Conditions for collective action: Understanding factors supporting and constraining community-based fish culture in Bangladesh, Cambodia and Vietnam

Flood-prone ecosystems in South and Southeast Asia are traditionally farmed with deepwater rice followed by post-flood rice culture during the dry season. During the flood season, the same land is inundated, creating an open-access water body subject to multiple uses by multiple users. Fish production in these areas is based on the capture of wild fish. In these seasonal flood plains, fish are trapped in rice fields, reproduce and are harvested by farmerfishers or full-time fishers. These flooded areas cover about 4.5 million hectares in Bangladesh, and 1.2-1.4 million hectares (Catling 1992) is deeply flooded in the Mekong Delta of Vietnam and Cambodia for 4 to 6 months each year. One option to improve access to protein and diversified income for local users and to improve water-use efficiency is to integrate fish culture into this system. A number of studies conducted in the 1980s tested the technical feasibility of culturing fish in seasonally flooded rice fields (Roy et al. 1990, Mukhopadhyay et al. 1992, Rothuis et al. 1998a, Rothuis et al. 1998b, Ali et al. 1998). These studies showed that fish production could be increased by more than 1 ton per hectare per year (t/ha/yr) by stocking fish in flooded rice fields in individual plots. Based on these findings, the WorldFish Center implemented between 1997 and 2000 on-farm experimental trials of community-based fish culture (CBFC) on the Ganges and Meghna floodplains of Bangladesh and the Red River and Mekong deltas in Vietnam (WorldFish 2002). Farms are cultivated individually during the dry season, but during the flood season individual landholding boundaries disappear under the water, and water bodies and flooded rice field resources become common property. The project was based on the premise that production from these water bodies could be enhanced by stocking locally important fish species, providing communities with an additional source of income and an increased supply of affordable fish for sale or consumption (e.g., Dey and Prein 2003, IIRR 2000, Sinhababu et al. 1984). The results showed that fish production can be increased, with an average of 226 kilograms (kg)/ha in Vietnam and 863 kg/ha in Bangladesh, with a significant improvement of the household income (Dey et al. 2005). CBFC was found technically and economically sound and socially acceptable. However, the project concluded that further research was needed to understand how the institutional mechanisms needed to support fish culture differ in a range of different contexts. From 2005 to 2010, the Challenge Program on Water and Food project Communitybased Fish Culture in Seasonal Floodplains developed a series of trials to test this technology under different environmental and socioeconomic conditions. The objective of the project was to test the feasibility of this approach to improve water-use efficiency and provide benefits to the various users of seasonally flooded rice fields. Technical and economic aspects were monitored, and locally appropriate group arrangements for fish culture management, benefit sharing and resource access were tested. Although the technical and environmental aspects of culture-based fisheries in various countries are well documented (De Silva 2003, Nguyen et al. 2001, De Silva etal. 2006), CBFC in seasonal floodplains is a relatively new concept, and the suitability of this approach in different contexts remains under question. The project aimed to address this issue by developing onfarm trials in seasonally flooding areas with otherwise contrasting socioeconomic and natural environments. In this report, we focus on a study designed to understand the factors and conditons that support or constrain the feasibility and uptake of community-based fish culture in seasonal floodplains. The aim of the study is to contribute to knowledge on institutions for collective action, and the feasibility of community-based approaches to resource management, based on lessons learned in this 5-year project. The study also offers useful lessons for project implementation in the field of research-for-development. The report begins with an introduction to the Community-based Fish Culture project and a description of the technical intervention. The second part of the report introduces the study to investigate the conditions for collective action in community-based fish culture, beginning with a presentation of the research approach and methodology. The third section presents the findings of the study. Finally, we present a synthesis of the factors supporing and constraining community-based fish culture, key lessons learned and recommendations

Efficient and versatile manipulation of the peripheral CD4+ T-cell compartment by antigen targeting to DNGR-1/CLEC9A

DC NK lectin group receptor-1 (DNGR-1, also known as CLEC9A) is a C-type lectin receptor expressed by mouse CD8α+ DC and by their putative equivalents in human. DNGR-1 senses necrosis and regulates CD8+ T-cell cross-priming to dead-cell-associated antigens. In addition, DNGR-1 is a target for selective in vivo delivery of antigens to DC and the induction of CD8+ T-cell and Ab responses. In this study, we evaluated whether DNGR-1 targeting can be additionally used to manipulate antigen-specific CD4+ T lymphocytes. Injection of small amounts of antigen-coupled anti-DNGR-1 mAb into mice promoted MHC class II antigen presentation selectively by CD8α+ DC. In the steady state, this was sufficient to induce proliferation of antigen-specific naïve CD4+ T cells and to drive their differentiation into Foxp3+ regulatory lymphocytes. Co-administration of adjuvants prevented this induction of tolerance and promoted immunity. Notably, distinct adjuvants allowed qualitative modulation of CD4+ T-cell behavior: poly I:C induced a strong IL-12-independent Th1 response, whereas curdlan led to the priming of Th17 cells. Thus, antigen targeting to DNGR-1 is a versatile approach for inducing functionally distinct CD4+ T-cell responses. Given the restricted pattern of expression of DNGR-1 across species, this strategy could prove useful for developing immunotherapy protocols in humans