Other than the largely unknowable but nonetheless serious impacts of global warming and climate change, among the more pressing issues in fisheries and livestock production is the replacement of fish meal and oil, now comprising a large portion of salmon, trout, bass and other carnivorous cultured fish feeds. Many other animal diets, as well as for most other cultured fishes and shrimps, include substantial quantities of fish meal and oil for the healthful omega 3 lipids and easily digestible protein. An estimated 2.8 mmt fish meal and 1.0 mmt fish oil are currently utilized. This quantity is rendered from much larger quantities of ocean stocks of plankton-feeding fishes such as menhaden, sardines, herrings, etc. Although not a large portion of these are sought for human consumption, they are essential parts of the marine food chain that lead to production of high value predator fishes and other sea life, such as seabirds, including penguins, and mammals. In addition, biocontrol of harmful algal blooms may be reduced by reduced planktivore populations, as has been suggested for menhaden on the U.S. east coast. The healthful lipids in the fish meal and oil are the result of bioconcentration of these compounds originating with algae. Along with the bioconcentration of these beneficial compounds are minute quantities of other compounds from ocean waters that are undesirable, such as metals and industrial compounds. Thus, objections are raised not only to use of fish meal and oil, but to the inadvertent inclusion in diets of these compounds.

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