This is the Mid-Atlantic regional component of NOAA?s Estuarine Living Marine Resources (ELMR) Project, a national database of ecologically and economically important fishes and invertebrates in the Nation’s estuaries. The distribution and relative abundance are depicted in a consistent format for 61 species of fishes and invertebrates, in 22 estuaries in coastal Massachusetts (south of Cape Cod), Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, and Virginia. Species were selected according to a set of criteria, which consider their commercial, recreational, and ecological value, as well as their utility as an indicator of environmental stress. For each species, five life stages are considered – adults, juveniles, larvae, spawning, and eggs – with some exceptions based on individual species life history. Each estuary is subdivided into one to three salinity zones (Tidal Fresh, Mixing, and Seawater). Relative abundance was ranked on a five-tier scale by month for each life stage of each species, in each salinity zone of each estuary. Details of the methods for the Mid-Atlantic ELMR component can be found in Stone et al. (1994) and Nelson and Monaco (2000).