Back in the 1700s, one Potomac traveler remarked in amazement that shad were so abundant that "above 5,000 have been caught at one single haul of the seine." Jim Cummins has never seen 5,000 shad in a net-a score of fish is more typical-but he keeps working toward the day when the river again runs silver with migrating fish, as people say it once did.

Cummins, a biologist with the Interstate Commission on the Potomac River Basin, has surveyed shad on the river with a crew of watermen since 1995, as well as stripped eggs from captured females to help rebuild populations.

The Potomac, in a sense, is the nursery for other rivers around the Bay. Stocking efforts in the Susquehanna, Patuxent, Choptank, Nanticoke and Rappahannock rivers all use Potomac eggs. Five percent of the larvae sent to hatcheries for those rivers is returned to the Potomac to replace those removed.

While shad are at record lows along most of the East Coast, the Potomac is one of the few rivers where spawning numbers have increased during the last decade, although Cummins reported that this year's run was not as strong as expected. "It was down both in the number of fry that we were able to stock, and the adults we were able to count," he said. "This year's yo-yo-like spring weather, especially the near record heat in late April, at the peak of the run, was detrimental to both egg viability and spawning behavior."

Shad are an anadromous species; they spend most of their lives in the ocean, but return to their natal freshwater rivers to spawn. Shad numbers are down coastwide because they were overfished decades ago and because dams and other structures block migrations to historic spawning grounds. When in the ocean, they can fall victim to fisheries targeting other species.

Shad are a grazer; their mouths contains "gill rakers," a net-like structure that allows them to swim with their mouths open and collect plankton. Another of their problems today is not what they eat, but how many things eat them. Nonnative predators such as blue catfish now intercept shad on their spawning runs up tributaries, and minnows will consume their eggs before they hatch. Historically, shad overcame such problems with their huge numbers.

Numbers have been so low for so long that Cummins works with others, such as Living Classrooms of the National Capital Region, to remind a new generation of what the resource was once like. Living Classrooms runs a program in which 4,000 students from 53 schools in the metropolitan Washington, D.C. region raise shad in their classrooms as they learn about its role in rivers and efforts to restore the fish.

A handful of those students are selected to accompany Cummins and the watermen on each survey trip. There's no shortage of enthusiasm. "I've had to turn away a lot of the volunteers that want to come out," he said. They all hope to someday see the river run silver again.