A sentinel monitoring framework for identifying fish population responses to industrial discharges

We previously proposed a classification scheme to describe the responses of fish populations to anthropogenic stress. The original framework separated impacted populations into five response patterns, but had several limitations and deficiencies, including the subsequent description of additional patterns and the absence a pattern reflecting no detectable response of the population. The response framework has been reorganized based on new information and response patterns described in published literature. The sentinel monitoring framework provides a tool for initial interpretation of adult fish surveys and description of priority areas for subsequent studies to allow identification of the mechanism of impact. Subsequent, focused, follow-up studies are required to identify the stressor(s) once the impact mechanism has been identified. Response pattern separation requires information from the sampled fish population including age structure, energy expenditure and energy storage. The patterns represent characteristic responses to changes in food availability, adult mortality, recruitment failure and metabolic disruption. The framework requires the identification and appropriate sampling of comparable reference sites, but the sentinel monitoring framework has proved to be a useful tool in preliminary trials, and should provide a focal point for cumulative effects studies using fish populations.