July 1, 2006 - Admin
The Not Funny Fishing Disaster with the Funny Name
When one particular species of wildlife is threatened, it affects all of us who enjoy the great outdoors and sports such as hunting, fishing, camping and hiking. Whirling Disease is a particularly devastating disease for certain salmonoid fish (trout, salmon and whitefish).
The disease endangers the most sought after trophy fish and some threatened and endangered species as well, such as; Rainbow, Steelhead, Cutthroat and Brook trout. The prized Sockeye, Danube and Chinook salmon are also highly susceptible to the disease. Whirling disease is a huge threat to the recreational fishing industry, which in turn is an important source of tourism. For example, it’s estimated that trout fishing brings $300,000,000 in recreational expenditures to just the state of Montana alone; and Montana is one of the states hardest hit by the disease.
Fish, wildlife and parks departments of many affected states are faced with extra expense in modifying fish hatcheries and the need for increasing stocking programs. Agencies also suffer the loss of revenue (fishing licenses, park usage fees, etc.) when anglers avoid an area because of infected or low numbers of trophy fish.
This added expense and lowered revenue stretches already tight budgets causing programs for hunting, hiking, camping and other outdoor sporting activities to sometimes be curtailed. Park expansion plans are delayed, affecting campers, hikers and hunters. Budgets for other forms of wildlife preservation plans are sometimes cut or activities are postponed.
Whirling disease, first discovered in the U.S. in 1956, is now found in at least 23 states. However, the organism responsible for the disease, M. cerebralis, is a native of Europe. From the first description of M. cerebralis in Germany in 1893, it was recognized that whirling disease could severely affect the very new, but rapidly growing trout farming activities with the goal of introducing trout as a food crop in Europe.
M. cerebralis has a complicated life cycle involving two hosts. This pathogen is very hardy, it can survive freezing for over 3 months, aging in mud for at least 5 months and passage through the alimentary canal of northern pike and other animals. The M. cerebralis first invades an aquatic worm, T. tubifex, found in stream beds. After infection, the worm releases a parasite called a TAM, into the stream flow. It’s the TAM that attacks young fingerling trout, entering through the skin, mutating and traveling rapidly to the head and spinal cartilage. The parasite multiplies quickly, applying pressure to nerves, causing equilibrium problems and cartilage damage. The lack of equilibrium and skeletal deformities can cause the fish to swim abnormally or to whirl. The disease gets its name from this whirling motion seen in some infected fish.
The history of whirling disease is extraordinarily diverse and covers over 150 years and numerous foreign countries. Even with 150 years of hindsight, fish husbandry officials seemed to miss the signs of a true wildlife disaster in the making. This history has been very nicely chronicled by Bartholomew & Reno (2002) detailing the history, time line and the paths the infection has taken as it progressed from country to country.
One reason the parasite has passed so silently around the world without outcries from governmental, environmental and sport fishing groups is because the disease was thought to be limited to hatcheries. However, since the 1990’s the disease has been confirmed in wild trout species in diverse locations. Many of these parasite-infected streams are the renowned trophy trout waters where anglers have lovingly fished year after year and others are streams where anglers dream to fish at least once before they make their final cast.
Sadly, the parasite has been confirmed in the following rivers: Yellowstone (in both Montana and Wyoming), San Juan (New Mexico), Beaverkill (New York), Au Sable (Michigan), Madison (Montana), both Henry’s Fork and South Fork of the Snake River (Idaho) and Frying Pan (Colorado). This is certainly far from an exhaustive list of the parasite affected rivers and streams. However, I’d be willing to bet all the rivers just mentioned would appear on the quality end of every angler’s list.
As early as 1968, the Federal Government took an active interest in preventing the importation of the pathogen. The Canadian government quickly followed by passing their own version of the U.S. Title 50 requirements, but it took another quarter century before the threat to fish in the wild was taken seriously. Thankfully, in the last decade, whirling disease seems to be getting the recognition and the call to action it deserves.
A broad coalition of interested parties, including the federal government, state and local governments, private companies and organizations are now actively pursuing the eradication of whirling disease. The U.S. Fish and Wildlife Service, Trout Unlimited and the Whirling Disease Foundation are just a few of the organizations actively studying ways to control the damage caused to wild fish populations.
Sports fishermen, hikers, campers and other outdoor enthusiasts can also do their part in preventing the spread of the disease. Important steps to take are:
- Never carry live fish from one body of water to another (This is illegal in many states).
- Salmonoid parts should not be used as cut bait.
- Carefully clean any mud from boat bottoms and drain any water before leaving an infected area. More parks and commercial operations are providing wash areas for this purpose.
- Carefully clean fishing equipment after use. Waders and especially felt soled wading boots can be a haven for the spores and should be disinfected.
- Fish bones or entrails should not be discarded in or near a body of water. Also, do not dispose of fish parts in the kitchen disposal; instead discard in dry waste destined for a landfill.
The future is not all doom and gloom for trout fishing. Some trout, notably brown trout are not particularly susceptible to the disease. There are disease resistant salmon as well. The research initiatives mentioned earlier are also bearing fruit. The sizable resources of modern science are being used to delve into the complicated life cycle of the disease.
A recently released report found that T. tubifex (the host for M. cerebralis) actually have several genetically distinct lineages. It’s hoped that the differences in lineages can be harnessed as a tool to manage the disease. A resistant strain of T. tubifex found in Canada, actually ingested and deactivated M. cerebralis. This could lead to using a strain of resistant T. tubifex to filter the disease organism from sediment before the less resistant worms are infected.
Healthy fish and healthy habitats generally guarantee healthy people. Aquatic animal health impacts all of us who enjoy the outdoors. No matter if your passion is hunting, fishing, camping, hiking or another outdoor activity, the environment and its animals are delicately interwoven.
The Whirling Disease Foundation can be found at www.whirling-disease.org. The Whirling Disease Initiative is at whirlingdisease.montana.edu. This article is based on numerous sources, many of which can be found at these two sites. A bibliography is available on request. I’m responsible for distilling these many sources and any errors are assuredly mine, not the researchers or editors of my source material.
Wesley Slade is the President and CEO of Slade’s Shooting Sports. Slade’s is a well stocked store with the hunter, camper and outdoorsman in mind. Visit this popular on-line store at? WWW.Slades.Biz. For informative articles and industry information, visit the company’s blog located here: blog.