17/07/2008 11:24 amAquaculture is defined as the cultivation of cultivation of aquatic (freshwater and marine) plants and animals of commercial importance.
Aquaculture is the sector of the food industry that has the highest rate of growth in the world, mainly for the two following reasons:
- The demand in fish protein keeps expanding, due to the worldwide demographic growth and food preferences turning more towards sea products. The average consumption of products of aquatic origin was 16kg (≈ 8 pounds) per person annually in 2004 (187 kg per person in the Maldives, 66 kg in Japon, 26 kg in European union and China).
- Wild fishery stocks are decreasing, since ecosystems have reached their maximum catch potential for a number of species. The sea fish landings fluctuated around 80 to 90 million tonnes per year since the mid eighties.
Contribution to “food safety”
Aquaculture offers a diet rich in high quality proteins, essential fatty acids, together with vitamins and minerals. Approximately 56% of the world’s population obtains at least 20% of its supply in animal protein from fish, and in some countries this dependency is almost total. Ninety percent of the production derives from small fish farms. Fresh water fish account for over half of the total farmed-raised fish. These are mainly carp species, produced in China and the rest of Asia. Western Europe countries provide 55.6% of salmonids of higher commercial value. In developing countries, aquaculture improves food safety and contributes to reducing poverty. It provides work and a mean of survival to millions of people. In Asia, it offers a direct source of employment to some 12 million people, among which 4,000,000 in China and 700,000 in Vietnam.
Salmons on the run
Studies were conducted in Norway (Erik Petersson, national management for the fishery of Sweden, for the environment briefs of the INRA – national institute for agronomic research - n° 26), in farm raisings of Atlantic salmon. Each year, several hundreds escape their cages. It is estimated that within the 1989-1996 period, farm raised fish that ran away represented 34 to 54% of the catches along the coast. In addition to the competition for food that is brought about for the wild salmons, it disturbs their reproduction cycle. The runaways spawn later, and damage the nests of their wild fellow creatures. And because they have a lower reproduction rate, they probably do not compensate what they destroy.
The impact of aquaculture on the environment depends on the culturing methods elected and especially on level of intensification. Those impacts mainly consist of:
- Increasing pressure on fisheries in order to obtain fish meal, fish oil, and other ingredients for food products intended for carnivorous and omnivorous species (salmon, sea bream, tilapia, carp…). Aquaculture may consume 53% of the available fish meal, and 87% of the world’s production of fish oil. From three to five kg (≈ six to ten pounds) of fish caught in natural environment are necessary to produce one kg (≈ two pounds) of farm raised fish. In 2004, this type of fishery, so-called industrial fish meal industry, extracted around 1.5 million tonnes of fish (e.g. anchovies, mackerels…).
- Accumulation of sediments from ill-planned nutritional strategy can lead to the increased organic enrichment and thus elevating risks of eutrophication of lakes or coastal areas.
- Further contamination of the environment through medicines and chemical substances used in farm operations (e.g. antibiotics, hormones, pesticides).
- Conveyance of pathogenic agents to wild species due to introduction of exogenous species.
- Competition for the resources among other anthropogenic activities accompanied, in some cases, by their depletion (e.g. water).
- Risks related to the potential escape of farm-raised fish, resulting in genetic drifts, ecological interactions with wild fish.
- All the above factors may threaten general biodiversity, such as benthic communities (animals living at the bottom of the water).