Bass virus enters Michigan for first time

By MAUREEN O’HARA
Capital News Service
LANSING — As both an expert biologist and experienced fisherman, Ron Spitler is concerned with protecting Michigan fish populations from a widely spreading disease.
The largemouth bass virus was first detected in the fall of 2000 during an investigation of a big bass die-off in Lake George, located in Hillsdale County. The lake, located near the I-69 freeway on the Michigan-Indiana border, was the furthest north that the virus has ever been spotted.
“The simple truth is that there’s not a lot we can do about it,” Spitler said. “It’s just like a bad cold sweeping through the state.”
Although the virus is relatively new to Michigan, it was first detected in the southeastern part of the nation in 1995.
Large fish mortalities are one way of identifying the virus, but Department of Natural Resources fish pathologist John Hnath is quick to point out that they can die from several reasons. These include stressors, warm water temperature and heavy fishing pressure.
“The DNR cannot eradicate this virus or treat affected wild fish populations,” he said. “However, as we continue investigating this outbreak, we appreciate receiving reports of unusual fish mortalities.”
Alerting the fishing community is one of the main efforts behind identifying lakes that are contaminated with the virus. Hnath is focused on increasing awareness among many of the state’s tournaments, along with educating anglers about safety precautions.
“There’s no way to prevent the disease,” he said. “But we advise them to dry and clean their boats sufficiently, along with slowing down the rate at which they catch.”
In addition to informing anglers about the disease, department biologists are discussing the possibility of asking tournament sponsors to collect irregular-looking fish in order to be processed for signs of the virus.
Spitler echoed the department’s sentiments and is encouraging the Michigan BASS Federation members to follow the suggested changes during summer tournaments. He added that once a bass is about 14 inches long, man becomes its chief predator.
“While we do have a short bass season, we are recommending that tournaments shorten their days and try to reduce the holding time in live wells.”
Beginning this summer, the DNR will closely monitor 12 to 16 lakes to the east and west of Lake George. These waters may have never had mortalities, Hnath said, but the department wants to thoroughly check the area for any signs of the virus.
“The geographical distribution is quite interesting,” he said. “Up until now, it’s only been considered a warm water trend.”
Kelley Smith, DNR fisheries division chief, said that the Michigan BASS Federation will aid the area surveys to help protect the fish populations.
“This disease has never been this far north, and we still do not know how largemouth bass populations will be affected in Michigan’s lakes,” she said.
Hnath contends that the DNR is unsure how the virus is passed. Like a human infection, however, there are various possibilities.
“It could be transmitted by water, other fish or even birds,” he said. “And whether it’s been here or just come to the state remains speculative.”
Humans are not completely eliminated from the transmission, according to Hnath. Water sports that involve bringing boats from one body of water to another can also carry the virus.
The virus is not dangerous to humans, but the department recommends cooking the fish thoroughly.
Unlike other diseases, the largemouth bass virus may not be easy to identify in fish. Warning signs include lethargic movement and slow response to surrounding activity. Dying fish, on the other hand, may be seen near the surface of the water and have difficulty swimming upright.
© 2002, Capital News Service, Michigan State University School of Journalism