南海鸢乌贼微型群雌性个体繁殖力研究

Characterizing Fecundity of Dwarf form of Female Purple Flying Squid (Sthenoteuthis oualaniensis) in the South China Sea

中文关键词: 鸢乌贼  繁殖力  微型群  多次产卵  南海

英文关键词: Sthenoteuthis oualaniensis  Fecundity  Dwarf form  Multiple spawning  South China Sea

中文摘要:

      根据2017年灯光罩网船在南海海域采集的鸢乌贼(Sthenoteuthis oualaniensis)微型群雌性样本，进行繁殖力特性的测定分析。结果显示，南海鸢乌贼微型群雌性个体潜在繁殖力为1218~32843 cell，卵巢卵母细胞数为1178~30397 cell，输卵管成熟卵子数为113~2904 cell。相对繁殖力为48.93~842.12 cell/g，总体潜在繁殖投入指数为0.005~0.213。潜在繁殖力与胴长呈幂函数关系，与体重呈线性相关关系。相对繁殖力与胴长呈指数函数关系，与体重呈线性相关关系。潜在繁殖投入指数与胴长和体重均呈线性相关关系。产卵繁殖期，雌性个体的分批繁殖力为1895~2904 cell，产卵批次为6~15，平均值为9.87±4.36。卵巢卵母细胞的卵径范围为0.17~0.99 mm，均值为(0.51±0.14) mm，不同性腺成熟度之间的卵径存在显著性差异(P<0.05)。Ⅲ~Ⅵ期的卵巢卵母细胞卵径大小均呈单峰值区间分布，随性腺发育峰值区间呈前移趋势，Ⅲ~Ⅳ期时峰值区间为0.35~0.60 mm，Ⅴ~Ⅵ期为0.40~0.75 mm。输卵管成熟卵子的卵径为0.50~ 1.08 mm。研究表明，南海鸢乌贼微型群雌性个体繁殖力随个体生长发育呈增长趋势，卵巢卵母细胞为批次发育成熟，产卵活动为分批次产卵。

英文摘要:

      Female specimens of the dwarf form of Sthenoteuthis oualaniensis, the purple flying squid, were collected from light-falling fishery catches from the South China Sea in 2017. The fecundity of this species was investigated and characterized. The results showed that the potential fecundity of female individuals ranged from 1218 to 32843 oocytes. The number of ovarian oocytes ranged from 1178 to 30397 cells, and the number of ripe eggs in the oviducts ranged from 113 to 2904 cells. In addition, the relative fecundity ranged from 48.93 to 842.12 cell/g of a female’s total weight, and the overall potential reproductive investment index varied from 0.005 to 0.213. The potential fecundity showed a significant power regression relationship to mantle length and linear relation to body weight. Relative fecundity showed a significant exponential relation to mantle length and linear correlation with body weight. Potential individual reproductive investment index increased linearly with increasing mantle length as well as body weight. Batch fecundity had an estimated range from 1895 to 2904 cells based on the number of ripe oocytes in the oviducts of late-maturing individuals (stage Ⅵ), and the number of spawn per batch was estimated to range from 6 to 15 with an average of 9.87±4.36. Major axis length of ovarian oocytes was measured and ranged from 0.17 to 0.99 mm with an average of (0.51±0.14) mm. There were significant differences in major axis length of ovarian oocytes among different maturity stages (P<0.05). The frequency of major axis length of oocytes in the ovary showed a unimodal distribution for specimens at stages Ⅲ to Ⅵ. Moreover, the frequency distribution peak showed a forward increase with maturation when the mode was between 0.35 and 0.60 mm for stages Ⅲ and Ⅳ, while it showed a forward increase when the mode was between 0.40 and 0.75 mm for stages Ⅴ and Ⅵ. The major axis length of ripe eggs in the oviducts ranged from 0.50 to 1.08 mm. Cumulatively, these findings indicate that fecundity of the dwarf form of female S. oualaniensis tends to increase as body size increases and as maturation progresses. Furthermore, the ovarian oocytes develop in a pattern of group-synchrony, and ovulation occurs multiple times.