State officials said yesterday that preliminary tests have not identified what killed 10,000 fish in a Somerset County waterway that drains into the Pocomoke River near Shelltown.
The local waterman who alerted state officials to the kill said he suspects it is connected to the mysterious lesions that have been found on fish in the Pocomoke since last fall. Such lesions that are now turning up in other Chesapeake Bay tributaries such as the Susquehanna, Magothy and Choptank rivers.
The Maryland Department of the Environment, which is leading the investigation of the Sunday die-off, has collected samples of water and fish tissue for analysis and expects results within a week or so, said MDE spokesman Quentin Banks. There was no indication of a threat to human health or that the kill was caused by pfiesteria piscicida, the deadly algae linked to large fish kills in North Carolina, he said.
"We don't think that's what it is, but we're not ruling anything out," Banks said.
Ray Maddox, who fishes the Pocomoke regularly, said, "A lot of the fish that were dead in the water had lesions on them."
Most of the dead fish were carp, scientists said, but there were also catfish, mud shad, croaker, white perch and sunfish.
Maddox called the environmental agency's local representative, Yvonne Lawson, Sunday night after seeing the dead fish in a tidal ditch between two farms and in Broughton Creek, which links the ditch with the Pocomoke.
Preliminary testing yesterday found a heavy concentration of pond algae but no other clues, said Charles Poukish, who coordinates fish-kill investigations.
"They all died very quickly," Poukish said, noting that such fish kills occur once or twice a year. "By Monday morning, it was over," he said.
Poukish said the ditch where the kill occurred was "highly enriched" with nutrients, which typically come from sewage or farm runoff of manure or fertilizer. Tests have shown nothing more than abnormally high levels of two common types of pond algae, which are not toxic to humans.
The kill occurred less than a week after state scientists intensified their search for the reason that lesions have been turning up on fish caught in the Pocomoke since last fall. Local watermen have expressed concern for their livelihoods and for their health.
JoAnn Burkholder, a pfiesteria expert at North Carolina State University, found the fish-killing algae in water samples collected from the Pocomoke early last month, and she suggested that as a possible cause of the lesions.
Pfiesteria is a shape-shifting microorganism that first attacks the nervous system of a fish and then consumes its flesh. It also has been linked in North Carolina with flulike illnesses and sores among aquatic researchers and divers.
The organism was found in the Chesapeake several years ago, but state officials say they have yet to find any evidence of it in the Pocomoke.
"We have no indication that pfiesteria was involved," Poukish said. "The lesions were not real extensive [on the dead fish]. But we don't know what this is."
Water and sediment samples have been sent to laboratories in North Carolina and Florida, which will test for pfiesteria. Maryland does not have the equipment or the trained staff to run those tests.
Pub Date: 6/18/97