ANALYSIS - Aquaculture is at a crossroads. As a relatively new industry facing the pressure of driving higher rates of production per unit area, it has the opportunity to learn from the mistakes of others and embrace sustainable management practices, writes Øistein Thorsen from the sustainability advisory firm Trie.
Industry success will come from identifying and tackling material issues that reflect the sector’s most significant economic, ethical and environmental impacts and opportunities.
According to the United Nation’s Food and Agriculture Organization (FAO), the last three decades have seen global food fish aquaculture production expand “by almost 12 times, at an average annual rate of 8.8 per cent.” Sustainability is already at the heart of aquaculture’s market appeal. It provides seafood to an ever-growing market without depleting the world’s wild fish stocks.
Furthermore, with its effective feed to protein conversion rates, aquaculture’s main appeal is its potential to help feed the growing global population in an era of extreme land, fresh water and nutrient constraints. This young industry’s long-term success and economic viability depends on harnessing these traits and investing in innovation and solutions aimed at tackling the triple sustainability challenge of disease, waste and feed in parallel with its current explosive global expansion.
Be Good Stewards
The artificial ecosystems that aquaculture creates, pose many challenges that can be tackled through best stewardship practices. Such practices aim to accommodate the natural behaviors and environment of the farmed species in the design of farming practices, facilities and technology. By facilitating humane fish treatment innovations in equipment and practice, it can mitigate disease pressures. In this regard fish welfare is not simply an altruistic agenda, but rather the backbone of a healthy business. Dr Pete Southgate of the Fish Vet Group, a company dedicated to improving total aquaculture health, argues that humane practices have been shown to produce better fish growth, more efficient food conversion, increased resistance to disease, and overall increase in organism survival.
To ensure productive and profitable farming methods prevention of disease, rather than just relying on treatment of diseases, will need to be developed and perfected. Over-reliance on antimicrobials and other pharmaceutical disease treatments, rather than investing in prevention through best practices, will perpetuate the development of new diseases and resistance. Good stewardship, adapted to different farming methods and environments, promote stable ecosystems, reduce risk of disease outbreaks and facilitate greater economic longevity. The success of this approach also relies on continued investment in people. Providing appropriate training, support and protection to the work force is a crucial pillar of ensuring prosperous industry based on good stewardship.
“It only becomes waste if it’s wasted”
For many years it was assumed the size of the ocean and the power of its currents would dilute any waste introduced, to the extent that it would not be noticeable. However, experience in certain intensive fish farming environments has shown that waste plumes can become significant pollutants and the cause of conflict between fish farmers and their coastal neighbors.
Waste management requires comprehensive case-by-case planning due to the diversity of the industry and diversity of waste from different species and systems. In a review of 12 aquaculture Life Cycle Analyses (LCAs) published in the magazine BioScience “comparisons showed that closed (recirculation or zero-discharge) systems out- performed flow-through systems in eutrophication emissions and biodiversity conservation but not in energy use and greenhouse gas emissions (Cao et al. 2013).” In other words, no one system in existence outperforms all others in all waste emission categories, showing the need for continued innovation in this field.
In one exploration of alternative aquaculture technologies the researchers warned that with the systems we have available today we might be faced with a tradeoff between reducing local environmental impacts and increasing material and energy demands, contributing to global warming, nonrenewable resource depletion, and acidification.
One opportunity ripe for further exploration is the design of systems that use waste as nutrition and fuel for secondary crops or products. Finfish waste can fuel the production of other species, like shellfish, or plants, like seaweeds and vegetables, in carefully designed multitrophic or aquaponics systems. In conventional systems where waste can be collected there is unexplored potential for it to be converted into feed, fertilizer or energy at an industrial scale. These opportunities can reduce on-farm cost by reducing feed and electricity bills, reduce emissions of pollutants like greenhouse gasses, and provide additional income streams by turning waste into sought after products like biogas, fertilizer or even carbon credits.
Feed for the Future
For most conventional aquaculture operations, feed is generally the most costly input, and a rising one. The changing practices brought on by rapid commercialization have pushed producers towards higher stocking densities that require higher feed input. This represents a complex challenge for the industry both in terms of ensuring sustainable feed management and feed sourcing.
Overfeeding and egestion is the main source of waste materials in many large aquaculture practices, contributing to deteriorating local water quality. In response to this problem, new technology that monitors food waste and effectively regulates food delivery has been developed. This has successfully reduced food waste dramatically from 20 per cent in 1989 to just about three per cent today in many systems. This is just one example of where technological innovations coupled with good stewardship practices are driving industry sustainability.
With regards to feed sourcing, such a quick fix has not been identified, though there are signs of continuous progress. Currently, there are two dominant feed-source options for large-scale aquaculture farmers, plant-based feed and fishmeal-based feed, which in most systems are used in combination.
Reliance on these two feed types poses long-term risks to aquaculture’s economic viability and consumer appeal. Fishmeal and fish oil derived from wild-caught smaller forage fish like anchovy to feed carnivorous fish like, salmon, perpetuates the depletion of wild fish stocks. This in-turn undermines one of the key strengths of aquaculture.
The World Wildlife Fund (WWF) claims one third of the world’s fish catch was used to produce fishmeal and fish oil in 2004, most of which was used by the aquaculture industry. The good news is that market trends show the reliance on fishmeal and fish oil is rapidly decreasing at annual average rates of 1.7 and 2.6 per cent, respectively. This decline is fueled by increased production of plant-based feed from major agricultural crops like soybean and corn.
With rising and volatile commodity prices fueled by pressures on agricultural land use and changing climate, reliance on such crops can also prove risky and expensive long-term for fish farmers. While a plant based diets are ideal for species like tilapia and carp, the pathological impact of feeding carnivorous fish alternative raw materials, such as the development of intestinal malabsorption and inflammation, cannot be ignored.
Researchers worldwide are, therefore, intensifying their research into opportunities for using bacteria, yeast, algae, insects and animal by-products as feed ingredients. Recent technological developments at Norway’s Aquaculture Protein Centre (APC) have for example made it possible to “utilize yeast to convert wood chips into a high-value protein source.” They have also found positive health benefits for farmed fish fed on yeast and bacteria grown on natural gas. By-and-large these initiatives are in their early stages and not yet ready for industrial application, however, they should be encouraged and invested in as they hold the key to aquacultures’ sustainability in a resource constrained world.
An Industry to be Proud Of
Aquaculture is in a continuous state of change. New technologies, new farm techniques, genetic selection, alternative feed compositions and innovative approaches to water and waste management are being developed by farmers and practitioners around the world. With the industry going global, intensification is the driving force and farmers break boundaries for what is possible every day.
Trie proposes that a guiding principle in the sector’s race to do more with less should be aquaculture’s innate sustainable appeal. This is an industry for the future that holds the promise to feed our world’s growing global population without depleting our limited resources. Let’s work together to make tomorrow’s aquaculture a replicable sustainable industrial food production model we can all be proud of.