东太平洋赤道海域茎柔鱼主要生物学特性比较研究

A comparative study of the main biological characteristics of jumbo flying squid(Dosidicus gigas) in the waters near the equator of the eastern Pacific Ocean

根据中国远洋鱿钓船于2018年2-4月在东太平洋赤道(110°W^114°W、2°40’S^2°N)作业期间现场取样的1200尾茎柔鱼(Dosidicusgigas)样本进行研究,利用频率分布法分析了2-4月胴长、体重、性腺成熟度和摄食等级的分布,并通过拟合求出了胴长-体重的关系和初次性成熟胴长。根据采样海域的遥感温度,讨论了茎柔鱼不同月份雌雄个体生长的差异。结果显示,2-4月雄性茎柔鱼优势胴长依次为26~28 cm(19.33%)、30~32 cm(26.46%)、28~30 cm(31.82%),雌性分别为24~26 cm(16.8%)、28~30 cm(24.95%)、26~28 cm(21.79%);2-4月雌雄茎柔鱼优势体重均依次为400~600 g(28%、20.67%)、600~800 g(29.14%、28.25%)、600~800 g(25.64%、31.82%)。协方差表明3月雌性茎柔鱼与同月雄性茎柔鱼以及2月、4月的雌性茎柔鱼生长模式均存在显著性差异(P3<0.01,P2-3<0.01,P3-4<0.05)。2-4月雌、雄性茎柔鱼摄食等级均以1~2级为主,高摄食等级占比逐月降低。雄性茎柔鱼性腺发育均以Ⅱ期为主,性成熟比例逐月升高,初次性成熟胴长为32.72cm;雌性性腺发育缓慢,各月发育均以Ⅰ期为主,未成熟比例占97%以上,茎柔鱼胴长和体重随性腺等级的提高呈逐级增长状态。综合判断雄性茎柔鱼性成熟比雌性早,性成熟雄性个体或因交配正在离开赤道海域开始向美洲沿岸洄游。

The aim of this study was to obtain the most recent data and investigate the biological characteristics under a changing environment for jumbo flying squid, Dosidicus gigas. This study involved 1200 samples of D.gigas collected by a Chinese squid jigging vessel from February to April 2018 in the eastern equatorial Pacific Ocean(110°W-114°W, 2°40’S-2°N). The distribution of mantle length(ML), body weight(BW), maturity stages,and stomach stages from February to April was studied using the frequency distribution method. The relationship between ML to BW and the first mature ML was obtained by best power exponent fit. The differences in the growth of female and male squids among different months were discussed based on the remote sensing temperature that was dependent on sampling location. Ranges of ML and BW of female squid were 20-46.7 cm and240-3420 g, respectively, and averages were(30.6±4.47) cm and(939.07±460.02) g, respectively, whereas for males, ranges of ML and BW were 22.2-42.5 cm and 310-2270 g, and the averages were(31.3±3.93) cm and(925.57±358.6) g, respectively. The dominate ML of males in February, March, and April was 26-28 cm, 30-32 cm, and 28-30 cm, whereas females were 24-26 cm, 28-30 cm, and 26-28 cm, respectively. The dominate BW of males and females in February, March, and April was 400-600 g, 600-800 g, and 600-800 g, respectively. The equation of the relationship between ML and BW was fitted with the power exponent. The effect of sex on the exponent "b" of the BW-ML relationship was significant in March, thus there was a significant difference in body growth between female and male individuals as revealed the analysis of covariance(P3<0.01). There were also significant differences in body growth among the three months for the same sex(P2-3<0.01 and P3-4<0.05). From February to April, the stomach stages of males and females were mainly 1 to 2 with the ratio of higher stomach stages decreasing with each month. The sexual ratio of females to males was 2.04 : 1. The maturity stages of males were mainly Ⅱ with the ratio of maturity stage increasing with each month. The ML at first maturity of males was32.72 cm. The maturity stages of females were mainly Ⅰ with the ratio of the immature stage accounting for greater than 97%. A linear relation was found for ML and BW and maturity stages for both male and female squid. From February to March was a period of rapid growth and development, especially for males. However, in April, the dominant group no longer grew. Thus, the maturity stages of males develop earlier than the maturity stages of females, and the mature males leave the equatorial waters and begin to migrate.