Biologists around the watershed reported mixed results for this year's American shad run. A quirky cold snap in the middle of the spring spawning run hampered egg collection efforts, so overall stocking was down from last year, although officials reported that they still met stocking goals on most rivers.

The cold snap also put the brakes on fish migration for about three weeks, making it difficult to gauge the strength of this year's spawning run. "It's hard to get a handle on what the run really was like because of that," said Dean Fowler, a fisheries biologist with the Virginia Department of Game and Inland Fisheries.

Overall, biologists said the run appeared average and were optimistic that the region's shad restoration efforts-which date to the early 1990s in most rivers-were slowly showing results.

The main exception was the Susquehanna, where restoration work has been under way since the 1970s. Efforts on the river have been plagued by fish passage and stocking problems in recent years. The dismal number of fish counted this spring at the Conowingo Dam: 25,464-is the lowest since 1993.

Shad are an anadromous fish, meaning they live most of their lives in the ocean but return to their native rivers to spawn, often swimming hundreds of miles upstream before releasing their eggs. They once numbered in the tens of millions during their spring spawning runs.

Shad populations along the East Coast have been at near-record lows in recent decades, the result overfishing, pollution and the closure of historic spawning areas by dams and other obstacles. The sharp drop resulted in a moratorium on shad fishing since 1980 in Maryland, 1982 on the Potomac River and 1994 in Virginia. Also, the Atlantic States Marine Fisheries Commission, which manages migratory fish along the East Coast, has ended shad fishing in the ocean.

Because they link upstream areas with the Chesapeake, shad restoration has been a priority for the Bay Program.

State and federal agencies, nonprofit organizations, Native American tribes and others throughout the watershed in recent years have not only stocked hundreds of millions of shad, but worked to remove dams and build fish passages to reopen areas long closed to the migratory fish.

As a result, shad populations in many rivers have been trending up, although at a fraction of their historic levels.

Shad are doing best on the Potomac which has maintained the healthiest shad population in the Chesapeake-and along the entire East Coast-and supplies most of the eggs for stocking efforts in other rivers.

Surveys on the river this spring captured 30.9 shad per net-the third best in the 13-year-old survey, said Jim Cummins, a biologist with the Interstate Commission on the Potomac River Basin. The average is 22.8, but Cummins noted that runs have nearly doubled since the first five years of the survey, when the average was just 14.8.

"We're sitting comfortably, but I want to see more," he said. "I want to see the river loaded up, looking silver again. But we haven't gotten there yet."

In Virginia, biologists stocked 12.5 million shad, down from 16 million last year, but well above the state's stocking targets. Nearly 6.5 million went into the James River system, including its tributaries: the Appomattox, Rivanna and Slate. Almost 5.5 million went into the Rappahannock River above Fredericksburg-where the Embry Dam was removed in 2004-and in a tributary, the Hazel.

The remainder of the larvae went into the Potomac and Pamunkey rivers to replace spawning fish taken for the hatchery program.

While this year's stocking effort was strong, Fowler said he was concerned about the survival of the fish. Studies conducted by the department indicate that larvae survival is poor when river flows are below normal in June and July, as was the case this year.

"We were hoping for a normal flow this summer," he said. "It's very disappointing. We worked very hard this spring to try to compensate for the weird weather and we ended up exceeding our quotas. But with Mother Nature doing what she's done, it doesn't look good for this year class."

Nonetheless, biologists see evidence that the James River stocking program, launched in 1994, is paying off. Until 2003, hatchery-reared fish accounted for 78-91 percent of the spawning population in the river.

But in 2006, only 44 percent of the fish sampled originated from the hatchery. The rest were offspring of hatchery-reared fish that had successfully returned to spawn. "That's only one year," Fowler cautioned. "Nonetheless, we'd like to see that happening."

The goal of all the hatchery programs is to eventually establish populations that can maintain themselves without stocking.

In Maryland, stocking efforts were also down. Brian Richardson, a biologist with the Maryland Department of Natural Resources, said 1.6 million American shad were stocked in the Patuxent, Choptank and Nanticoke rivers, down from 3 million last year.

Still, shad runs appeared solid, especially on the Patuxent, where shad have been stocked since 1994. "I think we saw about what we expected," Richardson said. "It wasn't a huge run."

Delaware stocked 231,000 fish in the Nanticoke and two of its tributaries, Broad Creek and Deep Creek, said Mike Stangl, of the state's Department of Natural Resources and Environmental Control.

That was less than half of last year's 513,000. Stangl said stocking was hindered because returning fish were smaller, and appeared younger, than last year, so females had fewer eggs. Also, only 29 percent of the eggs were viable. "There was an obvious lack of larger females this year," he said.

The worst news was on the Susquehanna, where only 1.4 million were stocked, far below the river's 10 million goal. Much of this year's production was lost when water in the mountain stream feeding the hatchery turned acidic. "I think acid precipitation is finally getting to us," said Mike Hendricks, a biologist with the Pennsylvania Fish and Boat Commission.

Hatchery efforts have been plagued by a series of problems in recent years. The 10 million goal was met only once since 2000-in 2003, a year when the survival of stocked larvae was low because of bad weather conditions, Hendricks said.

Compounding the problem, few fish are making it through passages at four hydroelectric dams to reach spawning grounds, so little natural reproduction is taking place.

In the 1990s, the utilities owning the four dams-Conowingo, Holtwood, Safe Harbor and York Haven-invested tens of millions of dollars building fish passages. This year, only 192 shad made it past all four-the lowest since 2000, when the final passage was opened. The number of fish returning to the Conowingo Dam-the first dam encountered by migrating shad-has dropped steadily since hitting a recent high of 193,574 in 2001.

"We need to improve fish passage. That is clearly the missing link in terms of getting the fish restored," Hendricks said.

He said state and federal officials hope to negotiate new fish passage goals as dams come up for relicensing with the Federal Energy Regulatory Commission over the next decade. If each dam was able to pass at least 75 percent of the fish that get above the previous dam, biologists believe the long-term goal of getting 2 million shad upstream could eventually be met, Hendricks said.

While passage has generally been good at Conowingo and Safe Harbor, it has been poor at the other two dams. Changes are in the design stage at Holtwood that could improve shad passage.