Many of the fish farmed more intensively around the world today are carnivorous, for example Atlantic salmon, trout, sea bass,[disambiguation needed ] and turbot. In the development of modern aquaculture, starting in the 1970s, fishmeal and fish oil were key components of the feeds for these
species. They are combined with other ingredients such as vegetable proteins, cereal grains, vitamins and minerals and formed into feed pellets. Wheat, for example, is widely used as it helps to bind the ingredients in the pellets.
Other forms of fish feed being used include feeds made entirely with vegetable materials for species such as carp, moist feeds preferred by some species (easier to make but more difficult to store), and trash fish — that is fish caught and fed directly to larger species being raised in aquaculture pens.
Hatchery feeds
Specialised feeds are produced for fish hatcheries. In species such as salmon and trout, the newly hatched fry first feed from their yolk sacs and then can be fed with starter feeds. Marine species such as sea bass, sea bream, flounders and turbot consume the nutrition in their yolk sacs during the first few days post hatching and then are fed for several weeks on live prey, in the form of rotifers and brine shrimp (Artemia). Special feeds can be used to enrich the nutritional value of the prey. Rotifers are usually bred in the hatchery while brineshrimp are generally collected from the wild, e.g. salt lakes. Manufactured feed alternatives to brine shrimp are becoming available, offering more consistent nutrition and improved sustainability as demand increases with the growth of aquaculture.
Development of manufactured feeds
The development of dry pelleted fish feeds to date has two themes. One theme is on improving digestibility and refining the balance of nutrients to match the needs of the different species of fish more precisely at different periods of development. The other theme is to improve the sustainability of the ingredients used. This is being achieved mainly by identifying additional sustainable sources of ingredients, in particular to reduce the need for fishmeal and fish oil. Improving the efficiency of feeding also contributes to sustainability.Sustainability
Fishmeal is a brown, flour-like material made by specialist producers that cook, press, dry and grind the fish. The fish oil is effectively a by-product of this process that proves to be a rich source of energy and fatty acids for fish, including the important long-chain omega-3 fatty acids EPA and DHA now linked to the health benefits associated with eating oily fish such as salmon and mackerel. Fish in general also are good sources of many vitamins and minerals and are often recommended as part of a healthy diet by governmental food agencies.[3][4][5][6]
Because the catches of wild fish must be managed at sustainable levels to ensure the stocks continue to be viable, the available supply of fishmeal and fish oil from these resources will not increase.
The global demand for fish from consumers around the world is increasing. Reasons include the growing population, rising average incomes and greater awareness of fish as part of a healthy diet. The yield from the wild catch cannot be increased sustainably, therefore, in the opinion of observers such as the Food and Agriculture Organization (FAO) of the United Nations, aquaculture must fill the gap. Currently the supply of fish from aquaculture approximately matches that from the wild catch, according to FAO figures.
The current drive in research and development is enabling this to happen by supplementing fishmeal and fish oil with vegetable proteins and oils, while ensuring the fish continue to provide the important health benefits for consumers.[7] Other potential raw material resources such as algae are also being explored.
Modern fish feed
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