WHIRLING DISEASE, SALMONIDS - USA (02): (UTAH) TROUT
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Date: Tue 5 Jul 2011
Source: The Salt Lake Tribune [edited]
<http://www.sltrib.com/sltrib/outdoors/52106983-117/fish-disease-whirling-strawberry.html.csp>
Whirling disease hits Currant Creek; Strawberry Reservoir next?
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There hasn't been a lot of news going around Utah, or the country for that matter, about whirling disease in recent years. It seems the disease has been accepted as a part of fishery management.
Utah hasn't been significantly impacted, largely because there is little natural trout reproduction and planted fish are usually at least 8 inches long.
Kokanee salmon at Flaming Gorge were discovered with the whirling disease parasite last fall [2010] and now there is another water.
Chris Wilson, director of the Utah Division of Wildlife Resource's
(DWR) Logan Fisheries Experiment Station, confirmed evidence of the disease has been found in trout in Currant Creek. The fact whirling is in the popular fishery below Currant Creek Reservoir is bad, but how it got there and where it could go may be even worse.
Currant Creek Reservoir is connected via pipeline to Strawberry Reservoir, one of the state's most important trout and salmon fisheries.
"Obviously, there are concerns about the cutthroat trout and kokanee salmon in Strawberry," Wilson said. "We rely heavily on natural reproduction at Strawberry and if the parasite gets in there the fish would be exposed at a young and vulnerable age. At that stage the deformities could be worse and it could be fatal."
This is not the 1st time Strawberry has been threatened by the fish malady. Whirling disease was found in the West Fork of the Duchesne River back in 2007. That wouldn't usually be a concern, but there is a Central Utah Water Project Pipe on the West Fork that hauls water over a ridge to Currant Creek. The West Fork was treated with chemicals to kill the fish above the pipeline and a barrier was put in to prevent fish from getting above the diversion.
Two things have happened since then. Fish tested positive for whirling above the barrier this spring [2011] and infected fish have been discovered in Currant Creek below the reservoir. A 22 Jun 2011 report shows that 37 of the 57 trout (browns and rainbows) collected last fall [2010] turned up with the disease.
"It could be that it has already come down through the diversion and into Currant Creek Reservoir and then gone down to the creek," Wilson said. "Or it could have come from fish swimming up the Duchesne and into Currant Creek."
If it is the latter, the invasion of the parasite to Strawberry could be prevented for a few more years, but if it is already in the reservoir it could also already be in Strawberry. Fish samples collected last fall at Strawberry came back negative for whirling disease, as have all fish tested at the reservoir.
To prepare for the eventual, and pretty much expected, arrival of whirling disease at Strawberry, biologists have been stocking the Hofer-Harrison strain of rainbow trout. The fish has a built-in resistance to whirling disease.
"About half of our annual planting of 500 000 rainbows are Hofer-Harrisons," said Strawberry Project Leader Alan Ward. "We are making an effort to get even more of them planted in coming years."
A larger concern is the cutthroat trout in Strawberry. State biologists have turned to the aggressive Bear Lake strain of the Bonneville cutthroat to help control Utah chub populations in the reservoir. It has been working, and thanks to a protective regulation that allows the cutthroat to grow to a larger size, the chub are under control. Also important is the fact that they are reproducing naturally in the Strawberry system. That's important because if enough fish are produced with natural recruitment, less fish have to be planted from state hatcheries, allowing fish to go to other waters.
[byline: Brett Prettyman]
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ProMED-mail
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[Whirling disease affects fish in the trout and salmon (salmonid) family. By damaging cartilage, whirling disease can kill young fish directly, or cause infected fish to swim in an uncontrolled whirling motion. This can make it impossible for them to escape predators or to effectively seek food.
Whirling disease is caused by a microscopic parasite called _Myxobolus cerebralis_. The parasite was introduced to the United States from Europe in the 1950s and has spread to many streams across the country. The whirling disease parasite has been found in wild fish and fish hatcheries in 25 states.
Once established in a stream, the parasite cannot be eradicated, nor can its worm host, without significantly damaging the ecosystem.
Whirling disease has no known human health effects. Currently there is no known treatment for affected fish. However, practice management in hatcheries can reduce the risk.
The disease does not affect humans, only fish in the trout and salmon family. The infective stage of the parasite can penetrate human skin and tissues but it does not survive at a human's natural body temperature. Therefore the disease is harmless to humans and even if an infected fish is consumed, it will not affect humans.
The disease can be quite devastating to fish and is a concern for all when it is found in a body of water. Anglers can help by disinfecting boats, boots, lines, live-wells, and other equipment prior to arrival at a new/different body of water.
Portions of this comment were extracted from <http://whirlingdisease.montana.edu/>. - Mod.TG
Utah can be located on the HealthMap/ProMED-mail interactive map at <http://healthmap.org/r/10Cq>. Currant Creek and Strawberry reservoirs can be seen on the map of Utah at <http://water1.cuwcd.com/reservoirs/Images/Reservoirs/reservoirMap.gif>.
- Sr.Tech.Ed.MJ]
[see also:
Whirling disease, salmonids - USA: (UT, MD) 20110520.1528
2007
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Whirling disease, fish - USA (AK) 20070606.1826 Whirling disease, fish - USA (MD) (03) 20070505.1454 Whirling Disease, fish - USA (MD) (02) 20070217.0598 Whirling disease, fish - USA (MD) 20070215.0571
2006
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Whirling disease, fish - USA (UT) 20061214.3517 Whirling disease, fish - USA (OR): transmission 20061105.3175
2005
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Whirling disease, fish hatchery - USA (UT) 20050429.1194] .................................................sb/tg/mj/sh/ll
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