A review and evaluation of study design considerations for site-specifically assessing the health of fish populations

Since there are not any well developed procedures for site-specifically evaluating the health of fish populations, most field surveillance programs have been restricted to collecting information on chemistry, toxicity, bioaccumulation, biochemical alterations orin situ benthic community structure. Identification of the mechanism and significance of contaminant effects on fish populations depends on the ability to identify changes and to distinguish changes in survival, food availability or food conversion efficiency, from coincidental changes associated with alterations in habitat or natural variability. Preliminary identification of the characteristics of adult fish can be used to cost-effectively focus financial resources on the alterations which are of relevance to interpretation of impacts and identification of causal factors. Proper interpretation requires that appropriate attention be given to monitoring level and strategy, selection of species and timing of sampling, sample size requirements and choice of reference site.