The loss in wild fisheries stocks due to habitat conversion associated with shrimp farming is large. We estimate that a total of 400 g of fish and shrimp are lost from capture fisheries per
kilogram of shrimp farmed in Thai shrimp ponds developed in mangroves (Box 1). If other fish and shell®sh species caught in waterways adjoining mangrove areas are considered, the total
reduction increases to 447 g of wild fish biomass per kilogram of shrimp raised. If the full range of ecological effects associated with mangrove conversion is accounted for, including reduced mollusc productivity in mangroves and losses to seagrass beds and coral reefs, the net yield from these shrimp farms is low even without considering the use of fish meal in aquaculture feeds. Moreover, building aquaculture ponds in mangrove areas transforms fisheries from a common property resource available to multiple users to a privatized farm resource.