The Maryland darter is missing, and Richard Raesly fears it may be lost for good.
One of the rarest fish in the world -- and the only one that is unique to Maryland -- the elusive little member of the perch family has not been seen for three years now, despite an intensive state-funded search of its last known whereabouts in Deer Creek in Harford County.
Raesly's latest look-see last week came up empty-handed. The Frostburg State University biologist and his two assistants left few stones unturned in a 100-yard stretch where the stream flows through Susquehanna State Park near Havre de Grace.
The shallow riffle is the only place the fish have been found since the early 1960s.
Standing knee-deep in the clear, fast-flowing stream, Raesly flipped over rocks and kicked up silt and sand from the bottom while two helpers stretched out a seine net just downstream to capture any fish that might be flushed from hiding.
They almost netted a swimsuit-clad couple floating downstream on truck tire inner tubes.
"What are you catching?" the woman asked with a smile.
After two hours, the search party had netted 150 small fish from a dozen different species, including three other kinds of darters. But no Maryland darters.
"If they were here, chances are you would have gotten one or two," Raesly said.
Raesly may have been the last person to see the fish alive.
In August 1988, wearing a diving mask and snorkel, Raesly spotted the distinctive dark V-shaped saddle and blotch markings of two tannish-brown Maryland darters lurking in the riffle, nearly two miles upstream from where the creek empties into the Susquehanna River.
Since then, however, he has been searching without success, even when seining or using electrofishing gear that temporarily stuns fish, making it easier to spot them.
"Rare species, if you don't find them for a year or two and you say they're extinct, they have a way of coming back," Raesly said.
"But at this point the outlook is very poor indeed," he added, "and if I don't get any throughout the rest of this summer and into the next spring, I think I would have to say they have probably gone extinct."
"It's looking like it is extinct," acknowledged Andrew Moser, endangered species biologist for the U.S. Fish and Wildlife Service in Annapolis. "The only question is: Have we looked hard enough to be sure?"
Moser says he is not ready to give up on the fish until Raesly's search is finished and a panel of fisheries experts has decided whether anything more can be done to find it.
If the Maryland darter is extinct, the state will have lost the only animal, bird or fish that has been found only in Maryland.
The unique nature of the Maryland darter (scientific alias: Etheostoma sellare) is little appreciated by the public because the fish is so rare that only a handful of people have seen it.
But biologists say its loss is a tragedy, nonetheless.
"Like every other part of our natural heritage, it's one more thing that our children won't have as part of their environment," Raesly said.
"It's just one fish, but it's part of the total diversity of life that's out there, and it's not the only thing that's being lost," Moser said. "We're losing species all over the world."
The Maryland darter is one of 121 animals and 497 plants officially listed as endangered or threatened with disappearance from Maryland. Twenty-one of those animals and 184 plants already have vanished from the state, though they may still be found elsewhere.
Though it may once have been abundant, the three-inch Maryland darter has been found in only two other places.
The species was "discovered" nearby in 1912 in Swan Creek, near Aberdeen.
Fifty years passed before the fish was reported again, this time in Gashey's Run, a tributary of Swan Creek. It hasn't been seen in either stream since 1963, and Swan Creek is showing the effects of heavy development in its watershed.
"It's a big mudhole there," Raesly said. "It doesn't look like any could live there now."
Apparently limited to Deer Creek since 1963, the Maryland darter has been listed as endangered by the federal government since 1967, and the agency's "recovery plan" for the species still envisions the fish population rebounding one day, Moser said.
"The actual goal was to maintain the population that was there, and we haven't even succeeded in that," he said.
Federal and state officials say they have tried to save the little darter. Farmers and other landowners along Deer Creek were asked to refrain from disturbing the shore, and many signed easements at the behest of the Deer Creek Watershed Association. Harford County also restricted development in the area.
"But it was probably too late for the Maryland darter," said Rodney Bartgis, an ecologist with the Natural Heritage program of the state Department of Natural Resources, protector of endangered species.
Indeed, well-meaning scientists may have contributed to the darter's demise. They snatched more than 100 from the Deer Creek riffle for study in 1965, and since then the fish have never been spotted in such numbers.
"A collection of that scale could easily have reduced the population to the point it could not recover," Bartgis said.
Until recently, though, at least a few fish were seen every year or two when searchers donned diving masks and snorkels to poke under submerged rocks in the riffle.
Biologists are not sure why the Maryland darter has vanished. Deer Creek looks clean enough, and it is still richer in aquatic life than many other streams.
But the fish's demise may be an early warning of a general decline in the 171-square mile Deer Creek watershed, which covers one-third of Harford County and stretches into Baltimore County and Pennsylvania.
The number and variety of all fish in the creek has plummeted in recent years, Raesly said. About five miles upstream from the Maryland darter's historic hangout, he said he found only 45 fish of 10 species in May 1990. Four years earlier, he collected 695 fish representing two dozen species in the same spot.
Water sampling has detected high levels of nitrates and chlorides in the creek, which Raesly said may be harming fish reproduction and survival.
Possible sources of those nutrients may be fertilizer running off farmland or treated wastewater discharged from sewage plants upstream.
While searching the creek last week, Raesly pointed out another problem -- a thin layer of tan silt covering the sandy bottom. He suggested that soil runoff in springtime could be smothering the Maryland darter's eggs, which scientists believe are laid on the stream bottom.
There has been relatively little development along Deer Creek, in part because of building restrictions imposed by the county and the state in an effort to save the Maryland darter. But more than half the land that drains into the creek is farmland. And although many farmers have agreed to leave grassy or forested buffers along the stream, not everyone is complying.
Biologists considered trying to save the Maryland darters by capturing some and breeding them in an aquarium. But by the time they thought of that, the fish were no longer around.
Marchant Hall, a member of the watershed association, says he hopes that county officials will act now on the groups' request for intensive water-quality monitoring of the creek, to find out what is happening to the fish.
Miller, the planner, says the darter's demise shows how "environmental quality is eroding. We're just nibbling away at it, and all of a sudden something is gone."