The global production of wild and farmed fish is 200 million tons. Farmed fish production has exceeded 110 million tons and is becoming increasingly important. Fish farming can be divided into marine and land-based farming. Land-based farming has the advantage of not using seawater, making it easier to prevent fish disease. The longer the period of marine farming, the greater the risk of natural disasters and disease. By maintaining constant environmental conditions such as water temperature and oxygen levels, land-based farming allows for stable shipments even in the summer. Once land-based farming operations are on track, a stable supply of high-value-added fish such as salmon can be expected. Taking advantage of its ability to adapt to changes in the ocean, the shift from marine to land-based farming appears likely to continue.
Attracted by the benefits of land-based aquaculture, an increasing number of companies are embarking on this endeavor. As of 2024, there were over 660 companies involved in this type of farming. While there are benefits, there are also challenges. The biggest challenge to the widespread adoption of land-based aquaculture is cost. The reality is that 70% of aquaculture costs are feed. Furthermore, compared to marine aquaculture, it requires more initial investment in the aquaculture plant and maintenance costs, such as electricity for water circulation. The fish used as feed for aquaculture are called bait fish. Famous locations and species for bait fish include anchovy fishing in Peru and herring fishing in Europe. Another source is soybean meal (a type of soybean meal) left over from oil extraction. The problem is the rising cost of these feeds. Another challenge is growing fish and shipping them at the quality the market demands while keeping feed costs down.
A model that effectively solves this issue is emerging. It is a combination of fish farming and hydroponic lettuce cultivation, taking place in Ofunato City, Iwate Prefecture. A notable feature of this model is its circular farming method, which involves simultaneously cultivating fish and growing them hydroponically through water circulation. This model involves simultaneously cultivating 1,000 sturgeon and growing leaf lettuce. The waste from the farmed sturgeon is processed and used as fertilizer for hydroponic cultivation. In this facility, bacteria are used to break down the waste from the fish in the tanks into plant nutrients. The water that has been broken down into nutrients is then used as fertilizer for the lettuce. Here, lettuce is grown hydroponically without the use of chemical fertilizers or pesticides. By using the fish waste as fertilizer for the lettuce, the water is purified and returned to the fish tanks, practicing a recycling-based farming method. By eliminating the need for chemical fertilizers and pesticides and circulating the water, the burden on the environment is minimized.
