Practical technique for artificial propagation of Japanese pearl oyster (Pinctada fucata)

"The present paper is the manual, which is based on the previous papers under some corrections, on the artificial propagation of Japanese pearl oyster. We dealt with the food algae (Pavlova lutheri) production in Chap. 1, larval and spats rearing in Chap. 2, and adults rearing in Chap. 3. In Chap. 1, at the beginning, the cultivation method of food alga and the practical examples of food alga production in Mie Prefectural Fish Farming Center (1984) were introduced. And it was showed that in thermostatic room the cultivation of food alga was very stable, so the food production could be carried out as scheduled. The next, the changes of cell volume in mass cultivation processes of food algae and the relation between cell volume and carbohydrate content were detailed. Cell growth, which means the increase of cell volume and cell number (density), was affected by the condition of inoculated preliminary cultures. When the old preliminary cultures as in late stationary growth phase were inoculated into the medium for mass cultivation, cell density increased irregularly and at the same time cell volume was varied within the range of about twice difference. While when the mass cultures in logarithmic growth phase were inoculated successively to one after another, cell volume was almost invariable and small. Carbohydrate content per cell, which was important nutrition for shell, increased in proportion to the growth in cell volume and it was confered from the ratio (nitrogen content/chloroplyll-a content) that protein content also increased with the growth in cell volume. From these experimental results it was concluded that we should pay attention not only to cell number but also to cell volume to grasp the acculate ingested amount of nutrition by larvae. The results of experiments on the suppession factor of cell growth showed that the products of food alga in Mie Prefectural Fish Farming Center were not suppressed by medium and aeration but by light intensity. But it was also showed that if the more fluorescent lamps were added to, light efficiency (increment of cell growth/fluorescent lamp) would be declined. In Chap. 2, in rearing of swimming larvae, it was observed that ingested amount of alga (cells/larva/day), which was highly correlated with larval growth, was definit for larval size, and it was rapidly increased as larvae grew especially after umbo stage. Therefore, it seemed to be the simple and good rearing method to regulate the density both of larvae and of food algae on the basis of adequate feeding rate at which larvae ingest sufficient amount of food. From the results of several examples reared by the above-mentioned reasonable method in"