic environments.
