基于精荚数量对鸢乌贼中型群雄性个体有效繁殖力的研究

Study on the Effective Fecundity in Medium Form of Male Purple Flying Squid Sthenoteuthis oualaniensis in the South China Sea

根据2017年和2018年在我国南海海域采集到的鸢乌贼(Sthenoteuthis oualaniensis)中型群雄性样本,利用生物统计分析和线性模型拟合等方法研究其有效繁殖力特性及其在性腺发育过程中的变化规律。结果表明,南海鸢乌贼中型群雄性胴长分布范围为114~153 mm,体重分布范围为55.2~174.7 g。个体精荚囊的长度为22~124 mm,精荚囊重量为0.03~3.07 g,两者呈幂函数关系,且均随着性腺发育而逐步增大。精荚囊长度及其重量与胴长和体重均呈线性函数关系。精荚囊长度及其重量均在性腺成熟度Ⅵ期时达到最大值,分别为(94.33±21.64)mm和(1.57±1.07)g。有效繁殖力为1~144条,胴长相对有效繁殖力为0.02~1.62 条/mm。随着个体生长发育,有效繁殖力在Ⅵ期达到最大值,相对有效繁殖力则在Ⅵ~Ⅶ期时趋于稳定。有效繁殖力与胴长、体重均呈线性函数关系,相对有效繁殖力与胴长、体重均呈幂函数关系。精荚长度为4.79~36.60 mm,精荚重量为0.000 2~0.020 0 g,两者符合幂函数关系,且均在Ⅵ期达到最大值。同时,精荚长度及其重量与胴长、体重均呈线性函数关系。研究表明,南海鸢乌贼中型群雄性个体的精荚囊、精荚和有效繁殖力均随着性腺发育而不断增大,且三者均与个体胴长、体重呈显著的函数关系。

Purple Flying Squid (Sthenoteuthis oualaniensis) is one of the most important tropical Ommatrephids,widely distributing in the tropical waters of Indo-Pacific,but little information is available on its fecundity,particularly for those populations living around South China Sea.From 28 specimens of S.oualaniensis collected in 2017 and 2018 in the South China Sea,effective fecundity and its variations with sexual maturation were assessed using bio-statistical and model fitting analysis.The specimens were measured 114﹣153 mm in mantle length,and weighed from 55.2 to 174.7 g (Table 1).The length and weight of spermatophoric sac increased with sexual maturation measured 22﹣124 mm in length and 0.03﹣3.07 g in weight,respectively (Table 2).The spermatophoric sac’s weight showed a power regression on its length.In addition,both the length and weight of spermatophoric sac were linearly correlated with mantle length and body weight (Fig.2,3).The effective fecundity was estimated from 1 spermatophores at stage Ⅲ to 144 spermatophores at stage Ⅶ,and the relative effective fecundity by mantle length was estimated from 0.02 to 1.62 spermatophores per millimeter.The effective fecundity increased with maturity and reached to the highest value at stage Ⅵ and remained stable till stage Ⅶ.The effective fecundity showed a linear relationship with mantle length and body weight (Fig.4),while the relative effective fecundity by mantle length had a power regression on mantle length and body weight (Fig.4).The spermatophore length was a power function of its weight,in which they were measured from 4.79 to 36.60 mm in length and from 0.000 2 to 0.020 0 g in weitht,respectively (Table 3).Both the length and weight of spermatophores attained their highest value at stage Ⅵ,and in addition,both of them were found linear correlation with mantle length and body weight (Fig.6).These findings indicated that the spermatophoric sac,spermatophores and effective fecundity in the medium form of male S.oualaniensis from South China Sea showed a consistent increasing trend with sexual maturation,and significantly related to mantle length and body weight.