管角螺幼螺网笼吊养技术初探

分别采用不同网笼养殖密度和海区网笼吊养的方法，对管角螺进行养殖试验，结果表明：经过60d的不同养殖密度养殖，各密度组幼螺壳高、体质量的生长均呈指数生长，除10个·笼-1密度组生长离散（SV）增加外，其他4个密度组（20，30，40，50个·笼-1）生长离散（SV）均降低；不同密度组间生长表现差异显著，20，30个·笼-1密度组的生长速度最快；生长率、特定生长率和日增质量都随密度的增大而降低，特定生长率与养殖密度存在着显著的3次项回归关系（SGR=0．8573＋0．1532D-0．0051D2＋0．00005D3，R2=0．9991）。海区网笼吊养结果表明：选取养殖密度为30个·笼-1，经过100d的海区吊养，管角螺壳高增加了34．7％，体质量增加了157．4％，壳高平均日增长0．18mm，体质量平均日增长0．173g，成活率为98％；网笼吊养模式适合管角螺养殖。

Suspended net cage culture of juvenile Hemifusus tuba

Juvenile Hemifusus tuba were net cage cultured at different stocking densities （10, 20, 30, 40, 50 shells/cage） to select optimum stocking density and then cultured in suspended net cages in Yunbo bay, Yangjiang city, Guangdong Province. The juvenile H. tuba reared under different stock densities for 60 days in natural conditions showed an exponential growth in shell height and body weight. The coefficients of variance （CVs） for the growth of the juvenile H. tuba in all the treatments except D1 （ 10 juveniles/cage） were significantly reduced. The juvenile H. tuba grew significantly different among the all the treatments, but fastest in the treatments D2 （20 juveniles/cage） and D3 （30 juveniles/cage）. The growth rate, specific growth rate （SGR） and daily weight growth （DWG） of the juvenile H. tuba decreased with the increase of the stocking densities. The SGR had a significant cubic polynomial regression with the stocking density （SGR = 0. 857 3 ＋ 0. 153 2D - 0. 005 1D2 ＋0. 000 05D3, R2 =0. 9991 ）. Juvenile H. tuba in the treatments D2and D3 grew the fastest in all stocking densities, but the D3 （30 juveniles/cage） was the optimum stocking density and selected for net cage culture when the rearing cost and management were considered. The juvenile H. tuba were cultured in suspended net cages at the stocking density of 30 juveniles/cage in Yunbo bay. After 100 days of suspended net cage cul- ture of the juveniles, the shell height increased by 34.7%, and body weight by 157.4%. The DWG and daily height growth （DHG） were 0.18 mm · d and 0. 173 g ·d, respectively. The survival rate was 98%. The suspended net cage culture is found fit for culture of juvenile H. tuba.