西北印度洋公海鸢乌贼的繁殖生物学及其与环境要素的关系

Reproductive biology of purpleback flying squid in the Northwestern Indian Ocean and its relationship with environmental factors

摘要:

为了分析印度洋鸢乌贼（Sthenoteuthis oualaniensis）群体结构和组成的年际变化及其主要环境影响因素,在2019年12月—2020年2月以及2020年9—11月连续2个航次在西北印度洋公海海域（60°E~65°E,15°N~20°N）开展了生产性渔业调查。在调查中,采集了印度洋鸢乌贼样本1 430尾,共鉴定性别748尾,鉴定雌雄总性比为1∶0.97。利用SPSS统计软件等方法,分析了鸢乌贼的胴长、体质量、性别、性成熟度和摄食强度等生物学特征。得出雌、雄个体的平均胴长分别为248和207 mm,优势胴长组为220~250 mm。鸢乌贼的胴长和体质量关系呈幂函数变化。通过Logistic曲线拟合鸢乌贼个体初次性成熟胴长,其中第一航次雌性个体为361 mm,雄性个体为171 mm；第二航次雌性个体为202 mm,雄性个体为153 mm。鸢乌贼性腺成熟度达到Ⅲ、Ⅳ和Ⅴ期（性成熟）的个体占比高达66.53%,雌性成熟群体占57.37%,雄性成熟群体达到75.20%。同时分析了鸢乌贼成熟群体与海洋环境因子的关系,推测其生长发育受海表面温度（Sea surface temperature,SST）、海表面温度距平值（Sea surface temperature anomaly,SSTA）、叶绿素a质量浓度（Chlorophyll-a mass concentration,Chl.a）等关键海洋环境因子的影响。此外,调查显示,2019年12月—2020年2月航次鸢乌贼性成熟群体比重较2020年9—11月航次高25.93%。以上结论为后期可持续开发利用西北印度洋海域鸢乌贼资源提供参考依据。

关键词:鸢乌贼;性腺成熟度;性比;年际变化;西北印度洋公海

Abstract:

In order to analyse the inter-annual variation in the population structure and composition of the purpleback flying squid （Sthenoteuthis oualaniensis） and its main environmental influences. A productive fishery survery was conducted on two consecutive cruises from December 2019-February 2020 and September-November 2020 in the open ocean waters of the northwestern Indian Ocean from 60°E to 65°E, 15°N to 20°N, to collect samples of the Indian Ocean purpleback flying squid was carried. During the survey, we obtained 1 430 purpleback flying squid samples, with a total of 748 sexes identified, and a total sex ratio of male to female of 1∶0.97.We analyzed the biological characteristics of the purpleback flying squid, like mantle length, body mass, sex, sexual maturity and feeding intensity, by means of the SPSS statistical software. The average mantle lengths of females and males were 248 mm and 207 mm, respectively, and the dominant mantle length group was 220-250 mm. The Logistic curve was employed to fit the mantle length at the first sexual maturity of the purpleback flying squid. During the first voyage, the mantle length at the first sexual maturity for female individuals reached 361 mm, while that for male individuals was 171 mm. In the second voyage, the mantle length at the first sexual maturity of female individuals measured 202 mm, and that of male individuals was 153 mm. The proportion of individuals with gonadal maturity stages Ⅲ, Ⅳ and Ⅴ （sexual maturity） was as high as 66.53 %, with 57.37 % of females and 75.20 % of males in the mature group. Meanwhile,by utilizing the marine environmental data acquired from remote sensing satellites, the relationship between the distribution of the proportion of mature groups of purpleback flying squid and the main environmental factors was analyzed. It was considered that their growth and development were influenced by crucial factors in the marine environment, namely sea surface temperature （SST）, sea surface temperature anomaly （SSTA）, chlorophyll-a mass concentration （Chl.a）, and so on.In addition, the survey showed that the proportion of sexually mature groups of purpleback flying squid was 25.93% higher in the December 2019-February 2020 cruise compared to the September-November 2020 cruise. The above conclusions provided a reference basis for the later sustainable development and utilization of purpleback flying squid resources in the northwestern Indian Ocean waters.

Key words:purpleback flying squid （Sthenoteuthis oualaniensis）;gonadal maturity;sex ratio;inter-annual variation;high seas of Northwestern Indian Ocean