The study of the fishes in the entire 2,300 miles of the main stem (exclusive of reservoirs) Missouri River might be one of the largest river fisheries studies conducted. The focus of this 4-year study was the benthic fish guild, which is a group of 26 species of bottom-associated fish.

In this guild are native fishes that may be jeopardized by past and present management of the Missouri River. The guild includes the endangered pallid sturgeon. Species that are possibly declining are the blue sucker, western silvery minnow, plains minnow, sturgeon chub, sicklefin chug, flathead chub, and shovelnose sturgeon. Also in the guild are recreational fishes such as the channel catfish and paddlefish, and keystone fishes thought to be important to river ecology. There are about 89 fish taxa listed as present in the Missouri main stem.
 

A suite of physical and hydrological measurements (e.g. velocity, depth, substrate type, bottom contour) were made at each fish collection site. In 18 segments throughout the river, fish were sampled in six macrohabitats (inside and outside bends of crossovers, main-channel crossovers, secondary channels that were either connected or unconnected to the main channel, and tributary confluences).

 

A system-wide analysis of fish population status linked with measurements of the river habitat could be useful to river managers. For example, the data might allow predictions of how water management, construction projects, or maintenance of channel and flood control structures can help conserve fish and their habitats while maintaining public uses. Physical factors associated with healthy populations of fishes in one section of the river may provide the best model for conservation in other sections.

Objectives:

1. Describe and evaluate recruitment, growth, size structure, condition, and relative abundance of selected benthic fishes among study segments and sections;
2. Describe habitat use of benthic fishes for dominant benthic macrohabitats; and
3. Measure physical (e.g. velocity, depth) and water quality (e.g. turbidity, temperature) features in dominant habitats where fishes are collected.

Some preconceptions about the relationships between benthic fish and river habitat that were examined:

*    Population structure (i.e. recruitment, growth, age structure, size structure, body condition, relative abundance) of the benthic fishes will vary among river segments because conditions imposed by latitude (growing season), biotic community interactions (food webs), or habitat perturbations (impoundment, channelization). For example, recruitment will be more consistent in segments that resemble the natural river structure and hydrology that in perturbed segments.

*     Target benthic fishes will vary in their use of the six dominant macrohabitats. For example, fishes using the main channel will vary among segments, and the occurrence of main channel species will decrease with increased hydrologic and physical modification.

The Missouri River system: Originating in the Rocky Mountains of south central Montana, the Missouri River flows 2,300 miles through seven states, ending at its confluence with the Mississippi River near St. Louis, Missouri. Today the river is a highly regulated system that is vastly different from past conditions. Along its upper course are seven federal, main-stem reservoirs that have submerged about a third of the former river under permanent pools. Remnants of the former river exist below some of the dams but are subject to highly modified flow regimes. The lower third of the river now consists largely of a constricted, rock-lined, single channel.

The river serves as a point of focus for the Basin's economy. The Corps of Engineers operates the river system for interests that include flood control, navigation, irrigation, hydroelectric power generation, municipal and industrial water, maintenance of water quality, recreation, and fish and wildlife conservation.

Unique approach: Research was conducted by six Cooperative Fish and Wildlife Research Units, which are stations in the U.S. Geological Survey's Biological Resources Division. Montana Department of Fish, Wildlife, and Parks also supplied a field team. Located at Universities in Missouri, Kansas, Iowa, South Dakota, Montana and Idaho, the Consortium of Cooperative Research Units reduced the costs of such large-scale research because of simplified logistics, established lines of communication, use of Graduate Research Assistants, and cost-sharing by each University.

Each field team conducted all work using the same protocols, which were detailed in the project's 2-volume set of standard operating procedures. All sampling was done when river temperatures were highest in a particular river section, thus reducing temporal variability in the basin-wide data set. The sampling period was generally from July through September, when the majority of the young-of-the year fishes had been recruited to the gears, flows were generally low, and all macrohabitats were usually present. All fish were identified and enumerated, but length and weight were measured only on the benthic guild species. Age and growth were determined for benthid species marked with an asterisk (*) in the list above.

Information management and statistical consultation was done by the USGS's Midwest Science Center in Columbia, Missouri. Their role assured independent standardization and consistency in data collection and analysis among all researchers. Center scientists implemented the information management plan, coordinated field data records, set standards for data processing and storage, conducted internal quality control checks, populated the database, and conducted preliminary statistical analysis. The data will be available on the World Wide Web when released.

Each of six Graduate Research Assistants are pursuing doctoral dissertations, and are using information collected during the study to address objectives beyond those of the basic study. The working hypotheses of the six dissertations are:

• River modifications cause a shift from specialized to generalized fish feeding and reproductive behaviors
• River modifications cause niche overlap among members of the sucker family (e.g. white sucker, blue sucker)
• River modifications influence morphological and physiological characters of minnows (e.g. emerald shiner)
• Flow variability and predictability are related to fish abundance, growth, and condition.
• Growth and survival of young freshwater drum are influenced by spatial and temporal variation in physicochemical characteristics
• Habitats variables can be used to predict sicklefin chub relative abundance, body condition, and growth

Results to date (6/01):

Fieldwork on the benthic fishes study was completed in 1998 with 100% success.  We collected 113,997 identifiable fish.  We collected 77,169 benthic species including four endangered pallid sturgeons. 

Nine introduced species (e.g. grass carp, bighead carp, rainbow smelt, white bass) and two hybrids were collected. Flows were higher than normal in 1996, however, 98% of the planned work was accomplished. High flow conditions were again present in 1997. The discharge at Gavins Point Dam was three times higher than normal (about 62,000 cfs).

Seining produced 50% of the catch, electrofishing 37%.  The benthic trawl and drifting trammel nets were selective for deep mid-channel habitats and produced some of the largest catches of sicklefin chubs and sturgeon chubs ever.  Analysis of habitat provides the most standardized, comprehensive, and robust synthesis of aquatic physical habitat within a spatial framework ever assembled for the Missouri River and its largest tributary. 

The South Dakota Cooperative Research Unit worked on segments of the river that are National Recreational River reaches administered by the National Park Service.  We sampled the 45-mile-long reach from Ft. Randall to Lewis and Clark Lake, and the 57-mile-long reach from Gavins Point Dam to Ponca, Nebraska.  Ph.D. student Bradley Young collected emerald shiners from throughout the basin to address a research frontier in ecology (BioScience 51(1):17), which deals with evolutionary and historical determinants of ecological processes.  His dissertation titled "Intraspecific variation among emerald shiners (Notropis atherinoides) of the Missouri River" is available from the Department.  He concluded that selective pressures in different habitats can cause changes in morphometric and meristic characters, but are probably attributable to local adaptive plasticity rather than genetic drift resulting from sub-population formation.

For preliminary analysis, data were partitioned into three major river areas:

1. Upper Missouri and Yellowstone river segments where few modifications to the river have been made
2. Interreservoir segments modified by impoundments and dams
3. Lower river segments modified by impoundments for navigation have been greatest

                    River area         Velocity          Depth           Clarity

                    Upper river           low              shallow            clear
                    Inter-reservoir      low                deep               clear
                    Lower river          low                deep               turbid

 Preliminary data on the shovelnose sturgeon can be used to illustrate the unique and interesting information that will come from this study. In the upper river sections, most shovelnose sturgeon were found where water velocities were about 1 m/s. This velocity was commonly found in all three main channel habitats (outside bends, channel crossovers, and inside bends) in the least impacted sections. However, in the lower river, 1 m/s velocities are usually exceeded in the main channel and outside bend macrohabitats, leaving only the inside bend macrohabitat to provide the velocities where most shovelnose were collected. Does the data suggest that there is reduced habitat suitability in the lower reaches for shovelnose, and that the reduced suitability changes fish fitness? Perhaps. The condition of shovelnose was higher in the upper river segments than at the inter-reservoir and lower river sites, as might be expected where habitat is limiting.

Examples of the many preliminary, species-specific results are the following:

1. Flathead chubs made up to 35% of the sample in the upper river sections, but only 6 specimens of the 2,882 fish chubs collected were collected at lower river sections.
2. Relative weight of channel catfish is 12% lower at most interreservoir and lower river sites than at the upper Missouri and Yellowstone River sites.
3. Body condition of river carp sucker, common carp, channel catfish, and shovelnose sturgeon, decreases in the downstream direction until the confluence with the Platte River where body condition begins to improve.
4. Growth rate of fish like the freshwater drum decreases in the downstream direction whereas that of the river carp sucker does not.

Publications:

The final report to the Corps of Engineers and other agencies is in the form of 12 volumes: six are PhD dissertations, and six address study goals.  The final funding amounted to $2.75 million from six Universities, four Federal agencies and four state agencies.  The project ends on July 30, 2001.

Literature about the Missouri River has been categorized into four periods.  To 1880, explorers kept notes on their impressions of the river.  Between 1880 and 1920, anthropologists wrote about settlement and the vanishing Indian presence.  Between 1944 and 1960 authors promoted the building of dams and channelization structures.  The final period of writing began in 1970 and continues to this day.  It is characterized by a plethora of scientific studies.  Volume I of our report provides an overview of the study, with a focus on the history of the study, and administration, communication, standard operating procedures, and data management.  We review 1) historical fisheries surveys, 2) information on ecology of 26 benthic fishes chosen for study, and 3) ongoing studies related to fisheries.

Other Volumes of the final report give results and discuss habitat conditions (Volume II), fish distribution (Volume III), growth, condition and recruitment of selected populations (Volume IV), what it all means (Volume V), and data (Volume VI).  A unique aspect of the study was the six PhD Dissertations that were written by students working on the study for each Coop Unit.  Each Dissertation is directly related to findings presented in Volumes I-VI.  Dissertation topics are 1) index of biotic integrity for the Missouri River, 2) niche relations of the catostomid (sucker) family, 3) variation in emerald shiners from the river and from reservoirs, 4) effects of hydrological variation on fish, 5) latitudinal variation in factors associated with fish growth, and 6) abiotic factors related to sicklefin chub distribution.  A 20-page semi-technical overview of the findings is being produced as a Bulletin from the SDSU Agriculture Experiment Station (planned availability July, 2001).

Funding Sponsors:

The study was initiated by the Corps on Engineers, which remains the chief sponsoring agency. However, several other agencies have contributed because of the potential value of the data to their interests.
 

Iowa State University   US Bureau of Reclamation  US Fish and Wildlife Service  US Geological Survey  University of Missouri  Kansas State University  Iowa Dept. Natural Resources

North Dakota Game and Fish  South Dakota State University  University of Idaho  Montana State University  Kansas Dept. Wildlife and Parks  Environmental Protection Agency  Missouri Dept. of Conversation

For more information:

Scientific direction of the study is being coordinated by Dr. David Galat (573-882-9426), Assistant Leader of Missouri Coop Unit, with input from Dr. Robert White (Montana Coop Unit), Dr. Charles Berry (SD Coop Unit), Dr. Chris Guy (Kansas Coop Unit), Dr. Clay Pierce (Iowa Coop Unit), Dr. Mark Wildhaber (Midwest Science Center), Ms. Linda Sappington (Midwest Science Center), Dr. Dennis Scarnecchia (University of Idaho), and Mr. Mike Ruggles (Montana Fish, Wildlife and Parks).

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