Shad resurgence going swimmingly

Rivers: Fish released by the state years ago are returning to spawn on their own.

April 25, 2002|By Heather Dewar | Heather Dewar,SUN STAFF

One of the broken links in the Chesapeake Bay's chain of life is being mended in the coffee-brown water of the upper Patuxent River.

The shadbushes are blooming along the forested banks near Davidsonville. And beneath the water's surface, the shad are running, returning to spawn in the river's headwaters from points as far-flung as the Bay of Fundy.

The bay's once-huge spring shad runs were nearly driven to extinction in the 1970s, forcing state officials to shut down the commercial fishery.

But more than two decades later, the fish are slowly returning to at least three local rivers, with the help of state fishery managers who are stocking the waterways with as many as 23 million juvenile fish each year.

State biologists say the bay's two main varieties, hickory shad and American shad, are breeding naturally in the Patuxent and the Choptank, where the reintroduction of hatchery-bred fish began in the mid-1990s. And this year, for the first time, hickory shad released as youngsters in the Nanticoke River in 1999 are returning there to spawn.

"We're seeing more and more natural reproduction every year, which is a very good sign," said Steven Minkkinen, hatcheries manager for the Department of Natural Resources, as he and three co-workers traveled by motor boat to one of the species' spawning grounds on the narrow, twisting upper Patuxent. "Hopefully one day we're going to stop stocking here. The hatchery fish won't be needed anymore."

In Colonial times, shad were "the most important food fish on the East Coast," said Minkkinen. "Every cabin had its barrel of salted shad. George Washington had a fishery right in front of his house" at Mount Vernon, on the Potomac River.

The colonists took advantage of the shad's complicated life cycle. Born in fresh water, young shad gradually move into the bay in the fall and then out to sea. Three or four years later, as adults, they travel hundreds of miles to spawn in the river where they were born - or, in the case of hatchery fish, where they were set free.

The hickory shad, with jutting jaws and a faint purple sheen on their green backs, arrive in early April when the shadbushes' white blossoms glow on leafless limbs. Cued by water temperatures of 58 to 64 degrees, they lay free-floating eggs upstream.

In late April and May, slightly warmer water brings the American shad, distinguished from its kin by a golden-pink iridescence and larger size, up to 30 inches.

Migration blocked

So many migrating shad were caught in fishermen's nets or blocked by dams from the spawning grounds that by 1980, the state had imposed moratoriums on commercial fishing for both species. There is a catch-and-release recreational fishery.

The bay states are removing dams or building migration routes around them on 18 rivers. Shad runs have grown rapidly on the Susquehanna, after a $60 million investment in fish ladders and a decade's worth of hatchery stocking made it possible for the fish to travel the river's full length, 440 miles upstream to Binghamton, N.Y.

On some unobstructed rivers, experts hoped the spawning runs would return on their own.

That didn't happen. These rivers were so heavily fished that too few survivors remained, Minkkinen said. So the restocking effort using hatchery-raised shad began on the Patuxent in 1994.

Telltale ear bones

To mark the three rivers' hatchery stocks, biologists rely on a unique property of the fishes' otoliths, or ear bones.

Like trees, the tiny inner-ear bones lay down growth rings - once a day when the fish are young - which can be marked by immersing the small fry in an antibiotic solution. By dunking the fish intended for each river on slightly different schedules, the biologists create distinctive patterns in the otoliths. Visible only under a microscope in ultraviolet light, the patterns distinguish hatchery fish from wild ones and tell which river the hatchery fish came from.

In spring, the biologists cruise the rivers in an 18-foot boat with a pair of specially designed outriggers, trailing pinwheels of steel wires into the water. The electrically charged wires attract and stun the fish, allowing researchers to count them. On each cruise, up to 30 shad are netted, iced and taken to the lab for analysis of their ear bones.

Gliding down the shallow, winding Patuxent south of Queen Ann's Bridge on a warm April afternoon, biologist Brian Richardson steered over storm-drowned trees while Minkkinen and biologist Chuck Stence used long-handled nets to scoop up stunned and struggling shad.

A bald eagle and a great blue heron soared overhead. A kingfisher darted from bank to bank, and warblers sang amid the new green leaves of water oaks, tulip poplars and dogwoods.

In about an hour, the crew counted nearly 200 migrating shad. "When we started [counting returning shad] in 1999, we probably didn't see this many fish in a year," Minkkinen said.

It will be late summer before the scientists examine the fish. But past studies show a steady rise in the number of wild-bred fish in the Patuxent, reaching 11 percent of last year's sample.

Success will come when three-quarters of the rivers' shad are wild-bred. At that point, Minkkinen said, no more hatchery fish will be introduced.

Someday, the commercial fishery could be revived and "shad plankings," the Chesapeake's traditional spring feasts, could rely on local fish instead of out-of-state imports.

"I don't see any reason why not," Minkkenen said. The fish are a little bony for modern tastes, he said, but "I like them smoked."

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