Mytilus edulis L. is a coldwater bivalve mollusc. The southern limit of its geographical distribution along the China coast is Jiaozhou Bay where it is commonly found only on harbour wharves or on ships. Since 1958, the Institute of Oceanology. Academia Sinica and the Qingdao Mariculture Station repeatedly transplanted seed mussels collected from Yantai (Shandong Province) and Dalian (Liaoning Province) to Qingdao for experiment culture, but failed finally in their efforts to propagate them. Owing to the mass culture that was constant1y expanding in 1975 and 1976, the use of waste ropes discarded after the harvesting of Laminaria as spat collectors was widely popularized in Jiaonan County, as a result of which there was a great increase in the amount of spats collected. Investigations showed that during 1974-1976, the amount of spats collected from the various culture grounds annually increased many times, even to tens of times (Tab. 2) From Tab. 3 it can be seen that by 1975， the number of spats collected amounted to 400 million, and by 1976 to 2900 million.