Montana's Fish Species of Special Concern

Sturgeon chub

William R. Gould  

Biology Department  

Montana State University

Bozeman, Montana 59717-0346

June, 1998  

  Status

The sturgeon chub (Macrhybopsis gelida) is widespread and commonly found in eastern Montana.  The sturgeon chub  is classified as a Montana species of special concern (Class B) because at one time it was perceived to have limited numbers and/or habitats (Hunter 1994).  More recent collections have found this species is distributed over some 650 km of the Missouri, Yellowstone and Powder rivers in Montana and in greater numbers than previously reported.  This wide range protects this species from a potential catastrophic event that could eliminate it from the state. For these reasons sturgeon chub appear to be relatively secure in Montana.

Sturgeon chub populations in downstream states may not be as secure as found in Montana.  On August 8, 1994, the USFWS was petitioned by conservation groups to list the sturgeon chub as an endangered species.  The USFWS reviewed available information and concluded that substantial information existed to indicate that listing of the sturgeon chub as endangered may be warranted (Federal Register, Vol. 60, No. 11, 3613-3615; Dec 29, 1994).  Presently, the sturgeon chub is Catagory 2 species, with a Tier 3 listing priority, and a final decision for recommending listing may be announced by the USFWS in 1999.    

Distribution

The sturgeon chub is indigenous to the Missouri-Mississippi river basins from Montana to Louisiana (Lee et al. 1980; Werdon 1993).  Historically, sturgeon chub have been collected in small numbers from only a few locations in Montana so the Montana Department of Fish, Wildlife and Parks designated it a state species of special concern over two decades ago (Holton 1980).  More recently, Werdon (1993) reported the sturgeon chub was in possible danger of extinction over much of its former range, including all relevant Montana waters except the Powder River.  However, recent collections of this species show it is more widespread and abundant than previously understood.  Prior to 1975 only four collections of sturgeon chub were known from Montana.  The first collection was taken from an unknown site on the Milk River (Girard 1856) and three collections were reported over 100 years later from the Yellowstone River drainage (Bailey and Allum 1962; Brown 1971).  Collections from 1975-1982 determined that chubs were also present throughout the Powder River (Rehwinkle 1978), in the lower Tongue River 1980), in the lower Teton and the middle Missouri rivers (Gardner and Berg 1982).

During the Period 1990-95, collections have verified the persistence of sturgeon chub in much of their previously known range and established major range extensions.  The most recent compilation of sturgeon chub distribution in Montana is shown in Figure 5.  Sturgeon chub are still present in the Powder River (Werdon 1993; Gould 1994), lower Yellowstone River (Werdon 1993; 1994 MSU collections by Bramblett et al.) and mid-Missouri River (1994 MSU collections by Gardner and Grisak).  Furthermore, collections from 1993 - 1995 have yielded significant up and down-stream range extensions in the lower Yellowstone (MSU collections by Bramblett et al., Ruggles 1997 and Stewart 1994), mid-Missouri (MSU collections by Gardner and Grisak) and the lower Missouri rivers (Tews 1993 and Ruggles 1997).  In total, recent sturgeon chub have been found over some 650 km in three Montana rivers (Gould 1994).  However, sampling has not been able to establish their continued existence in the lower Teton, Milk and Tongue rivers (Gould 1994).

Figure 5.  Distribution of sturgeon chub in Montana, 1990-97.

Life History/Ecology

The biology of sturgeon chub is not well known.  It apparently spawns from June through July (Lee et al. 1980; Stewart 1981; Werdon 1992; Gould 1994).  Ripe fish have been found in waters of about 18-25 C� (Cross 1967; Werdon 1992; Gould 1994).  Sexual maturity is obtained by age 2 at sizes of about 76 mm total length (Stewart 1981; Werdon 1992).  Average lengths at ages 1 through 3 were calculated to be 48, 69 and 80 mm respectively (Werdon 1992).  Apparently few fish reach age 4 (Stewart 1981).

Sturgeon chub are highly adapted to life in turbid waters.  They have small eyes and many external papillae on their bodies and fins, probably to aid in locating food (Cross 1967, Pflieger 1975).  Chub are most closely associated with sites having moderate currents and depths and sand or rock substrates (Baxter and Simon 1970; Brown 1971; Lee et al. 1980).  In the Powder River, sturgeon chub were taken most frequently at sites with depths less than 51 cm and depth velocities of less than 90 cm/s at 0.6 depth (Stewart 1981; Werdon 1992; Gould unpublished data).

Populations

Sturgeon chub have been classified as uncommon or rare in Montana because (until recently) they were collected infrequently and then only in small numbers (Brown 1971; Elser et al. 1977; Elser et al. 1980; Holton 1980; Werdon 1993).  Nevertheless sturgeon chub have been collected frequently in the Powder River (Rehwinkel 1978) including three Powder River collections made during 1993 and 1994 where catches averaged 15 or more specimens (Gould 1994). Sturgeon chub are also reported as being common in portions of the middle Missouri (Gardner 1995), lower Missouri and Yellowstone rivers (Ruggles 1997).  These recent collections of relatively high numbers of sturgeon chub have shown them to be more numerous at some sites in Montana than previously believed.  It seems highly likely that additional sites with relatively high numbers of specimens will be discovered in the next few years with the increased collecting efforts being devoted to this species and the use of trawling as a new collection technique.

The U.S. Fish and Wildlife Service's recent status report states sturgeon chub may be in danger of extinction in pertinent Montana waters except in the Powder River (Werdon 1993).  This evaluation appears to be based largely on the beliefs that sturgeon chubs in Montana had a limited distribution and probable recruitment problems.  These appraisals were derived largely from the results of a federal study on the Powder and lower Yellowstone rivers in 1989 and 1990 (Werdon 1993).

But, more recent Montana collections show the sturgeon chub is much more widely distributed than considered in the 1993 federal status report.  Collections in 1993 and 1994 found sturgeon chub at sites 144 km farther downstream in the Yellowstone River and over a 135 km reach of the Missouri River that were not included in that analysis.  Thus the recent total range of sturgeon chub is at least 650 km in three Montana rivers.

These same recent collections also show recruitment is occurring in these three Montana rivers.  Collections from the Missouri and Yellowstone rivers contain both adult and immature specimens proving recruitment is occurring there and although the few specimens collected from the Powder River in 1994 were all adults, their very presence and reproductive condition strongly indicates recruitment there since 1990 as few chubs live more than 3 years (Stewart 1981).

Threats

The major threats to the sturgeon chub is thought to be habitat alteration by dam operations and irrigation operations and development.   Chubs need riffles and runs in turbid shallow waters or deeper running waters.  The pools created behind dams have innundated riverine habitats and replaced the river with lake conditions, which is probably unsuitable habitat for chubs.  Dams also may create unsuitable habitat for chubs in downstream waters by reducing turbidities and/or altering temperature and flow regimes.  Fortunately for this species, it appears unlikely that any new dam will be built on the Powder, Yellowstone or Missouri rivers in Montana in the foreseeable future. However, water regulation at Fort Peck Dam and several other tributary dams continue to limit the distribution and abundance of chub populations in Montana.

Low stream flows probably have eliminated some peripheral sturgeon chub populations in smaller streams such as the lower Teton, Milk and Tongue rivers but dewatering poses little threat to the core populations of chubs in the Missouri and Yellowstone rivers.  This species has persisted in the Powder, Yellowstone and Missouri rivers during the recent years of drought in Montana.  Also instream flow reservations provide some protection from extreme dewatering in the core habitats of chubs.

Irrigation projects are fairly numerous on the lower Missouri, Yellowstone, Bighorn, Tongue and Milk rivers and and there are numerous potential problems that could harm sturgeon chub populations if proper safe guards are not provided.  Currently none of the larger irrigation intake structures in these rivers are screened for preventing fish loss.  Hiebert et al (1999) found that a high number of sturgeon chub were entrained in the large Intake Diversion Canal on the lower Yellowstone River.  Other irrigation associated threats are dewatering and cross-channel diversion dams that block passage and fragment populations. 

Management

The management of this species should involve routine monitoring (once every 2-3 years) of existing populations.  The program should be designed to monitor population trends, range expansion or losses and collect additional information on life history and ecology.  This could be conducted while sampling for other species.   Recommendations for operating reservoir and irrigation projects should be developed for improving and maintaining sturgeon chub populations and habitats in Montana.   Reintroduction of sturgeon chub should be considered for the lower Teton, Milk and Tongue rivers.

References

Bailey, R. and M. Allum.  1962.  Fishes of South Dakota.  Museum of Zoology, University of Michigan.  Ann Arbor.

Baxter, G. and J. Simon.  1970.  Wyoming fishers.  Bulletin Number 4, Wyoming Game and Fish Department.  Cheyenne.

Brown, C. 1976. Fishes of Montana.  Big Sky Books, Montana State University.  Bozeman.

Cross, F.  1967.  Handbook of fishes of Kansas. Museum of Natural History, University of Kansas.  Lawrence, Kansas.

Elser A. et al. 1977.  The effect of altered streamflow on fish of the Yellowstone and Tongue Rivers, Montana.  Technical Report No. 8, Yellowstone Impact Study, for the old west Regional Commission.  Helena.

Elser, A. et al.  1980.  Distribution of fishes in southeastern Montana.  Report submitted to the Bureau of Land Management.  Miles City.

Gardner, W. M. and R. Berg.  1982.  An analysis of the instream flow requirements for selected fishes in the wild and scenic portion of the Missouri River.  Montana Fish Wildlife and Parks.  Helena.  111pp.

____________.  1995.  Northcentral Montana Fisheries Study, Missouri River pallid sturgeon inventory.  Mont. Fish Wildlife and Parks.  Helena.  Fed. Aid to Fish and Wildlife Rest. Proj. F-46-R-8.  Study No. III, Job D.  13pp.

Girard, C. 1856.  Researches upon the cyprinoid fishes inhabiting the fresh waters of the United States, west of the Mississippi Valley, from specimens in the museum of the Smithsonian Institution.  Proceedings of the Academy of Natural Science of Philadelphia. 8: 165-213.

Gould, W.  1994.  The recent distribution of sturgeon chub (Macrhybopsis gelida) in Montana.  Report to the Montana Department of Fish, Wildlife and Parks. Helena.

Hiebert, S. D., R. Wydoski and T.J. Parks.  1999.  Fish entrainment at the lower Yellowstone Diversion Dam, Intake Canal, Montana - 1996-1998.  Technical Service Center Data Report.  Bureau of Reclamation.  In press.  52 pp.

Hunter, C. 1994.  Species of special concern list updated. Montana Outdoors, September/October: 32-33.

Holton, G. 1980.  The riddle of existence; fishes of special concern. Montana Outdoors  11: 2-6.

Lee, S. et al.  1980.  Atlas of North American freshwater fishes.  North Carolina State Museum of Natural History.  Raleigh.

Pflieger, W. 1975.  The fishes of Missouri.  Missouri Department of Conservation.   Jefferson City, Missouri.

Rehwinkle, B.  1978.  Powder River aquatic ecology project.  Report to Utah International, Inc. Salt Lake City.

Ruggles, M.P.  1997.  Sections 2 & 3:  Upper Inter-Reservoir I and Lower Yellowstone River, Montana.  in D.J. Dieterman, M.P. Ruggles, M.L. Wildhaber, and D.L. Galat, editors.  Population structure and habitat use of benthic fishes along the Missouri and Lower Yellowstone Rivers.  1997 Annual Report of Missouri River Benthic Fish Study PD-95-5832 to U.S. Army Corps of Engineers and U.S. Bureau of Reclamation.

Stewart, D.  1981.  The biology of the sturgeon chub (Hybopsis gelida Girard) in Wyoming.  Masters Thesis.  University of Wyoming. Laramie.

Stewart, P.A.  1994.  Survey and inventory of warmwater streams.  Southeast Montana warmwater streams investigations.  Montana Fish Wildlife and Parks.  Helena.  Fed. Aid to Fish and Wildlife Rest. Job Prog. Repr. F-46-R-7, Job III-B.  10 pp.

Tews A. 1993.  Pallid sturgeon and shovelnose sturgeon in the Missouri River from Fort Peck Dam to Lake Sakakawea and in the Yellowstone from Intake to its mouth.  Report submitted to the U.S. Army Corps of Engineers.  Planning Branch. Omaha.

Werdon, S. 1992. Population status and characteristics of Macrhybopsis gelida, Platygobio gracilis and Rhinichthyes cataractae in the Missouri river Basin.  Masters Thesis.  South Dakota State University.  Brookings.

Werdon, S.  1993.  Status report on sturgeon chub (Macrhybopsis gelida), a candidate endangered species.  U.S. Fish and Wildlife Service, Ecological Services, North Dakota State Office. Bismarck.