sardines (Stuart 2009). While there is no direct evidence, there is concern that fishmeal will compete with human food consumption, especially in regions where small pelagic fish are important components to diets, typically in Africa, Asia and Latin America, regions that also have the highest number of hungry people in the world (WorldFish 2011; Tacon and Metian 2009). Intensive aquaculture practices may also lead to environmental degradation and changes in local ecosystems. For example, intensive fish farming pollutes waters with uneaten feed, fecal and metabolic waste from the fish. This can lead to over-fertilization (eutrophication), that can cause algal bloom and oxygen deprived dead zones, harmful to both wild and farmed species (Schmidt et al. 2013). When alien fish species, raised in aquaculture systems, enter the natural habitat, either through release or escape, these non-native fish can cause loss of native stocks through predation, competition or transmission of diseases (Naylor et al. 2000). In spite of these criticisms, many fish farms are more environmentally friendly than other food producing systems. For example, aquaculture has lower nitrogen and phosphorus emissions than beef and pork. It takes 15 times less feed to produce one kilogramme of carp compared to one kilogramme of beef (Schmidt et al. 2013). According to the FAO (2011b) “responsible aquaculture can provide substantial environmental benefits, such as recovery of depleted wild stocks, preservation of wetlands, desalinization of sodic lands, pest control, weed control, and agricultural and human waste treatment”. About one-third or 20 million tonnes of all farmed fish is produced without artificial feed (FAO 2012b). Mussel farming relies on natural feed from the ocean and intensive mussel farming has been shown to be beneficial for the ecosystems as mussels filter water to sieve out tiny particles of food, counteracting over-fertilization and algal blooms (Schmidt et al. 2013). As the aquaculture sector grows, it is crucial that the environmental and social concerns are thoroughly addressed and that sustainable management practices are adopted (Diana et al. 2013). If managed sustainably, aquaculture can be part of the solution to feeding a growing human population as well as to restoring the dwindling fish stocks, since increased investment in aquaculture can potentially take the pressure off wild fish stocks, giving them time to recover (Asche and Khatun 2006).
As yields from captured fish are leveling out, the question has been raised as to whether aquaculture will be able to provide the extra fish yields needed for the world’s expected 9.6 billion inhabitants in 2050. According to the FAO (2013e), 62.7 million tonnes of seafood were produced for human consumption in 2011 through aquaculture. With an annual growth rate of 8.8 per cent between 1980 and 2010 (FAO 2012b), no other food production sector has grown as fast in the past 40 years (UNEP 2012). Aquaculture is gaining a dominant position within fisheries with a 40 per cent share of the total fish production (FAO 2013e) and experts predict that aquaculture will gain an increasing role in the global food supply (FAO 2010b). Asia is the leading producer in the sector contributing nearly 90 per cent of all aquaculture production. Eight out of the top 10 aquaculture producing countries are found in Asia, with China as the main producer with 38.6 million tonnes, followed by India, Vietnam, Indonesia and Bangladesh (FAO 2013e). In addition to being an important contribution to national economies, aquaculture is an important provider of nutrient-rich food to the Asian region. The majority comes from large-scale commercial production, but Asia also has long traditions of fish farming for local food production. In several Asian countries, fish is traditionally farmed on flooded rice fields (Halwart and Gupta 2004). In fact, developing countries are the main producers of aquaculture with as much as 80 per cent of all aquaculture taking place in developing countries. This highlights the sector’s importance for economic development, poverty reduction and food security (Asche and Khatun 2006). In Africa, aquaculture production is still low with only 1.4 million tonnes produced in 2011 (FAO 2013e). Scientists (Schmidt et al. 2013) as well as international organizations such as the FAO (Moehl et al. 2008) and WorldFish (2012) are promoting the potential for aquaculture in Africa, and predict that it can play an increasing role in supplying food for the continent. In spite of its future prospects, aquaculture has been criticized. Perhaps one of its most censured practices is feeding farmed fish fishmeal made up of large proportions of wild fish as this increases pressure on current forage fish stocks (Naylor et al. 2000) and their dependent species. The ratio of wild fisheries inputs to farmed fish output is currently 0.63, though it takes about five kilogrammes of wild fish to produce 1 kilogramme of salmon (Naylor et al. 2009). Fishmeal is usually made up of small pelagic fish such as anchovies, herring, sand eels, mackerels, menhaden and