USDA - ARS
All commercially important marine fish populations are considered currently fully exploited or overexploited by USA and international fisheries management agencies, with the possible exception of the Alaskan fishery. Seafood consumption, however, is increasing due to the influence of aquaculture production. Over the next 20 years, aquaculture production must increase by 500% to meet expected demand of fish for human consumption. Fish meal and fish oil, which are produced from capture fisheries of industrial species not used for direct human consumption, have been primary ingredients of fish feeds, but there are concerns that supplies are insufficient to meet the growing demand to produce fish feeds. In fact, limited production of fish meal and fish oil is predicted to limit industry expansion by 2013 (Tacon 2003). These products are also costly, variable in quality and availability, and their continued rate of production is considered by some to be unsustainable. To allow for the continued expansion of aquaculture, alternate sources of protein and oil must be developed and production efficiencies must be increased. Developing new diet formulations in which fish meal and fish oil are replaced with alternative ingredients can reduce fish feed cost and variability and move the aquafeed industry to a more sustainable foundation. However, some alternative ingredients can create problems with reduce feed intake lower feed digestibility, cause metabolic alterations or health problems in fish and reduce growth rates of fish. Plant-derived ingredients, and other alternative sources, must be modified to improve nutritional quality, reduce levels of anti-nutrients and meet specifications for aquafeeds by genetic selection of the plant, post-harvest processing, and feed formulation and processing.
Feed costs often represent greater than 60% of the production costs, so cost effective diets are essential. All of the nutrients such as nitrogen and phosphorus release from a fish farm originally came from the feed. Nutritionists formulate feeds, determine the proper mixture of ingredients, to match the nutrients required by the fish with those supplied in the diet. An excess of nutrients increase effluent nutrient discharge and is inefficient and expensive, and a deficiency of nutrients will decrease animal performance which again is expensive.