Aquaculture environmental impacts

Where – and how – was my fish grown?

Chances are you will need to ask this question more and more. Historically, capture fisheries (fish caught in the wild) have been the most prominent source of traded fish. However, capture fisheries volumes have levelled off in the past decade and aquaculture (the breeding, rearing, and harvesting of plants and animals in all types of water environments) is increasingly looked on to meet the increasing global demand for fish. In fact, aquaculture already produces almost half of all fish for human food – and this share is expected to increase to more than 60% by 2030! Behind this growth, there are some important sustainability issues that need to be considered.

Aquaculture production is one of the fastest growing food sectors globally – it increased at an annual rate of 6% from 2000-2012. In 2012, global aquaculture production achieved an all-time high production of over 90 million tons (live weight equivalent) – consisting of 66 million tons food fish and 24 tons of aquatic algae. Important species farmed globally include salmon, trout, carp, tilapia as well as shrimp, to name but a few, produced in a diversity of habitats – fresh or salty water, river, coast or sea, pond cages or net pens.

Aquaculture contributes to increased food security globally and also has the potential to reduce pressure on wild fish numbers as well as terrestrial ecosystems by providing an alternative source of protein to meat. Further, at a global scale the sector provides employment and supports livelihoods of millions of people – fish is actually one of the most traded food commodities globally. However, such a rapid growth of aquaculture at such a broad scale inevitably means the sector faces some sustainability challenges. Here I highlight some of the core issues and future needs.

 

FEED

A major challenge facing the aquaculture industry is its reliance on fishmeal and fish oil used for feed. The primary source of fish used for the production of these feeds is captured fish. In fact, fish and crustacean aquaculture is the largest global consumer of captured, non-food products (mainly as fish meal and fish oil). A future challenge is thus to further develop sustainable alternative feed sources in order to reduce reliance on wild fish stocks.

 

WATER and LAND RESOURCES

As with other animal production systems, aquaculture is reliant on land, water, energy and feed resources – all of which invariably have environmental impacts. Inland, freshwater aquaculture uses large volumes of freshwater for ponds. Irrigation water for land-based feed production also contributes to very large water consumption by the sector. Aquaculture systems are often located in coastal environments which can be sensitive ecosystems and important from a biodiversity perspective, for example mangroves and wetlands. A future challenge is thus to ensure that sites for aquaculture development are carefully chosen, with minimal environmental and social consequences.

 

POLLUTION AND MEDICINE USE

Similar to land-based animal production systems, aquaculture entails raising large numbers of fish together in a crowded space in an unnatural environment – conditions which allow for the spread of diseases and parasites between fish. Antibiotic and hormone use and loss to the environment represents a serious challenge, as is the loss of fish waste, uneaten feed and pesticides to the surrounding environment.

 

BIODIVERSITY and ESCAPES

The escape of farmed fish into the surrounding environment from open systems can cause an introduction of non-native species (with a variety of consequences for biodiversity) as well as introducing new parasites and diseases.

Many efforts are being made to improve the sustainability performance of aquaculture systems, in particular, through a host of initiatives and certifications, such as the Aquaculture Stewardship Council, Global GAP, and the Global Aquaculture Alliance. By understanding the nature of how our food is produced, and what systems are in place to ensure sustainable practices, your choice in the supermarket, or fishmonger, can help ensure that you support producers working towards more sustainable aquaculture systems.

 

Read more about some of the Projects that Blue North has been involved in – HERE.

 

References

FAO 2014: The State of World Fisheries and Aquaculture: Opportunities and challenges. Food and Agricultural Organization of the United Nations.

Naylor, R. et al. “Effect of aquaculture on world fish supplies.” Nature 405.6790 (2000): 1017-1024.

Olsen, R. & M. Hasan. “A limited supply of fishmeal: Impact on future increases in global aquaculture production.” Trends in Food Science & Technology 27.2 (2012): 120-128.

Romero, J. C. Feijoó & P. Navarrete. Antibiotics in aquaculture-use, abuse and alternatives. INTECH Open Access Publisher, 2012.

Tacon, A. & M. Metian. “Feed matters: satisfying the feed demand of aquaculture.” Reviews in Fisheries Science & Aquaculture 23.1 (2015): 1-10.

Waite, R. et al. 2014. “Improving Productivity and Environmental Performance of Aquaculture.” Working Paper, Installment 5 of  Creating a Sustainable Food Future. Washington, DC: World Resources Institute. Accessible at http://www.worldresourcesreport.org.