the surface. It is from this lower line that seed collec- 

 tors and cages for growing scallops are attached. 



Scallop spawning in Mutsu Bay begins in March, 

 peaks in early April, and is over by mid-April. The 

 larvae life is about 35 days (temperature during this 

 period ranges from 7° to 12°C). The fishermen put 

 out their seed collectors in early May. 



Initially, seed scallops were caught on suspended 

 Cyprus branches, but now over 50% of the collectors 

 consist of plastic web bags filled with used gill nets. 

 Eventually, most collectors will be of this type. In 

 1971. 2.3 million bag collectors were used and 40 

 billion seeds were collected in Mutsu Bay. 



Before the young scallops lose their byssal 

 threads, they are removed from the bags and placed 

 in pearl nets. As the scallops grow, they are transfer- 

 red to new pearl nets with larger mesh size. At about 

 4 cm, the scallops are either planted on the bottom or 

 placed in circular or book nets and resuspended from 

 the longline. The suspended scallops reach commer- 

 cial size, 10.5 to 1 1.0 cm, in about 2 yr. It costs the 

 fisherman approximately 14 yen/scallop to raise it to 

 market size using the longline method. In turn, he 

 can sell the scallop for 30 to 60 yen apiece. 



Unlike the sea scallop fishery of the United 

 States, the Japanese save all the scallop shells. 

 These are bagged and shipped to the Inland Sea 

 where they are used as cultch for catching seed oys- 

 ters. 



One of the principal laboratories involved in sea 

 scallop research is the Aquaculture Center located 

 on Mutsu Bay near the City of Asamushi at the 

 northern end of Japan's main island of Honshu. The 

 Center is a new installation that opened in April 

 1968. One of its largest programs is related to the 

 propagation of sea scallops. Their goal is to produce 

 1 million seed scallops annually using hatchery tech- 

 niques. 



The Oyster Research Institute is also culturing 

 sea scallops at their tank farm. 



Scallops are induced to spawn using both natural 

 and conditioned stocks. Over 200.000 seed scallops 

 are cultured annually. They are suspended from the 

 tank farm in book nets, circular nets, and pearl nets 



until a size of 2 to 3 cm is obtained. The scallops are 

 then sold to local fishermen who grow them sus- 

 pended from rafts. When the scallops are approxi- 

 mately 5 cm in size, the fisherman drills a hole in the 

 ear(wing)of the scallop, threads a nylon line through 

 the hole, and ties it to ropes suspended from rafts. 

 They reach market size (12 cm) in about 2 yr (Cost- 

 low, 1969). 



LITERATURE CITED 



AUSTRALIAN FISHERIES. 



1971. Australian studies Japanese fish culture techniques. 

 Aust. Fish. 30(IO):3-7. 9. 

 COSTLOW. J. D. JR. (editor). 



1969. Marine biology. Vol. V. Proceedings of the Fifth In- 

 terdisciplinary Conference on Marine Biology. Gordon 

 and Breach. New York. 606 p. 



FUJIYA, M. 



1970. Oyster farming in Japan. Helgolaender wiss. 

 Meeresunters. 20:464-479. 



FURUKAWA, A. 



1971. Outline of the Japanese marine aquiculture. Jap. 

 Fish. Resour. Conserv. Assoc. Tokyo, .39 p. 



IMAI, T. 



1 967. Mass production of molluscs by means of rearing the 

 larvae in tanks. Venus 25:159-167. 



JAPANESE FISHERIES ASSOCIATION. 



1971. Fisheries of Japan - 1971. Jap. Fish. Assoc. Tokyo, 

 45 p. 

 KAN-NO, H., M. SASAKI. Y. SAKURAI. T. WATANABE. 

 and K. SUSUKl. 

 1965. Studies on the mass mortality of the oyster in Mat- 

 sushima Bay. 1. General aspects of the mass mortality of 

 the oyster in Matsushima Bay and its environmental condi- 

 tions. [In Japanese. English abstr.] Bull. Tohoku Reg. 

 Fish. Res. Lab. 25:1-26. 

 RYTHER. J. H. 



1%8. Invertebrate and algae culture. In The status and 

 potential of aquaculture. particularly invertebrate and 

 algae cultures. Vol. I. Part U. p. 1-261. .Am Inst. Biol. 

 Sci.. Washington. DC . ( Distrib. by: Clgh. Fed. Sci. Tech. 

 Inf.. Springfield. Va.. as PB 177 767.) 

 R'l THER. J. H.. and J. E. BARDACH. 



1968. The status and potential of aquaculture. In The status 

 and potential of aquaculture. particularly invertebrate and 

 algae culture. Vol. I, Part I, p. 1-45. Am. Inst. Biol. Sci.. 

 Washington. D.C. (Distrib. by: Clgh. Fed. Sci. Tech. Inf.. 

 Sprmgfield. Va.. as PB 177 767.) 



110 



