Today we left Wuxi City and drove for about three hours to Jinhua City. We had lunch with Professor Zhang Genfang, the owner and operator of a nearby pearl culture farm. He is also a teacher and researcher at Jinhua College of Profession and Technology. After lunch we drove outside of the city to his farm, the Jinhua Wellwant Freshwater Pearl Culture Farm.
His farm has many acres and consists of about a dozen large shallow ponds, where he holds 40,000-50,000 Hyriopsis cummingii, the mussel species used here for pearl culture. The mussels are held in baskets and are implanted with 12-14 pearls per mussel. The baskets are suspended off the pond bottom by empty plastic soda bottles. Suspending the baskets improves the growing and survival conditions for the mussels. Depending on yearly growing conditions, the mussels are held in the ponds for about 3-5 years before the pearls are harvested from the mussels. Prof. Zhang harvested pearls from 3 mussels. Very interesting to see how the pearls grow implanted inside the mantle and do not touch the shell. If the pearl breaks through the mantle and touches the shell, it will fuse with it, hence destroying the pearl.
One thing you notice at the farm, is the other fish species that are also being grown in the ponds with the mussels. Yellow eels, yellow catfish and carp for example, and even hot peppers along the pond banks. So the utility of the ponds and the farm is maximized.
After seeing the ponds, we walked over to his juvenile mussel rearing building. Very hot and humid inside! The juvenile rearing areas consisted of 4′ X 4′ shallow ponds, say about 4-5 inches deep. Water was gravity fed into the building from the main ponds. Yellow catfish is the host for Hyriopsis mussels and is used to produce the juveniles. He takes the glochidia (mussel larvae) from 1 female mussel and infests them on 15-20 young catfish about 4-6 inches long. The catfish act as the host for the larvae as they develop into juveniles. The larvae feed from the gills of the fish and are carried by the fish to areas they would otherwise not be able to colonize.
He then holds the small catfish in the square juvenile mussel rearing areas until the juveniles drop off the fish. He removes the catfish, and the juveniles then grow inside the shallow rearing areas. A different set-up compared to what we use in the United States, where we hold the infested fish in aquarium tanks.
Learn more about the mussel life cycle at: http://www.fws.gov/midwest/mussel/multimedia/life_cycle.html.
After you see such an operation, you begin to get new ideas for growing mussels back home. Seeing how they held the mussels suspended off the pond bottom was helpful to me.
The days photos can be found at: