Aquaculture is not a solution to overfishing. Traditional forms of aquaculture can and do make substantial contributions to food supplies in areas of the world where food needs are acute, but these need to be sustainable.

Many modern aquaculture practices emphasise the unsustainable production of species for high-value export markets. Rapid development and expansion of intensive aquaculture for species such as salmon and shrimp has, for example, resulted in widespread degradation of the environment and the displacement of coastal fishing and farming communities.

Unsustainable aquaculture also negatively impacts on the food supplies and food security of developing coastal countries. Aquaculture development often blocks access to common lands, used by local people for fishing and cleaning (collecting of seafood from the ground), and takes away traditional food sources, for use in fishmeal and oil production for aquaculture production. 

What are the main problems with aquaculture? 

Unsustainable aquaculture can devastate our oceans and the environment and impact on local people's food and security.

Some examples include:

• the extraction of marine species from oceans, including wild juveniles vital for future stock growth, increasing the burden on wild fish stocks and having major food security implications;
• fishmeal and so-called 'trash fish' used for feed production - often the main food for local people - taken for use in aquaculture ponds;
• the release of organic wastes (that, for instance, act as plant nutrients for harmful algal blooms) and toxic effluents into the oceans;
• the destruction of coastal ecosystems, displacement of coastal communities and depletion of fresh water sources to build aquaculture ponds.

What kind of aquaculture is sustainable?

There are no species that are sustainable as such. The sustainability of a species depends on its feeding and lifecycle habits, as well as the farming operation. Only species that are plant eaters, who can breed in captivity, and whose farming does not produce high levels of nutrient output can be cultivated sustainably.

There are a number of conditions an aquaculture operation must adhere to in order to be sustainable. Among other things, an aquaculture operation can only be regarded as sustainable if it:

• is continually moving towards plant-based feeds originating from sustainable agriculture;
• does not use fishmeal or fish-oil-based feeds from unsustainable fisheries and does not represent a net loss in fish protein yield;
• does not use wild-caught juveniles;
• only cultivates species that are native in open water systems, and then only in bag nets, closed-wall sea-pens or equivalent systems (if there is cultivation of non-native species, it must be restricted to land-based tanks);
• does not result in negative environmental impacts in terms of discharges and effluents to the surrounding areas;
• does not result in negative effects to local wildlife (plants as well as animals) or represents a risk to local wild populations;
• does not use genetically engineered fish or feed;
• uses stocking densities that minimise the risk of disease outbreaks and transmission;
• does not deplete local resources, for example, drinking water supplies and mangrove forests;
• does not threaten human health;
• supports the long-term economic and social well-being of local communities.

Achieving sustainability requires adhering to a full set of measures and cannot be reached through simply implementing one or two. 

How can consumers be sure that the products they buy come from sustainable and fair aquaculture?

No current certification scheme covers all of the issues essential to ensure products come from sustainable and fair aquaculture operations. It is the responsibility of retailers to ensure that the products they buy come from operations adhering to the conditions described above. Retailers must, until a reliable certification system is in place, communicate to their customersthe sustainability of their products.

In turn, customers must also challenge their retailers to ensure that their supplies stick to all of these conditions. Unless consumers can be assured that products come from sustainable operations, they should not buy them.

The Greenpeace report, Challenging the aquaculture industry on sustainability, offers advice to the industry on becoming sustainable, and provides guidelines to retailers and seafood suppliers on how to ensure they only buy aquaculture products from sustainable operations.