NEWVILLE – The koi herpes virus that’s expected to kill thousands of common carp has spread from Rock River to Lake Koshkonong, and will likely hit Janesville and Beloit in the next few weeks, a Wisconsin biologist said. It does not seem to cause the fish much distress and the fish will continue to swim and eat readily, but it is definitely unsightly. The development of a carp management strategy is a key component of the North Central CMA’s Native Fish Recovery Plan, which aims to increase the diversity and number of native fish in the Gunbower and lower Loddon systems, and lead to the establishment of a world-class Murray cod trophy fishery. Laura Stremick-Thompson, a fisheries biologist serving Dodge and Jefferson counties, said DNR began investigating the first die-off on July 21 in the state and federal waters of Horicon Marsh and Lake Sinissippi. In spite of the low variation between strains and crosses, there was a large genetic variation within strains and crosses. According to Rowan, the virus has subsided and the carp die-off is over for the most part. Typical herpesvirus particles were present in branchial epithelial cells, hepatocytes, and among circulating leukocytes.
These analyses demonstrated that the skin of the fish covering the fins and also the body is the major portal of entry for KHV in carp. The Piscine nodavirus of the genus Betanodavirus, genotype red-spotted grouper nervous necrosis virus (RGNNV) is predominantly involved. All the data obtained in the present study demonstrate that the skin, and not the gills, is the major portal of entry for KHV in carp.