PRINCESS ANNE -- Tony Mazzaccaro last week peered through a microscope lens, searching for an elusive killer. "I just don't see it," he said. "Looks like I won't have to nuke the pond after all."
Mazzaccaro, owner of the Hyrock fish farm by the Manokin River in Somerset County, was looking for a microorganism that might have been responsible for killing 8,000 of his hybrid striped bass in early August. A year earlier, a microbe may have killed 23,000 of his farm's adult bass.
Both times, he had to "nuke" several of his fish ponds -- treat them with chemicals to clean them of harmful organisms.
Mazzaccaro's ponds are filled with water from Goose Creek, at the mouth of the Manokin River in Somerset County.
The state closed portions of, the Pocomoke River in Somerset County and the Chicamacomico River in Dorchester County, along with Kings Creek, a Manokin tributary, this summer after fish and people were apparently sickened by a sometimes-toxic microorganism, Pfiesteria piscicida.
After the August fish kill at Hyrock, water tests were inconclusive as to whether it was the work of Pfiesteria. Experts say that kill likely was the work of another harmful microbe.
But after the 1996 incident, Pfiesteria was found in Mazzaccaro's ponds. Experts still differ on whether that microbe or another one killed his fish at that time.
Now Pfiesteria and other harmful microorganisms may be casting a broader shadow over the aquaculture industry, which has been considered a growing and bright business in Maryland.
Nationwide, aquaculture is a billion-dollar industry. In Maryland, it has been hot -- growing from nearly nothing 10 years ago to $20 million in sales last year.
Maryland officials have been aggressively promoting aquaculture because the state has a favorable climate, location and, most important, abundant water resources, said Roy Castle, chief of the aquaculture program for the state Department of Agriculture.
"There's just a tremendous market for it," Castle said. "The state's located within eight hours of one-third of the country's population. And they eat a lot of seafood."
But Pfiesteria now has thrown some in the industry for a loop.
"With the Pfiesteria scare, the seafood market has dropped in half," said Richard Pelz, of St. Mary's County, president of the Maryland Aquaculture Association.
Pelz is hopeful, however, that the Pfiesteria problem may turn out to be a boon for aquaculture. "When consumers return," he said, "they can get a healthy product from us -- from water that's not affected."
In Maryland, the largest aquaculture sector is tilapia, a freshwater fish grown indoors using well water -- where Pfiesteria has not been found.
Maryland fish farmers raise about 800,000 pounds of tilapia, 75 percent of the state's farmed fish, with much sold out of state to Asian consumers.
But for fish farmers dependent on waterways, the story could be different.
In Maryland, many fish farmers raise bass, trout and other species in pens in waterways. Others raise and harvest oysters, scallops and clams.
At Hyrock Farm, where Mazzaccaro has been fish farming since 1993, he now not only has to contend with microorganisms threatening his crops but also lowered demand from worried consumers. "It's really going to hurt me," he said.
Every morning during the summer, Mazzaccaro awakens at 5: 30 to check his ponds for oxygen levels -- the most critical indicator for fish health. Then he loads a device full of feed pellets and drives around his 37 acres spraying them onto his 10 ponds.
Because he can't use well water -- there are no large aquifers nearby -- he pumps water from Goose Creek, only a few miles from Kings Creek, the Manokin tributary where Pfiesteria is believed responsible for a fish kill Sept. 10.
To prevent future kills, Mazzaccaro -- thanks to a grant from the University of Maryland -- has purchased a water purifier, which he will install in December. It essentially will sterilize Goose Creek's brackish water as it goes into his ponds.
"If this doesn't work," Mazzaccaro said, "then I don't recommend this type of business to anyone."
Another fish farmer -- Bill Voorhies, of Wittman in Talbot County, who raises about 1,200 bass in four pens along Harris Creek, a tributary of the Choptank River -- doesn't believe Pfiesteria will hurt his business but the news media's focus may.
"If my bass get Pfiesteria," he said, "then they're going to have to evacuate the whole state. Everything gets blown so out of proportion."
Pub Date: 9/21/97