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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
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).
Aquaculture