沅水银鮈年龄与生长的研究

基于2016年3月至2017年3月采自沅水支流無水的137尾样本,使用耳石和鳞片为年龄鉴定材料,对银鮈(Squalidus argentatus)的年龄结构和生长特征进行了研究。结果显示:研究样本体长范围为40~115 mm,优势体长组为60~100 mm(占86.1%);体重范围为1.1~23.6 g,优势体重组为3~12 g(占77.4%);共4个年龄组,1龄和2龄为优势年龄组(占93.2%)。体长和耳石半径为直线正相关,L=-9.062+258.896×R(n=132,r2=0.773);体长-体重关系方程为:W=8.557×10~(-6)×L3.134(r2=0.974,n=137),银鮈为异速生长鱼类;以退算体长拟合的von Bertalanffy方程为:Lt=177.7(1-e-0.235(t+0.193))(r2=0.909),Wt=96.1(1-e-0.235(t+0.193))3.13。估算的拐点年龄为4.7龄,对应的体长体重分别为120.9 mm和28.7 g。研究表明耳石是银鮈较好的年龄鉴定材料。沅江银鮈的年龄结构趋于简单,面临较大的捕捞压力,渔业主管部门应为保护其种质资源制定相应的措施。

Age and growth of Squalidus argentatus in Yuanjiang River

Squalidus argentatus is a kind of small-sized fish which widely distributed in Chinese waters.In order to explore the age structure and growth characteristics of S.argentatus,a total of 137 samples were collected from the Yuanjiang River from March 2016 to March 2017.The ages were determined using scales and otoliths respectively.The stock of S.argentatus has a relatively simple age structure which contains 4 age classes ranging from 1 to 4.The dominant age classes were 1-2 years old accounting for 93.2％ of the total samples and standard length range was 40-115 mm,mainly between 60 mm and 100 mm(86.1％).The weight range was 1.1 ～23.6 g,mainly between 3 g and 12 g(77.4％).There was a positive linear correlation between standard length (L) and otolithsradius (R),which could be expressed as L =-9.062 + 258.896 × R(n =132,r2 =0.773).The relationship between standard L and W was power exponent and could be expressed as W =8.557 × 10-6 × L3.134 (r2 =0.974,n =137),which meant growth type was allometry.Von Bertalanffy growth functions were Lt =177.7 (1-e-0.235(t + 0.193)) and Wt =96.1 (1-e-0.235(t +0.193)) 3.13.The growth inflexion point was 4.7 years and the corresponding standard length and weight were 120.9 mm and 28.7 g respectively.The results showed that sectioned lapillus was a better ageing material of the fish.Now the age structure of S.argentatus stock was simple,some measures should be taken to protect this fish and reduce the fishing efforts.