World Aquaculture March 2019

60 MARCH 2019 • WORLD AQUACULTURE • WWW.WA S.ORG percent, corresponding to less use of commercial feed. In addition, reducing stocking density reduced the number of post-larvae required, whose cost corresponds to approximately 35 percent of operating costs in conventional farming. On the other hand, the use of substrates can increase productivity inside ponds (Figs. 6 and 7), and this would constitute an extra investment for the new system, although they can be made at low cost if using recycled material. Organic Prawns The results obtained also show that rearing pellet-free prawns could be an alternative to produce organic prawns. The organic food market is growing quickly around the world, including in Brazil, which has registered a 30 percent increase in revenues between 2011 and 2016 to about US$ 714 million. Organic production of M. rosenbergii in Kerala, India has been reported (Salin and Nair 2008) but organic aquaculture is still incipient in Brazil. Macrobrachium prawns presents very favorable characteristics for organic production: 1) omnivorous habit, feeding well on benthic organisms; b) easy sexual maturation and reproduction, dispensing with use of hormones; c) need for low stocking density due to intolerance to crowding, favoring animal welfare and d) easy adaptation to integrated culture with fish. In addition, the environment created by substrates and PVC pipes inside the pond reduces stress and provides an environment very similar to the natural habitat of prawns. The improvement of these results through further experiments can generate a preliminary technology for organic prawn production that, besides increasing economic feasibility, could strongly improve the sustainability of freshwater prawn culture. More trials will be done to assess the economic and environmental sustainability of the system. Notes Fisheries Institute - Aquaculture Research Center - APTA - SAA Av. Virgilio Baggio, 85 - 13641-004 - Pirassununga - SP – Brazil Corresponding author email: hlamarques@gmail.com References Food and Agriculture Organization (FAO). 2018. Global Aquaculture Production 19502016. Available at: http://www. fao.org/fishery/statistics/global-aquaculture-production/query/en Accessed January 31, 2019. Hepher, B. 1989. Principles of fish nutrition. In: M. Shilo and S. Sarig (eds). Fish Culture in WarmWater Systems: Problems and Trends. CRC Press, Boca Raton, p. 121-142. New, M.B. 2002. Farming freshwater prawns: A manual for the culture of Macrobrachium rosenbergii . FAO Fisheries Technical Paper 428, 212 p. Rhodes, R.J. 2000. Economics and business management. In: M.B. New and W.C. Valenti, (eds). Freshwater Prawn Culture: The Farming of Macrobrachium rosenbergii . Blackwell Science, Oxford, p. 369-392. Romano, N. and V. Kumar. 2017. Vegetarian shrimp: pellet-free shrimp farming. World Aquaculture 48(4):36-39. Salin, K.R. and C.M. Nair. 2008. Rice-prawn ( Macrobrachium rosenbergii ) farmers changing to organic mode in paddy fields of Kuttanad, Kerala, India. In: World Aquaculture 2008, Busan, 19–23 May 2008, Book of Abstracts, World Aquaculture Society, Baton Rouge, p. 634. Tidwell, J.H., S.D. Coyle, C.D. Webster, J.D. Sedlacek, P.A. Weston, W.L. Knight, S.J. Hill Jr., L.R. D’Abramo, W.H. Daniels and M.J. Fuller. 1997. Relative prawn production and benthic macroinvertebrate densities in unfed, organically fertilized, and fed pond systems. Aquaculture 149:227-242. Tidwell, J.H., S.D. Coyle, A.V. Arnum, C. Weibel and L.R. D’Abramo. 2001. Use of artificial substrates to maximizing production of freshwater prawns in temperate climates. World Aquaculture 32(3):40-42, 60. Uddin, M.S., M.E. Azim, M.A. Wahab, and M.C.J. Verdegem. 2009. Effects of substrate addition and supplemental feeding on plankton composition and production in tilapia ( Oreochromis niloticus ) and freshwater prawn ( Macrobrachium rosenbergii ) polyculture. Aquaculture 297:99-105. FIGURE 6. Partially drained pond showing six lines of substrates. FIGURE 7. Another view of substrates and pond walls covered by periphyton. The improvement of these results through further experiments can generate a preliminary technology for organic prawn production that, besides increasing economic feasibility, could strongly improve the sustainability of freshwater prawn culture.