The onset and withdrawal of the rainy season in Thailand and their effects on oyster farming

Abstract

Oyster farming is among the main economic activities in eastern Thailand. The timing of when to harvest and to seed the new mollusk larvae is determined by the salinity of the river, which in turn depends on the influence of the monsoon. The harvest has to be carried out before a mass of fresh water flows down the river in July. The farmers seed the larvae for the next year’s products in December. Global warming potentially extends and intensifies the rainy season, disrupting the harvest cycle and harming oyster products. This research attempts to predict when the rainy season will end by looking at the relationship between the onset of the season in May and the withdrawal in October. Based on statistical analysis, years with an early onset have a late withdrawal, and years with a late onset have an early withdrawal. This knowledge can help farmers decide when to seed the mollusk larvae, and is a useful adaptation tool in dealing with the effects of global warming.