Low larval survival,poor settlement,and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina.We examined the effects of chemical cues including epinephrine,nor-epinephrine,and serotonin on larval survival,settlement,and metamorphosis in order to determine the possibility of using these chemicals to induce the problems.The results show that epinephrine could enhance metamorphosis rate at 10-6 mol/L only but higher concentrations(10-3-10-4 mol/L);and nor-epinephrine could inhibit the performance significantly,and serotonin could increase significantly the performance at a wide-range concentration(10-3-10-6 mol/L).Treatment with serotonin at 10-5 mol/L for 72 hours resulted in the highest settlement rate(42.2%) and survival rate(49.3%),while at 10-4 mol/L for 72 hours resulted in the highest metamorphosis rate(38.8%).Therefore,serotonin may be used as a fast metamorphosis inducer in abalone culture. Low larval survival, poor settlement, and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina. We examined the effects of chemical cues including epinephrine, nor-epinephrine, and serotonin on larval survival, settlement, and metamorphosis in order to determine the possibility of using these chemicals to induce the problems. results show that epinephrine could enhance metamorphosis rate at 10-6 mol / L only but higher concentrations (10-3-10-4 mol / L); and nor-epinephrine could inhibit the performance significantly, and serotonin could increase significantly the performance at a wide-range concentration (10-3-10-6 mol / L). Treatment with serotonin at 10-5 mol / L for 72 hours resulted in the highest settlement (42.2%) and survival rate (49.3%), while at 10-4 mol / L for 72 hours resulted in the highest metamorphosis rate (38.8%). Thus, serotonin may be used as a fast metamorphosis inducer in abalone culture.