Abstract

This study interested on spawning and early embryo development in surf clam, Tresus keenae. For spawning induction, we performed natural spawning, physical stimulus (temperature, air dry), freshwater stimulus and chemical stimulus (sperm suspension). In addition, the sperm amounts were differently treated during artificial insemination and were investigated optimal amount of sperm through fertilization rate and hatching rate. The effects of water temperature and salinity on early embryo development were also investigated. Result that, the physical stimulation method was the most effective method with 35% efficiency in inducing spawning. The fertilization rate and hatching rate were best when $50{\times}10^4inds./egg$ sperm were used for artificial insemination. The effects of water temperature and salinity on reaction velocity of embryogenesis were investigated. The fast velocity of embryogenesis had the water temperature was higher and salinity concentration was close to natural condition.