sold to the dealers, who preserve the products and 

 sell them to consumers. Each Japanese eats an aver- 

 age of 50-60 sheets of nori per year. Nori is rich in 

 vitamins, and two sheets of nori can supply one 

 daily dose of them. 



Processing in Actual Nori Cultivation 



Seed. — Present cultivation depends completely on 

 the spores from cultured Conchocelis. The culture is 

 done by each fisherman or by his cooperative union. 

 The culture begins at the end of the last season. 

 Many cleaned oyster shells are spread on the bottom 

 of shallow tanks filled with seawater. Cut pieces of 

 mature nori plants are put on the water, so that the 

 carpospores released from the plant will attach 

 themselves to the shells and develop to the Con- 

 chocelis phase on them. Shells with Conchocelis are 

 hung down in other tanks 0.5- 1 .0 m in depth, where 

 they are kept throughout the summer. The water in 

 the tanks is changed if it becomes dirty. Light in the 

 tanks is controlled so that Conchocelis grows well 

 without getting ill. At the end of summer, the Con- 

 chocelis matures and produces many spores which 

 develop into nori buds. 



In the fall, when the seawater temperature goes 

 dow n below 24°C, fishermen prepare the cultivation. 

 Twenty to forty nets are set in a layer in the sea. 

 Shells with fertile Conchocelis are put into many 

 vinyl bags, and these are hung just under the nets in 

 order to have the spore find the collector as they 

 come out of the bag. Sometimes the net layer is put 

 into a large polyethylene bag with Conchocelis and 

 left floating on the surface of the sea. This method 

 prevents the cultivator from wasting spores and can 

 also be done in deeper waters. After several days, 

 when the spores have fixed themselves to the nets, 

 these nets are taken out from the bag and are tied to 

 the poles for spore development. 



Biiiii;inii up ofyoiiiii; hints. -A set of 20-40 layered 

 nets is separated into sets of 5-6 layered nets, which 

 are then separated into single nets, as the buds grow. 

 In the process of separation, when the buds are 5-50 

 mm in length, the necessary amount of nets with 

 buds are taken out of the water, dried and stored in 

 refrigerators set at -20°C. Here the buds are kept 

 alive, preparing for the recovery of crops when the 

 planted nori suffers from a prevailing disease or a 

 heavy storm. Fishermen always control the level of 

 nets as the climate and the tide changes, so that the 

 buds do not suffer from severe drying out in low tide 

 and alsi) from mowth of weeds and diatoms. 



Reiirini; of nori pUiiils iiiiil their luirvesl. -.\boul 

 50 days after budding, nori plants grow to 15-20 cm in 

 length and then are harvested. After the first harvest 

 many buds remain on the nets, promising another 

 harvest in 15-20 days. In this way harvesting can be 

 repeated several times from a net throughout the nori 

 season. But generally the crop decreases in repeat- 

 ing harvests; sometimes the crop may die from the 

 diseases of nori or by some accident. Then, the cul- 

 tivators replace these nets with the refrigerated ones 

 that can replace the crop in 15-30 days. 



Harvesting is done by using machines which make 

 the labor at sea more comfortable and etTicii-nt. 



Manufactitrinii paperlike dried prodiicls from 

 cropped nori. — Cropped nori plants are cleaned by 

 washing with seawater. Then they are chopped and 

 spread on screens made of fine twigs of bamboo orot 

 fine plastic rods and finally dried in a dryer with an 

 old burner. Drying has to be done quickly at low 

 temperatures, commonly in 2-3 hrwith the tempera- 

 ture lower than 50°C. In these conditions nori is kept 

 alive until the end of the drying procedure. This 

 makes the product glossy, tasty, and sweet smelling, 

 and retains all vitamins. 



Recent Advances in Culture Techniques 



Recent yearly changes of nori production is shown 

 in Figure I, with changes of numbers of cultivating 

 sets, of nets used, and of nets stored in refrigerators. 

 The overall nori production has increased year by 

 year but show sharp fluctuations. In these days 

 progress in culture techniques has tended towards I ) 

 new methods on how to expand the nori grounds. 2) 

 how to prevent sharp declines in the yearly produc- 

 tion, and 3) how to reduce labor in culti\ation and to 

 make laborers more comfortable. 



Techniques to prevent sharp declines in the yearly 

 production. -O^ course, nori growth is affected by 

 certain conditions, especially by the climate in the 

 growing season. But the sharp drops in production 

 were caused by severe outbreaks of diseases which 

 occur successively in important grounds. It was 

 found that the disease occurs in connection with 

 overpopulation of the plants on the grounds — setting 

 of too many nets for greater harvest. This finding led 

 to the development of the techniques to get a far 

 more stable cropb\ controlling the amount of nets to 

 be set on a ground. 



The technique to store live nori buds in cold stor- 

 age was first applied in 196.^, making it possible for 



10 



