Viral Hemorrhagic Septicemia (VHS) In New York
Viral hemorrhagic septicemia (VHS) virus is a serious pathogen of fresh and saltwater fish that is causing a disease issue in the Great Lakes region of the United States and Canada. VHS virus affects fish of all size and age ranges. It does not pose any threat to human health. VHS can cause hemorrhaging of fish tissue, including internal organs, and can cause the death of infected fish. Once a fish is infected with VHS, there is no known cure. Not all infected fish develop the disease, but they can carry and spread the disease to other fish.
How it Spreads
VHS can be spread from one waterbody to the next through a variety of means, not all of which are known at this time. One known method of spreading VHS is moving fish from one waterbody to another. This can be done by importation, stocking, or the use of bait fish. Other potential sources of VHS spreading are natural fish movements, recreational boating/angling, bird assistance, ballast water discharge, and sampling activities.
Clinical Signs of VHS
The clinical signs of VHS may include:
- tissue hemorrhaging (bleeding);
- unusual behavior;
- bulging eyes;
- bloated abdomens;
- rapid onset of death
However, these symptoms could apply to many different fish diseases. There is no clear visual diagnostic to confirm VHS. Additionally, not all fish infected show any signs and may become carriers of the disease. The only way to confirm VHS is to test the fish in a lab.
What Happens to the Fish Population in a Body of Water Once VHS is Present
The impact of the Type IVb strain of the VHS virus on fish populations is uncertain. It has caused fish mortalities ranging from a few fish to thousands.
History of VHS
- First Discovered - VHS was first discovered in the mid 20th Century in Europe. It was originally a significant and costly disease of cultured rainbow trout. Since its initial discovery in Europe, four strains of the VHS virus have been identified, including both freshwater and marine strains.
- 1988 - VHS was reported in spawning salmon in the Pacific Northwest. It was determined to be a new strain of the virus (Type IV) that appears to be a North American strain. It is widespread in the Pacific herring and Pacific cod populations in the Pacific Northwest. It has also been found in Atlantic herring and Greenland halibut in the Atlantic Ocean.
- 2005 - A very large die-off of freshwater drum in Lake Ontario and a muskellunge kill in Lake St. Clair were linked to VHS. This represented the first documentation of the disease in freshwater in the western hemisphere. A subsequent test of an archived muskellunge collected from Lake St. Clair in 2003 tested positive for the virus. This indicates that the virus was present, but undetected in the Great Lakes system for at least two years. The drum and muskellunge virus isolates were determined to be different than those from infected fish from other regions. They were categorized as a unique strain of the virus (Type IVb).
- 2006 - Additional fish kills in Lake Huron, Lake Erie, Lake Ontario, the St. Lawrence River and Conesus Lake were linked to VHS. Species involved in fish kills linked to VHS included muskellunge, smallmouth bass, northern pike, freshwater drum, lake whitefish, gizzard shad, yellow perch, black crappie, bluegill, rock bass, white bass, redhorse sucker, round goby, burbot and walleye. Other freshwater fish species that have tested positive for VHS are chinook salmon, bluntnose minnows and emerald shiners.
- 2007 - VHS continued to spread throughout the Great Lakes region. Lake Michigan became the fourth Great Lake with VHS-positive fish. Fish kills from inland waters in New York (Skaneateles Lake, Seneca-Cayuga Canal, and private pond in Ransomville), Wisconsin (Lake Butte des Mortes, Lake Winnebago), and Michigan (Budd Lake) were also found to be linked to VHS. In addition, the virus was detected in several new fish species including lake trout, rainbow trout, and common carp.
- 2008 - VHS was found in muskellunge from Clearfork Reservoir in Ohio (Ohio River drainage).
- 2009 - VHS was found in bullheads from Baseline Lake in Michigan (Great Lakes drainage) and in ciscoe from the Apostle Islands, WI area of Lake Superior.
- 2017 - VHS was linked to fish kills in Cayuga Lake (New York), Lake St. Clair (Michigan) and western Lake Erie.
VHS has been blamed for fish kills in:
- Lake Michigan , Lake Huron, Lake St. Clair (MI), Lake Erie, Lake Ontario, St. Lawrence River, Skaneateles Lake, Seneca-Cayuga Canal, Conesus Lake, Cayuga Lake, a private pond in Ronsomville, and several inland lakes in Wisconsin and Michigan.
VHS has been found in the following waters in New York:
Lake Ontario, St. Lawrence River, Lake Erie, Niagara River, Cayuga Lake, Conesus Lake, Skaneateles Lake, Seneca-Cayuga Canal, a private pond in Ransomville
The World Organization of Animal Health has categorized VHS as a transmissible disease with the potential for profound socio-economic consequences. Because of this, they list VHS as a disease that should be reported to the international community as an exceptional epidemiological (study of diseases in large populations) occurrence.
Steps the DEC is Taking in Response to VHS
The DEC filed fish health regulations in 2007 in response to VHS. These regulations were filed to halt the spread of VHS and other fish diseased into un-infected waters in New York.
Additionally, the DEC, in cooperation with the College of Veterinary Medicine at Cornell University, is sampling fish from a number of waters across the state. The sampling includes all waters used as sources of brood stock for DEC hatchery activities. This will help determine how far the disease has spread in New York. The DEC is also working with the USFWS fish pathology lab in Lamar, PA and USDA APHIS (Animal and Plant Health Inspection Service) to conduct surveillance for the presence of VHS in wild fish.
How Anglers and Boaters Can Help Prevent the Spread of VHS
To reduce the likelihood of spreading VHS in New York State, DEC encourages anglers and boaters to abide by the following guidelines:
- Do not transport fish from one body of water to another! Note that this practice is illegal without a DEC fish stocking permit.
- Only release bait fish into the waterbody it was taken from. Bait purchased commercially should not be released into any body of water.
- Do not dispose of fish carcasses or by-products in any body of water.
- Remove all mud, aquatic plants and animals from all gear, boats, motors and trailers before leaving a body of water.
- Drain your live well, bilge and bait tanks before leaving the water. Anglers or boaters using any waterbody known to be infected with the VHS virus should disinfect their live wells and bait wells with a 10 percent chlorine/water solution. Rinse well to remove all residual chlorine.
What to Do if You Find Sick/Dead Fish
If you witness a large number of dead or dying fish (usually 100 or more), please contact the nearest DEC Regional Fisheries Office.
Questions about VHS and potential DEC actions to prevent its spread can be e-mailed to [email protected] or by calling 518-402-8896.