Primary Studies On Conservation Biology Of Lamprotula Leai (Gray)

The conservation biology of Lamprotula Leai was studied in the Ganjiang River and Xiuhe River, Jiangxi province from Jan. 2004 to Mar. 2005. The results were summarized as follows.1. Several characteristics and parameters of shell, such as shell length, shell width, adductor scar, lateral teeth, pseudocardinal teeth, were analysised. Their correlation formulates are: W=0.2727 L+6.5596 (R² = 0.9419); H=0.3681 L+ 5.2278 (R²=0.9319); B-0.6093 L+1.4885 (R²=0.9871); C₁ = 0.4779 L-3.7448(R²=0.9115) , C₂=0.4999L-1.4458 (R²=0.8885) , C₃ = 0.4627 L+4.7394 (R² =0.8772) .The results showed that the order and position of strumaes were variable while other characteristics were relatively stable.2. By analyzing the age and the growth of this population, Maximum shell length of L. leai (101 millimeters) and the eldest individual (17 years) were found in the field population. The relationships between shell age and length, growth per year (AL) were logistic function correlated. The equations of regression were: L=30.558 Ln(A) +20.036 (R²=0.9939) , AL=-5.591 Ln(A)+16.157 (R² = 0.8828), respectively. The relationships between shell length and body weight, tissue weight were power function correlated. The equations of regression respectively were: W_b = 0.0006 L^2.6692 (R² =0.9354), W_t = 0.0001 L^2.5588 (R² = 0.9541). The fatnesses of L. leaireached the maximum value in February (0.103±0.020) while the minimum value in July (0.135±0.026).3. The population structure of L. Leai showed that the distribution of shell length classes tended to be younger and smaller, while the shell length of 41-70mm and the age of 3-6 years accounted for 74.93% and 60% of the population respectively.4. The reproduction characteristics were studied, the results showed that L. leai were dioecious, and the sexual ratio of females to males was about 1:1. Gametogenesis occurred throughout the year and the gonad development could be divided into 4 phases: a multiplication phase from June to October; a growth phase form November to February in next year; a maturation phase from February to April; a post-spawned phase from April to June. Gravid individuals were very sensitive to the changing of the environment, and they would abort by water temperature changing sharply or catching rudely. Four demibranchia of the gills of females could develop into marsupium; Mature glochidia are non-hooked with 4 aesthetasc. The reproductive potential which was 115,000-504,000 per individual (the average value was 328,090±145,730 per individual), was somewhat correlated with shell length.5. The density and biomass of L. leai in Wucheng area of Gan River have been investigated. Mean density (0.02 ind·m²) and mean biomass (1.38 g·m²) weremeasured. Also, it was found that the density and biomass were influenced by substrate, velocity of flow, the sand-mining and illegal fishing.