How much fish does a fish need?

Aquaculture operators aim to raise as many fish as they can with as little feed as possible. Large predators such as salmon, however, require comparatively large amounts of feed to produce body mass. The FIFO ratio is the measurement of the amount they need. It indicates how much wild fish must be used as animal feed in order to produce an equivalent weight unit of farmed fish. If 1 kilogram of wild fish is used to produce the feeds of 1 kilogram of farmed fish, the FIFO ratio is 1 (1 kilogram/1 kilogram = 1). Any value more than 1 means that more than 1 kilogram of wild fish is required to produce 1 kilogram of farmed fish. In the mid-1990s the FIFO ratio for salmon was 7.5, while today the figure is between 3 and 0.5. Our increased knowledge of efficient feeding and improved feed formulations has contributed to this development. Improved feeding efficiency as expressed by the FIFO ratio saves fishmeal and enables more farmed fish to be produced with less fish in feeds. Studies have shown that this technological adaptation from aquaculture industry is vital if we are to meet current and even larger per capita consumption rates. For example, if the current global consumption rate of fish of 17 kilogram per capita and year is to be maintained by 2050, aquaculture would have to reduce its FIFO ratio from approximately 0.6 in 2008 to 0.3 units of marine fish to produce a unit of farmed fish. The most recent assessments and projections indicate that this value is achievable if aquaculture continues to improve its efficiency at the current pace. This seems to be possible – not only by optimizing feedstuffs, but also by breeding fish species which are less demanding. Catfish already achieve a ratio of 0.5, tilapia of 0.4 and milkfish, a popular fish group in Asia, a ratio of 0.2, which would mean that 5 units of cultivated milkfish are produced using one unit of marine fish.