Aquatic Invertebrates of Montana
The Madison River between Quake and Ennis Lakes became infected with Whirling disease about 1990. It has already lost most of its rainbow trout, but brown trout populations have held pretty steady. The parasite has not been found above Hebgen Reservoir and it seems to be moving only slowly below Ennis Lake. Tubifex abundance and life history may explain both of these limits. See E. Richard Vincent's AFS essay on Whirling Disease and Wild Trout: The Montana Experience for some additional background. The Montana Department of Fish, Wildlife and Parks has proposed a major westslope cutthroat trout recovery effort in the upper Madison River
Madison River Drainage Maps
On both of these maps you can click on the sample locations to get more detailed information about the sample or samples from that location.
- Tubifex Sites and Status Map
- Whirling Disease Sites and Status Map from the MTFWP Whirling Disease page.
The Madison River Tubifex Summary
As of January 26, 1997, I have 67 samples from 42 sites within the Madison River drainage, and I have prepared 709 slides and closely examined 4918 worms. This makes the drainage one of the best known in Montana.
The Madison River Mainstem
Through January 26, 1997, I have 35 samples from the Madison River mainstem and I have prepared 432 slides and closely examined 2959 worms from these samples.
Tubifex in the Madison River starts with Hebgen Dam and the heavily abused West Fork Madison River, and it continues downstream all the way to Three Forks. The combination of flow regulation on the mainstem and sediment and manure loading from the West Fork, appear to act synergisticly to impact the river far further than either disturbance could by itself. Those tributaries making it to the river through irrigated fields and heavily grazed pastures add to the problem.
Tubifex is depressed below Quake Lake and again below Ennis Lake as seems to be common in rivers below natural lakes in Montana. From Beartrap Canyon to the mouth, Tubifex becomes increasing seasonal in its occurrence, being depressed during the summer season. This also appears to be normal in Montana's warm trout rivers. These results are summarized in more detail by the following river sections.
- The Madison River above Hebgen Reservoir
- Hebgen Reservoir to Quake Lake
- Quake Lake to Lyons Bridge
- Lyons Bridge to Ennis Lake
- Madison Dam area
- Beartrap Canyon to Three Forks
Madison River Tributaries
Based on current samples and observations from the drainage and elsewhere, Tubifex is unexpected in the Madison River tributaries above Quake Lake. Some exceptions might exist. Tubifex becomes more common the the tributaries entering at lower elevations. Below McAtee Bridge most of the tributaries have Tubifex, at least where they cross the river valley's pastures and fields. As a general rule, only those tributaries upstream of significant irrigation and grazing impacts will lack Tubifex. These results are summarized in more detail by the following river sections.
- Tributaries above Quake Lake
- Quake Lake to McAtee Bridge
- McAtee Bridge to Madison Dam
- Madison Dam to Three Forks
Whirling Disease Risk Assessment
Based on the worms, much of the Madison River drainage is at high risk for Whirling Disease. I guess it is too late to say that! The Madison River drainage above Hebgen Reservoir should be largely safe from whirling disease. The Madison River between Hebgen Dam and Quake Lake should be at extreme risk and it is curious that the parasite is not already there. There should be areas of reduced disease intensity below Quake and Ennis Lakes. Somewhere below Ennis Lake, the incresing Tubifex seasonality should limit the disease severity. This will vary from year to year. High and prolonged runoff should favor Tubifex and the parasite in the Madison River. With the current large snowpact, 1997 could be a year for the disease to intensify below Beartrap Canyon.
Below Quake Lake the risk in the tributaries increases moving downriver. Some of the Tubifex-free tributaries between Quake Lake and McAtee Bridge may be nearly readly to convert to Tubifex-positive streams. Increased disturbance will promote this conversion, increased protection should reverse it. Below McAtee Bridge all tributaries have high risk, at least in the valley area. Tributaries with Tubifex, but without reported whirling disease include Moose Creek, Bear Creek and South Meadow Creek. I would be surprized if less than 2 of these 3 are alreadly infected.
Tubifex Research Needs and Opportunities
The upper Madison River makes an attractive one for research and management experiments for several reasons.
- The disease may be closer to equilibrium here than in many other Montana streams.
- The disease impact seems to show some year-to-year variation here.
- There are substantial variation in Tubifex, temperature and many other environmental parameters within the area.
- There may be more management options possible here than in many areas.
- It is, or at least was, a very important fishery with worldwide appeal.
Tubifex Inventory Needs
- Better establish the limits of the Tubifex depression below Quake and Ennis Lakes.
- Cover the remaining tributaries that are being considered for cutthroat and rainbow restoration and resample the most important and the more Tubifex-prone of these streams.
- More coverage of the tributaries above Hebgen Reservoir. This is currently very sparse.
- Move coverage of the Tubifex-free mountain sections of streams that have Tubifex in the lower sections. This is needed for better balance of total data set.
Tubifex Research Needs
- Establish in better detail the factors affecting the extreme variation in Tubifex abundance and seasonality along the Madison River mainstem from above Hebgen Reservoir to Three Forks.
- Calibrate Tubifex density with disease severity. The areas below Quake Lake and Ennis Lakes should be good for this.
- Calibrate Tubifex seasonality with disease severity. Somewhere below Beartrap Canyon should be good for this.
- Determine the minimal impact methods to prevent grazing from converting Tubifex-free streams into manure-filled, Tubifex-loaded mudholes. Grazing experiments in the West Fork drainage should be possible.
- Determine the minimal impact ways to modify structures and/or operations at Hebgen Dam to minimize Tubifex. Releases from Hebgen Dam could be used to conduct experiments outside the limits nature provides.
Some Management Options
- Modify grazing practices in the West Fork and other key tributary streams to discourage Tubifex.
- Encourage increased use of the Tubifex-free tributaries for spawning and rearing. This is already proposed by the Montana department of Fish, Wildlife and Parks.
- Modify Hebgen Dam or its operation to discourage Tubifex. Removing the dam should be a safe way to discourage Tubifex, but it is likely that more subtile modifications might have important impacts, once the necessary research is done.
- Modify Quake Lake to discourage Tubifex. At the current time there is no way to know what to do, but a few feet higher or lower, might make a big difference.
5 JAN 1997, updated on 29 Jan 1997 D.L. Gustafson
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