INTERSPECIFIC COMPARISON OF THE BEHAVIORAL RESPONSES TO PREDATION STRESS IN FOUR CYPRINIDS

In nature, fish often suffer from various of predation stress. Thus, prey fish often respond to their predators by adjusting their behavior, which is called anti-predator behavior. Investigating the correlations between behavioral characteristics of fishes and their physiological functions and habitat environment at the interspecific level is helpful to understand the internal mechanism of interspecific differentiation of behavioral strategies of fishes, therefore ecologically important. The previous predation stress experience and the presence of predators in the current environment may act different effects on the behavior of prey fish, because the prey fish need to maximize survival and minimize the cost of anti-predator behavior. The aims of this study were to compare the effects of previous predation stress experience and the presence of predators in the current environment on the behavior of prey fish, and to examine whether there are interspecific differences for these effects. In this study, the effects of both previous predation stress experience and present predation stress on exploration, activity and boldness in juvenile bream (Parabramis pekinensis), grass carp (Ctenopharyngodon idellus), crucian carp (Carassius auratus) and qingbo (Spinibarbus sinensis) were investigated. The results showed that, the effects of predation stress experienced early on the behavior of fish are quite different from those of predators in the current environment, and these effects are also quite different among the four species. The naïve bream, grass carp and qingbo performed anti-predator behavior to the strange predator snakehead fish (Channa argus), which suggested that these three fish could recognize the strange predator snakehead fish, but such a recognition is still different from the recognition obtained from real predation experience. The bream and qingbo with predation stress experience did not exhibited anti-predator behavior in blank environment, which may be a strategy for conserving energy. In general, grass carps were more sensitive to predation stress and environmental treatment, while the response of qingbo was more conservative. The differences in anti-predator responses among the four cyprinids may be closely related to the physiological phenotypes of the four cyprinids, such as morphology and swimming performance, and the predation pressure in the habitat environment. In terms of similarities, all the four species respond to predators by maintaining high levels of swimming in the presence of predators. Maintaining this stress state may be critical to keeping the prey fish stay away from the predator and staying alert at all times.