are placed in freshwater for 1 hr to kill flatworms. 

 P\eiid(>M\li>cluis sp. After a quick saltwater dip (5 to 

 10 sec), 750 spat-laden shells are placed in shipping 

 cases. Before wrapping, a random sample of 50 

 shells are taken out of the case and the number of 

 seeds counted. Within 48 hr after crating, the seeds 

 reach France. 



The French's interest in Japanese seed has come 

 about only in recent years. Heavy mortalities have 

 occurred among the Portuguese oyster. Cmssostrea 

 ani^iihita. in France, and the government has banned 

 the importation of Portuguese oyster seed in their 

 country. In its place, they are now importing seed 

 from Japan. 



The new competition for Japanese seed could 

 have two implications in the U.S. Pacific coast oys- 

 ter industry: 1) the cost of Japanese seed to the 

 United States could increase, and 2) because the 

 French have entered the market, there could de- 

 velop a possible shortage of Japanese seed for im- 

 portation to the United States. In 1972, heavy sets of 

 Pacific oysters occurred on the west coast, so the 

 need for Japanese seed, at least in that year, was 

 considerably less. 



About 77% of the total oyster production in Japan 

 comes from Hiroshima Prefecture (31,188 tons of 

 meat out of a 1968 total of 40,928 tons). Furukawa 

 (1971) states that a total of 10,962 rafts (9.1 x 18.2 m 

 average size) are utilized in the Prefecture. 



During our tour of the area, seed oysters were 

 being strung on galvanized wire and suspended from 

 bamboo rafts. Initially, 1.600 strings (wrens) are 

 suspended. As the oysters grow, the number per raft 

 is reduced to 800. On each string, about 15 m long, 

 spat bearing scallop shells are separated by a 9-inch 

 bamboo spacer. 



Each raft is constructed out of bamboo logs. A 

 typical raft. 20 x 9 m, is supported by 25 styrofoam 

 floats, each the size of a 50-gal oil drum. Fifteen 

 floats are located down the center of the raft while 

 two series of five floats are located along the outer 

 edge. An iron cable runs down the center of the raft 

 and is the connecting link between each series of four 

 or five rafts. The rafts are held in place by six (5 tons 

 each) concrete anchors. A typical raft, including 

 labor, costs about $350 and takes a crew of four 1 day 

 to build. 



As in Miyagi Prefecture, the entire industry is 

 dependent on natural setting. No attempt is being 

 made to supplement natural sets with hatchery- 

 reared stocks. The seed is caught in the intertidal 

 zone on scalli^p shells draped over racks. 



Several problems are facing the oyster industry of 

 Japan. Of considerable concern is the increased 

 threat of both domestic and industrial pollution. In- 

 dustries are located in areas adjacent to oyster grow- 

 ing and setting areas. Further expansion of such 

 industries could seriously affect the oyster industry. 



Because the bulk of oysters in Japan are grown 

 off-bottom, a considerable amount of labor is in- 

 volved. In recent years, there has developed a seri- 

 ous labor shortage in the oyster industry. Young 

 people do not wish to follow their parents in this line 

 of work. Thus, simplification of techniques and de- 

 velopment of mechanization in the oyster industry is 

 urgently needed (Fujiya. 1970). 



ABALONE 



Abalone production in Japan has increased from 

 4.600 metric tons in 1964 to 6.500 metric tons in 1970. 

 One possible reason for this increase is the effect of a 

 large seed planting program. According to Sanders 

 (1971). there are 16 laboratories in Japan artificially 

 producing 2 to 3 million seed abalone annually. 



A typical laboratory is the Kanagawa Prefectural 

 Fisheries Experimental Station located on the island 

 of Joga Shima near the City of Miura. Their quota, 

 which is set by the government, is to produce about 

 300, OOA seed abalone annually. 



At the Station, mature abalone are induced to 

 spawn by first air-drying and then placing them in 

 shallow, standing water tanks which are exposed to 

 sunlight. Apparently as the sunlight heats the water, 

 the abalone spawn. 



The fertile eggs are transferred to setting tanks 

 located inside an adjacent building. These tanks are 

 covered with black plastic sheeting to eliminate 

 light. The larvae, which require no supplementary 

 feeding, set in about 1 week on special plastic plates. 

 These plates have been previously exposed to run- 

 ning seawater in order to obtain a film of diatoms, the 

 food of young abalone. Since the larvae swim near 

 the surface, the water is slowly raised in the setting 

 tanks so that the setting abalone are distributed as 

 evenly as possible on the plates. Once setting is 

 over, the plates are transferred to outdoor tanks 

 where the abalone continue to feed on the diatom 

 film until they reach 5 to 10 mm in size. They are then 

 removed from the plates and placed on either tiles, 

 oyster shells, stones, or cross-shaped plastic config- 

 urations. At this stage, they are fed macroscopic 

 algae such as Ulva and Laminur'ui. When the 

 abalone are approximately 2.5 cm in size (about 8 mo 



108 



