Endocrine-disrupting chemicals (EDCs) in the environment may alter the population dynamics of wildlife by affecting reproductive output. This study describes a matrix modeling approach to link laboratory studies on endocrine disruption with potential ecological effects. The experimental model used is cunner (Tautogolabrus adspersus), which inhabit estuarine and marine areas where sewage treatment and other discharges containing estrogenic EDCs are likely. To test the effects of estrogenic exposures on fecundity, reproductively active cunner were exposed in three separate experiments by implanting 17beta-estradiol, estrone, or 17alpha-ethynylestradiol subcutaneously in a slow-release matrix at 0.05, 0.5, and 2.5 mg/kg. Egg production per gram female and egg viability were determined daily for a 1-week preexposure period and then for a 2-week exposure period. The mean number of eggs produced per gram female and egg viability (%) were calculated for the initial preexposure period and the 2-week exposure period for each experiment. Significant changes were observed in egg production per gram female in the high-17beta-estradiol treatment (P = 0.07) and high-17alpha-ethynylestradiol treatment (P = 0.04). A significant increase was observed in egg viability (%) in the low-17alpha-ethynylestradiol treatment (39.0%; P < or = 0.05). Cunner population response was projected using an age-structured matrix population model parameterized with published survival and fecundity estimates. By incorporating reproductive response data from laboratory exposures, model projections were used to describe how reproductive changes by estrogen treatment could alter cunner population growth rate (lambda). Published by Elsevier Inc.