In 2006, significant progress was made in protecting and restoring WCT in the upper Missouri River Drainage, where they are the only native trout. Several ongoing restoration projects and some new projects were part of a cooperative work program between United States Forest Service (USFS) and FWP. Genetically unaltered WCT remain in less than 3% of their historical habitat in the Upper Missouri River drainage. Most populations in northcentral Montana are hybrids (crosses between non-native rainbow trout and native WCT). Also, many populations have vanished because of competition with non-native brook trout. Active restoration efforts are key to preserving this rare legacy of Montana’s past for the enjoyment of future generations.

Since its inception, the cooperative work program has protected genetically pure WCT populations in 23 miles of habitat in 10 streams by suppression/elimination of non-native trout species and construction of 7 fish barriers. In addition, genetically pure native WCT have been transplanted to establish 6 new populations in 8 miles of habitat above natural barrier waterfalls in 6 headwater streams.

In 2006, a barrier to non-native fishes was constructed on the South Fork Judith River after four years of grant-writing, design work, and environmental review. The new fish barrier on the South Fork will protect 25 miles of stream with nearly pure WCT from continued hybridization with rainbow trout. It will also help prevent displacement by non-native brook trout. Stream surveys as early as 2000 indicated hybridization was moving rapidly up the South Fork. Currently, most fish in the lower reaches are either pure rainbow trout or highly hybridized WCT. Over the next several years, non-native fish will be removed using backpack electrofishing equipment. The objective is to have a population of native WCT with genetic purity of 95% or better upstream of the new fish barrier. This project is unique in that it allows for movement of WCT populations between tributaries that join the South Fork above the barrier, while still protecting them from invasion of non-native fishes from down below.

Another project initiated in 2006 was the removal of hybridized WCT from Crawford Creek in the Belt Creek Drainage using rotenone. In 2005, a concrete barrier was constructed on the lower end of Crawford Creek near the Belt Creek Ranger Station. The barrier protects about 1.5 miles of stream habitat from non-native brook trout, rainbow trout and hybridized WCT. In 2007, pure WCT will be transferred from one or two Belt Creek tributaries to the fishless habitat in Crawford Creek. This project adds significantly (4% increase) to the total miles of stream in the Belt Creek drainage that support pure WCT.

Pallid Sturgeon Recovery
A small population of pallid sturgeon (an endangered species) exists in the 240-mile section of the Missouri River from Morony Dam (near Great Falls) to the Musselshell River near Fort Peck Reservoir. A stocking program was initiated in 1998 to preserve the gene pool and begin to repopulate the species in this recovery area. The goal is to build the population to about 1000 adult pallid sturgeon by 2025. This year the pallid sturgeon recovery program was fairly successful and we stocked a total of 4,634 yearling pallid sturgeon in this reach. Since 1998 we have stocked five year-classes, totaling to 47,123 hatchery pallid sturgeon. Survival success of the stocked pallids has been variable with the 1997 year-class having an exceptionally high survival rate of 45% after eight years in the wild. However, the survival assessment for the 2001 year-class indicates that this year-class was a total loss. The survival success of the other three year-classes is unknown at this time, but further monitoring will provide information in upcoming years. The growth rate of these juvenile pallid sturgeon has improved somewhat over last year, with the 9-year-old fish now averaging 25 inches fork-length and weighing 2.0 pounds. Unfortunately, the new 2006 year-class juvenile pallid sturgeon raised at U.S. Fish and Wildlife Technology Center in Bozeman came down with a viral infection and all these 5,000 fingerlings had to be destroyed. Hence it is unlikely that any yearling pallids will be stocked in this area of the river in 2007.

Sauger Status
Sauger have been receiving considerable attention by fisheries crews because of the sharp declines first reported during the late 1980’s. The 2006 survey indicated that sauger numbers are very good from Coal Banks Landing and on downriver. Numbers in the Fort Benton area showed significant improvement and was 120% of the longstanding average here. Sauger numbers in the uppermost area near Morony remain exceptionally low. Since 2002 we have noted that sauger numbers are gradually improving in the mid to upper portions of the middle Missouri River. Sauger spawning success appeared to be excellent both in 2005 and 2006 with several age-0 fingerlings sampled in downstream areas. Some of the juvenile sauger tend to slowly migrate to upriver areas from the lower river. Consequently, strong downstream populations should gradually enhance upper river populations.

Sauger/Walleye Competition Study
A two-year sauger study completed by Montana State University (MSU) student Brian Bellgraph assessed the competition potential between sauger and walleye in a 40-mile reach of the Missouri River between Fort Benton and Virgelle. It was suspected that walleye may be competing with sauger for resources since walleye abundance increased following the drought while sauger abundance remained low or decreased. Seasonal migrations, habitat use, and diets of both species were studied during 2003-05. Thirty-one sauger and 29 walleye were captured and were surgically implanted with radio transmitters in the fall so that their movement patterns and habitat use could be studied. It was found that 96% of saugers and 57% of walleyes migrated downstream as far as 164 miles to spawn. After spawning, both species returned to previously occupied river reaches and many fish returned to the exact areas they inhabited prior to their spawning migrations. Habitat use by sauger and walleye was similar, and both species preferred bluff pool habitat. Diet overlap was high between saugers and walleyes in the springtime, when they both consumed primarily emerald shiners and stonecats. Summer diet overlap was also high with both feeding heavily on stonecats (a small species of native catfish). Diet overlap during the fall was moderate with sauger concentrating on stonecats while walleye consumed a smorgasbord of stonecats, emerald shiners and western silvery minnows.

Sauger and walleye exhibited high overlap for seasonal migrations, habitat use, and diet in the middle Missouri River. This means there is high potential for competition between the two species if food or habitat resources are limiting. However, because both species occur in low numbers in the upper river reach, it is unlikely that walleye are currently excluding sauger recovery in that area.

Ackley Lake
Ackley Lake has been one of the most consistent producers of 1–2 pound trout in central Montana. However, in 2005, mean rainbow trout weight from gill nets was less than 7 ounces and trout were at near record low numbers. It was also the second year that trout were extremely thin. Biologists thought that the high population of suckers might be reducing trout growth. Therefore in 2006, 14,900 pounds (8.2 tons) of suckers were captured in trap nets and dispatched, with carcasses deposited in the reservoir. Circumstantial evidence indicates that sucker removals immediately benefited the rainbow trout. Rainbow trout catch rates in nets returned to near record highs and size and growth improved. Mean weight of fall-netted fish increased to 10 ounces and first year growth of rainbow trout increased from 4.2 inches in 2005 to 6.2 inches in 2006. Five brown trout up to 10 pounds (mean 4 pounds) were also captured during 2006 sampling.

East Fork Reservoir
Yellow perch (mean weight 2 ounces) were captured at record highs (>100 per net) in fall gill nets on East Fork Reservoir, near Lewistown. The reservoir is producing northern pike in the 3-pound range. One northern pike captured during spring trapping weighed nearly 24 pounds. This fish was tagged in 1998 when it weighed about 10 lbs. In December 2006, biologists evaluated the suitability of stocking of several species to diversify the fishery. The assessment recommended stocking largemouth bass, which may be stocked in 2007 or 2008, pending public review and approval.

Big Casino Reservoir
Rainbow trout are not doing well in Big Casino Reservoir. They are smaller and appear to be less numerous than they were prior to the removal of 2.3 tons of suckers in 2001. Only three rainbow trout were captured in the four survey nets set in 2006. These trout were all less than 11 inches long and weighed less than 4 ounces on average. Spring nets captured record high numbers of yellow perch (212 per net) of 2-ounce perch. Perch were illegally introduced a few years ago and have destroyed what was previously a well-balanced fishery for trout and walleye. Despite high stocking rates, record low numbers of walleye (one fish in four nets) were captured. It seems likely that low retention time of water and surface discharge of Big Casino Reservoir flushes most of the stocked walleyes downstream. Due to the recent lack of success, FWP plans to discontinue walleye stocking in 2007. Biologists are currently evaluating options to improve the fishery in this reservoir.

Martinsdale Reservoir
Martinsdale Reservoir was drawn down to less than 10 acres in late summer 2006 for repairs, which resulted in a partial fish kill. A complete winterkill is likely at these low water levels. The repair was not completed and the reservoir is scheduled to be re-filled in 2007. It will be drawn down again starting in August 2007. Biologists plan to stock catchable rainbow trout in May 2007 to provide fishing next summer.

Petrolia Reservoir
Petrolia Reservoir, located south of Winnett, has been providing good walleye and northern pike fishing in recent years with good water levels. The reservoir produces walleye in the 3–10 pound range but most were around ¾ of a pound during fall netting. Northern pike up to about 14 pounds are found in the reservoir. Yellow perch are sparse and several hundred yellow perch (6.5 inch mean length) were moved from Jakes Reservoir to Petrolia in April to enhance spawning stock.

Big Spring Creek
Lewistown’s premier trout stream, Big Spring Creek, continues to provide excellent fishing and trout numbers (>10 inches) in fall 2006 were similar to the long-term average. Numbers of juvenile rainbow trout were below the long-term average in all three sections sampled. Brown trout numbers have been increasing, and they now make up about 50% of the trout population in the creek upstream from Lewistown. Whirling disease infection levels are very high on the lower creek and the infection is slowly spreading to areas of the creek upstream of Lewistown.

Prairie Fish Survey
A survey of 143 sites on 136 streams throughout Region 4 was conducted as part of the comprehensive Montana prairie stream inventory. This was the fourth year of the survey and the first time that most of these streams had ever been sampled. Of the 143 sites sampled, 77 (54%) had water present and 66 (46%) were dry. Fish were found in 73% of the sites that had water. Prairie fish have to be tough, and it doesn’t take a lot of water to keep them going. A total of 17,669 fish consisting of 21 species (12 native and 9 introduced) and seven families were captured. Like the past three years, fathead minnows had the greatest distribution of prairie minnows in Region 4, occurring at 44 sites. Spottail shiners had the highest distribution of non-native species observed and Eastern brook trout were observed in transitional areas between mountain and prairie ecosystems. Most prairie streams surveyed were dominated by native species. Overall, less than 3% of the fish captured were nonnative, most of which were non-native trout. Similar to prior years, the documented range of native species such as brassy minnows, brook stickleback and northern redbelly dace x finescale dace hybrids was extended further westward in Region 4. Northern redbelly dace x finescale dace hybrids, a native species of concern, were identified at 13 sites within 6 major drainages. These observations were important because prior knowledge on the distribution and abundance of this special hybrid species has been limited. Eleven species of reptiles and amphibians were also recorded during the survey. The northern leopard frog was the most frequently observed amphibian, while the western rattlesnake was the most common reptile. The male Northern redbelly dace, brightly colored during the summer months, is one of Montana’s native minnow species found in prairie streams.

Tiber Reservoir
The stage was set in Tiber Reservoir for what biologists hoped would be an excellent production year for cisco during 2006. Back in 1997 and 1998, Fish, Wildlife & Parks introduced cisco (also known as lake herring) into Tiber to supplement the reservoir’s forage base. Since their initial introduction, the only significant natural reproduction occurred in 2002, a year when there was minimal winter drawdown of the reservoir. Maintenance of the reservoir’s water elevation throughout the winter is critical to hatching success, since spawning cisco deposit their eggs in relatively shallow water in shoreline areas during late fall. Deposited eggs incubate all winter under the ice before hatching in early April. Reservoir drawdown during winter 2006 was minimal; Tiber’s water elevation was lowered just 0.4 ft from December through March. Despite what looked like optimal conditions, vertical gill net surveys indicated very limited cisco production occurred in 2006. Biologists will continue to monitor this population and several habitat variables to gain a better understanding of factors that limit or promote production of this forage fish.

Anglers enjoyed another summer of excellent walleye fishing on Tiber during 2006. Weekend creel surveys indicated the average catch rate from May through August was 0.4 walleye per hour for all anglers, with the highest catch rates occurring during June and early July. The average size of harvested walleye declined slightly from 2005, but body condition of these fish improved from previous years. Anglers also reported better-than-average perch fishing, and several trophy-sized northern pike were caught. Growth rates of northern pike have improved dramatically since the introduction of cisco.

Fall gill net surveys indicated walleye numbers remain relatively stable in Tiber. However, there was noticeable improvement in walleye body condition, as was noted in the summer creel survey. A preliminary field check of walleye stomachs indicated they were feeding primarily on young-of-year yellow perch. Following a several year declining trend, abundance of larger yellow perch increased in fall 2006 gill nets, which confirmed what anglers reported during the summer months. Northern pike numbers remain relatively low in Tiber, but their body condition is exceptional. Pike offer a trophy component to the Tiber fishery, attributable to the abundance of cisco in the reservoir. Cisco dominate Tiber’s fish community, accounting for 73% of the total catch in this past fall’s gill net surveys. Unfortunately, adult cisco are still growing too large (about 9.5-inches) for Tiber’s walleye to prey on. However, the reservoir’s northern pike and lake trout are feeding heavily on the abundant cisco.

Lake Frances
Low water conditions again challenged anglers on Lake Frances during 2006. Similar to the past several years, a light snowpack resulted in minimal runoff. During spring and early summer, boat access was limited to the ramp on the east end of the reservoir near the outlet dam, which was often congested. By August, the reservoir had dropped enough that anglers were launching from the recently-constructed low-water ramp located on the island near Valier.

Angler catch rates of walleye were lower in 2006 relative to the previous two years, but average size of harvested walleye increased to about 16.5 inches. Yellow perch numbers rebounded somewhat, as was evident by the numbers reported by anglers in creel surveys. Many anglers reported smaller perch to be a nuisance while walleye fishing. Few northern pike were reported in the creel, but gill net surveys indicated a slight increase in their relative abundance compared to historic data. Fall gill net surveys indicated Lake Frances’ walleye numbers were down significantly from the historic high net catches observed since 2002. Fish between 15- and 20-inches in length now dominate the walleye population. The lower abundance of walleye less than 15 inches in length may indicate reduced recruitment and/or survival of stocked walleye.

Pishkun Reservoir
FWP personnel again trapped and transplanted northern pike from Pishkun Reservoir into nearby Split Rock Lakes during spring 2006. This was the fourth year of these removal efforts, which are directed at reducing predation pressure in Pishkun to improve northern pike growth rates, enhance yellow perch survival, and promote the establishment of a rainbow trout fishery. A total of 1,041 pike were removed during 2006, which resulted in excellent pike fishing opportunities in Split Rock Lakes that many anglers took advantage of.

Despite these removal efforts (over 3,000 pike transplanted the past four years), survival of stocked rainbow trout in Pishkun continues to be poor. Relatively few rainbows are showing up in survey nets, although those that survive exhibit exceptional growth. Three-year old rainbow trout captured in trap nets during spring 2006 weighed four to five pounds, and anglers reported catching rainbows up to 11 pounds. Biologists will examine trap net data to determine if these removal efforts will continue, or if there are other strategies we might try to promote the establishment of a trophy rainbow trout fishery in Pishkun.

Low water conditions continue to plague several fisheries in the Choteau area. Bynum Reservoir, a once popular walleye and yellow perch fishery, has not recovered from several years of drought, despite the area receiving normal precipitation the past two years. Although water from the Teton River was diverted into Bynum Reservoir throughout the 2006 winter, at the start of irrigation season this reservoir contained just 13,500 acre-ft of its 72,000 acre-ft capacity (19%). Thus, after a very brief period of releases, the water elevation in Bynum was again reduced to dead storage by early July. No fish sampling was completed in Bynum during 2006, but biologists hope to assess the status of this fishery during 2007.

Bean Lake
Bean Lake lost another 1.5 ft of water elevation during 2006. Elevation of this natural pothole lake has been declining for several years and it now has a maximum depth of about 10 ft. Because of poor water quality and the declining water elevation, FWP did not stock rainbow trout into Bean Lake in 2006. The reach of Spring Creek that flows through Choteau remained completely dewatered throughout 2006. This small stream once provided excellent angling opportunities for local youths. Low water also continues to plague Eureka Reservoir, an off-stream irrigation storage reservoir in the Teton River drainage. By mid-July, water elevation in this reservoir was too low to launch boats and access was very limited to this popular rainbow trout fishery.

Nilan and Willow Creek Reservoirs
Nilan and Willow Creek reservoirs, located in the Sun River drainage, maintained good water levels throughout 2006 and provided excellent angling opportunities for rainbow trout. Both shore and boat angling are effective in these waters, and stocked rainbow trout commonly reach three pounds and larger in these productive reservoirs. Both reservoirs received an additional stocking of rainbow trout this past fall and should fish very well in 2007.

Sock, Renshaw, Wood, and Tunnel Lakes
Several lakes in the Choteau area are now being stocked with westslope cutthroat trout. Previously, these lakes received either Yellowstone cutthroat trout or rainbow trout. Sock, Renshaw, Wood and Tunnel lakes received plants of westslope cutthroats during 2006 from Washoe Park State Fish Hatchery in Anaconda. This change in management will provide anglers an opportunity to catch this special native fish.

Students and teachers from area schools are participating in the third year of the Sun River Adopt-a-Fish Program. This web-based program allows students to adopt and name a specific fish, and then follow its movements from their classrooms via the internet. This year’s program was kicked off with an October fieldtrip to the Sun River Canyon. Classes from Choteau, Fairfield, Power, and Greenfields schools enjoyed learning about Gibson Dam and the Sun River Irrigation Project, electrofishing, and fish biology. Students also observed their adopted rainbow trout getting implanted with a radio transmitter. Twenty transmitters were implanted into trout in the section of Sun River between Gibson and Diversion dams. Information on the Sun River Adopt-a-Fish Program can be found on the web at: http://fwp.mt.gov/education/adoptafish/sunriver/default.html.

Efforts to establish fluvial (stream dwelling) Arctic grayling in the upper Sun River drainage suffered a setback in 2006. This year was to be the second of a three-year effort to incubate grayling eggs onsite at remote locations in the Bob Marshall Wilderness. Egg incubators were installed in two tributaries of the North Fork Sun River, but hatchery personnel were unable to secure viable eggs from brood fish. Eye-up of fertilized eggs was less than 25%, which was not sufficient to warrant their placement into incubators. Hatchery personnel were not sure why egg eye-up was so poor, but suspected it may have been attributable to the very warm weather that occurred during May. Grayling introduction efforts will continue in spring 2007 with two more years planned for the program.

The Fish, Wildlife & Parks Aquatic Education Program provided classroom aquariums to schools in the communities of Choteau, Bynum, and Dupuyer. These aquariums have proved to be very popular and are an excellent medium for students to learn about Montana’s native fishes. Local school students now know more than just their trout! Brook stickleback, mottled sculpin, brassy minnow, longnose dace, and lake chub are just a few of the lesser-known native species they have become familiar with. The program highlight was when the classrooms received fingerling westslope cutthroat trout from Washoe Park State Fish Hatchery. Now, it is purported that everyone in the community of Bynum knows the story of Oncorhynchus clarki lewisi!

Canyon Ferry Reservoir
It was 10 years ago that an angler in Canyon Ferry Reservoir caught the first documented walleye. Since that point, walleye populations have flourished and the walleye fishery continues to grow in popularity.

Ten years later, biologists are curious about the changes that have taken place in the reservoir; namely, how have anglers responded to the species shift in Canyon Ferry? Rainbow trout and yellow perch established Canyon Ferry as one of the most popular fisheries in Montana for nearly 40 years. How has the shift from a yellow perch/rainbow trout to a walleye/rainbow trout fishery affected angler use and the popularity of the fishery?

Since 1982, FWP has monitored angler use on the majority of waters throughout the state. These estimates provide reliable data and a starting point for biologists to evaluate how fishermen are responding to the species shift in Canyon Ferry. The 2005 angler use estimates for Canyon Ferry was 80,248 days. This compares with the long-term average of 90,296 angler days. The 2005 estimate represents the sixth year of declining angler use on Canyon Ferry, which reached nearly 120,000 angler days in 1999. Other indicators of the shift are seen in the percentage of boat anglers compared to shore anglers. In 1988 when the fishery was dominated by rainbow trout and yellow perch, shore anglers made up 61% of all anglers. By comparison, shore anglers comprised only 17% in 2005 when walleye were the most sought after fish in the reservoir. In 1988, 73% of all anglers were targeting rainbow trout while in 2005, 68% were targeting walleye. Nonresident anglers comprised 8% of the angling pressure in 1988 compared to less than 4% in 2005.

Declining angler use of Canyon Ferry can be attributed primarily to the crash of the immensely popular yellow perch fishery. Anglers targeting perch (predominantly during the winter) comprised approximately 30,000 days annually. Despite continued habitat enhancement by biologists since 1998 and a reduction in the daily perch limit to 15, populations continue to struggle. Perch remain an extremely important food item for walleye; even though perch can produce massive numbers of offspring, very few are living to age 4 (8 inch) because of heavy predation by walleye.

Biologists continue to evaluate hatchery rainbow trout strains (Eagle Lake vs. Arlee) and season of stocking (June vs. October) to determine what combination is the most cost effective. Rainbow fingerlings (fish less than 8”) are no longer being stocked due to heavy predation by walleyes and the goal is to stock only 8-inch rainbow in areas where predation is minimized. Population surveys show good survival of 8” rainbows that were stocked in fall 2005 and spring 2006, so rainbow fishing should improve as biologists learn more about which rainbow strains and seasons of stocking work best.

Hauser Reservoir
Do you want the good news first or the bad news? Lets start with the bad; angler catch rates for rainbow trout have been declining in recent years due to reduced rainbow stocking rates. Stocking rates were significantly reduced while the Lewistown hatchery completed the PCB cleanup project. The good news is that the Lewistown hatchery is back on line and Hauser received the full request of rainbow trout in 2006 (150,000). Historically, fingerling rainbow (5 inch) were stocked and survival was generally excellent. Walleye abundance began to increase in 1998, and stocked rainbow trout fingerlings have survived poorly since then due to heavy walleye predation. Several years of extensive fish marking and monitoring have established that 8-inch rainbow stocked in the late fall provide optimal survival. There is a two-fold benefit to this approach; fish are large enough that walleye predation is minimized, and predator metabolisms are slowing for the winter – meaning they eat less. Amazingly, the 8-inch fall-stocked rainbows will grow through the winter and reach 13-14 inches by the following May, which makes them even less vulnerable to walleye predation when the water warms up in the spring. Rainbow fishing should improve dramatically in 2007.

Walleye relative abundance hit a record high in the 2006 fall sampling nets and angler catch rates were actually higher in Hauser than Holter. Catch rates for small walleye should be good in 2007. First-time walleye anglers have an excellent chance to catch a few “eyes” at the Causeway, which has excellent access for youth and handicapped anglers. Good numbers of walleye ranging from 12 to 18 inches can be found in Hauser as well as a few in the 24 to 28 inch range. Fishing is best during the April-May period and many anglers find success during the evening hours.

Two traps designed to monitor fish movement between Lake Helena and Hauser Reservoir were removed in 2006. The traps were installed under the Causeway Bridge in 2004 as part of the federal relicensing program for Hauser Dam. During the nearly two-years of operation: 99 rainbow and brown trout, 336 kokanee salmon, 24 yellow perch, 167 walleyes, 996 suckers, 32 carp and 2 ling were counted passing under the Causeway Bridge. All of the fish were released alive, and some were tagged. The information collected with these traps assisted biologists in determining sportfish harvest rates.

A study funded by PPL Montana to determine fish loss over and through Hauser Dam started in 2006. For the next several years this study will determine how many and what kind of fish are being lost from Hauser Reservoir. Additionally, it will determine when (time of year) the majority of fish are being lost, and results could be used to test ways to reduce losses, if warranted.

Holter Reservoir
Holter Reservoir rainbow fishing remained strong in 2006 even though the number of hatchery rainbow has been reduced by roughly 80% since the discovery and cleanup of PCB at the Lewistown Hatchery. Catch rates were again good from the boat ramps during April, providing an excellent opportunity for youth and handicapped anglers.

Biologists collected 236,000 eggs from Eagle Lake rainbow trout from Holter in the spring of 2006. These eggs were hatched and reared at the Lewistown hatchery and many come back to Holter as well as other waters in Region 4 (Great Falls Area). In 2006, the Lewistown hatchery was back in full production and Holter received 125,000 Eagle Lake and 125,000 fall release Arlee rainbows. Amazingly, the 7-8 inch Eagle Lake rainbows released in July demonstrated excellent survival and were nearly 12-14 inches by October!

Walleye fishing slowed a bit in 2006 after several years of hot fishing. However, walleye relative abundance increased in 2006 with excellent numbers of small walleye and good numbers of quality and trophy sized fish in the slot and greater than 28 inches. Perch numbers collected in fall gillnets showed a slight increase but are still well below the management plan goal. Keep your fingers crossed that excellent perch production in 2002 leads to an improvement in the winter ice fishing.

Kokanee salmon continue to provide a surprising fishery given the small numbers that have been stocked in Holter in recent years. October produced some relatively good kokanee fishing with numerous fish in the 5-pound range. The majority of kokanee caught in recent years have been hatchery fish stocked in 2002. However, a few wild kokanee have been caught by anglers and in sampling nets indicating that some limited natural reproduction is occurring. Due to extremely poor survival of hatchery kokanee stocked in Hauser and Holter Reservoirs since 1997 (over 3.5 million eggs/fry/fingerlings and advanced fingerlings were stocked), the decision was made to discontinue this program in 2005. However, if surplus kokanee are available from the hatcheries, consideration will be given to stocking them in the Upper Missouri River Reservoirs.

Westslope Cutthroat Trout Restoration Projects
In 1998, a small stream that flows into the Helena Valley was identified as having an extremely rare population of 100% pure westslope cutthroat trout. In 2003 it was discovered that someone had illegally dumped white suckers into a pond on the creek. The sucker population exploded and soon had out competed the cutthroats. In 2004 and 2005 biologists removed 46,000 suckers and estimated the number of cutthroats to be about 200. In the fall of 2005, as many cutthroats as possible were removed and relocated to another pond. The sucker-infested pond was then treated with a chemical to eliminate the remaining suckers. After the chemical had detoxified (about 3 weeks) the cutthroat were brought back to the pond. Sampling in 2006 found ZERO suckers and a bunch of very fat, happy westslope cutthroat trout.

A Long-Term Look at Missouri River Whirling Disease
Our biologists spent a fair amount of time over the past few months trying to get a clearer picture of what the long-term effects of whirling disease have been on trout populations in the Missouri River. The 35-mile section from Holter Dam to Cascade has been the #1 or #2 most heavily fished water in Montana since 2000. The river has become famous for its high quality trout fishery and attracts fly fishermen and women from around the world.

FWP has gathered fish population information by electrofishing the 6-mile section between Wolf Creek Bridge and Craig every year since 1982. This extensive database (25 years and running…) is very valuable for determining long-term fish population trends. Trout populations are notoriously variable and can be heavily influenced by floods, drought, heat, cold, and other factors including water quality and changing patterns of human use. Long-term databases require dedication and commitment to compile, but are very useful for smoothing out the year-to-year variations and giving a clearer view of the “big picture”.

So, what has happened to trout populations in the Missouri River over the past 25 years, particularly with regard to whirling disease? Well, a lot…. and not much. Little Prickly Pear Creek, a major supplier of young rainbows to the river in the Craig area, became heavily infected with the whirling disease parasite beginning in 1997. The parasite is very hard on young rainbows because they have little natural immunity and the parasite consumes cartilage in the young fish, causing deformities and often death. We expected the parasite to take a toll on young rainbows, and expected to see it reflected in numbers of yearling rainbows living in the river in the Craig area beginning in 1998. We compared yearling rainbow numbers in the river from 1982-1997 (pre-whirling disease) to the years 1998-2006 (post-whirling) and found the disease had indeed taken a toll. Post-whirling yearling rainbow numbers averaged only 66% of the pre-whirling years. In other words, this amounted to about a 1/3 reduction in production of young rainbows, which was not as bad as we expected.

One would expect a 33% reduction in production of young rainbows to eventually lead to a similar decline in numbers of adult rainbows, right? However, Mother Nature often surprises, and this is a pleasant one. According to our long-term data, numbers of all rainbows 10” and longer in the Craig section averaged a little higher (3500/mile) in the post-whirling years as compared to the pre-whirling years (2600/mile). Pre- and post-whirling numbers of the core population of adult rainbows (14 – 17 inches) were nearly identical at 1200/mile. Most surprisingly, numbers of “trophy” rainbows (17 inches and longer) were dramatically higher in the post-whirling years (1700/mile) as compared to only 500/mile in the pre-whirling years. To be honest, we are not entirely sure how the river’s rainbow population is managing to hold on so well, but it is pleasing to see. Biological systems are very complex, and there is often more at play than meets the eye. There are many possible explanations, including improved survival due to lower density of young fish, improved growth, seasonal fish movements, development of immunity, better production from whirling disease-free areas, changes in fishing regulations and harvest, and others.

FWP has a second long-term trout population monitoring section on the Missouri, located around the Pelican Point Fishing Access Site, about 6 miles upstream from the town of Cascade. Young rainbows produced for this section come mostly from the Dearborn River and Sheep Creek. The Dearborn first became heavily infected with whirling disease in 2004, while Sheep Creek has remained uninfected or only lightly infected over the years. Potentially, yearling rainbow numbers in the Pelican Point section should have been adversely affected by the Dearborn infection, and we should have noticed this in our 2005 and 2006 population estimates. It does appear yearling rainbow numbers have been down a bit the past two years, but they are still averaging 80% of the pre-whirling average, which is encouraging. It will take several more years of monitoring to get a clear picture of effects in the Pelican Point area.

Brown trout are also monitored in these two long-term fish population monitoring sections on the river. In general, brown trout numbers have historically been much lower than rainbows, and their populations do not appear to fluctuate as much. Brown trout are relatively immune to whirling disease because they co-evolved with the parasite in their native waters in Europe. Missouri River brown trout populations have been relatively stable over the years and do not appear to have been influenced one way or the other by whirling disease. The 2006 estimate for the Craig section was about 600 browns per mile 10 inches and longer, which was slightly higher than the long-term average. There were about 250 brown trout per mile in the Pelican Point section in 2006, which was slightly below the long-term average for that section.