Variation Of Growth Characteristics And Otolith Morphological Characteristics Of Anadromous Spawning Stock For Coilia Nasus In The Yangtze River

Coilia nasus, herring-shaped head （clupeiformes）, Anchovies（engraulidae）, coilia. It usually lives in the China, Japan and Koreanalong the coast. After spring sexual maturity, brood stocks breeding eggs,hatching from the estuary into the river, lake. At last Larvae back to thesea to live. However, in the Lower Reaches of the Yangtse River, TaihuLake, Chaohu Lake and other lakes, living a type of settlement C. nasusstock, called the lake anchovy（C. nasus taihuensis） as a subspecies of C.nasus, which is different from the anadromous C. nasus in shape and lifehabits.Since1970s, coilia has been clarified into two ecological types, oneis miratory ecotype also called C. coilia; the other is the freshwaterecological settlement, including the lake anchovy and short-jaw anchovy.There are two kinds of methods for studying otolith shape: one isTraditional Otolith Morphometrics （TOM） also called Simple OtolithMorphometrics （SOM）; the other is Fourier Shape Analysis （EFA）. Thelargest difference between them is emphasis point. TOM studies axes ofthe otolith, however, EFA studies outline of the otolith.Since1970s, the resource and analysis the variation of biologycharacteristics about C. nasus in Yangtze River had been surveyedmassively in China. Some scholars also begin to survey the resource andanalysis the variation of biology characteristics about C. nasus in YangtzeRiver recently. There is no dynamic analysis of biology characteristics inanadromous C. nasus. In order to providing foundation for the protection and rational utilization of resources in C. nasus, this paper analyzes thevariation of biology characteristics for anadromous spawning stock,which from Yangtze estuary to the Section of wuhu in anhui. And alsostudy the variation of otolith morphological characters in2age-groups.The main Results are as follows:1、In this study，we analyzed the299specimens collected at threelocalities，which included Jiuduansha （JDS） in Shanghai city，jingjiang（JJ） in Jiangsu province，Wuhu （WH） in Anhui province，from April toMay2009．The results show that the body length（BL） of C. nasus rangefrom15.8to32.8cm （average23.3±3.5cm），most of which rangebetween18and24cm（52.51%）．The body weight（BW） change from11.83to143.80g （average48.19±24.89g） of which mainly from10.00to50.00g（59.53%）．The BL and BW of WH stock is smaller than that ofJDS and JJ stock significantly（ANOVA, p=0.000<0.01）．The299specimens contain4age-group of which ranging from1to4．51.28%and53.97%of specimen are three years old in JDS and JJ stockrespectively．In contract，85.26%of specimen are two years old in WHstock．Our result also shows that the sex ratio（∶）of299specimensis1:1.57for all the samples，including1:1.28for JDS stock,1:1.46for JJstock and1:1.97for WH stock, gradually increase along with YangtzeRiver upwards．The average fatness of299specimens is0.350±0.049，but JJ stock larger than WH and JDS stocks significantly when they are inthe same age-group. This result may help us to explain why big individualC. nasus is so commercially valuable in this Section of Yangtze River．2、In this study，we analyzed the171anadromous specimenscollected at Jiuduansha （JDS）、jingjiang （JJ）、Wuhu （WH），from Aprilto May2009and54settlement specimens collected at Taihu （TH）．Theage is reading from the grinding picture of otoliths. All of225specimensare2years old. The results of left sagittal otolith shape index analysis of171Specimens in2years old of anadromous Coilia indicated that theparameters mean of the otolith measurement gradually increased in theprocess of anadromous spawning migration from Yangtze River to the Wuhu section. There is no significant difference （P>0.05） in the otolithmeasurement parameters between in JDS and JJ stocks. From JJ to WHsearch, the value of measurement parameters （otolith Area, Perimeter,Weight, Width, Length, Maximum Ferect Diameter, Minimum FerectDiameter, Maximum Radius, Minimum Radius） increase significantly.There are difference in otolith Area, Perimeter, Weight, Width, MinimumFerect Diameter and Minimum Radius between in anadromous stock andTH stock in the same age-group, significantly（P<0.05）. However, Thereis no difference in Length, Maximum Ferect Diameter, Maximum Radiusboth of them （P>0.05）.77.8%of shape indices has no difference among JDS stock、JJstock、WH stock（P>0.05）. The Format-factor, Circularity, Rectangularityare increased both in JDS stock and JJ stock, significantly. There issignificant difference in Circularity between in JJ stock and WH stock（P<0.05）. This result indicates that in the process of anadromousspawning, otolith outline became more and more regulation, close to therectangular, rather than roundness. Compared with WH stock, therectangularity is increased in JJ and JDS stock, significantly（P=0.022<0.05）. This indicates that Otolith outline became close toroundness, and they are not persistent. There is difference in X1^X₃、X5^X9in JJ stock and TH stock, significantly. There is difference in X1、X₄^X9between in JJ stock and TH stock, significantly. There isdifference in X1、X5^X9between in WH stock and TH stock significantly.The discriminate analysis of traditional otolith morphometricsindicated that the accuracy of discrimination was51.1%, and the overlaprate of discrimination among JDS stock、JJ stock and WH stock is veryhigh; However, if the three Yangtze River stocks were normalized as aclass, synthetic discriminate rate can up to82.2%. The principalcomponent analysis showed the same results.3、The results of left sagitta otolith Fourier morphometrics analysisof171Specimens in2years old of anadromous Coilia indicate that if thethree Yangtze River stocks were normalized as a class, and than compare to TH stock, showed that only17of the225individuals was wronglyaccused, that the rate of discrimination up to92.4%.Using Fourier analysis on JDS, JJ and WH and TH stock, thediscriminate success rate is just from35.2%to51.9%, and the overlap isvery high. This indicates that which in the process of anadromousspawning, there is no differences of otolith outline.