Viral Hemorrhagic Septicemia (VHS)
Introduction | Response to VHS
| NYS Response to VHS
Viral hemorrhagic septicemia (VHS) is a serious disease of fresh and saltwater
fish, both in the wild and those raised for commercial aquaculture. VHS is
caused by an aquatic rhabdovirus. In its most acute form, VHS can cause
hemorrhaging in the eyes, skin, gills, fin bases, skeletal muscle and internal
organs, leading to high mortality rates. Infected fish may become hyperactive
and display such symptoms as swimming in circles or in a corkscrew pattern,
sometimes accompanied by a twisting of their bodies. In its chronic form, the
disease results in similar symptoms except that fluid accumulation in the organs
replaces hemorrhaging and mortality rates are lower. There is no cure. Fish that
survive infection with the VHS virus can carry the virus for the rest of their
lives, often with no symptoms, spreading the disease and infecting additional
fish. Not all infected fish show symptoms but may be carriers of the disease.
VHS does not pose a threat to human health.
The VHS virus is native to eastern and Western Europe (where it has affected
cultured rainbow trout), the Pacific coast from
California to
Alaska (in Pacific herring and cod), and the Atlantic coast of North
America (in Atlantic herring and
Greenland halibut). The actual vector for the virus’s introduction
into the
Great Lakes is unknown. It is suspected that it may have been
transported in ballast water or by migratory fishes from the Atlantic coast. It
is possible that baitfish harvesting and movement, recreational boating and
angling, as well as aquaculture activities are responsible for the spread of the
virus since it arrived in the
Great Lakes. Waterfowl may also play a role.
The virus is believed to have been present in Great Lakes muskellunge in
Lake St. Clair since 2003. In 2005, several hundred tons of
freshwater drum, muskellunge and round gobies died of VHS in
Lake
Ontario. Since that time, VHS-related fish kills of
black crappie, bluegill, burbot, freshwater drum, gizzard shad, lake whitefish,
muskellunge, northern pike, redhorse sucker, rock bass, round goby, smallmouth
bass, white bass, yellow perch, and walleye have been confirmed in Lakes Erie,
Huron, Michigan and Ontario, and the Niagara and St. Lawrence Rivers. Inland
sightings of the virus in
New York include Conesus and
Skaneateles
Lakes, the
Seneca-Cayuga
Canal, and a private pond in Ransomville (Niagara
County).
Almost 50 species of fish are known to be susceptible to VHS, including such
commercially and recreationally important species as brook trout, Chinook
salmon, lake trout, rainbow trout, walleye, smallmouth bass, northern pike,
yellow perch, and muskellunge. The virus has also been found in bluntnose
minnows, Chinook salmon and emerald shiners but has not resulted in die offs of
those species. The ultimate potential impact of VHS on
North American fisheries is still unknown, but there is the potential for
significant fishery, angling, tourism, and economic consequences.
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 vector is moving fish from one
waterbody to another by importation, stocking, or bait fish transport. Other
potential transmittal vectors are natural fish movements, recreational
boating/angling, waterfowl, ballast water discharge, and lake resource sampling
activities.
Anglers and boaters can reduce the likelihood of their spreading VHS from
waterbody to waterbody by adhering to the following guidelines:
Do not transport fish of any type from one body of water to another. [Such
transport is illegal without a DEC fish stocking permit]
Do not dispose of dead fish or fish parts in any body of water
Do not release any baitfish into any waterbody other than the one from which the
bait was harvested. Commercially purchased bait should not be released into any
waterbody
Remove all mud, aquatic plants and animals (such as snails, zebra mussels, etc.)
from all fishing gear, boats, motors and trailers before leaving a waterbody
Drain live wells, bait tanks and bilge areas before leaving any waterbody. If
the waterbody you are leaving is known to be infected with VHS you should
disinfect live wells and bait wells with a 10% chlorine/water solution followed
by a thorough rinse to remove any residual chlorine
In order to prevent or delay the spread of VHS to other states, APHIS (the
Animal and Plant Health Inspection Service) issued a Federal Order on 24 October
2006. The Order prohibits the importation of certain species of live fish from
the Canadian provinces of
Ontario and
Quebec and interstate movement of the same species from
Illinois,
Indiana,
Michigan,
Minnesota,
New York,
Ohio,
Pennsylvania and
Wisconsin. The species included in the federal
prohibition are: black crappie, bluegill, bluntnose minnow, brown bullhead,
brown trout, burbot, channel catfish, chinook salmon, emerald shiner, freshwater
drum, gizzard shad, lake whitefish, largemouth bass, muskellunge, northern pike,
pumpkinseed, rainbow trout, rock bass, round goby, silver redhorse, smallmouth
bass, trout perch, walleye, white bass, white perch, and yellow perch.
Additional information on the Federal Order can be found on the APHIS website at
http://www.aphis.usda.gov/animal_health/animal_dis_spec/aquaculture/downloads/vhs_fed_order_amended.pdf
On 6 June 2007, the NYS Department of Environmental Conservation finalized fish
health regulations to prevent the spread of VHS in the inland waters of the
state. These regulations include such actions as prohibiting the transport of
fish from one body of water to another and restricting the use of baitfish to
the waterbody from which they were harvested unless certified as VHS free. These
regulations can be found at:
http://www.dec.ny.gov/outdoor/33072.html.