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.
