In ecotoxicological testing, there are few studies that report on reproductive output (egg production) of marine or estuarine fish. Cunner (Tautogolabrus adspersus) were studied as a potential model species to evaluate the impact of pollutants with estrogenic activity on reproduction in estuarine fish populations. Cunner inhabit marine and estuarine areas where contaminant discharges are likely. Baseline values for cunner gonadosomatic index (GSI), hepatosomatic index (HSI), and plasma vitellogenin (VTG) were determined in a field reference site (April 1999-December 1999). Male and female GSI indicated that cunner spawning is synchronized. Female HSI and VTG increased prior to GSI. From our laboratory observations, cunner are suitable for conducting experiments with reproductive endpoints indicative of both exposure (vitellogenin levels) and effects (egg production). However, cunner are not sexually dimorphic and stripping ripe fish is the only method to distinguish sex. In preparation for laboratory exposure studies with cunner, we designed a laboratory experimental holding system to accommodate cunner's reproductive behavior, a vertical spawning run to the water surface. Cunner were successfully acclimated from overwintering torpor to spawning condition in the laboratory by gradually changing the environmental conditions of fish held at winter conditions (4°C and 9:15-h light:dark photoperiod) to spawning condition (18°C and 15:9-h light:dark photoperiod). Our results show that cunner successfully spawned daily in the laboratory. They produced fertile eggs in our experimental system designed to accommodate cunner's vertical spawning runs, demonstrating that male and female reproductive behavior was synchronized in the laboratory. Our observations indicate that cunner would be a useful model species for evaluating reproductive effects of environmental contaminants in laboratory studies.