In the Susquehanna River above the Three Mile Island nuclear power plant, thousands of little American shad fingerlings are spilling through a sluiceway over York Haven Dam. They are clearing their first hurdle in a 300-mile odyssey that will take them down the Chesapeake Bay to the Atlantic Ocean.
After roaming the coast from Newfoundland to North Carolina for three or four years, these young shad will swim back toward the bay one February, seeking to spawn in the river where they spent the first few months of life.
But many may not make it. For, in spite of a multimillion-dollar effort to restore the bay's decimated shad stocks, their long-term recovery remains a long way off.
Three hydroelectric dams in Pennsylvania still bar the migratory fish from their traditional spawning grounds on the Susquehanna, which stretch 350 miles upriver to Binghamton, N.Y. And new research suggests that before they can even reach the mouth of the bay, thousands of shad, including many reared in hatcheries to stock the river, are being caught in fishermen's nets off Virginia's coast and possibly Maryland's.
Bony but tasty fish prized by some for the roe, or eggs, of spawning females, shad remain scarce in the bay, despite an 11-year Maryland fishing moratorium and a restocking effort that has put well over 100 million hatchery-spawned shad larvae in the Susquehanna.
Their depleted state results from decades of intense fishing, pollution and the construction of four dams on the Susquehanna, the bay's largest tributary and most important shad-spawning river.
At the turn of the century, commercial fishermen hauled in 17.5 million pounds of shad baywide. But the catch plummeted after Conowingo Dam was finished on the lower Susquehanna at the Harford-Cecil county line in 1928. Fish populations elsewhere in the bay also fell until Maryland imposed a moratorium in 1980.
They have rebounded some since then. The Department of Natural Resources figures there were about 140,000 shad in the lower Susquehanna and upper bay last spring, up from 126,000 the year before.
But shad's recovery has been nothing like the dramatic rebound of striped bass, or rockfish, which regained abundance after just five years of fishing curbs.
That may be because shad had dwindled almost to oblivion by the time Maryland moved to protect them. State biologists estimate there were only about 3,000 left in the lower Susquehanna and upper bay when fishing for them was banned.
