中国南海黄鳍金枪鱼(Thunnus albacares)幼鱼形态特征及其与体重的关系

Morphological Characteristics and Their Relationships With the Body Weight of Wild Juvenile Thunnus albacares

为研究出现在中国南海美济礁的黄鳍金枪鱼(Thunnus albacares)幼鱼的形态特征及其各性状特性与体重的关系,对其附近海域捕捞的52尾野生黄鳍金枪鱼幼鱼的外部形态特征进行观察分析,并对其全长、体长、头长、体高、头高、眼径、眼间距、口裂、吻长、尾柄长、尾柄高和体重12个可量性状进行测量。通过相关分析、通径分析和决定分析方法,分析各形态性状对体重的影响程度,运用多元线性回归分析法建立主要性状对体重的多元回归方程。结果显示,鱼体呈纺锤形,粗壮而圆,向后逐渐细尖,尾柄细长,背部较暗,呈深蓝色,腹部银白色,体表具有浅银灰色间隔的纵向条纹,并有明亮的光泽,尾鳍末端呈黄褐色;体长、体高和尾柄高与体重的相关性达到极显著水平(P<0.01),是影响体重的主要性状。体长对体重的通径系数最大(0.479)、决定系数最高(0.229),体长、体高主要通过直接作用对体重产生影响,而尾柄高主要通过体高、体长对体重起间接作用;以体重为因变量(y),体高(x_1)、体长(x_2)、尾柄高(x_3)为自变量,得到估算体重的最优多元回归方程为y=30.482 x_1+18.328 x_2+199.490 x_3-500.785。

Yellowfin tuna is a marine fish species with high economic value. In this study we identified the morphological characteristics of yellowfin tuna and investigated the correlation between their morphological traits and body weight. Fifty-two wild larval yellowfin tuna were sampled from Sansha mischief reef in the South China Sea, and twelve external morphological characteristics were measured and analyzed including the total length, body length, head length, body height, head height, eye diameter, interorbital width, mouth breadth, snout length, tail handle length, tail handle height and body weight. The correlation between those traits and the body weight was explored with a variety of methods such as correlation analysis, path analysis and decision analysis methods. We also used multivariate linear regression analysis to establish a multivariate regression equation for the body weight. The typical morphological traits were described below： think spindle body shape with a rounded cross section, tapering ends, slender tail handle, dark blue back, silver abdomen, silver gray stripes on the surface, bright luster, and yellow brown end of the tail fin. There was a significant correlation between the body weight and other traits such as the body length, body height, and the height of the tail handle （P〈0.01）. The body length had the major direct effect （0.479） and determinacy （0.229） on the body weight. Body length and body height had strong direct effects on the body weight, while the height of the tail handle only had indirect effects. The multiple regression equation for the body weight was y = 30.482 x1 ＋ 18.328 x2 ＋ 199.490 x3 - 500.785, where y was body weight, and x1, x2, x3 were body height, body length and tail handle height respectively.