Neophobia and the assessment of predation risk in aquatic systems.

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As a result of the nonconsumptive effects of predation, prey are often forced to trade-off critical activities such as foraging, courtship, territorial defence, in favour of increased risk assessment and predator avoidance. Key to the ability to balance these trade-offs is the reliable assessment of local predation threats. However, the ability to make such risk assessments is difficult under conditions of ecological uncertainty (defined as ambiguity resulting from imperfect information regarding local predation threats). Uncertainty may arise as a result of spatial and temporal variability in predation risk or with local variability in density and/or diversity of the predator guild. As uncertainty increases, the chance of inappropriate responses to local threats likely increases; magnifying the costs of nonconsumptive effects of predation. In response to uncertainty in risk, prey may rely on acquired information (learning) in order to achieve sufficient behavioural plasticity to respond to variable threats. However, learning comes at a cost as prey must survive the initial encounter with a predator in order to acquire ecologically relevant information. Our model of neophobic predator recognition, argues that the response to novel cues is a phenotypically plastic response to uncertain predation risk. The response to unknown predator cues may provide naïve prey with an adaptive mechanism to avoid the ‘first encounter’ cost associated with the well-documented learned predator recognition while still ensuring sufficient behavioural flexibility to respond to uncertain threats. The first objective of our proposal is to test the ecological constraints and survival value shaping neophobic predator recognition. These data will allow us to develop a generalized model of neophobia based on the combined adaptations to chronic threats and short-term behavioural decisions. The proposed experiments (and others that may arise from the data collected) are aimed at exploring the role of individual perception of risk, predation risk and predator diversity play in the acquisition and retention of neophobic responses to novel predator cues. Our second goal is to apply our models of neophobia and ecologically-relevant learning to enhance post-stocking survial of hatchery-reared fishes. Each year, millions of hatchery-reared juvenile salmonids are stocked into natural waterways as part of ongoing efforts to re-establish or maintain natural populations. However, the combined effects of lack of experience and hatchery selection leads to poor post-stocking survival. One commonly advocated method to enhance post-stocking survival is life-skills training, including conditioning hatchery-reared prey to recognize common predators prior to stocking. Only a handful of studies have directly tested the ‘real-world’ benefits of life-skills training, with mixed to negative results. Using primarily field-based protocols, we will assess the feasibility of life-skills training to improve the success of pre-stocking conditioning programs. The impact lay in the application of behavioural ecology to the enhancement of post-stocking survival of hatchery-reared fishes. Increased post-stocking survival of hatchery-reared fishes (especially salmonids) will have direct benefits for ongoing and future conservation and recovery programs. In addition to the efforts to enhance commercial and recreational fisheries, our results will also benefit conservation efforts for locally endangered fish populations.