Stop the Spread-Whirling Disease

Trout Unlimited Canada’s Stop the Spread campaign focuses on preventing the spread and impact of invasive species and pathogens that threaten Canada’s fisheries. There are a number of invasive species threatening Canada’s water. Meet Myxobolus cerebralis, better known to most as whirling disease.

Brown Trout infected with Whirling Disease

Whirling disease is caused by a microscopic parasite that lives in the sediment of waterbodies and affects the younger life stages of some salmonid species such as trout, salmon and whitefish. As an infected fish can’t feed efficiently or avoid predators, whirling disease can be fatal. Symptoms can include the following:

1. “Whirling”, circular, swimming pattern

2. Skeletal deformities of the body or head

3. Darkened or black tail.

It is also common for fish to carry the disease without showing any symptoms.

Whirling disease likely originated in Europe where native brown trout developed resistance to the disease. The disease spreads primarily through the transfer of already infected fish, fish parts along with mud and water containing the spores. Hatcheries are also considered as possible sources. Whirling disease requires two hosts, the Tubifex worm (which reside naturally in the sediments of lakes and streams) and a salmonid fish.

Impact of Whirling Disease to the Environment

Currently, cases of whirling disease in Canada have only been identified in Alberta. However, this disease can impact populations of susceptible salmonid species and severely limits water recreational activities (e.g. waterskiing, fishing).

Why Should We Care?

1. Whirling disease kills trout.The disease is particularly hard on juvenile trout. have resulted in severe population losses of trout in some systems, in some cases up to 90%.  

2. There is no known cure or remedy for whirling disease.  

3. Whirling disease can spread quickly throughout river systems.  Becoming familiar with whirling disease and taking steps to stop the spread is critical.

4. The loss of tourism and other economic impacts of whirling disease results in losses into the millions of dollars.

How Can You Stop the Spread?

1. Become familiar with whirling disease and its impact on fisheries

2. Using the Clean, Drain, Dry philosophy, remove any mud, vegetation and other debris from all equipment that entered the waterbody (e.g. boating, wading and fishing equipment) before leaving the waterbody. Use of car washing facilities is not recommended as disposal of the dirty water from the facilities may not be to a wastewater treatment plant that has the required processes in place for removal of the whirling disease spores.

3. Allow time for equipment to thoroughly dry prior to entering another water body.

4. Drain boats, equipment, coolers, live bait wells and any holder of water which can hold the parasite before leaving the site.

5. Never move fish, whether alive or dead or fish parts.

6. After cleaning fish, dispose of all fish waste in a garbage bin on site.

7. Talk and inform others about the dangers of whirling disease and other aquatic invasives.

8. Support Trout Unlimited Canada’s Stop the Spread program.