Comparative Studies Of Pearl Production Between Hyriopsis Schlegeli And H. Cumingii

Hyriopsis schlegelii which was original distributed in Japan is the famous freshwater clam, it is various species of the genus Hyriopsis cumingii which was original distributed in China. It was introduced into China by Nancheng Reservoir Exploitation Company in Fuzhou in 1997. In this research, we focus on the biological characteristics, propagation and artificial breeding techniques and pearl performance characteristics. In order to provide some theoretical and practice instructions of freshwater pearl cultivation in our country, to work out the problem of unitary species of pearl clam, to promote a healthy and sustainable development of freshwater pearl cultivation.First, the biological characters were investigated. The external and internal morphology of H, schlegelii are almost as same as H.cumingii wit regional variations. The countable and measurable properties data indicated that shell width of H. schlegeli is as 1.23 times as H.cumingii. Paraffin section and SEM (Scanning Electron Microscope) observations showed the crystalline style of H. schlegeli is longer and larger diameter than H.cumingii, the mantle depth of H. schlegeli is as1.78 times as H.cumingii, and the nacre shell is 2.08 times. The average growth speed of H. schlegeli is faster than, which were the same sizes, culture density and cultured in the same water. Compared 1-year-old and 2-year-old H. schlegeli with H.cumingii, as to shell weight, the former is heavier by 4.99% , 2.28% than the latter; body weight, 6.05%, 4.57%; total weight, 5.45%, 3.21%; survival rate, 11.07%, 10.11%.Second, pearl performance was carried out on H. schlegeli and H.cumingii, including nucleated pearl producing and all-nacre pearl producing. The results indicated H. schlegeli has significantly high advantage in pearl performance than H.cumingii. The survival rate of operative mussel of H.schlegeli was higher than H.cumingii both of nucleated pearl producing and all-nacre pearl producing. Meanwhile, the yield makes the difference. The pearl yield of each H. schlegeli ranges up to 14.84g, 1.18 times of H.cumingii.The results indicated that H. schlegeli has best morphology for culturing pearl, the propagation and artificial breeding techniques were matured, the pearl performance was better H.cumingii. It can be widely use in freshwater pearl cultivation in our country.