MONITORING THE IMPACT ON POND PRODUCTIVITY FROM LEARNING AT THE COASTAL FIELD SCHOOL 2016-2019

The monitoring of aquaculture farmers by the UNDIP/WUR-team aims to assess the progress towards reaching the goals set by the project Building with Nature – Demak. As planned in this first year the sample was taken in one village: Tambakbulusan. As farmers implemented the learning from the Coastal Field Schools during the same season as the training was given, no baseline for this sample was measured. In the village six ponds were monitored during one cropping season; we report on five ponds as one of the ponds was the demonstration pond on which Blue Forest will report. Before stocking the ponds were dried for at least 5 days and composted goat manure was mixed to the sediment. Thereafter an good dosage of home-made organic fertilizer was added to improve water quality; during the culture period a smaller dose was added weekly to maintain the plankton growth in the pond. The farmers prepared the organic fertilizer (compost), called MOL, from fermented rotten fruits, vegetables and household waste. One farmer used an industrial compost and another fed manufactured pellets; thus the five farmers implemented partly the promoted LEISA technology. Several of the cropping cycles couldn’t be completed due to heavy rains or flooding. The ponds were restocked. Some ponds were harvested early to avoid risk of mortality due to increase of salinity of shrimp showing disease symptoms. Other water quality parameters were within the limits for recommended limits for shrimp culture. For one production cycle only from five ponds in one village, the shrimp produced per ha was three times higher for the three LEISA farmers and for the other two 20 times higher than the average found in the Demak baseline for one full year, The average gross margin (income) was IDR 46 million/cycle, i.e. 4.5 times higher, but for the three LEISA farmers this was IDR 14 million/cycle, i.e. 40% higher than the average found in the Demak baseline for one full year. From the limited sample we conclude preliminary that the technology trained by the CFS allows to reach the goals set by BwN regarding pond productivity and income from aquaculture

Agriculture Diversification in the Mekong Delta: Farmers' Motives and Contributions to Livelihoods

Although specialization is the global trend in agriculture, integrated farming systems have emerged in Vietnam. An important motive was the desire to improve the livelihoods and the diet of the nuclear families; this was evident in the analysis using the household life cycle of five phases. Off-farm diversification was especially important for a new household. At the onset of expansion, the new mothers replaced off-farm with homebound activities. During expansion the farmers increased virtual farm size by keeping more livestock; during accumulation, they invested in land or education, and during consolidation old couples adjusted farm activities to their labor capacity. Livestock, including fish, was essential for livelihood. The distribution of goats instead of cattle by credit or by "passing-on-the-gift " was far more effective for poverty alleviation. Technological innovations on the cultivation of rice and fruits, and the breeding of fish were essential for change. The improved food security and reduced cash income from rice after the 1986 reforms pushed farmers to take risks. The farm area and number of component farm activities providing cash determined the level of cash income from agriculture. Farms with at least four flows of biomass between components earned more, demonstrating that real integration improved profits. A minimum area of land in, or close to, the homestead, and know-how are required for an effective integration of components.Mekong Delta, agricultural diversification

Organic matter reduction using four densities of seaweed (Gracilaria verucosa) and green mussel (Perna viridis) to improve water quality for aquaculture in Java, Indonesia

The high organic waste content of river water in Demak, north coast of Java, has caused traditional small-scale pond farmers to stop stocking shrimp. This paper examines whether seaweed and mussel will improve the quality of water these farmers use. The effect of Gracilaria verucosa and Perna viridis on the water quality was assessed by measuring the removal rates (RRs) of total organic material (TOM), total ammonia nitrogen (TAN), nitrite, and nitrate. The specific growth rates (SGRs) of seaweed and mussel were also measured. Thirty-six semi-outdoor tanks containing 800 L of brackish water and 7 cm substrate were randomly assigned to four replications of four densities of G. verucosa: 50 (S50), 100 (S100), 150 (S150), and 200 (S200) g m−2, and of P. viridis: 60 (M60), 90 (M90), 120 (M120), and 150 (M150) g m−2. Weekly, the TOM, TAN, nitrite, and nitrate contents were measured, seaweed and mussel weighted; RRs and SGRs were calculated at the end of the study. The effect of densities on the RRs was significant for both seaweed and mussel. P. viridis was more effective in reducing TOM (by 38%) than G. verucosa (7%); G. verucosa achieved higher RRs for TAN, nitrite, and nitrate. At S200, TOM and TAN decreased by 7.4% and 67%, respectively. At M90, TOM and TAN, decreased by 38% and 49%, respectively. However, nitrite increased significantly at S200 and M150. The SGR of seaweed was significantly lower at S200 than that at S150, S100, and S50. The best performing densities were S100 and M90

Comparing profits from shrimp aquaculture with and without green-water technology in the Philippines

To reduce disease impact, Philippine farmers developed the green-water (GW) system, which has been spreading rapidly since 2008. In the most applied GW-system, the shrimp pond receives water from a reservoir stocked with tilapia. We collected financial data on GW and non-GW systems from farms having similar management and environmental context. All farms had more than one pond; the average pond area was < 1 ha, and total pond areas per farm ranged from 1.4 to 139 ha. The total variable and fixed costs per ha of shrimp pond were not different for GW and non-GW farms, but on GW farms the cost per kg of shrimp produced was lower. The latter was higher than the 2009 market price of 30 g shrimp for non-GW farms mainly. In GW farms the cost of seed was lower, and survival rates and individual shrimp weights at harvest were higher for an equally long culture period.Preparation of this article was supported by the EC INCO-DEV MANGROVE project, which received research funding from the European Community’s Sixth Framework Programme (Contract: INCO-CT-2005-003697), and from the RESCOPAR project funded by Wageningen University

The Effect of Different Feed and Stocking Densities on Growth And Survival Rate Of Blue Swimming Crablets (Portunus pelagicus)

Blue swimming crab is targeted by commercial fisheries because of the high economic value, good taste, and attractive colors. As a result, the stock is overexploited and fisherman catch market also juveniles. The most sustainable solution would be to stop fishing for commercial trade and to culture this crab from brood to market size. This study aimed to find the best feed and stocking density for the on-growing of crablets. In 20 tanks juvenile crabs with a carapace width +1 cm were stocked in three densities; 40, 60 and 80 crablets /m2, and fed ad-libitum twice a day with either trash fish or pellets of shrimp feed, for 8 weeks. The circular (ᴓ 1.6 m x 1 m) tanks with 1 m3 of water were aerated, and temperature, salinity, dissolved oxygen and pH recorded daily. In the end, growth and survival rates were determined. In general, feeding the crablets at a density of 40 m-2 gave the highest growth. For crablest fed with pellets, the density of 40 m-2 gave significantly better growth than 80 m-2. The crablets at a density 40 m-2 having a fish diet with the density 40 m-2 grew better than 60 and 80 m-2. There was no significant difference between fed used among different densities. The lower densities resulted in higher survival, either on crablets fed with pellets or fish. But, crablets fed the fish diet and cultured in the lowest density (40 m-2) had the highest survival rate

Financial feasibility of green-water shrimp farming associated with mangrove compared to extensive shrimp culture in the Mahakam Delta, Indonesia

Paper presented at the 9th Asian Fisheries and Aquaculture Forum April 21-25, 2011, Shanghai, ChinaThis paper presents a post-hoc assessment of the introduction of intensive shrimp farming strategies, with and without green-water (GW) technology, in the Mahakam Delta where extensive systems (ES) dominate. The study also assesses the potential of integrated mangrove GW shrimp production (MGW). The method section describes the systems considered, the cost-benefit analysis applied and the assumptions for different scenarios. The data for the GW and non-GW systems were based on a survey in the Philippines. Assessing cultured shrimp yields from the total farm area showed that production from non-GW was 10% higher than from GW farms. Compared to these two systems, the MGW system produces about 20% of the total shrimp, but provides complementary livelihood options and ecosystem services. Per unit area covered, MGW system produces 20 times more shrimp than ES, while income for farmers doubles and opportunities for livelihoods enhancement associated with the mangrove area increase. Low operating costs make the ES interesting for resource poor farmers, but risks to producers and societal cost are underrated. Transferring from ES to MGW system will increase the contribution to the national economy whilst maintaining ecosystem services, that would otherwise be lost, were intensive culture systems to predominate.Preparation of this paper was supported by the MANGROVE project which received research funding from the European Community’s Sixth Framework Programme [Contract: INCO-CT-2005-003697], and from the RESCOPAR project funded by the INREF programme of Wageningen University. This publication reflects the authors’ views and the European Community is not liable for any use that may be made of the information contained herein