There was a drastic decline in global mangrove area during the 1980s and 19990s, but since 2000 the annual loss rate has declined to about 0.38% of global mangrove area. During the 1980s and 1990s, somewhere between 30% and 80% of mangrove loss could have been caused by shrimp farming. The actual percentage cannot be determined, because there are other causes of mangrove loss including conversion to fish ponds. The present-day loss of mangrove area to shrimp farming is less than in the past. In the five countries of this study, the entire loss of mangrove area since 2000 in Ecuador, India, and Vietnam could be attributed to shrimp farming if you assume no other driver of mangrove area loss - a dubious assumption. The loss of mangrove area in Thailand and Indonesia is much greater than the expansion of the shrimp farming area. In fact, in Thailand, the shrimp farming area has declined since 2000.
Most shrimp farming areas located in the tidal zone (where mangrove habitat is located) are for extensive production of Penaeus monodon. Mangrove areas are not well-suited for construction and operation of shrimp farms, and the income from extensive shrimp farming in mangrove areas is very low compared to the value of ecological services from mangrove areas. The annual income from intensive shrimp farming is typically less than 2,000 USD/ha/yr. Moreover, many crops fail and produce no income. The annual value of mangrove area for direct and indirect ecological services is usually several thousand USD/ha/yr. There seems no justification for national governments and NGOs encouraging small-holder shrimp farms to use mangrove areas for shrimp production even as a means of poverty alleviation.
It would seem reasonable for governments to give small-holder shrimp farmers an economic incentive to close their farms. The national value per hectare of mangrove areas for ecological services is many times greater than the income possible per hectare of extensive shrimp farms.