A practical approach for assessing ecological risks associated with fish stocking programs

As wild fish populations continue to decline, fisheries managers are increa singly concerned about how hatchery operations might be contributing to dec lines of highly valued wild populations. Ecological risk assessments can pr ovide decision makers with critical information about potential effects of stocking. In this paper we describe a practical approach for assessing ecol ogical risks to select nontarget taxa (NTT) associated with fish stocking p rograms. This approach requires the completion of five tasks: (1) Determine acceptable impacts to NTT (e.g., impact of 10% to a species distribution, abundance, or size structure); (2) determine potential spatial-temporal ove rlap of NTT life stages with target taxon; (3) determine potential strong e cological interactions; (4) determine ecological risk; and (5) determine sc ientific uncertainty of ecological risk assessment. These tasks are accompl ished by analyzing information gathered from scientists, managers, and poli cy makers. The result of the assessment is a listing of the ecological risk s and associated uncertainties of failing to meet a stated objective for a variety of NTT. We also describe a decision matrix that prescribes various levels of uncertainty resolution, risk minimization strategies, risk contai nment monitoring, and stocking proposal implementation. Prescriptions refle ct the amount of ecological risk and scientific uncertainty. Application of ecological risk assessment concepts to hatchery stocking decisions allows for a balanced approach when evaluating the benefits of hatchery stocking r elative to ecological costs to nontarget populations and the economic costs of risk management.