In the spring, shad swarm up rivers and streams all along the Atlantic Coast to spawn. After laying their eggs, the adults return to the ocean and spend the summer feeding on plankton off the coasts of Maine and Canada.
Issue with striped bass
Striped bass grow to three times the size of shad and eat just about anything. Like shad, they were nearly eliminated by overfishing, but a ban on catching them in Maryland and elsewhere in the late 1980s helped their numbers rebound, according to the state Department of Natural Resources.
Dale Weinrich, manager of the finfish program at the agency, said the rising numbers of striped bass, catfish and other predators probably are eating American shad.
But he said that's only part of the picture - and he doubts that's the main reason for the shad's recent drop. He noted that shad and bass coexisted in abundance for thousands of years before people messed up the ecological balance with pollution, dams and overfishing.
A more recent factor in the shad decline might be excessive fishing for them in the Atlantic Ocean, Weinrich suggested.
Despite a ban on targeting shad by fishing boats in many U.S. states, he said he suspects that fishermen off Canada or elsewhere in the Atlantic might be netting too many shad.
"Someone is perhaps targeting the shad for fishing," said Weinrich. Or fishermen pursuing other species might be catching shad in their nets accidentally, he said. "But once you get them in a net, they're dead."
Robbins, of the marine fisheries commission, concurred that striped bass are probably playing a role in the falling shad numbers, along with other factors, including water pollution, development and dams.
Conowingo fish lift
The fish lift at Conowingo Dam was built at a cost of $15 million more than a decade ago, after the U.S. Fish and Wildlife Service sued the dam's owners for blocking the shad's migration upriver. At first, it worked well.
The number of fish lifted over the dam by an elevator-like mechanism rose from 37,516 in 1996 to 193,574 in 2001.
But since then, it has been falling, to 56,000 in 2006, 29,000 last year, and about 16,000 so far this year, according to the federal agency and the dam's operators.
Fishermen along the base of the dam said Friday that they've noted the decline. But they said a less tasty kind of shad - called hickory shad, which are smaller and darker - remain plentiful.
