Studies on technique for artificial breeding of Urechis unicinctus

Studies were carried out on the technique for artificial breeding of Urechis unicinctus during 1993-1995. The Urechis unicinctus is gonochorism. Its spawning season is during April-May along the Yantai coast with the water temperature at 9-12 degree C. The collected eggs and sperms were artificially induced with a shade-dried and temperature dropped method or a anatomical method. When the density of hatching fertilized eggs was 150 eggs/ml at the water temperature 15 degree C, the hatching rate was about 75%. The water temperature of rearing larvae at 15-22 degree C. The rearing density of trachophora larva, somite larva, smoite larva and worm-shaped larva was 1-4 larvae/ml and 0.3-1 larva/ml, respectively. The feed were Isochrysis galbana 3011, Nitzschia closerium, Platymonas sp. and Chlorella sp.. When somite larva changed into worm-shaped larva in the 28-30th day after fertilization, sands should be covered in pool bottom for seed-collecting. The rate of metamorphosis was 68-88%. Ten days later, young Urec