Sustainability issues range from the minimisation of energy use on farms and the reduction of nutrient emissions to the environment, to the increased use of sustainable fish feed ingredients, the minimisation of escapees, disease outbreaks and parasite infestations, and the supply of juveniles and recruits from sustainable sources. Aquaculture is often seen as having an effect on biodiversity (the variety and diversity of the living world) through the introduction of exotic species or domesticated escapees, and by its impact on the wider environment through the release of wastes. Both reproductive and health aspects are associated with these issues. However, carefully managed aquaculture may actually enable an increase in the biodiversity of a particular area or ecosystem.

A high demand for fish protein

Fish protein makes up around 15% of the world total protein intake in the human diet. Globally, more than 2,6 billion people receive at least 20% of their dietary protein intake from fish. Demand for seafood products has exceeded supply from wild catches and as a consequence production from aquaculture has been increasing rapidly over the past 20 years. Nearly 50% of global fish supplies originated from farmed sources in 2004. Growth has been especially strong in Asia, and in particular in China, which accounts for 70% of world production (and 50% of the world market value), followed by the rest of the Asian-Pacific region and Western Europe (principally Norway).

In terms of fish species, aquaculture primarily concerns freshwater species (carp species being the most prevalent), followed by bottom-dwelling marine species, then pelagic marine species. The marine species farmed are mainly those of high commercial value. Atlantic salmon farming in particular has experienced a world-wide success in temperate zones. It is accompanied by a scientific and technical force, which has allowed for rapid advances in terms of alimentation, reproduction and adaptation to captive conditions. However, there are many problems related to environmental impact, availability of raw materials / feeds and traceability.

Pressure on certain fish populations and ecosystems

Reproduction of many economically important species cannot be controlled successfully in captivity. This is the case, for example, for the tuna, eel and sturgeon. Their wild populations are placed under great pressure by the fish farming industry, as young fish are collected from the wild to be grown-on in farms before being marketed.

Differences in legislation, control and public pressure between countries and continents

Wide variations exist between countries concerning the application of hormones, medecines, feed types, farming systems and impact assessments. Public opinion on fish welfare and environmental protection is stronger in Western Europe, and in more affluent countries in general, than in developing countries. As a result, European farmed fish products face great competition from cheaper imported foods and are likely to develop towards a focus on quality rather than quantity in the long term.

Problem of feeding carnivorous fish species

Rapid aquaculture growth increases pressure on fish caught for feed. Therefore an important environmental question is the extent to which fishmeal and fishoil can be replaced with alternative, sustainable, sources of protein and fats.

For further information click on the link below: 

Assessing and ensuring sustainability in fish farming