The number counted at the Conowingo Dam has fallen more than 90 percent in seven years.
The Atlantic States Marine Fisheries Commission says the numbers are down all along the East Coast. The numbers have fallen since authorities stepped in to protect a leading predator, the striped bass. But pollution and excessive fishing also considered factors in the shad's decline.
The commission is planning public hearings on whether more restrictions should be imposed on catching American shad. Fishing for shad is banned in Maryland and in some Pennsylvania waters, but not in several nearby states.
