Inland shrimp farming in Thailand.

In Thailand, marine shrimp was traditionally produced extensively for decades in coastal ponds. The insatiable global demand for shrimp products in recent years intensified and expanded shrimp culture in Thailand throughout the 1990s. Few regulations or guidelines were imposed on developing coastal land for shrimp farming. The boom resulted in rapid degradation of the coastal environment and widespread disease outbreaks, causing repeated crop failures in shrimp culture. In contrast, shrimp cultured in low-salinity ponds away from the coast experienced great success. As a result, thousands of hectares of rice paddies in the Thai heartland distant from the seacoast were converted to low-salinity shrimp farming. Large quantities of high-salinity brine (100-200 ppt) were transported from coastal salt pans to fill inland ponds to a salinity less than 5 ppt. Other than the salinity difference, low-salinity shrimp culture was generally similar to that in the coastal ponds. Shrimp were stocked at high density (50-100 PLs m-2) in a closed system. The shrimp production commonly exceeded 10 t ha-1 crop-1 in 3-4 months. During the peak period, shrimp production from inland areas accounted for nearly 40% of total annual production of shrimp at 200,000 t in Thailand. As the economic gain from shrimp production was more than 50-fold that of the rice crop, shrimp culture was regarded as a bonanza for debt-ridden rice farmers. However, inland shrimp farming was short-lived, as the Thai government banned the practice in 1993 on the grounds that it led to salination of soil and groundwater, and ultimately jeopardized the national rice bowl. Despite the ban, low-salinity shrimp farming still exists in areas where intrusion of natural seawater occurs. However, with persistent disease problems encountered in culturing native Penaeus monodon, the exotic white shrimp (Litopenaeus vannamei) has become the major species.