Agriculture and Environment: Salmon
Environmental Impacts of Production: Pressure on Wild Fisheries
However, because salmon are carnivorous, they require a diet high in fish meal and fish oil.
Fish oil use is now dominated by aquaculture, which takes 60% of total production (FAO 2000). Salmon aquaculture is by far the largest user. Analysts have suggested that aquaculture will use more than 90% of fish oil by 2010.
At this time, some 20-25% of annual global seafood supply is converted to fish meal and fish oil (Packard Foundation 2001). Though a relatively new industry in 1994, the carnivorous aquaculture farms used approximately 15% of the global fish meal output (Ellis and Associates 1996). By 1997 aquaculture used 33% of fish meal supplies (Jacobs et al. 2002).
Feed formulation - energy and weight gain
Changes in feed formulation have focused on oil to provide energy for fish to swim and meal to result in weight gain. Salmon feed can contain up to 40% fish oil. This has increased from 8% in 1979 (Staniford 2002). Net-cage rearing of 1 kilogram of salmon is estimated to use anywhere from 4 to 5.5 kilograms of wild fish.
While this is probably a far better ratio than salmon in the wild (where the ratio could easily be 8 to 1, 10 to 1, or even higher), responsible businesses must strive to use finite resources more efficiently. Finally, the tradeoffs for this issue are further compounded if the fish used to make fish meal could be consumed directly by people rather than converted to more high value products for wealthier consumers.
High costs fo salmon feed
Feed accounts for 30-50% of a salmon producer's annual expenses. Because of the high quantities of fish meal and fish oil used, farmers look for low prices for these products, putting pressure on the South American fish-meal industry.
Japan, Chile, Peru, and the Commonwealth of Independent States (former Soviet constituent states) account for approximately two-thirds of all fish and meal production. Three species of fish (anchoveta, sardine, and jack mackerel) constitute 85% of South American fish meal production, and they are susceptible to large fluctuations in population due to El Nino.The anchoveta population collapsed in the 1970s, 1980s, and 1990s. When this happens, it puts more pressure on other species to make up the difference for industries that are dependent on feeds based on fish meal.