A mystery virus is affecting populations of Largemouth bass, Micropterus salmoides, across the USA.
According to the Detroit Free Press, the virus is "suspiciously similar" to one found in tropical fish. The paper speculates that this seems more likely because the mystery virus was first found in Lake Weir, Florida, in 1991, an area rich in tropical fish farms and importers.
The disease has now spread to 17 states, moving as far north as Michigan.
Gary Whelan, Fisheries Production Manager for the Department of Natural Resources, told the Detroit Free Press: "What has us somewhat concerned is that we don't know how the virus works on the northern subspecies or in northern waters.
"Wherever there has been an outbreak it has killed more than 10% of the Largemouth bass population. It first showed up in Lake George in 2000, and now we've confirmed it in 15 other lakes."