Aquaculture is one of the fastest-growing food-producing sectors worldwide, making it desirable to assess the sustainability of aquaculture systems. The objective of this study was to develop a portfolio of quantitative indicators of economic, environmental and social sustainability to assess different aquaculture systems. The indicators were developed from 2003 to 2016, combining top-down and bottom-up methods, together with practical observations in experimental and commercial aquaculture facilities. A total of 56 economic (14), environmental (22) and social (20) indicators are proposed. Economic sustainability indicators reveal the degree of efficiency in using financial resources, the economic feasibility, resilience, and the capacity to absorb negative external costs and to generate funds for reinvestment. Environmental indicators reflect the use of natural resources, the efficiency in using resources, the release of pollutants and unused byproducts, and the risk of reducing biodiversity. Social sustainability indicators reflect the capacity to generate benefits for local communities, including jobs and food security, equitable income distribution, equality of opportunity, and inclusion of vulnerable populations. The indicators thus developed can be used on farm, regional, global or sectorial scales. They are quantitative, broad, scientifically sound, easy to understand and interpret, feasible to obtain on farms or on research stations, and permit comparison at different scales of space and time. Thus, they can be used to assess production systems and to compare different experimental treatments in research experiments. They also can be used by certifying organizations, investors, and policymakers. They allow performing diagnostics, identifying strengths and weaknesses, setting goals and determining actions, and assessing the effectiveness of actions and public policies.

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The effects of intensification on growth, survival, productivity, population structure, and distribution of harvested biomass in individual size classes of Macrobrachium amazonicum in semi‐intensive culture were evaluated. Postlarvae (0.01 g) were stocked in 12 ponds at densities of 10, 20, 40, and 80/m2 (three replicates per treatment) and raised for 5.5 mo. Average individual weight significantly decreased and productivity significantly increased as stocking density increased (P < 0.001), while survival was not affected (P > 0.05). Prawn mean weight at harvest ranged from 3.6 (80/m2) to 7.0 g (10/m2). Average survival ranged from 65.5% (40/m2) to 72.8% (20/m2), while productivity ranged from 508 (10/m2) to 2051 kg/ha (80/m2). Harvested biomass showed a clear bimodal distribution in individual size classes indicating the occurrence of heterogeneous growth, which may affect management and market strategies. Harvested biomass of prawns weighing more than 7 g (the best market size) increases for stocking densities up to 40/m2 and stabilizes between 40 and 80/m2. Growth reduction was associated with a decreasing frequency and average weight of green claw 1 and green claw 2 male morphotypes and adult females as density increased. Thus, the distribution of male morphotypes and sexually mature females are affected by density‐dependent factors. Results suggest that prawn density plays an important role on M. amazonicum grow‐out phase, as has been demonstrated for other species of the genus Macrobrachium. M. amazonicum tolerates grow‐out intensification and may be raised in both semi‐intensive and intensive systems stocked at very high densities yielding high productivity.

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The Amazon River prawn Macrobrachium amazonicum is widely distributed in lentic and lotic environments of South America, and shows different male morphotypes. In the present study, the effect of crowding on the general population structure of this species and its variation over time were evaluated. Prawns were reared in mesocosms consisting of 12 rectangular ~100 m 2 earthen ponds for ~160 d at densities of 10, 20, 40, and 80 prawns m -2 . Prawn density affected both individual and population development. Increased density reduced the size and frequency of the largest male morphotypes and reproductive females, delayed female maturation, and enhanced the asymmetry of the size distribution of individuals, increasing the frequency of smaller prawns. Although mortality was not affected up to 80 ind. m ). Therefore, the ontogeny and population development after metamorphosis are density-dependent processes. In conclusion, M. amazonicum has a dynamic and densitydependent population structure. This may be due to intrinsic regulatory mechanisms of the species and/or intraspecific competition. It seems that shifts in the sex ratio and the development pattern of male morphotypes are traits which evolved as part of the life strategy to decrease intraspecific competition in crowded conditions and to maintain a large population size. KEY WORDS: Intraspecific competition · Density-dependent factors · Sex ratio · Crustacean · Mesocosm · Macrobrachium amazonicum Resale or republication not permitted without written consent of the publisherAquat Biol 9: [291][292][293][294][295][296][297][298][299][300][301] 2010 ment plans for fisheries in order to guarantee longterm sustainability. M. amazonicum also has a high potential for aquaculture (Kutty 2005, New 2005. During the current decade, an intense research effort has been directed toward developing the technology for its commercial culture (Moraes-Valenti & Valenti 2010).Despite the high biological and economic importance of Macrobrachium amazonicum, its population biology is poorly understood. Natural populations inhabiting coastal areas show great variability in size, due to heterogeneous growth caused by the existence of 4 male morphotypes (Moraes- Riodades & Valenti 2004, Santos et al. 2006, da Silva et al. 2009). Some population studies have been performed in the eastern (KCA Silva et al. 2002a,b, 2005, MCN Silva et al. 2007) and central (Odinetz-Collart 1991a,b) Amazon basin. These studies suggest that reproduction, recruitment, and the size distribution of the prawn are site-dependent. However, the data presented did not cover other important ecological aspects, such as the population density, structure of the male morphotypes, mortality rates, reproductive capacity, intraspecific competition, and density-dependent processes. Therefore, more research is needed to fully understand the population biology of the Amazon River prawn.The aim of the present study was to evaluate the effect of density on population development of Macrobrachium amazonicum reare...

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