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Missouri River trout population decline not as steep as feared By Michael Babcock, Great Falls Tribune, Outdoor Editor Originally published 3 December 2006 Fisheries crews found fewer rainbow trout in Montana’s Missouri River below Holter Dam this fall, but the number of rainbows there remains near the long-term average recorded before whirling disease, drought and a tremendous spike in fish numbers in the late 1990s. They also found that the population of lunkers — trout 17 inches and longer — remains high, while recruitment of young fish — those spending their second year in the river — increased. The decline in 10-inch and larger rainbows, slight as it is, continues the downward trend from 1999 when fish counts in the blue-ribbon section of the Missouri were at an all-time high. Ever since that record year, anglers and fish managers have worried that whirling disease and lingering drought might cause trout populations to collapse. “The Missouri is doing better than we thought,” said Steve Leathe, head of fisheries for Montana Fish, Wildlife & Parks in Region 4. “We expected whirling disease to have a more dramatic impact.” Leathe said there is a definite decline in production of rainbows but that successive years of drought have affected the river and the true impact of whirling disease cannot be known until the drought eases. “It didn’t crash as deeply as we thought. There is resilience in the system,” Leathe said. “Maybe it is in the life history of these trout and maybe more young are avoiding whirling disease better than we thought.”
Outfitter Craig Madsen found the latest fish-count numbers encouraging. “They are still good and certainly encouraging from a recruitment standpoint,” he said. Madsen, owner of Montana River Outfitters, said that his business of guiding anglers on the Missouri was off a little last summer and he attributes that to changes in the fishing. People compare things to their memory of the golden years. Six or seven or eight years ago, the numbers were so great that expectation factor enters into it,” Madsen said. “The fishing is more challenging than it was,” he added. “And it depends on the time of year. The fishing is getting good earlier than it has in the past. People are keying in a little earlier when fish have seen fewer people and there are new hatches coming off.” Madsen also speculated that the fish are getting wiser. “The fish are seeing more anglers and more skilled anglers. Maybe the fish are getting more experienced. Some people will say there aren’t any fish but they do the studies and there are plenty of fish. Have the fish changed their habits? Have they moved? You may have to change tactics and locations,” he said. Survey says From late September to mid-October, fisheries crews surveyed in two sections of the Missouri River: from the Wolf Creek Bridge to Craig, about six miles; and a four-mile stretch around Pelican Point. Travis Horton, the fisheries biologist in charge of the survey, said his crews handled about 3,000 fish this year. “They seemed to be in good shape — there was nothing out of the ordinary,” Horton said. “We handled a few over four pounds, a couple were four-and-a-half pounds and pushing 23 inches. There were quite a few over 20 inches.” The Craig section In the Craig section this year, crews found 2,500 rainbow trout per mile that were longer than 10 inches. In 2005, they found 2,900 fish per mile. Leathe said that the decline of 400 fish per mile is not much. “In the pre-whirling disease average from 1982 to 1998, there were 2,600 fish 10 inches and longer in that same section of river,” Leathe said. “Fresh in everybody’s mind are the great rainbow populations of the late 1990s and the early 2000s. In 1999 we saw the all-time high of 5,100 per mile in rainbows 10 inches and longer. We are now about half of the all time but still right at the pre-whirling disease average.” The number of big fish is down slightly from 2005 but there still are about 1,500 of those lunkers per mile. The average during the pre-whirling disease period of 1982-99 was only 500 per mile. “There are just more bigger rainbows than there used to be,” Leathe said. Why? Leathe says angling regulations are more restrictive and there is a catch-and-release mindset that permeates the angling community that uses that stretch of the river. “There is a lot of peer pressure,” he said. Also in the Craig section, recruitment or production of young rainbow trout appears to be up. The number of yearlings — those mostly 7- to 10-inch trout just finishing their second summer in the river — was up to 1,000 per mile. The last couple of years there were 600 to 700 per mile. Pelican Point In the vicinity of Pelican Point, which is several miles upstream from Cascade, crews found more 10-inch and longer fish than last year: 1,800 per mile, compared to a long-term average of 1,500 per mile. Last year they counted 1,400 trout per mile, a difference that falls into the statistical margin for error in the sampling. “The yearlings looked better than we thought,” Leathe said. This year, they found 850 yearling fish per mile compared with 890 per mile in 2005. The pre-whirling disease average was 1,100 per mile. Leathe says that ups and downs are natural in fish cycles. “In the period of 1993 to 1998, we had consistently above average production. That is what caused the population boom of big rainbows. We had good water years, good flows in spawning tributaries,” Leathe said. Whirling disease, drought Researchers first found whirling disease in North America in 1956. In the disease, a microscopic parasite destroys the cartilage in the heads and spines of young trout and salmon before the cartilage hardens into bone. It cripples infected young fish, which end up swimming in circles. Whirling disease was first discovered in Little Prickly Pear Creek in 1996. Infections in that creek became severe by 1998 and have remained high ever since. In Wolf Creek, a small tributary to Little Prickly Pear Creek, whirling disease infection levels became severe by 2001, according to FWP. Then, the Dearborn River became infected in 2002. Infection levels became severe in the North, Middle and South forks of the Dearborn River in 2003 and in the mainstem river by 2004. Since the Dearborn is a major spawning contributor to the Pelican Point section of the Missouri River, Leathe said biologists expected to see major declines in the young fish there. “We have seen some decline, but only 20 percent below normal,” he said. “That’s not bad. We thought it would be worse.” FWP continues to test Sheep Creek, the Dearborn and the Middle and South Forks, the main stem of the Missouri and Little Prickly Pear Creek. “Nothing has changed very much. Lyons Creek and Sheep Creek just above Pelican Point remain whirling disease free,” Leathe said. Drought also has a major impact on fish, and much of Montana has been severely dry for seven or more years. That affects the Missouri River, because the Bureau of Reclamation has to control flows to satisfy a variety of water users all the way from far southwestern Montana down river. The agency faces a delicate balancing act between filling reservoirs such as Clark Canyon south of Dillon and Canyon Ferry near Helena, and maintaining flows in the Missouri below Holter. As flow drops below 4,100 cfs, the side channels begin to disappear. That forces small fish into the main channel, where they compete with big fish for food and are more vulnerable to anglers and predators. When flows drop below 3,000 cfs, major riffles disappear. The riffles are crucial areas for producing trout food — insects. “(Riffles) also are important spawning and rearing areas for young trout. You really begin to lose habitat and food production,” Leathe said. Fishermen and biologists all hoped for a big flush of the river this year but that never came. Such an event would be a sustained flow of high water for three or four days — enough water to scour clean the riverbed. “The aquatic insect community in the river has changed because there has been no flush,” Leathe said. “Below Holter we are finding more shrimp or anthropods and a lot more aquatic sow bugs and fewer mayflies and caddis flies.” But Madsen still loves the Missouri. “If you look at the overall health of river and the resilience of the river, it has taken some powerful hits and held up well,” he said. “That speaks more to the high quality of the river. Even in these drought years, there are good numbers of fish, but they are a bit more challenging. “Maybe it will cycle back to good old days,” he said. “I think overall it is pretty darned good.” Reflections on the Whirling Disease Initiative (2004-2007) top By Liz Galli-Noble, Program Director
As my three-year experience as the Whirling Disease Initiative (WDI) Program Director, comes to an end on January 31, 2007, it’s a good time for reflection. For those of you who have worked with me, it will come as no surprise that my reflections are overwhelmingly positive.
The spread of exotic pathogens and aquatic nuisance species (ANS) and their impacts on our nation’s natural systems is increasing at an alarming rate. Managing for these invaders and their unpredictable impacts has been confounding and costly for many landowners, states and management agencies. In the early 1990s, one particular invasion—the Eurasian-native, microscopic parasite Myxobolus cerebralis, which causes whirling disease in salmonid fishes—was thrust into the spotlight and generated great concern among anglers, scientists, and fisheries managers. As a result, the WDI was born and, as far as most “fish health” and ANS research and management efforts are concerned, has taken a somewhat unique and enviable path these past 10 years. From its inception, the WDI has benefited from unwavering and sufficient research funding, an effective program structure, and strong leadership—all keys to the success of an applied research endeavor. The WDI’s program model was founded in support of innovative research to understand the disease and perhaps more importantly, to provide tools for management of whirling disease. Scientific leadership and program direction have been provided by a stalwart and engaged national oversight board and a technically-focused and committed technical advisory committee. In addition, the US Fish and Wildlife Service (WDI agency partner) has provided steadfast program support, as has a competent Montana Water Center/Montana State University program administration team. This model, or a modified version of it, could be applied to other fish health and ANS problems. I would encourage other program managers and researchers struggling with related issues to visit our Web site (http://whirlingdisease.montana.edu/) and take a look. I inherited a solid program base in 2004, and made it my goal as director to strengthen other facets of the WDI program. In a united effort, my program partners and I have worked hard to: bolster program accountability; foster better communication amongst project partners, research teams and the concerned public; establish a much-needed outreach program; improve project deliverables; establish a data use policy and an archive to house the volumes of data generated through the WDI; and broaden our research scope to include landscape-scale, synthetic investigations. I am happy to say that all of these efforts have been quite successful. The bulk of the credit for these positive achievements lies squarely on the shoulders of the WDI Steering Committee, members of the National Partnership for the Management of Native and Coldwater Fisheries, Kajsa Stromberg (WDI Outreach Program Coordinator/Program Biologist), Tom Bell and Robert Bakal (USFWS), Kelly Lotts (Big Sky Institute/NBII) and, of course, scores of highly-committed researchers. In times where we are encouraged to work collaboratively, pool our resources, and communicate effectively and in a timely fashion, the WDI provides a good model of how that can be achieved. It has been my pleasure to be a part of that success. Experts convene in China for a closer look at worms top
Black Tale: The Whirling Disease Invaders ~ New documentary film available! top The latest whirling disease science is featured in a new documentary film produced by the Whirling Disease Initiative and the Montana State University MFA Program in Natural History Filmmaking. Filmmakers Stefanie Misztal and Kristin Glover have created an excellent educational film that describes the whirling disease parasite, its life cycle and impacts, and illustrates research and management efforts. Designed for use in hatchery visitor centers or community seminars, the film features beautiful footage of mountain environments, researchers in the field, wildlife, and a computer animation of the parasite’s life cycle. Tips are also included for landowners and anglers to prevent the spread of whirling disease and aquatic nuisance species. The film is available on DVD that includes two versions, one at 26 minutes and one at 14 minutes in length. If you’re interested in obtaining a copy of this film, email whirlingdisease@montana.edu. 2006 Whirling Disease Foundation Update top By David Kumlien, Whirling Disease Foundation Executive Director
The Foundation continued coordination of the whirling disease resistant rainbow trout research project that began in 2000. What started as an anecdote regarding whirling disease resistance in a 150-year-old German strain of rainbow trout has developed into an important whirling disease management tool. As whirling disease resistant rainbow trout research has progressed, the scope of the project has expanded and new research partners have joined the effort. In 2006, whirling disease resistant rainbow trout research was being conducted by scientists from University of California-Davis, University of Munich, Utah State University, Utah Division of Wildlife Resources, Montana State University, Montana Department of Fish, Wildlife and Parks, and Colorado Division of Wildlife. Ultimately, the use of whirling disease resistant rainbow trout will depend on the needs and management strategy of each state and agency. The Whirling Disease Foundation does not become involved in trout management policy, but has, from the beginning of the project, supported sound scientific research that aids responsible decision making. In September, I was very fortunate to be invited by the Colorado Division of Wildlife to participate in the annual trout population estimate on the Gunnison River. It was a fascinating and entertaining trip, and the scenery is spectacular. I saw first-hand the devastating effects of whirling disease on the Gunnison River rainbow trout population. . The Gunnison, once famous for an abundant population of beautiful rainbow, is now nearly devoid of wild rainbow trout. While performing trout fry estimates, we found almost no young-of-the-year rainbow trout, and during adult surveys, we captured only a few adult rainbows. However, I did observe several of the whirling disease resistant Hofer/Colorado River rainbow trout crosses that the CDOW has stocked into the Gunnison during the past two years. It is hoped that the three year old Hofer/ Colorado River rainbow trout crosses will spawn successfully in 2007 and hold the key for re-establishing the Gunnison’s famous wild rainbow fishery. Thanks to Mark Jones, Barry Nehring, Dan Kowalski, and all of the CDOW crew for their hospitality and for their tireless efforts to restore the Gunnison’s wild rainbow trout fishery.
The Whirling Disease Foundation is also pleased to fund a new study investigating the population impacts of whirling disease upon mountain whitefish. There has been limited research regarding the impacts of whirling disease on wild mountain whitefish populations. Since the mountain whitefish is an important component of coldwater stream ecologies, the Foundation recently funded a research project by the Montana Department of Fish, Wildlife and Parks regarding the impact of whirling disease on mountain whitefish. It is hoped that the results of this study will provide an important missing piece of the whirling disease puzzle.
In addition to the previously mentioned research, the Foundation continues to support Tubifex worm research being conducted by Barry Nehring and Kevin Thompson of the Colorado Division of Wildlife on the Windy Gap Reservoir on the Upper Colorado River. Previous research indicates that the number of M. cerebralis triactinomyxons (TAMs) released from Windy Gap Reservoir has dropped dramatically over the past few years, and it appears that this may be the result of a shift in the relative proportion of T. tubifex lineages in the reservoir. It’s possible that there are now more T. tubifex of parasite resistant lineages that produce fewer TAMs when compared to susceptible lineages. Since fewer TAMs generally indicates lower whirling disease risk among fish, developments in Windy Gap Reservoir regarding T. tubifex may provide a useful tool for using resistant , non-TAM-producing worms in ponds and small streams.
Being the lead organizer and host of the annual Whirling Disease Symposium has been an important function of the Whirling Disease Foundation since the first Symposium was held in 1997. The 13th Annual Whirling Disease Symposium will be held in Denver, Colorado on February 12th and 13th at the Grand Hyatt Regency. The meeting is shaping up to be another excellent conference with nearly 40 papers and posters scheduled for presentation. More information on the Whirling Disease Symposium may be found on the Foundation’s Web site at http://www.whirling-disease.org. Whirling disease parasite found in Electric Lake, Utah top By Brett Prettyman, The Salt Lake Tribune Originally published 13 December 2006  Anglers are attracted to the Wasatch Plateau in central Utah because there are so many waters. If fishing is slow at one spot they hit the road for a few minutes and try another. That’s great for anglers, but state wildlife officials fear that accessibility will help whirling disease spread rapidly across fisheries on the Manti-La Sal National Forest.Utah Division of Wildlife Resources (DWR) officials announced Wednesday that the trout malady that deforms and sometimes kills young trout was confirmed in Electric Lake. The whirling disease parasite was discovered in May in Huntington Creek, which flows from the dam at Electric Lake, and fisheries biologists had hoped the cement barrier would help prevent the spread of whirling to the reservoir. “We’ve had biologists watch people fishing in Huntington Creek and then head to one of the reservoirs and walk right in with the same waders they used in the creek,” said Paul Birdsey, regional aquatics director for the DWR. “If you want to move whirling disease around that’s the way to do it.” Electric Lake was once used as a brood stock natural fishery for Yellowstone cutthroat trout. The state has since changed its cutthroat focus to native strains like Colorado River and Bonneville cutthroat, but Electric Lake is still largely supported by natural reproduction. Hybrid tiger trout have also been recently introduced. Electric Lake is also a popular place for anglers to trap red-sided shiners to use for bait and Birdsey is worried mud from those traps and other gear used at Electric Lake will lead to other fisheries being exposed to whirling disease. “Anglers need to be that much more careful,” he said. There is no evidence of human health issues in eating trout infected with whirling disease. Wildlife officials have scheduled nearby reservoirs - Huntington (also known as Mammoth), Cleveland, Boulder and Benches - to be tested for whirling disease. The results will likely be released at this time next year. Association of Pacific Coast Geographers awards whirling disease student paper top Kiza Gates, Katharine Meehan and Christopher Guy (serving as advising professor) recently received an award for Best Student Paper by the Association of Pacific Coast Geographers for their paper, “Angler movement patterns and the spread of whirling disease in the Greater Yellowstone Ecosystem.” Their research investigated the role of anglers in the dissemination of whirling disease among river drainages, and analyzed the phenomenon in context with other invasive species. Partially funded by the Whirling Disease Initiative, the paper can be viewed on the APCG Web site (http://www.wou.edu/~khes/pacifica/pacificafa06.pdf).
All WDI Reports now available online! top All of the Whirling Disease Initiative Final Research Reports for funding cycles 1997 to 2004 are now available online through the Initiative’s Bibliography at http://whirlingdisease.montana.edu/biblio/default.htm. The reports are searchable by authors’ names, keyword and year. More recent reports (2004 - 2006) are not yet available because WDI researchers have the option to keep their reports confidential for a two-year period in order to publish their results in scientific peer-reviewed publications. As these reports are made available for public viewing, they will be added to the online database. We hope this is a useful resource for you. Meetings and Conferences top 13th Annual Whirling Disease Symposium; February 12-13, 2007; Denver, Colorado Montana Chapter American Fisheries Society; February 13, 2007; Missoula, Montana Idaho Chapter American Fisheries Society; February 21-23, 2007; Boise, Idaho Western Fish Disease Workshop; June 4-6, 2007; Jackson Lake Lodge, Wyoming For more updates and events, visit: http://whirlingdisease.montana.edu/resources/events.asp |
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