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Aquatic food is recognized to be beneficial to human nutrition and health and will play an essential role in future sustainable healthy diets (Beveridge et al. 2013). In order to achieve this, the global aquaculture sector must contribute to increasing the quantity and quality of fish supplies between now and 2030 (Thilsted et al. 2016). This growth should be promoted not only by increasing the production and/or number of species but also by systems diversification. However, fish from aquaculture has only recently been included in the food security and nutrition (FSN) debate and the future strategies and policies, demonstrating the important role of this production to prevent malnutrition in the future (Bénét et al. 2015), as fish provide a good source of protein and unsaturated fats, as well as minerals and vitamins. It is important to note that many African nations are promoting aquaculture as the answer to some of their current and future food production challenges. Even in Europe, fish supply is currently not self-sufficient (with an unbalanced domestic supply/demand), being increasingly dependent on imports. Therefore, ensuring the successful and sustainable development of global aquaculture is an imperative agenda for the global and European economy (Kobayashi et al. 2015). Sustainability is generally required to show three key aspects: environmental acceptability, social equitability and economic viability. Aquaponic systems provide an opportunity to be sustainable, by combining both animal and plant production systems in a cost-efficient, environmentally friendly and socially beneficial ways. For Staples and Funge-Smith (2009), sustainable development is the balance between ecological well-being and human well-being, and in the case of aquaculture, an ecosystem approach has been only recently understood as a priority area for research.
Aquaculture has been the fastest growing food production sector during the last 40 years (Tveterås et al. 2012), being one of the most promising farming activities to meet near-future world food needs (Kobayashi et al. 2015). Total production statistics from aquaculture (FAO 2015) reveal an annual increment in global production of 6%, which is expected to provide up to 63% of global fish consumption by 2030 (FAO 2014), for an estimated population of nine billion people in 2050. In the case of Europe, the predicted increase is seen not only within the marine sector but also in terrestrially produced products. Some of the expected challenges to the growth of aquaculture during the coming years are the reduction in the use of antibiotics and other pathological treatments, the development of efficient aquaculture systems and equipment, together with species diversification and increased sustainability in the
area of feed production and feed use. The shift from fishmeal (FM) in feed to other protein sources is also an important challenge, as well as the 'fish-in-fish-out' ratios. There is a long history, reaching back to the 1960s, of promoting the growth of the aquaculture sector towards proper sustainability including the encouragement to adapt and create new and more sustainable feed formulas, reduce feed spilling and reduce the food conversion ratio (FCR). Although aquaculture is recognized as the most efficient animal production sector, when compared with terrestrial animal production, there is still room for improvement in terms of resource efficiency, diversification of species or methods of production, and moreover a clear need for an ecosystem approach taking full advantage of the biological potential of the organisms and providing adequate consideration of environmental and societal factors (Kaushik 2017). This growth in aquaculture production will need to be supported by an increase in the expected total feed production. Approximately three million additional tons of feed will need to be produced each year to support the expected aquaculture growth by 2030. Moreover, replacing fishmeal and fish oil (FO) with plant and terrestrial substitutes is needed which requires essential research into formula feed for animal farming.
The animal and aquafeed industries are part of a global production sector, which is also the focus for future development strategies. Alltech's yearly survey (Alltech 2017) reveals that total animal feed production broke through 1 billion metric tons, with a 3.7% increase in production from 2015 despite a 7% decrease in the number of feed mills. China and the USA dominated production in 2016, accounting for 35% of the world's total feed production. The survey indicates that the top 10 producing countries have more than half of the world's feed mills (56%) and account for 60% of total feed production. This concentration in production means that many of the key ingredients traditionally used in formulations for commercial aquaculture feeds are internationally traded commodities, which subjects aquafeed production to any global market volatility. Fishmeal for example is expected to double in price by 2030, whilst fish oil is likely to increase by over 70% (Msangi et al. 2013). This illustrates the importance of reducing the amount of these ingredients in fish feed whilst increasing the interest and focus on new or alternative sources (García-Romero et al. 2014a, b; Robaina et al. 1998, 1999; Terova et al. 2013; Torrecillas et al. 2017).
Whilst new offshore platforms have been developed for aquaculture production, there is also a significant focus on marine and freshwater recirculating aquaculture systems (RAS), as these systems use less water per kg fish feed used, which increases fish production whilst reducing environmental impacts of aquaculture including reductions in water usage (Ebeling and Timmons 2012; Kingler and Naylor 2012). RAS can be integrated with plant production in aquaponic systems, which readily fit into local and regional food system models (see Chap. 15) that can be practised in or near large population centres (Love et al. 2015a). Water, energy and fish feed are the three largest physical inputs for aquaponic systems (Love et al. 2014, 2015b). Approximately 5% of feed is not consumed by the farmed fish, whilst the remaining 95% is ingested and digested (Khakyzadeh et al. 2015). Of this share, 30—40% is retained and converted into new biomass, whilst the
Aquaponic Feed Development and the Circular Bioeconomy
Fig. 13.1 Schematic representation of a multidisciplinary approach to locally valorize bio-byproducts for aquaponic diets. (Based on 'R+D+I towards aquaponic development in the ultraperipheric islands and the circular economy'; ISLANDAP project, Interreg MAC/1.1a/2072014-2019)
remaining 60—70% is released in the form of faeces, urine and ammonia (FAO 2014). On average, 1 kg of feed (30% crude protein) globally releases about 27.6 g of N, and 1 kg of fish biomass releases about 577 g of BOD (biological oxygen demand), 90.4 g of N and 10.5 g of P (Tyson et al. 2011).
Aquaponics is currently a small but rapidly growing sector which is clearly suited to take advantage of the following political and socio-economic challenges, where 1) aquatic produce meets the need for food security and nutrition, 2) fish self-sufficient regions are established around the world, 3) aquaculture is a key sector but global ingredients and global feed production comes under focus, 4) innovation in agriculture promotes biodiversity in more sustainable ways and as part of the circular economy and 5) there is a greater take up of locally produced foods. These aspects tie in with the recommendations from the International Union for the Conservation of Nature (Le Gouvello et al. 2017), regarded the sustainability of the aquaculture and fish feed, which has recommended that efforts should be made to localize aquaculture production and the circular approach, and for putting in place a quality control programme for new products and by-products, as well as processing local fish feed within regions. So far, aquaponics as 'small-scale aquaculture farms' could provide examples for the implementation of the bioeconomy and local-scale production, thus promoting ways of using products and by-products from organic matter not suitable for use for other purposes, e.g. farmed insects and worms, macroand microalgae, fish and by-product hydrolysates, new agro-ecology-produced plants and locally produced bioactives and micronutrients, whilst reducing the environmental footprint with quality food (fish and plants) production and moving towards zero waste generation. Moreover, aquaponics provides a good example for promoting a multidisciplinary way of learning about sustainable production and bioresource valorization, e.g. the 'Islandap Project' (INTERREG V-A MAC 20142020) (Fig. 13.1).
The following sections of this chapter review the state of the art of fish diets, ingredients and additives, as well as nutritional/sustainable challenges to consider when producing specific aquaponic feeds.