A March 2011 fish kill of thousands of gizzard shad in the Milwaukee Harbor ship canals was caused by the fish virus viral hemorrhagic septicemia, or VHS, according to results released March 31 from the Wisconsin Veterinary Diagnostic Laboratory in Madison.

The finding represents the first time VHS has been detected in Wisconsin's waters of Lake Michigan since 2008, and the first time gizzard shad have tested positive for VHS in Wisconsin, according to Sue Marcquenski, Department of Natural Resources fish health specialist.

VHS, which can infect several dozen different native fish species and cause them to bleed to death, does not affect humans. The first detection of the virus was in the Lake Winnebago system in 2007, and also in Wisconsin's waters of Lake Michigan that same year. The virus was confirmed in Lake Superior in 2010.

The Milwaukee Harbor canals fish kill started the week of March 14 and by March 18, involved several thousand fish. Dead and dying gizzard shad were collected and necropsied on March 22 and submitted to the Madison laboratory for testing.

For more information on viral hemorrhagic septicemia (VHS) and how to prevent its spread visit: http://dnr.wi.gov/fish/vhs/

source: Wisconsin Department of Natural Resources