Viral Hemorrhagic Septicemia (VHS)

VHS is a virus that has been found in the Great Lakes from 2003 to present.  This virus causes fish to hemorrhage and death is usually caused from internal organ failure. All five Great lakes are currently infected with VHS.  Fish infected with VHS can die in the thousands and it effects a wide variety of species.  A few species involved in large kills include muskies, yellow perch, and bluegills. Several other species have been infected but there has not had large die offs. Some of these include Chinook salmon, walleye, smallmouth bass, northern pike, channel catfish, lake trout, and rainbow/steelhead trout.  Over twenty-five Great Lakes native species are infected by VHS.  Photos below are of different species of shad infected with VHS. 



Photo: Andy Noyes, Vermont Fish and Wildlife Dept.



Photo: Mohamed Faisal, Ph.D., Michigan State University

Different strains of VHS are found throughout the world infecting both fresh and salt water fish.  The strain in the Great Lakes is believed to have originated in Maritime Providences in Canada.  Original sources into the Great Lakes could have been from untreated ballast water, or infected migratory fish.  VHS has also been found in some inland lakes.  The following map shows the infected areas within the United States Great Lakes Region.  Canada data is not included in this map.

Map: U.S. Department of Agriculture (USDA) Animal and Plant Inspection Service (APHIS) Veterinary Services (VS) Center for Epidemiology and Animal Health (CEAH)

One way this virus is spread through through fish waste it can survive in the water outside of the host for several weeks.  Large die offs usually occur during spawning season when populations are more concentrated.  Although this disease has made its way throughout the Great Lakes there is hope.  Biologists believe like most viruses this one will run its course.  Fish that survive VHS and their offspring appear to be more resistant to the virus.  This leads me to believe that immunity to VHS is beginning to appear in the population.  Please watch this educational video about VHS put out by the USDA and the APHIS. (Animal Plant Health Inspection Service) 
 

References:
http://ftp.great-lakes.net/envt/flora-fauna/invasive/pdf/vhs_glc_factsheet_2011.pdf
http://www.seagrant.wisc.edu/home/Default.aspx?tabid=531
http://www.vtfishandwildlife.com/library/factsheets/fisheries/fish_health/Viral%20Hemorrhagic%20Septicemia%20Virus/Andy%20Noyes%20-%20VHS%20-%20Gizzard%20Shad.jpg