Production forgone: An alternative method for assessing the consequences of fish entrainment and impingement losses at power plants and other water intakes

• Published in: Ecological modelling 1984-01, Vol.24 (1), p.79-111
• Main Author: Rago, Paul J.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Demecology; Fundamental and applied biological sciences. Psychology
• ISSN: 0304-3800; 1872-7026
• DOI: 10.1016/0304-3800(84)90056-5

Losses of fish at power plant and other water intakes have immediate as well as future impacts. Not only is fish biomass removed from the aquatic system, but also the biomass that would have been elaborated by the cohort is not available to other predators. A simple biological production model was modified to allow projections of future impacts associated with current losses of fish and fish larvae. To compute these projections, it is assumed that short-term future responses with be similar to recent survival and growth rates, deducible from analysis of current population structure. The model has several advantages over the approaches. First, a dynamic population model need not be specified. Second, the relative importance of ichthyoplankton versus juvenile and adult fish losses can be compared directly. Third, the ecological effects of future losses can be addressed by cosidering the predicted size-frequency distributions. Finally, the relative uncertainty of the forecast can be assessed. The effectiveness of two commonly used mitigation techniques was explored. Reductions in entrainment-induced mortality were assessed along with exclusion of adult fish using a size selective screening device. If entrained organisms contribute most to the production forgone, then reductions in entrainment mortality will be more effective than screening of adult fish. Extensive sensitivity analysis of the model indicated the relative importance of various growth and survival parameters. Survival rates in the first year of life were critical parameters. A computer program (in FORTRAN) generates production forgone estimates by age group, evaluates the efficiency of various mitigation measures and computes the sensitivity of production forgone with respect to each parameter in the model.