甬江溪口段宽鳍鱲的种群结构及繁殖力初步研究

Population Structure and Fecundity of Zacco platypus in the Xikou Section of Yongjiang River

利用鱼类种群调研法,于2015年8月至2016年4月在甬江溪口段收集宽鳍鱲(Zacco platypus)个体样本,研究该区域宽鳍鱲种群的年龄组成、性比、个体大小以及繁殖力等种群结构生物学特征。结果表明:(1)调查期间甬江溪口段宽鳍鱲种群由3个年龄组组成,其中2龄为优势年龄组;雄性个体中2龄组占雄体总数的55.5%,雌性个体中的2龄组占雌体总数的63%;(2)宽鳍鱲全长(L)的分布区间为7.0～14.0 cm,8.0～12.0 cm的个体占总数的87.83%;(3)体重(W)分布范围为4.0～36.0 g,其中体重5.0～13.0 g的个体占总个体数的72.75%;(4)根据不同性别(性别难辨、雌、雄、群体)拟合体重与体长的幂函数关系式:W_(ui)=1×10^(-4)L^(2.4917)、W_♀=2×10^(-5)L^(2.9337)、W_♂=3×10^(-5)L^(2.8471)和W=4×10^(-5)L^(2.8035);(5)雌雄个体比例127∶238与理论值1∶1存在极显著差异(P<0.01);(6)重量法计数得出种群个体的绝对繁殖力平均值为(2 850.39±2 107.49)粒,分布区间为532.00～13 717.89粒,其中1 000～3 000粒占绝对优势(65.12%);个体体长相对繁殖力为(354.39±234.47)粒/cm,分布区间74.93～1 541.34粒/cm;体重相对繁殖力平均值为(363.73±178.55)粒/g,分布区间为91.25～1 027.56粒/g;比较了国内外不同地区间宽鳍鱲种群结构和繁殖力的异同。

Zacco platypus is an important economic species in the Yongjiang River,Zhejiang Province.However,there are few reports on the biological characteristics and population structure of Z.platypus.This article analyzes the population structure of Z.platypus in the Xikou section of Yongjiang River,focusing on age composition,sex ratio,body volume and fecundity and compares the structures of Z.platypus population from different areas.The study will supplement the biological baseline of the natural Z.platypus population and provide reference for the conservation and reasonable exploration of the natural Z.platypus germplasm resources.A total of 411 Z.platypus specimens were collected in the Xikou section of Yongjiang River from August 2015 to April 2016.The total length,body length and weight of the specimens were measured in situ,scales and gonads were collected for age and sex identification,and 43 female Z.platypus with ovaries at stage IV were selected for determination of fecundity.Results show that:(1)The Z.platypus population was composed of three age groups,dominated by 2-year-olds that accounted for 55.5%of the males and 63%of females.(2)The range of body length(L)was 7.0-14.0 cm and the group 8.0-12.0 cm accounted for 87.83%.(3)The range of body weight(W)was 4.0-36.0 g and the group 5.0-13.0 g accounted for 72.75%.(4)The body length-weight relationship for different groups were as follows:Wui=1×10-4L2.4917,W♀=2×10-5L2.9337,W♂=3×10-5L2.8471 and W=4×10-5L2.8035.(5)The female-male ratio was 127∶238,significantly different from the theoretical ratio 1∶1 according to the chi-square test(P<0.01).(6)The range in absolute fecundity(gravimetric method)was 532-13 717.89 eggs,with an average value of(2 850.39±2 107.49)eggs and the group with fecundity of 1 000-3 000 eggs was dominant(65.12%).The range for relative fecundity by weight was 91.25-1 027.56 eggs/g and,by length,74.93-1 541.34 eggs/cm,with average values of(363.73±178.55)eggs/g and(354.39±234.47)eggs/cm.The age composition and sex ratio of the Z.platypus population in Yongjiang River were in good agreement with those of Z.platypus populations in and out of China.