Aquaculture is expected to become the primary source of seafood by 2030, as demand grows from an expanding middle class population and stocks of wild fish decline.

Aquaculture is thought to more sustainable than other animal production methods. Fish turn feed into protein 4 and 13 times more efficiently than pigs or beef cattle, respectively. Furthermore, they generate half to two-thirds less nitrogen per tonne of protein produced than pigs or cows, respectively, while fish-generated phosphorus is roughly 15 percent less than pigs and 55 percent less than beef cattle.

As this industry grows into a large-scale producer of food, so does concern over its impacts on the environment.

Several certification programs have made progress in defining best practice production. Environmental practices include mangrove and wetland conservation; effective effluent management and water quality control; sediment control and sludge management; soil and water conservation; efficient fishmeal and fish oil use; responsible sourcing of broodstock and juvenile fish; control of escapes and minimizing biodiversity and wildlife impact.

Effective biosecurity and disease control systems are important, as are minimising use of antibiotics and pharmaceuticals, microbial sanitation, efficient and humane harvest and transport and accountable record-keeping and traceability.

In addition to the production of fish, aquaculture brings benefits to farmers using certain species of fish to fight rice pests and to boost rice yields for example. Mud from the bottom of fish ponds has also been shown to be a useful mineral-rich fertiliser.

With industry growth comes the increased risk of disease. In 2010, hepatopancreatic necrosis syndrome, devastated shrimp farms throughout China, Vietnam, Malaysia and Thailand.

The FDA issued two countrywide alerts requiring mandatory testing for antimicrobials for aquaculture-raised seafood before entry into the US — one in 2007 for seafood from China, and another in shrimp from the Malaysian peninsula in April 2016.

Further concerns about the industry’s rapid expansion focus on ‘ranched’ fish such as tuna, which feed on vast quantities of live pelagic fish (anchovies, sardines and mackerel). It takes about 20 kg of feed to produce 1kg of tuna ready for a sushi bar.

Innovation has centred on developing alternative feedstocks. Non-fish eaters such as catfish and tilapia can be raised on plant-based diets. Shellfish are another good option, since they feed by filtering particles out of the water and can be easily farmed in clean water where they collect their own food.