Risks of toxic contaminants to exploited fish populations: Influence of life history, data uncertainty and exploitation intensity

We investigated three aspects of the use of toxicity test data for population-level risk assessment: (a) the influence of life history characteristics on vulnerability to contaminant-induced stress, (b) the importance of test data availability and (c) the influence of exploitation intensity. We quantified population-level effects of chronic contaminant exposure by coupling standard toxicity test data to matrix-type population models derived from long-term field studies of the Gulf of Mexico menhaden (Brevoortia patronus) and Chesapeake Bay striped bass (Morone saxatilis) populations. We used statistical regressions to quantify the uncertainty inherent in using test data ranging from life cycle tests to quantitative structure-activity relationships (QSARs) to estimate effects of contaminants on the survival and reproduction parameters of the population models. We found that because of differences in life history, menhaden and striped bass differ in terms of their capacity to sustain the same level of contaminant-induced mortality. Changes in exploitation intensity affect the responses of both populations to the same level of additional contaminant-induced mortality. However, the quantitative effects of both factors are negligible compared to the uncertainty introduced by estimating long-term effects from short-term tests or QSARs. Our results suggest that consideration of life history may be important primarily for site-specific assessments. For screening-level assessments, the substantial differences in uncertainty associated with different types of test data are of much greater concern.