Pond Cultivation
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Yanase’s pond was near his breeding pool, just across the dyke from his main mussel-holding area at the mouth of the Sakuragawa river. Breeding juvenile mussels (raising spat) has been done in pools for years, but adult, especially pearl-operated mussels have needed natural water. Using water mixed from river and tap, and chicken-manure compost to nourish plankton, a good survival rate was maintained. However, pearl growth speed lagged behind that acheived in flowing river water. No previous attempts to cultivate pearls in a pond are known. The project failed because, during Yanase’s 2-day absence from the farm, crabs made a hole that drained the pond, with a total loss of mussels and pearls.
This was before the 2003 blight, which decimated the carp (koi) farming and wiped out freshwater pearl farming elsewhere in Japan. By some unprecedented fluke, some 20% of pearl-operated mussels in the Kasumi-ga-Ura area survived, but the Sakuragawa site became unusable. Yanase would have moved his mussels years earlier, but was denied permits by buerocrats, some of whom have appear to bear a grudge against fw pearl cultivators.