Asian hard clam (Meretrix sp.) is an economically important shellfish species in Taiwan. It naturally inhabits the lower reaches of sandy beaches, estuaries and tidal flats areas. The average annual yield in recent decades has been 54,000 tons, with an average annual value of 105 million US dollars, according to the fishery statistics of Fisheries Agency, Council of Agriculture, Executive Yuan, Taiwan. The Tamsui River estuary was once the major production area for wild clam seed in Taiwan. However, as a result of environmental changes within the estuary, associated, in part, by increases in adjacent farming activities, the production of clams from the Tamsui River estuary has decreased year by year. The aim of this study is to investigate the environmental factors associated with a suitable habitat for clams, and to quantify the stocking status for Asian hard clams. Meat Yield and histological examinations of the gonads can be applied to estimate the reproductive cycle. It is necessary for developing sustainable management strategies and broodstock selection for Asian hard clam in aquaculture development. During this investigation, the abundance of Asian hard clams was highest at the Mangrove station of the Tamsui River, with the abundance decreasing toward the river month of the estuary. The abundance of juvenile was also higher in the upper reaches of the Tamsui River estuary. The length-weight relationship of the clam is TW = 5.747 × 10-4SL 2.805. The maturity of clams at the Tamsui River begins in April each year, and more juveniles begin to appear in August. The results of this study also found that the abundance of clams has the highest correlation with water temperature, followed by the concentration of chlorophyll-α in the water close to the river bottom, both of which are positively correlated. The dissolved oxygen in the water, the concentration of chlorophyll-α on the surface of the sediment and pH are directly negatively correlated with the abundance of clams.