洱海西太公鱼和太湖新银鱼生长特性及种群调控效果研究

Growth Characteristics and Population Regulation of Hypomesus nipponensis and Neosalanx taihuensis in Erhai Lake

洱海先后人为引入太湖新银鱼(Neosalanx taihuensis)和西太公鱼(Hypomesus nipponensis),其生长速度快、繁殖率高的生物学特性已对洱海生态环境造成影响,通过捕捞调控可降低其生物量。为了掌握其生长特性,评估人工调控效果,2017年1月至2018年12月在洱海采集2种鱼标本,通过测量体长与体重数据,对种群参数(L_(∞)、W_(∞)、k、t_(0)、Z、M、E)进行估算,并调查分析其年产量变化。结果显示:(1)西太公鱼和太湖新银鱼体长与体重关系回归参数b值分别为3.2148和2.8770,均属于等速生长。西太公鱼von Bertalanffy生长方程为L_(t)=13.65[1-e^(-1.80(t+0.17))],W_(t)=28.09[1-e^(-1.80(t+0.17))]^(3.2148),生长拐点年龄为0.48,相应体重为8.51 g,体长为9.41 cm;太湖新银鱼生长方程为Lt=9.45[1-e^(-0.92(t+0.38))],W_(t)=2.69[1-e^(-0.92(t+0.38))]^(2.8770),生长拐点年龄为0.75龄,相应体重为0.78 g,体长为6.11 cm。(2)西太公鱼总死亡系数、自然死亡系数、捕捞死亡系数和开发率分别为10.20、2.56、7.64和0.75,太湖新银鱼为4.66、1.84、2.82和0.61。(3)西太公鱼资源量2015-2018年呈逐年递增,但上升幅度逐年降低,而太湖新银鱼资源量2015-2018年逐年降低。研究表明,洱海西太公鱼和太湖新银鱼个体发育正常,生长周期相差一个月左右,西太公鱼的生长速度高于太湖新银鱼,人工调控取得了良好的效果。

For the economic benefit,Hypomesus nipponensis and Neosalanx taihuensis were introduced into Erhai Lake,but at different times.However,the fast growth and high reproduction rate of the two fish populations produced negative impacts on the ecology of Erhai Lake.So,the management departments of Erhai Lake used fishing to regulate their biomass,consequently increasing zooplankton density and improving water quality.In this study,we explored the growth characteristics of the H.nipponensis and N.taihuensis in Erhai Lake and evaluated the effects of population regulation based on the variation in annual yields of the two populations.The aim was to provide theoretical evidence for further ecological management.H.nipponensis and N.taihuensis samples were collected from January 2017 to December 2018 in Erhai Lake.The population parameters(L_(∞),W_(∞),k,t_(0),Z,M,E)were estimated based on the measurements of the body length and weight,and the changes in fishery yield were analyzed.Results show that:(1)The ranges of body length and body weight of H.nipponensis and N.taihuensis were,respectively,1.90-13.30 cm,2.00-9.20 cm and 0.04-25.34 g,0.04-2.63 g.The regression coefficient slopes(b)of the body length-weight relationship for H.nipponensis and N.taihuensis were 3.2148 and 2.8274,respectively,both displaying isometric growth.The von Bertalanffy growth equations for H.nipponensis were,L_(t)=13.65[1-e^(-1.80(t+0.17))]and W_(t)=28.09[1-e^(-1.80(t+0.17))]^(3.2148),and the growth inflection point age was 0.48 yr,with a corresponding weight of 8.51g and body length of 9.41cm.The von Bertalanffy growth equations for N.taihuensis were,L_(t)=9.45[1-e^(-0.92(t+0.38))]and W_(t)=2.69[1-e^(-0.92(t+0.38))]^(2.8274),and the growth inflection point age was 0.75,with a corresponding weight of 0.78g and body length of 6.11cm.(2)The total mortality coefficient,natural mortality coefficient,fishing mortality coefficient and exploitation rate of H.nipponensis and N.taihuensis were,respectively,10.20 and 4.66,2.56 and 1.84,7.64 and 2.82,0.75 and 0.61.(3)From 2015 to 2018,the H.nipponensis population increased each year from 2015 to 2018,but at a declining rate,while the N.taihuensis decreased each year.This indicates that ontogenetic development of H.nipponensis and N.taihuensis are normal in Erhai Lake,and the growth cycle of the two species is approximately one month.The growth rate of the H.nipponensis was higher than that of the N.taihuensis,and the goal of regulating their populations has been achieved.