Success against virus in fish

Researchers with the state Department of Environmental Conservation and Cornell University, Ithaca, have found that an iodine disinfectant solution can protect walleye eggs from a deadly fish disease if the virus is introduced from the outside.

Stephen R. LaPan, Lake Ontario unit leader for DEC in Cape Vincent, said this means they may be able to protect the fish from viral hemorrhagic septicemia.

"If there is external introduction, we can kill it," he said.

Several DEC fisheries pump water from the St. Lawrence River, which has multiple species known to be infected with VHS.

During this year's research, the scientists had a control group in which VHS was introduced into the water around walleye eggs and not treated. A second group of eggs had the same VHS treatment but was treated with iodophore, an iodine solution. Those eggs hatched uninfected, while eggs from the control group hatched with infected fish.

"We've moved the ball a little bit further in the research," Mr. LaPan said. "But there's still a lot we don't know about the virus."

Future research will be necessary to determine whether the mother fish transmits the disease to eggs directly, called vertical transmission, and whether iodophore still will be effective.

"These are very difficult experiments to do," Mr. LaPan said. "Even if the virus is inside the egg, we're hopeful the iodine solution can still kill the virus."

Last year, the researchers found that treating the eggs with the iodine solution did not hurt the young fish.

Mr. LaPan said the department has seen no fish kills from VHS this year, but that should not be misinterpreted as the virus disappearing.

"It's something different about environmental conditions this year — that would be my guess," he said.

But now, there is a possibility DEC could breed uninfected fish.

"If the virus isn't vertically transmitted, we're pretty confident we can kill the virus," Mr. LaPan said. "We can have disease-free fish."