Researchers are reporting a significant drop in the number of shad migrating up the Susquehanna River. 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 began falling when authorities stepped in to protect a leading predator, the striped bass. Pollution and excessive fishing also have contributed to 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 Pennsylvania, but not in several nearby states.