 Today, 1/2 million river herring and Rainbow smelt ("Osmerus mordax") run up the river each year to spawn (although they are not able to ascend the fish ladders and only utilize the tidal portions of the river).Several nesting platforms were constructed and are in use by the Osprey, or fish hawk, ("Pandion haliaetus"), which has white under parts and a wingspread of 5 to 6 ft (152 to 183 cm).It feeds almost exclusively on live fish including flounder, herring and perch, and is usually seen hovering over the water, into which it plunges feet first to grasp its prey.