Help Prevent Unwanted Invaders
Last Update/Review: August 6, 2002
Aquatic organisms have been accidentally or deliberately moved from water body to water body. This practice is illegal and dangerous. Undesirable species, parasites and diseases can upset the delicate balance of ecosystems and sport fisheries, as well as cause millions of dollars in damage.
Anglers, and boaters in general, can help prevent the movement of such organisms by carefully washing their waders, fishing equipment, water containers, boats and trailers (float planes) clean of all mud, plants and river or lake water. Never transport fish, aquatic organisms, plants or water from one area to another.
Remember, many plants and animals can survive out of water for several weeks in moist conditions, so please clean carefully. Anglers visiting other provinces, territories or the United States should always clean their equipment before leaving and before returning.
Whirling Disease
Whirling disease in trout has not been found in Alberta. However, it has been found in the western United States, including Montana. Whirling disease is a European fish disease that was discovered in the United States during the 1950s and spread to the western states between the 1960s and 1990s.
Whirling disease is an infectious disease that affects trout, especially rainbow trout. It is caused by a microscopic parasite that attacks cartilage in the skull, gill arches and spinal column. Infected fish usually swim in a distinctive whirling or circular fashion and can have skeletal deformities and black tails. The disease affects young trout especially and can be fatal to heavily infected fish.
Whirling disease is commonly spread through an intermediate host, the tubifex worm, which lives in the mud of stream and lake bottoms. The worm releases a form of the parasite into the water. The parasite attaches itself to the skin of fish and invades the body. The whirling disease parasite can be spread by transporting infected mud and water on fishing gear, boats and trailers, by the release of parasite spores from decomposing infected fish. Birds and mammals cannot become infected, and infected fish are completely safe for human consumption.
As a precaution, only trout from disease-free hatcheries can be imported to Alberta, which reduces the chance of fish disease entering our area. Fish-disease testing at Alberta hatcheries is an ongoing process. Anglers visiting the western United States should carefully wash their waders, fishing equipment, boats and trailers clean of all mud, plants and river or lake water.
Zebra Mussels
Zebra mussels, recognized by their brown-and-white striped shells, have not been found in Alberta. These small clam-like animals were accidentally introduced from Europe into the Great Lakes in the mid-80s and have since spread to a number of inland lakes and streams in Ontario and Minnesota. Zebra mussels live in extensive colonies, multiply rapidly and cause damage to municipal water intakes, boat engine cooling systems and fish habitats.
Anglers visiting Ontario and Minnesota can help prevent the further spread of zebra mussels by cleaning their fishing equipment, boat and trailer or float plane. Zebra mussels can survive out of water for several weeks in moist conditions, so please clean carefully.
