It is estimated that about 31.5 million tonnes of farmed fish and crustaceans (46.1 percent of the total global aquaculture production in 2008) is dependent upon the supply of external nutrient inputs provided in the form of fresh feed items, farm-made feeds or commercially manufactured feeds. Total industrial compound aquafeed production increased more than threefold, from 7.6 million tonnes in 1995 to 29.2 million tonnes in 2008, with production growing at an average rate of 11.0 percent per year. Aquafeed production is expected to continue growing at a similar rate to 71.0 million tonnes by 2020. Although current estimates for industrially produced aquafeed for the period 2007–2010 vary between 24.4 and 28.9 million tonnes, aquafeed volume represents only 4 percent of the total global animal feed production of the over 708 million tonnes in 2009. In contrast to compound aquaculture feeds, there is no comprehensive information on the global production of farm-made aquafeeds (estimated at between 18.7 and 30.7 million tonnes in 2006) and/or on the use of low-value fish/trash fish as feed, with 2008 estimates for China at 6 to 8 million tonnes.
Fed aquaculture production, in particular, of higher trophic level finfish and crustaceans (includes marine shrimps, salmonids, marine finfishes, eels) are largely dependent upon capture fisheries for the supply of their major dietary source of protein and lipids. For example, on a global basis, it is estimated that the aquaculture sector consumed 3.72 million tonnes of fishmeal (60.8 percent of global fishmeal production) and 0.78 million tonnes of fish oil (73.8 percent of global fish oil production) in 2008; it was 3.84 million tonnes of fishmeal (or 68.4 percent of global production) and 0.82 million tonnes of fish oil (or 81.3 percent of global production) in 2007. Despite this continued dependence of aquaculture production on fishmeal and fish oil, there remains a wide variation in fishmeal and fish oil usage between major producing countries for individual farmed species. This variation mainly reflects differences between countries concerning the selection and use of fishmeal and fish oil replacers from plant sources or by the use of land animal proteins and fats in feeds for high trophic-level fish and crustacean species.
The total use of fishmeal by the aquaculture sector is expected to decrease in the long term. It has gone down from 4.23 million tonnes in 2005 to 3.72 million tonnes in 2008 (or 12.8 percent of total aquafeeds by weight), and is expected to decrease to 3.49 million tonnes by 2020 (or 4.9 percent of total aquafeeds). The reasons for this are the diminishing amount of fishmeal and fish oil supplies owing to tighter quota setting and additional controls on unregulated fishing and the increased use of more cost-effective dietary fishmeal replacers. On the contrary, the use of fish oil by the aquaculture sector will probably increase in the long run albeit slowly; total usage will increase by more than 16 percent, from 782 000 tonnes (2.7 percent of total feeds by weight) in 2008 to the estimated 908 000 tonnes (1.3 percent of total aquafeeds for that year) by 2020. Increased usage will shift from salmonids to marine finfishes and crustaceans because of the current absence of cost-effective alternative lipid sources that are rich in long-chain polyunsaturated fatty acids. Increasing volumes of fishmeal and fish oil are likely to come from fisheries by-products, extracted from both wild capture and farmed fish. Estimates have been made that around 25 percent of fishmeal production in 2007 came from by-products. This will grow as it becomes increasingly viable to process this material.
It is estimated that the total usage of terrestrial animal by-product meals and oils within compound aquafeeds ranges between 0.15 and 0.30 million tonnes, or less than 1 percent of total global compound aquafeed production – clearly, there is considerable room for increased usage. In addition to meat meal, or, to a lesser extent meat and bone meal, ingredients such as blood meal, poultry by-product meal and poultry oil have all been very effective in feeds for a number of aquatic species.
Soybean meal is the most common source of plant proteins used in compound aquafeeds, with feeds for herbivorous and omnivorous fish species and crustaceans usually containing from 15 to 30 percent soybean meal, with a mean of 25 percent in 2008. In global usage terms, and based on a total compound aquafeed production of 27.1 million tonnes in 2007, it is estimated that the aquaculture feed sector consumed about 6.8 million tonnes of soybean meal (25.1 percent of total compound aquafeeds by weight). Other plant proteins being increasingly used include corn products, pulses, oilseed meals and protein from other cereals products.
Alternative lipid sources to fish oil are being used in greater amounts. Key alternatives include vegetable oils, preferably those with high omega-3 contents, and poultry oil. The use of oil from farmed fish offal is also a potential omega-3 source for other farmed fish. The production of marine microalgae or bacteria with very high contents of highly unsaturated fatty acids is currently expensive for use in most aquaculture feeds, but more cost efficient production methods will change this.
Prices for food and feed ingredients have been rising and are likely to continue to rise owing to the increasing demands from an increasing population, the diversion of some grains for use in biofuels, the increasing costs of production and transport, and the changes in global trade owing to the demand of food and raw materials from China and other emerging economies. The focus on carbohydrate-rich fractions for production of biofuels may indeed provide an opportunity to use protein fractions for feed ingredients.
Although current discussion on the use of marine products as aquafeed ingredients focuses on fishmeal and fish oil resources, the sustainability of the aquaculture sector is more likely to be linked with the sustained supply of terrestrial animal and plant proteins, oils and carbohydrate sources for aquafeeds. This is because a significant proportion of aquaculture production is of the non-carnivorous species. Therefore, aquaculture producing countries should place more emphasis to maximize the use of locally available feed-grade ingredient sources and use nutritionally sound and safe feed ingredients that can be sustainably produced and grow with the sector.
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