On Comeback Trail

September 10, 1995|By Timothy B. Wheeler | Timothy B. Wheeler,Sun Staff Writer

SELBY'S LANDING -- With a silvery flash, a stream of water bearing thousands of young American shad poured into the murky Patuxent River from the back of a power company truck.

The 2-inch fingerlings, spawned in a state hatchery and reared in tanks at a power plant nearby, are beginning an odyssey that will take them thousands of miles and at least three years before they return -- if they return.

State biologists are trying to give a boost to a battered species, relying on biotechnology and a power company's help to restore shad to a river that hasn't seen the once-abundant fish since the 1960s. If successful on the Patuxent, the state's efforts could replenish the rest of the Chesapeake Bay with a fish that once rivaled rockfish in the public's affections.

The juvenile shad released Thursday at a boat ramp in Prince George's County join more than 700,000 other newly hatched shad that have been stocked in the river in the past three years.

"We don't know, but we hope we'll get a robust spawning run in five to seven years," said Benjamin Florence, hatcheries director for the Maryland Department of Natural Resources.

The bony but tasty shad was once a staple on Marylanders' tables. But they were nearly wiped out by decades of overfishing and dams blocking their spawning rivers, prompting a state fishing moratorium in 1980.

Shad have been gradually returning to the bay since then, aided by more than $25 million worth of stocking in the Susquehanna River and construction of fish lifts and ladders to help the migratory fish swim past dams blocking their spawning runs. This year, state biologists tallied about 330,000 shad in the upper bay, the largest number found there since the moratorium but still well below the millions that populated the bay historically.

The fish also remain scarce elsewhere in the bay, so Maryland has begun stocking two other rivers, the Patuxent and the Nanticoke. For the Patuxent, biologists are using shad captured in the Susquehanna, since there were none to be found locally.

Using artificial spawning techniques developed by the University Maryland's biotechnology experts, state biologists this year got 4 million eggs out of 99 shad taken from a fish lift at Conowingo Dam on the Susquehanna.

In a process called "natural spawning," the biologists injected a hormone into the fish, triggering maturation of their eggs within a few days so that they could be fertilized in tanks at the state's Joseph Manning hatchery near Brandywine.

Conventional hatchery methods, in which ripe eggs are manually stripped from spawning females that have been captured, would not have produced nearly as many young and would have killed the adult fish.

"In two years, we've gone from being just experimental to having production," said Brian Richardson, a state fisheries biologist.

The 4 million eggs produced this year by the new technique yielded more than 900,000 tiny shad larvae, a third of which were released into the Patuxent in the spring.

The rest went to Potomac Electric Power Co., which raised them this summer in circular tanks at the utility's Chalk Point coal-fired power plant on the banks of the Patuxent.

The company built its hatchery in the 1980s to help restore striped bass, or rockfish. But with rockfish now declared recovered, the utility is converting its "aquaculture center" to help rebuild the bay's shad population, said Paul M. Willenborg, who runs the facility for Pepco.

The young fish stocked in the river appear to be surviving. Biologists checking the river this summer caught 300 juvenile shad in their nets, the first found in the Patuxent in 35 years, said Steven P. Minkkinen, a fisheries biologist working on the restoration effort.

Fish that have been reared in hatcheries are either tagged or chemically "marked," and the fish detected in the Patuxent appear to be stocked shad that have survived.

William Goldsborough, fisheries scientist for the Chesapeake Bay Foundation, said that the hatchery spawning techniques developed by Maryland's Department of Natural Resources hold promise for restoring shad, which are declining or barely holding their own in many East Coast rivers.

The juvenile shad released into the Patuxent this week will spend a few more weeks feeding and growing, then begin migrating down the bay to the ocean when the water cools in the fall. The young fish will join shad spawned in other rivers from New England to the Carolinas. They will spend the next three to six years roaming offshore before returning to the Patuxent to spawn.

State biologists say they hope to see hatchery-reared shad stocked in the river in 1993 return to spawn next spring.

Even if they do, it may be years before the bay's shad are reproducing enough to sustain themselves, state biologists say. Nearly 90 percent of the fish at the Conowingo Dam in the spring came from a hatchery, and biologists say that despite years of hatchery stockings, reproduction appears to be low.

Biologists believe that shad may need to reach a "critical mass" before they can spawn successfully. Research indicates males and females must be numerous -- how numerous, no one knows -- before shad will procreate. The shad brought to the hatchery had to be crowded into tanks to get good egg production, Mr. Minkkinen said, and the same may be true in rivers like the Patuxent and the Susquehanna. "We need to get to the point where there's enough adult spawners in the river to have good reproduction," he said.

But the state plans to expand its hatchery, and Mr. Florence said he hopes to be able to produce 10 million young shad soon. "When we get the ability to stock 10 to 15 million fish, we're going to have significant impact," he said.

Once enough fish are there to reproduce on their own, the hatchery effort can be shifted to focus on other depleted species, biologists say.

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