Mark Teply, Cramer Fish Sciences, markt@fishsciences.net (Presenter)
Steve Cramer, Cramer Fish Sciences, steve@fishsciences.net


Migratory organisms present a challenge when predicting exposure to pesticides given their uneven distribution in time and space. We will present a spatially and temporally explicit framework for estimating the co-occurrence of juvenile salmon and pesticides in the Willamette Basin, Oregon. This framework was developed as an alternative to ecological risk assessments conducted in recent Biological Opinions related to agricultural pesticides. We extend it here to address forest pesticide use. The framework incorporates information about patterns of juvenile salmon distribution along with information about patterns of pesticide use for estimating potential exposure through direct contact. This framework also incorporates information about the spatial and temporal distribution of the salmon prey base which for estimating indirect effects. In both instances, we demonstrate that by using information about the distribution of juvenile salmon and their prey, the framework yields a better understanding of the proportion of organisms potentially impacted by pesticides. We show how such information can improve risk management and how it can influence regulatory decisionmaking.