Global Food Security 23 (2019) 64–73 Contents lists available at ScienceDirect Global Food Security journal homepage: www.elsevier.com/locate/gfs Microencapsulated diets to improve bivalve shellfish aquaculture for global food security T ∗ David F. Willer , David C. Aldridge Department of Zoology, The David Attenborough Building, University of Cambridge, Pembroke Street, Cambridge, CB2 3QY, United Kingdom ARTICLE INFO ABSTRACT Keywords: There is a global need to sustainably increase aquaculture production to meet the needs of a growing population. Microencapsulated diet Bivalve shellfish aquaculture is highly attractive from a human nutrition, economic, environmental and eco- Bivalve shellfish system standpoint. However, bivalve industry growth is falling behind fish aquaculture due to critical problems Food security in the production process. Feed defects, disease, and quality issues are limiting production. New advances in Aquaculture microencapsulation technology have great potential to tackle these problems. Microencapsulated diets could Sustainable efficiently deliver high-quality nutrients, disease control agents, and quality enhancers to bivalves. Microencapsulation has the potential to drive improvements in bivalve production, reduce production costs, enhance human nutrition and minimise impacts on the environment. 1. The global importance of bivalve shellfish aquaculture fastest growing food sector (FAO, 2017; Jacquet et al., 2017; Tacon and Metian, 2013; Troell et al., 2014). However, like terrestrial meat pro- 1.1. Bivalves a strategic food source to sustainably feed a growing global duction aquaculture is currently expanding in an unsustainable way population (Godfray et al., 2010; Jacquet et al., 2017). Production quantity of carnivorous species such as salmon, catfish, and shrimp has ballooned, Over 800 million people worldwide are hungry, one billion have growing 84% over the last decade, and today salmon is the largest inadequate protein intake, and an even greater number suffer from single commodity in aquaculture (FAO, 2017, 2016). Production of nutrient deficiencies (FAO, 2015). By 2050 these and 2.5 billion addi- these species is reliant upon fish meal and fish oil from wild-caught fish, tional people will need access to nutritious food (“United Nations with 5 kg of wild-caught fish required to produce 1 kg of farmed salmon Population Division. World Population Prospects,” 2017). Consequently (Bostock et al., 2010). Wild fish stocks are suffering; 31% of stocks are by 2050 both total food demand and animal protein demand are ex- overfished and a further 60% fished to their biological limit (FAO, pected to double (Jennings et al., 2016). Terrestrial meat production 2016). Total capture of wild fish has been static since the 1980s despite has tripled over the last 40 years to keep pace with demand (Stoll- increased fishing effort (FAO, 2016). Kleemann and O'Riordan, 2015). But this growth is unsustainable; To sustainably provide food for a growing global population, there terrestrial meat production is a major driver behind humanity ex- is a great need for aquaculture to focus on species lower in the food web ceeding safe biophysical thresholds for the planet, and already uses that require little or no fish as feed (Jacquet et al., 2017)(Godfray et al., 70% of agricultural land and 30% of freshwater, and causes 18% of 2010). Bivalve molluscs offer one of the most attractive options for greenhouse gas emissions and 30% of biodiversity loss (Campbell et al., meeting this sustainability need. In 2015 14.8 million tonnes of bivalves 2017; Stoll-Kleemann and O'Riordan, 2015). Expanding aquaculture is were produced globally, and if bivalve aquaculture was to grow at the seen as a possible solution and has been identified as a critical com- same rate as predicted for carnivorous fish aquaculture over the next ponent in securing food for 9.8 billion people by 2050 (Godfray et al., decade, an extra 13.1 million tonnes of bivalves would be produced per 2010; Troell et al., 2014; Waite et al., 2014). year, feeding nearly twice as many people as bivalves do today (FAO, Globally over 3 billion people depend on aquaculture for at least 2017). 20% of their dietary protein (Troell et al., 2014). Over the last decade animal aquaculture production has grown at 5.6% per year to 78 mil- lion tonnes, was worth US$ 160 billion in 2015, and is the world's ∗ Corresponding author. E-mail address: [email protected] (D.F. Willer). https://doi.org/10.1016/j.gfs.2019.04.007 Received 2 May 2018; Received in revised form 14 April 2019; Accepted 15 April 2019 2211-9124/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/). D.F. Willer and D.C. Aldridge Global Food Security 23 (2019) 64–73 Fig. 1. The lower environmental footprint of bivalve aquaculture compared to other plant and meat food sources. Raw data for animal meats from (Waite et al., 2014). Freshwater consumption data for plant crops from (Mekonnen and Hoekstra, 2014) and converted from tonnes food to tonnes protein using (“USDA Food Composition Databases. United States Department of Agriculture Agricultural Research Service,” 2017). Greenhouse gas emissions, land use, and eutrophication potential data for plant crops from (Clark and Tilman, 2017). Note the broken axes due to high values for beef. 1.2. Nutritional, economic and environmental benefits of bivalve waters globally (Waite et al., 2014). Bivalve farming also provides a aquaculture wide array of marine ecosystem benefits, including the provision of nursery habitats for fish, filtration of the water column, enhanced de- Bivalve shellfish aquaculture is highly attractive from a human nitrification rates, coastal protection, buffering against harmful phyto- nutrition, economic, environmental and ecosystem standpoint and de- plankton blooms, and even restoration of coastal and estuary ecosys- serves a concerted research-led industry focus to increase production. tems (Gallardi, 2014; zu Ermgassen et al., 2013). Caution should of Bivalves have a higher protein content than beef (140 vs 85 mg protein course be taken when expanding bivalve aquaculture to avoid some of − kcal 1), and are a rich source of essential omega-3 fatty acids including the potentially deleterious environmental effects; species native to a docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), needed region are best selected for aquaculture to avoid ecosystem damage for infant development, cognitive function and cardiovascular and caused by the introduction of non-indigenous species, and the potential neural disease prevention (Adarme-Vega et al., 2012; Tacon and risks of increased sedimentation from bivalve excrement should be as- − Metian, 2013). DHA and EPA levels in bivalves (1.76 and 2.12 mg g 1 sessed case by case (Branch and Nina Steffani, 2004). With careful − respectively) are comparable with oily fish (2.61 and 2.27 mg g 1) and planning, a concerted effort to increase bivalve production could make − far exceed that of terrestrial meats (0.02 and 0.03 mg g 1)(Tacon and up an invaluable component of global goals to provide nutritious and Metian, 2013). Bivalves are highly affordable, with a global average sustainable food to people over the coming decades. − − farm gate price of $1.10 kg 1, compared to $4.70 kg 1 for salmon and − $2.10 kg 1 for aquaculture in general (Waite et al., 2014). The environmental footprint of bivalve aquaculture is also far lower 1.3. Global bivalve aquaculture production, management, distribution and than all other forms of meat or fish production and many arable crops, consumption in terms of greenhouse gas emissions, land use, freshwater use, and eutrophication potential per unit protein (Fig. 1). To help appreciate The bivalve shellfish sector is an important growing global industry. just how significant this is, if just 25% of carnivorous fish aquaculture Production quantity has grown at 2.7% per year over the last decade was replaced with an equivalent quantity of protein from bivalve and in 2015 14.8 million tonnes of the major bivalve species (oysters, shellfish aquaculture, 16.3 million tonnes of CO2 emssions could be clams, mussels and scallops) were produced with a farm gate value of saved annually, equivalent to half the annual emissions of New Zealand US$17 billion (Fig. 2)(FAO, 2017). Over 93% of bivalve production (Waite et al., 2014; “World Bank. CO2 Emissions,” 2017). An area of occurs in Asia, and over 90% of Asia's production is in China, with the land larger than Wales (2.7 million ha) could be spared from conversion remainder in coastal areas of Europe, the Americas, and Oceania to farmland, 11.8 billion litres of freshwater could be saved each year, (Fig. 2)(FAO, 2017). Production per capita varies significantly between and a net 21.1 million kg of P could be removed from eutrificated countries and is highest in New Zealand at 16.8 kg per capita (FAO, 2017; “World Bank. Total Population,” 2017). Historical farming 65 D.F. Willer and D.C. Aldridge Global Food Security 23 (2019) 64–73 Fig. 2. A synthesis of the global production of bivalves, highlighting the importance of Pacific and western European nations. The total quantity of bivalves produced in 2015 by country is shown on the cartogram in (a); the relative size and shading of countries is scaled according to production quantity (Andrieu et al., 2008). A breakdown of bivalve production quantity by species for the top 25 countries is shown on a logarithmic scale in (b), and the production quantity per capita for these countries in (c). The global growth in bivalve production quantity and value is displayed in (d) and (e) respectively. Raw data from (FAO, 2017; “World Bank. Total Population,” 2017). 66 D.F. Willer and D.C. Aldridge Global Food Security 23 (2019) 64–73 Fig. 3. Shandong: a major shellfish production centre in China.