Sexual Dimorphism and Discrimination of Barbel Steed (Hemibarbus labeo) in the Jinhe River, China: An Indicator of Habitat Status

Abstract

Sex identification is linked to sexual dimorphism and is an important study issue in fish biology and aquaculture. However, owing to the unmarked sexual heteromorphism between adult Hemibarbus labeo, it is often difficult to distinguish their sex by visual observation. This study aimed to find a simple and reliable morphometric criterion for the sex identification of H. labeo using discriminant models. Forty-two morphometric traits of sixty-eight H. labeo individuals collected from the Jinhe River were measured, and 41 standardized features were calculated and analyzed. Eight trait variables from 41 standardized attributes were screened using stepwise discriminant analysis. The total classification accuracy of the model was 95.59%. Twelve standardized features significantly differed between male and female H. labeo individuals (p < 0.05). The condition factor, body height, dorsal fin coxal length, the distance between the pelvic and anal fins, and body length were significantly greater in females than in males (p < 0.05), suggesting that females of H. labeo in the Jinhe River were plumper than males, with a larger body size, but a smaller caudal peduncle. These results implied that the sex identification of H. labeo can be performed using the discriminant equation established in this study. This study provides a theoretical basis for endangered fish species protection and their artificial propagation.