STUDIES ON THE GROWTH OF LAMPROTULA FIBROSA

Juvenile and adult mussels of Lamprotula fibrosa which were reared from 1995 to October, 200l. The mussels were from collected from on-growing fish ponds of Aquatic Experimental Station in the Fisheries College, Huazhong Agricultural University and the ponds which are connected to Wanghu Lake, Yangxin,Hubei. 2085 mussels were collected by harrow. For identifying the age exactly, L. fibrosa were cultured for three years in those ponds where they were collected to validate that the mussels grow to one or two growth rings once a year. Before experiment, shell length was measured, gaps were sawed by saw blade and the last growth ring was marked. The steps were repeated for three years. The amounts of growth ring were gained according as the thickness and the convolve or protruding of the annular line in the shell exterior and they were observed by naked eyes and noted. The ages were confirmed by new growth rings in the shell exterior of L. fibrosa reared in the ponds for one year. From the vertical side of the shells, the shells of L. fibrosa were composed by shell layers of bright and dark. The bright layer and the dark layer consisted with the annular lines which have a group of hollow and protuberant in the shell exterior respectively. It is the annual rings. Observing the growth rings in the shell exterior through naked eyes, the annual lines in shell exterior which are thick and hollow are the growth rings or annual rings. Those thin and protuberant lines are annual growth lines and not growth rings or annual rings. This can be validated by the amounts of the layers which have bright and dark lines in the vertical side of the shell. The ages of L. fibrosa can be identified effectively through the growth rings of the colony layer and the pearl layer after the keratode layer or colony layer were wore away by grinding wheel. L. fibrosa increased one growth ring once a year. The structure analyze shows that L. fibrosa in Wanghu Lake were 29 age groups. The proportion of 7—10 ages is 33.48% and that of 1—15 ages is 46.09%. Their shel1weight accounts for 22.34% and 48.53% of whole shell weight, respectively. Their body weight accounts for 22.69% and 47.40% of Who1e body weight, respectively. L. fibrosa of 7—15ages covers most capture of those in Wanghu Lake. Dominant shell length is 7.15—10.64cm. Dominant shell weight is 99.40—160.62g. Dominant body weight is 126.04—276.09g. Annual ring can be identified by observing the sunken growth rings on the shell surface by eyes, and annual ring can be verified by observing the shell layers in shade and light check after opening shell longitude inner section and by observing growth rings in the prismatic layer and the pearl layer after polishing the shell. Before 10 ages,L. fibrosa grows faster than it does after 10 ages. Before 10 ages, the relations between age (A) and shell length (L) is linear correlated. The relationships between age (A) and shell weight (WS), body weight (W) all are power function correlated. The equations of regression before10 ages respectively are: L=0.8600+0.8980A (r=0.9883) WS=1.0175A 2.3399(r=0.9997) W=1.3188A2.3333(r=0.9997). After 10 ages, the relationship between age and shell length, shell weight, body weight are linear correlated. The equations after 10 ages are: L=7.9085+0.1817A(r=0.9813) WS=61.1930+10.7720A(r=0.9902) W=78.8690+13.6960A(r=0.9903). The relationship between shell length and shell weight, body weight are power function correlated. The correlative equations are: WS=0.6303L2.4846(r=0.9999) W=0.8181L2.4775(r=0.9999) The shell weight is linearly related to body weight, and the equation is:W=0.3560+1.2744WS(r=0.9999).