Trout Unlimited Canada’s Stop the Spread campaign focuses on preventing the spread and impact of the invasive species and pathogens that threaten Canada’s fisheries. There are a number of invasive species threatening Canada’s water. Meet one of the most serious threats to Canada’s fish, Viral Hemorrhagic Septicemia (VHS).
Identification
Photo by Dr. P. Bowser, Aquatic Animal Health Program, CVM, Cornell University. Photo courtesy of the Center for Food Security and Public Health, Iowa State University.
Viral Hemorrhagic Septicemia is a deadly infectious disease to both freshwater and marine fish. The VHS virus has been found in farmed rainbow trout in Japan and Europe as well as fish in both the Atlantic and Pacific oceans. VHS was first detected in Canada in Lake Ontario in 2005. It has since spread to all the Great Lakes and a number of tributaries.
Clinical signs of freshwater-impacted fish may include one or all of the following symptoms:
Bulging eyes
Pale gills and organs
Bleeding on the body and organs
Dark body coloration
Swollen abdomen
Gasping at the surface
Corkscrew swimming behavior
Death
How Do Fish Contract VHS?
The exact cause of Viral Hemorrhagic Septicemia is not known but it is considered to be a mutated marine virus that became pathogenic for freshwater fish. The latest science suggests that VHS is probably native to certain areas.
How Does VHS Spread?
Due to its primary method of spreading via urine and reproductive fluids, VHS transmission to other fish can occur through direct contact with contaminated water or infected fish. The VHS virus enters a fish through the gills or wounds. VHS can also be spread through contact with nets, buckets, footwear and vehicles, as well as fish-eating birds, such as herons and ‘carrier’ fish. Healthy, uninfected, fish can also contract VHS by consuming infected fish. The effect of VHS virus on fish species is influenced by environmental conditions such as water temperature; the optimal temperature for infection is 9-12 degrees Celsius.
Why Should We Care?
VHS impacts our fisheries and fish. The VHS virus has resulted in large die-offs of freshwater species including Walleye, Freshwater Drum, Bass, Muskellunge, Black Crappie, and Bluegill in the Great Lakes.
Due to its infectious nature, the VHS virus has been found in more than 50 species of freshwater and marine fishes.
VHS can change and mutate. The Great Lakes substrain of VHS virus is suspected to be a newly evolved variant of the native North American Genotype.
How Can You Stop the Spread?
Become familiar with VHS and its impact on fisheries
If you fish with bait, use only locally harvested baitfish and roe. Request from bait dealers the location of their supply sources to ensure they are buying locally.
Do not introduce fish from another country or province into natural waters.
If you see someone moving fish from one water body to another, observe their actions, record what you see and report it to the appropriate authorities.
When cleaning and gutting fish, safely dispose of all fish waste in the garbage.
Using the Clean, Drain, Dry philosophy, remove mud and aquatic plants from gear, boats, anchors, motors and trailers prior transporting them to another water body.
Empty live wells and bilges at least 30 meters away from any water body. Once emptied, disinfect the live well or bilge with a 10% household bleach to water solution
Talk and inform others about the dangers of VHS and other aquatic invasives.
Support Trout Unlimited Canada’s Stop the Spread program.
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