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.
"It takes much longer to rebuild a stock when numbers are that low," says Dale Weinrich, a DNR biologist. Shad also are less prolific and more sensitive to pollution than rockfish, he notes.
Now, after nearly a decade of stocking the Susquehanna with millions of newly hatched shad larvae, fisheries officials say they are starting to see early signs of a rebound.
But much more needs to be done, they caution, to meet their long-term goal of having a self-sustaining population of 3 million spawning shad in the Susquehanna.
A major hurdle was cleared this spring when Philadelphia Electric Co., which operates Conowingo Dam, finished a new $12.5 million fish lift there, ending a 30-year-old feud between the utility and Maryland and Pennsylvania.
The lift, which replaces a smaller one used since the 1970s, can hoist 750,000 shad and 5 million river herring per year over the 110-foot high dam. This past spring, more than 27,000 spawning shad made it over Conowingo, nearly double the previous year's total.
But three more dams still block the Susquehanna upriver, so those fish had to be trucked 30 miles upriver in water-filled tanks to continue their spawning runs above York Haven, the northernmost dam.
Federal and state officials from Maryland and Pennsylvania now are pressing the utilities that own the three dams above Conowingo to build fish lifts or ladders as well. They want the entire river reopened to spawning shad, herring and rockfish by spring 1995.
Peter Dunbar, chief of power plant review for the Maryland Department of the Environment, estimates that installing fish passageways at Holtwood, Safe Harbor and York Haven dams will cost $13.3 million initially.
But the three utilities that own the dams, including Baltimore Gas & Electric Co., are reluctant to commit themselves.
BG&E officials, who own Safe Harbor dam with Pennsylvania Power & Light, say the utilities are willing to pay for fish passageways, but want more studies first of the shad population and of the proper location and design of lifts or ladders.
"We really are concerned about building something that doesn't work," says Elizabeth Bauereis, BG&E's director of environmental programs.
Until shad populations get much larger, the utilities want to keep trucking spawning shad upriver from Conowingo, an operation they are paying for. As many as 350,000 fish can be handled that way, more than 10 times the number now being transported, according to a utility consultant's report.