The West River in New Haven, CT was sampled for anadromous fish from March through November of 2000. Samples were collected to determine population densities, species diversity, spawning locations, spawning success, young of the year (YOY) nursery locations, and recruitment. Approximately 3500 Alosa pseudoharengus and Alosa aestivalis (herring) entered the river. These fish were concentrated in the mainstem, and successfully spawned in at least two locations. Discharge, temperature, and precipitation measurements were taken at the sampling sites. Herring YOY were found in nursery areas and passed the tide gates on their way to Long Island Sound. YOY that lived below the tide gates, prior to complete emigration, experienced constantly higher salinity levels. Approximately fifty-three adult Dorosoma cepedianum (gizzard shad) were found in the river. Virtually all of these fish were found in one location. A dam, located approximately 3 miles from the mouth of the river, blocks fish passage to two ponds. The spawning habitat suitability of the largest pond was tested by adding 400 adult herring to it, and monitoring for the presence or absence of young of the year. This study has been conducted to develop baseline information prior to the construction of a fish ladder over the dam.