Effects of Different Cultivation Modes on Morphological Traits and Correlations between Traits and Body Mass of Crayfish (Procambarus clarkii).

Simple Summary: It is well known that animal morphological traits are influenced by both genetic and environmental factors, but further research is needed to investigate the extent to which the environment influences morphological traits under the same genetic background. As one of the most widely distributed freshwater shrimp species in the world, the crayfish has a strong territorial and combative habit, so the influence of the aquaculture environment on its morphological development is more obvious. Meanwhile, under the same environment, different sexes of crayfish also showed corresponding morphological differences due to their reproductive functions. In this study, juvenile crayfish hatched from the same population were cultured in different growing environments, and the effects of environment and sex on their morphological characteristics were evaluated by mathematical models such as correlation analysis, pathway analysis, and gray correlation, so as to provide a basis for the artificial selection of crayfish in the later stage of development. In this study, juvenile crayfish hatched from the same population were cultured in different growing environments: pond (D1), paddy field (D2), and aquaculture barrel (D3), and fed for 60 days. Crayfishes were selected randomly, females and males, 50 tails each from six groups (D1-♀, D1-♂, D2-♀, D2-♂, D3-♀, D3-♂) to measure the following morphological traits: full length (X1), body length (X2), chelicerae length (X3), chelicerae weight (X4), cephalothorax length (X5), cephalothorax width (X6), cephalothorax height (X7), eye spacing (X8), caudal peduncle length (X9), and caudal peduncle weight (X10). We found that the coefficient of variation (CV) of X4 was the largest in each culture mode, and males (28.58%~38.67%) were larger than females (37.76%~66.74%). The CV of X4 of crayfish cultured in D1 and D2 was larger than that of D3. All traits except X8 were positively correlated with body weight (p < 0.05). After pathway analysis, we found that X4, X5, X7, and X10 were significantly correlated with the body weight of D1-♀; the equation was YD1-♀ = −29.803 + 1.249X4 + 0.505X5 + 0.701X7 + 1.483X10 (R2 = 0.947). However, X2, X4, and X6 were significantly correlated with the body weight of D1-♂; the equation was YD1-♂ = −40.881 + 0.39X2 + 0.845X4 + 1.142X6 (R2 = 0.927). In D2-♀, X1, X4, X5, and X10 were significantly correlated with body weight; the equation was YD2-♀ = −12.248 + 0.088X1 + 1.098X4 + 0.275X5 + 0.904X10 (R2 = 0.977). X4 and X5 played a major role in the body weight of D2-♂ with the equation: YD2-♂ = −24.871 + 1.177X4 + 0.902X5 (R2 = 0.973). X3 and X10 mainly contributed to the body weight of D3-♀ with the equation: YD3-♀ = −22.476 + 0.432X3 + 3.153X10 (R2 = 0.976). X1 and X4 mainly contributed to the body weight of D3-♂ with the equation: YD3-♂ = −34.434 + 0.363X1 + 0.669X4 (R2 = 0.918). Comparing the pathway analysis with the gray relation analysis, we could conclude that the traits most correlated with body weight in D1-♀ were X10 and X7; in D1-♂, X6; in D2-♀, X10, X1, and X5; in D2-♂, X5; in D3-♀, X10; and in D3-♂, X4 and X1. [ABSTRACT FROM AUTHOR]