The SEAT project is aiming for major gains in fish and shellfish farming, says Dave Little.

Dave Little

Feeding people requires a lot of energy. Production, distribution and consumption of food accounts for 20-25% of the energy consumption in developed countries. The largest energy investments are made in the production of protein-rich produce, such as meat and fish. In beef production, for example, energy used (per kilo of whole animal produced) ranges from 38-48 MJ/kg-1 compared to meat derived from pigs at 16-18MJ/kg-1.  

Fishing at sea requires much less energy than beef production. All the same, energy intensities in capture fisheries have increased six-fold in the last two decades to an average of 24 MJ/kg-1 of fish landed. This increase in energy intensity is due to longer distances travelled to reach productive fishing grounds and greater efforts needed to catch the same amount of fish as in previous years.

So can farmed freshwater fish offer a less energy intensive form of animal production? As John Forster has also argued on this blog, aquaculture has a potential increased efficiency compared to other forms of animal production. This comes from the ability for nutrients to be recycled and turn waste flows into feed resources, lowering the energetic costs associated with growing, creating and transporting feed products.

Aquaculture therefore can produce a greater amount of animal product for the same energy inputs than other forms of animal-sourced food. It is also worth noting that as well as providing a good source of protein, many types of seafood bring a whole range of nutrients to the diet including omega-3 fatty acids not found in other animal-derived food stuffs.

Net gain

Despite the long history of fish farming, many aquaculture systems are still emerging. Realizing the optimum efficiency of animal production depends on how the industry develops. Current estimates of energy used in food systems show that aquaculture products, for example Pangasius (often sold as ‘river cobbler’, 17-20 MJ/kg-1) and Tilapia (18-27 MJ/kg-1), can approach the energy efficiency, per kilo of animal produced, as broiler chickens (12 MJ/kg-1), one of the cheapest forms of animal protein.

However, the rapid growth of the industry means action must be taken to ensure that it remains sustainable and that energy input compared to output is kept low. If this is achieved, aquaculture could provide one of the most sustainable forms of animal protein production. Many aquaculture systems are already examples of this, such as salmon and tilapia.

Estimating the average energy input for individual fish species produced from aquaculture is difficult due to the range of farming practices, geographical and climatic conditions under which they are cultured. However when producing crustaceans and cultured fish such as tilapia, the majority of energy is used to produce feed. Processing may only account for 10% of energy used for many farmed seafood products while consumption typically contributes about 20-30% of total energy required. As the industry continues to grow, production methods in emerging species will become standardized.

Scale up

How these systems are intensified will be key. Using plant-based feeds can reduce energy input into feed ingredients for herbivorous fish such as tilapia or to supplement fishmeal as is occurring in salmon. Some fishmeal will always be required however and specialized industrial monocultures may become net producers of fishmeal (by utilizing by-products) reducing pressure on capture fisheries. Lowering energy inputs, in feed-production for example, makes the system more environmentally sustainable, and less vulnerable to fluctuations in local and global energy prices.

Rapid economic growth in emerging economies is leading to increased demand for animal protein, driving up food prices. Meeting this demand should favour energetically cheap systems within aquaculture, focusing on omnivorous or lower trophic level culture species. Filter feeding fish and shellfish such as mussels, that primarily grow on plankton and rely on little/no inclusion of fish- or livestock-derived materials are proven approaches to reducing environmental impacts and enhancing food security. Learning from the innovations of the producers themselves and combining this knowledge with that of scientists and business is likely to produce the highest gains.

If aquaculture is to be part of the solution and provide affordable, accessible food products, it needs to be developed in a sustainable way, which may mean reducing risks through the use of polycultures and considering reuse of byproducts from production and processing locally. Aquaculture enterprises as recycling hubs are emerging as an exciting opportunity in many diverse contexts. These may range from the local reuse of culture water as an irrigation source for horticulture to the manufacture of leather from fish skins, or products such as gelatine and chitosan from processing wastes.

Considering aquaculture from a value chain perspective is critical to assessing energy efficiency and its overall societal impact. Building greater sustainability into aquaculture needs to consider species trophic level, but increasingly will require nutritional and management innovation. These factors are often overlooked in favour of a focus on genetic improvement and health management strategies, which are themselves generally undeveloped compared to terrestrial livestock. Business and policy actors need to have a broader viewpoint for ensuring food security of aquatic products that transcends narrow production systems and embraces broader measures of efficiency and productivity

On the Sustaining Ethical Aquaculture Trade (SEAT) project, we are working to ensure that aquaculture continues its path to becoming an ethical and sustainable industry which can help feed the world.

Add your comment

About Dave Little

Professor David Little of the Sustainable Aquaculture Group at the Institute of Aquaculture, University of Stirling, has experience in tropical aquaculture with a strong background in hatchery development. His interest in aquaculture research for development has embraced both technical initiatives and broader interdisciplinary programs.

Dr Little coordinates the EU-funded project Sustaining Ethical Aquaculture Trade (SEAT, FP7) that aims to enhance the sustainability of production and trade in Asian farmed seafood with Europe. He is editor of the Sustainability and Society section of the journal Aquaculture, a Board Director of the World Aquaculture Society and Aquaculture without Frontiers, and on the Standards Oversight Committee for the Global Aquaculture Alliance.

You may also be interested in: