The Parker River Blueback Herring Run
A close relative to the alewife, blueback herring (Alosa aestivalis) also utilize the Parker River system for spawning and nursery habitat. Returning from the ocean each spring to spawn in freshwater, bluebacks run upsteam to the first barrier and commence spawning when water temperatures warm to between 51 and 57 degrees Fahrenheit. Spawning in the Parker River system takes place in the reach of river immediately downstream from the Central St. dam and in a short section of the Mill river below the Glen Mills dam. Although known to proceed further upstream through fishways in some river systems, Parker River bluebacks have not been observed passing above the first dam. Blueback herring numbers have not been impacted by the poor condition of the fishways.