HAMILTON, Ind. -- A largemouth bass die-off at a Steuben County lake last August was not as severe as anglers feared.
Johnson Lake, a 17-acre natural lake north of Hamilton, still contains plenty of healthy bass, including many large ones, according to Indiana Department of Natural Resources (IDNR) fisheries biologists.
In mid-May, biologists captured 49 bass in 30 minutes of sampling during an electrofishing survey. The catch rate was typical for bass populations in most northeast Indiana lakes.
Nearly half of the bass were 14 inches or larger. The largest was 18.5 inches. Various age groups of bass were present, including several from last year's spawn.
"Although the die-off was disappointing, it was not devastating," said Neil Ledet, IDNR biologist.
Ledet said the bass die-off began in early August and was triggered by largemouth bass virus.
Presence of the virus was later confirmed from samples sent by Ledet to Purdue University's Animal Disease and Diagnostic Laboratory for testing.
The samples included bass that had recently died as well as healthy-looking ones.
Similar die-offs caused by largemouth bass virus have occurred at other Indiana lakes, including Steuben County's Lake George in 2000 and Hamilton Lake in 2001.
Bass populations in both lakes fully recovered, and the lakes remain popular among bass anglers.
"There is no reason to believe that Johnson Lake's bass population won't follow suit," Ledet said.
Although the origin of largemouth bass virus is not known, biologists think it is present in many area lakes. Bass appear to be more susceptible to it during periods of hot weather.
It has also been found in bluegills and crappies, but typically does not kill species other than bass.
"There is nothing that can be done to eradicate bass virus, but we want to document where it causes fish kills," Ledet said.
Anglers can help prevent the spread of the virus by properly disposing of unused bait and not transferring fish from one lake to another.
More information about largemouth bass virus is available at dnr.IN.gov/files/LMBV.pdf.