This project investigates the effects of the pyrethroid insecticide bifenthrin on salmon reproduction in the San Francisco Bay-Delta. The insecticide is frequently detected in runoff in Northern California and, like most pyrethroids, is highly toxic to fish. (Its use is banned in the European Union). Motivating this project is the concern that migrating salmon might be exposed to the pesticide in areas of the Bay-Delta where the fish are already subjected to highsaline conditions. The goal of this project is to examine whether high salinities exacerbate the insecticide’s toxicity. In project’s first year, the fellow conducted laboratory experiments with rainbow trout (a type of salmonid) to show that acute toxicity was indeed enhanced by exposure to high-salinity conditions. Continuing work will focus on documenting the combined effects of the toxin and salinity on a fish’s reproductive physiology. In the process of exploring this idea, the fellow hopes to identify biomarkers of reproductive dysfunction that might be able to detect whether a spawning adult was exposed to unhealthy levels of pesticide as a juvenile.