Path analysis of effects of morphometric attributes on body weight of Exopalaemon carinicauda

In order to ascertain the optimal and measurable indices used in artificial breeding of Exopalaemon carinicauda,the effects of morphometric attributes on body weight of E.carinicauda were analyzed by path analysis.Besides body weight,ten morphometric attributes,including the body length,total length,carapace length,carapace width,carapace height,first abdominal segment height,first abdominal segment width,abdomen length,number of upper frontal eminence spin and number of lower frontal eminence spin were recorded for 177 four-month-old E.carinicauda.The correlation coefficients among all attributes were calculated,and the path coefficients and determination coefficients were calculated by taking the body weight as a dependent variable,and the other ten morphometric attributes as independent variables in path analysis.The data indicated that the path coefficients of four morphometric attributes(body length,carapace width,carapace height,first abdominal segment width)to body weight reached significant difference(P0.01)level.Among above four significant factors for body weight,body length showed the greatest effect on body weight with the direct effect efficiency of 0.468* *.The direct effects of total length,carapace length,first abdominal segment height,abdomen length,number of upper frontal eminence spin and number of lower frontal eminence spin on body weight were quite low,therefore,they were regarded as insignificant factors influencing the body weight.The stepwise regression analysis established a multiple regression equation on the effects of body length,carapace width,carapace height,first abdominal segment width on body weight with partial regression coefficients of-3.277,0.470,0.980,0.528 and 1.942 separately.Judging from the high multiple-correlation coefficient(R2=0.976),the main attributes(body length,carapace width,carapace height,first abdominal segment width)determining the body weight have been selected.