The Study Of The Growth Of Juvenile Chinese Mitten Crab And The Identification Of Different Families

The juvenile Chinese mittencrab(Eriocheir sinensis)of Guanghe No.1 were selected as the research materials,which was the first new strain of Chinese mitten crab in China.Using statistical methods to compare the growth traits in different families of juvenile Chinese mitten crab cultured in outdoor and indoor,respectively.Pedigree determination based on morphological characters and microsatellite DNA markers.The appropriate method of pedigree determination were put forward.1.Megalopa larvae of A,B and C families of Chinese mitten handed crab(Eriochier sinensis)were reared in a 40 m2 net cage(6.50 m×6.15 m)at a stocking density of 2500 individuals per cage in early June of 2015.Some of the juveniles were randomly sampled from the net cages and comparatively reared in an indoor 300 L tanks at a stocking density of 30 individuals per tank later July of 2015.Carapace width,carapace length and carapace weight reared in the juveniles in the ricefields and in an indoor tank were measured in a some 15 day interval from August to October in 2015,and the data above were analyzed by multiple analysis of variance and repeated measures analysis of variances from environmental factor,family factor and the growth traits.The results showed that there was no significant influence of rearing environmental factor on the growth traits in the crab juveniles in family A(P>0.05),with very significant influence on those in family B(P<0.01),and significant influence on those in family C(P<0.05)except for at the beginning period of growth(P>0.05),indicating that the juveniles in family A had a certain environmental adaptability.Meanwhlie,family factor was found to have significant effects on growth traits of the crab juveniles in different periods(P<0.05),which shows that genetics plays an important role in the growth of crab juveniles.The correlation analysis of rearing environments revealed that there was very significant positive correlation between growth traits(carapace width and carapace length)and rearing environment,with correlation coefficients of 0.314 and 0.305(P<0.01),and no significant correlation with the carapace weight(r=0.146,P>0.05).The findings indicate that the offspring will have a certain adaptation when carapace width and carapace length are chosen as selection indices in two different rearing environments.2.18 metric parameters representing morphological characters of juvenile crab from six families were measured and then analyzed by the cluster analysis and the stepwise discrimination.The results of cluster analysis shows: The morphology of juvenile Chinese mitten crab from family a,family b,family d and family e were similar,but quite different from family c and family f.The result of stepwise discrimination based on the 10 morphological parameters with high contribution to the discrimination shows that the accuracy of discrimination of family a,family b,family c,family d,family e and family f were 83.3%?93.3%?96.7%?93.3%?0% and 100%,respectively.The average of fitting accuracy of discrimination was 77.8%,and the average of fitting accuracy of discrimination of cross-validation was 61.1%.However,the actual effect is not ideal.The member of family a(e)was tend to clustered to family e(a),the accuracy of discrimination of family b,family c and family f were 53.3%,80% and 60%,respectively,while family d was 0%.Therefore,the discrimination analysis based on morphological parameters from different families was not suitable for our breeding families,and it is hardly to discrimination of different families according to the morphological parameters.3.The Guanghe No.1 strain of Chinese mitten crab Eriocheir sinensis has been subjected to multiple selective events for several years.Conventional methods were insufficient to reveal the genetic diversity and pedigree information of Guanghe No.1.In this study,we used twelve microsatellite DNA markers to assess the genetic diversity and parentage determination of five families of Guanghe No.1 by using simulation and real data analysis.The analysis of genetic diversity parameters of twelve microsatellite markers suggested high level of diversity within the total sample.The polymorphic information content of twelve microsatellite markers indicated that they all exhibited high information.The alleles frequency date-based simulation indicated that the combined exclusion probability values would be over 95 and 97%,respectively,when four and five microsatellite markers were used.Based on the simulation,99% of progenies were assigned to their putative parent pair when four microsatellite were used,while the rate of assignment success for the real data set was 97%.Moreover,when the number of microsatellite was up to seven,all offspring from five full-sib families were 100% allocated to their parents.The unweighted pair-group method with arithmetic average dendrogram demonstrated that 94% of the progeny can be clustered into their own families.This study indicated that the previous artificial breeding program maintained a good genetic diversity of Guanghe No.1,and these microsatellite markers would have a great application in parentage determination in this strain.All of these basic research work we have done will be useful in breeding and provide theoretical reference for production of Chinese mitten crab.