Shrimp Farms

[blank] the past two decades, around a third of the world's mangrove swamps have been converted for human use, with many turned into valuable shrimp farms. In 2007 an economic study of such shrimp farms in Thailand [blank] that the commercial profits per hectare were $9,632. If that were the only factor, conversion would seem an excellent idea. [blank] , proper accounting shows that for each hectare government subsidies formed $8,412 of this figure and there were costs, too :$1,000 for pollution and $12,392 for losses to ecosystem services. These [blank] damage to the supply of food and medicine that people had taken from the forest, the loss of habitats for fish, and less buffering against storms. And because a given shrimp farm only [blank] productive for three or four years, there was the additional cost of restoring them afterwards.