Habitat-specific anti-predator behavior variation among pale chub (Zacco platypus) along a river

Abstract

Theory indicates that the anti-predation behavior of a fish species will depend on predation threats in a way that tends to improve the probability of surviving predation. Pale chub (Zacco platypus), a small Asiatic cyprinid, is widely distributed in both high- and low-predation reaches of the Wujiang River. To test whether the anti-predator behavior of pale chub along the Wujiang River varied in fish living in habitats under different levels of predation pressure, we measured spontaneous swimming activity, risk-taking behavior, utilization of shelter and boldness in pale chub collected from both high- and low-predation habitats in the Wujiang River. The fish from high-predation populations showed less spontaneous swimming activity and risk-taking behavior compared with those of the fish from low-predation populations. However, neither utilization of shelter nor boldness exhibited any significant differences between high- and low-predation populations. One reason for this result may be that in their daily lives, the pale chub in the high-predation population primarily respond to the presence of predators by decreasing spontaneous swimming activity and risk-taking behaviors when threatened rather than increasing utilization of shelters and showing less bold behavior. The lack of an increase in shelter utilization and the lack of a decrease in boldness in response to predation pressure may be a compromise to allow foraging and growth.