This study reviewed mangrove-shrimp farming systems to determine the factors affecting their yield, income, and biodiversity services contributions. Three types of mangrove-shrimp farming systems are distinguished: a) integrated systems with shrimp raised in ditches between bunds with mangrove; b) associated systems having larger areas of water connected with a large mangrove covered area; and c) separated systems with a dike separating the ponds and the forest (See Figures a, b and c, respectively). The latter uses the mangrove to filter the effluent water before releasing. Reviewed studies attributed the wide variation in shrimp yield of the integrated and associated (i.e. mixed) systems to water exchange, % of water surface, mangrove species, primary production, cover and age, leaf litter fall and decomposition, and predators, among others. Leave litter of most species affected water quality, except for Nypah palm. Leaves' composition and decomposition rate varied between species; the latter increased when submersed. Some leave (litters) contain antiviral components and have (temporary) a positive effect on shrimp health and growth. While timber production peaks at 55% forest stand, the shrimp yield was higher with a mangrove cover of 30 to 50%. Annual benefit-cost ratio in integrated systems was better than that in the associated systems, but one study found higher long term cost-benefit ratios for the latter. To keep water quality within the limits acceptable for shrimp, water needs to be refreshed regularly and ditches dredged. The design of most Vietnamese mixed systems does not allow frequent inundation of the mangroves, thus limiting timber production. The contribution of mixed systems to biodiversity and to the ecosystem services is limited, and their farm area needs to be 10 ha at least to give farmers a decent livelihood. Partly separated systems have a higher potential to contribute to ecological, economic and social sustainability (Figure d). To promote partly separated ecological mangrove-shrimp systems, implementers can enhance its economic returns by capitalizing on ecosystem services through carbon credits and through organic certification. The latter needs to include the neighbouring forest area when judging for compliance.
|Publication status||Published - 2014|
|Event||International Conference “Aquaculture and Environment: a focus in the Mekong Delta, VietNam" - |
Duration: 3 Apr 2014 → 5 Apr 2014
|Conference||International Conference “Aquaculture and Environment: a focus in the Mekong Delta, VietNam"|
|Period||3/04/14 → 5/04/14|