厦门杏林湾鲻鱼年龄和生长的研究

AGE AND GROWTH OF THE STRIPED MULLET IN XINGLIN WAN OF XIAMEN

厦门杏林湾鲻鱼鳞片年轮可作为年龄鉴定依据。鳞片边缘增长率α的周年变化,表明鳞片年轮每年形成一次,新年轮主要在10—11月间出现。已计算出鲻鱼体长与鳞长、体长与体重的关系式。3龄鱼以前属于幼鱼生长阶段,体长和体重的相对增长率较大,生长指标较高;3龄鱼以后则进入成鱼生长阶段。其生长适合于von Bertalanffy生长方程,体重生长曲线的拐点位于2龄至2.5龄之间,其生长速度和加速度曲线能反映生长过程的变化特征,合理捕捞的生物学指标应以生长转折点较为适当,限制捕捞1龄和2龄的港养鲻鱼是提高单位面积产量的关键之一。

The scales of the striped mullet, Mugil cephalus Linnaeus, used for age de-termination were collected from Xinglin Wan of Xiamen, a brackish water bayinclosed by dam, during the period from September 1961 to October 1962. Thedistinction between the true annulus and the false annulus has been described. It isconfirmed that breaks were formed annually, dividing the scale into zones whosedimensions were related to tbe growth of the striped mullet. New annuli began toappear mostly in the months of October and November. The striped mullet matures at3 years old and the growth rates decreased after the adult stage. The length--weight relationship formula was calculated to be W= 6.492×10^(-5)L^(2.7768), the relationship between the scale length and standard length was expressed tobe R= 0.031 L-0.8359, where W, L and R represent body weight (excluding gutand gonads) in grams, standard length in mm and scale length in mm respectively. Itwas found that the growth of the striped mullet in Xinglin Wan corresponds to vonBertalanffy's growth equation, then we obtain W_t = 4864(1 - e^(-0.818(t+1.171))~a, L_t = 685. 1 (1-e^(-0.818(t+1.171)).Here W_t is body weight (excluding gut and gonads) in grams at the age of t, and L_t isstandard length in mm at the age of t. In order to increase the production of thestriped mullet in Xinglin Wan, it is necessry to prohibit the capture of young fish,suggested minimum legal harvestable age and size of this fish may be 2.5 years old,450mm in length and 1500 grams in weight.