Research Article

Differences in anti-predator behavior and survival rate between hatchery-reared and wild grass carp (Ctenopharyngodon idellus)

¹ State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China
² University of Chinese Academy of Sciences, Beijing 100049, PR China
³ College of Bio-Resources and Food Engineering, Qujing Normal University, Qujing 655000, PR China
⁴ Université de Toulouse, UPS, CNRS, ENFA, IRD, Laboratoire Évolution & Diversité Biologique UMR5174 EDB, 118 route de Narbonne, Toulouse, France
⁵ The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan 430072, PR China

^* Corresponding author: tlzhang@ihb.ac.cn

Received: 17 March 2017
Accepted: 4 September 2017

Abstract

Grass carp Ctenopharyngodon idellus, is the primary freshwater species produced in China. Because natural populations have shrunk in the wild, restocking programs using hatchery-reared fish have emerged. Artificial rearing could affect fish anti-predator behavior, thus decreasing their survival in the wild. The impact of artificial rearing on C. idellus's behavior remains unknown because empirical studies are scarce. In this study, we compared anti-predator behavior and survival rate between hatchery-reared and wild C. idellus. Both hatchery-reared and wild C. idellus displayed clear anti-predator behavior when exposed to visual and odor cues of a predator. However, hatchery-reared C. idellus showed significantly lower aggregation index (reflecting shoaling behavior), inspection rate and spent less time in risky area compared to their wild counterparts. When directly exposed to predators, more hatchery-reared C. idellus were predated. This raises concerns about the efficiency of restocking programs and highlights the need to adjust artificial rearing and stocking conditions of C. idellus to produce fish that are better adapted to natural conditions.