The report this past summer that the Maryland Darter, the only animal, bird or fish found only in this state, has disappeared from its last known home in Susquehanna State Park was deeply distressing. Frostburg State University biologist Richard Raesly, who searched for the diminutive member of the perch family in Deer Creek, still hopes it will turn up again. After all, as he says, rare species have been thought extinct before.
Still, other fish in the 171-mile Deer Creek watershed near Havre de Grace have been disappearing as well. Five miles upstream from where Maryland Darters were last seen, Mr. Raesly collected 45 fish of 10 species last year. Four years earlier, he netted 695 fish from two dozen species. The Maryland Darter may still be around -- three other kinds turned up where Mr. Raesly was looking for it -- but its decline from the populations found in Swan Creek and its Gashey's Run tributary near Aberdeen early in this century is surely a harbinger of the troubles bedeviling the watershed.
Putting the story on "Unsolved Mysteries" might raise public awareness, but the main culprit, development, left footprints all around. Farmers along Deer Creek have been persuaded to leave uncultivated buffers on the banks, and building restrictions have kept growth down. Yet Swan Creek, where the darter was first found, is muddy with runoff. Deer Creek, cleaner looking, has high levels of nitrates and chlorides. The suspects: fertilizer from less-conscientious farming and treated wastewater discharged upstream. In addition, silt from spring runoff may be smothering the darters' eggs.