Once nearly wiped out, shad stage an uneven comeback in the Chesapeake Bay

Once severely depleted, American shad - the fish that fed the nation's founders - are finally making a comeback in the Chesapeake Bay. Their return so far has been uneven, though.

Spawning runs of the migratory fish have surpassed restoration goals in two of the bay's major tributaries, the Potomac and Rappahannock rivers, the Chesapeake Bay Program announced Friday. Shad numbers have shown varying gains in a couple other Virginia rivers, but they remain scarce in the bay's largest tributary, the Susquehanna, as well as in the upper James River.

"A rise in shad abundance is very heartening," said Nick DiPasquale, director of the bay program, a federal-state "partnership" working to restore the nation's largest estuary.

DiPasquale called shad "an important indicator of ecosystem health." He attributed their resurgence in certain rivers to commercial fishing bans and improvements in water quality and fish habitat. Where shad numbers are lagging, he said, dams are often to blame.

Estimates of American shad baywide have increased from 11 percent of their restoration goal in 2000 to 44 percent last year, officials said. The improvement was driven largely by gains in the Potomac, which surpassed its target in 2011, and in the Rappahannock, which reached its goal last year.

Shad spend their adult lives roaming the Atlantic Ocean and migrate into freshwater rivers and streams to spawn. They once were the most valuable catch in the Chesapeake region, with vast numbers netted as they made their annual spawning runs up the bay's rivers. During the Revolutionary War, historians say, shad fed George Washington's troops in Pennsylvania after the harsh winter of 1778. The fish and their eggs, or roe, were once popular springtime fare throughout the bay region.

But the catch dwindled through the centuries because of pollution, overfishing and the construction of dams that blocked them from their spawning grounds. By 1980, shad had become so scarce in Maryland the state banned commercial harvests of them. Similar bans were enacted on the Potomac in 1982 and in Virginia in 1994.

Despite such protections, the fish did not bounce back quickly, and shad in other East Coast rivers have since declined as well. Experts have suggested part of their problem may stem from oceangoing trawlers netting them as unintentional "bycatch" while pursuing other fish.

States have tried to assist natural recovery by stocking millions of hatchery-reared shad.

Efforts have been made to restore spawning habitat for shad and other migratory fish. Some old unused dams have been removed, while fish "lifts" or ramps have been installed at others. More than 2,500 miles of rivers and streams have been reopened.

The fish passages have yielded mixed results to date, however.

A lift installed in 1997 at Conowingo dam on the lower Susquehanna seemed to be working at first, helping nearly 200,000 spawning shad upriver in 2001. Shad traffic declined after that, though, and hit an all-time low of 10,000 last year. And only eight shad made it all the way past the four dams on the lower Susquehanna.

This year's Susquehanna shad run has only recently begun, so it's hard to tell if it will fare any better than last year's.  As of earlier this week, the Conowingo fish lift had helped 4,465 American shad upriver, according to Exelon Corp., the operator of the hydroelectric dam there.