The purple dye snail Plicopurpura pansa is recognized as the most important species within the Huatulco National Park (HNP) because its dye is used by Mexican ethnic groups from Oaxaca to dye cotton yarn used to produce ceremonial clothing with cultural value. In the HNP, reproductive and recruitment seasons of this species are scarcely documented, and this information is essential to understand its complete life cycle. The aim of this study was thus to establish when reproductive and recruitment seasons began, reached their maximum, and ended in the HNP. Snail length records were obtained for both sexes, and the mean value of age was estimated using length parameters reported in the literature. For each of the estimated age classes, ranging from 0.5- to 4-y-olds, snail abundance was calculated on a monthly basis. Based on a monthly natural mortality rate estimate of 0.53, virtual population analysis was performed to obtain two population indices: (1) snail spawner virtual abundance (or SS index), and (2) snail recruit virtual abundance (or SR index). The SS and SR indices were subjected to time series analysis. With the SS index, a complete reproductive season spanned from March to October/November, with maximum abundance of spawners during June/July; reproductive recovery was observed from October/November to March, between reproductive seasons. With the SR index, a complete recruitment season spanned from August to January/February with a maximum abundance of recruits during November/December. Monthly sea surface temperature changes showed a significant positive correlation with the SS index, and a significant negative correlation with the SR index. Results provide evidence that cultural exploitation is negatively affecting these snails, and support the view that this population is being overexploited within the HNP. Recommendations for improved management of this resource that will prevent its overexploitation are proposed.