Animals balance feeding and anti-predator behaviors at various temporal scales. The Risk Allocation Hypothesis suggests that frequent or lengthy predation risk can cause one of two modifications of prey feeding behavior: 1) postponement of feeding to less risky periods, or 2) resumption of feeding behavior despite persistent risk. North Pacific flatfishes exhibit a wide range of responses when confronted with predation risk, but their response to risk frequency has not been examined. Laboratory experiments were conducted with juvenile English sole (Parophrys vetulus), northern rock sole (Lepidopsetta polyxystra), and Pacific halibut (Hippoglossus stenolepis), which inhabit nearshore nurseries as juveniles and have been shown to exhibit different levels of risk aversion: English sole are risk prone, rock sole are risk averse, and Pacific halibut are risk sensitive. We observed the feeding and anti-predator behaviors of young-of-the-year of each species following exposure to three levels of predation risk: no risk, infrequent risk (two times per day) and frequent risk (five times per day).
Results/Conclusions
English sole responded to the frequent risk treatment with higher feeding rates than during the infrequent risk treatment, following a pattern of behavioral response that is predicted by the Risk Allocation Hypothesis; rock sole and halibut did not follow the predicted pattern, but this may be due to the limited range of treatments tested. Our observations of unique anti-predator strategies and species-specific ecologies suggest divergent trajectories of risk allocation for the three species.
