Studies On Age And Growth Characteristics And Reproductive Biology Of Schizopygopsis Malacanthus Chengi In Chuosijia River

During May,2010to May,2011, we have collected518in dividuals of Schizopygopsis malacanthus chengi from Chuosijia River.Studied the age and growth characteristics,then calculated the annual population size,and I made some strategies and measures for the population protection and exploition of Schizopygopsis malacanthus chengi;In addition,we studied the reproduce biology of Schizopygopsis malacanthus chengi.The main results were summarized as follows:1. We identified the age of Schizopygopsis malacanthus chengi by the different age materials,and deemed sectioned lapillus was the more accurate age material.2. There were the complicated age configuration in the population of Schizopygopsis malacanthus chengi.The preponderant group were from4to6,taking58.5percent of the total;The average body length was12.56±3.72cm;The average weight was52.22±39.12g.3. The length-weight relationship can be expressed by the equation W♂=0.0245×L2.7934, W♀=0.0213×L2.8593;The relationship between body length and sectionged lapillus radius can be expressed by the equation L♂=100.53×R+2.6294(R2=0.8191, n=152); L♀=122.67×R+0.8789(R2=0.8363, n=169);The relationship between age and sectioned lapillus radius can be expressed by the equation N=0.0319Ln (R)+0.0642(R2=0.8817,n=212);The VBGF equation of the body length and weight was different between the male and the female,the VBGF equation of the male were Lt=23.195x [1-e-0.213×(t-1.008)](R2=0.925), Wt=169.3072x [1-e-0.213×(t-1.008)]2.7934,the VBGF equation of the female were:Lt=32.319×[1-e-0.087×(t+4.024)](R2=0.886), Wt=439.165×[1-e-0.087(t+4.024)]2.8593.The infexion point was different in the male and the female,the infexion point of male was6.0years,and the body length and weight were15.18cm and51.85g;the infexion point of female was8.1years,and the body length and weight were21.06cm and129.12g.4. The total mortality coefficient Z of Schizopygopsis malacanthus chengi in Chuosijia River was0.81,the total mortality rate A was0.56,the natural mortality coefficient M was0.35,the natural mortality rate V was0.24,the fishing mortality coefficient F was0.46,the fishing mortality rate U was0.32,the exploited rate E was0.58.The population biomass of Schizopygopsis malacanthus chengi in Chuosijia River was7803.77Kg by the LAC analysis.5. The breeding time of Schizopygopsis malacanthus chengi lasts from May to October,reaching the peak at June and August. Measuring the egg size of stage IV ovary,the result had two peaks,so the fish could spawn twice in a reproductive period,and the quantity of mature ovum for the second batch was greatly less than the first batch.6. The minimum body length of mature male was11.3cm with the body weight of22.3g at2years old.The minimum body length of mature female was14.8cm with the body weight of46.3g at4years old.7. The sex ratio of Schizopygopsis malacanthus chengi was1.11:1during the period of reproduction(N=321),the result showed the number of female was moer than the male.Compared to the different body length groups,when the body length was less than16cm,the number of male was greatly more than the female in the population;when the body length was more than16cm,the number of the male was greatly less than the female.8. The absolute fecundity was2110to3431eggs,the relative fecundity was103.46to146.04eggs/cm or23.58to35.37eggs/g.The absolute fecundity of Schizopygopsis malacanthus chengi went up along with body length、body weight and gutted weight.9. The number of the first mature individual was preponderant in the spawning population,so the spawning type was Ⅱ,that the primarily group was the supplement.10.The spawning conditions of Schizopygopsis malacanthus chengi were the slight flow rate,the clear water and the shallow depth.The prelarva growed in still water or the slight flow rate surroundings.