南海黄鳍金枪鱼(Thunnus albacores)摄食习性及其随生长发育的变化

Feeding Habits and Ontogenetic Diet Shifts of Yellowfin Tuna(Thunnus albacores) in the South China Sea

基于2012–2013年在我国南海水域调查获得的黄鳍金枪鱼(Thunnus albacores)生物学基础性数据,利用传统胃含物分析方法并结合碳、氮稳定同位素技术对黄鳍金枪鱼摄食习性进行了研究。结果显示,南海黄鳍金枪鱼食物组成包括鸢乌贼(Sthenoteuthis oualaniensis)、枪乌贼属(Uroteuthis)、乌贼属(Sepia)、圆鲹属(Decapterus)、蛇鲭属(Gempylus)、帆蜥鱼(Alepisaurus ferox)、日本乌鲂(Brama japonica)、燕鳐属(Cypselurus)、甲壳类动物及不可辨别鱼类等饵料类群,其中,鸢乌贼(IRI=51.07%)、圆鲹属(IRI=39.81%)及不可辨别鱼类(IRI=6.62%)为主要饵料食物。黄鳍金枪鱼的空胃率、平均饱满指数和食物组成都有明显的月变化(P<0.05)。空胃率随叉长组变化呈较明显的上升趋势,各叉长组之间空胃率变化显著(P<0.05);平均饱满指数随叉长变化较大。当叉长组为130–160 cm时,ShannonWeiner多样性指数H?在0.50–1.18之间变化,Pielou均匀度指数J在0.10–0.32之间。基于氮稳定同位素计算的黄鳍金枪鱼各叉长组的平均营养级为3.54。

To understand the diet composition of wild yellowfin tuna （Thunnus albacores） and its ontogenetic variations, some surveys were conducted from February 2012 to January 2013 in the South China Sea. Both stomach content and stable isotope analysis were used to study the feeding ecology of yellowfin tuna. A total of 94 yellowfin tuna samples, ranging between 41 cm and 180 cm in fork length （FL）, were measured according to the national standards on specifications for oceanographic survey （GB/T 12763.6-2007）. Results showed that diet compositions of Thunnus albacores mainly consisted of Sthenoteuthis oualaniensis, Uroteuthis sp., Sepia sp., Decapterus sp., Gempylus, Alepisaurus, Brama japonica, Cypselurus sp., unidentified crustacean and fishes, etc. S. oualaniensis was the primary prey components of the diet, averaging 51.07% by percentage of Index of Relative Importance （IRI%）. Decapterus was the second most important diet, with IRI of 39.81%. The percentage of empty stomach, mean stomach fullness index and diet compositions had significant monthly variation （P〈0.05）. The vacuity coefficient changed significantly in each group of FL and showed the upward trend （P〈0.05）. Mean stomach fullness index had significant monthly variation. With the group between 130 and 160 cm FL, Shannon-Weiner diversity index/-f ranged between 0.05 to 1.18 and Pielou evenness index J varied from 0.10 to 0.32. The average trophic level of yellowfin tuna in the South China Sea was 3.54. In conclusion, the results improved the understanding of the yellowfin tuna biological characteristics and feeding habits, also provided some empirical data for marine ecosystem modeling in the South China Sea.