Dr. David C. Love, Johns Hopkins University, United States & Dr. Kanae Tokunaga, The University of Tokyo, Japan

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1 Dr. David C. Love, Johns Hopkins University, United States & Dr. Kanae Tokunaga, The University of Tokyo, Japan Aquaponics fish tank, Hawaii Department of Agriculture Source: USDA By 2050, demands for water and food are expected to increase 55% and 60%, respectively 1. Billions of humans rely on seafood as a food source, and half of edible seafood comes from aquaculture, the practice of farming aquatic organisms. Nearly two thirds of aquaculture occurs inland, which requires access to surface water and groundwater 2. Access to water is becoming more limited and variable in some regions due to climate change and competition by various users. In the United States (US), for example, aquaculture operations withdrew 8.8 billion gallons per day in 2005, which was four times more than what is used for livestock 3. These estimates do not account for water used to raise crops incorporated in aquaculture feeds, which could double the water use estimates. In the coming decades, aquaculture must find ways to use water more efficiently as the industry expands to meet global demand. One water-saving technique for raising food fish is called recirculating aquaculture, where water is cycled between fish-rearing tanks and waste treatment tanks using a small amount of recharge water each day. Aquaponics is a type of recirculating aquaculture where edible plants are used to remove soluble fish waste in tandem with physical and biological (microbial) waste treatment. Research questions and methods We used case studies and surveys to investigate two research questions related to Global Water Forum 1

2 aquaponics: What is the nature of resource use (water, energy, feed, labor) in small-scale commercial aquaponics? What are the economic inputs and outputs of these small-scale commercial aquaponics? As case studies, we selected five commercial aquaponic farms in Hawaii, US 4 and one smallscale aquaponics research and teaching facility in Maryland, US 5. In Hawaii, we conducted an extensive survey of the three commercial aquaponic farms and, based on the information collected, constructed a representative case to analyze economic feasibility of commercial aquaponics. The Hawaii and Maryland case studies were conducted independently by different research groups, which explains why some measurements were taken in one study but not the other. In addition to case studies, we conducted a large online survey in 2013 to collect baseline information on commercial aquaponics which is described in Love et al. (2014) 6. Over 250 respondents from 23 countries completed the survey and met the inclusion criteria for being a commercial operation. Results Production information in Hawaii and Maryland The representative system derived from the surveyed operations in Hawaii has a total surface area of 1,142 square meters of raft troughs, contains 75.7 cubic meters of fish tanks, and produces 16,248 kg of lettuce and 1,905 kg of tilapia (common aquaculture fish) annually. The ratio between fish tank volume and vegetable grow bed surface area is litres per square meter, which was calculated based on information provided by the farms and biological considerations. The actual system in Maryland has a total of 26.8 square Global Water Forum 2

3 meters of raft troughs, contains 3 cubic meters of fish tanks, and generates 358 kg of produce and 123 kg of tilapia annually. Resource use Water use and water efficiency vary among the farms we studied and are reported in Table 1. In our analysis of the Hawaii case model, we assumed that 5.1 cubic meters of water are added, without accounting for rainwater, annually to the system. Typical farms on the Island of Oahu can expect about 150 cm of rainfall annually. The operation in Maryland recharges 1% of its water daily, which comes to 36 cubic meters annually. Rainwater is not added to the Maryland operation. Some of the farms studied in Hawaii have enough precipitation to compensate for water losses; however, 100% rain-fed systems are rare for most other US commercial operations. Among US commercial aquaponics operations, roughly a third of operations use exclusively municipal water, one fifth use exclusively groundwater or well water, and a third combine reliable sources such as municipal water or groundwater with intermittent sources such as rainwater or surface water. Comparing water efficiency per ton of food, the Hawaii model system uses 0.31 m 3 /ton lettuce and 2.7 m 3 /ton tilapiamuch less water than is required in Maryland using a non-rain fed system. Other factors related to resource use are also reported in Table 1. One notable difference was the energy use between Hawaii and Maryland. The difference can be attributed to a much larger overall operation in Hawaii, the use of electricity for refrigeration in Hawaii but not Maryland, and the lower heating demand in Hawaii compared to Maryland due to a warmer climate. In Maryland, propane powered greenhouse heaters are an expensive, and perhaps inefficient, way to heat the system compared to in-tank electrical water heaters. Other, more sustainable options for heating include solar thermal hot water heaters and high efficiency boilers or wood burning stoves connected to heat exchangers. Global Water Forum 3

4 In Hawaii, initial investment costs and annual operational costs are calculated as $217,078 and $66,183respectively. The system earns $98,012 of sales income, of which 79% derives from lettuce sales. The modified internal rate of return (MIRR) with 6% refinancing and reinvestment rate for the 30 years of operation Table 1: Resource use by aquaponics systems is 7.36%. With organic certification, the MIRR is in Hawaii and Maryland estimated to increase to 12-13%. Aquaponics and hydroponics both use nutrient rich water to raise crops. Aquaponic nutrients come from fish waste, while hydroponics uses fertilizers and mined minerals as nutrients. While further analysis is needed, our study in Hawaii suggests that aquaponics is more profitable because there are two profit centers (fish and crop) compared to hydroponics where there is a single profit center (crops). In addition, our interviews and analysis indicate that revenue made from plant production in aquaponics is subsidizing fish production. In Maryland, detailed economic analyses were not performed; however, we did calculate the energy costs per kg of product and determined that it is cost effective to generate produce but not cost effective to raise tilapia due to high winter heating costs and small fish harvests. This finding means that if the system were constructed purely for hydroponics (assuming hydroponic fertilizer inputs cost similar to aquaponics feed inputs) it would be more profitable than as an aquaponics system. Profitability was an important theme in the international survey, with just 31% of farms reporting that they were profitable in the previous 12 months. The point at which most respondents typically reported profitability was > $50,000 US dollars per year in gross sales revenue. We also report labor, investments, and sales outlets in the report 5. Additional Global Water Forum 4

5 factors related to profitability were farmer knowledge, whether the farmer s primary source of income was an aquaponics job, sales revenue, and climate. Future recommendations In order to fully understand how aquaponics compares to stand-alone aquaculture, hydroponic systems, or row crop production, more comprehensive studies, such as life cycle assessments, are needed. In one such study, Mekonnen and Hoekstra (2010) 6 identify the global average water use for vegetable production as 237 m 3 per ton (using blue + green water), which is significantly more than the model aquaponics system in Hawaii (just 0.31 m 3 per ton of lettuce). The water efficiency in Hawaii seems most likely due to rainwater capture, because the Maryland aquaponics system was not rain-fed and used 100 m 3 per ton of lettuce, which is of the same order of magnitude as estimates from Mekonnen and Hoekstra (2010). Because aquaponics does not require soil, it may be suitable for regions that lack arable land. Low- and middle-income countries that lack agricultural resources such as soil and fresh water could benefit from farming approaches that meet consumers demands for fresh vegetables and animal protein in their absence. Aquaponics, or other such forms of agriculture, could be implemented to improve food security; however, if aquaponics is selected then appropriate technology may need to be developed for low-resource settings, such as places with intermittent or no electricity or no access to plastic parts commonly used in Western aquaponics systems. An extension project in American Samoa found an aquaponics system to be well-suited for Pacific islands, where most of the food is imported due to limited land and population growth 8. In general, if start-up costs are high and maintenance costs from inputs are not controlled, aquaponics may not be a viable commercial option. We advise interested parties to consult existing farms in your region as well as local agriculture extension officers before developing new business ventures. Global Water Forum 5

6 References WWAP (United Nations World Water Assessment Programme) The United Nations World Water Development Report 2015: Water for a Sustainable World. Paris, UNESCO FAO State of the World Fisheries and Aquaculture United Nations. Rome. Available Online: Kenny, J.F., Barber, N.L., Hutson, S.S., Linsey, K.S., Lovelace, J.K., Maupin, M.A Estimated use of water in the United States in US Geological Service. Circular Reston, VA Tokunaga, K., Tamaru, C., Ako, H., Leung, P.-S., Economics of Small-scale Commercial Aquaponics in Hawaii. Journal of the World Aquaculture Society. 46(1):20-32 Love, D.C., Fry, J.P., Li, X., Hill, E.S., Genello, L., Semmens, K., Thompson, R.E Commercial aquaponics production and profitability: findings from an international survey. Aquaculture 435:67-74 Love, D.C., Uhl, M., Genello, L., A Production Model for a Small-Scale Aquaponics System in Baltimore, Maryland, United States. Journal of Aquacultural Engineering 68:19-27 Mekonnen, M.M. and Hoekstra, A.Y The green, blue and grey water footprint of crops and derived crop products. UNESCO-IHE. Value of Water. Research Report Series No 47. Availalbe online: Sakamoto, K., and Ako, H., Adapting Aquaponics for the Pacific Island: American Samoa. Presented at CTAHR/Hawaii Aquaculture & Aquaponics Association Workshop. Available online: Dr David C. Love is an Associate Scientist at the Center for a Livable Future, Bloomberg School of Public Health, Johns Hopkins University, Maryland, United States and Dr Kanae Tokunaga is currently a researcher at Ocean Alliance, The University of Tokyo, Tokyo, Japan. Global Water Forum 6

7 The views expressed in this article belong to the individual authors and do not represent the views of the Global Water Forum, the UNESCO Chair in Water Economics and Transboundary Water Governance, UNESCO, the Australian National University, or any of the institutions to which the authors are associated. Please see the Global Water Forum terms and conditions here. Global Water Forum 7