日本刺沙蚕大规模移植的生态学研究

LARGE SCALE TRANSPLANT OF THE NEANTHES JAPONICA (IZUKA) POPULATION

1991年11月—1992年5月在文登市高岛盐场总面积1665亩的30个虾池进行了日本刺沙蚕的移植研究,沙蚕的总投放量为1849/kg,每亩平均11.11kg。3月中旬测得的幼虫平均密度为20130个/m^3,4月中旬测得的定着幼虫和幼体的平均密度为3352个/m^2。对两次6组随机抽样总计1215条成体沙蚕测得的雌雄比为1:2。成熟雌体的平均怀卵量为24×10~4(±3.6×10~4)个,平均粒径为209(±3.7)μm。在移植沙蚕的虾池中,沙蚕幼虫定着的数量和生长发育的情况同自然纳潮虾池中的情况无任何差异。提出了两个简易的公式,以便计算对虾生长盛期为保持一定数量的沙蚕密度每亩所需投放的沙蚕数量。

In a Nov. 1991-May 1992 study on the transplant of Neanthes japonica (Izuka) 19 491 kg nereids were put in prawn ponds (in Wuleidao Bay in the Yellow Sea) at an average density of 11.11 wg/mu (one mu = 0.0667 hectare. The mean density of embryos, throchophora and necto-chaetes was 20 130 ind.Im3 in the middle of march; that of settled nectochaetes and juveniles was 3.352 ind./m2 in the middle of April. The ratio of females to males among the total of 1 215 adult nereids was 1:2. The average number of eggs produced by one moderately matured female was 24×104. The mean diameter of eggs during the spawning season was 209±3.7 μm. The nereids/mu put into the prawn ponds is obtained by the equation:M = G/g·W/rwhere, M is the total number of nereids (unit:g) putting into the grawn ponds in one mu during the transplant; G = 667 D/A, total numbers of eggs produced by females, D is expected density of nereids in August, 'A' is a product of a series of parameters, including the fertilization rate, survival rate at different stages and predation rate, A = 1.68×10-5 in the present study; g is the average number of eggs produced by one adult female nereid; W is the mean weight for one adult nereid and r represents the percentage of females.