U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2015–5145

Prepared in cooperation with the Missouri River Recovery—Integrated Science Program, 

U.S. Army Corps of Engineers, Yankton, South Dakota

Ecological Requirements for Pallid Sturgeon Reproduction 

and Recruitment in the Missouri River—A Synthesis of 

Science, 2005 to 2012
A B

C

E D

Cover photographs. A, LANDSAT TM image of the area around the confluence of the Missouri and Yellowstone Rivers on November 

11, 2013. B, High resolution multibeam depth data and pallid sturgeon telemetry locations near the confluence of the Missouri and 

Osage Rivers. C, A researcher lowers an ichthyoplankton sampling net into the Missouri River near St. Charles, Missouri (photograph 

by David Combs, U.S. Geological Survey, May 2012). D, Microscopic image of sturgeon larva collected near the confluence of the 

Missouri and Mississippi Rivers during 2012 (photograph by Amy George, U.S. Geological Survey, July 2012). E, USGS biologists 

drift trammel nets on the Yellowstone River near Fairview, Montana to capture pallid sturgeon (photograph by Aaron DeLonay, 

U.S. Geological Survey, June 2012).
Ecological Requirements for Pallid 

Sturgeon Reproduction and Recruitment 

in the Missouri River—A Synthesis of 

Science, 2005 to 2012

By Aaron J. DeLonay, Kimberly A. Chojnacki, Robert B. Jacobson, 

Janice L. Albers, Patrick J. Braaten, Edward A. Bulliner, Caroline M. Elliott, 

Susannah O. Erwin, David B. Fuller, Justin D. Haas, Hallie L. A. Ladd, 

Gerald E. Mestl, Diana M. Papoulias, Mark. L. Wildhaber

Prepared in cooperation with the Missouri River Recovery—Integrated Science 

Program, U.S. Army Corps of Engineers, Yankton, South Dakota

Scientific Investigations Report 2015–5145

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod/.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

DeLonay, A.J., Chojnacki, K.A., Jacobson, R.B., Albers, J.L., Braaten, P.J., Bulliner, E.A., Elliott, C.M., Erwin, S.O., 

Fuller, D.B., Haas, J.D., Ladd, H.L.A., Mestl, G.E., Papoulias, D.M., and Wildhaber, M.L., 2016, Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River—A synthesis of science, 2005 to 2012: 

U.S. Geological Survey Scientific Investigations Report 2015–5145, 224 p. with appendixes, 

http://dx.doi.org/10.3133/sir20155145.

ISSN 2328-0328 (online)
iii

Contents

Acknowledgments......................................................................................................................................xiv

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Scope and Objectives for This Report...............................................................................................2

The Pallid Sturgeon .......................................................................................................................................3

Geographic Range and Historic Abundance ...................................................................................7

Reasons for Decline and Listing.........................................................................................................8

Current Population Status ...................................................................................................................8

Population Structure ............................................................................................................................9

Recovery Strategy ................................................................................................................................9

Missouri River Management Context.........................................................................................................9

Geography..............................................................................................................................................9

History of Alteration............................................................................................................................10

Missouri River Restoration Programs .............................................................................................13

The Comprehensive Sturgeon Research Project...................................................................................14

Comprehensive Sturgeon Research Project Approach...............................................................15

Pallid Sturgeon Conceptual Life-Stage Model ..............................................................................15

Sturgeon Habitat Variability within the Missouri River .........................................................................17

Yellowstone River................................................................................................................................17

Upper Missouri River..........................................................................................................................22

Lower Missouri River.........................................................................................................................24

Comparative Physical Differences among Study Sections .........................................................34

Comparative Differences among Study Years ...............................................................................35

Adult Life Stage............................................................................................................................................40

Habitat Requirements for Adult Reproductive Fish.......................................................................40

Movement and Spawning Migration......................................................................................40

Spawning Habitat ......................................................................................................................49

Long-Term Patterns of Habitat Use.........................................................................................63

Connectivity and the Importance of Tributaries ...................................................................64

Spawning Periodicity and Readiness to Spawn...................................................................67

Contaminants in Reproductive Ecology of Pallid Sturgeon ................................................72

Population Augmentation..................................................................................................................80

Flow Regime Management ...............................................................................................................81

Channel Re-Engineering....................................................................................................................82

Embryo Life Stage........................................................................................................................................82

Habitat Requirements for Embryos..................................................................................................82

Flow Regime Management ...............................................................................................................83

Channel Re-Engineering....................................................................................................................86

Free-Embryo Life Stage...............................................................................................................................86

Habitat Requirements for Hatch to Free Embryo...........................................................................86

Immediate Drift and Interstitial Hiding Hypotheses.............................................................86

Drifting Phase.............................................................................................................................88

Settling Phase ............................................................................................................................90
iv

Flow Regime Management ...............................................................................................................91

Channel Re-Engineering....................................................................................................................91

Larval Life Stage...........................................................................................................................................92

Habitat Requirements ........................................................................................................................92

Population Augmentation..................................................................................................................95

Flow Regime Management ...............................................................................................................95

Channel Re-Engineering....................................................................................................................95

Juvenile Life Stage ......................................................................................................................................96

Habitat Requirements ........................................................................................................................96

Competition.................................................................................................................................98

Survival of Juveniles .................................................................................................................99

Population Augmentation Management.........................................................................................99

Flow Regime.......................................................................................................................................100

Channel Re-Engineering..................................................................................................................100

State of Scientific Understanding of Pallid Sturgeon Ecological Requirements and

Implications for River and Species Management ..................................................................100

Landscape Scale Genetics .............................................................................................................100

State of Understanding...........................................................................................................100

Information Gaps .....................................................................................................................101

Information Needs...................................................................................................................101

Reproductive Adults and the Spawning Population ...................................................................101

State of Understanding...........................................................................................................102

Information Gaps .....................................................................................................................102

Information Needs...................................................................................................................103

Early Life-Stage Limitations—Spawn, Fertilization, Hatch, Drift ..............................................103

State of Understanding...........................................................................................................104

Information Gaps .....................................................................................................................104

Information Needs...................................................................................................................105

Young-of-Year to Juvenile ...............................................................................................................105

State of Understanding...........................................................................................................105

Information Gaps .....................................................................................................................105

Information Needs...................................................................................................................106

Role of Management Actions .........................................................................................................106

Population Augmentation.......................................................................................................106

Flow Regime..............................................................................................................................106

Channel Engineering ...............................................................................................................107

Synergies...................................................................................................................................108

Strategies for Addressing Key Information Gaps........................................................................108

Conclusions—Synthesis of Reproductive Ecology of the Pallid Sturgeon in the 

Missouri River...............................................................................................................................109

Landscape Scale Genetics .............................................................................................................109

River Management and Population Dynamics ............................................................................109

Spawning Habitat and Cues...................................................................................................110

Free-Embryo and Larval Dispersal, Retention, and Channel Morphology .....................111

Food Availability and Channel Morphology.........................................................................111

Future Information Needs ...............................................................................................................111
v

References Cited........................................................................................................................................111

Appendix 1. Reproductive Movements and Spawning, Lower Missouri River, 2012..................126

Appendix 2. Examination of Pallid Sturgeon Use, Migrations, and Spawning in the 

Milk River and Missouri River downstream from Fort Peck Dam during 2012...................136

Appendix 3. Mapping and Quantifying Spawning and Larval Habitats, Lower Missouri 

and Yellowstone Rivers, 2012 .....................................................................................................141

Appendix 4. Migration Pathways, Habitat Use, and Reproduction of Pallid Sturgeon 

in the Yellowstone River, 2012 ....................................................................................................151

Appendix 5. Adult Pallid Sturgeon Blood Chemistry ........................................................................182

Appendix 6. Free-Embryo Drift Experiments in an Experimental Stream......................................191

Appendix 7. Field Studies of Scaphirhynchus Sturgeon Embryo, Larvae, and

Young-of-Year Dispersal, Distribution, and Habitat Use in the Lower Missouri River......198

Appendix 8. Influence of Channel Morphology and Flow Regime on Free-Embryo Drift of

Pallid Sturgeon in the Lower Missouri River...........................................................................216

Figures

1. Maps showing historical and contemporary range of the pallid sturgeon ........................5

2. Map showing Pallid Sturgeon Recovery Management Units, Mississippi River

drainage .........................................................................................................................................6

3. Map showing Missouri River Basin and major tributary rivers with the

Comprehensive Sturgeon Research Project study areas......................................................7

4. Maps showing geographical and geological context of pallid sturgeon recovery

implementation............................................................................................................................11

5. Graphs showing variation in hydrologic alteration along the Missouri River..................12

6. Map showing modern channel overlain on historical channel map, Lower

Missouri River at Hermann, Missouri......................................................................................13

7. Graph showing cumulative number of peer-reviewed scientific articles and

reports related to pallid sturgeon biology, ecology, and habitat, 1970–2012....................14

8. Diagram showing simplified conceptual life-stage model for pallid sturgeon ................16

9. Map showing location of Upper Missouri River and Yellowstone River study 

sections ........................................................................................................................................17

10. Map showing representative channel morphology in the Yellowstone study 

section ..........................................................................................................................................18

11. Box plots showing suspended sediment concentrations, Yellowstone River at 

Sidney, Montana, and Missouri River at Culbertson, Montana..........................................19

12. Graphs showing channel and island width, number of channels, valley width,

pallid sturgeon relocations and habitat data collection locations on the Lower

Yellowstone River from the Powder River to the Missouri River, Montana and

North Dakota ...............................................................................................................................20

13. Box plots showing turbidity distributions, Yellowstone River near mile 0.5 and

Missouri River near Nohly, Montana, near mile 1,590..........................................................21

14. Box plots showing temperatures from 2001 to 2012, Upper Missouri River and

Yellowstone River .......................................................................................................................21

15. Graph showing interquartile ranges of water temperatures by day of year on the

Yellowstone and Upper Missouri River from daily means, 2001–2012...............................22

16. Map showing representative channel morphology in the Upper Missouri River 

study section ...............................................................................................................................23
vi

17. Graphs showing relation between air and water temperature near Fort Peck,

Montana and Wolf Point, Montana, 63 river miles downstream ........................................24

18. Map showing Lower Missouri River main stem and major tributary rivers within

the Comprehensive Sturgeon Research Project study areas.............................................25

19. Maps showing examples of channel morphological variability in the Lower

Missouri River .............................................................................................................................26

20. Graphs showing distributions of habitat variables by Lower Missouri River sections ..27

21. Maps showing natural potential spawning substrate in the Lower Missouri River .......28

22. Graphs showing channel width, flow constrictions, side channel locations, valley

width and pallid sturgeon relocations and habitat data collection locations on the 

channelized Lower Missouri River from Sioux City, Iowa, to St. Louis, Missouri............30

23. Graphs showing relation between air and water temperature in the Missouri

River near Yankton, South Dakota ...........................................................................................31

24. Graphs showing plots of discharge from Gavins Point Dam and air and water

temperature measured at Yankton, South Dakota, by year, 2006–12.................................32

25. Box plots showing seasonal water-temperature distributions at sites on the

Lower Missouri River from 2005 to 2012 .................................................................................33

26. Graph showing example of water-quality variation at Hermann, Missouri,

showing reciprocal relation of dissolved oxygen to discharge and turbidity ..................33

27. Graph showing annual runoff at four Missouri River system streamgages, 2005 to

2012 ...............................................................................................................................................35

28. Hydrographs and thermographs for the Upper Missouri River and Yellowstone

River, 2005–2012, water-temperature data were collected seasonally.............................36

29. Hydrographs and thermographs for the Lower Missouri River..........................................38

30. Graph showing characteristic, single-apex migration pattern of female pallid

sturgeon in the lower study section of the Lower Missouri River as illustrated by

PLS08-009.....................................................................................................................................41

31. Graph showing characteristic complex or disrupted migration pattern in the

upper study section of the Lower Missouri River as illustrated by PLS09-011 ................44

32. Graph showing fall migration followed by characteristic, single-apex spring 

migration pattern of female pallid sturgeon in the lower study section of the 

Lower Missouri River as illustrated by PLS11-007 ................................................................45

33. Graphs showing migration distance of adult pallid sturgeon tracked during the

spawn year from 2005 to 2012...................................................................................................46

34. Box plots showing mean depth of pallid sturgeon collected from retrieved data

storage tags.................................................................................................................................47

35. Graphs showing pallid sturgeon migration habitat availability and use on the

Lower Yellowstone and Lower Missouri River, 2010–12 ......................................................52

36. Map showing spawning locations of pallid sturgeon in the Lower Missouri River,

2007–12 .........................................................................................................................................54

37. Examples of high-resolution bathymetry................................................................................56

38. Bathymetric and acoustic Doppler current profiler velocity maps of reproductive

female pallid sturgeon spawning sites mapped, 2008–12....................................................57

39. Graphs showing probable pallid sturgeon spawning habitat availability and use

at the eight spawning locations mapped on the Lower Missouri River, 2008–12 ............61

40. Three-dimensional reconstruction created from high-resolution multibeam sonar

data of habitat used for spawning by female pallid sturgeon PLS09-007 .........................64

41. Map showing density of pallid sturgeon telemetry locations in the Lower Missouri

River in 2007–12, normalized for search effort.......................................................................65
vii

42. Graph showing telemetry locations of male pallid sturgeon PLS08-006 in the

Lower Missouri River illustrating annual seasonal migrations and a pattern of

affinity for specific locations ....................................................................................................66

43. Graph showing telemetry locations of male pallid sturgeon PLS07-020 in the

Lower Missouri River illustrating annual seasonal migrations and a pattern of

affinity for specific locations ....................................................................................................66

44. Map showing telemetry locations of pallid sturgeon PLS08-012 at the confluence 

of the Platte and Missouri Rivers, Nebraska .........................................................................68

45. Map showing telemetry locations of pallid sturgeon in the Osage

River and at the confluence of the Osage and Missouri Rivers, Missouri........................69

46. Graphs showing concentrations of reproductive hormones in a single female and

male pallid sturgeon from the Lower Missouri River held at Neosho National Fish

Hatchery.......................................................................................................................................70

47. Box plots showing annual changes in estradiol, testosterone, and

11-ketotestosterone measured as pg/mL in reproductive female pallid sturgeon

captured in the Lower Missouri River from 2005 to 2012 .....................................................71

48. Box plots showing annual changes in estradiol, testosterone, and

11-ketotestosterone measured as pg/mL in reproductive male pallid sturgeon

captured in the Lower Missouri River from 2005 to 2012 .....................................................73

49. Graphs showing mean reproductive hormone concentrations in noncycling adult

female and male pallid sturgeon held at Neosho National Fish Hatchery........................74

50. Box plots showing annual changes in estradiol, testosterone, and

11-ketotestosterone measured as pg/mL in nonreproductive female pallid

sturgeon captured in the Lower Missouri River from 2005 to 2012 ....................................75

51. Box plots showing annual changes in estradiol, testosterone, and

11-ketotestosterone measured as pg/mL in nonreproductive male pallid sturgeon

captured in the Lower Missouri River from 2005 to 2012 .....................................................76

52. Graphs showing concentrations of reproductive hormones in a non-ovulating

and an atretic female pallid sturgeon from the Missouri River, held at the Neosho

National Fish Hatchery ..............................................................................................................77

53. Graphs showing relation between reproductive readiness in female pallid

sturgeon from the Missouri River, hydrograph, and temperature for 3 years 2010,

2011, 2013 .....................................................................................................................................78

54. Graph showing readiness to spawn in female Missouri River pallid sturgeon, as

the ratio of 11-ketotestosterone:17-beta estradiol, to discharge and temperature

in 2011 ...........................................................................................................................................79

55. Graph showing readiness to spawn in female Missouri River pallid sturgeon, as

the ratio of 11-ketotestosterone:17-beta estradiol, to discharge and temperature

in 2012 ...........................................................................................................................................79

56. Box plots showing plasma vitellogenin concentrations in male pallid sturgeon

from below river mile 300 and above river mile 500 in the Missouri River

compared to plasma vitellogenin in female pallid sturgeon................................................80

57. Graphs showing total number of fish counted per day passing a fixed point in the

stream tank in trial 1 and trial 2 ................................................................................................88

58. Graphs showing probability density functions of velocity data collected using

acoustic Doppler current profiler at spawning location documented on April 28,

2010, near river mile 202 ............................................................................................................89

59. Graphs showing one-dimensional advection-dispersion models of free-embryo 

drift ...............................................................................................................................................90
viii

60. Box plots showing longitudinal dispersion coefficients calculated for the Lower

Missouri River from acoustic Doppler current profiler data ..............................................91

61. Map showing multibeam bathymetry near river mile 162 and U.S. Fish and

Wildlife Service age-0 sturgeon sampling trawl endpoints ................................................94

62. Graphs showing mean and standard deviation of riverine habitat characteristics

when pallid sturgeon were captured in the Pallid Sturgeon Population

Assessment Program from 2003 to 2010 .................................................................................97

63. Graphs showing proportion of time fish were active in clay and sand treatments

with food.......................................................................................................................................99

Appendix Figures

1–1. Map showing Comprehensive Sturgeon Research Project study sections and 

pallid sturgeon hatchery locations within the Lower Missouri River Basin...................127

1–2. Telemetry and archival tag data of female pallid sturgeon PLS11-007............................129

1–3. Telemetry and archival tag data of female pallid sturgeon PLS11-019............................130

1–4. Telemetry and archival tag data of female pallid sturgeon PLS09-011 ...........................131

1–5. Telemetry and archival tag data of female pallid sturgeon PLS10-023............................133

1–6. Telemetry and archival tag data of female pallid sturgeon PLS10-029 ...........................134

2–1. Map showing location of Upper Missouri River and Yellowstone River study

sections ......................................................................................................................................136

2–2. Graph showing percent of telemetered adult pallid sturgeon located in the

Missouri River above the confluence with the Yellowstone River, 2005–12...................138

3–1. Map showing depth and depth-averaged velocity for probable spawning site, 

and location of reproductive female pallid sturgeon PLS11-007 near Missouri 

River mile 322.............................................................................................................................143

3–2. Map showing depth and depth-averaged velocity for probable spawning site, 

and location of reproductive female pallid sturgeon PLS09-011 near Missouri 

River mile 580.............................................................................................................................144

3–3. Map showing depth-averaged velocity and pallid sturgeon telemetry locations 

for code 52 near Yellowstone River mile 73..........................................................................145

3–4. Map showing flow characteristics of free-embryo pallid sturgeon sampling 

locations near Missouri River mile 33.3 ................................................................................146

3–5. Telemetry locations and multibeam bathymetry showing depth at locations used

by male pallid sturgeon PLS08-006 from 2008–12 near river miles 638.5 and 582.5.......149

4–1. Graph showing percent of telemetered pallid sturgeon detected, discharge, and

mean daily water temperature of the Yellowstone River, April–August 2012.................153

4–2. Graphs showing data for five telemetered pallid sturgeon migrating to Intake

Dam on the Yellowstone River, April–August 2012..............................................................154

4–3. Graphs showing locations of telemetered male pallid sturgeon exhibiting

migrations in the Yellowstone River, April–August 2012 ....................................................155

4–4. Graphs showing mean daily locations of telemetered female pallid sturgeon

exhibiting migrations in the Yellowstone River and Missouri River upstream from

the confluence with the Yellowstone River, April–August, 2012.......................................156

4–5. Map showing migration pathway of male pallid sturgeon code 52 in the 

Yellowstone River approaching Intake Dam, June 9, 2012 ................................................158
ix

4–6. Map showing migration pathways of male pallid sturgeon codes 52 and 76 in 

the Yellowstone River approaching Intake Dam, June 9 and 22, 2012.............................159

4–7. Map showing pallid sturgeon code 42 telemetry locations in the Yellowstone 

River, April 30, 2012...................................................................................................................160

4–8. Map showing pallid sturgeon code 16 telemetry locations in the Yellowstone 

River, May 17, 2012 ...................................................................................................................161

4–9. Map showing pallid sturgeon code 51 telemetry locations in the Yellowstone 

River, May 21, 2012 ...................................................................................................................162

4–10. Map showing pallid sturgeon code 92 telemetry locations in the Yellowstone 

River, May 21, 2012 ...................................................................................................................163

4–11. Map showing pallid sturgeon codes 36 and 37 telemetry locations in the 

Yellowstone River, May 22, 2012.............................................................................................164

4–12. Map showing pallid sturgeon code 36 telemetry locations in the Yellowstone 

River, May 23, 2012 ...................................................................................................................165

4–13. Map showing pallid sturgeon code 72 telemetry locations in the Yellowstone 

River, May 23, 2012 ...................................................................................................................166

4–14. Map showing pallid sturgeon code 69 telemetry locations in the Yellowstone 

River, June 5–6, 2012 ................................................................................................................167

4–15. Map showing pallid sturgeon code 30 telemetry locations in the Yellowstone 

River, June 6, 2012 ....................................................................................................................168

4–16. Map showing pallid sturgeon code 69 telemetry locations in the Yellowstone 

River, June 7, 2012 ....................................................................................................................169

4–17. Map showing pallid sturgeon code 69 telemetry locations in the Yellowstone 

River, June 8, 2012 ....................................................................................................................170

4–18. Map showing pallid sturgeon code 30 telemetry locations in the Yellowstone 

River, June 13, 2012 ..................................................................................................................171

4–19. Map showing pallid sturgeon code 83 telemetry locations in the Yellowstone 

River, April 10–June 21, 2012...................................................................................................172

4–20. Graphs showing depths and depth-averaged velocities used by and available to

migrating pallid sturgeon, Yellowstone River, 2012.............................................................173

4–21. Migration pathway, depth, and velocity of male pallid sturgeon codes 51 and 72

in the Yellowstone River, river mile 29.5, May 21 and 23, 2012 ..........................................174

4–22. Graphs showing discharge, water temperature, and locations of gravid female

pallid sturgeon in the Yellowstone River, May–August 2012.............................................176

4–23. Map showing spawn location of female pallid sturgeon code 30 in the lower 

Yellowstone River, June 19–20, 2012......................................................................................177

5–1. Graph showing mean plasma cholesterol concentrations in pallid sturgeon ...............186

5–2. Graph showing mean plasma glucose concentrations in pallid sturgeon .....................186

5–3. Graph showing mean plasma lactate concentrations in pallid sturgeon .......................187

5–4. Graph showing mean plasma lipase concentrations in pallid sturgeon.........................188

5–5. Graph showing mean plasma total protein concentrations in pallid sturgeon..............188

5–6. Graph showing mean plasma total triglyceride concentrations in pallid sturgeon ......189

6–1. Diagram of the oval stream tank used in the free-embryo drift experiments ...............191

6–2. Graph showing relation between days post-hatch and cumulative thermal 

units calculated for trials 1–4 .................................................................................................193

6–3. Graph showing percent mortality of pallid sturgeon free embryos per days

post-hatch..................................................................................................................................195
x

6–4. Graph showing daily observations of free embryos drifting past a fixed point

normalized to the number of free embryos in the stream, 0–12 days post-hatch..........196

6–5. Graph showing frequency of free embryos near the pool ledge and dike eddy as

percent of the total number of observations during each trial .........................................196

6–6. Graph showing mean number of drifting free embryos and water column

positions recorded at a fixed point per days post-hatch...................................................197

7–1. Maps showing free-embryo sampling locations in the Lower Missouri River, 

near river mile 33.3 ...................................................................................................................200

7–2. Graph showing length of sturgeon free embryos and larvae, and mean hourly

temperature and discharge from the U.S. Geological Survey streamgage near 

St. Charles, Missouri, 2012 ......................................................................................................209

7–3. Graph showing length of paddlefish free embryos and larvae, and mean hourly

temperature and discharge from the U.S. Geological Survey streamgage near 

St. Charles, Missouri, 2012 ......................................................................................................209

8–1. Map showing Missouri River segments, U.S. Geological Survey streamgages,

and velocity measurement sites used for calculation of longitudinal dispersion

coefficients ................................................................................................................................217

8–2. Boxplots showing dispersion coefficients calculated for velocity measurement 

sites along the Lower Missouri River ...................................................................................219

8–3. Graphs showing downstream transport and dispersion of passively drifting free 

embryos using the one-dimensional advection-dispersion equation..............................221

8–4. Graph showing relation between free embryo downstream drift distance and

concentration of free embryos released at an arbitrary upstream point........................221

8–5. Graphs showing change in the longitudinal dispersion coefficient with discharge.....222

Tables

1. Pallid sturgeon life stage definitions used in this report .......................................................4

2. Probable spawning locations of telemetry tracked reproductive female pallid

sturgeon, 2007–12 .......................................................................................................................43

3. Habitat mapping data collected for reproductive pallid sturgeon in migration

study from 2010–12 .....................................................................................................................48

4. Pallid sturgeon migration pathways mapped in 2010–12.....................................................51

5. Migration habitat data summary..............................................................................................53

6. Spawning dates and discharges, 2008–12 .............................................................................55

7. Summary of water temperature, discharge, substrate, depth, depth-averaged

velocity, and turbidity at pallid sturgeon spawning sites in the Lower Missouri

River, 2008–12 ..............................................................................................................................62

8. Substrate at spawning sites interpreted from sidescan sonar and multibeam

bathymetry data, 2010–12..........................................................................................................63

9. Measures of sperm quality for milt collected from captive and wild pallid

sturgeon during 2011..................................................................................................................81

10. Minimum and maximum hourly thermal units for Scaphirhynchus sturgeon egg

development and minimum and maximum hours to completion of each stage for

18–22 degrees Celsius ...............................................................................................................84

11. Daily mortalities of pallid sturgeon free embryos in an artificial stream

tank with an average velocity of 14 centimeters per second from four separate

experimental trials......................................................................................................................87
xi

12. Effect of day post-hatch cumulative thermal units of first feeding on survival of

free-embryo pallid sturgeon reared at constant water temperature and water

temperature fluctuating in accordance with modeled lower Missouri River

temperatures during drift ..........................................................................................................93

Appendix Tables

2–1. Sampling dates and paddlefish, shovelnose sturgeon, and pallid sturgeon free

embryos and larvae collected in the Missouri River near Wolf Point, Montana, in

2012 .............................................................................................................................................138

2–2. Total catch of fish by the benthic trawl in the Missouri River above the

confluence of the Yellowstone River, Missouri River below the confluence of the

Yellowstone River, and total catch from July 24 to September 11, 2012..........................139

2–3. Catch of shovelnose sturgeon in standard trawls and targeted trawls in the

Missouri River during 2012 by date........................................................................................139

3–1. Sturgeon habitat mapping 2012 data collection effort on the Missouri and

Yellowstone Rivers ...................................................................................................................147

5–1. Plasma chemistry for pallid sturgeon according to sex, reproductive state, and

whether they were captured from the wild and held in captivity for less than 1

month or held captive in the hatchery environment...........................................................183

5–2. Blood chemistry of Missouri River pallid sturgeon.............................................................184

6–1. Mean, standard deviation, and range of velocity in centimeters per second at

seven locations in three trials of the artificial stream channel ........................................194

7–1. Summary of sturgeon and paddlefish free embryo and larvae collection efforts in

the Missouri River near St. Charles, Missouri, during 2012...............................................201

7–2. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 1.......................................................................................................201

7–3. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 2.......................................................................................................202

7–4. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 3.......................................................................................................202

7–5. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 4.......................................................................................................203

7–6. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 5.......................................................................................................205

7–7. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 6.......................................................................................................207

7–8. Summary of free embryo and larval sturgeon and paddlefish collected in the

Missouri River at station 7.......................................................................................................208

7–9. Mean density, number per 100 cubic meters, of sturgeon free embryos and

larvae collected in the Missouri River per sampling day...................................................210

7–10. Mean density, number per 100 cubic meters, of paddlefish free embryos and

larvae collected in the Missouri River per sampling day...................................................212

8–1. Characteristics of Missouri River sites used to obtain data for estimating

dispersion coefficients ............................................................................................................218

8–2. Descriptive statistics for longitudinal dispersion coefficient calculated for each

measurement site in the Missouri River...............................................................................220
xii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

mile (mi) 1.609 kilometer (km)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

SI to Inch/Pound

Multiply By To obtain

Length

micrometer (μm) 0.0000397 inch (in.)

millimeter (mm) 0.03937 inch (in.)

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

meter (m) 1.094 yard (yd) 

Area

square meter (m2

) 10.76 square foot (ft2) 

hectare (ha) 0.003861 square mile (mi2

) 

square kilometer (km2

) 0.3861 square mile (mi2)

Volume

cubic meter (m3

) 264.2 gallon (gal) 

cubic meter (m3

) 35.31 cubic foot (ft3)

cubic meter (m3

) 1.308 cubic yard (yd3) 

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s) 

cubic meter per second (m3

/s) 35.31 cubic foot per second (ft3/s)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

To communicate effectively with stakeholders, managers, and other scientists working on the 

Lower Missouri River, this report uses a mix of U.S. customary units and International System of 

Units (SI) units of measure. Distances along the Missouri River are given in river miles upstream 

from the confluence with the Mississippi River at St. Louis, Missouri, as measured by the 

U.S. Army Corps of Engineers in 1960. Discharges are provided in the customary units of cubic 

feet per second. Reach-scale hydraulic variables—depth and velocity—are given in SI units of 

meters and meters per second.

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32
xiii

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the World Geodetic System of 1984 (WGS 84).
xiv

Acknowledgments

This report benefitted from technical reviews by Michael Parsley, Dr. Brenda Pracheil, and Dr. 

Hal Schramm. Funding for this research was provided by the U.S. Army Corps of Engineers, Missouri River Recovery—Integrated Science Program and the U.S. Geological Survey. The authors 

gratefully acknowledge the collaboration and cooperation of the U.S. Fish and Wildlife Service, 

Columbia Fish and Wildlife Conservation Office; U.S. Fish and Wildlife Service, Gavins Point and 

Neosho National Fish Hatcheries; Nebraska Game and Parks Commission; South Dakota Game, 

Fish, and Parks; and the Missouri Department of Conservation.
Ecological Requirements for Pallid Sturgeon Reproduction 

and Recruitment in the Missouri River—A Synthesis of 

Science, 2005 to 2012

By Aaron J. DeLonay,1 Kimberly A. Chojnacki,1 Robert B. Jacobson,1 Janice L. Albers,1 Patrick J. Braaten,1

Edward A. Bulliner,1

 Caroline M. Elliott,1 Susannah O. Erwin,1 David B. Fuller,2 Justin D. Haas,3

Hallie L. A. Ladd,4 Gerald E. Mestl,3 Diana M. Papoulias,1 and Mark. L. Wildhaber1

1

U.S. Geological Survey.

2

Montana Fish, Wildlife and Parks.

3

Nebraska Game and Parks Commission.

4

Five Rivers Services, LLC.

Abstract

This report is intended to synthesize the state of the 

scientific understanding of pallid sturgeon ecological requirements to provide recommendations for future science directions and context for Missouri River restoration and management decisions. Recruitment of pallid sturgeon has been low to 

non-existent throughout its range. Emerging understanding of 

the genetic structure of pallid sturgeon populations sets a broad 

framework for species and river management decisions, including decisions about managing the future genetic diversity of the 

species, but also decisions about where and what type of river 

restoration actions will be effective for subpopulations of this 

highly migratory species. Adult pallid sturgeon may migrate 

hundreds of kilometers (km) to spawn and their progeny may 

disperse even greater distances downstream as drifting free 

embryos. As a result of their complex life history pallid sturgeon naturally exploit a wide range of habitats during their life 

cycles. The construction of dams and reservoirs has fragmented 

habitats and may have shifted Missouri River subpopulations 

downstream. Research has not identified one primary biological or ecological constraint that appears to limit populations of 

the pallid sturgeon. With the present (2013) state of knowledge 

many life stages and life-stage transitions cannot be ruled out 

as contributing to recruitment failure.

Biological opinions in 2000 (and amended in 2003) 

presented the dominant hypotheses for recruitment failure 

that existed at that time. Emphasis was on the role of the flow 

regime, specifically spring flow pulses (“spring rises”), to condition spawning substrate and cue reproductive aggregations 

and migrations, and on low flows and additional slow, shallow-water area to serve as rearing habitat for age-0 to juvenile 

pallid sturgeon. Studies on spawning habitat dynamics have 

documented that habitat patches selected for spawning by fish 

in the Lower Missouri River (Missouri River downstream 

from Gavins Point Dam to the confluence with the Mississippi River) are dominantly on outside, revetted bends in the 

deepest, fastest, and most turbulent water. Studies in more 

natural habitat on the Yellowstone River have documented 

spawning in convergent flow in the middle of the channel on 

discrete patches of gravel within a sand-dominated channel, an 

arrangement that may be more effective in attracting aggregations of reproductive fish compared to the nearly continuous 

revetment on the Lower Missouri River. Pallid sturgeon spawn 

in the spring and early summer during periods of increasing 

day length. Water temperature consistently exerts a threshold 

effect for spawning at 16–18 °C. In addition, the role of water 

temperature is indicated by pauses and reversals in upstream 

migrations that have been associated with cold weather fronts 

that create a transient decrease in water temperature. From 

2005 to 2012 on the Lower Missouri River, no obvious relations between flow pulses and fish movements and spawning 

behaviors have been apparent. However, pallid sturgeon tracking at the Upper Missouri–Yellowstone confluence indicates 

that in most years, most telemetered pallid sturgeon migrate 

out of the Missouri River and into the Yellowstone River in 

the June–July timeframe in association with the spring pulse. 

This pattern was disrupted in 2011 when a high flow pulse 

with warm temperatures and high turbidity emanated from the 

Milk River, followed by record releases from Fort Peck Dam, 

and 36–39 percent of the telemetered population migrated 

up the Upper Missouri. This result supports the hypothesis 

that sufficiently large flow pulses may trigger migration and 

aggregation but it is not clear that functional pulses are within 

reservoir management authorities. Notably, a pallid sturgeon 

free embryo was captured on the Upper Missouri River in 

2011 and another single, genetically confirmed embryo was 

captured on the Yellowstone River in 2012.

Research on free-embryo drift has indicated the potential for hundreds of miles of downstream dispersal. Lack of 

distance to accommodate the extended downstream dispersal period of free embryos on the Upper Missouri and 
2 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Yellowstone Rivers is the predominant hypothesis for recruitment failure in the upper basin. Long drift distances in the 

Lower Missouri River may be responsible for shifting Lower 

Missouri River sub-populations further into the Middle Mississippi River. Physical understanding of drift processes indicates that mean velocities could be slowed through decreased 

discharges or increased channel hydraulic radius (width 

and topographic diversity) to reduce free-embryo dispersal 

distances. In addition, the probability that free embryos are 

transported into and retained in channel-margin habitats is 

theoretically amenable to channel re-engineering that would 

increase cross-channel secondary currents in bends or channel expansions. Considerable uncertainty persists, however, 

about whether extended drift of Lower Missouri River larvae 

is responsible for recruitment failure. If drift distance is limiting, it is important to discern whether it would be advisable to 

retain larvae within the Missouri River, and where along the 

river restoration projects should be placed to optimize survival 

and growth of age-0 and juvenile sturgeon.

Longitudinal differences in female pallid sturgeon fecundity lend support to the hypothesis that recruitment failure 

may be due, in part, to fish having insufficient nutrition to 

produce the numbers of gametes needed for the population to 

grow, perhaps because of simultaneous declines in prey-fish 

populations and their habitats. Establishing a chain of causality from habitat decline, to prey-fish populations, to sturgeon 

diets, to sturgeon fecundity, and to pallid sturgeon population 

growth presents a considerable scientific challenge.

In addition to the dominant hypotheses relating pallid 

sturgeon populations to changes in flow regime and channel 

morphology, other factors have been identified that might be 

sources of stress and contribute to recruitment failure. Among 

these are water quality and contaminants. Ambient waterquality monitoring on the Missouri River has demonstrated 

summer episodes when dissolved oxygen dips below 5 milligrams per liter, a threshold that may be stressful especially to 

age-0 and juvenile sturgeon. Documented cases of intersex in 

shovelnose and pallid sturgeon indicate that agricultural and 

municipal sources of endocrine disrupting chemicals also may 

have a role in pallid sturgeon recruitment failure.

Scientific understanding of the ecological requirements 

of pallid sturgeon has increased almost exponentially in the 

last two decades, and efforts are now turning from understanding fundamental biology of the species to quantifying how 

population dynamics relate to potential management actions. 

Progress in developing the science needed to inform management actions on the Missouri River may benefit from continuation of monitoring of reproductive cycles, reproductive 

movements, growth, and survival of telemetry tagged adults, 

increased emphasis on focused, complementary field and laboratory studies of factors influencing early life history, implementation of studies to resolve the role of food limitations in 

growth, survival, and reproductive condition, and implementation of studies designed specifically to parameterize models 

linking management to populations.

Introduction

The Comprehensive Sturgeon Research Project (CSRP) 

is designed to improve fundamental understanding of the 

reproductive ecology and population dynamics of the pallid 

sturgeon (Scaphirhynchus albus) and to facilitate application 

of scientific understanding to restoration and management 

of the species in the Missouri River system. This project is 

an interagency collaboration of the U.S. Geological Survey, 

Nebraska Game and Parks Commission (NGPC), U.S. Fish 

and Wildlife Service (USFWS), and Montana Fish, Wildlife 

and Parks (MTFWP), and is funded through the U.S. Army 

Corps of Engineers’ (USACE) Missouri River Recovery—

Integrated Science Program. Specific objectives include the 

following:

• Determine movement, habitat use, and reproductive 

behavior of pallid sturgeon;

• Understand reproductive physiology of pallid sturgeon 

and relations to environmental conditions;

• Determine origin, transport, and fate of drifting pallid 

sturgeon larvae and evaluate bottlenecks for recruitment of early life stages;

• Quantify availability and dynamics of aquatic habitats 

needed by pallid sturgeon for all life stages;

• Integrate what is known about fish distributions into 

models of survival, bioenergetics, and population 

viability;

• Manage databases, integrate understanding, and 

publish information in the public domain relevant to 

management decisions; and

• Engage with stakeholders and managers to deliver 

actionable scientific information to the adaptive management process.

Management actions to increase reproductive success 

and survival of pallid sturgeon in the Lower Missouri River 

(Missouri River downstream from Gavins Point Dam to the 

confluence with the Mississippi River) have been focused on 

naturalizing the flow regime, re-engineering channel morphology, and propagation (U.S. Fish and Wildlife Service, 2003). 

Recently (2015), management questions also have emphasized 

the possibility of constructing enhanced fish passage on the 

Yellowstone River. These management questions provide the 

context for prioritizing CSRP science efforts.

Scope and Objectives for This Report

The objective of this report is to synthesize research 

findings of the CSRP within the context of what is known 

about the ecological requirements of pallid sturgeon and their 

reproductive biology. The underlying goal is to clarify knowns 
The Pallid Sturgeon 3

and unknowns and to illustrate how the science may inform 

management decisions. In keeping with USGS policies, we 

do not make species- or river-management recommendations; 

rather, our intent is to synthesize available information in the 

context of specific management questions so managers and 

stakeholders have a better understanding of available options. 

The intended audience includes research scientists, resource 

managers, planners, and decision makers.

The science that underpins our understanding of pallid 

sturgeon biology and ecology is carried out in the broader 

setting of a highly altered, intensively managed large river 

ecosystem. The pallid sturgeon is a rare and complex species 

that relies on a single, continuous, longitudinal thread of river 

to complete its life history; it exists, and can be recovered, 

nowhere else. For this reason, we have synthesized information on the decline and recovery of the pallid sturgeon, 

the alterations and management constraints that structure 

the contemporary Missouri River, and the existing physical 

habitat template upon which pallid sturgeon restoration and 

recovery actions are implemented. Because the CSRP study 

design includes development of information from geographic 

comparisons among the Upper Missouri, Yellowstone, and 

Lower Missouri Rivers, this discussion provides critical context for the application of the scientific findings presented, and 

aids in clarifying future science directions and management 

opportunities.

In this synthesis we present discussion of pallid sturgeon 

research completed by CSRP, agency collaborators, and other 

scientists from 2005 through 2012. Results from specific studies completed in 2012 are discussed within the main text or 

presented in appendixes 1–8. We organize the analysis of the 

information by breaking scientific knowledge down by life 

stages (table 1), presenting what is known and unknown about 

those life stages, and then discussing reproduction, growth, 

and survival in terms of the three main management actions 

that have been under consideration on the Missouri River: 

population augmentation, flow-regime management, and channel re-engineering.

The Pallid Sturgeon

The pallid sturgeon was first brought to the attention of 

biologists by commercial fishermen near the confluence of 

the Missouri and Mississippi Rivers in the first decade of the 

twentieth century (Forbes and Richardson, 1905). Known 

locally as the “white sturgeon,” the pallid sturgeon was 

uncommon in catches from the Mississippi River; perhaps 

as few as 1 in 500 sturgeon caught. Forbes and Richardson 

(1905) speculated that the species had yet to be described 

because so few specimens of Scaphirhynchus sturgeon had 

been examined by Ichthyologists within the species range 

(fig. 1). The new species of sturgeon (Parascaphirhynchus 

albus) was differentiated by Forbes and Richardson (1905) 

from the more common shovelnose sturgeon (Scaphirhynchus 

platorynchus) based on the examination of nine specimens, all 

male, collected on the Mississippi River near the mouth of the 

Illinois River at Grafton, Illinois (not shown). The distinctiveness of the pallid sturgeon led Forbes and Richardson (1905) 

to assign it to a separate genus. Once described, the species 

received little attention from biologists for the next half century beyond minor disagreements and refinements concerning 

the most appropriate taxonomic assignment and nomenclature for the new species. Bailey and Cross (1954) reviewed 

and reaffirmed the distinctiveness of the pallid sturgeon and 

assigned the shovelnose sturgeon and pallid sturgeon as species within the genus, Scaphirhynchus. Bailey and Allum 

(1962) revised the specific name, Scaphirhynchus album, to 

the currently (2015) accepted designation, Scaphirhynchus 

albus.

Bailey (1954) differentiated the two sympatric species 

using meristics and morphometric ratios from a small number 

of specimens collected across the range of the species. Until 

the recent development of more effective mitochondrial DNA 

analyses (Schrey and others, 2007), identification of juvenile and adult pallid sturgeon had been largely dependent on 

metrics developed by Bailey and Cross (1954), or indices and 

analyses combining these metrics with others (Carlson and 

others, 1985; Keenlyne and others, 1994; Sheehan and others, 

1999; Wills and others, 2002; Kuhajda and others, 2005). 

While morphometric and genetic analyses have proven to be 

reasonably effective in discriminating pallid and shovelnose 

sturgeon in the Missouri River and the Middle Mississippi 

River (Mississippi River from the confluence with the Missouri River downstream to the confluence with the Ohio River; 

fig. 2) (Schrey and others, 2007), concordance between morphological and genetic discrimination of the two species on 

the Lower Mississippi River (Mississippi River downstream of 

the Ohio River confluence; fig. 2) has proven to be elusive due 

to complications arising from allometric growth, intraspecific 

geographic variation in size and age at maturity, potentially 

pervasive hybridization, and the absence of adequate genetic 

baseline data (Murphy and others, 2007; Schrey and Heist, 

2007; Schrey and others, 2011).

In contrast to the dark brown to grey shovelnose sturgeon, pallid sturgeon are more commonly pale or white to 

light grey, with coloration darkening in less turbid waters. 

Pallid sturgeon have proportionally larger mouth widths and 

smaller eyes than shovelnose sturgeon and lack the scutes or 

bony plates that fully armor the ventral surface of shovelnose’s 

abdomen (Bailey and Cross, 1954; Pflieger, 1997). Pallid sturgeon are further distinguished from shovelnose sturgeon based 

on the relative length and placement of the four fleshy barbels 

on the ventral surface of the elongated spade-shaped rostrum, 

anterior to their protrusible mouth. The inner barbels are 

reduced in pallid sturgeon. The outside barbels are 1.6 times 

the length of the inner barbels, or longer. The outside barbels 

are generally more posteriorly placed than the inner barbels 

resulting in a concave arrangement along a line parallel to the 

mouth. Barbels of the shovelnose sturgeon are more or less 

arranged in a row, with inner and outer barbels more similar 
Table 1. Pallid sturgeon life-stage definitions used in this report. Stages have been established following accepted sources. Transitions from embryo

juvenile life history stages are one way, whereas adult life history stages (pre-spawning adult, spawning adult, post-spawning adult, recrudescent adGonadal stages described from Wildhaber and others (2007b). [°C, degrees Celsius; mm, millimeters; TL, total length; FL, fork length] Life stage Definition Description Embryo A developing fish still within the chorion (egg membrane). Period from fertilization to hatch. The duration of the period is tem

ally, 5–8 days. Free embryo A developing fish no longer within a protective chorion. Period from hatch to the initiation of feeding. The duration of the p

dependent. Generally, 8 days at 22 °C to 12 days at 18 °C. Size wdependent generally 18–19 mm TL at hatch. The free embryo is yolk for nutrition and at the end of this stage transitions to exogetransition it expels its yolk plug and finishes absorbing the yolk. Larval A developing fish without yolk, feeding exogenously. Period extends from the time the fish begins to feed until it has a fu

fins. It has the appearance of an adult fish in miniature. Duration temperature- and food-dependent. May be 186 days and 205 mm 

Juvenile A sexually immature, sexually developing fish. Period extends until the fish begins gametogenesis and enters its fi

ing this period, the juvenile pallid will begin to feed on fish. It m750 mm FL. Within this stage, a Sub-Adult stage may be define

ly from the time fish is a major prey item in the pallid diet and g

Adult A fish capable of spawning during the spawning season (when gametes are mature and environmental conditions are correct). This stage extends from the time the fish enters its first reproductiv

Pre-spawning adult A fish in the final stages of preparing for spawning. Oocytes are grey to black; testis is sinuous containing distinct lobe

germinal vesicle in oocytes is advancing to animal pole but oocyfertilized, and will not resume meiosis when progesterone assay 

Spawning adult A female fish with oocytes that can be fertilized and male fish with flowing milt. Gonads are at stage 5. Oocytes are black. Germinal vesicle is at the 

resume meiosis in the progesterone assay, and oocytes are capab

Post-spawning adult A fish that has finished releasing its gametes. Gonads are flaccid, may be slightly bloody, clear, and barely visibl

will be at their lowest levels. Recrudescent adult A fish with gonads/gametes in a regrowth phase, preparing for the next spawning. Gonads are at stage 2 to 4. The reproductive cycle periodicity for h

two to four years and river-dwelling males one to four years (Alduration of this period is likely food-dependent.
The Pallid Sturgeon 5

Base from U.S. Geological Survey digital data, 1999, 1:2,000,000

Universal Transverse Mercator projection

Zone 15

INTAKE DAM

OAHE DAM BIG BEND DAM

GARRISON DAM

FORT PECK DAM

MELVIN PRICE

LOCK AND DAM

MELVIN PRICE

LOCK AND DAM

FORT RANDALL DAM GAVINS POINT DAM

EXPLANATION

Contemporary range of pallid sturgeon

EXPLANATION

Historical range of pallid sturgeon

Mississippi River

Basin

0 125 250 500 MILES

0 250 500 125 KILOMETERS

Historical and contemporary range defined by

U.S. Fish and Wildlife Service, 2008

Mississippi River

Basin

110° 100° 90°

50°

40°

30°

110° 100° 90°

50°

40°

30°

MT

MN MI

IA IL

ND

SD

NE

WY

ID

UT

AZ

CO

KS

OK

MO

AR

LA

AL

TN

KY

NM TX

MT

MN MI

IA IL

ND

SD

NE

WY

ID

UT

AZ

CO

KS

OK

MO

AR

LA

AL

TN

KY

NM TX

CANADA CANADA

Figure 1. Historical and contemporary range of the pallid sturgeon.

in length. Hybrids between species may be phenotypically 

intermediate or may more closely resemble one parent species 

(Kuhajda and others, 2007).

Both species share common morphological adaptations 

to a benthic life in flowing water (for example, broad flattened 

rostrums, wide pectoral fins, more dorso-ventrally compressed 

body forms, and a long, slender heavily armored caudal 

peduncle). These shared adaptations result in strikingly similar 

appearance between the closely related species. Despite their 

substantial commonalities, pallid sturgeon and shovelnose 

sturgeon each possess dissimilar biological and ecological 

traits that determine differences in distribution and habitat use, 

predict population response in the presence of exploitation 

and environmental alteration, and ultimately explain disparities among the conservation status of the co-occurring species 

(Wildhaber and others, 2007a, 2011a).

The pallid sturgeon lives longer, matures later, and 

attains a larger maximum size than the shovelnose sturgeon 

throughout its range (Mayden and Kuhajda, 1997; U.S. Fish 

and Wildlife Service, 2007; Wildhaber and others, 2007a). 

Where it occurs, the pallid sturgeon is restricted predominately 

to the swifter waters of large, turbid sand-bedded rivers and 

the lower portions of their tributaries where a substantial portion of its diet is native cyprinids and other fish. In contrast, 

the shovelnose sturgeon matures earlier and at a smaller size, 

and feeds nearly exclusively on invertebrates. The shovelnose 

sturgeon commonly uses a wider range of substrates, in large 

main-stem rivers and in smaller, clearer tributaries throughout 

a broader geographic range. Not only does the combination of 

these interspecific differences make the pallid sturgeon more 

vulnerable to exploitation, habitat fragmentation alteration, 

and changes in community composition, these characteristics 

slow population responses to management actions and result 

in a tendency for the species to be resistant to recovery at very 

low densities (Bajer and Wildhaber, 2007; Wildhaber and others, 2007a, 2011a).
6 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Red River

Milk River

Missouri River

Marias

River

Missouri R iver

Big

Horn River

Yellowstone Ri v er

Tongue River

Powder River

Niobrara River

James River

Platte River

Big Sioux

Riv er

Mississippi River

Illinois River

Osage River

Ohio River

Atchafalaya

River

Grand River

Kansas River

Arkansas Riv er

Map area

Management unit

Great Plains

Central Lowlands

Interior Highlands

Coastal Plains 

EXPLANATION

GULF OF MEXICO

Management units defined by

U.S. Fish and Wildlife Service, 2008

Base from U.S. Geological digital data, 1999, 1:2,000,000

Lambert Conformal Conic projection

50°

110° 100° 90°

40°

30°

0

0 100 200 400 KILOMETERS

100 200 400 MILES

MT

MN MI

IL

IA

ND

SD

NE

WY

UT

CO KS

OK

MO

AR

LA

AL

TN

KY

NM TX

CANADA

Figure 2. Pallid Sturgeon Recovery Management Units, Mississippi River drainage.
The Pallid Sturgeon 7

Geographic Range and Historic Abundance

The pallid sturgeon is endemic to the turbid Missouri 

and Mississippi Rivers and the lower parts of larger tributaries (fig. 1). The described species range includes the Lower 

Yellowstone and Missouri Rivers downstream to the confluence with the Mississippi River, and the Mississippi River 

from Keokuk, Iowa (not shown) downstream to the Gulf of 

Mexico, including the Atchafalaya River. Pallid sturgeon have 

been documented in the lower parts of Missouri River tributaries, including the Milk River in Montana, Niobrara and Platte 

Rivers in Nebraska, Big Sioux River in Iowa, Kansas River in 

Kansas, and the Grand and Osage Rivers in Missouri (fig. 3). 

Species occurrence is coincident with turbid, flowing water and 

predominately sand substrate. Patterns of decline indicate that, 

like other Scaphirhynchus species, the pallid sturgeon cannot 

complete its life cycle within reservoirs or without significant 

reaches of free-flowing river (Braaten and others, 2012a). 

Despite a described range exceeding 3,500 miles of river, no 

part is without substantial alteration from dams or barriers to 

passage, impoundment, altered flows, or channelization and 

bank stabilization (U.S. Fish and Wildlife Service, 1993).

Anecdotal references to commercial catches early in the 

twentieth century suggest that pallid sturgeon were more common in highly turbid waters of the Missouri and Mississippi 

Rivers. Ratios of shovelnose to pallid sturgeon in the commercial catch in the Lower Missouri River near West Alton, 

Missouri (not shown) at times may have approached 5 to 1, 

whereas shovelnose are reported to have outnumbered pallid 

sturgeon by 500 to 1 (Forbes and Richardson, 1905) or 300 

to 1 (Forbes and Richardson, 1909) in the less turbid Middle 

Mississippi River upstream from the confluence with the Missouri River. Observations by Bailey and Cross (1954) from 

various locations along the Missouri and Lower Mississippi 

Rivers support a generalized historic pattern of distribution for 

the pallid sturgeon restricted to sandy-bottomed, turbid, flowing water.

Early descriptions of the species suggest that it was not 

common within its range (Forbes and Richardson, 1905; Bailey and Cross, 1954). However, the veracity of this assertion is 

difficult to assess. Early commercial records from the period 

did not discriminate among species of sturgeon and captures 

of pallid sturgeon likely were rare except when fishermen 

specifically targeted sturgeon for flesh or roe. Because pallid 

INTAKE DAM

Mississippi River

Missouri River

Platte River

GARRISON DAM

FORT RANDALL DAM GAVINS POINT DAM

OAHE DAM BIG BEND 

DAM

GARRISON DAM

FORT PECK DAM

FORT RANDALL DAM GAVINS POINT DAM

MELVIN PRICE

LOCK AND DAM

Upper 

Missouri River 

segment

Lower segment of 

Lower Missouri River

Yellowstone 

segment

Upper segment of 

Lower Missouri River 

Lower segment of 

Lower Missouri River

110° 100° 90°

45°

40°

35°

Base from U.S. Geological Survey digital data, 2002, 1:2,000,000

Albers Equal-Area Conic projection

Yellowstone River

0 100 200 400 MILES

0 100 200 400 KILOMETERS

Missouri River

Basin

Figure 3. Missouri River Basin and major tributary rivers with the Comprehensive Sturgeon Research Project study areas.
8 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

sturgeon frequent deep, swift turbid waters they are more difficult to sample compared to shovelnose sturgeon and other 

native species, and it would not be unusual for early biological 

surveys to overlook the species (Funk and Robinson, 1974; 

Kallemeyn, 1983). By the early twentieth century the more 

common, sympatric shovelnose sturgeon had undergone widespread decline and reduction in range (Bailey and Cross, 1954; 

Becker, 1983). Overexploitation and habitat alteration likely 

impacted pallid sturgeon populations as well, far in advance of 

any systematic investigations of species distribution or abundance that could occur. The general paucity of information 

on historic densities or patterns of distribution throughout the 

species’ range has limited the ability to understand the species’ 

needs, document species’ declines, and articulate recovery 

objectives and goals (Kallemeyn, 1983).

Reasons for Decline and Listing

Commercial harvest of sturgeon had diminished most 

North American sturgeon species before the turn of the twentieth century. Overexploitation was predominately responsible for the near extirpation of the lake sturgeon (Acipenser 

fulvescens) from the Missouri and Lower Mississippi Rivers 

in the first decades of the twentieth century; a scant few years 

after the pallid sturgeon was described (Carlson and Pflieger, 

1981). Early dam construction, water withdrawals, and channelization had already resulted in population fragmentation 

(fig. 1), disrupted spawning migrations, and diminished habitat 

availability, and were associated with population declines and 

extirpation of native sturgeon from the Mississippi, Ohio, Illinois, Tennessee, and Rio Grande Rivers (not shown) (Bailey, 

1954; Becker, 1983), and on many of their tributaries well 

before the initiation of main-stem dam construction and bank 

stabilization on the Missouri River.

As the sturgeon fishery began to decline in the Mississippi River Basin, intensive engineering and management of 

the Missouri River for the purposes of navigation, flood control and hydroelectric power substantially altered the riverine 

habitat of the pallid sturgeon. Increasing urban, agricultural, 

and industrial pollution throughout the last century likely 

exacerbated the continuing decline of sturgeon populations 

(U.S. Fish and Wildlife Service, 1993). Surveys by management agencies following the closure of the six main-stem 

dams in the Missouri River collected few sturgeon individuals (Schmulbach and others, 1975; Carlson and others, 1985). 

Low numbers of mature pallid sturgeon in surveys and the 

documented occurrence of hybridization with the closely 

related shovelnose sturgeon (Carlson and others, 1985) 

indicated that populations were below levels considered to 

be self-sustaining. The USFWS formally listed the species as 

Endangered in 1990 in accordance with the provisions of the 

Endangered Species Act of 1973, as amended (U.S. Fish and 

Wildlife Service, 1993). A species recovery plan was developed and released in 1993 (U.S. Fish and Wildlife Service, 

1993), and a 5-year review of the species status was published 

in 2007 (U.S. Fish and Wildlife Service, 2007). A revised 

recovery plan was released in 2014 (U.S. Fish and Wildlife 

Service, 2014). In 2010 the shovelnose sturgeon was listed 

as a threatened species under the Endangered Species Act by 

the U.S. Fish and Wildlife Service because of its similarity 

of appearance to the endangered pallid sturgeon. Threatened 

status mostly eliminated commercial harvest for shovelnose 

sturgeon in the Missouri River and Middle and Lower Mississippi River to prevent incidental or intentional harvest of 

pallid sturgeon in areas where both species co-occur.

Current Population Status

The first estimates of pallid sturgeon abundance were 

summarized by Duffy and others (1996). Estimates from 

various sources and unpublished studies suggested that as 

few as 6,000 or as many as 21,000 wild pallid sturgeon may 

have existed throughout the range of the species at that time. 

Currently, the most precise estimates are from intensively 

studied small, isolated populations of large adults above 

Gavins Point Dam where evidence of natural recruitment has 

been absent for decades. Recent estimates based on markrecapture data for the largest of these populations between 

Fort Peck and Garrison Dams were reported by Braaten 

and others (2009). As few as 158 adults remain (95 percent 

confidence interval [CI] equals 129–193) in the longest 

free-flowing stretch of river between Missouri River mainstem reservoirs. Other reaches above main-stem Missouri 

River reservoirs likely hold a scattered few wild specimens. 

Populations upstream from Fort Peck Dam and between Fort 

Peck Dam and Garrison Dam are currently (2015) being augmented by progeny from the Pallid Sturgeon Conservation 

Augmentation Program (PSCAP) to forestall extirpation and 

conserve species diversity (U.S. Fish and Wildlife Service, 

2008; Heist and others, 2013). Representative progeny from 

nearly all wild adults produced in the hatchery are held as 

potential broodstock at Gavins Point National Fish Hatchery, 

South Dakota (not shown) to serve as potential future broodstock and guard against unexpected catastrophic population 

events.

No reliable pallid sturgeon population size estimates 

yet exist for the entire Lower Missouri River (Wildhaber and 

others, 2015), but evidence indicates that populations are 

reproducing and recruiting, albeit at low levels (DeLonay and 

others, 2009). Using mark-recapture data for a pallid sturgeon 

population within an 80.5-km reach of the Lower Missouri 

River, an estimated 5.4 to 8.9 wild fish/km were present 

annually during 2008–2010, along with 28.6 to 32.3 hatchery fish/km (Steffensen and others, 2012). The wide range of 

early estimates in the Lower Missouri River may, in part, be 

explained by differences in capture probability, low numbers 

of recaptures, poor tag retention, uneven stocking practices, 

and the vagaries of sturgeon migration and emigration. Given 

the variation and limited spatial extent of early estimates, it 

is not possible to extrapolate existing local population size 
Missouri River Management Context 9

estimates across the entire Lower Missouri River. Wildhaber 

and others (2014) did analyze available catch-per-unit-effort 

monitoring data for the entire Missouri River to examine population trends and found no evidence of an increase in relative 

abundance of pallid sturgeon in the Lower Missouri despite 

intermittent stocking efforts from the PSCAP (U.S. Fish and 

Wildlife Service, 2008).

Uncertainty surrounding population size and density 

estimates increases downstream in the Mississippi River. 

The scale of the Middle and Lower Mississippi River poses 

substantial challenges to sampling sturgeon and sustaining 

sufficient effort to conduct effective mark-recapture studies. 

The absence of barriers or boundaries to migration or immigration between the Missouri and Mississippi Rivers, or from 

the confluence of both rivers to the Gulf of Mexico challenges 

population estimate assumptions for a large, mobile riverine 

species. Several studies have examined pallid sturgeon populations in the Middle and Lower Missouri River using catchper-unit-effort statistics or comparative catch ratios with the 

more abundant shovelnose sturgeon (Killgore and others, 

2007a; Killgore and others, 2007b; Garvey and others, 2009). 

These studies suggest that multiple year classes of pallid sturgeon are present and that recruitment is likely occurring. The 

prevalence of hybridization (Tranah and others, 2004) and the 

absence of verifiable field identification metrics to distinguish among pallid sturgeon, shovelnose sturgeon, and pallid 

x shovelnose sturgeon hybrids (Kuhajda and others, 2007) 

constrains the interpretation of abundance estimates.

Population Structure

Genetic studies have indicated rangewide genetic structuring of the pallid sturgeon population (Campton and others, 

2000; Tranah and others, 2001; Schrey, 2007; Schrey and 

Heist, 2007). Genetic differentiation of pallid sturgeon initially 

was observed at the extremes of the species’ geographic range 

(Campton and others, 2000; Tranah and others, 2001). Schrey 

and Heist subsequently detected significant genetic differentiation within the range of the pallid sturgeon; and, further, 

identified three genetic groups (Schrey and Heist, 2007). One 

group is characteristic in the Upper Missouri River Basin in 

Montana and North Dakota, another group is prominent in 

the Middle Mississippi and Atchafalaya Rivers and a third 

genetically intermediate group is prominent in the Lower Missouri River, downstream from the Gavins Point Dam (Schrey 

and Heist, 2007). The Upper Missouri River group was most 

distinct, and less genetic differentiation was observed between 

the Lower Missouri River and the Middle Mississippi and 

Atchafalaya Rivers (Schrey and Heist, 2007). These data indicate that genetic structuring of pallid sturgeon populations is 

natural and predates anthropogenic migratory barriers (Schrey, 

2007; Schrey and Heist, 2007), suggesting that reproductive 

isolation mechanisms were established before construction of 

the dams on the Missouri River.

Recovery Strategy

Substantial progress has been made in understanding the 

biology and ecological requirements of pallid sturgeon since it 

was initially listed and provided protection under the Endangered Species Act in 1990 (U.S. Fish and Wildlife Service, 

2007). Advances in knowledge of pallid sturgeon were summarized in the 5–year status review (U.S. Fish and Wildlife Service, 2007) and incorporated into the revised pallid 

sturgeon recovery plan (U.S. Fish and Wildlife Service, 2014). 

In the revised plan, the USFWS modified the organization 

and implementation of recovery strategies to better align with 

observed genetic population structure and the changing array 

of threats to the species across the breadth of its geographical 

range. The six Recovery Priority Management Areas (RPMA) 

once emphasized by the Recovery Program were revised to 

Recovery Management Units that loosely corresponded to 

physiographic regions (fig. 2), incorporating the potential 

for genetically structured populations on the landscape and 

varying management potential for implementation of recovery 

actions along the length of the species range (U.S. Fish and 

Wildlife Service, 2007).

The species range is divided into the Great Plains 

(GPMU), Central Lowlands (CLMU), Interior Highlands 

(IHMU), and Coastal Plains Management Units (CPMU). 

Though many gaps in species understanding and science needs 

are common among management units, recovery implementation strategies are tailored within geographic units to address 

the specific threats limiting populations (U.S. Fish and Wildlife Service, 2007).

Missouri River Management Context

The pallid sturgeon has declined in a large river system that has been substantially altered to support social and 

economic goods and services. The geography of the Missouri 

River system, its tributaries, and the Mississippi River system 

downstream present important context because the natural 

biophysical capacity of the river system is highly variable, the 

river is naturally very different in different places, and engineering alterations vary markedly along the river. Although 

this species has the potential to migrate hundreds of km 

during a reproductive cycle, there is evidence that indicates 

that genetically defined subpopulations occupied lengths of 

the river with distinctly different combinations of hydrology, 

physiography, water quality, and channel morphology.

Geography

Studies in the CSRP focus on the Missouri River main 

stem and larger tributaries (fig. 3). The Missouri River Basin is 

nearly 1.4 million square kilometers (km2) in area and occupies parts of 10 states and a small part of Canada (fig. 1). It 

extends 24 degrees of longitude east to west and 13 degrees 
10 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

of latitude north to south. The highest elevations are in the 

continental divide in the Rocky Mountains of Montana 

(4,282 meters [m]) and the lowest elevation (124 m) is at the 

confluence with the Mississippi River near St. Louis, Missouri 

(not shown).

The geology of the Missouri River Basin is dominated 

by folded and faulted metamorphic and sedimentary rocks of 

the Rocky Mountains on the western divide, late Mesozoic 

and Tertiary sedimentary rocks created from sediments shed 

from the Rocky Mountains in the Great Plains, and Paleozoic 

marine sedimentary rocks in the Central Lowlands and Ozark 

Plateaus (fig. 4A). Bedrock geology and associated physiographic properties define the broad physiographic provinces 

of the Missouri River Basin (Fenneman and Hohnson, 1946). 

Combined with emerging genetics data, these physiographic 

provinces are presently used to define pallid sturgeon management units for recovery (U.S. Fish and Wildlife Service, 2007, 

2014), and range wide population augmentation (U.S. Fish and 

Wildlife Service, 2008) (fig. 4A), based on the premise that the 

physiographic provinces are reflective of the natural factors 

that contributed to genetic structuring of the pallid sturgeon 

population.

As a species whose evolutionary ancestors can be traced 

back to the late Mesozoic Era (Bemis and Kynard, 1997), 

the lineage of the pallid sturgeon predates the contemporary 

(Quaternary) Missouri River by as much as 150 million years. 

Pliocene and Pleistocene reconstructions of the major river 

drainages of North America indicate that during the last 5 million years the contemporary Missouri River has been assembled from parts of three major river systems (fig. 4B) (Metcalf, 

1966). Disruption and re-assembly of the drainage network 

has been attributed to 7–9 major advances of the continental 

Laurentide ice sheet during the last 2.4 million years (Roy and 

others, 2004; Balco and Rovey, 2010). Although the details 

of timing and locations of the early Pleistocene advances are 

obscure, the overall effect was to deflect formerly north- and 

east-draining rivers to the south (fig. 4B). These dynamics of 

the drainage network during the Pleistocene had the potential 

to mix and isolate populations of Scaphirhynchus sturgeon for 

various time intervals.

Well-preserved late-Pleistocene glacial drift shows that 

the southern glacial boundary interacted with the river in 

multiple locations from Montana to South Dakota resulting in 

direct effects on local habitat that persist today. Interaction of 

the Wisconsinan glaciers with the Missouri River in Montana 

resulted in formation of multiple proglacial lakes. A prominent 

example is glacial Lake Great Falls in Montana (not shown); 

overflow of the lake resulted in occupation of a new channel 

and cutting of Great Falls, which presents a formidable barrier 

to fish passage. Impingement of the ice sheets on the river valley also resulted in local influxes of coarse sediment, for example coarse gravel-cobble deposits that persist near the location 

of Gavins Point Dam at Yankton, South Dakota (Laustrup and 

others, 2007; fig. 3). Downstream from the late-Pleistocene glacial boundary, large quantities of glacial outwash underlie the 

broad alluvial valley of the Lower Missouri River.

Hydrologically, the Missouri River Basin mixes snow 

accumulation and melt processes in the Rocky Mountains and 

Great Plains with less predictable runoff from frontal storms 

and tropical air masses from the Gulf of Mexico (fig. 3). This 

mix of hydroclimatic processes produces a characteristic 

double-peaked annual hydrograph, with March and May–

June flood pulses (Galat and Lipkin, 2000; Pegg and others, 

2003). As the Missouri River flows through the Great Plains, 

it drains a large area with annual precipitation ranging from 

200 to 500 millimeters (mm), a precipitation range generally 

associated with the greatest sediment delivery rates per unit 

watershed area (Langbein and Schumm, 1958). This supply of 

sediment supported dynamic river habitats before channelization and provided the largest fraction of sediment contribution 

to the Mississippi River (Meade, 1995; Jacobson and others, 

2009a).

History of Alteration

The Missouri River has been highly altered from its earliest documented condition in the 18th century. Alteration has 

produced great socioeconomic benefits (U.S. Army Corps of 

Engineers, 2006) but is also considered to be associated with 

substantial stressors on pallid sturgeon populations (Dryer and 

Sandvol, 1993). Agricultural and urban development throughout the basin have substantially altered the landscape, resulting 

in increases in the fluxes of sediment, nutrients, pesticides, and 

other contaminants to streams (Petty and others, 1995; Echols 

and others, 2008; Blevins, 2011; Brown and others, 2011; 

Heimann and others, 2011). The main stem is impounded with 

six large reservoirs that together comprise the largest reservoir 

storage project in North America, with nearly 73 million acre 

feet (MAF) of total capacity (U.S. Army Corps of Engineers, 

2006) (fig. 3). The reservoir system is operated for power 

generation, flood control, public water supply, recreation, and 

to support threatened and endangered species. Operations have 

altered the flow regime variably along the river, and have generally decreased peak flows and increased base flows (Galat 

and Lipkin, 2000) (fig. 5). Reservoir operations at all mainstem dams except Gavins Point involve hydropower loadfollowing discharges resulting in large daily variations. The 

dams also have been effective in retaining sediment, thereby 

substantially decreasing transport of sediment downstream 

(Jacobson and others, 2009a), imposing barriers to upstream 

migration, and, for dams with hypolimnetic releases, decreasing downstream water temperatures (U.S. Fish and Wildlife 

Service, 2000). In addition to the main-stem dams, as many 

as 1,300 additional reservoirs in the basin contribute another 

33 MAF of storage (Galat and others, 2005b).

Downstream from Sioux City, Iowa, the Missouri River 

main stem has been channelized and the banks stabilized 

to support navigation. Channel alterations have resulted in 

reduced channel complexity, a decline in habitat diversity, and 

loss of channel habitat dynamics (Funk and Robinson, 1974; 

Hesse and Sheets, 1993; Jacobson and Galat, 2006) (fig. 6). 
Missouri River Management Context 11

0 200 400 KILOMETERS 100

0 100 200 400 MILES

EXPLANATION

Rocky Mountains, Wyoming Basin 

Central Lowlands

Great Plains

Ozark Plateaus

A

Base from U.S. Geological Survey digital data, 2012

Albers Equal-Area Conic projection

0 200 400 KILOMETERS 100

0 100 200 400 MILES

Limit of pre-Wisconsinan

glaciation

Hypothetical Pliocene

Rivers

Limits of Wisconsinan

glaciation

B EXPLANATION

Great Plains

management unit

Central

Lowlands

management

unit

Interior

Highlands

management

unit

Hudson Bay drainage

Plains 

drainage

Teays-Mahomet 

drainage

110°00’ 100°00’ 90°00’

45°00’

40°00’

110°00’ 100°00’ 90°00’

45°00’

40°00’

Missouri River

Basin b

Missouri River

Basin b

Figure 4. Geographical and geological context of pallid sturgeon recovery implementation. 

A, Physiographic provinces (Fenneman and others, 1946) and Pallid Sturgeon recovery management units, 

Missouri River Basin. B, Hypothetical Pliocene drainage network (Metcalf, 1966), pre-Wisconsinan and 

Wisconsinan glacial limits (Garrity and Soller, 2009), compared to the present-day drainage network.
Base from U.S. Geological Survey digital data, 2012, 1:2,000,000 Albers Equal-Area Conic projection 0 200 400 KILOMETERS 100

0 100 200 400 MILES

Hermann,MissouriKansas City,MissouriSioux City,IowaBismarck,North Dakota

Williston,North Dakota

Wolf Point,Montana

05

10152025303540

Jan. Mar. May July Sept. Nov. 0

102030405060708090

100

0

102030405060708090

100

140120100

80604020

0

0

4080

120160200

0

100200300

Discharge, in thousands of

cubic feet per second

Discharge, in thousands of

cubic feet per second

Discharge, in thousands of

cubic feet per second

Discharge, in thousands of

cubic feet per second

EXPLANATION

Managed flow  regimeNatural flow  regime

EXPLANATION

Managed flow  regimeNatural flow  regime

Jan. Mar. May July Sept. Nov. Jan. Mar. May 

Jan. Mar. May 

Jan. Mar. May 

Jan. Mar. May 

Discharge, in thousands of

cubic feet per second

Discharge, in thousands of

cubic feet per second

110°00’ 100°00’ 90°00’

45°00’

40°00’

Missouri River

Hermann

Williston

Bismarck

Pierre

Kansas City

WolfPoint

Sioux City

Hermann

Williston

Bismarck

Pierre

Kansas City

WolfPoint

Sioux City

Missouri River

Basin b

Figure 5.

Variation in hydrologic alteration along the Missouri River. Duration hydrographs show the 

modeled interquartile range of discharges for each day of the year from 1898 to 1997. Data are from the USACE daily routing model (U.S. Army Corps of Engineers, 1998; unpub. data).
Missouri River Management Context 13

Channelization and snagging (removal of woody debris) projects started as early as steamboat navigation on the Missouri 

River (circa 1819) and continued through completion of the 

Bank Stabilization and Navigation Project (BSNP) in 1981 

(Ferrell, 1996). Channelization, associated land accretion, and 

levees have been estimated to account for loss of 404 km2 of 

aquatic habitat, 274 km2 of sandbars and low-lying lands, and 

1,432 km2 of terrestrial habitat within the riverine meander 

belt (U.S. Army Corps of Engineers, 2002).

The Missouri River main stem also serves as receiving waters for industrial and municipal waste and as cooling 

water for thermal power plants. With cumulative inputs from 

municipalities and agriculture throughout the basin there is 

potential for exposure of pallid sturgeon and other native fauna 

to elevated contaminant loads, including metals, pesticides, 

herbicides, pharmaceuticals, bacteria, and nutrients (Petty and 

others, 1995; Poulton and others, 2003; Echols and others, 

2008; Blevins, 2011).

Missouri River Restoration Programs

Concerns about restoring some aspects of the Missouri 

River ecosystem began as early as the late 1950s with the 

Fish and Wildlife Coordination Act of 1958, which provided 

the USACE with authority to study how to “restore, preserve, 

or otherwise develop (Ferrell, 1996)” land and waters in the 

Missouri River BSNP area. The selected wording of “restore, 

preserve, or develop” is indicative of various definitions and 

perceptions of the restoration concept. Ecological “restoration” is usually defined similar to the following: “Reestablishment of the structure and function of an ecosystem, resulting 

in a dynamic and self-sustaining condition that is as close as 

possible to pre-disturbance conditions (National Research 

Council, 1992).” This definition can be problematic because 

of difficulties in defining and quantifying dynamic pre-disturbance conditions (Marris, 2011). Some restoration ecologists have used broader definitions or different terms, such as 

“rehabilitation”: “Pragmatic recovery of ecosystem structure 

and function, but not necessarily to a pre-disturbance condition (Ormerod, 2003)” or, “putting back into good condition 

or working order (National Research Council, 1992).” A 

complicating factor on the Missouri River is the mixture of 

objectives, which are summarized in the authorizing legislation for the Missouri River Ecosystem Restoration, the 

Water Resources Development Act (WRDA) of 2007 (U.S. 

Congress, 2007) as the following: “(A) to mitigate losses of 

aquatic and terrestrial habitat; (B) to recover federally listed 

species under the Endangered Species Act of 1973 (16 USC 

1531 et seq.); and (C) to restore the ecosystem to prevent 

further declines among other native species.” Importantly, the 

term “recovery” is used specifically in the Endangered Species 

Act to mean: “The process by which the decline of an endangered or threatened species is stopped or reversed, or threats 

to its survival neutralized so that its long-term survival in the 

wild can be ensured, and it can be removed from the list of 

threatened and endangered species.” Thus, recovery is specific 

to a species like the pallid sturgeon, and recovery of a species may happen with or without restoration or rehabilitation 

of its environment or associated native species. In this report 

we use the word “recovery” under this narrow definition. We 

use the definition of “restoration” adopted by the Society for 

Ecological Restoration: “Ecological restoration is the process of assisting the recovery of an ecosystem that has been 

degraded, damaged, or destroyed”. “Mitigation” is used to

rol15-EMSB00-0040 Figure 6

91°28' 91°26' 91°24' 91°22'

38°44'

38°42'

0 0.5 1 2 MILES

0 1 2 0.5 KILOMETERS

Figure 6. Modern (2000) channel overlain on historical (1894) channel map, Lower Missouri River at Hermann, 

Missouri (from Jacobson and Galat, 2006).
14 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

denote an action to change the biophysical condition of a site 

to compensate for natural functions lost elsewhere (Society for 

Ecological Restoration International Science and Policy Working Group, 2004).

The Missouri River Bank Stabilization and Navigation 

Project Fish and Wildlife Mitigation Program (Mitigation 

Program) was authorized in the Water Resources Development Act (WRDA) of 1986, 5 years after completion of the 

BSNP, and amended in the WRDA of 1999 (National Research 

Council, 2002). The Mitigation Program was intended originally to mitigate for habitat losses due to the BSNP, with a 

goal of restoration of 166,750 acres (of channel, sandbar, and 

meander belt habitat, about 32 percent of estimated habitat 

lost (U.S. Army Corps of Engineers, 1981). In 2000, the 

USFWS published a biological opinion finding that USACE 

operations of the Missouri River were likely to jeopardize the 

existence of the pallid sturgeon and two shorebirds, the piping 

plover (Charadrius melodus) and interior least tern (Sternula 

antillarum); the biological opinion defined reasonable and 

prudent actions (RPAs) to avoid jeopardy to these species 

(U.S. Fish and Wildlife Service, 2000). The biological opinion 

was amended by a supplemental biological opinion in 2003 

(U.S. Fish and Wildlife Service, 2003) and RPAs were modified. The RPAs for the pallid sturgeon include implementation 

of adaptive management, monitoring, and research; restoration 

of 20–30 acres per mile of shallow-water habitat; increased 

propagation and augmentation of pallid sturgeon; and flow 

pulses from Fort Peck and Gavins Point Dams. Both the 2003 

biological opinion and the USACE biological assessment 

(U.S. Army Corps of Engineers, 2003) emphasized the importance of robust research, monitoring, and evaluation to support 

adaptive management.

In the WRDA of 2007, the goals for compliance with the 

amended biological opinion and for the Mitigation Program were collected into the Missouri 

River Recovery Program. In addition, the WRDA 

of 2007 formalized the creation of a stakeholders 

group, the Missouri River Recovery Implementation Committee (MRRIC), which is charged with 

providing recommendations and guidance on 

recovery and mitigation activities. The WRDA 

of 2007 also authorized mitigation projects along 

the Missouri River main stem in the upper basin, 

including Montana, North Dakota, Nebraska, and 

South Dakota, and authorized use of USACE 

funding to assist the Bureau of Reclamation with 

planning and construction of fish passage around 

the Lower Yellowstone Intake Diversion Dam 

(Intake Dam). The USACE developed the Missouri River Recovery Program Integrated Science Program (ISP) to understand and enhance 

knowledge of the Missouri River system to 

ensure that management decisions are based on 

the best available science.

The Comprehensive Sturgeon Research 

Project

The Comprehensive Sturgeon Research Project evolved 

from a request from the USACE to the USGS in 2003 to 

develop a research program that would address the basic question “What critical ecological factors contribute to successful 

pallid sturgeon and shovelnose sturgeon reproduction and 

survival in the Missouri River?” The fact that such a basic 

question was asked in 2003 is evidence of the lack of scientific 

understanding available then about the reproductive ecology 

of the pallid sturgeon in the Missouri River. Beginning with 

the first decade of the 21st century the accumulated knowledge 

about pallid sturgeon ecology has grown substantially (fig. 7), 

coincident with the elevation of interest in the Missouri River 

Basin. At the same time, numerous engineering, hydrology, 

geomorphology, sediment transport, and ecology studies 

indirectly related to pallid sturgeon have been pursued on the 

Missouri River. As a result, the knowledge base that exists in 

2012 is much improved from what existed at the turn of the 

21st century.

 The science direction of CSRP has been guided by 

results of sturgeon research workshops convened in 2004 

(Quist and others, 2004) and 2007 (Bergman and others, 

2008), by hypotheses that emerged about the role of a naturalized flow regime in pallid sturgeon reproduction during a 

series of workshops in 2005 (Jacobson and Galat, 2008), by 

feedback from an independent science review (Sustainable 

Ecosystems Institute, 2008), and most recently by perspectives of the MRRIC Independent Science Advisory Panel 

(ISAP) (Doyle and others, 2011). As a result, CSRP research 

objectives have emphasized science information gaps related 

Year

Cumulative number of peer-peviewed

articles and reports

0

100

200

300

400

1970 1980 1990 2000 2010

Figure 7. Cumulative number of peer-reviewed scientific articles and reports 

related to pallid sturgeon biology, ecology, and habitat, 1970–2012
The Comprehensive Sturgeon Research Project 15

to priority management issues, including understanding of 

the role of pulsed flow releases from Gavins Point Dam and 

Fort Peck Dam (fig. 1), and understanding of the functions of 

constructed shallow-water habitat in the sturgeon life cycle. 

The goal of CSRP is to produce credible and salient scientific 

information and to interact with decision makers and stakeholders in a way that establishes the legitimacy and usefulness 

of the information (Cash and others, 2003).

Comprehensive Sturgeon Research Project 

Approach

The Comprehensive Sturgeon Research Project has 

applied an integrated, comprehensive research strategy. Field 

studies in three distinct river sections (Lower Missouri River, 

Yellowstone River, and Upper Missouri River) (fig. 3) provide 

a geographic comparative basis for discriminating physical and 

population controls on reproduction and recruitment. The natural and managed biophysical capacities of these river sections 

are distinctly different and varying fish responses within them 

provide fundamental insights into constraints on population 

growth. Within each of the three river sections our approach 

integrates reproductive behaviors and physiology of adult fish, 

understanding of where and when spawning occurs, validation 

of spawning through larval sampling, detailed assessments of 

migration, spawning, and drift/retention habitats, and integrative larval and young-of-year (YOY) sampling. These field 

studies are essential to place laboratory and theoretical information into the real-world context, and especially to establish 

how management actions may be linked to fish responses. 

Laboratory studies provide control and precise observations, 

whereas the field studies, with less control and precision, 

quantify the behaviors within the actual river environment. 

Information developed through laboratory and field studies also 

provides insights into cause and effect that provide essential 

context to mathematical models of pallid sturgeon populations 

(Bajer and Wildhaber, 2007) and complement population monitoring data being collected by the Pallid Sturgeon Population 

Assessment Project (Drobish, 2008) and the Habitat Assessment Monitoring Project (Schapaugh and others, 2010).

Some of the present (2015) understanding of pallid 

sturgeon biology relies on inference from other, comparative 

sturgeon species. Use of comparative species is typical when 

developing understanding of a very rare fish. When pallid 

sturgeon research on the Missouri River was beginning in 

the 2000s, we began with accepted models for the reproductive strategies of other, well-characterized sturgeon, including 

white sturgeon (Galbreath, 1985; Paragamian, 2012), shortnose 

sturgeon (Bain, 1997; Kynard, 1997; Kynard and others, 2009), 

and shovelnose sturgeon (Moos, 1978). The shovelnose sturgeon in particular has provided useful information, especially 

because documented hybridization between the pallid and 

shovelnose indicates some sharing of reproductive strategies 

(Carlson and others, 1985). Although these species provided 

a starting point for understanding, their informational value 

is now perceived as limited because of differences in known 

behaviors from other species; in the case of the shovelnose 

sturgeon, it has been documented that the juvenile shovelnose 

diet is dominated by insects whereas pallid sturgeon transition 

to a piscivorous diet around age 5–7 years (Gerrity and others, 

2006; Grohs and others, 2009). In this report we differentiate 

between documented pallid sturgeon information and information that might be inferred from other sturgeon species.

Pallid Sturgeon Conceptual Life-Stage Model

Organization of information in this report is based on a 

conceptual model of pallid sturgeon life stages (Wildhaber and 

others, 2007a; Wildhaber and others, 2011a; table 1, fig. 8.) 

The life-stage model serves to organize understanding by 

focusing on populations during life stages, the transition probabilities between life stages, and the conditions and processes 

that affect the transition probabilities. Transitions between 

life stages are conceptual and are not instantaneous. Some 

transitions, such as hatching from embryo to free embryo, are 

rapid, and others, such as the transition from juvenile to adult 

are gradual. Moreover, although life stages can be defined 

conceptually based on a stage of development or function, 

the operational delineation of life stages is more difficult. For 

example, the transition from exogenously feeding larva to 

juvenile is conceptually based on when the fish has developed 

all its rays and fins, but capturing fish in the field is a function 

of size relative to the sampling gear and does not necessarily differentiate between fish on either side of this transition. 

Field assessment of annual reproduction may use gear types 

designed to sample YOY or age-0 individuals. Depending on 

the time of sampling and location within the species range, 

sampling efforts for age-0 sturgeon may include exogenously 

feeding larva and juveniles produced in the same season. 

Hence, we have operational definitions that are intended to 

align as much as possible with the concepts, but are acknowledged to be imperfect (table 1).

The terminology for the life stages used in this report is 

defined in table 1. The life stages coincide with those in the 

conceptual model of the pallid sturgeon life cycle proposed by 

Wildhaber and others (2007a, 2011a; fig. 8). The five principle 

periods in the lifecycle of the pallid sturgeon consist of embryo, 

free embryo, larval, juvenile, and adult stages. These designations are intended to establish a common conceptual framework 

to facilitate communication and for biological study of the various phases in the pallid sturgeon life cycle. The terms embryo, 

free embryo, and larva are adopted from Balon’s terms for the 

early intervals in fish development (Balon, 1984). Embryos are 

developing fish within a protective membrane; free embryos 

have hatched but rely on yolk for nutrition, whereas larvae 

have begun to feed exogenously. A pallid sturgeon larva (and 

Scaphirhynchus sturgeons in general) becomes a juvenile with 

absorption of the last of its pre-anal finfold (Snyder, 2002). 

Juveniles appear as adults morphologically but are sexually 

immature. An adult fish is classically considered a fish capable 
Conditions and processes Conditions and processes Conditions and processes Conditio

proce

Conditions and processes Conditions and processes Conditions and processes Conditions and processes Transition probability Transition probability Transition probability Trans

proba

Transition probability Transition probability Transition probability Transition probability Stocking Stocking 

Broodstock Free embryo Larva 

Pre-spawning adult Post-spawning adult Spawning adult Gametes Embryos Recrudescent adult Upstream Downs

Migrate Migrate Migrate Migrate Overwinter Overwinter Overwinter Overwinter Drift Drift Drift Grow Grow Grow Disperse Disperse Dispe

Spawn and incubate Spawn and incubate Spawn and incubate

Figure 8. Simplified conceptual life-stage model for pallid sturgeon, modified from Wildhaber and others (2007a, 2011a).
Sturgeon Habitat Variability within the Missouri River 17

of spawning and therefore having developed the necessary 

organs and sensory structures to develop gametes and shed 

them if properly cued. We have expanded this definition to 

include pallid sturgeon that are in the process of gametogenesis 

for the first time and therefore entering their first reproductive 

cycle. Although much has been learned in the past decade, 

the normal biology of pallid sturgeon at many of these stages 

remains incompletely described and, as such, the descriptions 

we have provided are based on the best available science at 

this time. Within this set of discrete life stages, substages may 

be operationally defined for a particular study to facilitate 

analyses. This is particularly relevant to understanding and 

identifying limitations to survival and threats preventing transition from one life stage to the next. For example, within the 

free-embryo life stage, the period during which the free embryo 

is transitioning from passive drifting to active drifting may be 

operationally identified and defined as free embryos that have 

reached a specific developmental or behavioral milestone (as 

Cumulative Thermal Units or CTUs). The further splitting of 

the primary life stages in table 1 into substages is described in 

the text of this report where applicable.

Organization of the science by life stage is essential to 

focus on specific linkages between stressors, management 

actions, or restoration actions that can affect specific transitions. In addition, because the pallid sturgeon can migrate for 

10s or 100s of miles in a season, different life stages play out 

in different parts of the river, generally with spawning habitat 

at the apex of reproductive migrations and “settling” habitat 

for the transition from free embryo to exogenously feeding 

larva substantially farther downstream.

Sturgeon Habitat Variability within the 

Missouri River

Variability in hydrology, geomorphology, and water 

quality within the Missouri River Basin defines the template 

for CSRP field-based studies. The design compares sturgeon 

reproductive behavior, recruitment, and growth in distinctly 

different parts of the Missouri River system (fig. 3). The following sections describe the variation in hydrology, sediment 

regime, channel morphology, and water quality along the river 

and how the variability is used to constrain understanding of 

the pallid sturgeon ecology.

Yellowstone River

The Yellowstone River provides a nearly unaltered flow 

regime. The flow of the Upper Missouri River downstream 

from the confluence with the Yellowstone River retains the 

unregulated characteristics of the natural Yellowstone River 

hydrograph to the headwaters of Lake Sakakawea (fig. 9, as 

measured just downstream from its confluence with the Missouri River at Williston, North Dakota) (fig. 5) and channel 

morphology (fig. 10) that is relatively natural and complex. 

The Yellowstone River is the third greatest contributor of 

suspended sediment to the Missouri River main stem system. 

During 1975–1991 the median annual suspended sediment 

load at Sidney, Montana (fig. 9) was 9.2 metric tons (MT) 

(Heimann and others, 2011). Trends in suspended sediment 

concentration were negative indicating diminished 

yield over time; suspended 

sediment concentrations in the 

period after 1967 were 47 percent of historic values before 

1953. Suspended sediment 

concentrations from 1971 to 

2012 at Sidney, Montana had 

a median of 211 milligrams 

per liter (mg/L) and an interquartile range of 15,490 mg/L 

(fig. 11).

The Yellowstone River 

has a steep gradient and 

coarse bed throughout most of 

its course. The Lower Yellowstone River, defined as the 

downstream-most 150 miles, 

flows through the Great Plains 

from where the sediment-rich 

rol15-EMSB00-0040 Delonay Figure 9

106°00' 104°00'

48°00'

47°30'

47°00'

0 30 60 KILOMETERS 15

Base from U.S. Geological Survey digital data, 2012, 1:1,000,000 0 15 30 60 MILES

Universal Transverse Mercator projection, zone 13

Fort Peck Lake

Milk River

Lake

Sakakawea

Yellowstone River

Upper Missouri River

MONTANA

NORTH DAKOTA

Williston Culbertson

Nohly Wolf

Grand Point

Champs

Sidney

Mile 0.5

Glendive

INTAKE 

DAM

Powder River

Redwater River

Poplar River

Mile 2.5

FORT PECK DAM

48°30'

River mile marker

EXPLANATION

Figure 9. Location of Upper 

Missouri River and Yellowstone 

River study sections.
18 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

0 0.5 1 2 KILOMETERS

0 0.5 1 2 MILES

47°20'

47°22'

47°24'

104°26' 104°24' 104°22'

Digital imagery from U.S. Department of Agriculture National Aerial Imagery Program

Albers Equal-Area Conic projection

rol15-EMSB00-0040 Figure 10 Figure 10. Representative channel morphology in the Yellowstone study section.
Sturgeon Habitat Variability within the Missouri River 19

Powder River enters the Yellowstone River at river mile 

(RM) 148 to its confluence with the Missouri River (Applied 

Geomorphology Inc., 2004). The Lower Yellowstone River’s 

channel form ranges from reaches with a single-threaded 

channel to anabranching and braided reaches with frequent 

islands, chutes, backwater areas, and mid-channel bars (Koch 

and others, 1977). Total width of the river channel corridor 

(including islands) varies from 130 to 3,000 meters (m), and 

channel width (including side channels but not vegetated 

islands) varies from 130 to 1,090 m. A highly braided section 

of the Lower Yellowstone River with frequent side channels 

extends from RM 104 to 38 and is roughly centered on Intake, 

Montana, at RM 73 (fig. 12). Downstream from this braided 

section, the Yellowstone River is primarily a single-threaded 

channel with numerous gravel bars until its confluence with 

the Missouri River. The Lower Yellowstone River is in frequent contact with bedrock bluffs of highly erodible shale rock 

and glacial outwash terraces, which are the source of much of 

the gravel in the river (Zelt and others, 1999; Applied Geomorphology Inc, 2004) (fig. 12). The river has a mixed bed of 

fine and gravel-to-cobble substrates with occasional bedrock 

outcrops in the channel.

The natural capacity of the Yellowstone River to support 

pallid sturgeon populations has been altered by two factors. 

Intake Dam at Intake, Montana (fig. 9), is 70 RM upstream 

from the Yellowstone and Missouri Rivers confluence and 

likely presents a limit to upstream passage of sturgeon as only 

one pallid sturgeon has been captured upstream from the dam 

(Watson and Stewart, 1991), and multiple pallid sturgeon 

migrations have been documented as far as Intake Dam with 

no evidence of passage (Fuller and others, 2008; DeLonay and 

others, 2014). Survival of drifting free embryos of fish that 

spawn in the Yellowstone River downstream from Intake Dam 

is likely limited downstream by the upper reaches of Lake 

Sakakawea, about 19 miles downstream from the confluence 

of the Yellowstone and Upper Missouri Rivers. It has been 

hypothesized that conditions in reservoirs are not suitable for 

survival of free embryos (Kynard and others, 2007; Braaten 

and others, 2012a). The resultant limited length of free-flowing river for free-embryo dispersal and development is the 

predominant hypothesis for the lack of recruitment in the Yellowstone and Upper Missouri Rivers (U.S. Fish and Wildlife 

Service, 2000).

Water quality in the Yellowstone River is generally good 

and not considered to be a limiting factor for most river biota. 

In the Yellowstone Basin National Water Quality Assessment 

Program report (Miller and others, 2005), concentrations 

of coliform bacteria were generally low and fecal coliform 

bacteria samples exceeded the U.S. Environmental Protection Agency (EPA) recommended limits in only 2.6 percent of 

samples. Nutrient concentrations were generally low although 

median total phosphorous concentrations exceeded the EPA 

goals for preventing nuisance plant growth in some samples. 

Concentrations of pesticides were also low and all below 

aquatic-life or human-health criteria. Measured turbidity 

recorded from 2002 to 2009 in the Yellowstone River near 

mile 0.8 had a median of 152 nephelometric turbidity units 

(NTU) and an interquartile range of 336 NTU (fig. 13).

Suspended-sediment concentration, 

in milligrams per liter

1

10

100

1,000

10,000

100,000

Yellowstone River at

Sidney, Montana

Missouri River at

Culbertson, Montana

n = 833,

1971–2012

n = 213,

1971–2007

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 10th percentile

Individual observation above 90th percentile

90th percentile

75th percentile

Figure 11. Suspended sediment 

concentrations, Yellowstone River at 

Sidney, Montana, and Missouri River at 

Culbertson, Montana.
20 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Minimal published information exists on contaminant 

levels as related to pallid sturgeon ecology in the Yellowstone 

River. In one study from the late 1980s, a pallid sturgeon 

captured near the Yellowstone–Missouri River confluence 

was reported to have elevated levels of DDT and its metabolites, polychlorinated biphenyls (PCBs), chlordane, mercury, 

selenium, and cadmium (Ruelle and Keenlyne, 1993). In particular, this fish had PCB concentrations in its liver and flesh 

that were about 10 times the Federal Food and Drug Administration action level of 2.0 milligrams per kilogram (mg/kg) 

(Blevins, 2011). For long-lived fish like the pallid sturgeon, it 

would not be unusual to document the accumulation of persistent contaminants in older individuals. Information is lacking 

to determine whether contaminants are an important issue for 

sturgeon populations.

Annual water temperature regimes are considered to be 

stable in the Yellowstone River because of the lack of development in the basin (Miller and others, 2005). Historical datasets 

are generally lacking. Recent median temperature measured 

near RM 2.5 during late-May to October each year from 2002 

to 2012 was 20.0 °C, with an interquartile range of 6.1 °C 

(fig. 14). Temperatures are highly seasonal (fig. 15).

rol15-EMSB00-0040 Figure 13

rol15-EMSB00-0040 Delonay Figure 12 Island and channel width, in meters

0

1,000

2,000

3,000

Channel width,

in meters

0

250

500

750

1,000

Number of channels

2

4

6

Valley width

and distance

to valley wall,

in kilometers

0

2

4

6

8

10

Intake

structure

Missouri

River

Powder

River

Distance on Yellowstone River upstream from the Missouri River

140 120 100 80 60 40 20 0

Date of pallid

sturgeon 

relocation

1/1/2011

1/1/2012

1/1/2013

Channel width

EXPLANATION

Channel width including islands 

Valley width

Distance to left 

valley wall 

Distance to right 

valley wall 

Pallid sturgeon telemetry location 

Pallid sturgeon migration pathway 

habitat measurement location

Pallid sturgeon spawning site

Side channel location 

Channel morphology data and valley width 

from Applied Geomorphology (2004)

Figure 12. Channel and island width, number of channels, valley width, pallid sturgeon relocations and habitat 

data collection locations on the Lower Yellowstone River from the Powder River to the Missouri River, Montana 

and North Dakota.
Sturgeon Habitat Variability within the Missouri River 21

rol15-EMSB00-0040 Delonay Figure 13 Turbidity, in nephelometric turbidity units

0

200

400

600

800

1,000

1,200

Yellowstone River near

river mile 0.5

Missouri River near

Nohly, Montana,

 river mile 1,590

n = 803, 2002–09 n = 2,193, 2002–09

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 10th percentile

Individual observation above 90th percentile

90th percentile

75th percentile

Figure 13. Turbidity distributions, Yellowstone River near mile 0.5 and Missouri River near Nohly, Montana, near mile 1,590. 

Note that the instruments were only capable of reading to 1,000 NTU, so the distributions are truncated above that value. 

Data from Fuller and Braaten (2012).

rol15-EMSB00-0040 Delonay Figure 14

Water temperature, in degrees Celsius

0

5

10

15

20

25

30

35

Yellowstone River near

river mile 0.5

Missouri River near

Nohly, Montana, 

river mile 1,590

Missouri River near

Grand Champs, Montana, 

river mile 1,745

n = 1,719 n = 1,719 n = 1,719

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 10th percentile

Individual observation above 90th percentile

90th percentile

75th percentile

Figure 14. Temperatures from 2001 to 2012, Upper Missouri River and Yellowstone River. Records run from May 21 through October 

11 of each year.
22 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Upper Missouri River

The Upper Missouri River (used in this report to refer 

to the river from upper reaches of Lake Sakakawea to Fort 

Peck Dam) has a near-natural channel morphology with few 

instances of bank stabilization or other river training structures 

(fig. 16). However, because it is downstream from a large 

reservoir this segment of river has a highly altered flow regime 

(fig. 5). Recent calculations of sediment load are not available for the Upper Missouri River, but suspended sediment 

concentrations at Culbertson, Montana 1971–2007 report a 

median of 237 mg/L and an interquartile range of 2,351 mg/L. 

The median is very similar to that on the Yellowstone River 

although the interquartile range of concentrations on the Yellowstone is much greater (fig. 11). High suspended sediment 

concentrations at Culbertson indicate the additions of suspended sediment from the Milk, Poplar, and Redwater Rivers 

(fig. 9).

Channel morphology data are less available on the Upper 

Missouri River compared to the Yellowstone and Lower Missouri Rivers. The planform of the river is relatively complex 

and natural (fig. 16), and lack of sediment has resulted in 

channel incision since Fort Peck Lake (fig. 9) was completed. 

However, incision near the dam seems to have equilibrated 

since the 1960s (Williams and Wolman, 1984; U.S. Army 

Corps of Engineers, 2012). The Upper Missouri River also 

offers the opportunity to evaluate sturgeon selection of tributaries, notably the Poplar, Redwater, and Milk Rivers. Among 

these, the Milk River watershed is substantially the largest at 

17,670 square miles and is a potential contributor of warmer 

water and increased turbidity relative to that available in the 

Upper Missouri River main stem.

Modeled and measured nutrient loads in the Upper 

Missouri River downstream from Fort Peck Dam are low, 

indicative of low inputs of nitrogen and phosphorous and 

the attenuating effects of Fort Peck Lake (Brown and others, 

2011). Dams and reservoirs in the Upper Missouri River have 

been associated with as much as 60 percent attenuation of 

nitrogen and 72 percent of the phosphorous loads, with most 

of the attenuation being explained by Fort Peck Lake (Brown 

and others, 2011). Similar to suspended sediment concentrations, median turbidity in the Upper Missouri River is similar 

to the Yellowstone River but is less variable (fig. 13).

Water temperatures in this river segment are affected by 

the hypolimnetic releases from Fort Peck Dam, and generally increase in the downstream direction with atmospheric 

warming and tributary inputs. The effect of reservoir releases 

on water temperature can be seen by examining the relation 

between air temperature, water temperature, and discharge at 

the Wolf Point, Montana (fig. 9) streamgage. Residuals from a 

regression between air and water temperature, plotted against 

discharge, show a negative trend, indicating decreasing water 

Day of year

Temperature, in degrees Celsius

6

8

10

12

14

16

18

20

22

24

26

28

June 1 July 1 August 1 September 1 October 1

EXPLANATION

Yellowstone River near river mile 2.5

Upper Missouri River near Nohly, Montana (river mile 1,590)

Upper Missouri River near Grand Champs, Montana (river mile 1,745)

rol15-EMSB00-0040 Delonay Figure 15

Figure 15. Interquartile ranges of water temperatures by day of year on the Yellowstone and Upper 

Missouri River from daily means, 2001–2012.
rol15-EMSB00-0040 Figure 16

105°36' 105°34' 105°32' 105°30'

48°06'48°04'

Digital imagery from U.S. Department of Agriculture National Aerial Imagery Program, 2011

Albers Equal-Area Conic projection

0 10.5 2 KILOMETERS

0 0.5 1 

Figure 16. Representative channel morphology in the Upper Missouri River study section.
24 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

temperature with increasing discharge from the dam (fig. 17). 

The warming trend downstream is evident comparing two 

sites on the Upper Missouri River. At Grand Champs, Montana (fig. 9), the temperature monitoring station closest to the 

dam, the median seasonal (May 20–October 1) water temperature from 2001 to 2012 was 14.7 o

C (interquartile range, 

13.2–16.0) whereas downstream at Nohly, Montana, median 

water temperature was 18.5 oC (interquartile range 15.3–21.0) 

(fig. 14). Temperature depression downstream from the dam 

persists during spring-fall season. At Nohly the seasonal temperature distribution of the Upper Missouri River more closely 

matches the Yellowstone River, although Upper Missouri 

River water temperatures are noticeably colder mid-July–midSeptember (fig. 15).

Lower Missouri River

The upstream study section of the Lower Missouri River 

has a highly altered flow regime (fig. 5) because of its position directly downstream from the main-stem reservoir system 

(fig. 18). Being close to the dam, this section presents options 

for experimental flow releases, which have been used to evaluate effects of pulsed flows on pallid sturgeon reproduction 

(Jacobson and Galat, 2008; Doyle and others, 2011). The flow 

regime regains seasonal variability in the downstream direction, although at Hermann, Missouri, RM 100, lowered spring 

peaks and increased late-summer/fall flows are still distinguishable (fig. 5).

The suspended sediment load is near zero at the dam 

and increases downstream to 6–10 MT/year (y) at Sioux City, 

Iowa; annual loads vary among published sources based on the 

years for which loads are calculated and averaged (Jacobson 

and others, 2009a; Heimann and others, 2011). Notably, modern suspended sediment loads are about a tenth of the earliest 

measured, pre-dam loads at Sioux City (64 MT/y; Jacobson 

and others, 2009). Post-dam sediment loads increase downstream throughout the upstream section to 16.4–18.9 MT/y at 

Omaha, 27.6–77.6 MT/y at St. Joseph, and 55.2–77.0 MT/y at 

Hermann (Jacobson and others, 2009a).

As a result of the lack of sediment from the dam, the 

channel has incised and water-surface elevations have 

decreased as much as 3.8 m since the dams were closed 

(U.S. Army Corps of Engineers, 2012). Decreases in stage and 

mean streambed elevation have been documented downstream 

to Omaha (Jacobson and others, 2009a). Stages at low flows 

have been stable for the last 10 years at Sioux City, Iowa, 

and Omaha, Nebraska, with the exception of steep decreases 

measured after the 2011 flood (U.S. Army Corps of Engineers, 

2012). From Omaha to St. Joseph, Missouri, stage trends for 

low flows have been stable to slightly declining, whereas 

stage trends for flows 70,000–100,000 cubic feet per second 

(ft3/s) (5–10 percent flow exceedance) have been increasing, presumably because of loss of channel capacity due to 

sedimentation in overbank areas adjacent to the channel. 

From St. Joseph to Kansas City, Missouri, low-flow stages 

decrease markedly, a result considered to be associated with 

Air temperature, in degrees Celsius

0 5 10 15 20 25 30 35

Water temperature, in degrees Celsius

0

5

10

15

20

25

30

35

Discharge, in cubic feet per second

2,000 4,000 6,000 8,000 10,000 12,000

Residual from linear regression

-10

-5

0

5

10

WaterTemp=6.1+0.5×AirTemp

r 2

=0.71

Residual=3.3-0.0004×Discharge

r 2

=0.103

A B

p<0.0001 p<0.0001

Figure 17. Relation between air and water temperature near Fort Peck, Montana and Wolf Point, Montana, 63 river miles downstream. 

A, Least-squares linear regression between air temperature and water temperature (p<0.0001). B, Least-squares linear regression 

between residuals (actual minus predicted) of the air temperature and water temperature regression and discharge. The residual plot 

shows that water temperature is significantly correlated with discharge, accounting for air temperature (p<0.0001).
Sturgeon Habitat Variability within the Missouri River 25

a combination of commercial sand and gravel mining from 

the river and channelization. Downstream from Kansas City, 

low-flow stage trends recover and then are stable to slightly 

decreasing, whereas high-flow stages increase presumably due 

to the effects of levees constricting overbank flows (Pinter and 

Heine, 2005; Pinter and others, 2010).

Channel morphology in the Lower Missouri River varies geographically with the degree of channel engineering, 

geologic setting, and with downstream increases in discharge 

and sediment inputs from tributaries (Reuter and others, 2008; 

DeLonay and others, 2009; Elliott and others, 2009; Jacobson and others, 2009b; Reuter and others, 2009; DeLonay 

and others, 2010; Bonnot and others, 2011a; DeLonay and 

others, 2012; DeLonay and others, 2014). Although various 

habitat classification schemes have been proposed and applied 

to the Lower Missouri River, for the purposes of this report 

we will summarize data and break the Lower Missouri River 

into a minimally engineered section, an upstream channelized 

section, and a downstream channelized section (Reuter and 

others, 2009).

The section from Gavins Point Dam to the Big Sioux 

River (fig. 18) is the least engineered section of the Lower 

Missouri River including 59 miles of the Missouri National 

Recreational River (not shown), which retains much of the 

anabranching nature of the pre-dam river and has bare sandbars, variously vegetated islands, and multiple side channels 

(fig. 19) (Elliott and Jacobson, 2006). The minimally engineered segment has a range of depths, wide channel widths, 

and low mean velocities (fig. 20) (Reuter and others, 2009). 

A reach below Gavins Point Dam in the minimally engineered 

part of the Lower Missouri River has a substantial amount of 

coarse-bed substrate due to the presence of glacial materials 

and scouring downstream from the dam (fig. 21) (Laustrup and 

others, 2007; Elliott and others, 2009).

Downstream from Sioux City, Iowa, the Lower Missouri River has been channelized by the construction of 

wing dikes and bank revetment to create a single-threaded, 

self-scouring navigation channel managed by the U.S. 

Army Corps of Engineers (fig. 19). Nearly every outside 

bend on the channelized Lower Missouri River has been 

I

95°00' 90°00'

42°00'

40°00'

38°00'

0 50 100 200 MILES

Base from U.S. Geological Survey digital data, 2012, 1:100,000

Albers Equal-Area Conic projection

Osage River

Gasconade River

GAVINS POINT

DAM

St. Louis

Kansas City Boonville

St. Joseph

Nebraska City

Omaha

Sioux

City

IOWA

MISSOURI

KANSAS

NEBRASKA

ILLINOIS

Glasgow

Decatur

0 50 100 200 KILOMETERS

Rulo

Big

Sioux River

Platte River

Grand River

Kansas River

WISCONSIN

Missouri River

FORT RANDALL DAM

Figure 18. Lower Missouri River main stem and major tributary rivers within the Comprehensive Sturgeon Research Project 

study areas.
26 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

96°58' 96°56' 96°54' 96°52'

42°46'

42°44'

0 0.5 1 2 KILOMETERS

0 0.5 1 2 MILES

92°58' 92°56' 92°54' 92°52'

39°16'

39°14'

0 0.5 1 2 KILOMETERS

0 0.5 1 2 MILES

A

B

Digital Imagery from the U.S. Department of Agriculture National Aerial Imagery Program, 2012

Albers Equal-Area Conic projection

Digital Imagery from the U.S. Department of Agriculture National Aerial Imagery Program, 2012

Albers Equal-Area Conic projection

Figure 19. Examples of channel morphological variability in the Lower Missouri River. A, The minimally-engineered 

Gavins Point Dam to Big Sioux River segment. B, The channelized Grand River segment.
Figure 20. Distributions of habitat variables by Lower Missouri River sections, from Reuter and others (2009). The minimally engineered section extends from the Gavins Point Dam to the Big Sioux River. The upstream channelized section extends from Sioux City, Iowa to the Kansas River. The downstream channelized section extends from the Kansas River to the Mississippi River.

Minimally engineered

section frequency 

Upstream channelized

section frequency

Downstream channelized

section frequency

0

0.51.01.52.0

0

0.050.100.150.200.250.300.350.40

0

0.10.20.30.40.50.6

0

0.20.40.60.81.01.2

02468

10121416

0

0.050.100.150.200.250.300.350.40

0.00.10.20.30.40.50.6

0.00.51.01.52.0

0.00.20.40.60.81.01.2

02468

10121416

Depth bin, in meters

0

0.050.100.150.200.250.300.350.40

Depth slope bin, in degrees

0.00.10.20.30.40.50.6

Velocity bin, 

in meters per second

0.00.51.01.52.0

Velocity gradient bin, 

in percent per meter

0.00.20.40.60.81.01.2

Fro

02468

10121416 Depth Depth slope Velocity Velocity gradient Fr

0 2 4 6 8 10 12 14 0 5 10 15 20 25 30 0.0 0.5 1.0 1.5 2.0 2.5 0 2 4 6 8 10 0.0 0.1 

rol15-EMSB00-0040 Delonay Figure 21
28 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Figure 21. Natural potential spawning substrate in the Lower Missouri River. Data from Laustrup and others (2007). 

A, Gravel-cobble deposits. B, Bedrock adjacent to channel. 

95°00' 90°00'

42°00'

40°00'

95°00' 90°00'

42°00’

40°00'

U.S. Geological Survey Digital Data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 14

EXPLANATION

Deposit size, 

in acres

1

40

EXPLANATION

Bedrock 

exposure

NEBRASKA

IOWA

KANSAS

MISSOURI

ILLINOIS

NEBRASKA

IOWA

KANSAS

MISSOURI

ILLINOIS

A

B

0 50 100 200 KILOMETERS

0 50 100 200 MILES

Missouri River

Missouri River

rol15-EMSB00-0040 Delonay Figure 19
Sturgeon Habitat Variability within the Missouri River 29

armored with bank revetment consisting of coarse, angular, and variably sorted dolomite, limestone, or quartzite 

boulders. Wing, or spur dikes, also constructed of coarse 

hard rock, function to contract the natural channel and usually are constructed perpendicular to the thalweg or angling 

slightly downstream. Wing dike length controls the amount 

of channel constriction on a channelized river (Parchure, 

2005). Constricted channel width—measured as the distance between wing dike tips and the opposite bank—and 

the ratio of constricted to total width vary substantially 

along the river (fig. 22). Because the wing dikes control 

velocity contractions and expansions, these metrics are 

fundamental descriptors of habitat complexity.

The upstream channelized section of the Lower Missouri 

River extends downstream from Sioux City, Iowa (RM 735) 

to the Kansas River (RM 367). The number of dikes per mile 

along the entire Lower Missouri River is relatively uniform, at 

about 4.5–5 dikes per mile. Channel width for this segment of 

river is relatively low ranging from 143 to 343 m, with a mean 

width of 223 m (fig. 22). Superimposed on gradual downstream trends in channel morphology are several rather abrupt 

changes. Substantial changes in channel width, constricted 

width, and constriction ratio occur at tributary confluences 

(notably at the Platte, Kansas, Grand, and Osage River confluences) and near RM 500. Upstream from Rulo, Nebraska, 

dikes are shorter, with a mean length of 40 m, and thereby 

constrict the channel to a lesser degree than downstream 

from Rulo (fig. 22). Constricted width ranges in the upstream 

channelized section from 135–286 m, with a mean of 178 m. 

The constriction ratio between channel width and the width 

between the dike tip and the opposite bank ranges from 0–0.5 

and has a mean value of 0.2 (fig. 22).

Compared to the minimally engineered and downstream 

channelized section of the Lower Missouri River the upstream 

channelized section has fewer regions of shallow depths and 

low velocity (fig. 20). This section is also more dynamic. 

Surveys repeated during a 2-year period in a 6-km reach near 

the Little Sioux River documented substantial amounts of 

deposition and erosion occurring as large sandbars migrated 

down the channel. In places, the channel eroded or deposited 

3–4 m during the 2-year period yet maintained a low net rate 

of erosion and deposition for the reach as a whole (Elliott 

and others, 2009). A dynamic, shifting thalweg also has been 

documented through repeat surveys in other locations in the 

upstream channelized section of the Missouri River (Reuter 

and others, 2009).

Side channel and chute construction has been active in 

the upper channelized segment for habitat restoration, primarily upstream from Rulo, Nebraska (fig. 22). Dike notches, 

bank notches, and revetment notches also have been used 

to create habitat complexity in this part of the river. Valley 

widths are fairly wide although the river is occasionally in 

contact with the valley wall resulting in discontinuous reaches 

with natural bedrock exposures (Laustrup and others, 2007) 

(fig. 22).

In the downstream channelized section of the Lower 

Missouri River (Kansas River to the Mississippi River) the 

channel width ranges from 200 to 800 m with a mean width of 

400 m (fig. 22). Mean wing dike length is 100 m and constricted width ranges from 155 to 760 m (mean 275 m). Long 

wing dikes constrict the channel considerably, with constriction ratios as much as 0.6 (mean value is 0.3). Wing dikes 

create large recirculating eddies that tend to be associated 

with fine sediment deposition, areas of shallow water and low 

velocities, and emergent sandbars at lower discharges (Reuter 

and others, 2009; Tracy-Smith and others, 2012). There are 

also many small dikes and L-head dikes (L-head dikes are 

spur dikes with downstream extensions parallel to flow) on the 

lower channelized portion as illustrated by the wide range of 

constriction ratios (fig. 22).

Channel monitoring data for 2 years in a representative 

6-km reach near RM 262 documented that the channel was 

stable at the crossover-bend scale. In contrast to the upstream 

channelized section where sandbars migrated along the thalweg, channel-morphology dynamics in this part of the river 

system were limited to scour and fill during high-flow events in 

patches downstream from wing dikes or on point bars (Elliott 

and others, 2009). Natural and constructed chutes occur on the 

downstream channelized Missouri River, and many spur and 

L-head dikes and areas of bank revetment have been notched to 

create more habitat complexity (fig. 22) (Jacobson and others, 

2004a; Jacobson and others, 2004b). The Missouri River flows 

through a narrower valley as it enters the margin of the Ozark 

Plateaus Physiographic Province near RM 225. From RM 225 

to the mouth, the Missouri River has the highest concentration 

of natural bedrock in and adjacent to the river channel (Laustrup and others, 2007) (fig. 22).

Water quality downstream from Gavins Point Dam 

reflects the effects of the upstream reservoir system and 

progressive changes from downstream tributary inputs. The 

reservoir created by Gavins Point Dam, is relatively shallow 

and less likely to stratify compared to larger upstream reservoirs. The effect of the reservoir release on water temperature 

can be seen by examining the relation between air temperature, 

water temperature, and discharge at the Yankton, South Dakota 

streamgage. There is a near-linear 1:1 relation between air and 

water temperature, with departures for negative air temperatures that are not associated with negative water temperatures 

(not shown), and with maximum water temperatures that do not 

increase much above 25 o

C due to evaporative cooling (fig. 23). 

The one-to-one model explains 80 percent of the variation. The 

slope on the residuals is negative and very small, suggesting 

a slight tendency for colder water temperatures to be associated with high discharges; however, the relation is affected by 

discharges in excess of 50,000 ft3/s, and especially the very 

high discharges greater than 100,000 ft3/s in 2011. Operational 

releases for spring pulsed flows, for comparison, would rarely 

result in a release from Gavins Point Dam in excess of 47,000 

ft3/s for 2 days (U.S. Army Corps of Engineers, 2006) and so 

would not be expected to alter ambient water temperatures.
30 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012 Constricted width ratio

0.2

0.4

0.6

0.8

1.0

Big Sioux Segment, Nebraska and Iowa Grand Segment, Missouri

Valley width, 

in kilometers

0

5

10

15

20

25

30

Channel width, 

in meters

200

400

600

800

Valley width, 

in kilometers

0

5

10

15

20

25

30

Constricted 

width ratio

0.2

0.4

0.6

0.8

1.0

Flow constriction

Distance upstream from Mississippi River

700 600 500 400 300 200 100 0

1/1/2005

1/1/2007

1/1/2009

1/1/2011

1/1/2013

RIVERMILE vs DATE_ 

RM vs SpDate - 

RM vs SpDate - 

RIVERMIL_1 vs DATE1 

Channel width, 

in meters

200

400

600

800

St Louis,

Missouri

Sioux

City,

Iowa

Rulo,

Nebraska

Platte

River

Kansas

River

Grand

River

Osage

River

Distance upstream from Mississippi River

650 640 630 620 610 600

1/1/2005

1/1/2007

1/1/2009

1/1/2011

1/1/2013

250 240 230 220 210 200

Lamine

River

Pallid sturgeon

relocation

date

Pallid sturgeon

relocation

date Side channel

or 

chute location

Channel width

Channel width

to dike tips

EXPLANATION

Side channel or

chute location

Valley width

Bedrock adjacent 

to channel

Distance to right

valley wall

Distance to left

valley wall

Pallid sturgeon telemetry 

location

Pallid sturgeon migration

pathway habitat 

measurement location

Pallid sturgeon spawning

site habitat measurement

location

River miles from U.S. Army Corps of Engineers, 1960 

Designation, bedrock from Laustrup and others, 2009

rol15-EMSB00-0040 Delonay Figure 22

Figure 22. Channel width, flow constrictions (ratio between channel width and width between dike tip and opposite bank), side 

channel locations, valley width (bedrock wall to bedrock wall), and pallid sturgeon relocations and habitat data collection locations on 

the channelized Lower Missouri River from Sioux City, Iowa, to St. Louis, Missouri.
Sturgeon Habitat Variability within the Missouri River 31

Whereas water temperatures downstream from Gavins 

Point Dam are relatively insensitive to flow releases, relations to 

air temperature indicate that they are sensitive to cold weather 

events. Detailed comparisons by year of discharge, for water 

temperature, and air temperature document how water and air 

temperature covary most of the time (fig. 24). Flow pulses as 

much as 50,000 ft3/s are not obviously associated with multiday 

declines in water temperature. However, many water-temperature declines are strongly related in time to air-temperature 

declines, indicating that weather is a dominant control on multiday water-temperature variability in this segment. Flood releases 

in 2011 are an exception. Sustained high releases through the 

summer months were associated with a persistent lowering of 

water temperature below air temperature by as much as 10 °C.

Downstream from Gavins Point Dam water temperatures 

are affected by local tributary inflows. In general, seasonal 

water temperatures increase steadily from a median of 20.5 °C 

at Yankton, South Dakota to 24.2 °C at Hermann, Missouri 

(fig. 25). For reference, it has been estimated that optimal 

juvenile pallid sturgeon feeding temperature is 28 oC, and 

water temperatures are lethal to juvenile pallid sturgeon above 

35 oC (Chipps and others, 2008).

Other measures of water quality vary in expected ways 

downstream from Gavins Point Dam. The main-stem reservoir 

system is effective in attenuating major nutrients. Nitrogen 

and phosphorous increase downstream from the dam as nutrients are added from tributaries (Blevins and Fairchild, 2001; 

Brown and others, 2011). Because of the high turbidity of the 

Missouri River, light penetration is low and little of this nutrient load is assimilated in the river channel. Lack of opportunities for connection between the channel and overbank areas 

also limits opportunities for nutrient processing on floodplains. 

Average annual load of total nitrogen at Hermann, Missouri 

has been calculated as 210,000 MT/y and total phosphorous 

as 32,000 MT/y (Aulenbach and others, 2007). There is no 

evidence that these nutrient loads would directly affect pallid 

sturgeon, but they could increase primary productivity at lower 

levels of the foodweb in parts of the river or floodplain where 

water clarity is not limiting (Blevins, 2011).

Low dissolved oxygen concentration has been identified 

as a potential concern for pallid sturgeon and other fish species on the Lower Missouri River (Blevins, 2011). Dissolved 

oxygen concentrations less than 5 mg/L (a standard for warmwater fishes) occur with spring-summer floods and associated 

increased levels of turbidity; turbidity is indicative of influxes 

of nutrients and organic material from tributary basins. The dissolved oxygen responses (or sags) can be highly transient and 

only captured through continuous water-quality monitoring such 

as occurs at streamgaging stations (fig. 26). Although instances 

of dissolved oxygen sags have been documented (< 2.0 mg/L), 

it is not clear if they are of sufficient magnitude and duration to 

affect pallid sturgeon populations. In particular, it is not known 

how dissolved oxygen varies among habitat units on the river 

and whether fish can avoid areas with low levels. If low dissolved oxygen is deleterious to pallid sturgeon, it may be more 

likely at the free embryo or larval stages (Blevins, 2011).

Air temperature, in degrees Celsius

0 5 10 15 20 25 30 35

Water temperature, in degrees Celsius

0

5

10

15

20

25

30

35

Discharge, in cubic feet per second

0 50,000 100,000 150,000 200,000

Residual from linear regression

-15

-10

-5

0

5

10

WaterTemp=2.9+0.83×AirTemp

r 2 r 2

=0.80

Residual=0.2-0.000006×Discharge

=0.003

A B

rol15-EMSB00-0040 Delonay Figure 23

p<0.0001 p=0.048

Figure 23. Relation between air and water temperature in the Missouri River near Yankton, South Dakota. A, Least-squares linear 

regression between air temperature and water temperature. B, Least-squares linear regression between residuals (actual minus 

predicted) of the air temperature and water-temperature regression and discharge. The residual plot shows that water temperature is 

poorly correlated with discharge, accounting for air temperature.
0 50,000 100,000 150,000 200,000 

Discharge, in cubic feet per second 0 50,000 100,000

150,000200,000

0

50,000

100,000150,000200,000

Gavins Point Dam releases

Air temperature at Yankton, South Dakota

Water temperature at Yankton, South Dakota

Mar.

0

50,000

100,000150,000200,000

-10

0

10203040

Missing water temperature

Missing air 

EXPLANATION

Intentional pulse release

Intentional pulse relea

Intentional pulse release

Anomaly

Anomaly

Anomaly

Anomaly

Anomaly

Apr. May June July Aug.

Mar. Apr. May June July 

200620082010

200720092011

2012

rol15-EMSB00-0040 Delonay Figure 24 Figure 24. Plots of discharge from Gavins Point Dam and air and water temperature measured at Yankton, South Dakota, by year, 2006–12. Int

from Gavins Point Dam are identified as well as selected water-temperature anomalies where water temperature increases or decreases are temperature and not with discharge pulses.
Sturgeon Habitat Variability within the Missouri River 33

Water temperature, in degrees Celsius

0

5

10

15

20

25

30

35

Yankton,

South Dakota

Sioux City,

Iowa

Omaha,

Nebraska

Kansas City,

Missouri

Hermann,

Missouri

rol15-EMSB00-0040 Delonay Figure 25

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation 

below 10th percentile

Individual observation 

above 90th percentile

90th percentile

75th percentile

Figure 25. Seasonal (March through August) water-temperature distributions at sites on the Lower Missouri 

River from 2005 to 2012.

2009

Discharge, in cubic feet per second

0

50,000

100,000

150,000

200,000

250,000

300,000

Turbidity, in nephelometric turbidity units

0

200

400

600

800

1,000

1,200

1,400

Dissolved oxygen, in milligrams per liter

2

4

6

8

10

12

14

16

Discharge

Turbidity

Dissolved oxygen

Apr. 6 Apr. 20 May 4 May 18 June 01 June 15

EXPLANATION

rol15-EMSB00-0040 Delonay Figure 26

Figure 26. Example of water-quality variation at Hermann, Missouri, showing reciprocal relation of dissolved oxygen 

to discharge and turbidity. 
34 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Contaminants are listed as a potential threat to pallid 

sturgeon populations (Dryer and Sandvol, 1993), and there 

is some evidence for contaminant exposure along the Lower 

Missouri River. A study of contaminants in a female pallid 

sturgeon captured near RM 535 in 1988 indicated the presence 

of elevated levels of DDT and its metabolites, polychlorinated 

biphenyls (PCBs), chlordane, mercury, selenium, and cadmium (Ruelle and Keenlyne, 1993). Concentrations of PCB 

measured in the ovaries of the sturgeon were 28.5 mg/kg, 

far in excess of the Federal Food and Drug Administration’s 

action level for PCBs in edible fish of 2.0 mg/kg. Recent laboratory studies have indicated that persistent organic chemicals 

have potential to increase mortality of shovelnose sturgeon 

eggs and larvae (Buckler, 2011). Additionally, because of high 

PCB and chlordane content in shovelnose eggs, the State of 

Missouri has issued a no egg consumption advisory (Missouri Department of Health and Senior Services, 2011). A 

pilot study using longitudinal sampling of the Lower Missouri 

River with passive sampling devices demonstrated variable 

amounts of waterborne organochlorine (OC) pesticide residues 

from Sioux City, Iowa, to Hermann, Missouri, 1992 (Petty and 

others, 1995). Elevated concentrations of dieldrin, chlordane, 

DDT, and DDT metabolites were reported, generally increasing in the downstream direction with a peak at Glasgow, 

Missouri, followed by somewhat lower concentrations at 

Hermann. A follow-up study in 1994 included sampling for 

OC pesticides, PCBs, and polyaromatic hydrocarbons (PAHs) 

(Petty and others, 1998). This study confirmed that the concentration of these chemical contaminants may be variable 

among locations, again with a general pattern of increases in 

the downstream direction to a peak near Glasgow, Missouri, 

followed by diminished concentrations toward Hermann, 

Missouri. The study also documented substantial increases in 

OCs compared to those measured in 1992 and attributed the 

increase to the mobilization of contaminants during the 1993 

flood. Extracts from passively sampled water from an area 

of increased concentration were capable of triggering vitellogenin induction in rainbow trout, indicating that the mixture 

had potential to have an estrogenic effect on fishes in the Missouri River (Petty and others, 1998).

A subsequent study in 2002 sampled fine sediments in 

channel-margin environments from DeSoto, Iowa, to Jefferson 

City, Missouri, and confirmed a spatially variable distribution 

of sediment-hosted OC pesticides, PCBs, PAHs, and metals 

(Echols and others, 2008). The highest values of these substances were reported in the Kansas City, Missouri area, just 

downstream from the Kansas River; several sites exhibited 

concentrations of various substances, including some metals, 

exceeding expected ambient levels. This study concluded that 

the longitudinal distribution of contaminants was affected by 

point sources along the river, with major metropolitan areas 

like Kansas City being potentially important. The presence of 

OC pesticides (DDT, dieldrin, chlordane) and PCBs that have 

been banned for several decades indicates the potential for 

persistence and release of these substances from sediments. 

The authors noted that only a few sites had levels of metals 

or organic compounds that approached probable effects levels 

(Echols and others, 2008).

There are no definitive studies linking contaminants to 

reproductive failures or disease in pallid sturgeon. However, 

documented intersex, gonadal abnormalities, and teratomas in 

Missouri River sturgeon indicate the potential for endocrine 

disruption (DeLonay and others, 2009).

Comparative Physical Differences among Study 

Sections

Differences in physical characteristics among the study 

sections provide an experimental template that allows for 

learning through comparisons. The Yellowstone River provides a near-natural flow regime, sediment regime, channel 

morphology, thermal regime, and water quality. The Yellowstone River cannot qualify as an unimpacted reference 

condition because of impeded passage at Intake Dam and a 

shortened drift distance downstream to Lake Sakakawea. Nevertheless, the 73–mile segment downstream from Intake Dam 

provides near-natural habitats that can be used to assess migration and spawning for least-altered conditions. The Upper 

Missouri River also provides near-natural channel morphology 

and complexity but with highly altered flow, sediment, and 

thermal regimes. These two sections hold promise for isolating 

the role of flow regulation and thermal effects on the reproductive ecology of the species through comparison of pallid 

sturgeon migration, spawning, and drift behaviors. Unfortunately the comparison is imperfect because of uncontrollable 

factors such as flows entering the Upper Missouri River from 

the Milk, Redwater, and Poplar Rivers.

The Lower Missouri River allows for comparison with 

the upstream sections as well as a variety of conditions along 

the river. The degree of flow-regime alteration is highest 

immediately downstream from Gavins Point Dam, regaining 

much of the natural annual variability with increasing distance 

(fig. 5). Turbidity and temperature also increase gradually, 

providing a gradient against which some fish behaviors can be 

compared. In contrast to Fort Peck Dam releases, Gavins Point 

Dam releases do not depress water temperatures appreciably 

through a wide range of releases. This comparison helps isolate the effect of water temperature on reproductive ecology.

The 59 miles of river downstream from Gavins Point 

Dam has a complex channel morphology but highly altered 

flow, sediment, and water-quality regimes. Moving downstream, the Lower Missouri River is engineered to different 

degrees in different places, which is reflected in the channel 

characteristics of each segment (fig. 22). The gradient of variation in channel morphology provides opportunities to evaluate 

how morphological and hydraulic complexity contributes to 

habitat functions. In particular, variation in pallid sturgeon 

migration, spawning, drift, and settling behavior in different 

parts of the Lower Missouri River provides insights into how 

re-engineering the channel could promote reproduction and 

recruitment.
Sturgeon Habitat Variability within the Missouri River 35

Comparative Differences among Study Years

The CSRP field experiments include temporal variation 

superimposed on the physical variation of river segments. Year 

to year variability in flow regime and weather broadens comparative assessments but at the expense of replication. During 

the 2005 to 2012 period, annual runoff in the Missouri River 

Basin was highly variable, encompassing record high runoff 

in 2011 and an extreme drought year in 2006 (fig. 27). In most 

of the basin, 2005–08 was relatively dry and runoff increased 

into 2009–11.

In the Upper Missouri River, 2005 to 2012 was characterized by relatively steady releases from Fort Peck Dam 

and relatively steady flows downstream (fig. 28). Extreme 

discharges in 2011 were an exception. An April pulse from 

the Milk River pushed discharge at Culbertson, Montana, to 

nearly 30,000 ft3/s. The peak release of 66,000 ft3/s occurred 

in mid-June and combined with high flows from tributaries to 

achieve 97,000 ft3

/s at Culbertson. High releases extended into 

October. The flood pulse of 2011 was much higher and longer 

than other flood pulses on the Upper Missouri River for 2005 

to 2012, which were limited to no more than 15,000 ft3/s and 

occurred in 2005, 2007, 2008, 2010, and 2012 as a result of 

tributary floods.

In contrast, the Yellowstone River reported substantial 

spring-summer flood pulses in all years (fig. 28). Six of the 

eight years had dual-peaked flood pulses indicative of snowmelt 

from the plains and the Rocky Mountains. All years had peak 

flows in excess of 30,000 ft3

/s and remained above 10,000 ft3/s 

for at least 30 days. Discharge in 2011 was an extreme, peaking at 121,000 ft3

/s on May 25 and staying above 10,000 ft3/s 

for 145 days from April 18 to September 10. Comparisons of 

water temperature at downstream sites (Nohly, Montana, on the 

Missouri River and mile 2.5 on the Yellowstone River) indicate 

seasonal distributions with the Missouri River usually colder by 

a few degrees to as much as 10 ○C (fig. 28). The seasonal variation is marked by numerous short-term declines and peaks lasting from several days to a week. These excursions do not appear 

related on a one to one basis to flow pulses and are frequently 

synchronized in both rivers, indicating that they are related to 

weather events rather than flow or dam releases. The exceptions 

may be the prolonged cold anomalies on the Upper Missouri 

River in 2011 and 2012 (fig. 28).

On the Lower Missouri River, the 2005 to 2012 hydrologic record is highly variable among years and from upstream 

to downstream (fig. 29). Discharges from Gavins Point Dam 

are small in all years except for 2011 when releases peaked 

at 160,700 ft3/s on June 27 and stayed above 100,000 ft3/s for 

84 days, June 5 to August 28. Intentional spring pulse releases 

to enhance reproduction of pallid sturgeon occurred in May 

2006, March 2008, and May 2009 (fig. 29). The May 2006 

pulse release peaked at 25,000 ft3/s, the March 2008 release 

peaked at 18,000 ft3/s, and the May 2009 release peaked at 

23,000 ft3/s.

Year

2005 2006 2007 2008 2009 2010 2011 2012

Annual runoff, in millions of acre-feet

0

20

40

60

80

100

120

140

Upper Missouri River at Culbertson, Montana 

Yellowstone River near Sidney, Montana 

Lower Missouri River at Sioux City, Iowa 

Lower Missouri River at Hermann, Missouri 

EXPLANATION

Figure 27.rol15-EMSB00-0040 Annual runoff at four Missouri River system streamgages, 2005 to 2012 Delonay Figure 27 .
Daily discharge, in cubic feet per second 0 10,000 20,000 30,000

40,00050,00060,000

Jan.

0

10,00020,00030,00040,00050,00060,000

2008

2006

2007

2005

Upper Missouri River water temperature at Nohly, MontanaYellowstone River water temperature at river mile 2.5Upper Missouri River discharge from Fort Peck DamUpper Missouri River discharge at Wolf Point, MontanaUpper Missouri River discharge at Culbertson, MontanaYellowstone River discharge at Sidney, Montana

EXPLANATION

Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. June July May Aug. Sept

rol15-EMSB00-0040 Delonay Figure 28

Figure 28. Hydrographs and thermographs for the Upper Missouri River and Yellowstone River, 2005–2012, water-temperature data were collected 

discharge axis in 2011 is double the length of other years to accommodate flood conditions.
Daily discharge, in cubic feet per second

0

10,00020,00030,00040,00050,00060,000

0

10,00020,00030,00040,00050,00060,000

Daily discharge, in cubic feet per second

Water temperature, in degrees Celsius

05101520253035

2009 2010

0

20,00040,00060,00080,000

100,000120,000

2011

Jan. Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec.

05101520253035

2012

Jan. Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec.

Jan. Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. June July May Aug. Sept. 

Upper Missouri River waYellowstone River water Upper Missouri River disUpper Missouri River disUpper Missouri River disYellowstone River discha

EXPLANA

Figure 28. Hydrographs and thermographs for the Upper Missouri River and Yellowstone River, 2005–2012, water-temperature data were collected 

discharge axis in 2011 is double the length of other years to accommodate flood conditions.—Continued
Daily discharge, in cubic feet per second

0

50,000

100,000150,000200,000250,000300,000350,000

0

50,000

100,000150,000200,000250,000300,000350,000

20082006

2007

2005

Missouri River water temperature at Sioux City, IowaMissouri River water temperature at Boonville, MissouriMissouri River discharge from Gavins Point DamMissouri River discharge at Sioux City, IowaMissouri River discharge at Nebraska City, NebraskaMissouri River discharge at Boonville, Missouri

Jan. Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. June July May Aug. Sept

EXPLANATION

Intentional spring pulse releases

rol15-EMSB00-0040 Delonay Figure 29

Figure 29. Hydrographs and thermographs for the Lower Missouri River. Gaps in water temperature record result from ice conditions or malfunction
rol15-EMSB00-0040 Delonay Figure 29 continued

Daily discharge, in cubic feet per second

0

50,000

100,000150,000200,000250,000300,000350,000

0

50,000

100,000150,000200,000250,000300,000350,000

2011

2009 2010

2012

Jan. Feb. Mar. Apr. June July May Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. June July May Aug. Sept

Missouri River water temperature at Sioux City, IowaMissouri River water temperature at Boonville, MissouriMissouri River discharge from Gavins Point DamMissouri River discharge at Sioux City, IowaMissouri River discharge at Nebraska City, NebraskaMissouri River discharge at Boonville, Missouri

EXPLANATION

Intentional spring pulse releases

Figure 29. Hydrographs and thermographs for the Lower Missouri River. Gaps in water temperature record result from ice conditions or malfunction

Continued
40 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

The intentional spring pulses in the upstream section 

were small relative to uncontrolled flow pulses in the downstream section. In all years, the downstream section (Boonville, Missouri streamgage) had substantial spring pulses 

at least four times the discharge of the intentional releases. 

Pulses of 200,000 ft3/s or greater occurred in all years except 

2006 and 2012, which were the two driest years of the time 

period on the Lower Missouri River. The peak spring pulse 

discharge in 2006 was 96,000 ft3/s on May 3 and the peak in 

2012 was 133,000 ft3/s on April 18.

With the possible exception of 2006, all years at the 

downstream section had multiple spring pulses. The presence 

of multiple pulses complicates inferences that fish behavior 

can be associated with specific properties of one pulse, such as 

magnitude, timing, duration, and rate of change.

Water temperatures in each year indicate a seasonal pattern centered on a peak in late July—early August. Water temperatures in the upstream section (Sioux City, Iowa) are typically colder than those in the downstream section (Boonville, 

Missouri) by 1– 3 ○C. In 2011, Sioux City water temperatures 

were as much as 6 °C colder compared to Boonville. The seasonal arc of temperatures is disrupted by peaks and dips. Many 

of these anomalies are synchronous, but unrelated in time to 

flow pulses, implicating regional weather events (for example, 

declines in late April 2005, 2006, mid-September 2008, midJune 2009, and mid-August 2012). Among all years, one of 

the biggest temperature anomalies is the warm peak occurring 

throughout the region in mid-March to mid-April 2012.

Adult Life Stage

The adult life stage extends from the time the fish enters 

its first reproductive cycle until death. It consists of fish that 

are capable of spawning during the spawning season when 

gametes are mature and environmental conditions are correct 

(table 1).

Habitat Requirements for Adult Reproductive 

Fish

Before the initiation of CSRP studies, knowledge of the 

reproductive behavior and spawning habitats of pallid sturgeon was lacking and generally inferred from observations of 

the closely related shovelnose sturgeon (Moos, 1978; Keenlyne, 1997) or from broad generalizations of other sturgeon 

species (Kynard, 1997; Paragamian and Kruse, 2001; Bruch 

and Binkowski, 2002; Parsley and others, 2002). Studies by 

the CSRP have used minimally invasive assessment of reproductive readiness, telemetry, surgically implantable sensors, 

intensive tracking, acoustic sonar technologies, and a program 

of repeated recaptures of telemetered individuals to document 

habitat use, migration and spawning by pallid sturgeon (Wildhaber and others, 2005; Bryan and others, 2007; DeLonay 

and others, 2007; Wildhaber and others, 2007b; DeLonay and 

others, 2009; Wildhaber and others, 2011b; Albers and others, 

2013). Pallid sturgeon have been tagged with radio or acoustic telemetry transmitters in the Lower Missouri River and 

tracked extensively (monthly) throughout the year, and intensively (weekly to hourly) along their migration pathways to 

their spawning locations in the Lower Missouri River, Upper 

Missouri River below Fort Peck Dam, and in the Lower Yellowstone River (Fuller and others, 2008; DeLonay and others, 

2009; DeLonay and others, 2012).

The Comprehensive Sturgeon Research Project has used 

telemetry as part of a multidisciplinary approach in which 

telemetry is coordinated with physiological assessments of 

reproductive behavior and hydroacoustic habitat assessments 

(Bryan and others, 2007; DeLonay and others, 2007; Wildhaber and others, 2007b; DeLonay and others, 2009; Reuter 

and others, 2009; DeLonay and others, 2010; DeLonay and 

others, 2012; Albers and others, 2013; DeLonay and others, 

2014). The physiologic context provides an understanding of 

the reproductive state of a tagged fish, and thereby provides 

interpretation of why the fish behaves as it does (Wildhaber and others, 2007a, 2011a). Similarly, detailed habitat 

mapping around tagged fish locations places the behavior of 

individuals within a spatial context that allows researchers 

to characterize habitat availability and selection and thereby 

understand how channel morphology and flow regime can 

be managed to maximize reproduction and survival (Reuter 

and others, 2008; DeLonay and others, 2009; Jacobson and 

others, 2009b; Reuter and others, 2009; Bonnot and others, 

2011b).

This project has emphasized tagging male and female 

sturgeon in reproductive condition to focus on spawning cues, 

behaviors, and habitat (DeLonay and others, 2009; 2014). 

The tagging strategy of CSRP has emphasized retention of 

tagged individuals for study, and increasing the proportion of 

reproductive individuals in the study population to add power 

and statistical validity to the observations of rare individuals. 

Concerted efforts have been made to recapture, re-evaluate, 

and reimplant pallid sturgeon tagged and tracked in previous 

years.

Movement and Spawning Migration

Habitat use and movement data for adult, reproductively 

ready pallid sturgeon indicate consistent patterns of upstream 

migration before spawning (Fuller and others, 2008; DeLonay 

and others, 2009; DeLonay and others, 2010; DeLonay and 

others, 2012). Egg deposition at spawning sites is generally 

initiated after temperatures reach 16-18 °C (DeLonay and 

others, 2009). Pallid sturgeon generally spawned from late 

April through May in the Lower Missouri River (DeLonay 

and others, 2012), except during the unusually warm spring of 

2012 when spawning was documented as early as March 31 

(table 2) (DeLonay and others, 2014). Spawning in the Upper 

Missouri River generally occurs in mid-June through early 

July (Bramblett and White, 2001; Fuller and others, 2008; 

DeLonay and others, 2014).
Adult Life Stage 41

Female pallid sturgeon in the Lower Missouri River tend 

to exhibit one of two migration patterns: a single-apex pattern 

or a complex, disrupted up-and-downstream pattern (DeLonay 

and others, 2010). All female pallid sturgeon (n = 5) tracked 

during 2005 to 2012 to their spawning locations in the Lower 

Missouri River study section downstream from the Kansas 

River exhibited the characteristic single-apex migration pattern, 

tending to spawn successfully at the apex of their migration 

from late April through the first two weeks of May (DeLonay 

and others, 2009; 2010b; 2012a) (table 2, fig. 30). Only one of 

five tracked female pallid sturgeon in the Lower Missouri River 

segment, upstream from the Kansas River, exhibited the singleapex migration pattern, spawning in late April (DeLonay and 

others, 2012). The remaining four females exhibited complex 

or disrupted patterns (fig. 31). Females with a disrupted or 

complex migratory pattern tended to spawn later or did not successfully spawn and their ovaries showed evidence of atresia 

(DeLonay and others, 2012). More observations are needed to 

substantiate observed patterns and to relate subsequent spawning success to environmental conditions.

Pallid sturgeon migration patterns in the Yellowstone and 

Upper Missouri Rivers are also complex, and do not show the 

characteristic single-apex patterns observed in Lower Missouri 

River pallid sturgeon and shovelnose sturgeon (Bramblett and 

White, 2001; Fuller and others, 2008; DeLonay and others, 

2009; Wildhaber and others, 2011b) (see appendix 4). Upper 

Missouri River pallid sturgeon typically begin migration with 

rising temperatures and increasing flows from the Yellowstone River. The lack of sufficient miles of free-flowing river 

and a partial barrier at Intake Dam, Montana, likely disrupt 

the migration behavior and prevent fish from using upstream 

spawning sites. Fish unable to pass the dam eventually retreat 

downstream and successively repeat upstream movements 

until environmental conditions are conducive to spawning at 

a downstream location (DeLonay and others, 2014). Modified 

flows, altered temperatures, and reduced turbidity resulting 

from hypolimnetic releases from Fort Peck Dam may affect 

migration patterns and rates in the Upper Missouri River, 

similar to pallid sturgeon in the study section of the Lower 

Missouri River nearest to Gavins Point Dam. Although the 

2008

Fish depth, in meters

0

2

4

6

8

10

12

14

Temperature, in degrees Celsius

5

10

15

20

25

30

35

Discharge, in one thousand cubic feet per second

0

10

20

30

40

50

60

70

80

90

100

Missouri River location, in river miles

150

200

250

300

350

400

Fish depth from archival tag

Water temperature from archival tag

Missouri River discharge

Missouri River temperature

Missouri River telemetry location

Initial capture, tag implantation, and release

Recapture

EXPLANATION

April 1 May 1 June 1 July 1 August 1 September 1

rol15-EMSB00-0040 DeLonay Figure 30

Figure 30. Characteristic, single-apex migration pattern of female pallid sturgeon in the lower study section of the Lower Missouri 

River as illustrated by PLS08-009. Depth and temperature recorded from data storage tag, discharge from the nearest streamgage 

at Boonville, Missouri, and telemetry locations for implanted gravid pallid sturgeon PLS008-009. Fish was implanted in reproductive 

condition, later recaptured, and determined to have spawned.
42 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Table 2. Probable spawning locations of telemetry tracked reproductive female pallid sturgeon, 2007–12.

[FishID, Fish identification code; >, greater than; <, less than; NA, not available; Nebr., Nebraska]

Spawning site 

confidence 

score1

FishID

Spawning period2 Boundary of probable spawning extent3 

Spawning 

year

Spawning 

begin date

Spawning 

end date

Upstream extent, 

in river miles

Downstream extent, 

in river miles

Center of 

spawning site

3 PLS07-004 2007 5/17/2007 5/23/2007 >768.7 756.3 NA 

3 PLS07-007 2007 4/29/2007 5/8/2007 >694.9 681.1 NA 

1 PLS08-004 2008 5/4/2008 5/5/2008 230.7 230.0 230.4 

1 PLS08-008 2008 5/8/2008 5/9/2008 366.8 366.1 366.4 

1 PLS08-009 2008 5/7/2008 5/8/2008 369.7 369.3 369.5 

3 PLS08-014 2008 5/22/2008 5/31/2008 688.4 670.7 NA 

3 PLS07-001 2008 NA 6/3/2008 811.0 790.7 NA 

1 PLS09-007 2009 4/25/2009 4/26/2009 206.1 206.5 206.3 

2 PLS09-009 2009 5/7/2009 5/11/2009 659.8 650.3 NA 

1 PLS10-006 2010 4/30/2010 5/1/2010 202.4 202.0 202.2 

1 PLS10-013 2010 4/28/2010 4/29/2010 634.2 633.7 633.9 

5 PLS10-023 2010 5/13/2010 5/26/2010 642.7 494.9 NA 

3 PLS07-001 2011 5/8/2011 5/23/2011 799.6 (3.3) 787.1 NA 

1 PLS11-008 2011 5/17/2011 5/19/2011 216.8 215.9 216.4 

4 PLS11-014 2011 NA NA Missouri River, 

Nebr.

NA NA 

4 PLS11-015 2011 NA NA Platte River, 

Nebr.

NA NA 

4 PLS11-016 2011 NA NA Platte River, 

Nebr.

NA NA 

4 PLS11-017 2011 NA NA Missouri River, 

Nebr.

NA NA 

4 PLS11-020 2011 NA NA Platte River, 

Nebr.

NA NA 

1 PLS11-007 2012 3/31/2012 3/31/2012 322.2 322.2 322.2 

3 PLS11-019 2012 5/5/2012 5/31/2012 713.7 700.1 NA 

1 PLS09-011 2012 4/26/2012 4/26/2012 580.6 579.8 580.2 

4 PLS10-029 2012 NA NA Platte River, 

Nebr.

NA NA 

1

1=probable spawning site located within > 1 river mile; 2=probable spawning site located within 1–10 miles; 3=probable spawning site located within 

10–25 miles; 4=probable spawning site located within 25–100 miles; 5=probable spawning site located within >100 miles.

2

The act of spawning by a female sturgeon may take from 8 to 24 hours. The spawning begin and end dates indicate the time during which spawning may 

have occurred for an individual fish. The time period reported reflects the uncertainty surrounding the actual timing of the spawning event, not the actual time 

spent spawning by an individual.
Adult Life Stage 43

Tracking details4

Notes

Pre-spawn 

evaluation Tracking Spawning confirmed

Yes Intensive Yes Spawning occurred in unchannelized river. Tracking boats could not follow fish at night and lost contact. Complete migration and spawning not observed.

Yes Intensive Yes Intensive tracking interupted by lethal tornado. Complete migration and spawning not documented.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Intensively tracked female showed complex disrupted pattern. Complete migration pattern documented, but spawning behavior difficult to discern.

No Extensive Yes Female not intensively tracked. Recovered in July after spawning season with spent ovaries indicating 

she had spawned that spring, most likely prior to downstream movement. Minimal observations suggest that this fish most likley spawned in the unchannelized reach above 790.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive No Female intensively tracked and aggregations with males documented, but female not recovered. 

Spawning not verified.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Translocated fish from propagation program. Intially intensively tracked as it moved upstream to 

spawn. It reached its upstream apex and began moving downstream. It was recovered on May 13 after its intial downstream movement and it had not yet spawned. It was recovered again June 9 more 

than nearly 150 miles downstream and it had spawned.

Yes Intensive Yes Intensively tracked. Complete migration documented. Complex, disrupted migrations. May have 

spawned in the James River. Most likely spawning location is in the Missouri River. Spawning 

behavior not documented. 

Yes Intensive Yes Intensive tracking to spawning location. Complete migration documented. Spawning behavior not 

documented.

Yes NA Yes The fish was not located during the spawning period. Spawning location is inferred from data storage 

tag records of temperature matching the temperature profile of the mainstem Missouri River, Nebr.

Yes NA Yes The fish was not located during the spawning period. Spawning location is inferred from data storage 

tag records of temperature matching the temperature profile of the Platte River, Nebr.

Yes NA Yes The fish was not located during the spawning period. Spawning location is inferred from data storage 

tag records of temperature matching the temperature profile of the Platte River, Nebr.

Yes NA Yes The fish was not located during the spawning period. Spawning location is inferred from data storage 

tag records of temperature matching the temperature profile of the mainstem Missouri River, Nebr.

Yes NA Yes The fish was not located during the spawning period. Spawning location is inferred from data storage 

tag records of temperature matching the temperature profile of the Platte River, Nebr.

Yes Intensive Yes Intensive tracking to spawning location. Complete migration and spawning behavior documented.

Yes Intensive Yes Intensively tracked female showed complex distrupted pattern. Complete migration pattern and spawning behavior not documented. Spawning confirmed but spawning behavior difficult to discern.

Yes Intensive Yes Intensive tracking to spawning location. Female showed complex, disrupted migration. Spawning 

behavior documented.

No NA Yes The fish was not evalauted prior to spawning, but was recaptured in post-spawn condtion with few remaining oocytes in 2012. The fish was not located during the spawning period. Spawning location is 

inferred from data storage tag records of temperature matching the temperature profile of the Platte 

River, Nebr.

3

The spawning of an individual sturgeon occurs over a fairly limited area. As we understand it, spawning by pallid sturgeon may occur over a patch of spawning habitat ranging from 0.3 to 0.7 river miles in length. The upstream and downstream extents reported reflect the uncertainty surrounding where the patch of 

spawning habitat is located, not the extent over which the individual actually deposited eggs. Values in parentheses are river miles in a Missouri River tributary. 

In some instances the female sturgeon was tracked to the probable spawning site and spawning behavior was documented. In this case a river mile for the center 

of the spawning habitat patch is reported.

4

The tracking details indicate whether the female sturgeon was evaluated for reproductive condition in the months just prior to spawning, if the sturgeon was 

targeted for intensive tracking (daily) or extensively tracked as resources allowed, and if the female sturgeon was recaptured following spawning to confirm that 

eggs had been released successfully.
44 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

tagged individuals in the Upper Missouri River are substantially larger than those in the Lower Missouri River, and their 

migration constrained by barriers, the documented migration 

distances of reproductive adults are similar among populations 

(Fuller and others, 2008; DeLonay and others, 2009).

Migration patterns of reproductively ready male pallid sturgeon in the Lower Missouri River are less regular 

than those of females and may include upstream and downstream movements at or near the apex of migration, giving 

the impression that they are actively searching for mates or 

occupying multiple spawning sites during the spawning season 

(DeLonay and others, 2012). Similar patterns were observed 

among male shovelnose sturgeon in the Lower Missouri River 

(DeLonay and others, 2009). Insufficient numbers of male 

pallid sturgeon have been tagged in the Lower Missouri River 

to document spawning aggregations and to resolve whether 

males migrate and select spawning locations in advance of 

the arrival of females, as exhibited by other sturgeon species 

(Bruch and Binkowski, 2002). Low population densities of 

reproductive sturgeon may contribute to complex migration 

patterns, as individuals may need to actively search for conspecifics. Aggregations of males have been documented in the 

Lower Yellowstone River, and areas of frequent aggregations 

are coincident with sites where spawning by females has been 

documented (Bramblett and White, 2001; Fuller and others, 

2008; DeLonay and others, 2014).

Observations of tagged fish have increased with successive years, and as a result a greater understanding of the 

complex seasonal spawning migrations in the Lower Missouri 

River has emerged. In 2010 and 2011 several female pallid 

sturgeon anticipated to spawn in the coming spring exhibited 

a fall pre-spawning migration, followed by a shorter subsequent spring migration to the final spawning location (fig. 32). 

PLS11-007, for example, is a female pallid sturgeon captured 

rol15-EMSB00-0040 DeLonay Figure 31

Fish depth, in meters

0

2

4

6

8

10

12

14

Temperature, in degrees Celsius

-5

0

5

10

15

20

25

30

35

Discharge, in one thousand cubic feet per second

0

20

40

60

80

100

120

140

160

180

200

Missouri River location, in river miles

660

670

680

690

700

710

720

730

2012

Fish depth from archival tag

Water temperature from archival tag

Missouri River discharge

Missouri River temperature

Missouri River telemetry location

Recapture

EXPLANATION

March 5 March 19 March 16 April 16 April 30 May 14 May 28 June 11

Figure 31. Characteristic complex or disrupted migration pattern in the upper study section of the Lower Missouri River as illustrated 

by PLS09-011. Depth and temperature recorded from data storage tag, discharge from the nearest streamgage at Nebraska City, 

Nebraska, and telemetry locations for implanted gravid pallid sturgeon PLS09-011. Fish was implanted in reproductive condition, later 

recaptured, and determined to have spawned.
Adult Life Stage 45

in nonreproductive condition during April 2011 near RM 200. 

This female remained relatively stationary through the summer of 2011. A reproductive evaluation performed on September 16, 2011, indicated this female would be ready to spawn 

during spring 2012. From late September through December 

she moved upstream about 100 RM, to a location near RM 296 

where she spent the winter. During March 2012, PLS11-007 

moved upstream about 20 miles to near RM 322 and initiated 

spawning behavior on March 31, 2012. Female PLS11-007 

was recaptured on April 3, 2012, and found to have spawned 

completely. It is unknown what prompts some fish to migrate 

a distance upstream in the fall, stop, then finish the migration 

during the next year’s spawning season, and others to complete their spawning migration in a single-step journey during 

spring. Fall upstream migration of pallid sturgeon from the 

Upper Missouri River into the Yellowstone River does not 

occur, perhaps because flows in the Yellowstone River decline 

in late summer and fall, whereas flows in the Lower Missouri 

River do not typically exhibit historical patterns of low summer or winter flows.

Movement patterns of nonreproductive adult pallid 

sturgeon indicate patterns of behavior and migration differ 

between sexes. Nonreproductive females tend to remain relatively stationary, using a single bend or small habitat patch, 

whereas nonreproductive males may remain relatively stationary or they may migrate substantial distances (>50 miles) 

upstream (fig. 33). Depth-use data from implanted data-storage 

tags also indicate a difference between sexes. Pallid sturgeon 

females consistently use a wider range and greater depths than 

males. The differences in depth use between the sexes is less 

pronounced in years when they are in reproductive condition 

compared to years when they are nonreproductive (fig. 34). 

rol15-EMSB00-0040 DeLonay Figure 32

Fish depth, in meters

0

2

4

6

8

10

12

14

Temperature, in degrees Celsius

-5

0

5

10

15

20

25

30

35

Discharge, in one thousand cubic feet per second

0

50

100

150

200

250

300

Missouri River location, in river miles

180

200

220

240

260

280

300

320

340

Fish depth from archival tag

Water temperature from archival tag

Missouri River discharge

Missouri River temperature

Missouri River telemetry location

Recapture

Initial capture, tag implantation and release

EXPLANATION

March 1,

2011

July 11,

2011

November 1,

2011

July 1, 

2012

March 1,

2012

November 1,

2012

March 1, 

2013

Figure 32. Fall migration followed by characteristic, single-apex spring migration pattern of female pallid sturgeon in the lower study 

section of the Lower Missouri River as illustrated by PLS11-007. Depth and temperature recorded from data storage tag, discharge 

from the nearest streamgage at Boonville, Missouri, and telemetry locations for implanted gravid pallid sturgeon PLS11-007. Fish was 

assessed before fall migration in 2011 and determined to be ready to spawn in spring 2012. It was recaptured and determined to have 

spawned.
46 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

C. Nonreproductive males

Spawn year (September 1–August 31)

Sept. Nov. Jan. Mar. May July Sept.

Migration distance, in kilometers

-1,000

-750

-500

-250

0

250

500

750

1,000

A. Reproductive males

-1,000

-750

-500

-250

0

250

500

750

1,000

D. Nonreproductive females

Sept. Nov. Jan. Mar. May July Sept.

B. Reproductive females

Number of tracks = 25 Number of tracks = 25

Number of tracks = 34 Number of tracks = 68

Figure 33. Migration distance of adult pallid sturgeon tracked during the spawn year (September 1st to August 

31st) from 2005 to 2012. Migration distance represents upstream (+) and downstream movements. Fish had to be 

located at least three times to be included in these plots. Fish are grouped using their sex and reproductive status 

during the spawn year: reproductive or nonreproductive separately for males and females. Multiple lines can be 

from the same fish if the fish was followed for more than one spawn year.
Adult Life Stage 47

We cannot yet explain the observed differences in depth use 

between pallid sturgeon males and females, although real differences in depth use would suggest that the sexes are using 

different habitats or similar habitats differently.

Past investigations of habitat use during migration and 

upstream migration pathways of pallid sturgeon culminated in 

intensive, multidisciplinary studies in 2010–12. These studies 

were designed to explore whether upstream migration may be 

impeded, especially in the channelized Lower Missouri River, 

and to quantify velocities of pathways selected by fish during 

upstream migration. Telemetry-tagged pallid sturgeon from the 

upstream and downstream channelized sections of the Lower 

Missouri River and Yellowstone River were selected for intensive mapping of habitat use during migration. Pre-spawning 

evaluations of the fish selected for mapping on the channelized 

Lower Missouri River in March and April of all years ranged 

from 874–1,102 mm fork length (FL) and weighed from 

2,710–6,800 grams (table 3). Five out of the nine reproductive females were recaptured and determined to have spawned 

after migration. Two additional females on the Lower Missouri 

River went atretic, or re-absorbed their eggs, and the spawning 

status of the additional two females on the Yellowstone River 

is unknown.

Sturgeon migration pathways were mapped using precise 

locations from acoustic telemetry on the Lower Missouri River 

and radio telemetry on the Yellowstone River. Four reciprocal 

transects (pairs of transects surveyed traveling in both directions perpendicular to the flow) were driven across the channel 

perpendicular to fish locations using Hypack navigation software, a differential Global Positioning System, and an acoustic 

Doppler current profiler (ADCP) (DeLonay and others, 2012; 

McElroy and others, 2012; DeLonay and others, 2014). With a 

few exceptions habitat measurements were made at discharges 

that were within 10 percent of the discharge at the time of fish 

movement (table 4). Output ADCP files were summarized 

using automated scripts to map transects in a Geographic 

Information System (GIS) and to extract the minimum, 

maximum, and mean velocity per vertical ensemble (profile 

of velocities at increasing depths from the surface to near the 

bottom) and the depth at that ensemble. Selectivity of habitat 

characteristics was calculated using Ivlev’s selectivity coefficient (Manly and others, 2002; Reuter and others, 2009).

The complete dataset included a total of 445 reproductive pallid sturgeon migration locations making up 40 distinct 

pathways from 22 individual fish (table 4). Pathways were 

recorded by following individual sturgeon continuously 

through a river bend or side channel and recording telemetry 

locations at frequencies ranging from once every 15 minutes 

to hourly, depending on the rate of travel. Pathways from the 

same individual on different dates were considered distinct. 

All locations represented pathways of 3–23 locations of 

upwardly migrating telemetered pallid sturgeon with a mean 

number of 11 fish locations making up a pathway. Twenty-two 

individual fish were represented with 9 females and 13 males 

(table 4). The dataset included migration pathways for April 

through June from 2010 to 2012 in three Missouri River and 

Yellowstone River sections. Most of the migrating males (12) 

were from the Yellowstone River, and 6 females were from the 

Lower Missouri River.

Fish migration pathways examined ranged from 0.3 to 

11.2 km long (mean 3.7 km) representing intensive telemetry 

tracking periods from 41 minutes to nearly 24 hours. The average tracking pathway time period was 7 hours and 38 minutes. 

Total migration distance is unknown, as fish were not tracked 

during their entire migration period. Minimum migration distances were calculated using known telemetry locations for the 

fish from initial assessment in the spring to spawn date on the 

Lower Missouri River, and by using telemetry locations from 

May and June on the Yellowstone River. Minimum migration 

distances ranged from 20 to 190 miles. Several fish on the 

rol15-EMSB0-0040 Delonay Figure 34

Nonreproductive

female

Mean depth, in meters

0

2

4

6

8

10

Reproductive

female

Reproductive

male

Nonreproductive

male

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 10th percentile

Individual observation above 90th percentile

90th percentile

75th percentile

Figure 34. Mean depth of pallid sturgeon collected from 

retrieved data storage tags. Reproductive status during the spawn 

year (September 1st to August 31st).
Table 3. Habitat mapping data collected for reproductive pallid sturgeon in migration study from 2010–12. [FishID, Fish identification code; --, no data] Year mapped River section Acoustic or radio code number FishID Sex Date of evaluation Weight, in kilograms Fork length, in millimeters Spawn i

2010 Lower Missouri River, Missouri 1053 PLS10-006 Female 4/15/2010 3.55 932 Complete spa

2010 Lower Missouri River, Nebraska and Iowa 1066 PLS10-023 Female 4/28/2010 4.496 1,000 Complete spa

2010 Lower Missouri River, Nebraska and Iowa 1057 PLS08-014 Female 3/9/2010 2.855 923 Atretic May 2

2011 Lower Missouri River, Missouri 1139 PLS11-003 Male 3/23/2011 2.71 874 Unknown 

2011 Yellowstone River, Montana 156 and 230 Female 6/15/2011 17 1,362 Unknown 

2011 Yellowstone River, Montana 70 Male 5/21/2009 13 1,346 Unknown 

2011 Yellowstone River, Montana 142 Male 5/25/2010 19 1,435 Unknown 

2011 Yellowstone River, Montana 119 and 272 Male 5/19/2009 14.5 1,412 Unknown 

2012 Lower Missouri River, Nebraska and Iowa 1155 PLS09-011 Female 3/23/2012 4.655 980 Complete spa

2012 Lower Missouri River, Nebraska and Iowa 1125 PLS11-019 Female 3/15/2012 6.8 1,102 Complete spa

2012 Lower Missouri River, Nebraska and Iowa 1143 PLS10-023 Female 4/13/2012 5.46 1,019 Atretic May 2

2012 Yellowstone River, Montana 51 Male 5/8/2012 14.5 1,385 Unknown 

2012 Yellowstone River, Montana 36 Female 4/26/2012 17.5 1,333 Probable spaw

2012 Yellowstone River, Montana 37 Female 4/23/2012 15 1,350 Unknown 

2012 Yellowstone River, Montana 272 and 119 Male 5/9/2012 -- -- Unknown 

2012 Yellowstone River, Montana 55 Male 4/25/2012 17.5 1,451 Unknown 2012 Yellowstone River, Montana 16 Male 5/12/2009 20 1,400 Unknown 2012 Yellowstone River, Montana 92 Male 10/15/2008 22 1,468 Unknown 2012 Yellowstone River, Montana 52 Male 4/24/2012 18.75 1,483 Unknown 2012 Yellowstone River, Montana 69 Male 5/9/2012 6 1,120 Unknown 2012 Yellowstone River, Montana 76 Male 5/8/2012 11.25 1,220 Unknown 2012 Yellowstone River, Montana 230 and 156 Female 4/25/2012 17 1405 Successful sp

1Radio code in 2011. 2Radio code in 2012.
Adult Life Stage 49

Yellowstone River traveled distances greater than 150 miles, 

which included multiple movements up and downstream in the 

73 miles downstream from Intake Dam.

Habitat measurements are representative of discharges 

on the Yellowstone and Lower Missouri Rivers during spring 

pallid sturgeon migrations and were made at flow percentiles 

ranging from 50 to100 percent of the historical record from 

1970 to 2012 (table 4). Lower Missouri River discharges in the 

upstream channelized section fell within the 50–80th percentile range. Discharges in the downstream channelized Missouri 

River fell within the 60–90th percentile and Yellowstone River 

discharges fell within the 90–100th percentile range.

Migrating sturgeon used depths on the Yellowstone River 

in similar proportion to the range of available depths (fig. 35, 

table 5). Velocities also were used in similar proportion to 

available velocities on the Yellowstone River, with Ivlev’s 

selectivity coefficient suggesting avoidance of velocities at 

the high and low ends of the distribution. In the Yellowstone 

River there were several examples of migrating sturgeon using 

chutes and secondary channels as well as the main channel. 

Two pallid sturgeon were tracked on their approach to Intake 

Dam (see appendix 4).

In the upstream channelized Lower Missouri River in 

Nebraska and Iowa, pallid sturgeon used depths representing 

the ranges of depths and velocities available to them with the 

exception of avoidance of very shallow areas. Velocity use 

data indicated sturgeon using most of the range of velocities 

available to them with a similar pattern of avoiding velocities on the low and high ends of the distribution (greater than 

1.5 meters/second [m/s]). In contrast, sturgeon in the downstream channelized Lower Missouri River in Missouri selected 

for very shallow and very deep places in the channel, and 

velocities on the low end of the distribution. Sturgeon avoided 

velocities greater than 2.0 m/s in the downstream channelized 

Lower Missouri River.

Migration results in the downstream channelized Lower 

Missouri River support the model presented by McElroy and 

others (2012) that suggests that pallid sturgeon select the 

least-cost pathway during their migration, optimizing energy 

expenditure by moving along inside bends and moving laterally across channels at crossovers. Pallid sturgeon throughout the upstream channelized Lower Missouri River and on 

the Yellowstone River selected less distinct, less repeatable 

pathways, possibly because they do not need to avoid high 

velocities in the navigation channel; ranges of velocities available for sturgeon migration during the period of measurements 

were much lower than those on the downstream channelized 

Lower Missouri River in Missouri. Mean depth-averaged 

velocities used by migrating pallid sturgeon was similar on 

the Yellowstone River (1.20 m/s available, 1.18 m/s used) and 

the upstream channelized Lower Missouri River in Nebraska 

and Iowa (1.16 m/s available, 1.14 m/s used) (table 5). Mean 

depth-averaged velocities used for migration were lower than 

available (1.72 m/s available, 1.27 m/s used) on the downstream channelized Lower Missouri River. The characteristic 

use of inside bends and crossovers for upstream migration in 

the Lower Missouri River may be enhanced, in part, by avoidance of the engineered navigation channel. Adverse conditions 

in the navigation channel and reduced slow velocity marginal 

area may narrow the width of suitable upstream migration 

pathways selected by sturgeon, and also may explain the use 

of side channels during migration.

Spawning Habitat

Comprehensive Sturgeon Research Project studies in the 

Lower Missouri River from 2007 through 2012 have documented 19 spawning events, 12 in the upper study section 

and 7 in the lower study section of the Lower Missouri River 

(table 2). Pallid sturgeon also are suspected of spawning in the 

Platte River based on extensive tracking data and comparative examination of archival temperature data from surgically 

implanted data storage tags with temperature loggers or USGS 

streamgage stations (DeLonay and others, 2012). Spawning 

in each case was verified through recapture and reassessment of female reproductive status using minimally invasive 

ultrasonography with surgical verification. No viable pallid 

sturgeon eggs or free embryos have been collected immediately downstream from spawning sites on the Lower Missouri 

River; therefore, fertilization and thus survival through hatch 

have not been demonstrated in these study sections.

Studies on the Upper Missouri River have demonstrated 

that spawning has resulted in fertilization and survival through 

the free-embryo stage. CSRP studies documented one spawning location in 2011 on the Upper Missouri River downstream 

from the confluence with the Milk River inferred from an 

aggregation of males and the collection of a genetically 

confirmed pallid sturgeon free embryo (DeLonay and others, 

2014). A second spawning location was identified in 2012 

on the Lower Yellowstone River based on aggregations of 

tagged male and female pallid sturgeon, recovery of ripe males 

accompanied by a tagged female releasing eggs, and the subsequent collection of a genetically confirmed pallid sturgeon 

free embryo. Genetic parentage analyses indicated that neither 

of the free embryos collected in 2011 or 2012 were progeny 

of tracked pallid sturgeon located at the probable spawning 

sites suggesting that multiple females spawned in each area 

(DeLonay and others, 2014).

The precision with which the timing of spawning and 

spawning locations were determined on the Lower Missouri 

River varied among individuals tracked depending on the 

tracking strategy used and recapture success, which varied 

from year to year based on the number of available gravid 

females, logistics associated with geographic distributions of 

tagged fish, and river conditions. Females tracked with high 

frequency near their spawning locations indicated that spawning occurred within a few hundred meters along an outside 

river bend within a 36-hour period. Estimates of the timing 

and location of spawning of other telemetered females were 

less precise, especially when the migration pattern was complex, disrupted, lacked clear observation of spawning behavior, or if the females were only tracked extensively or at low 
50 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Table 4. Pallid sturgeon migration pathways mapped in 2010–12.

[FishID, Fish identification code]

Pathway 

number

Fish 

movement 

date

Location

Acoustic or 

radio code 

number

FishID

Number of 

fish 

locations

Streamgage

1 4/21/2010 Missouri River, Missouri 1053 PLS10-006 8 Boonville, Missouri 

2 4/28/2010 Missouri River, Missouri 1053 PLS10-006 16 Boonville, Missouri 

3 4/29/2010 Missouri River, Missouri 1053 PLS10-006 4 Boonville, Missouri 

4 4/30/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 5 Decatur, Nebraska 

5 5/1/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 14 Decatur, Nebraska 

6 5/2/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 12 Decatur, Nebraska 

7 5/3/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 14 Decatur, Nebraska 

8 5/4/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 23 Decatur, Nebraska 

9 5/5/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 12 Decatur, Nebraska 

10 5/6/2010 Missouri River, Nebraska and Iowa 1066 PLS10-023 8 Decatur, Nebraska 

11 5/19/2010 Missouri River, Nebraska and Iowa 1057 PLS08-014 18 Decatur, Nebraska 

12 5/20/2010 Missouri River, Nebraska and Iowa 1057 PLS08-014 22 Decatur, Nebraska 

13 4/30/2011 Missouri River, Missouri 1139 PLS-11-003 9 Boonville, Missouri 

14 6/3/2011 Yellowstone River, Montana 156 and 230 3 Sidney, Montana 

15 6/4/2011 Yellowstone River, Montana 156 and 230 3 Sidney, Montana 

16 6/6/2011 Yellowstone River, Montana 70 4 Sidney, Montana 

17 6/7/2011 Yellowstone River, Montana 142 3 Sidney, Montana 

18 6/8/2011 Yellowstone River, Montana 119 and 272 9 Sidney, Montana 

19 6/9/2011 Yellowstone River, Montana 119 and 272 3 Sidney, Montana 

20 4/19/2012 Missouri River, Nebraska and Iowa 1155 PLS09-011 15 Decatur, Nebraska 

21 4/25/2012 Missouri River, Nebraska and Iowa 1125 PLS11-019 13 Decatur, Nebraska 

22 4/11/2012 Missouri River, Nebraska and Iowa 1155 PLS09-011 11 Nebraska City, Nebraska 

23 4/18/2012 Missouri River, Nebraska and Iowa 1143 PLS10-023 12 Nebraska City, Nebraska 

24 5/2/2012 Missouri River, Nebraska and Iowa 1125 PLS11-019 10 Decatur, Nebraska 

25 4/26/2012 Missouri River, Nebraska and Iowa 1125 PLS11-019 23 Decatur, Nebraska 

26 5/3/2012 Missouri River, Nebraska and Iowa 1125 PLS11-019 17 Decatur, Nebraska 

27 5/4/2012 Missouri River, Nebraska and Iowa 1125 PLS11-019 12 Decatur, Nebraska 

28 5/21/2012 Yellowstone River, Montana 51 13 Sidney, Montana 

29 5/22/2012 Yellowstone River, Montana 36 12 Sidney, Montana 

30 5/22/2012 Yellowstone River, Montana 37 9 Sidney, Montana 

31 5/23/2012 Yellowstone River, Montana 272 and 118 17 Sidney, Montana 

32 5/23/2012 Yellowstone River, Montana 36 12 Sidney, Montana 

33 5/21/2012 Yellowstone River, Montana 55 5 Sidney, Montana 

34 5/17/2012 Yellowstone River, Montana 16 6 Sidney, Montana 

35 5/18/2012 Yellowstone River, Montana 92 6 Sidney, Montana 

36 6/9/2012 Yellowstone River, Montana 52 16 Sidney, Montana 

37 6/7/2012 Yellowstone River, Montana 69 12 Sidney, Montana 

38 6/8/2012 Yellowstone River, Montana 69 6 Sidney, Montana 

39 6/12/2012 Yellowstone River, Montana 76 6 Sidney, Montana 

40 6/12, 6/13 Yellowstone River, Montana 230 and 156 20 Sidney, Montana 

1

Radio code in 2011.

2

Radio code in 2012.
Adult Life Stage 51

Telemetry date 

discharge, in cubic 

feet per second 

Discharge 

percentile 

1970–2012 

(upper limit) 

Map date

Map date discharge, 

in cubic feet per 

second

Discharge 

percentile 

1970–2012 

(upper limit) 

Discharge 

difference between 

telemetry and 

mapping 

Percent 

discharge 

diffference

78,800 80 4/22/2010 77,300 70 1,500 2

191,000 100 4/28/2010 191,000 90 -- 0

168,000 100 4/29/2010 168,000 90 -- 0

32,700 70 5/20/2010 36,700 80 4,000 12

35,900 80 5/20/2010 36,700 80 800 2

38,100 80 5/20/2010 36,700 80 1,400 4

35,800 80 5/19/2010 37,500 80 1,700 5

34,800 70 5/19/2010 37,500 80 2,700 8

36,000 80 5/19/2010 37,500 80 1,500 4

34,800 70 5/19/2010 37,500 80 2,700 8

37,500 80 5/26/2010 33,200 70 4,300 11

36,700 80 5/27/2010 32,500 70 4,200 11

125,000 90 5/2/2011 115,000 90 10,000 8

69,300 100 6/4/2011 61,500 100 7,800 11

61,500 100 6/4/2011 61,500 100 -- 0

57,300 100 6/6/2011 57,300 100 -- 0

55,300 100 6/9/2011 57,200 100 1,900 3

53,800 100 6/8/2011 53,800 100 -- 0

57,200 100 6/9/2011 57,200 100 -- 0

26,300 40 4/26/2012 28,700 50 2,400 9

28,300 50 4/26/2012 28,700 50 400 1

39,000 50 4/27/2012 38,200 50 800 2

45,500 70 4/27/2012 38,200 50 7,300 16

25,200 40 5/3/2012 28,800 50 3,600 14

28,700 50 5/3/2012 28,800 50 100 0

28,800 50 5/4/2012 31,300 60 2,500 9

31,300 60 6/1/2012 44,500 90 13,200 42

21,400 90 5/22/2012 21,900 90 500 2

21,900 90 5/24/2012 17,100 90 4,800 22

21,900 90 5/24/2012 17,100 90 4,800 22

19,300 90 5/25/2012 17,600 90 1,700 9

19,300 90 5/29/2012 19,900 90 600 3

21,400 90 5/30/2012 19,100 90 2,300 11

10,800 70 5/31/2012 18,600 90 7,800 72

21,400 90 6/1/2012 17,700 90 3,700 17

39,600 90 6/11/2012 29,400 100 10,200 26

32,300 90 6/12/2012 29,200 100 3,100 10

36,500 90 6/12/2012 29,200 100 7,300 20

29,200 90 6/13/2012 30,000 100 800 3

29,200 90 6/14/2012 25,700 100 3,500 12
52 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

rol15-EMSB0-0040 Delonay Figure 35

Migratory habitat use

EXPLANATION

0

5

10

15

20

-1

0

1

Available habitat

0

5

10

15

20

0

5

10

15

20

-1

0

1

Availability n=31,609

Use n=2,013

0

5

10

15

20

-1

0

1

Frequency, in percent Frequency, in percent Frequency, in percent Frequency, in percent

Depth, in meters

-1

0

1

Velocity, in meters per second

Ivlev’s

selectivity

coefficent

Ivlev’s

selectivity

coefficent

Ivlev’s

selectivity

coefficent

Ivlev’s

selectivity

coefficent

0 2 4 6 8 10 12 0 0.5 1.0 1.5 2.0 2.5

B. Missouri River, Nebraska and Iowa, 2010 and 2012

A. Yellowstone River, Montana, 2011 and 2012

C. Missouri River, Missouri, 2010 and 2011

D. All river segments, 2010–12

Availability n=78,610

Use n=1,300

Availability n=29,012

Use n=283

Availability n=239,222

Use n=3,596

Figure 35. Pallid sturgeon migration habitat availability and use on the Lower Yellowstone and 

Lower Missouri River, 2010–12.
Adult Life Stage 53

frequency with few observations between the initial reproduc-

tive evaluation and the post-spawn evaluation (DeLonay and 

others, 2009; DeLonay and others, 2010; DeLonay and others, 

2012; DeLonay and others, 2014).

Pallid sturgeon spawning has been documented in most 

segments of the Lower Missouri River (fig. 36), including the 

channelized reaches upstream and downstream from the Kan-

sas and Platte Rivers, and in the unchannelized reach down-

stream from Gavins Point Dam. The large apparent differences 

in channel morphology resulting from natural physiographic 

gradients and channel engineering across reaches where 

spawning has occurred in the Lower Missouri River suggest 

that pallid sturgeon can spawn in a wide range of environ-

mental conditions. However, these differences do not indicate 

whether spawning is more or less successful within any par-

ticular reach. Limited reach-scale observations of spawning in 

a highly altered system are not necessarily indicative of broad-

scale patterns of species habitat preference. The distribution of 

sturgeon spawning locations on the landscape is likely shaped 

by habitat characteristics at multiple spatial scales, and may be 

structured by genetics, the distribution or behavior of conspe-

cifics, and an individual’s past experience. Resolving these 

complex relations in the highly altered contemporary river is 

challenging and many more observations may be necessary to 

understand pallid sturgeon spawning dynamics.

The expectation, based on other sturgeon species, is that 

pallid sturgeon aggregation and spawning should occur at a 

few readily identifiable locations, and that spawning would 

occur at the same locations annually with some measure of 

predictability. Although the observations of pallid sturgeon 

spawning are limited, spawning locations appear to be distrib-

uted widely along the Lower Missouri River. Synchronization 

of spawning in sturgeons may affect reproductive success of 

uncommon or geographically dispersed species by ensuring 

that males and females are present at spawning sites at the 

same time, and that aggregations are sufficient to result in 

egg deposition and fertilization. Synchronization of spawning 

can be mediated temporally through environmental variables 

(cues) or spatially through the discrete distribution of suitable 

spawning habitats. Highly altered environments may result in 

changes in physiological readiness to spawn or alterations of 

spawning habitat so that it becomes either too abundant, too 

rare, or of poor suitability. Consequences of altered spawn-

ing synchronicity or insufficient aggregations of sturgeon at 

spawning sites may produce an Allee effect resulting in poor 

reproductive success, altered population genetic structure, and 

hybridization with co-occurring congeneric species, notably 

shovelnose sturgeon.

Eight of the nine probable pallid sturgeon spawning loca-

tions where the spatial extent of spawning was known with 

high confidence (within one RM) based on locations from 

reproductive females (table 2) were mapped on the channel-

ized Lower Missouri River from 2008 to 2012 (DeLonay and 

others, 2009; DeLonay and others, 2012). Spawning locations 

were mapped using boat-based high-resolution hydroacous-

tic tools, including a multibeam echosounder (MBES), an 

Table 5. Migration habitat data summary.[n, number of measurements]

Yellowstone River, 

Montana

Missouri River, 

Nebraska and Iowa

Missouri River, 

Missouri Missouri River total All reaches

Availability

n=131,609

Use

n=2,013

Availability

n=78,610

Use

n=1,300

Availability

n=29,012

Use

n=283

Availability

n=107,622

Use

n=1,584

Availability

n=239,223

Use

n=3,597

Depth, in meters Mean 2.91 2.80 4.50 4.53 7.40 6.64 5.28 4.91 3.98 3.73

Depth-averaged velocity, in 

meters per second

Mean 1.20 1.18 1.16 1.14 1.72 1.27 1.31 1.17 1.25 1.18

Maximum velocity, in meters 

per second

Mean 1.39 1.37 1.38 1.37 2.30 1.78 1.63 1.44 1.49 1.40

Minimum velocity, in meters 

per second

Mean 1.01 0.99 0.91 0.89 1.12 0.77 0.97 0.87 0.99 0.94

Bottom velocity, in meters 

per second

Mean 1.04 1.09 1.10 0.97 1.47 1.09 1.12 1.00 1.11 1.05
54 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

ADCP, and high-resolution global positioning systems (GPS) 

(table 6). One site was downstream from the confluence with 

the Platte River (2012, RM 580.2) on the Nebraska–Iowa 

border in the upstream channelized region of the Lower Missouri River. The remaining seven sites were in the downstream 

channelized section of the Lower Missouri River; two were 

near Kansas City, Missouri (2008, RM 366.4 and 369.5), one 

was near RM 322.2 (2012), and four were near Boonville, 

Missouri (2008–12, RM 230–202) (table 6).

Spawning locations were determined from precise 

acoustic telemetry locations and represent pallid sturgeon 

behavior during the entire course of the spawning activity, 

usually 24–48 hours. Telemetry locations are representative 

of spawning activity that includes repeated bursts of activity, documented in most sites as episodic movements along 

revetted outside bends (DeLonay and others, 2009; DeLonay 

and others, 2010). All telemetry points recorded during the 

time period in which this pattern of behavior was observed 

were used in the analysis of spawning habitat. Maps of depth 

and velocity were created from hydroacoustic data collected 

at spawning locations using previously established methods 

(Reuter and others, 2008; DeLonay and others, 2009; Reuter 

and others, 2009; DeLonay and others, 2012) A bathymetric 

terrain classification was performed using depth and slope 

information (Weiss, 2001; Lundblad and others, 2006; Jacobson and others, 2009b; Reuter and others, 2009). Substrate at 

spawning sites was inferred from sidescan sonar and multibeam data. Sand dunes, revetment, and bedrock are clearly 

visible on sidescan sonar imagery and can be visualized with 

multibeam point cloud data or multibeam data gridded at a 

high resolution (0.10 m) (fig. 37). Revetment slope was measured from multibeam data gridded to 0.10 m at a spawning 

site. Selectivity was calculated using Ivlev’s selectivity coefficient (Manly and others, 2002; Reuter and others, 2009).

Spawning occurred in patches of deep and fast water 

when compared to the ranges of depths and velocities available within the entire channel in a reach (fig. 38, fig. 39, 

table 7). Depths at spawning telemetry locations were greater 

0

600

700

500

800

300

400

200

100

98° 96° 94° 92° 90°

43°

42°

41°

40°

39°

300

Approximate spawning location by year

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

GAVINS

POINT

DAM

KANSAS

MISSOURI

IOWA

NEBRASKA

0 50 100 MILES

0 50 100 KILOMETERS

2007

2008

2009

2010

2011

2012

Base from U.S. Geological Survey digital data, 1999, 1:2,000,000

Universal Transverse Mercator projection

Zone 15

River miles from U.S. Army Corps of Engineers, 1960

Missouri River Basin

EXPLANATION

Missouri River

Figure 36. Spawning locations of pallid sturgeon in the Lower Missouri River, 2007–12.
Table 6. Spawning dates and discharges, 2008–12.[FishID, Fish identification code; ADCP, acoustic Doppler current profiler]

Pallid sturgeon FishID 

and probable 

spawning dates

Date

Missouri River 

mile 

(reach center)

Type of data Nearest streamgage

Discharge, 

in cubic feet 

per second

Streamgage with longer 

flow record

Disc

in cub

per s

PLS08-004 5/4/2008 230 Telemetry Glasgow, Missouri 98,600 Boonville, Missouri 108

5/4/2008–5/5/2008 5/5/2008 Telemetry Glasgow, Missouri 84,400 Boonville, Missouri 91

5/7/2008 Multibeam Glasgow, Missouri 69,700 Boonville, Missouri 73

7/10/2008 ADCP Glasgow, Missouri 81,700 Boonville, Missouri 89

PLS08-009 5/7/2008 369 Telemetry Kansas City, Missouri 54,800 Kansas City, Missouri 54

5/7/2008–5/8/2008 5/8/2008 Telemetry Kansas City, Missouri 56,900 Kansas City, Missouri 56

5/14/2008 Multibeam, ADCP Kansas City, Missouri 63,600 Kansas City, Missouri 63

PLS08-008 5/8/2008 366 Telemetry Kansas City, Missouri 56,900 Kansas City, Missouri 56

5/8/2008–5/9/2008 5/9/2008 Telemetry Kansas City, Missouri 61,800 Kansas City, Missouri 61

5/13/2008 Multibeam, ADCP Kansas City, Missouri 68,600 Kansas City, Missouri 68

PLS09-007 4/25/2009 206 Spawn event Boonville, Missouri 59,400 Boonville, Missouri 59

4/25/2009–4/26/2009 4/26/2009 Multibeam, ADCP Boonville, Missouri 57,800 Boonville, Missouri 57

PLS10-006 4/30/2010 202 Spawn event Boonville, Missouri 135,000 Boonville, Missouri 135

4/31/2010–5/1/2010 5/1/2010 Multibeam, ADCP Boonville, Missouri 112,000 Boonville, Missouri 112

PLS11-008 5/16/2011 216 Telemetry Glasgow, Missouri 123,000 Boonville, Missouri 131

5/17/2011–5/19/2011 5/17/2011 Telemetry Glasgow, Missouri 120,000 Boonville, Missouri 127

5/18/2011 Telemetry Glasgow, Missouri 118,000 Boonville, Missouri 123

5/21/2011 Multibeam Glasgow, Missouri 115,000 Boonville, Missouri 130

5/19/2011 ADCP Glasgow, Missouri 115,000 Boonville, Missouri 119

PLS11-007 3/31/2012 322 Telemetry Waverly, Missouri 62,500 Kansas City, Missouri 66

3/31/2012 4/12/2012 Multibeam Waverly, Missouri 52,700 Kansas City, Missouri 51

4/13/2012 ADCP Waverly, Missouri 51,600 Kansas City, Missouri 50

PLS09-011 4/26/2012 580 Telemetry Nebraska City, Nebraska 38,000 Nebraska City, Nebraska 38

4/26/2012 5/2/12012 Multibeam Nebraska City, Nebraska 40,800 Nebraska City, Nebraska 40

5/1/2012 ADCP Nebraska City, Nebraska 39,700 Nebraska City, Nebraska 39
rol15-EMSB0-0040 Delonay Figure 37

0 5 10 METERS

0 10 20 FEET

EXPLANATION

Depth, in meters

Pallid sturgeon spawning location

1.281.52

Discharge at the U.S. Geological Survey streamgage at Boonville, Missouri, was 112,000 cubic feet per second

Discharge at the U.S. GBoonville, Missouri, w

A B

Bedrock

Bedrock

Sand dunes

Revetment

May 1, 2010;PLS10-006near river mile 202

Figure 37. Examples of high-resolution bathymetry showing A, bedrock and B, revetment and sand dune substrates at probable spawning locat

Missouri River.
Adult Life Stage 57

322

322.5

93°58’20” 93°58’10” 93°58’ 93°57’50” 93°57’40” 93°57’30” 93°57’20”

39°08’40” 39°08’30”

369.5

94°35’30” 94°35’20”

39°08’30” 39°08’20” 39°08’10”

216

216.5

92°56’40” 92°56’30”

39°07’20” 39°07’10” 39°07’ 39°06’50” 39°06’40” 39°06’30”

580

580.5

95°48’50” 95°48’40”

40°53’10” 40°53’ 40°52’50” 40°52’40” 40°52’30”

PLS08-009 spawning 

date May 8, 2008–

May 9, 2008; discharge 

was 59,900–61,8000 

cubic feet per second 

at the U.S. Geological 

Survey streamgage at 

Kansas City, Missouri

PLS11-007 spawning date March 31, 2012; 

discharge was 52,500 cubic feet per second at 

the U.S. Geological Survey streamgage at 

Waverly, Missouri

PLS11-008 spawning 

date May 17, 2011–

May 19, 2011; discharge 

was 118,000–123,0000 

cubic feet per second at

the U.S. Geological Survey 

streamgage at Glasgow, 

Missouri

PLS09-011 spawning 

date April 26, 2012; 

discharge was 38,000 

cubic feet per second 

at the U.S. Geological 

Survey streamgage at 

Nebraska City, 

Nebraska

0 100 200 METERS

0 500 1,000 FEET

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data,

variously dated

River miles from U.S. Army Corps of Engineers, 1960; Sturgeon

locations from U.S. Geological Survey, DeLonay and others, 2012

EXPLANATION

Depth, in meters

0.80

13.14

Sturgeon location—Locations of reproductive female 

pallid sturgeon during probable spawning events

River mile marker—Number is distance upstream 

from the confluence with the Mississippi River, 

in miles

216

A

Figure 38. Bathymetric and acoustic Doppler current profiler velocity maps of reproductive female pallid sturgeon spawning sites 

mapped, 2008–12. A, B, Multibeam depth maps. C, D, Acoustic Doppler current profiler velocity maps.
58 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

230 230.5

92°54’30” 92°54’

39°13’28”

39°13’20”

94°36’ 94°35’30”

39°06’50”

39°06’40”

366

366.5

92°54’30” 92°54’

39°00’50”

39°00’40”

206

206.5

92°50’50” 92°50’25”

38°58’56”

38°58’48”

202

202.5

PLS08-004 spawning dates May 4, 2008–May 5, 2008; 

discharge was 84,400–98,600 cubic feet per second at the 

U.S. Geological Survey streamgage at Glasgow, Missouri

PLS08-008 spawning dates May 7, 2008–May 8, 2008; 

discharge was 54,800–56,900 cubic feet per second at the 

U.S. Geological Survey streamgage at Kansas City, Missouri

PLS09-007 spawning dates April 25, 2009–April 26, 2009; 

discharge was 59,400–57,800 cubic feet per second 

at the U.S. Geological Survey streamgage at 

Boonville, Missouri

PLS10-006 spawning dates April 30, 2010–May 1, 2010; 

discharge was 135,000–112,000 cubic feet per 

second at the U.S. Geological Survey streamgage 

at Boonville, Missouri

0 100 200 METERS

0 500 1,000 FEET

Digital imagery from U.S. Department of 

Agriculture National Agriculture Imagery Program 

digital data, variously dated

River miles from U.S. Army Corps of Engineers, 

1960; Sturgeon locations from U.S. Geological 

Survey, DeLonay and others, 2012

EXPLANATION

Depth, in meters

0.80

13.14

Sturgeon location—Locations of 

reproductive female pallid sturgeon 

during probable spawning events

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

230

B

Figure 38. Bathymetric and acoustic Doppler current profiler velocity maps of reproductive female pallid sturgeon spawning sites 

mapped, 2008–12. A, B, Multibeam depth maps. C, D, Acoustic Doppler current profiler velocity maps.—Continued
Adult Life Stage 59

93°58’10” 93°58’ 93°57’50” 93°57’40” 93°57’30” 93°57’20” 93°57’10”

39°08’40” 39°08’30”

322

322.5

94°35’30” 94°35’20”

39°08’30” 39°08’20” 39°08’10”

369.5

92°56’40” 92°56’30”

39°07’10” 39°07’ 39°06’50” 39°06’40”

216

216.5

95°48’50” 95°48’40”

40°53’10” 40°53’ 40°52’50” 40°52’40” 40°52’30”

580

580.5

PLS11-007 spawning date March 31, 2012; 

discharge was 52,500 cubic feet per second 

at the U.S. Geological Survey streamgage at 

Waverly, Missouri

PLS08-009 

spawning dates 

May 8, 2008–

May 9, 2008;

discharge was 

59,900–61,800 cubic 

feet per second at 

the U.S. Geological 

Survey streamgage 

at Kansas City, 

Missouri

PLS11-008 spawning dates 

May 17, 2011–May 19, 2011; 

discharge was 

118,000–123,000 cubic feet 

per second at the 

U.S. Geological Survey 

streamgage at 

Glasgow, Missouri

PLS09-011 spawning 

date April 26, 2012; 

discharge was 38,000 

cubic feet per second 

at the U.S. Geological 

Survey streamgage 

at Nebraska City, 

Nebraska

Velocity, in meters per second

2.5

0

0 100 200 METERS

0 500 1,000 FEET

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data,

variously dated

River miles from U.S. Army Corps of Engineers, 1960; Sturgeon

locations from U.S. Geological Survey, DeLonay and others, 2012

EXPLANATION

Sturgeon location—Locations of reproductive female 

pallid sturgeon during probable spawning events

River mile marker—Number is distance upstream 

from the confluence with the Mississippi River, 

in miles

216

C

Figure 38. Bathymetric and acoustic Doppler current profiler velocity maps of reproductive female pallid sturgeon spawning sites 

mapped, 2008–12. A, B, Multibeam depth maps. C, D, Acoustic Doppler current profiler velocity maps.—Continued
60 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

92°54’30” 92°54’

39°13’28”

39°13’20” 230 230.5

94°36’ 94°35’30”

39°06’40”

366.5

92°54’30” 92°54’

39°00’50”

39°00’40”

206

206.5

92°50’50” 92°50’25”

38°58’56”

38°58’48”

202

0 100 200 METERS

0 500 1,000 FEET

Digital imagery from U.S. Department of 

Agriculture National Agriculture Imagery Program 

digital data, variously dated

River miles from U.S. Army Corps of Engineers, 

1960; Sturgeon locations from U.S. Geological 

Survey, DeLonay and others, 2012

EXPLANATION

PLS08-004 spawning dates May 4, 2008–May 5, 2008; 

discharge was 84,400–98,600 cubic feet per second at the 

U.S. Geological Survey streamgage at Glasgow, Missouri

PLS09-007 spawning dates April 25, 2009–April 26, 2009; 

discharge was 59,400–57,800 cubic feet per second at 

the U.S. Geological Survey streamgage at 

Boonville, Missouri

PLS10-006 spawning dates April 30, 2010–May 1, 2010; 

discharge was 135,000–112,000 cubic feet per second 

at the U.S. Geological Survey streamgage at 

Boonville, Missouri

PLS08-008 spawning dates May 7, 2008–May 8, 2008; 

discharge was 54,800–56,900 cubic feet per second at the 

U.S. Geological Survey streamgage at Kansas City, Missouri

Velocity, in meters per second

2.5

0

Sturgeon location—Locations of 

reproductive female pallid sturgeon 

during probable spawning events

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

230

D

Figure 38. Bathymetric and acoustic Doppler current profiler velocity maps of reproductive female pallid sturgeon spawning sites 

mapped, 2008–12. A, B, Multibeam depth maps. C, D, Acoustic Doppler current profiler velocity maps.—Continued
rol15-EMSB0-0040 Delonay Figure 39

Frequency, in percent Frequency, in percent

Ivlev’s

selectivity

coefficent

Ivlev’s

selectivity

coefficent

Be

Froude number

0

10203040

Velocity gradient

0

10203040

Depth slope, in degrees

0

102030405060

05

10152025

05

10152025

Depth, in meters

-1

01

Velocity, in meters per second

-1

01

-1

01

-1

01

-1

01

Su

0

20406080

100

-1

01

Terrain classification 

0

20406080

-1

01

0 2 4 6 8 10 12 0 5 10 15 20 25 30 Flat Slope Crest Depression

PA

0 0.5 1.0 1.5 2.0 2.5 0 2 4 6 8 10 0 0.05 0.150.10 0.20 0.300.25 0.35 0.40

Figure 39. Probable pallid sturgeon spawning habitat availability and use at the eight spawning locations mapped on the Lower Missouri River, 2008
Table 7. Summary of water temperature, discharge, substrate, depth, depth-averaged velocity, and turbidity at pallid sturgeon spawning sites in the 2008–12. [FishID, Fish identification code; NTU; nephelometric turbidity units; --, no data] Pallid sturgeon FishID Spawning dates Missouri River mile (reach center) Mean temperature, field measurements, in degrees Celsius Substrate Depth, in meters Depth-a

velo

in meters p

PLS08-004 5/4/2008–5/5/2008 230 15.9 sand, revetment mean 6.65 1.

range 2.18–10.59 0.57–

PLS08-008 5/8/2008–5/9/2008 366 17.8 sand, revetment mean 8.09 1.

range 2.20–9.53 0.58–

PLS08-009 5/7/2008–5/8/2008 369 17.0 sand, revetment mean 6.42 1.

range 5.00–8.11 0.97–

PLS09-007 4/25/2009–4/26/2009 206 17.4 sand, revetment mean 7.66 1.

range 5.21–8.94 0.49–

PLS10-006 4/31/2010–5/1/2010 202 16.6 sand, bedrock, potential gravel mean 8.55 1.

range 3.65–10.27 1.25–

PLS11-008 5/16/2011–5/19/2011 216 17.1 sand, bedrock, potential gravel mean 7.21 1.

range 2.45–10.01 0.46–

PLS11-007 3/31/2012 322 19.4 sand, revetment mean 6.50 1.

range 6.17–6.93 1.27–

PLS09-011 4/26/2012 580 16.8 sand, revetment mean 4.55 1

range 3.53–5.32 0.52–

1Turbidity measurements for PLS08-004 and PLS09-007 are from the U.S. Geological Survey streamgage at Boonville, Missouri, near river mile 197.
Adult Life Stage 63

than those for the entire reach, with a range of 2.2–10.6 m 

between all eight sites and mean depths ranging from 

4.5–8.1 m. Depths for the entire spawning reach at all sites 

ranged from 0.6 to 13.1 m with means between 4.1 and 

6.4 m. Ivlev’s selectivity coefficients suggest selection of 

depths greater than 6 m and avoidance of depths less than 6 m 

(fig. 39). Depth-averaged velocities of fish locations ranged 

between 1.3 and 1.6 m/s with an overall vertically averaged 

mean of 1.44 m/s, somewhat higher than mean velocities for 

the entire reach of 1.3 m/s. (Notably, habitat availability in 

spawning reaches typically is assessed based on habitat that 

can be surveyed with a shallow-draft hydroacoustic vessel in 

relatively uniform outside bends; shallow, slow water on the 

inside bends is not assessed and is not reflected in availability and selection calculations). Velocity selection is positive 

for velocities generally greater than 1.5 m/s and avoidance 

was strongest for depths less than 1 m. Fish selected regions 

with slopes greater than 5 degrees and selection was strong 

in slopes approaching 30 degrees (fig. 39). Regions with 

high velocity gradients, a measure of the spatial change in 

velocity, were positively selected. Nearly all spawning points 

were located in parts of the channel classified as depressions, 

areas of converging flow in or adjacent to the channel thalweg (fig. 39) (Reuter and others, 2009). Spawning sites were 

located near hard substrate in all 8 sites, probable spawning activity occurred near or adjacent to revetment in 6 sites 

(75 percent) and bedrock in 2 sites (25 percent) (table 8, 

fig. 37).

Cross-channel slopes at these spawning sites can be quite 

steep with high surface roughness, which may affect where 

eggs are deposited and may affect relative fertilization and 

hatch success. At a typical site, the mean slope of the revetment from 1 m below the water surface to the toe of the revetment was 50 percent (fig. 40), and ranged from 38–63 percent. 

Bedrock on the bed of the channel (mean depth 7 m) at both 

spawning sites that had natural outcrops was generally rough, 

with 0.3–1 m topographic mounds that could potentially be 

coarse gravels or bedrock knobs (fig. 37).

Although detailed habitat measurements were not made 

in 2012, a probable spawning site was identified on the Yellowstone River based on documented spawning and a prolonged period of fish aggregation. The probable spawning site 

was in the center of a single-threaded reach of the Yellowstone 

River about 6.9 RM upstream of the confluence with the 

Missouri River. It was a roughly elliptical area no more than 

450 m long and less than 100 m wide (see appendix 4). This 

location was also the site of a fish aggregation during the 2011 

spawning season.

Long-Term Patterns of Habitat Use

From 2005 to 2012 CSRP has recorded more than 

8,600 locations from 158 pallid sturgeon along the entire 

811 mile length of the Lower Missouri River, from Gavins 

Point Dam, South Dakota, downstream to the mouth at 

Saint Louis, Missouri, with a few scattered locations in the 

Table 8. Substrate at spawning sites interpreted from sidescan sonar and multibeam bathymetry data, 2010–12.[FishID, Fish identification code; na, not applicable]

Entire reach substrate Fish location substrate Selectivity coefficient

Spawn event dates Percent sand Percent bedrock Percent revetment

Total 

percent 

hard 

substrate

FishID

Number 

of fish 

locations

Percent 

sand

Percent 

bedrock

Percent 

revetment

Total 

percent 

hard 

substrate

Sand Bedrock Revetment Hard substrate

5/4/2008–5/5/2008 97.20 0.00 2.76 2.76 PLS08-004 38 76.30 0.00 23.70 23.70 -0.1 na 0.8 0.8

5/8/2008–5/9/2008 92.73 0.00 7.27 7.27 PLS08-008 13 52.00 0.00 48.00 48.00 -0.3 na 0.7 0.7

5/7/2008–5/8/2008 96.10 0.00 3.90 3.90 PLS08-009 28 63.64 0.00 36.36 36.36 -0.2 na 0.8 0.8

4/25/2009–4/26/2009 97.92 0.00 2.08 2.08 PLS09-007 14 56.00 0.00 44.00 44.00 -0.3 na 0.9 0.9

4/30/2010–5/1/2010 82.48 17.40 0.12 17.52 PLS10-006 32 76.19 19.05 4.76 23.81 -0.0 0.0 1.0 0.2

5/17/2011–5/19/2011 90.05 9.95 0.00 9.95 PLS11-008 24 57.14 42.86 0.00 42.86 -0.2 0.6 0.6

3/31/2012 99.13 0.00 0.87 0.87 PLS11-007 6 54.55 0.00 45.45 45.45 -0.3 na 1.0 1.0

4/26/2012 96.95 0.00 3.05 3.05 PLS09-011 25 49.02 0.00 50.98 50.98 -0.3 na 0.9 0.9

Mean 93.63 3.91 2.47 6.37 142 59.17 10.83 30.00 40.83 -0.23 0.5 0.8 0.7
64 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Mississippi River downstream from the confluence with the 

Missouri River to the mouth of the Ohio River. Analyses 

of pallid sturgeon telemetry locations on the Lower Missouri River resulting from this study are greatly affected by 

the nature of the original, upstream-downstream comparative design and where the fish in the study were captured 

(DeLonay and others, 2009). Early CSRP efforts have focused 

on obtaining adult sturgeon in reproductive condition from 

two, more or less discrete study areas (fig. 3): an upper and 

lower study section within the Lower Missouri River. As a 

result sampling efforts were uneven or intentionally geographically biased in the context of the entire Lower Missouri River. 

Capture efforts also were strongly affected by successful 

broodstock collection efforts near the Platte River, Nebraska. 

Because pallid sturgeon adults are rare on the Lower Missouri 

River, the opportunity to increase implanted individuals in 

the upper study section was favored over an even geographic 

distribution of implanted sturgeon.

Examination of the geographic distribution of location 

data indicates a general pattern of increased location density 

in the areas near tributary confluences. Pallid sturgeon locations from 2007 to 2012 were examined along the length of 

the Lower Missouri River. Locations were normalized and 

standardized using search efforts in 10 RM segments (fig. 41). 

Multiple daily fish locations for individual fish tracked on their 

spawning migrations were not used in the analyses because the 

locations would have biased the sample. The Osage River in 

Missouri and the Platte River in Nebraska appear to strongly 

and positively affect the distribution of tagged pallid sturgeon. 

Smaller tributaries, including the Lamine, Grand, Chariton, 

Nemaha, Kansas, Boyer, and Little Sioux Rivers (fig. 41) also 

may exert some effect on distributions. The value of most 

tributaries to pallid sturgeon and other large river specialists 

has received far less attention than the main stem of the Lower 

Missouri River. Pracheil and others (2013) have suggested 

that larger tributaries may provide many of the same values 

to large river fishes as the main stem, and may be appropriate 

avenues for the conservation and restoration of diversity.

Pallid sturgeon in the Lower Missouri River are capable 

of moving hundreds of miles in a season (DeLonay and others, 

2007); however, multiyear tracking of individuals has demonstrated a propensity for at least some pallid sturgeon to use 

single bends or small habitat patches for many months at a 

time (DeLonay and others, 2012). Patch size in some instances 

was as small as a few tens of meters, and several tagged fish 

were incorrectly designated at times as potentially expired 

fish or expelled tags. Subsequent recapture attempts or sonar 

observation determined that the tagged individuals were in 

good condition (DeLonay and others, 2010).

Telemetered pallid sturgeon of both sexes have been 

documented migrating to the same section of river in the 

Lower Missouri River to spawn with high fidelity and tend to 

return to a previously occupied bend or habitat patch following migration (fig. 42, fig. 43). For example, PLS08-006 is 

a male pallid sturgeon that was captured in nonreproductive 

condition in the spring of 2008. For more than 4 years, from 

2008 to 2011 regardless of his reproductive readiness, PLS08-

006 made repeated upstream migrations in the fall, spending 

winter and spring near RM 640. After the spring spawning 

season, PLS08-006 returned downstream to a location near 

RM 583 (fig. 42). Similar behavior was documented for male 

pallid sturgeon PLS07-020, which has been making annual 

upstream migrations during the fall and spring. PLS07-020 

returns downstream to nearly the same location occupied the 

previous summer near RM 566 after spawning season (fig. 43; 

DeLonay and others, 2012). Telemetry tracking of pallid sturgeon for longer periods will be necessary to assess the level of 

spawning site fidelity and the role of geographic specificity in 

creating and maintaining genetic population structure.

Connectivity and the Importance of Tributaries

Telemetry data have indicated that nonreproductive pallid 

sturgeon use the tributary confluence area and lower segments of large tributaries, such as the Platte and Osage Rivers, 

for extended periods of time. A total of 8 telemetered adult 

rol15-EMSB0-0040 Delonay Figure 40

Sand dunes

2 meters

2 meters

EXPLANATION

Discharge at the U.S. Geological Survey streamgage at

Boonville, Missouri, was 57,800 cubic feet per second 

Revetment rock

0.10-meter gridded multibeam data

at spawning site on April 26, 2009, 

near river mile 206

Spawning location, pallid sturgeon PLS09-007

Depth, in meters

1.5

8.4

Figure 40. Three-dimensional reconstruction created from highresolution multibeam sonar data of habitat used for spawning by 

female pallid sturgeon PLS09-007. Pallid sturgeon in the Lower 

Missouri River spawn on or at the base of steep, rock-covered or 

revetted banks. Nearly all outside bends on the Lower Missouri 

River are revetted and characterized by a narrow transition 

between transporting sand and artificial rock substrate placed for 

bank stabilization.
rol15-EMSB0-0040 Delonay Figure 41

Kansas River

Platte River

Floyd River

Little

Sioux River

Soldier

River

Boyer River

Nishnab o tna

River

Ne maha Riv er

GrandRive

r Charit o

n

R

iver

Missouri River

Osage R

Lamine River

Mississippi River

600

700

500

800

300

400

200

100

Missouri River B

Map area

Base from U.S. Geological Survey digital data, 2003, 1:2,000,000Geographic Coordinate System, North American Datum of 1983

0 15 30 60 MILES River mile

0 30 60 KILOMETERS 15

EXPLANATION

!. River mile marker and number

Mean pallid sturgeon, locations 

per search effort

0.000000 to 0.0562250.056226 to 0.1124500.112451 to 0.1686750.168676 to 0.2249000.224901 to 0.281124

98° 96° 94° 92° 

42°40°

GAVINS 

POINT 

DAM

400

Figure 41. Density of pallid sturgeon telemetry locations in the Lower Missouri River in 2007–12, normalized for search effort.
66 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

rol15-EMSB0-0040 Delonay Figures 42 & 43

EXPLANATION

Missouri River location, in river miles

570

580

590

600

610

620

630

640

650

Missouri River telemetry location

Initial capture, tag implantation and release

Recapture

Date

Missouri River location, in river miles

540

560

580

600

620

640

660

680

700

1/1/08 1/1/09 1/1/10 1/1/11 1/1/12 1/1/13 1/1/14

Date

1/1/07 1/1/08 1/1/09 1/1/10 1/1/11 1/1/12 1/1/13 1/1/14

EXPLANATION

Missouri River telemetry location

Initial capture, tag implantation and release

Recapture

Figure 42. Telemetry locations of male pallid sturgeon PLS08-006 in the Lower Missouri River illustrating 

annual seasonal migrations and a pattern of affinity for specific locations.

Figure 43. Telemetry locations of male pallid sturgeon PLS07-020 in the Lower Missouri River illustrating 

annual seasonal migrations and a pattern of affinity for specific locations.
Adult Life Stage 67

pallid sturgeon, 3 females and 5 males, was located during 

16 search attempts in the Platte River from 2011 through 2012. 

These sturgeon were generally found less than 7 miles up the 

Platte River. For example, female pallid sturgeon PLS08-012 

was initially captured in nonreproductive condition near the 

mouth of the Platte River at Missouri River RM 594.7 on 

March 30, 2008. PLS08-012 was located within 3.5 miles 

upstream or downstream from the mouth of the Platte River 

on 65 occasions from April 2008 through April 2011 (fig. 44). 

Female pallid sturgeon PLS10-029 was found about 33 miles 

up the Platte River, near the confluence of the Platte and Elkhorn Rivers, during May 2011. This female was likely not in 

spawning condition during the spring of 2011. Female PLS10-

029 did, however, return to the Platte River to spawn during 

spring 2012 (see appendix 1).

A total of 8 telemetered pallid sturgeon, 4 females and 

4 males, was located during 28 search attempts in the Osage 

River from 2010 through 2012 (fig. 45). All eight fish were in 

nonreproductive condition at the time. Telemetered pallid sturgeon have been located in the Osage River more than 10 miles 

upstream, near Lock and Dam 1 (fig. 45; about 12 miles 

upstream from the confluence with the Missouri River) and 

have remained in the tributary from spring through early fall. 

Additionally, five pallid sturgeon in nonreproductive condition have continuously occupied the Missouri and Osage River 

confluence area for more than 1 year.

Pallid sturgeon recorded in the confluence areas of large 

tributaries have included potentially wild and hatchery-origin 

individuals, reproductive and nonreproductive adults, and 

migratory and nonmigratory sturgeon. The relative value of 

tributaries to pallid sturgeon recovery is as yet unknown. Tributary confluences and the lower segments of large tributaries 

may provide important habitat for overwintering, aggregation, 

refuge from floods or ice, feeding or reproduction in the highly 

modified Missouri River Basin.

Pallid sturgeon tagged with transmitters by the CSRP 

have been documented to move between the Missouri and 

Mississippi Rivers. The extent of the interconnectedness of 

Missouri River and Mississippi River pallid sturgeon populations is unknown, but the confluence of the Missouri River is 

not a barrier to movement. Telemetry crews located two pallid 

sturgeon tagged in the Lower Missouri River (PLS08-008 

and PLS08-047) in the Middle Mississippi River (DeLonay 

and others, 2010) during 1 week of search effort in July 2009, 

from Mississippi River mile 200 downstream to RM 0 near 

the confluence with the Ohio River. Female pallid sturgeon 

PLS08-008 was initially captured by USGS biologists in the 

Missouri River near RM 183 on March 31, 2008. This female 

continued her upstream migration and spawned in the Missouri River during spring of 2008 near RM 366 (DeLonay and 

others, 2009). PLS08-008 was located by telemetry crews at 

RM 94.5 in the Middle Mississippi River on July 14, 2009, 

about 465 RM downstream from the 2008 spawning location. 

Female pallid sturgeon PLS08-047 also was captured in the 

Missouri River near RM 773 on March 20, 2008, by South 

Dakota Game, Fish and Parks Department and transported to 

Gavins Point National Fish Hatchery for use in the population augmentation program. This female was not successfully 

spawned and was released near her initial capture site on 

July 9, 2008, after being implanted with a telemetry device. 

Shortly after release, PLS08-047 began moving downstream 

and ultimately was recorded near RM 187 in the Middle Mississippi River on July 13, 2009, about 780 RM downstream 

from her initial capture location.

Spawning Periodicity and Readiness to Spawn

It is well known that pallid sturgeon do not spawn on a 

12-month cycle (Dettlaff and others, 1993). Estimates made 

on the length of the pallid sturgeon spawning cycle have 

ranged from 12 to 60 months (Kallemeyn, 1983; Keenlyne 

and Jenkins, 1993; Wildhaber and others, 2007a). The CSRP’s 

multiyear tracking study has provided an opportunity to better 

define spawning periodicity in male and female pallid sturgeon. Spawning periodicity and fecundity are critical parameters in determining potential for pallid sturgeon population 

growth (Wildhaber and others, 2007a; 2011a). Seven male 

fish captured and reproductively assessed multiple times (2–4) 

during CSRP studies were evaluated for spawning cycle length 

based on when they were in and out of reproductive condition. 

All males were captured from the upper study section of the 

Lower Missouri River. One male had a 2-year spawning cycle. 

The remaining fish were determined to have spawning cycles 

longer than 1 year however; insufficient data were available 

to determine whether spawning cycles were completed in 

2 years or longer. Twenty female pallid sturgeon were captured multiple times (2–5) and could be evaluated for spawning cycle length. Most of the fish (n = 8) had spawning cycles 

longer than 2 years, 6 fish had spawning cycles longer than 

1 year and 2 fish had spawning cycles longer than 3 years. 

Four female pallid sturgeon were determined to have cycles of 

exactly 2 years.

The general pattern of hormonal changes that occurs in 

a reproductive female pallid sturgeon from October to May 

was obtained by repeatedly collecting plasma from the same 

female and male pallid sturgeon held for several months at 

Neosho National Fish Hatchery. Hormonal patterns in reproductively cycling sturgeon are predictable and are diagnostic 

for readiness to spawn. Anomalous patterns may be suggestive of environmental factors that disrupt the progression of 

maturation and spawning in hatcheries or natural populations 

(DeLonay and others, 2009). In the female, estradiol and 

testosterone declined from October to February at which time 

testosterone began to increase whereas estradiol continued to 

decline until spawning (fig. 46). In March, 11-ketotestosterone began to increase sharply and continued increasing until 

the female was ready to spawn at which time testosterone 

and 11-ketotestosterone levels dropped (fig. 46). A similar 

hormonal pattern was observed for female pallid sturgeon 

collected from the Lower Missouri River with month-tomonth differences likely attributable to differences in river 

and hatchery water temperatures (fig. 47). A partial hormonal 
95°54’ 95°52’ 95°50’ 95°48’ 

41°04’ 41°02’ 595 596 592 593 594 597 598 Missouri River Bas

Map area Digital Imagery from U.S. Department of Agriculture National Agriculture Imagery Program, digital data, 2012 Universal Transverse Mercator projection, zone 15 0 0.50.25 1 MILE River miles by 

0 0.50.25 1 KILOMETER Platte River EXPLANAT

River mile marker—Numb

from the confluence win miles 300 Telemetry locations for PL

Release location 2008

Figure 44. Telemetry locations of pallid sturgeon PLS08-012 at the confluence of the Platte and Missouri Rivers, Nebraska. Female pallid sturgeo

the Platte River confluence area 65 times between 2008 and 2011 and was not in reproductive condition at any time during the observation period
rol15-EMSB0-0040 Delonay Figure 45

OSAGE LOCK AND DAM 1

Missouri River

Osage River

Maries River

OSAGE COUNTY

COLE COUNTY

CALLAWAY COUNTY

PLS10-025

RM 5.2

PLS10-005

PLS06-015

RM 130

PLS07-011

RM 0.1

PLS07-011

RM 0.3

PLS07-011

RM 129.7

PLS07-011

RM 130.3

PLS06-015

RM 129.8

PLS06-015

RM 129.7 PLS06-015

RM 129.7 PLS06-015 RM 129.7

PLS10-003

RM 130.2

PLS10-003

RM 130.1

PLS07-011

RM 129.8

PLS07-011

RM 130

PLS08-058

PLS10-025

RM 130 PLS07-011

RM 0.1

PLS07-011

RM 0.1

PLS08-058

PLS10-025 PLS10-027

RM 0.2

PLS09-001

RM 0.2

PLS07-011

RM 0.2

PLS08

RM 

OSAGE LOCK AND 

Map area

MISSOURI

ILLINOIS

KANSAS

Imagery from U.S. Department of Agriculture National Agriculture Imagery Program digital data, 2012Universal Transverse Mercator projection, zone 15

A

CD

C

D

A

B

EXPLANATION

Missouri River telemetry locationRelease locationTelemetry locationBoat rampRiver mile

0 0.2 KILOMETER0 0.1 0.2 MILE

0.1

B

0 0.5 1 MILE0 0.5 1 KILOMETER

RM

Figure 45. Telemetry locations of pallid sturgeon in the Osage River and at the confluence of the Osage and Missouri Rivers, Missouri. Locations 

and 7 females) were recorded during 28 search attempts in 2010–12.
70 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Figure 46. Concentrations of reproductive hormones in A, a single female and B, male pallid sturgeon from the 

Lower Missouri River held at Neosho National Fish Hatchery. Female ovulated normally and male produced milt 

normally. Data are from samples collected in 2009 and 2010.

Oct. Dec. Feb. Apr. June 

0

2,000

4,000

6,000

8,000

10,000

12,000

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

0

2,000

4,000

6,000

8,000

10,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

13,000

14,000

Date

Post-spawn

B

A

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

Testosterone, in picograms per milliliter Testosterone, in picograms per milliliter

EXPLANATION

17-beta Estradiol

11-Ketotestosterone

Testosterone
Adult Life Stage 71

rol15-EMSB00-0040 Delonay Figure 47

0

5,000

30,000

25,000

20,000

15,000

10,000

0

8,000

6,000

4,000

2,000

14,000

12,000

10,000

Jan.

(n=5)

Mar.

(n=13)

Apr.

(n=25)

May

(n=4)

Sept.

(n=3)

Oct.

(n=9)

Nov.

(n=2)

0

8,000

6,000

4,000

2,000

12,000

10,000

Estradiol

11-Ketotestosterone 

Testosterone 

Testosterone, in picograms per milliliter

Estradiol, in picograms per milliliter 11-Ketotestosterone, in picograms per milliliter

Jan.

(n=5)

Mar.

(n=12)

Apr.

(n=20)

May

(n=2)

Sept.

(n=2)

Oct.

(n=9)

Nov.

(n=2)

Jan.

(n=5)

Mar.

(n=13)

Apr.

(n=25)

May

(n=4)

Sept.

(n=3)

Oct.

(n=9)

Nov.

(n=2)

50th percentile (median)25th percentile

EXPLANATION

Individual observation above 90th percentile90th percentile75th percentile10th percentileIndividual observation below 10th percentile

Figure 47. Annual changes in estradiol, testosterone, and 11-ketotestosterone measured in reproductive female pallid sturgeon captured in the Lower Missouri River from 

2005 to 2012. Number of samples is in parenthesis.
72 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

pattern could be obtained from one captive male (fig. 46), and 

a slightly more complete annual pattern obtained from a male 

pallid sturgeon from the Lower Missouri River (albeit missing 

data from the fall before spawning) revealed similar patterns 

(fig. 48). Both patterns are consistent with low and decreasing 

concentrations of estradiol and low levels of the androgens 

that increase as the fish approaches spawning.

The general pattern of hormonal changes that occurs in 

nonreproductive pallid sturgeon from October to April was 

obtained by repeatedly collecting plasma from many individuals held for several months at Neosho National Fish Hatchery. 

Immediately after spawning, all hormones are either declining or at their lowest concentrations in both sexes. During the 

several months before the next spawning, estradiol and testosterone in females, and testosterone and 11-ketotestosterone 

in males increase (fig. 49). Monthly hormonal concentrations 

measured in pallid sturgeon sampled upon capture from the 

Lower Missouri River follow similar trends. However, field 

data indicate seasonal fluctuations and the higher monthly 

variability reflects the differences in degree of gonadal development (recrudescence) among nonreproductive fish (fig. 50, 

fig. 51).

Twenty female pallid sturgeon, tracked during all or a 

portion of their reproductive cycle, were subsequently recaptured and assessed for evidence of spawning at some date after 

expected spawning. Of these, only two individuals were classified as not having spawned; the ovaries of these two females 

were at varying stages of oocyte follicle resorption. Hormonal 

patterns of hatchery-held pallid sturgeon that did not ovulate 

after induction or that had identifiable oocyte atresia differed 

from similar fish that successfully ovulated (fig. 52). Females 

that did not ovulate displayed a steep drop in testosterone 

months before the projected spawning date followed by an 

increase in testosterone closer to the expected spawning date 

(fig. 52). Females with atretic oocytes appeared to experience 

an earlier decline in testosterone and a delay in the increase of 

11-ketotestosterone (fig. 52).

Reproductive readiness in our tracking studies has been 

determined using the polarization index (PI) and results of the 

progesterone assay (DeLonay and others, 2009). Polarization 

data have been collected for 95 pallid sturgeon since 2005; 

however, data were sufficient to evaluate annual temporal 

trends only for 2010, 2011, and 2013 (fig. 53). Previously, 

using shovelnose sturgeon, we have determined that water 

temperature more closely associates with reproductive readiness than discharge parameters, for example total discharge, 

timing of peaks, and rate of change (DeLonay and others, 

2009; Papoulias and others, 2011). This relation continues to 

be supported by the pallid sturgeon data (fig. 54, fig. 55).

Contaminants in Reproductive Ecology of Pallid 

Sturgeon

Chemical contamination of the Missouri River has been 

identified as a potential threat to the reproductive success of 

adult pallid sturgeon and the survival of early life stages. Longevity, high lipid content, use of benthic habitat, piscivorous 

feeding behavior, and multiyear reproductive cycles are characteristics that make the pallid sturgeon particularly vulnerable to some contaminants. Health departments of the states 

bordering the Missouri River regularly analyze fishes from the 

Missouri River and its tributaries for chemicals that bioaccumulate in fish tissues in order to protect people from consuming contaminated flesh and eggs. Concentrations of chlordane, 

DDT, and mercury have decreased for the last two decades, as 

expected for these legacy chemicals, following similar trends 

for these compounds nationally (U.S. Environmental Protection Agency, 2013). Few additional studies have measured 

contaminants in Missouri River water, sediments, and biota; 

even fewer studies have been done to determine whether 

legacy chemicals or modern, less persistent chemicals, are 

affecting the health of Missouri River fish populations.

Ruelle and Keenlyne (1993) first presented data indicating that pallid sturgeon had elevated levels of heavy metals, 

PCBs, and some banned pesticides, yet few pallid sturgeon tissues have been examined recently (2015) because of the rarity 

of the fish. However, analysis of shovelnose sturgeon tissues 

in the intervening years provides an important record from 

which pallid sturgeon exposure can be inferred. The trends for 

the Lower Missouri River and generally throughout the range 

of the pallid sturgeon indicate that older industrial chemicals 

and pesticides such as polychlorinated biphenyls (PCBs), 

dioxins, chlordane, DDT, and metabolites have decreased. 

However, some contaminants remain at elevated concentrations at specific locations (Mike Mckee, Missouri Department of Conservation, oral commun., 2014; Blevins, 2011) 

reflecting the decline in water and sediment concentrations 

(Coffey and others, 2000; Petty and others, 2004; Echols and 

others, 2008; Blevins, 2011). Nevertheless, the biological and 

ecological characteristics of pallid sturgeon (benthic, piscivorous, long-lived, multiyear reproductive cycles) increase 

their chances of exposure even to low concentrations of these 

legacy compounds that easily bioaccumulate in lipid-rich tissues of the sturgeon. Effects on eggs and early life stages of 

offspring by way of maternal exposure are likely more a cause 

for concern for the legacy chemicals than direct effects on 

adult pallid sturgeon as Buckler (2011b) demonstrated.

Contemporary contaminants of greatest concern for 

affecting health of pallid sturgeon include the flame retardants 

(for example, PBDEs, polybrominated diphenyl ethers), hormonally active compounds reported in wastewaters, and the 

high-volume use pesticides such as glyphosate and atrazine. 

These chemicals and others, collectively referred to as endocrine disrupting chemicals (EDCs), have known effects on 

the vertebrate endocrine system that lead to effects on reproduction, growth, and behavior (Mills and Chichester, 2005). 

Except for the PBDEs, endocrine disruptors do not readily bioaccumulate in tissue and have shorter environmental half-lives 

making them more difficult to measure in water, sediment, and 

tissue. Exposure to EDCs, therefore, is commonly evaluated 

based on bioindicators. Bioindicators for fish, including the 
rol15-EMSB00-0040 Delonay Figure 48

Apr.

(n=26)

May

(n=3)

June

(n=1)

Jan.

(n=1)

Mar.

(n=12)

Apr.

(n=26)

Jan.

(n=1)

Mar.

(n=12)

Apr.

(n=26)

May

(n=3)

June

(n=1)

Jan.

(n=1)

Mar.

(n=12)

11-Ketotestosterone 

Estradiol Testosterone 

Testosterone, in picograms per milliliter

Estradiol, in picograms per milliliter 11-Ketotestosterone, in picograms per milliliter 50th percentile (median) 25th percentile EXPLANATION 10th percentile Individual observation below 10t

Individual observation above 90t90th percentile 75th percentile 0 10,000 20,000 30,000 40,0000 200 400 600

800

1,000

0

5,000

10,000

15,000

20,000

25,000

30,000

Figure 48. Annual changes in estradiol, testosterone, and 11-ketotestosterone measured in reproductive male pallid sturgeon captured in the Lowe

to 2012. Number of samples is in parenthesis.
74 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Figure 49. Mean reproductive hormone concentrations in A, noncycling adult female and B, male pallid sturgeon 

held at Neosho National Fish Hatchery. Data are from samples collected in 2009 and 2010.

June 

9,500

10,000

10,500

11,000

11,500

12,000

12,500

13,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Date

Oct. Dec. Feb. Apr. 

B

EXPLANATION

17-beta Estradiol

11-Ketotestosterone

Testosterone

A

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

Testosterone, in picograms per milliliter Testosterone, in picograms per milliliter

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0

500

1,000

1,500

2,000

2,500
rol15-EMSB00-0040 Delonay Figure 50

Oct.

(n=15)

Nov.

(n=5)

Jan.

(n=4)

Mar.

(n=28)

Apr.

(n=45)

May

(n=7)

June

(n=7)

Sept.

(n=19)

11-Ketotestosterone 

Estradiol Testosterone 

Testosterone, in picograms per milliliter

Estradiol, in picograms per milliliter 11-Ketotestosterone, in picograms per milliliter 50th percentile (median) 25th percentile EXPLANATION 10th percentile Individual observation below 10

Individual observation above 9090th percentile 75th percentile 0 200 400 600 800 1,000 1,200

1,400

1,600

1,800

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

Oct.

(n=15)

Nov.

(n=19)

May

(n=7)

June

(n=7)

Sept.

(n=19)

Oct.

(n=12)

Nov.

(n=4)

Jan.

(n=4)

Mar.

(n=25)

Apr.

(n=37)

May

(n=5)

June

(n=6)

Sept.

(n=12)

Figure 50. Annual changes in estradiol, testosterone, and 11-ketotestosterone measured in nonreproductive female pallid sturgeon captured in the 

from 2005 to 2012. Number of samples is in parenthesis.
rol15-EMSB00-0040 Delonay Figure 51

Oct.

(n=5)

Jan.

(n=2)

Mar.

(n=15)

Apr.

(n=29)

May

(n=6)

June

(n=15)

Sept.

(n=12)

Ketotestosterone 

Estradiol Testosterone 

Testosterone, in picograms per milliliter

Estradiol, in picograms per milliliter 11-Ketotestosterone, in picograms per milliliter 50th percentile (median) 25th percentile EXPLANATION 10th percentile Individual observation below 10

Individual observation above 9090th percentile 75th percentile 0 2,000 4,000 6,000 8,000

10,000

12,000

0

200

400

600

800

1,000

1,200

0

5,000

10,000

15,000

20,000

25,000

Oct.

(n=5)

Jan

(n=2

May

(n=6)

June

(n=15)

Sept.

(n=12)

Oct.

(n=4)

Jan.

(n=2)

Mar.

(n=15)

Apr.

(n=27)

May

(n=6)

June

(n=15)

Sept.

(n=12)

Figure 51. Annual changes in estradiol, testosterone, and 11-ketotestosterone measured in nonreproductive male pallid sturgeon captured in the L

2005 to 2012. Number of samples is in parenthesis.
Adult Life Stage 77

Figure 52. Concentrations of reproductive hormones in A, a non-ovulating and B, an atretic female pallid 

sturgeon from the Missouri River, held at the Neosho National Fish Hatchery. Data are from samples collected in 

2009 and 2010.

June 

Date

Oct. Dec. Feb. Apr. 

B

EXPLANATION

17-beta Estradiol

11-Ketotestosterone

Testosterone

A

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

17-beta Estradiol, in picograms per milliliter

11-Ketotestosterone, in picograms per milliliter

Testosterone, in picograms per milliliter Testosterone, in picograms per milliliter

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May 

0

2,000

4,000

6,000

8,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

22,000

Post-spawn Post-spawn
rol15-EMSB00-0040 Delonay Figure 53

3/1/11 3/15/11 3/29/11 4/12/11 4/26/11 5/10/11 5/24/11 

0

0.05

0.10

0.15

0.20

0.25

0.30

3/1/10 3/15/10 3/29/10 4/12/10 4/26/10 5/10/10 5/24/10 6/7/10 

0

0.05

0.10

0.15

0.20

0.25

0.30

0

5

10

15

20

25

30

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

0

5

10

15

20

25

10,000

3/1/13 3/15/13 3/29/13 4/12/13 4/26/13 5/10/13 5/24/13 6/7/13 

15,000

20,000

25,000

30,000

35,000

40,000

45,000

0.00

0.05

0.10

0.15

0.20

Polarization index

Polarization index 

Discharge, in cubic feet per second

Temperature, in degrees Celsuis

Polarization index

Discharge, in cubic feet per second

Temperature, in degrees Celsuis

Date Date

Date

Polarization indexDischargeTemperatureSpawning first detected

EXPLANATION

Figure 53. Relation between reproductive readiness in female pallid sturgeon from the Missouri River, hydrograph, and temperature for 3 years 20

Reproductive readiness is indicated by the polarization index (PI). A lower PI value indicates the fish is closer to spawning. Discharge and temperathe U.S. Geological Survey streamgage at Decatur, Nebraska.
Adult Life Stage 79

2011

Feb. Mar. Apr. May June 

2011

Feb. Mar. Apr. May June 

Discharge, in cubic feet per second

20,000

40,000

60,000

80,000

100,000

120,000

Temperature, in degrees Celsius

0

5

10

15

20

25

11-Ketotestosterone : 17-beta Estradiol ratio

Discharge, in cubic feet per second

Temperature, in degrees Celsius

11-Ketotestosterone : 17-beta Estradiol ratio

0

200

250

25

180

Discharge

Temperature

Spawning first detected

Fish had spawned

11-Ketotestosterone : 17-beta Estradiol ratio

EXPLANATION

25,000

30,000

35,000

40,000

45,000

50,000

0

5

10

15

20

25

0

2

4

6

8

10

12

14

16

18

20

Discharge

Temperature

Spawning first detected

Fish had spawned

11-Ketotestosterone : 17-beta Estradiol ratio

EXPLANATION

No data

Figure 55. Readiness to spawn in female Missouri River pallid sturgeon, as the ratio of 11-ketotestosterone:17-beta estradiol

(11KT:E2), to discharge and temperature in 2012. Discharge and temperature from data collected at the USGS Decatur, 

Nebraska streamgage.

Figure 54. Readiness to spawn in female Missouri River pallid sturgeon, as the ratio of 11-ketotestosterone:17-beta 

estradiol (11KT:E2), to discharge and temperature in 2011. Discharge and temperature from data collected at the USGS 

Decatur, Nebraska streamgage.
80 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

pallid and shovelnose sturgeon, in the Lower Missouri River 

and the Mississippi River and their tributaries consist of measuring vitellogenin in immature and male fish and identifying 

animals with intersex gonads and males with abnormal plasma 

estrogen:androgen levels (Harshbarger and others, 2000; 

Papoulias and others, 2003; Koch and others, 2006; Papoulias and others, 2006; Schwarz and others, 2006; Colombo 

and others, 2007; Papoulias and others, 2009b). The study 

of pallid sturgeon reproductive behavior and response to the 

contemporary Missouri River flow regime also has provided 

an opportunity to evaluate plasma hormone concentrations and 

to examine gonad development (Wildhaber and others, 2005; 

Papoulias and others, 2009b). However, no controlled laboratory studies that investigate the links between exposure to 

endocrine disruptors and effects, in particular population-level 

effects, on pallid and shovelnose sturgeon exist.

Biomarkers measured to evaluate exposure to estrogenic 

chemicals typically include vitellogenin protein, plasma 

estrogen:testosterone ratio, and the presence of intersex 

gonads. Current evidence for endocrine disruption affecting 

pallid sturgeon rests on the incidence and severity of intersex 

gonads found in this species and closely related shovelnose 

sturgeon. Vitellogenin, a yolk protein precursor, is typically 

elevated in male and juvenile fish exposed to estrogens (Miller 

and others, 2007). Vitellogenin levels in male pallid sturgeon 

from the Missouri River are in the normal range and are three 

to four orders of magnitude lower than females (fig. 56). 

Estrogen:androgen ratios also measure within the normal 

range for males (data not shown) and there is only slight evidence of lowered sperm quality in fish captured from the river 

compared with hatchery-captive fish (table 9). Nevertheless, 

intersex gonads have been identified in two pallid sturgeon 

and occurs at a rate as high as 24 percent in male shovelnose 

sturgeon in some locations in the Lower Missouri River 

(Papoulias and others, 2007; Papoulias and others, 2009a). The 

detected incidence of intersex in pallid sturgeon is necessarily 

low because few animals are opened and examined. Additional 

gonadal abnormalities have been observed for pallid and shovelnose sturgeon including testicular dysgenesis and teratomas 

(2 in shovelnose sturgeon and 1 in pallid sturgeon), but only 

the former is a known estrogenic effect.

Population Augmentation

Evidence indicates that hatchery-origin pallid sturgeon are 

surviving, growing, reaching sexual maturity, and spawning 

in the Lower Missouri River (DeLonay and others, 2009). In 

all study sections of the Missouri River, hatchery-origin pallid 

sturgeon will soon out-number wild adults in the population. 

To date the CSRP has recorded the spawning locations of 

six female hatchery-origin pallid sturgeon in the lower study 

section of the Lower Missouri River. No known hatcheryorigin pallid sturgeon have been documented spawning in the 

upper study section to date (2015). Although documentation 

of spawning of hatchery-origin individuals is an important 

measure of success for the pallid sturgeon recovery program, 

uncertainties remain about the viability of hatchery-origin individuals. It is unknown whether or not hatchery fish respond to 

the same environmental cues as wild fish and whether hatchery 

fish have similar spawning success, in terms of viable fertilized 

eggs and larvae. Studies of reproductive success of steelhead 

trout (Araki and others, 2007) and coho salmon (Theriault 

and others, 2011), for example, have concluded that hatcheryorigin progeny have lower reproductive success than their wild 

counterparts. Studies by Sloss and others (2009) documented 

evidence of hatchery-selection and a reduction of genetic 

diversity in paddlefish. More information is needed to evaluate the relative contribution of hatchery-origin pallid sturgeon 

to reproduction, recruitment, and population recovery in the 

Lower Missouri River. Additional movement and spawning 

rol15-EMSB00-0040 Delonay Figure 56

Females

(n=6)

Males,

river mile<300

(n=4)

Males,

river mile>500

(n=15)

Vitellogenin, in picograms per milliliter

0

100,000

200,000

300,000

400,000

500,000

600,000

200

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 10th percentile

Individual observation above 90th percentile

90th percentile

75th percentile

Figure 56. Plasma vitellogenin concentrations in male pallid 

sturgeon from below river mile 300 and above river mile 500 in 

the Missouri River compared to plasma vitellogenin in female 

pallid sturgeon. Samples were collected during 2012. Number of 

samples is in parenthesis.
Adult Life Stage 81

data for wild adult fish are needed to refine the understanding 

of the genetic population structure of pallid sturgeon (Schrey 

and Heist, 2007). Movement and spawning data for adult 

hatchery-origin pallid sturgeon may provide managers with 

information needed to balance the risk of population augmenta-

tion in the Missouri River to locally adapted populations in the 

Middle and Lower Mississippi River.

Flow Regime Management

Spawning migration data have not indicated consistent 

linkages to discharge conditions or flow pulses in the Lower 

Missouri River. Lack of clear linkages does not indicate that 

discharge is not an important variable for sturgeon reproduc-

tion, but it does indicate that discharge in the regulated Lower 

Missouri River does not exert an overwhelming control or may 

interact with other variables in complex ways (DeLonay and 

others, 2012). Migration patterns indicate linkages to watertemperature fluctuations that seem to fall into two categories 

(DeLonay and others, 2009; 2010b). The first is a temperature 

threshold for spawning at 16–18 ̊C. Water temperatures above 

this threshold seem to be necessary for spawning of pallid stur-

geon, but temperature alone is insufficient to insure spawning 

because other requirements (for example, presence of mates, 

substrate, local flow conditions) may not be satisfied.

The other effect is a notable linkage between changes in 

water temperature and migration rate or direction (DeLonay 

and others, 2010). Sudden decline in water temperature during 

the generally increasing temperatures of the spring spawning 

season may delay or disrupt spawning migrations (DeLonay 

and others, 2009; 2010b; 2012a). The disrupted migration 

patterns of reproductively ready female pallid sturgeon may 

translate into reduced spawning success if eggs are not ovu-

lated or are deposited in sub-optimal habitats under inappro-

priate environmental temperatures or flows.

On the Upper Missouri River, the Yellowstone River is 

significant in that it has an intact natural hydrograph with a 

natural turbidity regime. In most years, pallid sturgeon move 

up the Yellowstone River from the Missouri River in response 

to increasing temperatures and flows (Fuller and others, 2008; 

DeLonay and others, 2014). Annually the disproportionate 

percentage of adults using the Yellowstone River compared 

to the Missouri River above the confluence suggests that the 

pallid sturgeon either prefer the warmer, more turbid Yel-

lowstone River or are avoiding the cooler, clearer Missouri 

River. During extreme flow events in 2011, pallid sturgeon use 

changed substantially, and a larger percentage of adults moved 

up the Missouri River below Fort Peck Dam (DeLonay and 

others, 2014). It is unclear what the relative role of discharge, 

temperature, or tributary flows from the Milk River may have 

played in 2011 that ultimately changed sturgeon distribution 

and resulted in the first documented successful spawning in 

the Missouri River. It is clear from study results that pallid 

sturgeon are capable of responding to environmental variables 

on the landscape and retain the flexibility to use spawning 

Table 9.

areas in both rivers when conditions are suitable.

Measures of sperm quality for milt collected from captive and wild pallid sturgeon during 2011.

[See text for specific information about methods for each measurement. A Kruskal-Wallis rank test was used to test for differences in wild and captive fish (*) indicates a significant difference between groups occurred at p<0.05]

Source Number Osmolarity* Motility (percent) Duration, (seconds) Live (percent) Apoptotic (percent) Live Apoptotic (percent) Mitochondrial function (percent)* DNA integrity (percent) Total motility (percent) Progressive motility (percent)* Sperm counts Adenosine triphosphate

Wild 2011 13 85 93 166 96 4 1 98 5 77 73 95,700,000 2.3

Captive 2011 7 93 81 416 94 6 2 94 4 59 45 59,920,000 1.6
82 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Channel Re-Engineering

There is potential for reproductive adult life stage processes to be affected by channel re-engineering that would 

improve spawning habitats or migration pathways. All spawning locations documented in Lower Missouri River study 

sections were on outside revetted bends, over or adjacent to 

coarse substrate and bedrock. Water depths were generally the 

deepest available in the reach with relatively fast and turbulent 

flow (DeLonay and others, 2009; 2010b; 2012a). These areas 

are relatively insensitive to changes in discharge (Jacobson 

and others, 2009b) and may be less sensitive to temperature 

variations than other areas with suitable coarse substrate but 

with shallow depth or away from the main flow of the river 

(DeLonay and others, 2010).

Most sturgeon species, including lake sturgeon, gulf 

sturgeon (Acipenser oxyrinchus desotoi), white sturgeon 

(Acipenser transmontanus), Chinese sturgeon (Acipenser sinensis), and Amur sturgeon (Acipenser schrenckii) spawn in rivers 

on a variety of generally hard substrates ranging from gravel 

mantled bedrock (Sulak and Clugston, 1998; Fox and others, 

2000) to gravels, cobbles, and boulders (Parsley and others, 

1993; Krykhtin and Svirskii, 1997; Perrin and others, 2003; Du 

and others, 2011), sand (Paragamian, 2012), and including artificial substrates such as cinders (Manny and Kennedy, 2002), 

wooden pilings, and artificial gravels (Bruch and Binkowski, 

2002; Johnson and others, 2006b). On the channelized Lower 

Missouri River the bank slope on the outside of every bend has 

been covered in bank revetment made up primarily of angular limestone and dolomite boulders similar to those found at 

six pallid sturgeon spawning locations. Additional sources of 

hard substrate on the channelized Lower Missouri River occur 

in discontinuous patches including natural bedrock outcrops, 

natural gravel and cobble outcrops of glacial origin, deposits 

of re-worked engineered material, and in tributaries draining 

higher-relief terrain, such as the Ozark Plateau in Missouri 

(Laustrup and others, 2007). Bedrock exposures are densest in places along the Missouri River adjacent to bluffs, and 

particularly in regions with narrower valleys such as the lower 

250 miles of the Missouri River in Missouri (Laustrup and others, 2007) (fig. 3).

The historic unchannelized Missouri River was a 

dynamic, braided, sand-bedded and shifting river system. 

Locations of persistent pre-channelization bedrock outcrops 

are unknown. However, there is a greater probability that 

coarse substrates occurred on the pre-channelization Missouri 

River in regions with narrow valleys, glacial deposits, and 

with coarse-bedded tributary inputs. Outside revetted bends 

are now a common habitat type in the channelized Missouri 

River (Laustrup and others, 2007) and may not be a limiting 

factor for spawning. Revetment is a relatively new addition to the Missouri River landscape. Consequently, revetted bends may be the best available spawning habitat, rather 

than optimal habitat. As such, research needs to address how 

well embryos deposited on revetted bends survive and hatch 

(DeLonay and others, 2012).

Comparative observations in the Yellowstone River 

indicate that more natural spawning habitat may consist of 

patches of gravel on relatively flat slopes in the center of the 

channel and surrounded by actively transporting sand dunes. If 

subsequent research confirms that the Yellowstone River sites 

provide greater spawning success than Lower Missouri River 

spawning sites, measurements of Yellowstone River spawning sites may provide useful design parameters for restoring 

spawning habitat in the Lower Missouri River. Possibly, fewer 

high-quality habitat sites would serve to attract pallid sturgeon 

away from abundant, less productive revetment sites and result 

in a net increase in spawning success. However, much needs to 

be known about the relation between arrangement of spawning 

habitat and free-embryo dispersal and recruitment success.

Migration pathways could be managed to decrease 

energy expenditures in upstream migrations by re-engineering 

the channel to increase areas of slower velocity. Present (2015) 

information, however, does not indicate that upstream migration by adult pallid sturgeon is substantially impeded. In the 

more natural channel segments in the Yellowstone River and 

the upper segment of the Lower Missouri River, migrating 

adults use available depths and velocities in nearly the same 

proportion that they are available, showing little selection. In 

the lower segment of the Lower Missouri River, migrating 

adults clearly avoid the fastest and deepest parts of the navigation channel, yet they select pathways with velocities similar 

to those used on the Yellowstone River and that minimize total 

energy expenditure (McElroy and others, 2012). Therefore, 

although these observations indicate that the channelization 

has diminished some pathways, reproductive sturgeon can 

still find functional pathways within the channel as presently 

(2015) engineered.

Embryo Life Stage

An embryo is a developing fish still within the chorion 

(egg membrane). The embryo life stage lasts from fertilization 

to hatch, usually about 5–8 days, depending on temperature. 

Because of the embryo’s small size and the location of their 

habitat at substantial depth in the Missouri River, most of 

what is known about habitat requirements is extrapolated from 

laboratory measurements.

Habitat Requirements for Embryos

Water hardened pallid sturgeon embryos are approximately 3.0 mm in diameter and weigh 16 mg. Naturally 

spawned pallid sturgeon eggs become sticky or adhesive 

1 to 3 minutes after fertilization (Dettlaff and others, 1993) 

and presumably fall through the water column to affix to a 

solid substrate such as rock. Experiments in 2010 (DeLonay 

and others, 2012) indicated that adhesive embryos falling at 

an average rate of 1.98 m/sec through 2.4 m of water under 

turbid conditions (97–689 Nephelometric Turbidity Units, 
Embryo Life Stage 83

NTUs) did not adhere to substrate at the bottom of the water 

column because fine silt particles had coated the embryos 

during their descent. In contrast, embryos that fell through 

clear water did adhere. Qualitative observations indicated 

that eggs lost their ability to adhere within 0.3 to 0.6 m below 

the surface after release into the turbid water suggesting that 

pallid sturgeon females must ovulate in close proximity to the 

substrate if embryos are to attach and develop while adhered 

to a solid substrate. Turbidity on the Lower Missouri River has 

decreased considerably from pre-dam levels (Blevins, 2006) 

and has been reported to vary within 2 to 3 orders of magnitude with increasing discharge (Blevins, 2011). Turbidity 

measurements near two spawning sites during spawning activity on the lower Missouri River were high, but not excessively 

high (210–390 and 50–68 NTUs) given the magnitude of historic measurements and the variability in turbidity seen in the 

contemporary river (2015) (Blevins, 2006) (fig. 26, table 7). 

The relative importance of turbidity for the deposition, fertilization and hatch of pallid sturgeon embryos is unknown.

Observations of hatching pallid embryos in an artificial stream at the Columbia Environmental Research Center 

(CERC) in 2012 indicated that the embryo is very active as 

hatching nears. The chorion became thinner over several hours 

as enzymes released from the embryo’s hatching gland softened the chorion membrane (Dettlaff and others, 1993). In the 

CERC 2012 experiments, adherent embryos were manually 

placed on a rock cobble substrate arranged in a simple monolayer formation. When the embryo broke out of the chorion, 

the moving water forced it to the bottom of the tank where it 

was swept away and into the current.

Fertilization rate, time to hatch, and percent of embryos 

that hatch are known only from laboratory studies and 

hatchery propagation efforts. Four pallid sturgeon have been 

spawned at the CERC using hormone induction followed 

by hand stripping of ovulated eggs. Fertilization rates for 

these fish ranged from 91 percent to 98 percent, with a mean 

and median of 94 percent. In comparison, 29 shovelnose 

sturgeon have been spawned with fertilization rates ranging 

from 44 percent to 98 percent, mean = 83 percent, median 

= 85 percent, and mode = 92 percent. Development times 

did not differ substantially between species. A general guide 

compiled from embryo development and hatch times from 

both sturgeon species reared at five temperatures in studies at 

the CERC are reported in table 10. As temperature increases, 

development accelerates and time to hatch is reduced. Webb 

and others (2007) documented a similar trend with increasing temperatures; however, time to various developmental 

milestones in their studies was slightly shorter, albeit time 

to hatching was slightly longer, than in trials done at similar 

temperatures in CERC studies. Hatching generally occurs over 

2 days. Percent hatch of pallid sturgeon embryos at the CERC 

ranged from 80–90 percent at approximately 18 o

C (Buckler, 

2011). Webb and others (2007) reported similar rates of hatch 

success between 16 and 20 oC, whereas at 24 oC hatch was 

significantly less but still greater than 75 percent.

Six probable spawning locations mapped with high-resolution multibeam and sidescan sonar on the Lower Missouri 

River were on or near bank revetment on the outside bend of 

the channel near the thalweg with depths ranging from 2.2 

to 10.6 m and mean water-column velocities ranging from 

0.49 to 2.36 m/s (fig. 40, table 7). The availability of clean 

spawning substrate (suitable for egg adhesion) and the amount 

of interstitial spaces between rocks in bank revetment are 

unknown. Probable pallid sturgeon spawning also has been 

documented in two locations on or adjacent to natural dolomite bedrock outcrops on the Missouri River (fig. 7, table 7). 

Bedrock at these sites is exposed on the channel banks, as well 

as at depth, and has a rough topography with 0.3 to 1 m of 

relief that may indicate gravel deposits or bedrock knobs on 

the bed of the river. Due to the logistical and safety challenges 

of working in deep, fast, and muddy water, direct observations 

of spawning substrate and embryo release during a spawning 

event have not been made, and embryos have not been collected from the field. A probable spawning site on the Yellowstone River near RM 4 to 7 (Fuller and others, 2008) presents 

an opportunity to evaluate spawning habitat in a less-altered 

system; however, spawning substrates at this site have not yet 

been directly measured. Preliminary analysis of sidescan sonar 

imagery indicates that this site is likely composed of mixed 

gravel, cobble, and sand.

Predation has been demonstrated to occur on white 

sturgeon embryos on the Columbia River (Miller and Beckman, 1996), Chinese sturgeon embryos on the Yangtze River 

in China (Yu and others, 2002; Zhang and others, 2011) and 

is a common fate for lake sturgeon embryos (Caroffino and 

others, 2010b). Although many species of fish native to the 

Missouri and Yellowstone Rivers eat embryos, it is unknown 

whether predation is a threat to pallid sturgeon embryos and 

the pallid sturgeon populations on the Missouri and Yellowstone Rivers. Interstitial spaces and high turbidity may 

provide cover for embryos from opportunistic feeders, and 

the high velocities and deep water near assumed embryo 

deposition sites on bank revetment and bedrock on the Lower 

Missouri River may present a difficult environment for some 

predator fish to feed.

Flow Regime Management

It has been hypothesized that one of the functions of 

spring pulses on the Missouri River was to “condition” 

spawning substrate by cleaning it of fine sediment to allow 

embryos to adhere (U.S. Fish and Wildlife Service, 2003; 

Jacobson and Galat, 2008). Sediment transport and substantial channel change occur on the Lower Missouri River for a 

wide range of discharges including managed and natural flow 

events (Elliott and others, 2009). Flow pulses on the scale of 

the spring rises that occurred on the Missouri River in 2006 

are capable of transporting sediment and flushing fine sediment from spawning substrate where hard substrates occur on 

the bed of the river (Elliott and others, 2009). Documented 
Table 10. Minimum and maximum hourly thermal units for Scaphirhynchus sturgeon egg development and minimum and maximum hours to complet

degrees Celsius. [Hourly thermal units is a measure designed to approximate the relation between temperature and developmental time. Red numbers are extrapolated, no data were collected for 

mal units; °C, degrees Celsius; Min, minimum; Max, maximum; >, greater than] Stage1 Description Hours to completion HTU 18 °C 19 °C 20 °C 21 °

Mean Min Max Min Max Min Max Min Max Min 

0 Start of fertilization 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

1 Unfertilized egg 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

2 Egg after turning 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

3 Light crescent stage 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

4 1st cleavage division 62.5 57 71 3.2 3.9 3 3.7 2.9 3.6 2.7 

Start 2nd cleavage division 71.9 72 72 4 4 3.8 3.8 3.6 3.6 3.4 

5 2nd cleavage (fertility rates) 77.8 72 84 4 4.7 3.8 4.4 3.6 4.2 3.4 

End of 2nd cleavage 84.4 81.5 87.5 4.5 4.9 4.3 4.6 4.1 4.4 3.9 

6 3rd cleavage division 91 91 91 5.1 5.1 4.8 4.8 4.6 4.6 4.3 

7 4th cleavage division 123.9 122.7 130.9 6.8 7.3 6.5 6.9 6.1 6.5 5.8 

8 5th cleavage division 156.7 154.4 170.7 8.6 9.5 8.1 9 7.7 8.5 7.4 

9 7th cleavage division 189.6 186.1 210.6 10.3 11.7 9.8 11.1 9.3 10.5 8.9 

10 Late cleavage 222.4 217.9 250.4 12.1 13.9 11.5 13.2 10.9 12.5 10.4 

11 Early blastula 255.3 249.6 290.3 13.9 16.1 13.1 15.3 12.5 14.5 11.9 

12 Late blastula 321 313 370 17.4 20.6 16.5 19.5 15.7 18.5 14.9 

13 Onset of gastrulation 380.6 360 399 20 22 19 21 18 20 17 

14 Early gastrula 444.1 404 565 22 31 21 30 20 28 19 

15 Middle gastrula 540.8 486 652 27 36 26 34 24 33 23 

16 Large yolk plug 583.9 573 595 32 33 30 31 29 30 27 

17 Small yolk plug 680.6 665 706 37 39 35 37 33 35 32 

18 Slit-like blastopore 771.4 706 828 39 46 37 44 35 41 34 

19 Early neural 895.8 875 914 49 51 46 48 44 46 42 

20 Broad neural plate 932.3 915.6 946.8 51 53 48 50 46 47 44 

21 Neural folds draw together 968.7 956.2 979.6 53 54 50 52 48 49 46 

22 Late neuralation 1,005.1 996.8 1,012.4 55 56 52 53 50 51 47 

23 Closed neural tube 1,041.6 1,037.4 1,045.2 58 58 55 55 52 52 49 

24 Appearance of eye protrusion 1,078 1,078 1,078 60 60 57 57 54 54 51 

25 Drawing of the lateral plates 1,187.4 1,119 1,256 62 70 59 66 56 63 53 
Stage1 Description

Hours to completion

HTU 18 °C 19 °C 20 °C 21 °

Mean Min Max Min Max Min Max Min Max Min 

26 Fusion of lateral plates 1,240 1,176 1,304 65 72 62 69 59 65 56 

27 Short elongated cardiac tube 1,300.2 1,237 1,363.5 69 76 65 72 62 68 59 

28 Straight cardiac tube 1,360.4 1,298 1,423 72 79 68 75 65 71 62 

29 Formation of cardiac tube 1,421.4 1,039 1,605 58 89 55 84 52 80 49 

30 Tail tip approaches heart 1,729.9 1,704 1,755 95 98 90 92 85 88 81 

31 Tail tip reaches heart 1,859.1 1,846 1,871.5 103 104 97 99 92 94 88 

32 Tail tip reaches head 1,988.3 1,988 1,988 110 110 105 105 99 99 95 

33 Tail tip reaches beyond head 2,060.1 2,030 2,090 113 116 107 110 102 105 97 

34 Tail tip reaches myelencephalon 2,083.8 2,189.7 2,160.5 122 120 115 114 109 108 104 

35 Hatching begins 2,107.5 2,352.6 2,231 131 124 124 117 118 112 112 

>50 percent hatch 2,509.3 2,509 2,509 139 139 132 132 125 125 119 

90 percent hatch 2,678.7 2,678.5 2,678.5 149 149 141 141 134 134 128 

End of hatch 2,848.2 2,848 2,848 158 158 150 150 142 142 136 

1Stages based on Detlaff and others (1993).

Table 10. Minimum and maximum hourly thermal units for Scaphirhynchus sturgeon egg development and minimum and maximum hours to complet

degrees Celsius.—Continued

[Hourly thermal units is a measure designed to approximate the relation between temperature and developmental time. Red numbers are extrapolated, no data were collected for mal units; °C, degrees Celsius; Min, minimum; Max, maximum; >, greater than]
86 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

spawning locations on bedrock and revetment on outside 

bends are locations where sand and finer sediment are always 

in transport, and patches of clean substrate in these areas can 

be expected to change size and change shape depending on 

flow strength. What is not known is whether, at the scale of 

spawning and embryo deposition, these patches of substrate 

are susceptible to episodic sediment deposition or abrasion 

from transporting sediment. More detailed understanding of 

where embryos are deposited is necessary to fully evaluate 

whether conditions at spawning sites can be manipulated with 

flow management.

Channel Re-Engineering

Whereas the distribution of natural hard substrate is 

patchy and discontinuous on the Lower Missouri River 

(fig. 21) (Laustrup and others, 2007), channelization of the 

Missouri River has resulted in the emplacement of large, 

angular cobble- to boulder-sized rock revetment material over most of the bank surface on the outside banks of 

nearly every bend on the lower 735 miles of the Missouri 

River. Although spawning on and adjacent to revetment has 

been documented, the suitability of this artificial substrate 

for spawning success and embryo survival is unknown. In 

particular, it is not known whether quarried rock surfaces, 

size distribution, and interstitial space are adequate to retain 

and nurture sturgeon embryos. Moreover, the geometry and 

hydraulics of outside-bend revetment differ substantially 

from conditions on natural gravel-cobble bar deposits and 

may not be conducive to embryo survival. Documented 

spawning patches on revetted outside bends are also adjacent 

to actively transporting sand dunes, and the transition zone 

between steep bank revetment and sand dunes is narrow 

(fig. 40, table 8). The typical 3 to 5 m accuracy of telemetry 

tracking and inherently variable fish behavior during spawning do not allow for precise placement of where eggs are 

released in this narrow zone. Sand dunes are transported on 

the bottom of the Missouri River for a wide range of flow 

conditions (Elliott and others, 2009); if spawning substrate 

is covered with sand, embryos may not adhere firmly and be 

buried by sand. Increased understanding of fine-scale conditions experienced by sturgeon embryos during deposition and 

incubation may lead to insights into how channel engineering 

could promote survival through this life stage.

Free-Embryo Life Stage

A free embryo is a developing fish no longer within a 

protective chorion, from hatch to the initiation of feeding. The 

small size of this life stage also challenges field assessments. 

Concerted field sampling is complemented with laboratory 

studies and deductive reasoning from physical transport 

models.

Habitat Requirements for Hatch to Free Embryo

Little is known about the biology of pallid sturgeon 

during their free-embryo life stage. This life stage, defined in 

this report as occurring from hatch to yolk absorption and first 

feeding, has rarely been caught in the wild. Only one genetically confirmed pallid sturgeon free embryo was collected 

during 2011 in the Missouri River downstream from Fort 

Peck Dam and one from the Yellowstone River in 2012. What 

information is available primarily comes from laboratory 

studies, hatchery propagation observations, and the stocking of 

propagated free embryos for field-based studies in the Missouri River.

Newly hatched pallid sturgeon embryos (7–9 mm; Snyder, 2002) are not well-developed and have a large yolk sac. 

Eyes are not pigmented for the first 2 days, pelvic fin buds do 

not appear until the fifth day post-hatch (dph), and fin development in pallid sturgeon is not complete until the fish is greater 

than 80 mm (Snyder, 2002). As a result, the newly hatched 

pallid sturgeon free embryo has limited ability to control its 

movement in the river current for several days after hatch.

Immediate Drift and Interstitial Hiding 

Hypotheses

The scientific literature on pallid sturgeon free-embryo 

habitat use is dominated by the hypothesis that drift generally 

commences immediately after hatch. Recently, a competing 

hypothesis has emerged from laboratory investigations and 

studies of other sturgeon species that free embryos may spend 

one to several days immediate post-hatch hiding in interstitial spaces in substrate (Hastings and others, 2013; Kynard 

and others, 2013; Crossman and Hildebrand, 2012). The two 

hypotheses may not be mutually exclusive; instead, there may 

be a continuum from immediate drift to interstitial hiding with 

varying probability of survival depending on drift distance 

and habitat availability when the free embryos transition to 

exogenous feeding. In the following section we review the 

evidence for both of these hypotheses. The issue is critical to 

understanding pallid sturgeon reproductive ecology in relation 

to river management because the time a newly hatched free 

embryo may spend growing in interstitial space reduces downstream drift distance and may increase chances of survival.

Continuing laboratory studies examining drift and dispersal of pallid sturgeon free embryos (Kynard and others, 2002; 

Kynard and others, 2007) and field studies done in a Missouri 

River side channel during 2004 (Braaten and others, 2008) and 

the main stem Missouri River in 2007 (Braaten and others, 

2012a) provided inferences on free-embryo drift and dispersal 

dynamics under relatively natural river conditions. These studies indicated that (1) pallid sturgeon free embryos drift and 

disperse downstream at a rate slightly less than mean water 

column velocity; (2) downstream drift and dispersal occur during day and night; (3) duration of the free-embryo drift period 

is dependent on water temperature and rate of development 
Free-Embryo Life Stage 87

and; (4) free embryos will drift and disperse several hundred 

km during ontogenetic development into exogenously feeding 

larvae, with total drift distance a function of water temperature, developmental rate, and velocity conditions in the river 

channel.

Drift distances calculated in these studies assumed drift 

commenced immediately after hatch. Although this assumption is exceedingly difficult to verify with direct observation in 

the field, it is supported by two lines of reasoning. First, is the 

lack of recruitment from known spawning populations in the 

Yellowstone–Upper Missouri River confluence area populations (Fuller and others, 2008; Braaten and others, 2009). 

Calculated drift distances from the upstream-most potential 

spawning locations at Intake Dam and Fort Peck Dam, assuming immediate drift and drift behaviors documented in field 

experiments (Braaten and others, 2008; Braaten and others, 

2012a), indicate that the free embryos would not have time to 

develop to the larval (exogenously feeding) stage before entering Lake Sakakawea. Lake Sakakawea is considered be an 

inhospitable environment for free embryo and larval sturgeon, 

although the precise mechanism has not been established. 

Dispersing sturgeon may settle in anoxic sediments upon 

reaching the reservoir, they may be vulnerable to sight feeding 

predators in the clear water, or they may be unable to find food 

or feed efficiently. If the reservoir environment is the primary 

source of mortality then the lack of drift distance may explain 

recruitment failure; however, other substantial sources of mortality cannot yet be ruled out.

The immediate drift hypothesis also is supported by 

recent captures of naturally spawned pallid sturgeon free 

embryos. Two genetically confirmed pallid sturgeon free 

embryos (estimated 0–1 dph) sampled in the Missouri River 

Basin (below Fort Peck Dam in 2011 and in the Yellowstone 

River in 2012) were collected from the drift downstream from 

natural spawning sites and substrates. Based on their stage 

of development these individuals did not spend a period of 

residency in the substrate immediately after hatching. With 

so few individuals collected, it remains uncertain what portion of free embryos actively enter the drift immediately after 

hatch or entrain into the drift immediately after hatch by river 

currents. It is unknown whether the substrate in the spawning area would provide interstitial hiding space adequate to 

retain hatched free embryos. Directly sampling the spawning 

substrate for later stages of free-embryo development would 

provide direct evidence needed to determine the timing of the 

initiation of dispersal.

The interstitial hiding hypothesis is supported by inference from other species and laboratory experiments. Recently, 

white sturgeon free embryos, a species that was previously 

hypothesized to drift immediately upon hatch, have been 

observed to spend the first few days post-hatch under rock 

cover when suitable cover was available (Kynard and Parker, 

2005, 2006; Kynard and others, 2012). Early studies collecting 

white sturgeon free embryos indicated that drift was dominated by individuals that were less than four dph (Perrin and 

others, 2003), suggesting immediate drift. Recent field and 

experimental studies, however, have related retention of white 

sturgeon free embryos to the quality and size distribution of 

substrate and whether the substrate provides adequate interstitial space (McAdam, 2011; Crossman and Hildebrand, 2012). 

In these studies, white sturgeon free embryos selected interstitial space, delaying drift by as many as 15 days. Variability of 

drift behaviors within one species suggests that a continuum of 

behaviors may exist controlled, in part, by abiotic factors such 

as substrate characteristics, current velocity, and turbulence 

(McAdam, 2012).

Experimental studies on pallid sturgeon hatch and freeembryo drift at the CERC provide some evidence consistent 

with the interstitial hiding hypothesis or facultative use of 

coarse substrate during downstream dispersal. In 2012 experiments (appendix 6), pallid sturgeon embryos attached to rocks 

and placed in an oval stream tank initially began drifting 

passively immediately after hatch in 0.14 m/s current velocity. 

During the period 0–7 dph, the drifting free embryos would, 

at various times, get caught in small eddies and slack water 

where they would sink to the bottom of the tank. Their saltatory swimming behavior off the bottom into the water column 

only infrequently allowed them to be caught by the flowing 

water and carried around the stream tank. As a result, much of 

the time during the first few days post-hatch, the free embryos 

remained in eddies and slack water. Daily mortalities of free 

embryos were high for all experimental trials until seven or 

eight dph (table 11; appendix 6).

Movement and position of the free embryos around the 

stream tank for trials 3 and 4 indicated free-embryo time 

in drift increasing until about the seventh dph then decreasing (fig. 57). The numbers of fish in eddies or pools were 

high during the period of mortalities and decreased when 

Table 11. Daily mortalities (percent) of pallid sturgeon free embryos in an artificial stream tank with an average velocity of 

14 centimeters per second from four separate experimental trials.

[--, no data]

Trial Number 

fish

Days post-hatch

1 2 3 4 5 6 7 8 9 10 11 12

1 23 -- 78 96 -- -- -- -- -- -- -- -- --

2 50 80 97 98 17 -- 20 0 20 0 0 -- --

3 47 100 40 50 33 17 30 0 0 0 0 0 --

4 20 -- -- 80 -- 100 20 75 17 0 0 0 0
88 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

free-embryo survival began to increase. Sturgeon free 

embryos from 6 dph were increasingly able to hold their 

position in the stream system and by 12 and 13 dph were no 

longer drifting (fig. 57).

These results suggest that the hydraulic conditions in 

the stream tank were lethal to pallid sturgeon free embryos 

through the first 4–5 dph. Kynard and others (2004) also tested 

drift behavior of pallid sturgeon free embryos in a flowing 

tank system with eddies. Velocities in their experiments averaged approximately 0.15, 0.20, and 0.28 m/s in three separate 

treatments. As in our experiments, Kynard and others (2004) 

reported that free embryos from 0–3 dph were unable to control 

their movements up or downstream in the flow and behaved 

as passive particles. At 0.28 m/s velocity, flow controlled the 

movement of the pallid sturgeon free embryos such that they 

never stopped drifting. Our results, however, and those of 

Kynard and others (2004) were consistent in indicating that at 

slower velocities 4 dph pallid sturgeon began to hold their position longer in the current and eddies and by 13 dph they were 

no longer drifting (Kynard and others, 2007).

One explanation for these observations is that pallid 

sturgeon free embryos have a biological necessity to drift 

immediately after hatch and their seeming inability to do so 

(because they were trapped in slack water and eddies for the 

first several dph) caused the high mortalities observed in the 

first few days after hatch. An alternative hypothesis to explain 

these observations is that pallid sturgeon free embryos require 

as many as 5 dph in a protected environment to continue 

developing before beginning the drift phase. Following this 

hypothesis, those embryos that begin to drift immediately after 

hatch are subject to higher rates of mortality.

The CERC 2012 experiments were designed based on 

the assumption that pallid sturgeon would initiate downstream 

drift immediately after hatch. However, in trial 2, gravel was 

placed on the bottom of the pool and pallid sturgeon 0–5 dph 

in that trial burrowed into and hid in the gravel interstices 

rather than drifting immediately. Mortalities in trial two were 

as high as the other trials and it may be that the single layer of 

gravel was not adequate to provide interstitial spaces for free 

embryos to be protected. Although Kynard and others (2002; 

2004) indicated that the free-embryo pallid sturgeon swam in 

the open water and almost never sought cover under rocks. In 

hatchery and laboratory settings in the absence of current, free 

embryos are predominately on the bottom of raceway tanks 

or clustered head down into a corner of a tank (James Candrl, 

U.S. Geological Survey, oral commun., 2013).

Developing the understanding necessary to select 

between the competing hypotheses is complicated by the lack 

of direct observations in the field, potential errors in inference 

based on other species, and limits of laboratory investigations. 

In particular, laboratory investigations of free-embryo drift are 

limited because of the constrained range of velocities that it 

is possible to simulate in flume settings. The experiments of 

Kynard and others (2007) documented larval drift during low, 

medium, and high velocity treatments corresponding to mean 

flow velocities of 0.17, 0.21, and 0.32 m/s, respectively. In 

the experiments completed at CERC in 2012, mean velocity 

was approximately 0.14 m/s. Velocities in both sets of flume 

experiments are substantially less than typical velocities 

observed on the main stem Missouri River (fig. 58). Progress 

in understanding the very early life history of pallid sturgeon 

free embryos may require increased realism in laboratory 

experimental conditions as well as increased resolution of 

sampling and observations in the field.

Drifting Phase

Whether free embryos drift immediately or hide for several days in interstitial spaces, eventually they disperse downstream. Free embryos progressively gain the ability to move 

on their own as they drift and undergo development from free 

embryos to larvae. Conceptually, free embryos continue to 

drift, using up their yolk sacs and developing swimming ability until they “settle” in an environment conducive to feeding 

and growth. It is important to note, however, that during the 

transition of newly hatched free embryos to swimming larvae, 

Days post-hatch 

2 4 6 8 10 12 14

0

20

40

60

80

100

120

140

0

20

40

60

80

100

0 2 4 6 8 10 12

Number of fish Number of fish

Trial 1

Trial 2

Figure 57. Total number of fish counted per day passing a fixed 

point in the stream tank in trial 1 and trial 2.
Free-Embryo Life Stage 89

the behavior, and therefore the dispersal characteristics of pallid sturgeon may change substantially. The total drift distance 

will be a function of free-embryo behavior, development, 

channel hydraulics, and water temperature, a key control on 

development rate.

The potential for long duration of drift (9–15 plus days) 

coupled with channelized flow and high velocities likely 

results in high cumulative drift distances (DeLonay and 

others, 2009). It is currently (2015) hypothesized that downstream transport of larvae into lotic environments may lead to 

mortality of larvae transitioning to exogenous feeding. Simple 

calculations in the Upper Missouri River indicate that most 

free embryos would drift into Lake Sakakawea (Braaten and 

others, 2012a). Similarly, calculations based on mean velocities in the Lower Missouri River indicate that passively drifting larvae spawned in all but the most upstream locations, are 

likely to be transported out of the Missouri River and into the 

Middle Mississippi River (DeLonay and others, 2009). Recent 

(2015) field data provide confirming evidence that pallid 

sturgeon free embryos originating in the upper segments of the 

Lower Missouri River may be exported into the Mississippi 

River. In this study fin-ray strontium:calcium ratios from four 

age-0 sturgeon captured in the Middle Mississippi River were 

interpreted to argue that the larvae originated more than 589 

km upstream in the upper part of the Lower Missouri River 

(Phelps and others, 2012b).

Calculations based on mean velocities do not address 

the potential for complex channels and flow patterns to create 

hydraulics amenable to slowing or retention of drifting free 

embryos. An approach to incorporating flow complexity into 

drift calculations is based on incorporation of retention capacity by using an advection-dispersion model (Fischer, 1973). In 

advection-dispersion models, downstream movement of particles or solutes is a function of mean channel velocity (advection) and hydraulic factors that tend to slow and spread out 

solutes or particles longitudinally (dispersion). The strength 

of dispersion in the longitudinal direction is quantified by the 

longitudinal dispersion coefficient (henceforth referred to as 

the dispersion coefficient, or DL; see appendix 8). Simulations 

of drift distance using a one-dimensional advection-dispersion 

model for the Lower Missouri River indicate that drift originating at documented spawning locations would transport 

free embryos into the Mississippi River (fig. 59), similar to 

results of the simple mean-velocity model, but with a range 

of downstream movement as result of dispersion. Our estimates of dispersion coefficients for each segment of the Lower 

Missouri River are based on a method that uses cross-stream 

velocity components from acoustic Doppler current profiler 

data (Kim, 2012) (fig. 60). This method allows us to explicitly 

consider how spatial variability in channel complexity may 

contribute to retention, although the spatial resolution is limited and may not, for example, resolve retention at the scale of 

exchange with substrate. Another important assumption is that 

drift is entirely passive, an assumption challenged by empirical data that suggest that free embryos drift downstream at a 

rate slightly slower than the mean channel velocity (Braaten 

and others, 2012a). Nevertheless, using mean velocities and 

dispersion coefficients, these models support the assertion that 

advection dominates more than dispersion, and drift of passive 

free embryos on the Lower Missouri River can be calculated 

largely as a function of mean velocities.

Free-embryo sampling at a predefined transect in the 

Lower Missouri River near St. Charles, Missouri, during 2012 

collected 336 sturgeon free embryos and larvae (appendix 7). 

Genetic analyses revealed that of 334 specimens submitted for analysis (2 of the 336 specimens were inadequately 

EXPLANATION

Kynard and others (2007) high velocity (0.28 meters per second)

Kynard and others (2007) medium velocity (0.2 meters per second)

Kynard and others (2007) low velocity (0.15 meters per second)

CERC 2012 experiments (0.14 meters per second)

Velocity at cross-section A

Velocity at cross-section B

Velocity at cross-section C

Velocity at cross-section D

A. All velocity data

Velocity, in meters per second

0 0.5 1.0 1.5 2.5

Probability density, in percent

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

B. Minimum (near-bed) velocity 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Probability density, in percent

2.0

Velocity, in meters per second

0 0.5 1.0 1.5 2.0 2.5

Figure 58. Probability density functions of velocity data 

collected using acoustic Doppler current profiler at spawning 

location documented on April 28, 2010, near river mile 202. 
90 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

preserved), 329 were identified as shovelnose sturgeon and 

5 were consistent with shovelnose sturgeon–pallid sturgeon 

hybrids. Most free embryos were captured May 1 to July 1, 

although a secondary pulse of free embryos also was detected 

in early September, indicating a possible fall spawning event. 

The bulk of the free embryos were collected near the bottom in the thalweg, consistent with drift studies in the Upper 

Missouri River (Braaten and others, 2008; Braaten and others, 

2012a).

Settling Phase

The drift period ends conceptually in “settling” of free 

embryo into environments that are conducive to feeding, 

growth, and survival. The end of the drifting period seems 

to coincide with the onset of feeding, which occurs at about 

11 dph (Snyder, 2002; Kynard and others, 2007), and notably, 

the filling of the swim bladder (Diana Papoulias, U.S. Geological Survey, written commun., 2014). At 15 dph at 19 o

C, 

free embryos must begin to feed or they will die of starvation 

within a week (Candrl and others, 2009). Settling areas also 

are thought to be areas of relatively low velocity because of 

the inability of larvae to hold position in fast water. Kynard 

and others (2007) observed that at 0.32 m/s pallid sturgeon 

free embryos could not hold position in the tank or swim 

into slow water until eight dph. In stamina experiments at 

the CERC in 2012 (appendix 6), 14-dph pallid sturgeon were 

still unable to hold position in flows greater than or equal to 

0.39 m/s. This is substantially slower than the mean water 

column velocities in the contemporary Missouri River. Pallid 

sturgeon larvae are benthic and the current velocities reported 

near the river bottom are likely a fraction of the mean column 

velocity. Understanding the relation between mean column 

velocity and near bottom velocities experienced by larval sturgeon is critical to determining habitat suitability for this life 

stage. If near bottom velocities exceed the capacity of larval 

sturgeon to control their movements in fast flowing water they 

are unlikely to avoid predation or forage effectively.

Little direct evidence exists for what constitutes settling 

habitat on the Missouri River, in large part due to the challenges of statistically sampling for tiny fish across the diverse 

habitats in the Missouri River. It has been hypothesized that 

the channelization of the Missouri River has reduced channel 

complexity and constrained successional habitat forming processes that provided the habitats needed for larval and juvenile 

fish, including sturgeon (U.S. Fish and Wildlife Service, 2000, 

2003b). Habitat restoration in the Lower Missouri River has 

coupled the goals of increased habitat diversity and complexity to the creation of shallow, slow water, bordering the main 

channel. For the purpose of setting restoration goals, the concept of shallow-water habitat (SWH) has been defined operationally as 0–5 ft (0–1.5 m) depth and 0–2 ft/s (0–0.6 m/s) current velocity (U.S. Fish and Wildlife Service, 2000); a recent 

clarification emphasized dynamics and variability of SWH 

and elaborated on its hypothesized functions: “Shallow water 

habitat provides locations for increased primary productivity, invertebrate production, and larval/young-of-year nursery 

habitat” (Olson, 2009). The low velocities incorporated in 

SWH definitions are consistent with the 0.39 m/s velocity 

threshold for larval pallid sturgeon to hold position and forage 

cited in the previous paragraph.

Several hydrodynamic modeling studies have evaluated 

the extent of SWH, patch characteristics, and relations to flow 

regime (Jacobson and Galat, 2006; Johnson and others, 2006a; 

Jacobson and others, 2009b; Papanicolaou and others, 2010). 

These studies documented the historical extent of SWH and its 

relation to discharge in the contemporary channel. Importantly, 

SWH in the engineered Lower Missouri River channel is maximized at the lowest discharges (which are incompatible with 

navigation) or in overbank floods; restored reaches showed 

substantially more SWH and less sensitivity to discharge 

(Jacobson and Galat, 2006). In general, SWH and conditions 

that we hypothesize are likely to retain free embryos are associated with hydraulic complexity and constriction/expansions 

associated with river bends and wing dikes; conditions that 

are likely to promote advection of free embryos from the main 

rol15-EMSB0-0040 Delonay Appendix Figure 59

A. Drift simulation for May 17, 2011, spawning location

River mile (RM)

800 600 400 200 0 -200 -400

Concentration, in arbitrary units Concentration, in arbitrary units

B. Drift simulation for April 28, 2010, spawning location

Mississippi River

confluence 

Day 3

Day 5

Day 7

River mile (RM)

800 600 400 200 0 -200 -400

Day 3

Day 5

Day 7 Day 9 Day 11 Day 13

Spawning

location

(RM 216)

Spawning

location

(RM 634)

Mississippi River

confluence 

Figure 59. One-dimensional advection-dispersion models of 

free-embryo drift. Longitudinal dispersion coefficients for each 

simulation were calculated using acoustic Doppler current 

profiler data collected at each spawning site. Discharge data was 

taken from USGS streamgage Missouri River at A, Boonville and 

B, Missouri River at Omaha.
Free-Embryo Life Stage 91

channel into channel-margin SWH areas. These areas of complexity, evident in measures of increased channel width and 

constriction width ratios, increase substantially from upstream 

to downstream in the contemporary river (fig. 22), but their 

role in retaining free embryos has not been documented.

Flow Regime Management

Complex interactions of discharge, hydraulics, and 

channel morphology determine drift and dispersion of free 

embryos. Changes in flow regime affect drift in two distinct 

ways: (1) discharge and mean velocity control the advection, 

or downstream transport, of free embryos, and (2) changes in 

flow regime alter channel hydraulics, which affect the dispersion and retention of free embryos. Thus, although higher 

flows would increase downstream advection of drifting pallid 

sturgeon larvae, flow pulses also have the potential to increase 

dispersion of drifting free embryos along a longitudinal 

gradient.

Models suggest that the retention of pallid sturgeon 

free embryos is affected by the availability of shallow-water 

habitat, which has been substantially reduced throughout the 

Missouri River Basin by flow regulation and channel alterations (Bowen and others, 2003; Jacobson and Galat, 2006). 

However, although total area of shallow-water habitat is 

substantially less than would have occurred in the absence of 

channel alterations, high flows have the potential to increase 

retention of free embryos by inundating low-lying alluvial 

surfaces within the active channel, secondary channels, and 

vegetated riparian habitats in the channel margins that may 

exist in natural or restored reaches of the river. The reduced 

flow velocities and high roughness values characteristic of 

these environments increase hydraulic gradients, thus promoting retention of drifting free embryos.

Channel Re-Engineering

The effects of flow regime on dispersion of free embryos 

are tightly coupled to channel morphology and free-embryo 

behavior. A spring flow pulse may affect dispersal of free 

embryos in very different ways at different stages of development, and in different parts of the river, reflecting the unique 

interaction of discharge, channel engineering, and hydraulics. 

For example, Jacobson and Galat (2006) demonstrated that in 

channelized reaches of the river that display reduced morphologic and hydraulic complexity, increases in discharge result 

in no increase in total area of shallow-water habitat until the 

channel overtops its banks. In contrast, hydrodynamic models 

of flow through reconstructed topography for the unchannelized river demonstrate that total shallow-water habitat 

would have steadily increased with discharge as low elevation 

alluvial surfaces were gradually inundated. The implications 

of this analysis for drift of free embryos is that in segments of 

the Lower Missouri River with minimal channel engineering, 

Figure 60. Longitudinal dispersion coefficients calculated for the Lower Missouri River from acoustic Doppler current profiler 

data. The wide range in values of longitudinal dispersion at each measurement site arises from the within-reach heterogeneity in 

channel morphology and hydraulic patterns. Differences in longitudinal dispersion among sections reflect the distinct geomorphic 

characteristics and styles of channel engineering used in different segments and sections of the Lower Missouri River.

rol15-EMSB0-0040 Delonay Figure 60

797799 328332 278 202 162196

Longitudinal dispersion coefficient, in square meters per second

640707745

Gavins Grand

Location along Lower Missouri River, in river miles

Ponca Sioux Kansas

100,000

10

100

1,000

10,000

1

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 

10th percentile

Individual observation above 

90th percentile

90th percentile

75th percentile
92 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

such as downstream from Gavins Point Dam, changes in flow 

regime have greater potential to increase retention of larval 

sturgeon than in reaches where hydraulic variability is less 

sensitive to discharge, such as the Big Sioux segment of the 

river (fig. 22). The coincidence of the spatial arrangement 

of the existing potential in the system to improve retention 

coincides with the development of dispersing free embryos is 

critical for growth and survival.

The distinct geomorphic characteristics and styles of 

channel engineering used in different segments of the Lower 

Missouri River are manifested in longitudinal dispersion 

coefficients calculated from ADCP data (see appendix 8). The 

lowest values of dispersion coefficients are found in the Ponca 

and Big Sioux segments where the flow field is relatively 

homogeneous (fig. 60). Increased topographic and hydraulic 

complexity within the Gavins segment translates into higher 

dispersion coefficients, reflecting the greater potential for 

retention of drifting free embryos within this reach. Notably, 

although the channel within the Kansas and Grand segments 

is highly engineered, these sections of river have the highest dispersion coefficients, because the large dikes generate 

pronounced zones of recirculation and strong cross-stream 

velocity gradients.

Present (2015) understanding of the potential for channel engineering to retain and grow free embryos to the larval 

stages is based on the concept of SWH, which defines a 

volume of habitat but fails to address the processes that lead to 

exchange between the main channel and channel-margin habitats. Improved understanding of the details of hydraulics and 

free-embryo survival at scales ranging from individual wing 

dikes to bends of rivers, combined with intensive sampling of 

free embryos and larvae, will be needed to establish how channel engineering and flow regime may be optimized to retain 

and nurture early life stages.

Larval Life Stage

Larval life stage describes a developing fish without 

yolk, feeding exogenously (table 1). This stage extends from 

the time the fish begins to feed until it has a full complement of rays in all fins, and so has the appearance of an adult 

fish in miniature. The duration of period and size of fish is 

temperature- and food-dependent. Beginning of the larval 

stage is typically equated with “settling” from the drift and 

the beginning of the ability to move independently in the 

current. Limited knowledge is available on the biology, ecology, and habitat requirements of pallid sturgeon larvae. This 

information gap stems from limited reproduction and the 

extreme rarity of collections of progeny from wild spawning 

events. Preliminary information, however, on the fundamental 

biological characteristics and ecological processes that occur 

during this critical life stage is emerging from laboratory and 

field investigations.

Habitat Requirements

Pallid sturgeon transition from endogenous-feeding free 

embryos to exogenous-feeding larvae after exposure to about 

200 cumulative thermal units (CTU; sum of daily mean water 

temperatures, in degrees Celsius, for each day of life after 

hatch) during the free-embryo life stage (Kynard and others, 2007; Webb and others, 2007; Braaten and others, 2008). 

Based on the 200 CTU requirements, age at transition from 

endogenous to exogenous feeding can be estimated for thermal regimes. For example, for exposures to daily mean water 

temperatures of 18 oC during the free-embryo life stage, yolk 

absorption and the transition to exogenous feeding occurs in 

about 11 dph (200 CTU divided by 18 oC = 11.1 days). Pallid 

sturgeon are typically 18–20 mm when the yolk is absorbed 

and they transition to exogenous feeding (Snyder, 2002; 

Braaten and others, 2008; Braaten and others, 2012b).

The transition period from endogenous to exogenous 

feeding is generally termed the “critical period” because it 

is critical that the larva finds sufficient foods of the correct 

size and type to avoid starvation (Gisbert and Williot, 1997, 

2002; Deng and others, 2003; Gisbert and Doroshov, 2003). 

The point-of-no-return (PNR) defines the maximum amount 

of time larvae have to either passively or actively find food 

(May, 1974). Defining the PNR may be beneficial for predicting larval survival in the contemporary Missouri River. 

Spawning location, temperature, flow, and to a great degree, 

velocity determine where larvae will settle and begin to search 

for food. Where larvae settle and first find food likely differs 

from the pre-dam period. Experiments at CERC in 2009 and 

2012 have identified the PNR as occurring between 276 and 

314 CTU post-hatch. Larvae receiving food at 314 and 

353 CTU had greatly reduced size and survival (< 20 percent). 

Those not receiving food were dead from starvation by 28 dph 

at 19 oC with death occurring earlier at warmer temperatures 

(table 12).

Currently (2015), data do not indicate that food (mainly 

Dipterans from the family Chironomidae) is limiting survival 

of first-feeding pallid sturgeon in the Missouri River. In the 

Upper Missouri River, the release of nearly 600,000 freeembryo pallid sturgeon in 2004 (Braaten and others, 2008) and 

2007 (Braaten and others, 2012a), and subsequent capture of 

survivors, provide the only source of information on feeding 

and growth dynamics of pallid sturgeon early life stages in 

natural settings. Larval pallid sturgeon have been reported to 

consume the larvae and pupae of Diptera and Ephemeroptera 

nymphs, exhibit growth rates of 1.9 mm/day during the initial 

13–48 dph at water temperatures averaging 23.5 o

C, and attain 

lengths of 120–140 mm by the end of September, before the 

onset of winter (Braaten and others, 2012b). Thus, at least for 

the Upper Missouri River, conditions can support feeding and 

growth of pallid sturgeon during the early life stages. Evidence that pallid sturgeon can survive or grow, however, does 

not suggest that conditions are optimum, or that the species 

is realizing its full potential for survival or growth. Specific 
Larval Life Stage 93

information on pallid sturgeon feeding and growth is lacking 

for other regions of the Missouri River and Mississippi River.

Few studies have assessed habitat use characteristics of 

age-0 pallid sturgeon, and limited information is available to 

discern habitat requirements. In the Upper Missouri River, 

Braaten and others (2012) collected 10 age-0 pallid sturgeon 

(19–87 mm) surviving from the free-embryo release stud-

ies. The age-0 pallid sturgeon were collected at sites where 

minimum depth varied from 1.0 m to 4.3 m (mean = 2.9 m) 

and maximum sample depth varied from 1.5 m to 5.6 m (mean 

= 4.3 m) (David Fuller, Montana Fish Wildlife and Parks, 

written commun., 2012). Four presumed age-0 pallid sturgeon 

(identification based on morphometrics and meristics rather 

than genetics) were sampled in the Mississippi River from 

habitats where mean bottom velocity was 0.25–0.65 m/s and 

depth varied from 2.7 to 3.6 m (Hrabik and others, 2007). In 

laboratory settings, young pallid sturgeon (27–200 mm) tend 

to select sand substrates and deep water habitats (Allen and 

others, 2007).

Given the rarity of age-0 pallid sturgeon, some research 

in the Missouri and Mississippi Rivers has focused on the 

biology, ecology, and habitat selection of age-0 shovelnose 

sturgeon and undifferentiated Scaphirhynchus spp. to make 

inferences about pallid sturgeon (Braaten and Fuller, 2007; 

Braaten and others, 2007; Kappenman and others, 2009; Tripp 

and others, 2009; Ridenour and others, 2011; Phelps and 

others, 2012a; Phelps and others, 2012b; Sechler and others, 

2012, 2013). Results from shovelnose sturgeon and undiffer-

entiated Scaphirhynchus spp. suggest some commonalities to 

known information from pallid sturgeon (for example, feeding 

and growth), but the extent to which inferences comprehen-

sively depict the early life ecology and habitat requirements of 

pallid sturgeon is unknown.

Most studies linking catches of age-0 pallid and shov-

elnose sturgeon to habitats have been based on measures of 

depth, velocity, or substrate in the vicinity of nets or trawls, 

stratified by meso- or macro-habitat units (Ridenour and 

others, 2011; Sechler and others, 2012). These habitat char-

acterizations help define conditions at sampling locations 

where fish are found, but fail to address aspects of habitat 

complexity, dynamics, and interactions and exchanges among 

habitats. Preliminary studies of the habitat context associ-

ated with age-0 Scaphirhynchus larval trawl catches on the 

Lower Missouri River have focused on detailed and continu-

ous maps of bathymetry and velocity fields (DeLonay and 

others, 2014). These studies provide an understanding of the 

hydraulic processes responsible for transport and retention of 

small fish, plankton, and organic matter as well as providing a 

more general understanding of habitat use compared to avail-

ability (fig. 61). Suitability and interactions of channel-margin 

habitats vary considerably with discharge, indicating a need 

for well-informed hydraulic models to quantify availability 

through time and to relate to flow regime. Availability of 

conventionally delineated SWH units (serving as an opera-

tional metric for age-0 sturgeon habitat) in channelized river 

segments can be sensitive to discharge at very low flow but 

Table 12. Effect of day post-hatch cumulative thermal units of first feeding on survival of free-embryo pallid sturgeon reared at constant water temperature (19 degrees 

Celsius) and water temperature fluctuating in accordance with modeled lower Missouri River temperatures during drift (16–24 degrees Celsius).

[Cumulative thermal units is a measure designed to approximate the relation between temperature and developmental time. Pallid sturgeon larvae were fed beginning at different days post-hatch in two temperature trials. Values within a column with the same superscript are not significantly different at p<0.05. ±, plus or minus; °C, degree Celsius; DPH, days post-hatch; CTU, cumulative thermal units; SD, standard deviation; TL, total length; mm, millimeters; --, no data]

Constant temperature (19.0±0.1 °C) Flucuating temperature (16.0–24.0 °C)

First fed

(DPH) CTU Survival percent (mean±SD) TL, in mm (mean±SD) Number of fish First fed (DPH) CTU Survival percent (mean±SD) TL, in mm (mean±SD) Number of fish

11 200 47±13bc 29.9±1.4 3 11 203 37 22.7 2

13 237 70±8a 30.9±0.5 3 13 246 43±8a 21.5±0.5 4

15 276 65±9ab 26.0±0.4 3 14 267 38±8a 21.3±0.3 417 314 23±23cd 24.8±1.6 3 16 307 19±13ab 21.7±1.8 419 353 7±6d 25.9±1.9 3 18 349 3±3b 20.5±0.5 4

Control* -- 0d -- 3 Control* -- 0b -- 4

*Control, individuals were never fed and all died by 28 days post-hatch.
Digital imagery from U.S. Department of Agriculture National Agriculture Imagery Program, digital data, 2011 Universal Transverse Mercator projection, zone 15 Discharge on 

August 18, 201streamgage 06was 195,000 c

River miles from U.S. Army Corps of Engineers, 1960 Riv

162 0 100 200 METERS 0 500 1,000 FEET EXPLANATIO

Reg

Traw

Depth, in mete

1.

19

162 92°22’05” 92°21’40” 92°21’15” 38°44’ 38°43’45” 38°43’30” Figure 61. Multibeam bathymetry near river mile 162 and U.S. Fish and Wildlife Service age-0 sturgeon sampling trawl endpoints. Mapped on Augus

orientations indicate that the area is a zone of transport of sediment and other constituents from the main channel to the channel-margin habitat. Fro2014.
Larval Life Stage 95

insensitive to higher flows until they go overbank (Jacobson 

and others, 2009). In a nonchannelized reach of the Lower 

Missouri River and in restored reaches, SWH is more abundant for a wide range of discharge (Jacobson and Galat, 2006; 

Jacobson and others, 2009b). These results indicate that SWH 

is amenable to quantification and restoration, but the existing 

linkages between SWH and conditions that affect pallid sturgeon survival and recruitment are poorly described. Existing 

occupancy and growth/survival data for age-0 sturgeon are not 

sufficient to conclude that SWH captures the full complement 

of habitat conditions that are supportive of age-0 sturgeon.

Field and laboratory studies have been done to elucidate 

potential factors limiting survival of pallid sturgeon during the 

early life stages. In the Upper Missouri River Basin, fragmentation induced by dam and reservoir construction has emerged 

as a leading hypothesis eliminating survival of pallid sturgeon. 

Specifically, as pallid sturgeon free embryos require an extended 

length of free-flowing river downstream from hatch locations to 

complete development (Kynard and others, 2007; Braaten and 

others, 2008; Braaten and others, 2012a), reservoirs prematurely 

terminate the drift period, disrupting the natural drift and dispersal processes of pallid sturgeon. The specific mechanism(s) 

of mortality in reservoir environments is unknown, but likely 

includes factors acting on the free embryo or larval life stage or 

both. As applied to the Lower Missouri River where dams are 

not present, extended drift requirements of free-embryo pallid 

sturgeon coupled with increased velocities of the river could 

transport Missouri River-spawned free embryos to the Mississippi River where the transition to exogenous feeding would 

occur (fig. 59) (DeLonay and others, 2009; Phelps and others, 

2012b). In this situation, the lack of exogenous-feeding and 

age-0 pallid sturgeon in the Missouri River would not necessarily reflect mortality in the Missouri River, rather physical transport out of the system. Age-0 pallid sturgeon (as confirmed with 

genetic testing) are exceptionally rare in the Mississippi River 

(Boley and Heist, 2011), possibly indicating that spawning is 

limited or that survival during the early life stages is low.

Predation is well-recognized as a source of mortality 

acting on fishes during the early life stages (Houde, 2008); 

however, the role of predation on the exogenous-feeding 

and age-0 life stages of pallid sturgeon has received limited 

inquiry. In the Upper Missouri River, gut contents of several 

potential predators (burbot, Lota lota; channel catfish, Ictalurus punctatus; freshwater drum, Aplodinotus grunniens; 

goldeye, Hiodon alosoides; northern pike, Esox lucius; sauger, 

Sander canadense; shovelnose sturgeon; and walleye, Sander 

vitreus), did not reveal remains or any evidence that age-0 

Scaphirhynchus spp. were consumed (Braaten and Fuller, 

2002). French and others (2010) completed laboratory trials 

with age-0 pallid sturgeon and fathead minnows (Pimephales 

promelas) as prey, and flathead catfish (Pylodictis olivaris), 

smallmouth bass (Micropterus dolomieu), and walleye as 

potential predators. The authors concluded that predation risk 

from smallmouth bass and walleye was low on pallid sturgeon 

when an alternative prey type was available; however flathead 

catfish consumed larval pallid sturgeon 40–50 mm in length 

in proportion to their availability. Flathead catfish introduced 

into the Satilla River, Georgia have been reported to consume Atlantic sturgeon (Acipenser oxyrinchus) to as much as 

160 mm (Flowers and others, 2011) raising concerns that predation by catfish may be responsible for the decline of native 

sturgeons. Flathead catfish are a prominent native predator 

in the Lower Missouri River, and have been documented to 

consume sturgeon (Hogberg, 2014).

Population Augmentation

Recapture data of hatchery progeny released as larvae in 

the Yellowstone and Upper Missouri Rivers suggest that survival rates from the larval stage through winter to age 1 range 

from 32 to 79 percent (Jay Rotella, Montana State University, 

written comm., 2012). This suggests that pallid sturgeon population augmentation at the larval stage is a possible strategy 

if suitable habitats are available. What constitutes suitable 

habitat for larval sturgeon remains a challenging obstacle for 

designing augmentation strategies. At regional scales augmentation of populations with larval (or older) fish may be more 

effective if release locations are based on an understanding 

of where free embryos and larval fish would tend to settle out 

from the drift under natural conditions or, in the engineered 

and fragmented river, where the larvae would settle out downstream from contemporary spawning locations.

Flow Regime Management

Provided that the present understanding of what constitutes suitable habitat for larval pallid sturgeon is accurate, 

analyses indicate those habitats are relatively insensitive to 

flow regime in the Lower Missouri River, except at extremely 

low discharge or flood discharges that are generally outside of 

flow-management options (Jacobson and Galat, 2006; Jacobson and others, 2009b). Understanding of sensitivity to flow 

regime may change as refinements are made in understanding 

habitat suitability for this life stage. In the Upper Missouri 

River, flow regime management would not be relevant to the 

larval life stage for most conditions because survival of the 

embryo and free-embryo stages appears to be limited by drift 

distance. An exception would be if Lake Sakakawea were 

managed to reduce water levels and extend the available drift 

distance, provided that extended fluvial conditions in the upper 

end of the reservoir resulted in suitable flow and substrate 

conditions for larval sturgeon. The amount of additional drift 

distance needed and the extent of the drawdown necessary to 

attain that length of additional river has not been determined.

Channel Re-Engineering

Channel re-engineering can change hydraulic complexity and the ranges of depth, velocity, and substrates available 

to larval pallid sturgeon. Providing more larval and juvenile 
96 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

habitat has been one of the reasonable and prudent alternatives of the Missouri River Biological Opinion (U.S. Fish and 

Wildlife Service, 2000, 2003) and one of the main objectives of 

the SWH component of the Missouri River Recovery Program. 

Although progress is being made toward the eventual goal of 

20–30 acres per mile of SWH, the biological results have been 

equivocal (Schapaugh and others, 2010), and concerns have 

been raised that the operational definition of 0–5 ft (0–1.75 m) 

and 0–2 ft/s (0–0.6 m/s) ignores ecological complexity and may 

result in nonfunctional acreage (National Research Council, 

2011). A process-based understanding of how abiotic and biotic 

processes are linked in channel-margin habitats would provide 

improved guidance to channel re-engineering so it will contribute to growth and survival of larval (and older) pallid sturgeon.

Juvenile Life Stage

The juvenile life stage consists of sexually immature fish 

(table 1). The juvenile life stage extends until the fish begins 

gametogenesis and enters its first reproductive cycle. During 

this period, the juvenile pallid shifts its diet from insects to fish 

(Gerrity and others, 2006; Grohs and others, 2009). Substantially greater amounts of information are available for juveniles compared to free embryo and larval life stages because of 

information collected in the field from hatchery-raised fish and 

because juveniles are amenable to laboratory experiments.

Habitat Requirements

Observed conditions where pallid sturgeon have been 

collected as part of the Pallid Sturgeon Population Assessment Program (PSPAP) between 2003 and 2010 (Welker and 

Drobish, 2009) provide notable differences between juveniles 

and adults that suggest differences in habitat use (fig. 62). 

During late spring through fall, juveniles found in the Missouri River above Gavins Point Dam tended to be collected 

in cooler temperatures than adults, with the reverse pattern 

observed below Gavins Point Dam. However, during this same 

season, juveniles tended to be collected in shallower, slower 

water than adults throughout the river. During late fall through 

early spring, throughout the river, juveniles tended to be 

collected in warmer water than adults with depth differences 

still present but not as dramatic as observed during late spring 

through fall, and with no obvious differences in velocity.

Concentration of juveniles in habitats that are shallower and slower than the main channel may expose them 

to elevated risks associated with water quality. In particular, 

episodes of decreased dissolved oxygen (“sags”) and seasonal 

warm temperatures in the Lower Missouri River in recent 

years at USGS streamgaging stations have approached the 

limits of physiological tolerance for juvenile pallid sturgeon 

(Blevins, 2011). DeLonay and others (2009) also observed 

these oxygen sags during their telemetry studies of adult 

pallid sturgeon. If such extreme conditions were to become 

more widespread and persistent, it is unknown to what extent 

juvenile sturgeon would be able to find water-quality refugia 

within the well-mixed contemporary Missouri River channel.

For early juvenile stages, restricted availability and intake 

of food may reduce growth rates, alter distributions, and limit 

densities of individuals across habitat types (Deng and others, 

2003). Therefore, viability through this life stage is primarily 

affected by predation, competition with other insectivorous 

species for available, appropriate food and habitat (Wildhaber 

and others, 2011a).

Growth of juvenile pallid sturgeon to adults is highly 

affected by diet composition (Grohs and others, 2009) with 

chironomids (Order: Diptera) and mayflies (Order: Ephemeroptera) serving as important components of early juvenile 

diets (Sechler, 2010; Sechler and others, 2013). Pallid sturgeon 

diets shift from macroinvertebrates to fish as they grow. Juvenile pallid sturgeon between 350 and 500 mm fork length (FL) 

have been documented to have diets that consist of 57 percent 

fish, whereas juvenile pallid sturgeon greater than 500 mm FL 

consumed 90 percent fish (Gerrity and others, 2006; Grohs 

and others, 2009). Isotope analyses of pectoral spines support 

gut analyses and indicate that the diet shift of juvenile pallid 

sturgeon from invertebrates to principally fish likely occurs at 

or before 500 mm FL, well before pallid sturgeon reach reproductive maturity (French, 2010).

Mortality of early juvenile stages (that is, late stage age-0 

larvae) appears to be primarily driven by prey availability; 

most research focuses on juvenile health as it relates to nutrient sources rather than physical habitat (Wildhaber and others, 

2011a). However, alterations to physical habitat including longitudinal fragmentation by reservoirs, temperature reductions 

below dams, channelization, and bank stabilizations likely 

reduce the production and retention of food (Wildhaber and 

others, 2011a). This was particularly evident in the Mississippi 

River in 2006, a year that represented high water temperatures 

and low stage heights. During this period about 30 percent of 

age-0, wild-caught Scaphirhynchus spp. were determined to 

have empty stomachs. Similar sampling efforts in years with 

greater discharge and lower temperatures (considered to be 

more hydrologically favorable) typically yielded 1–8 percent 

of age-0 fish with empty stomachs (Sechler, 2010).

Limited prey sources increase mortality and may suppress growth in surviving juveniles (Deng and others, 2003; 

DeLonay and others, 2009). No clear relations have been 

documented between abiotic factors (for example, water temperature) and pallid sturgeon recruitment, but early diet and 

growth are considered to affect recruitment into adult, spawning populations (DeLonay and others, 2009; Sechler, 2010). 

Studies of other fish diets, including the similar shovelnose 

sturgeon, have reported that higher river stages are associated with increased levels of food intake (Held, 1969; Modde 

and Schmulbach, 1977). Higher river stage may increase and 

improve foraging habitat, and reduce competition among individuals (Sechler and others, 2013) or improve physical conditions for prey production or foraging, such as water temperature and turbidity (Blevins, 2011). The decrease of turbidity 
0

5

10

15

20

25

0

1

2

3

4

5

6

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0

5

10

15

20

25

Fork length less than 250 millimeters

Fork length between 250 and 499 millimeters

Fork length between 500 and 750 millimeters 

Fork length greater than 750 millimeters

0

1

2

3

4

5

6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

November–End of June Sampling Season

July 1–October 31 Sampling Season

Upper

Missouri

Fort

Randall

Gavins

Point

Ponca

St. Louis

Upper

Missouri

Fort

Randall

Gavins

Point

Ponca

St. Louis

Upper

Missouri

Upper

Missouri

Fort

Randall

Gavins

Point

Ponca

St. Louis

Upper

Missouri

Fort

Randall

Gavins

Point

Ponca

St. Louis

Upper

Missouri

Temperature, in degrees Celsius Temperature, in degrees Celsius

Depth, in meters Depth, in meters

Velocity at sixty percent of depth, 

in meters per second

Velocity at sixty percent of depth, 

in meters per second

EXPLANATION

Standa

Figure 62. Mean and standard deviation of riverine habitat characteristics when pallid sturgeon were captured in the Pallid Sturgeon Population A

2003 to 2010. Fish are grouped by sample segments, season, and length categories where data used are from the randomized sampling protocol.
98 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

in the Missouri River due to anthropogenic alterations has 

improved conditions for species that may be in competition 

with juvenile pallid sturgeon for similar food sources and 

potential pallid sturgeon predators (Blevins, 2011; Wildhaber 

and others, 2011a). Juvenile pallid sturgeon are easily captured by potential predators but, in laboratory settings, do not 

seem to represent a preferred prey source if other options exist 

(French and others, 2010).

Competition

To ensure adequate growth and survival of young sturgeon, food availability must be high, whereas competition 

and predation risk must be low for these life stages to recruit 

successfully to the adult population within any given river 

reach. Sturgeon are subject to intra- and interspecific competition at each life stage because of the number of benthic species 

found in the Missouri River (Berry and others, 2004; Wildhaber and others, 2012), all of which may be competing directly 

for space and food resources. Each of these benthic species 

may use slightly different habitat, food resources, or feeding 

strategies to reduce competition and improve foraging success; 

however, in highly modified habitats the availability and distribution of food resources may reduce foraging success of some 

species and thereby increase competition. Recent field studies 

have demonstrated that juvenile pallid and shovelnose sturgeon use the same habitat during nonwinter periods when rates 

of food consumption and growth are expected to be greatest 

(Gerrity and others, 2008). Studies of white sturgeon in the 

Kootenai River (not shown) report evidence of density-dependence mortality among hatchery-stocked juvenile sturgeon 

during the first year of life, possibly as a result of competition 

for food or habitat resources, or increased predation (Justice 

and others, 2009).

Diet studies of juvenile shovelnose and pallid sturgeon 

indicate that both feed primarily on invertebrates including 

chironomids, trichopterans, and ephemeropterans (Hoopes, 

1960; Held, 1969; Modde and Schmulbach, 1977; Gerrity and 

others, 2006; Braaten and Fuller, 2007; Hoover and others, 

2007; Wanner and others, 2007). The specific mode of feeding, 

the ability of young sturgeon to feed on drifting organisms, 

and the effects of temperature, turbidity, and substrate on 

feeding have not been thoroughly examined. This information 

is critical to understanding the relation between habitat and 

survival of early life history pallid sturgeon.

Evidence (Gerrity and others, 2006; Hoover and others, 

2007) exists for several Macrhybopsis chubs as important 

prey items for pallid sturgeon adults. Since adult chubs likely 

use the same habitats and food resources they also may be 

predators and competitors of pallid sturgeon during early life 

stages. Recently, populations of several of these chub species have declined (Hesse and others, 1989; Galat and others, 

2005a), which may hinder growth and development in adult 

pallid sturgeon while simultaneously decreasing competition 

for early juveniles.

Food availability is a potentially limiting factor that is 

confounded with questions of habitat availability and competition. Even if juvenile pallid and shovelnose sturgeon are 

able to find preferred habitat with minimal competition, poor 

growth and survival will result if the necessary food resources 

are not present in those habitats. The complexity of the Missouri River makes it nearly impossible to document factors 

affecting food availability and habitat selection of juvenile 

shovelnose and pallid sturgeon in the wild (DeLonay and others, 2009; Reuter and others, 2009; Bonnot and others, 2011a). 

Therefore, these factors are commonly investigated in the 

laboratory under controlled conditions.

A laboratory study was done to understand habitat and 

food selection of juvenile sturgeon and the shoal chub (Macrhybopsis hyostoma). The objective of this study was to assess 

habitat choice as it relates to food availability, examining the 

strength of substrate selection in the presence of food and 

whether that selection changed with varying levels of turbidity. The purpose of studying both sturgeon species along with 

shoal chubs was to gain a better understanding of the potential 

competition for resources between species and whether or not 

management actions affect the species differently.

The CERC laboratory study consisted of a series of 

24 isolated aquaria each equipped with their own computercontrolled lighting (visual and infrared) and heating system. 

Each tank was assigned a random combination of clay and 

sand substrate relative to tank side, resulting in a half clay/

half sand, tank bottom. One fish was placed in each tank and 

tanks were continuously monitored using a closed-circuit 

camera and digital video recorder. To test light intensity as 

a surrogate for turbidity the tanks were randomly assigned 

to two treatments. One set of tanks was kept in continuous 

darkness (monitored with infrared), whereas the second set 

of tanks were on a 12 hour light: 12 hour dark cycle. To test 

food consumption (that is, growth rates), one-half of each 

of the two lighting groups were fed a maximum ration daily, 

whereas the other one-half was fed one-half of that maximum 

ration. To test the effect of food on substrate choice, delivery 

of food to a given substrate type (that is, clay or sand) was 

randomized among tanks and compared to habitat choice 

without food. Pallid and shovelnose sturgeon tended to forage 

on clay compared to sand, at least under zero velocity conditions. Shoal chubs reported less substrate-related selection, but 

similarity in habitat choice among all three species indicated 

that there is potential for competition and, thus, possible limitations of habitat and food resources (fig. 63). These results 

provide initial data needed to model the potential population 

impacts of these behaviors in the context of available food and 

habitat present in the Lower Missouri River. This information is useful for developing the submodel for this life stage in 

the overall sturgeon population model (Bajer and Wildhaber, 

2007; Wildhaber and others, 2007a, 2011a) as part of a larger 

adaptive management approach directed at increasing pallid sturgeon populations through habitat alteration within the 

Missouri River. Additional data are needed to determine if 

sturgeon at this life stage forage in groups and use social cues 
Juvenile Life Stage 99

to find and exploit resources more effectively. An additional 

submodel would be required if social interactions are shown to 

have significant benefits.

Survival of Juveniles

Survival rates of stocked pallid sturgeon in the highly 

altered Lower Missouri River have been estimated to be 

0.051 (SE = 0.008) for age-0 fish and 0.686 (SE = 0.117) 

for age-1 fish (Steffensen and others, 2010). Pallid sturgeon 

in the Lower Missouri River typically are stocked as age-1, 

juvenile fish at 9 inches (23-cm) or larger. Some stocking has 

occurred using older, larger fish. The survival rate of age-1+ 

fish increased to 0.922 (SE = 0.015) (Steffensen and others, 

2010).

Population augmentation practices have resulted in concentrations of surviving stocked fish in the upper part of the 

Lower Missouri River where they had been stocked, whereas 

no such concentration of stocked fish occurs in the part of 

the Lower Missouri River near its mouth where stocking 

also occurred (Scott Holan, University of Missouri, written 

commun., 2014). The latter observation may suggest higher 

mortality or dispersal or both to the Mississippi River for 

age-0 and age-1 hatchery-reared pallid sturgeon stocked in the 

lower part of the Lower Missouri River. In contrast, a 2-year 

study with radio-tagged juveniles in the Upper Missouri River 

determined that stocked sturgeon did not disperse immediately 

(Oldenburg and others, 2011). These observations suggest that 

the locations chosen for stocking may be critical to improving 

survival.

Population Augmentation Management

Under the Propagation and Stocking Plan for the pallid sturgeon the U.S. Fish and Wildlife Service recommends 

stocking age-1 fish at a rate of 24.5 fish per river kilometer 

Shovelnose sturgeon

Proportion of time

0

0.2

0.4

0.6

0.8

1.0

1.2

Shoal chub

Clay with food Sand with food

Clay with food Sand with Food

0

0.2

0.4

0.6

0.8

1.0

1.2

Pallid sturgeon

0

0.2

0.4

0.6

0.8

1.0

1.2

Cmax food level without daylight

Cmax food level with daylight

Half of Cmax food level without daylight

Half of Cmax food level with daylight

Error bar—Standard deviation

EXPLANATION

[Cmax, maximum consumption] 

Figure 63. Proportion of time fish were active in clay and sand treatments with food. Treatments consisted of food fed 

at maximum consumption (Cmax) or one-half of maximum consumption with or without daylight.
100 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

per year in the Lower Missouri River and limiting offspring 

stocked from a single female to 10,000 individuals (U.S. Fish 

and Wildlife Service, 2008). The success of these stocking 

efforts is dependent on the consistent augmentation efforts that 

preserve the genetic diversity of populations, while stocking 

progeny that will survive to contribute to subsequent generations to increase the effective population size. Whereas environmental factors and stocking locations have the potential 

to affect the survivorship of juvenile pallid sturgeon, survival 

rates may be high and there is no documented evidence that 

habitat, food availability, or competition limits this life stage. 

Thus, recruitment failure may be occurring before pallid sturgeon transition to the juvenile stage.

Flow Regime

To the extent that flow regime affects spawning locations of reproductive adults and, therefore, the starting point 

for downstream drift, flow regime may indirectly affect where 

larval fish settle and the river location where juvenile life stage 

begins. Within that location, flow regime may affect availability of habitat types. The areas where age-0 pallid sturgeon 

(early juveniles mostly less than 100 mm fork length) have 

been documented on the Lower Missouri River (0.5–0.7 m/s 

velocity near the bottom and 2–3 m depth; Ridenour and others, 2011) are sensitive to discharge variation at low flows and 

overbank flows. In the highly engineered Kansas segment of 

the Lower Missouri River, these habitats decrease substantially 

with increasing discharge, especially at discharges greater 

than 75 percent of the median. Whereas, in the more natural 

channel morphology of the Gavins segment, these habitats 

increase substantially with increasing discharge, peaking at 

about the median discharge (Jacobson and others, 2009b). 

Importantly, data on habitat occupation of juveniles are limited 

on the Missouri River and have not been related directly to 

availability to determine selection. Moreover, habitat occupations in the highly altered Lower Missouri River cannot be 

assumed to represent ideal locations (Wildhaber and others, 

2011a). Although present (2015) information does not indicate 

that physical habitat is a limiting factor for juvenile growth 

and survival at current low densities, it is possible that food 

transport into habitat areas or habitat-mediated competition is 

affected in part by flow regime.

Channel Re-Engineering

Re-engineering of channel morphology of the Lower 

Missouri River has focused on establishing SWH with the 

goal of increasing rearing habitat for larval and juvenile pallid sturgeon (U.S. Fish and Wildlife Service, 2007). Age-0 

sturgeon, pallid and shovelnose, have been most frequently 

recorded around dikes and island areas and rarely are observed 

in the main channel, however depths and velocities in these 

areas tend to be greater than those defined for SWH in the 

Lower Missouri River (Phelps and others, 2010a; Ridenour 

and others, 2011). Age-1 and older juvenile-specific habitat 

use is rarely recorded but is probably no shallower or slower 

than that used by early-stage juveniles. Channel re-engineering has been reported to be effective in creating SWH and 

increasing habitat complexity (Jacobson and Galat, 2006) 

but, as noted above, the linkages to growth and survival of 

pallid sturgeon juveniles have not been established. Evidence 

suggests that channel re-engineering activities themselves, 

such as use of cutter-head dredges, may in specific cases lead 

directly to increased juvenile mortality (Hoover and others, 

2011), although the long-term benefits of habitat creation may 

outweigh short-term losses of individuals.

State of Scientific Understanding 

of Pallid Sturgeon Ecological 

Requirements and Implications for 

River and Species Management

In this section we discuss the present (2012) state of 

scientific understanding of pallid sturgeon ecological requirements, information gaps, and the application of ecological 

understanding to restoration and management decisions. We 

begin with the broad subject of pallid sturgeon genetics across 

the landscape, followed by focused discussion about what 

we know and what we do not know about ecological requirements and survival of reproductive adults, hatch to larval life 

stages, and YOY to juvenile life stages. We complete this 

section with discussion of applications of ecological information to the types of river restoration and management actions 

under consideration on the Missouri River to retain genetic 

diversity.

Landscape Scale Genetics

Development of genetics methods, decreased analysis 

costs, and concerted genetic sampling efforts have resulted 

in broadened understanding of genetic structuring of the 

pallid sturgeon throughout the past 5 years (Schrey and 

Heist, 2007; Eichelberger and others, 2014). Documentation 

of genetic structure is central to population augmentation 

strategies. Moreover, understanding how genetically defined 

subpopulations formerly and presently (2015) relate to the 

template of physical habitat is critical to understanding 

where and what types of habitats need to be restored on the 

Missouri River.

State of Understanding

Genetic studies have suggested rangewide genetic 

structuring of pallid sturgeon populations (Campton and 

others, 2000; Tranah and others, 2001; Schrey, 2007; 

Schrey and Heist, 2007). These data indicate that genetic 
State of Scientific Understanding of Pallid Sturgeon Ecological Requirements and Implications for River and Species Management 101

structuring of pallid sturgeon populations is natural and 

predates anthropogenic migratory barriers (Schrey, 2007; 

Schrey and Heist, 2007), suggesting that reproductive 

isolation was established before construction of the dams 

on the Missouri River. The historic genetic structure likely 

has been altered by past stocking of juvenile pallid sturgeon 

that transferred genetic stocks from the Middle Mississippi 

and Upper Missouri Rivers into the Lower Missouri River 

(Schrey and Heist, 2007).

Genetic introgression (hybridization) between pallid 

and shovelnose sturgeon has been occurring for several 

generations (Carlson and others, 1985; Tranah and others, 2004; Schrey and others, 2011). Evidence of genetic 

introgression has been reported in all management units, 

but appears to be highest in the southern extreme of the 

range (Schrey and others, 2011). Reproductive studies 

using telemetry by the CSRP have included genetically 

determined hybrid sturgeon and have confirmed that they 

spawn in the Lower Missouri River. Studies for the CSRP 

have been unsuccessful in collecting pallid sturgeon free 

embryos below known spawning sites and from continually 

sampled stations near the mouth of the Missouri River, but 

hybrid pallid/shovelnose sturgeon have been found in both 

types of collections (appendix 7).

Information Gaps

Studies are underway to better characterize the rangewide 

genetic structure of wild pallid sturgeon (wild is used here 

to denote fish that have been spawned in the river naturally, 

without human intervention). It is not known, however, what 

mechanisms were responsible for creating or sustaining the 

pre-dam structure on the landscape, or whether measured 

genetic differences translate into important locally adapted 

traits that affect growth and survival (Meyer, 2011). Various 

spatial, temporal, and biological factors may have acted alone 

or in concert to create the observed population structure, and it 

is unclear whether those factors and their effect remain intact 

in the altered Missouri River system.

Additionally, the degree to which the historic genetic 

structure has been affected by the substantial intra-basin transfer of genetic stocks in past population augmentation efforts is 

not clearly understood at this time (Krentz and others, 2005; 

U.S. Fish and Wildlife Service, 2008). The effect of population 

augmentation on genetic structure may become apparent soon 

as numbers of hatchery-origin fish exceed wild pallid sturgeon 

and begin spawning (DeLonay and others, 2009).

Reproductive interactions between pallid sturgeon and 

the more common and sympatric shovelnose sturgeon are 

poorly understood at this time. The geographic extent, distribution, and rates of hybridization between the two species and 

the threat of hybridization to the recovery of pallid sturgeon 

across the range of the species are poorly understood (Schrey, 

2007).

Information Needs

A more robust understanding of the pre-dam, rangewide 

genetic structure of the pallid sturgeon population is needed to 

evaluate the necessity for the delineation of distinct population 

segments (DPS), as described in the revised Pallid Sturgeon 

Recovery Plan (U.S. Fish and Wildlife Service, 2014). The 

Pallid Sturgeon Conservation Augmentation Program (PSCAP) 

requires population genetics structure information to guide 

the selection of individuals for use as broodstock within the 

management units where propagation is advisable (U.S. Fish 

and Wildlife Service, 2008). Genetic structure information, 

combined with knowledge of spawning locations and the early 

life history and dispersal of young sturgeon from spawning 

sites (defining the population’s functioning geographic range), 

would provide the data necessary to devise the best possible 

strategies for population augmentation. Improved movement 

and distribution data for hatchery progeny would provide 

managers with information necessary to balance the risks and 

benefits of population augmentation in genetically structured 

populations to best retain local geographic adaptations.

Although spawning of hatchery-origin pallid sturgeon has 

been documented (DeLonay and others, 2009; DeLonay and others, 2010; DeLonay and others, 2012; DeLonay and others, 2014), 

it is unknown whether they respond to environmental spawning 

cues and available habitat in a similar manner as wild fish. More 

information is needed to evaluate the relative contribution of 

hatchery-origin fish to reproduction, recruitment, and recovery.

Information necessary to determine the consequences 

of hybridization is lacking. Mechanisms that contribute to 

hybridization may include low population densities, barriers 

to migration, altered spawning habitat, and disrupted environmental cues that would ordinarily serve to synchronize reproductive readiness and behavior in unaltered systems. Given the 

longitudinal life history of the pallid sturgeon documented by 

CSRP studies, the presence of substantial numbers of hybrid 

sturgeon in the Middle Mississippi River would suggest that 

hybridization by spawning adults is a concern on the Lower 

Missouri River (appendix 7). No comprehensive studies 

examining the extent and cause of hybridization currently 

(2015) exist on the Missouri River and proposed management 

actions rarely consider preventing hybridization or curtailing 

the potential threat as an explicit objective.

Reproductive Adults and the Spawning 

Population

The Missouri River biological opinions (U.S. Fish and 

Wildlife Service, 2000, 2003), sturgeon science workshops 

(Quist and others, 2004; Bergman and others, 2008), and the 

2005 Spring Rise Plenary Group process (Jacobson and Galat, 

2008) all put substantial emphasis on the need to understand 

adult sturgeon reproductive requirements. As a result, CSRP 

research prioritized understanding of basic reproductive biology, starting with adults.
102 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

State of Understanding

Little was known about pallid sturgeon reproduction 

before 2005. No spawning had been documented outside of 

hatcheries, nor had migratory strategies been described or 

spawning habitats identified. Telemetry tracking and repeated 

recapture of telemetered individuals over several years have 

been instrumental in providing insight into the reproductive 

behavior and ecology of pallid sturgeon (DeLonay and others, 

2009). Presently (2015) we know that wild and hatchery-origin pallid sturgeon are surviving, growing, attaining reproductive maturity and spawning in the Missouri River. Gamete 

development requires several seasons in pallid sturgeon, and 

spawning likely occurs every 1 to 3 years for males and 2 to 

5 years for females. Atresia resulting from disrupted reproductive development and the failure of gravid females to release 

eggs is more common in the upper study section of the Lower 

Missouri River, near Gavins Point Dam than in other study 

sections. Fecundity of telemetry females in this study section 

is lower as well, commonly 50 percent lower than telemetered 

females in the lower study section (DeLonay and others, 2012; 

DeLonay and others, 2014).

Pallid sturgeon have the capacity to migrate long distances upstream to spawn and females spawn at the apex of 

their migration (DeLonay and others, 2009; DeLonay and 

others, 2010; DeLonay and others, 2012; DeLonay and others, 

2014). Female pallid sturgeon exhibiting complex or disrupted 

upstream migration patterns tend to spawn later than females 

exhibiting the more typical migration pattern or may fail to 

spawn altogether. This behavior is especially notable in the 

upper study section of the Lower Missouri River, downstream 

from Gavins Point Dam and in the Upper Missouri and Yellowstone Rivers. Male pallid sturgeon exhibit more complex 

migratory patterns, perhaps because they are actively seeking 

suitable mates or attempting to spawn at multiple locations 

during the spawning period. Migrating pallid sturgeon in the 

lower study section of the Lower Missouri River migrate 

along inside bends, possibly to reduce energy expenditure 

during spawning by avoiding high velocities in the main channel. Pallid sturgeon in the upper study section of the Lower 

Missouri River, and Upper Missouri and Yellowstone Rivers 

do not have to contend with the high velocities similar to those 

in the lower study section of the Missouri River, and their 

migration pathways are less constrained. Reproductive pallid 

sturgeon in the Lower and Upper Missouri Rivers use constructed (Lower) and natural (Upper) side channel habitats in 

their upstream migrations.

Pallid sturgeon spawn in late-April through May on the 

Lower Missouri River, and in mid-June through early July on 

the Upper Missouri and Yellowstone Rivers when temperatures exceed 16–18 °C (Fuller and others, 2008; DeLonay 

and others, 2009; DeLonay and others, 2010; DeLonay and 

others, 2012; DeLonay and others, 2014). The distribution of 

spawning locations derived through intensive telemetry tracking indicates that pallid sturgeon are capable of spawning in 

most reaches of the main-stem Missouri River under a wide 

variety of conditions. Spawning also occurs in select tributaries, including the Platte and Yellowstone Rivers (DeLonay and 

others, 2014). Spawning habitat in the Lower Missouri River 

is characterized by deep, relatively fast and turbulent flow, on 

the outside revetted bends. Under the current (2015) management of the Lower Missouri River, this habitat is common 

and widespread. Pallid sturgeon on the Upper Missouri and 

Yellowstone Rivers spawn on gravel patches interspersed with 

compacted sand in deep, relatively fast flow. This habitat is 

presumed to be relatively rare on the Lower Missouri River. 

Sampling resulted in the collection of dispersing free-embryo 

pallid sturgeon on the Upper Missouri River in 2011, and the 

Yellowstone River in 2012. These collections document that 

conditions in those segments are suitable for the fertilization, 

survival, and hatch of pallid sturgeon eggs and embryos.

Data collected over several years on telemetered pallid 

sturgeon with known reproductive histories have revealed patterns of behavior. Repeated patterns of habitat use have been 

documented for male and female pallid sturgeon. Individual 

pallid sturgeon have been documented migrating to the same 

section of river to spawn with surprising affinity in the Lower 

Missouri River. These individuals tend to return downstream 

to a previously occupied bend or habitat patch following 

migration indicating a well-developed sense of spatial awareness in a highly altered open river system. Additionally, telemetered pallid sturgeon of both sexes have been documented 

migrating upstream in the Lower Missouri River during the 

fall before the initiation of a spring spawning migration, a 

behavior that has not been described in the Upper Missouri or 

Yellowstone Rivers.

Several reproductive abnormalities have been observed in 

shovelnose and pallid sturgeon collected in the Lower Missouri River (DeLonay and others, 2009). Intersex individuals 

with hermaphroditic gonads (either testis with developing eggs 

or ovary with small patches of testicular tissue) have been 

documented. Other abnormalities also have been observed, 

including individuals with one testicular lobe and one ovarian 

lobe, or individuals missing a lobe altogether, as well as teratomas (DeLonay and others, 2009). These observations led to 

the hypothesis that contaminants and water quality may have a 

role in diminished reproduction of pallid sturgeon.

Information Gaps

Although knowledge of pallid sturgeon spawning ecology and behavior has increased, many basic aspects remain 

unknown. Despite documentation of spawning across a broad 

geographic extent, it remains unclear whether it is occurring at 

appropriate locations, times, and under conditions that result 

in viable progeny. Diminished spatial and temporal spawning 

synchronicity would provide flexibility for pallid sturgeon 

to select suitable spawning habitat; conversely, spawning at 

many locations, distributed across a large geographic extent 

and for an extended time period, could serve to decrease the 

probability of finding suitable mates, and potentially encourage hybridization. Because no information is available on 
State of Scientific Understanding of Pallid Sturgeon Ecological Requirements and Implications for River and Species Management 103

spawning habitat associations or habitat choice in a pristine, 

unaltered river, it is unknown whether or not the adequate 

spawning habitat of the pallid sturgeon is available under current (2015) management of the Missouri River.

Extremely high discharges during 2011 provided insights 

to pallid sturgeon responses to rare flood events, but also 

raised many questions. The fact that sturgeon uncharacteristically migrated up the Upper Missouri River, formed aggregations, and spawned (DeLonay and others, 2014) supports the 

hypothesis that sturgeon will respond to flow pulses when 

provided. But it is not known what specific combination of 

environmental factors (discharge, water temperature, turbidity) were responsible and whether functional flow pulses are 

within operational constraints of the Missouri River reservoir 

system.

Record high releases from Gavin Point Dam also 

occurred in 2011 and affected pallid sturgeon populations on 

the Lower Missouri River. Although flows came too late to 

alter migration and spawning, pallid sturgeon were found on 

and adjacent to inundated floodplains (DeLonay and others, 

2014). Recaptured pallid sturgeon also demonstrated rapid 

increases in weight during 2011, but reexamination of the 

same individuals a year later indicated that much of the gains 

accumulated during the 2011 flood were lost after the drought 

of 2012. The loss in weight was not attributable to changes in 

gonad associated with spawning. The extent to which pallid 

sturgeon would exploit naturally inundated habitats during 

flood events or whether increased growth potential would 

be realized from greater access to the floodplain is not well 

established.

Pallid sturgeon on the Lower Missouri River are growing and do not appear to be starving, but the relation between 

forage availability and growth potential, condition, age at 

first reproduction, fecundity, and spawning periodicity is not 

known. Pallid sturgeon forage fish populations, consisting 

dominantly of native, turbid-adapted cyprinids, have declined 

substantially since the closure of the main-stem dams, and it is 

possible that there is a link between decline of forage species 

and pallid sturgeon reproductive condition. Additionally, the 

cause of intersex, how intersex develops, and the severity of 

intersex on reproductive behavior and viability are unknown.

Tracking of pallid sturgeon has demonstrated some 

spawning site fidelity, suggesting a role of geographic specificity in creating and maintaining genetic population structure. In 

the presence of strong site fidelity or natal affinities, management actions to benefit spawning and early life stages of 

pallid sturgeon should be aligned with where on the landscape 

spawning is occurring or can be successful. A high degree 

of affinity by a large river predator outside of the spawning 

period suggests the possibility of limitations on population 

density and carrying capacity in highly altered habitats with 

few patches of suitable habitat and limited prey availability. 

The carrying capacity for adult pallid sturgeon in contemporary altered river segments or under historic unaltered conditions is unknown.

Information Needs

Recent studies have documented what is possible in range 

of movement, habitat use, and behavior of pallid sturgeon. 

However, there is much to be learned and quantified about 

what conditions are necessary for pallid sturgeon to thrive and 

to sustain viable populations. A more robust understanding 

of basic demographic parameters, including optimal growth 

and condition, age of first reproduction, sex ratios, size of 

reproductive population, fecundity, and spawning success 

are essential to assess current (2015) population status and 

forecast population trends. Developing functional relations 

between these parameters and management actions is critical 

for monitoring species response and progress toward recovery. 

Defining where on the landscape and the spatial range within 

which critical species functions occur is fundamental to devising strategies for implementation of recovery actions, including connectivity with tributaries and the Mississippi River. 

Such efforts will help define the functions of habitat used by 

these fish and may provide insight into the maintenance of the 

rangewide genetic structure of the population.

More information is needed to quantify what characteristics comprise quality adult habitat. Restoring or engineering 

quality habitat requires an understanding of how sturgeon use 

habitat, forage, and spawn at a very fine scale. For example, 

habitat assessments on the Mississippi River have demonstrated the spatial association of pallid sturgeon with wing 

dikes (Koch and others, 2012). However, because of the strong 

hydraulic effects that wing dikes have on velocity gradients 

and local sediment transport, habitats around wing dikes are 

extremely diverse (Jamieson and others, 2009; Reuter and 

others, 2009; Jamieson and others, 2011), and without detailed 

tracking and habitat assessment at the scale of an individual 

fish it is difficult to identify specific habitat characteristics 

being exploited by sturgeon. Moreover, the predominant use 

of dikes by sturgeon cannot be assumed to indicate that dikes 

represent optimal habitat (as opposed to best available), nor 

can it be ruled out that use of dike fields result from avoidance 

of other habitats, such as the navigation channel. Our experience and that of others indicate that pallid sturgeon use habitat 

in complex ways, commonly orienting to bedforms or other 

hydraulic features. Understanding how pallid sturgeon perceive, and benefit from complexity is key to evaluating pallid 

sturgeon habitat quality.

Early Life-Stage Limitations—Spawn, 

Fertilization, Hatch, Drift

Although considerable uncertainties persist about the role 

of reproductive adults in recruitment failure, it has been recognized that pallid sturgeon research needs to shift emphasis to 

also consider recruitment failure in early life stages (Quist and 

others, 2004; Bergman and others, 2008). Early life stages as 

embryos, free embryos, and exogenously feeding larvae typically are highly susceptible to mortality.
104 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

State of Understanding

The period of spawning through the first year of life 

is known to be critical in determining year-class strength, 

recruitment, and population growth in sturgeon (Nilo and 

others, 1997; D’Amours and others, 2001; Parsley and others, 

2002). As is typical for most sturgeon, little information is 

available on survival and mortality rates of pallid sturgeon 

during the early life stages; however, mortality is likely high 

for young pallid sturgeon based upon inferences from other 

species. Field studies of lake sturgeon (Acipenser fulvescens)

resulted in estimates of mortality rates of 90–98 percent during the exogenous-feeding and larval age-0 life stage (Caroffino and others, 2010a). Moreover, the authors determined 

that mortality from the egg through age-0 life stage was 

99.925–99.984 percent. Stellate sturgeon (Acipenser stellatus) in the Volga River (not shown) have an estimated mean 

survival rate of 2.5 percent between the pre-larva (5 dph) 

and fingerling (50–60 dph) stages, but survival from the egg 

to fingerling stages averaged 0.75 percent (Usova, 2009). A 

study in the Mississippi River determined that undifferentiated Scaphirhynchus spp. during the age-0 life stage exhibited 

instantaneous mortality rates of 0.25–0.64 (Phelps and others, 

2010b). Whereas pallid sturgeon-specific survival information is lacking for the age-0 life stage, inferences on survival 

through the first winter of life are becoming available from the 

pallid sturgeon population augmentation and monitoring programs. Rotella (2012) reported that hatchery-produced age-0 

pallid sturgeon in the Upper Missouri and Yellowstone Rivers 

exhibited survival rates of 78–79 percent between the September release period and capture period the following April.

Survival estimates from Caroffino and others (2010a) 

and Rotella (2012) can be used to gain insight into potential 

dynamics of pallid sturgeon populations through the first year 

of life. For example, based on a mortality rate of 99.925–

99.984 percent from the egg through age-0 life stages, about 

6–30 age-0 pallid sturgeon would survive through the first 

growing season from a spawning event involving 40,000 eggs. 

Of these age-0 survivors, an estimated 5 to 23 individuals 

would survive through winter and be present as age-1 individuals based on an over-winter survival rate of 78 percent. The 

known presence of multiple gravid females and documented 

spawning in the Upper and Lower Missouri River (Fuller and 

others, 2008; DeLonay and others, 2009; DeLonay and others, 

2010; DeLonay and others, 2012) in combination with survival projections to age-1, suggest that young pallid sturgeon 

should be present. However, evidence of wild-produced pallid 

sturgeon progeny surviving through the first year of life is 

lacking throughout the species’ range. These results imply that 

spawning success and mortality during the first year of life are 

among the primary drivers for lack of recruitment throughout 

the species’ range.

Available information detailing the early life stages of 

pallid sturgeon, including fertilization rates, time to hatch, percent of embryos that hatch, drifting behavior, yolk absorption, 

and first feeding, is known mostly from laboratory studies 

and hatchery propagation efforts. The end of the drifting 

period coincides with the onset of feeding and filling of the 

swim bladder, which occurs at about 11 dph. Information on 

drift velocities from the release of artificially propagated free 

embryos for field-based studies in the Upper Missouri River 

suggests that, in general, free embryos drift in the thalweg, 

and slightly slower than mean water velocities. Calculations 

based on these estimated drift velocities indicate that sturgeon 

larvae have the potential to drift long distances and require 

similarly long segments of free-flowing river to complete the 

ontogenetic development to benthically oriented, exogenously 

feeding larvae.

The protracted free-embryo dispersal period for pallid 

sturgeon suggests that larvae spawned throughout much of 

the Lower Missouri River may drift into the Middle Mississippi River (DeLonay and others, 2009), and larvae spawned 

in the Yellowstone and Upper Missouri Rivers will likely 

drift into the upper reaches of Lake Sakakawea (Braaten and 

others, 2008; Braaten and others, 2012a). Studies of genetics, 

microchemistry, and stable isotopes may provide insight into 

longitudinal and latitudinal distribution. In the Lower Missouri River, the present-day mean river velocities are higher 

and distributions of velocities substantially different than the 

historical condition, and early analyses indicate that the spatial 

and temporal scale of free-embryo dispersal, and the sequence 

and arrangement of early life-stage drift and settling habitat 

may be altered. Laboratory studies examining first feeding and 

time to starvation in pallid sturgeon free embryos suggest that 

early food availability during the transition to exogenous feeding is critical to survival. The existence of imprinting in young 

pallid sturgeon is unknown, but altered early dispersal patterns 

could be manifest in altered adult spawning migrations and 

consequent changes in population dynamics.

Information Gaps

Little is known about egg deposition, fertilization, and 

retention in spawning substrate outside the controlled setting 

of laboratories and little direct evidence exists concerning 

adaptive nature of drift strategies (immediate compared to 

delayed drift), ontogenetic development during the free drift 

phase, and the “settling” processes in the Missouri River or 

its tributaries. Due in large part to low densities of reproductive adults and the challenges of statistically sampling for 

larvae across the diverse habitats of the Missouri River, little 

is understood about the distribution of larval sturgeon between 

the main channel and adjacent channel border habitats or the 

value of these habitats to free embryos. Moreover, little is 

known about the behavior of drifting free embryos as they 

transition to benthic habitats. In addition, little is known about 

other threats that may affect dispersing free embryos, including the potential for mortality associated with the numerous 

water withdrawals and intakes along the Missouri River, 

increased predation with reduced turbidity in the contemporary channel, and reduced growth and development from 

altered thermal regimes below main-stem dams.
State of Scientific Understanding of Pallid Sturgeon Ecological Requirements and Implications for River and Species Management 105

Early life stages are generally considered the most sensitive to contaminants. Exposure may occur during maternal 

egg development or during incubation while in contact with 

water or sediments (Wildhaber and others, 2007a; Buckler, 2011). Although pallid sturgeon have been successfully 

hatched and reared in captivity, few data exist on the tolerance 

of these early life stages to specific environmental stressors 

and contaminants (Wildhaber and others, 2007a). The relative 

susceptibility of early life-stage pallid sturgeon to predation in 

the presence of native and introduced predation likely plays a 

role in early survival, but the relative importance of predation, 

especially in the altered contemporary river in comparison to 

other sources of mortality is not known.

Information Needs

Understanding of egg deposition, and adhesion would 

provide insight on whether substantial, suitable, and adequately conditioned spawning substrates exist in the current 

(2015) Missouri River or whether these conditions are sensitive to flow or channel engineering. Improved understanding of typical egg drift distances, egg settling processes, and 

settling habitats of larval pallid sturgeon would provide useful 

guidance for placement and design of channel-restoration projects that are intended to provide spawning and corresponding 

downstream rearing habitat. Improved understanding of drift 

dynamics would document whether flow or channel re-engineering designed to decrease mean velocity and increase drift 

retention would be effective for increasing recruitment. Understanding transport, dispersion, and fate of pallid sturgeon eggs 

and larvae would help to determine if they successfully drift 

into habitats conducive to hatch, survival, feeding, and growth. 

Examining differences in early dispersal and development 

among populations of pallid sturgeon also would be important 

in the design of effective monitoring programs to evaluate 

annual reproductive success.

Young-of-Year to Juvenile

Compared to earlier life stages, more information exists 

on YOY to juvenile stages because of studies on propagated, 

hatchery-origin fish. These life stages also are considerably 

less difficult to sample with conventional gears compared to 

eggs, free embryos, and exogenously feeding larvae.

State of Understanding

The factors most likely to affect juvenile sturgeon are 

human exploitation, availability of food resources, habitat 

quality, predation, and competition (Wildhaber and others, 

2007a, 2011a). The well-documented dietary shift during 

juvenile life stage, from consuming mainly invertebrates 

to consuming mainly fish, is thought be important in pallid sturgeon growth and lends support to the hypothesis that 

declines in forage fish (for example, Macrhybopsis chubs) 

may be associated with pallid sturgeon declines (Gerrity and 

others, 2006). Emerging information on habitat use of age-0 

Scaphirhynchus (undifferentiated shovelnose and pallid 

sturgeon) indicates that they are found associated with wing 

dikes and rootless dikes with bottom velocities of 0.5–0.7 

m/s and depth generally greater than 1.0 m (Ridenour and 

others, 2011). The effects of predation on juveniles are 

unknown. Flathead catfish have consumed small juveniles 

(40–50 mm fork length) in proportion to their availability 

in laboratory studies while avoiding larger sturgeon (French 

and others, 2014). Shovelnose sturgeon and pallid sturgeon 

have been documented in the stomachs of flathead catfish in 

the Lower Missouri River (Kirk Steffensen, Nebraska Game 

and Parks Commission, oral commun., 2015). The extent to 

which predation by native or nonnative predators is enhanced 

in the contemporary altered Missouri River is unknown and 

requires further study.

Information Gaps

There is little information on habitat selection—habitat 

use compared to availability—by age-0 and juvenile pallid 

sturgeon. Further, it is unknown whether preferred habitat of 

YOY and juvenile pallid sturgeon is available under current 

(2015) management of the Missouri River. If juvenile pallid 

sturgeon need to select habitat conditions, including temperature and water quality that vary from those present in the main 

channel, the options in the altered river are limited. Differences between juvenile pallid sturgeon and shovelnose sturgeon habitat use have not been described, and the nature and 

extent of competition among the species is not known. Information on growth rates of pallid sturgeon in the wild is limited 

due to the limitations in aging methodologies (Wildhaber and 

others, 2007a). Data on juvenile pallid sturgeon growth are 

available for hatchery progeny stocked in the Missouri River, 

and observed rates have been described as acceptable (Shuman and others, 2011). However, interpretation of the data is 

limited by a lack of knowledge of the potential for growth of 

pallid sturgeon in unaltered, quality habitat, and the lack of 

information for older pallid sturgeon, which must transition to 

piscivory before reaching reproductive maturity.

Hypotheses about prolonged drift of pallid sturgeon free 

embryos suggest that successful larvae will disperse downstream far from spawning sites. The strategy for upstream 

migrations by pallid sturgeon is only partially described, however, and only for the reproductive adults. Reproductive adult 

migrations described by CSRP to date have been far shorter 

than the estimated drift distances for free embryos. This inconsistency may be due to several life history traits, acting alone 

or in combination, including shorter downstream dispersal by 

free embryos than currently (2015) hypothesized, multistep 

migrations for a return to the spawning location beginning 

as early as the juvenile stage, and shorter downstream postspawn migrations by adults relative to free-embryos dispersal 

distances, which result in shorter subsequent spawning migrations. The geographic extent of the river used through the peak 
106 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

of migration to the downstream limit of juvenile dispersal is 

unknown, and the strategy used by pallid sturgeon to migrate 

and disperse also is poorly understood.

Information Needs

Understanding the distribution and dispersal of juvenile 

pallid sturgeon would provide insight on habitat preference 

that would provide useful guidance for placement of channelrestoration projects that are intended to provide rearing habitat. Understanding of optimal food items, and habitat requirements and flow conditions required by these species, may 

provide guidance to increase or improve these conditions in 

the context of the current (2015) Missouri River. Additionally, 

understanding the age, growth and survival of juvenile pallid 

sturgeon in the wild is essential for assessing current (2015) 

population status and forecasting population trends (Wildhaber 

and others, 2007a).

Role of Management Actions

Management actions for recovery of pallid sturgeon on 

the Missouri River have emphasized hatchery population 

augmentation, flow regime changes, and re-engineering of 

the previously channelized Missouri River. The challenge to 

recovery strategies has been how to use the available scientific 

information to determine the most effective investments in 

these three actions. Understanding is complicated by spatial 

variation among river segments and interactions of management actions.

Population Augmentation

Whereas population augmentation practices are helping to avoid extirpation and maintain the species, successful 

spawning and natural recruitment are required for long-term 

pallid sturgeon recovery. Hatchery-origin pallid sturgeon are 

surviving, growing and reaching sexual maturity; however, 

more information is needed to evaluate their contribution to 

reproduction, recruitment and recovery, especially in light of 

the emerging genetic evidence of the rangewide population 

structure of the species. Into the foreseeable future, the conservation augmentation program will have the greatest effect 

on pallid sturgeon population growth, genetic diversity and 

viability. Population augmentation or the recovery of endangered species carries risks that may be minimized by methods 

that do the following:

• Select appropriate broodstock,

• Develop breeding protocols that assure even, consistent 

contribution of diverse matings,

• Implement hatchery practices that reduce the incidence 

and transmission of disease to wild populations,

• Implement population augmentation strategies that 

preserve contributions of wild fish and natural genetics 

structure on the landscape,

• Implement stocking strategies that emphasize adaptation to local environments and preservation of imprinting opportunities for natal areas (such as, streamside 

rearing or egg and free-embryo repatriation) to 

increase fitness, reduce hatchery selection, and enhance 

the return of spawning adults to appropriate spawning 

sites,

• Implement robust marking protocols and genetic analyses to monitor performance and assess risks, and,

• Administer complete, accurate record keeping systems 

to prevent errors and document success.

In addition, there is a recognized symbiosis between the 

conservation augmentation program and sturgeon research. 

Hatcheries that consistently can produce high quality reproductive products and progeny are invaluable partners to support focused, controlled laboratory studies of pallid sturgeon 

critical spawning requirements and early life history stages. 

Although the long-term use of captive broodstock is strongly 

cautioned, the anticipated limited use of captive adults to 

produce progeny for population augmentation in the Yellowstone and Upper Missouri Rivers requires fundamental 

research to understand long-term effects of hatchery culture 

on broodstock viability and to develop methods to improve the 

reliability of induction, fertilization, and hatch success, tools 

for the identification and prevention of sturgeon diseases, and 

measures to improve and evaluate the quality and survivability 

of hatchery progeny.

Flow Regime

The hypothesis that spawning behavior relates to environmental cues—thresholds or episodes of variation in discharge, 

temperature, turbidity, conductivity, or factors such as day 

length or moon phase—has been pervasive in sturgeon literature (Paragamian and Kruse, 2001; Forsythe and others, 2012; 

Goodman and others, 2012). Sturgeon scientists have been 

challenged to isolate which interacting external environmental 

conditions might be instrumental in triggering suspected fish 

behaviors, including pre-migration aggregations, migration, 

and spawning. The ability of field-based research to infer 

causal relations has been limited by extreme year-to-year 

hydrologic and climatic variability, the relatively small size of 

intentional spring pulsed releases (fig. 29), and small numbers of subject fish. Pallid sturgeon spawn in the spring and 

early summer during periods of increasing day length. Water 

temperature consistently exerts a threshold affect for spawning at 16–18 °C. Moreover, pauses and reversals in upstream 

migrations have been associated with cold weather fronts that 

create a transient decrease in water temperature (DeLonay 

and others, 2009). From 2005 to 2012 on the Lower Missouri 
State of Scientific Understanding of Pallid Sturgeon Ecological Requirements and Implications for River and Species Management 107

River no obvious relations between flow pulses and fish movements and spawning behaviors have been apparent.

Although pallid sturgeon migration and spawning on the 

Lower Missouri River do not appear to be linked consistently 

to discharge conditions in the Lower Missouri River, it does 

not follow that discharge is not important to overall spawning 

success. Linkages have been noted between changes in water 

temperature and migration rate or direction (DeLonay and 

others, 2010); to the extent that water temperature varies with 

discharge, flow events could cause disruptions in migration, 

and disrupted migration patterns of female pallid sturgeon in 

reproductively ready condition have the potential to reduce 

spawning success or trigger deposition in suboptimal habitats 

or in inappropriate conditions. Evidence of linkages between 

flow regime and sturgeon migration and spawning are clearer 

in the Upper Missouri River where typical movement patterns 

were disrupted during high flows in 2011. In a typical year, 

pallid sturgeon predictably move from the Missouri River into 

the Yellowstone River in the spring with increasing flow and 

temperature, leaving once spawning is complete and discharge 

declines. Similarly, shovelnose sturgeon move from the Yellowstone River into the Tongue and Powder Rivers (fig. 2) 

to spawn with increasing temperature and discharge, leaving 

after spawning is complete. In 2011, extreme discharge in the 

Upper Missouri River was associated with pallid sturgeon 

electing to move up the Missouri River in atypical numbers, resulting in aggregations and successful spawning. The 

contrast in responsiveness to flow regime by adults in the two 

study sections is a valuable comparison that warrants further 

study.

Presently available information on reproductive responses 

to intentional pulsed-flow releases documents the lack of 

response to small releases on the Lower Missouri River up 

to 2011 (Doyle and others, 2011) and substantive, but unreplicated responses to extreme forced releases in 2011. Little 

information exists to evaluate responses to intermediate flow 

releases except for investigations of reproductive responses 

in the lower study section of the Lower Missouri River where 

uncontrolled flow pulses are confounded with varying water 

temperature and interacting pulses. The possibility exists that 

pallid sturgeon would respond to intentional flow pulses of a 

magnitude that have not yet been implemented.

The extent to which flow regime affects spawning of 

pallid sturgeon, and therefore the initiation of the start of 

the drifting phase of larval development, remains unclear at 

this time. A more detailed understanding of egg deposition 

is necessary to fully evaluate whether substrate conditions at 

spawning sites may be improved with flow management. Flow 

regime likely affects where larvae settle, and thus the location 

where the juvenile life stage begins. Flow regime also may 

affect habitat availability to juvenile and adult pallid sturgeon, 

as well as affect complex processes such as food transport and 

availability and competition in those habitats. The efficacy of 

flow regime in influencing habitat availability and food-web 

processes is interdependent with channel morphology and how 

it is being re-engineered as a restoration action.

Channel Engineering

Spawning habitat.—Studies on spawning habitat dynamics have reported that habitat patches selected for spawning by 

fish in the Lower Missouri River are dominantly on outside, 

revetted bends in the deepest, fastest, and most turbulent 

water. Hydroacoustic maps and images document that these 

sites have steep slopes underlain by revetment adjacent to 

actively migrating sand dunes. Although these sites are abundant in the Lower Missouri River and would appear not to be 

limiting to reproduction, questions remain about the fate of 

released eggs because of the steep slopes, angular revetment 

rock, unknown interstitial space in the revetment, high velocities and turbulence, and potential for burial if eggs end up at 

the base of the revetment slope. Hydraulic modeling of these 

patches has indicated that depths and velocities are not sensitive to discharge because of the simple channel morphology. 

Geomorphic monitoring, however, has indicated that because 

the sand bed material is always in transport, there is potential 

for bedload transport to modify these patches, either before 

spawning to scour sand from spawning substrate, or during 

and after spawning when sand substrate could bury eggs.

Increased intensity of spawning assessment in the Yellowstone River in 2011 and 2012 has presented an alternative 

view of spawning habitat and its relation to fish reproductive behaviors. Spawning habitats on the Yellowstone River 

downstream from Intake Dam appear to be more discrete and 

controlled by the presence of patches of gravel within a sanddominated channel. Because they are discrete, we hypothesize 

that the Yellowstone River patches may be more effective in 

attracting aggregations of reproductive fish compared to the 

nearly continuous revetment on the Lower Missouri River, 

which may operate to spread spawning aggregations out along 

the river. This hypothesis needs additional exploration.

The sedimentological and hydraulic conditions of habitat 

patches also have a bearing on how hatched larvae are introduced into their environment. A key question is whether larvae 

drift immediately after hatch or instead spend some time in 

substrate interstices before drifting. Field and laboratory data 

presented in this report support either hypothesis, and it is not 

known whether either behavior would lead to greater survival 

from hatch to age-0. The two hypotheses may not be mutually 

exclusive; instead, there may be a continuum from immediate 

drift to interstitial hiding with varying probability of survival 

depending on drift distance and habitat availability when the 

free embryos transition to exogenous feeding.

An increased understanding of the importance of finescale conditions at spawning habitats to successful fertilization, incubation, hatch, and initial drift of pallid sturgeon 

embryos has prompted the development of new hypotheses. 

Laboratory experiments can provide critical insights into these 

processes, albeit the range of conditions in laboratories cannot 

replicate field conditions. Experiments based on testing how 

well embryos deposited on artificial substrates survive and 

hatch will be useful to understand the effect of this aspect 

of channel engineering on spawning success. If additional 
108 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

research confirms the importance of fine-scale processes in 

spawning habitats, quantitative hydraulic and sedimentological data from reference sites in the Yellowstone River may 

provide guidance for restoration designs on the Lower Missouri River.

Rearing and feeding habitat.—It has been reported that 

channel re-engineering can increase the amount of shallowwater habitat, as well as habitat complexity (Jacobson and 

Galat, 2006); however, the linkages to larval retention, 

survival, and growth of the early life stages of pallid sturgeon 

have not yet been established. Design decisions for re-engineering actions intended to slow drift or provide greater rearing habitat would necessarily depend on correct diagnosis that 

these factors are, in whole or in part, responsible for recruitment failure. Drift models indicate the role of mean velocity 

in downstream transport of free embryos; mean velocities 

could be slowed through decreased discharges or by channel re-engineering that increases hydraulic radius (width and 

topographic diversity). In addition, the probability that free 

embryos are transported into and retained in channel-margin 

habitats is theoretically amenable to channel re-engineering 

that would increase cross-channel secondary currents in bends 

or channel expansions. Considerable uncertainty persists, however, about what channel-margin habitats should look like to 

optimize survival and growth of age-0 and juvenile sturgeon, 

and where along the river such habitats would most contribute 

to population growth.

In addition to a hypothesized function as rearing habitat, 

increased habitat diversity in channel-margin habitats has 

been hypothesized to increase productivity and food production, with eventual effects on pallid sturgeon growth and 

survival. Channel engineering and bank stabilization have 

reduced the interaction of the river with the floodplain, simplified channel form (including limiting large woody debris 

retention, a key invertebrate habitat), and limited functional 

processes related to primary and secondary productivity. 

Direct functional relations between productivity, food availability, and community composition that can predict changes 

in parameters that affect population growth, although intuitive, have not yet been documented or quantified for pallid 

sturgeon at any life stage.

Nevertheless, correlations suggest a linkage may exist. 

Longitudinal differences in female pallid sturgeon fecundity 

have been documented in this report and others (Albers and 

others, 2013), leading to the hypothesis that recruitment failure 

may be due, at least in part, to adult fish having insufficient 

nutrition to produce the numbers of gametes needed for the 

population to grow. Documented declines in populations of 

known pallid sturgeon prey fish (Galat and others, 2005a) also 

are broadly correlative with recruitment failure, lending support to the hypothesis that food may be limiting. These associations point to a need to continue to develop diet energetics 

models for juvenile and adult fish (Gerrity and others, 2006), 

and to consider population dynamics of prey fish like Macrhybopsis chubs. If food availability is determined to be an 

important factor in growth and reproductive potential of pallid 

sturgeon, restoration of habitats used by prey fish may a useful strategy. However, establishing a chain of causality from 

physical habitat, to prey-fish populations, to use of prey-fish in 

sturgeon diets, to increased sturgeon fecundity, and eventually 

to pallid sturgeon population growth presents a considerable 

scientific challenge. Effective restoration of channel-margin 

habitats specifically to increase food availability also would 

require understanding where in the geographic range and life 

cycle of the pallid sturgeon food might be most limiting. This 

would require improved understanding of movement and habitat affinities of juveniles and reproductive adults.

Synergies

Modifications of flow regime and channel engineering are 

not independent or isolated. Reducing flows from main-stem 

dams during high tributary flows could have beneficial results 

for sturgeon responsive to water quality and temperature. A 

renewed appreciation for the potential importance of select 

tributaries for feeding or spawning may suggest increased 

opportunities or added flexibility in management strategies to 

aid pallid sturgeon. Similarly the Mississippi River likely has a 

substantial effect on the survival of early life-stage pallid sturgeon spawned in the Lower Missouri River. Eventual recruitment of pallid sturgeon to the Missouri River adult spawning 

population may be limited by habitat conditions in the Middle 

Mississippi River.

Other factors outside of the direct effect of Missouri 

River management also may affect pallid sturgeon growth 

and survival. Among these, contaminant effects may be the 

most important to understand in context of other threats. 

Although the threat of legacy chemical loads (DDT, PCB) is 

diminishing and likely localized, the potential for persistent 

and widespread exposure to endocrine disrupting chemicals 

from agricultural and waste-water treatment sources is present 

throughout the Midwest and the Missouri River Basin (Kolpin 

and others, 2010; Wiener and Sandheinrich, 2010; Blevins, 

2011; Larsen and others, 2013).

Strategies for Addressing Key Information Gaps

Early studies with pallid sturgeon struggled with the 

overall rarity of a poorly known, endangered species against 

the backdrop of their existence in large, turbid rivers. The 

development of technologies for better sampling and monitoring of pallid sturgeon populations rapidly advanced scientific 

knowledge. Informed by results of previous studies, and with 

opportunities afforded by increased number of pallid sturgeon 

available through population augmentation, future hypotheses 

for study can be more focused and directed towards management and recovery objectives. A measured approach to science 

investment would be to develop a diverse portfolio with 

complementary long-term monitoring and hypothesis-driven, 

focused studies that integrate field and laboratory perspectives. 

We believe the following are high science priorities:
Conclusions—Synthesis of Reproductive Ecology of the Pallid Sturgeon in the Missouri River 109

• Continuation of long-term monitoring of reproductive 

cycles, reproductive movements, growth, and survival 

of telemetry tagged adults. These studies are essential to 

further define the life-ranges of pallid sturgeon subpopulations and how those sub populations interact with 

spatially variable habitats along the river. The studies 

provide the basis for determining where to invest in 

different channel-re-engineering actions to best support 

species’ needs. Assessment of reproductive movements 

will continue to provide insights into the role of environmental variables in life-stage transitions.

• Increased emphasis on focused, complementary field 

and laboratory studies of factors influencing early life 

history. These studies are essential to understand how 

substrate conditions and local hydraulics may affect 

survival through egg deposition, fertilization, hatch, 

and initial drift; the studies would provide design 

parameters for re-engineering channels to restore 

spawning habitat. Field studies of physical processes 

affecting larval drift and retention would provide a 

template for sampling of larvae and the physical understanding needed to design channels to enhance retention. Early life history studies can use comparative 

studies among least and highly altered river systems to 

advantage.

• Implement studies to resolve role of food limitations 

in growth, survival, and reproductive condition. These 

studies are necessary to establish whether linkages 

exist between pallid sturgeon populations and food 

production, especially to determine how restoration of 

channel-margin habitats may affect pallid food supply. 

These studies would use assessments of fitness and 

fecundity derived from the Pallid Sturgeon Population Assessment Program and continued monitoring of 

the telemetry population, combined with diet studies 

and increased energetics modeling to determine if the 

forage base is sufficient to maintain reproduction in the 

population.

• Conduct monitoring, field, and laboratory studies to 

produce information needed to parameterize quantitative models relating management actions to pallid 

sturgeon population responses. Effective use of quantitative modeling can aid in identifying uncertainty and 

prioritizing information needs. The development of 

population viability models can help to place information in the context of population growth and allow 

simulations or sensitivity analyses to direct resources 

towards critical life stages and factors limiting survival. Physical models that incorporate biological 

requirements or functions in the context of the engineered river environment provide powerful tools for 

communication and integrated management. Ideally, 

monitoring and research results should feed into a 

population dynamics modeling framework.

Conclusions—Synthesis of 

Reproductive Ecology of the Pallid 

Sturgeon in the Missouri River

Although substantial progress has been made by the 

Comprehensive Sturgeon Research Project (CSRP) and other 

researchers from 2005 to 2012 in understanding the reproductive ecology of the pallid sturgeon, in many ways the pallid 

sturgeon remains an enigmatic, poorly understood species. 

This is expected given the rarity of the species and its characteristic use of benthic habitats in deep, turbid rivers. Although 

there has been rapid progression in understanding of fundamental biology and habitat affinities (fig. 7), critical uncertainties in the existing science base confound many management 

decisions. There exists an acute need to move from observation to prediction, especially to provide predictive understanding of future prospects for the population given changing 

river management, land use, and climate. The objective of this 

report was to synthesize the state of the science as a precursor 

to moving to predictive modeling.

Landscape Scale Genetics

Present-day (2015) population dynamics and recovery 

actions play out within the fragmented Missouri and Mississippi River systems. Dams have created barriers to upstream 

migration and reservoirs may have created unsuitable habitats 

for dispersing larvae. As a consequence, the lengths of river 

and types of habitats available to pallid sturgeon have been 

severely altered. The Upper Missouri and Yellowstone Rivers 

subpopulations may have insufficient space to carry out its life 

cycle without substantial re-engineering to create additional 

drift distance. It is critical to establish the causal link between 

free-embryo dispersal and mortality to explore all possible 

restoration options. In the Lower Missouri River, closure of 

the main-stem dam system may have pushed the population 

downstream with unknown consequences for habitat availability and potential interactions with Mississippi River subpopulations. Recognition of genetic structure has clear implications 

for management of the Pallid Sturgeon Conservation and 

Augmentation Program, but also for how restoration activities are arranged along the river. If conservation of genetically 

structured pallid sturgeon populations with locally adapted 

traits is a high priority, restoration actions may be designed to 

minimize downstream dispersal by re-engineering the channel 

to decrease velocities and increase probability of retention in 

channel-margin habitats.

River Management and Population Dynamics

Landscape scale fragmentation and potential displacement of the naturally occurring genetic structure of the pallid 

sturgeon population set broadscale context for recovery of the 
110 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

species. Within that context, recovery requires understanding how river restoration and management decisions affect 

processes that, in turn, affect survival probabilities from one 

life stage to the next. Research has not identified a single 

biological or ecological constraint that appears to limit populations of the pallid sturgeon. With the present (2015) state of 

knowledge, many life stages and life-stage transitions cannot 

be ruled out as contributing to recruitment failure.

Pallid sturgeon have complex life histories, with discrete 

ontogenetic transitions, each with specific requirements that 

play out across a relatively large spatial and temporal scale. 

Addressing this complexity through management action on 

the landscape can be reduced to a series of simple guiding 

principles. Effective restoration of viable sturgeon populations 

requires unimpeded connectivity of substantial distances of freeflowing river, continuous alignment between habitat availability 

and life history requirements, sufficient availability of habitats, 

and adequate habitat quality to sustain survival and growth. 

Although the principles are simple, the information needed to 

incorporate these principles into management is substantial.

The 2000 and 2003 biological opinions presented the 

dominant hypotheses for recruitment failure that existed at that 

time. Emphasis was on the role of the flow regime, specifically spring flow pulses (“spring rises”), to condition spawning substrate and cue reproductive aggregations and migrations, and on the need for additional shallow-water habitat to 

serve as rearing habitat for age-0 to juvenile pallid sturgeon. 

Understanding from CSRP and other studies has broadened 

restoration perspectives to emphasize increased opportunities 

for upstream passage of migrating adults to provide greater 

habitat availability and to improve the functionality of the 

downstream array of habitats throughout the geographic extent 

of populations to accommodate free-embryo dispersal.

Spawning Habitat and Cues

The Comprehensive Sturgeon Research Project addressed 

the hypotheses related to spawning and spawning habitat by 

implementing directed research based on following tagged 

reproductive pallid sturgeon to spawning sites, quantifying the 

potential for environmental cues before, during, and after their 

migration, and applying concerted mapping and modeling 

efforts to quantify spawning habitat availability and dynamics. Studies on spawning habitat dynamics have determined 

that habitat patches selected for spawning by fish in the Lower 

Missouri River are dominantly on outside, revetted bends in 

the deepest, fastest, and most turbulent water. Increased intensity of spawning assessment in the Yellowstone River in 2011 

and 2012 has provided an alternative view of spawning habitat 

and its relation to fish reproductive behaviors in a more natural 

setting. Spawning habitat on the Yellowstone River downstream from Intake Dam is characterized by discrete patches 

of gravel within a sand-dominated channel, an arrangement 

that may be more effective in attracting aggregations of reproductive fish compared to the nearly continuous revetment on 

the Lower Missouri River.

The sedimentological and hydraulic conditions of habitat 

patches also have a bearing on how hatched free embryos are 

introduced into their environment. A key question is whether 

free embryos drift immediately after hatch or instead spend 

some time in substrate interstices before drifting. Field and 

laboratory data presented in this report support either hypothesis, and further study would aid in determining which would 

lead to greater survival from hatch to age 0. Hypotheses 

relating fine-scale conditions in spawning habitat to successful 

fertilization, incubation, hatch, and initial drift are challenging 

to test in the Missouri River. However, comparative research 

on spawning habitats in the Yellowstone River can provide 

hydraulic and sedimentological data that may be useful for 

restoration designs on the Lower Missouri River. In addition, 

laboratory experiments can provide critical and complementary insights into processes, despite their limitations in replicating field conditions.

The hypothesis that spawning behavior relates to environmental cues—thresholds or episodes of variation in discharge, 

temperature, turbidity, conductivity, or factors such as day 

length or moon phase—has been pervasive in sturgeon literature. Pallid sturgeon spawn in the spring and early summer 

during periods of increasing day length. Water temperature 

consistently exerts a threshold effect for spawning at 16–18 

°C. Moreover, pauses and reversals in upstream migrations 

have been associated with cold weather fronts that create a 

transient decrease in water temperature (DeLonay and others, 

2009). From 2005 to 2012 on the Lower Missouri River, no 

obvious relations between flow pulses and fish movements and 

spawning behaviors have been apparent.

These observations do not necessarily indicate that flow 

has no role in pallid sturgeon reproduction. Pallid sturgeon 

tracking at the Upper Missouri River–Yellowstone River 

confluence indicates that in most years, most telemetered 

pallid sturgeon migrate out of the Missouri River and into the 

Yellowstone River in the June–July timeframe in association 

with the spring pulse in the Yellowstone River. This pattern 

held consistently from 2004 to 2010, and in 2012. However, 

in 2011 when a high flow pulse with warm temperatures and 

high turbidity emanated from the Milk River, followed by 

record releases from Fort Peck Dam, 36–39 percent of the 

telemetered population migrated up the Upper Missouri River 

in a distinct anomaly (DeLonay and others, 2014). This supports the hypothesis that flow pulses can operate to cue pallid 

sturgeon reproductive behavior. It is important to note, however, that the hydrologic conditions in 2011 were extreme and 

the size of flow pulses in the Upper Missouri River resulted 

in record releases from Fort Peck Dam. Comparative and 

repeated studies would aid in resolving the cues or causative 

factors responsible for the observed response to altered flows 

(Carpenter, 1990).

Apparent reproductive failure in pallid sturgeon in the 

Missouri River may result from a lack of adequate numbers 

of spawning adults, poor survival of early life stages, or from 

emigration of dispersing free embryos out of the Missouri 

River, or through hybridization with shovelnose sturgeon. The 
References Cited 111

importance of the Mississippi River in pallid sturgeon recruitment in the Missouri River should be addressed. Hybridization 

occurs, but the rate of hybridization is unknown and the threat 

is poorly characterized in the Lower Missouri River. The factors responsible for an increased incidence of hybridization and 

introgression include low numbers of adults, barriers that fragment habitat and limit access to spawning locations, and alterations of habitat and flow that erode spatial and temporal separation between the two species. Each of these factors is present in 

the contemporary Lower Missouri River and may contribute to 

the current (2015) level of introgression. Which factor is most 

important is currently unknown and a comprehensive strategy 

to remediate the threat has yet to be formulated.

Free Embryo and Larval Dispersal, Retention, and 

Channel Morphology

Dispersal distance and characteristics of rearing habitat 

are also amenable to restoration and management actions. 

Decisions in investing in actions to slow drift or provide 

greater rearing habitat would necessarily depend on correct 

diagnosis that these factors are, in whole or in part, responsible 

for recruitment failure. Current velocities could be slowed 

through decreased discharges or increased channel hydraulic 

radius (width and topographic diversity). In addition, the probability that free embryos are transported into and retained in 

channel-margin habitats is theoretically amenable to channel 

re-engineering that would increase cross-channel secondary 

currents in bends or channel expansions. Considerable uncertainty persists, however, about what channel-margin habitats 

should look like to optimize survival and growth of age-0 and 

juvenile sturgeon, and where along the river such habitats 

would most contribute to population growth. A process-based 

understanding of how abiotic and biotic processes are linked 

in channel-margin habitats would provide improved guidance 

for channel re-engineering efforts to benefit pallid sturgeon.

Food Availability and Channel Morphology

Differences in female pallid sturgeon fecundity along the 

length of the Missouri River have been documented in this 

report and others. Although this phenomenon may be affected 

by natural latitudinal clines in species growth, it may also, at 

least in part, be affected by insufficient availability of forage 

to produce the greater numbers of gametes. Reduced gamete 

quality and fecundity would result in decreased individual 

lifetime reproductive output and poor survival of progeny. 

Declines in populations of known prey fish like Macrhybopsis

chubs (Galat and others, 2005a) also are broadly correlative 

with the pallid sturgeon population decline. This leads to the 

hypothesis that restoration of channel-margin habitat complexity would result in an increase in chub populations, and 

subsequently an increase in growth and fecundity of adult pallid sturgeon (Gerrity and others, 2006). Establishing a chain of 

causality from physical habitat, to prey-fish populations, to use 

of prey-fish in sturgeon diets, to increased sturgeon fecundity, 

and eventually to pallid sturgeon population growth presents a 

considerable scientific challenge. The challenge is not insurmountable. A detailed food web model coupled with physical 

and biological models informed by field and laboratory studies 

is needed to establish these critical linkages. Effective restoration of channel-margin habitats specifically to increase food 

availability would also require understanding where in the 

home range of the pallid sturgeon food is most limiting.

Future Information Needs

Scientific understanding of the ecological requirements 

of pallid sturgeon has increased almost exponentially in the 

last two decades (fig. 7). The challenge for science now is to 

transition from understanding what is possible (for example, 

Can pallid sturgeon spawn in the Missouri River? Does 

spawning habitat exist?) to what is probable and quantifiable 

(for example, Are pallid sturgeon spawning in sufficient numbers for population growth? How much habitat restoration is 

needed to meaningfully increase the number of wild-produced 

fish?). Progress in developing the science needed to inform 

management actions on the Missouri River will benefit from 

continuation of long-term monitoring of reproductive cycles, 

reproductive movements, growth, and survival of telemetry 

tagged adults. With new understanding, studies will increase 

emphasis on focused, complementary field and laboratory 

studies of factors influencing early life history, implementation of studies to resolve the role of food limitations in growth, 

survival, and reproductive condition, and design of studies so 

results can be used to parameterize models to assess effects of 

management actions.

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126 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Appendix 1. Reproductive Movements and Spawning, Lower Missouri River,

2012

broodstock in the pallid sturgeon hatchery population augmentation program also were implanted with transmitters before 

release back into the Missouri River near the site of capture. 

The annual goal of this study is to retain more than 80 adult 

sturgeon with active transmitters and known reproductive 

histories for long-term (5–10 years) analyses of migration 

patterns, spawning site selection and fidelity, and reproductive 

frequency and success.

Telemetered pallid sturgeon were located and tracked 

by USGS and NGPC field crews to record habitat use and 

seasonal movements. During pre- and post-spawn periods, 

segments of the Lower Missouri River were searched in an 

attempt to locate tagged sturgeon approximately one to three 

times per month (extensive tracking). During the spawning 

period, tracking strategies focused on the frequent location 

of individual tagged sturgeon rather than searching segments 

of the Missouri River (intensive tracking). Pallid sturgeon 

in reproductive condition were located weekly to daily 

from March through June when water temperatures reached 

14–16 degrees Celsius (°C) until spawning behavior was 

observed or reproductive assessments indicated that spawning was unsuccessful. Spawning behavior of female pallid 

sturgeon is recognized as a repeated series of movements up 

and down along a 0.5–0.8-kilometer (km) length of a revetted outside bend or over other coarse substrate (DeLonay 

and others, 2009). Repeated series of movements cease after 

12–36 hours, and the female remains stationary for some 

period of time before leaving the spawning area, typically 

moving downstream. Spawning in each case was verified 

through recapture and reassessment of female reproductive 

status using minimally invasive ultrasonography with surgical verification. Telemetry crews attempted to collect daily to 

hourly observations of fish locations and habitat use during 

upstream migration and spawning. Telemetry tracking of pallid sturgeon in reproductive condition was prioritized to better 

allocate resources and increase the probability of documenting 

spawning events. Selected individuals were located several 

times daily during intensive tracking to monitor direction and 

rate of movement. Migrating females that were stationary for 

more than 6 hours were targeted for continuous monitoring 

and habitat characterization. Measurements of water quality 

(temperature, conductivity, dissolved oxygen, and turbidity) 

and habitat characteristics (depth and substrate) were recorded 

at each telemetry location. Spawning sites of telemetered pallid sturgeon were assessed using a combination of sampling 

for eggs or free embryos, capturing adult pallid sturgeon in 

reproductive condition, and identifying and documenting 

spawning behavior using dual-frequency identification sonar 

(DIDSON®) or side-scan sonar. Not all assessment methods 

were employed at each spawning location. Methods used at 

each location were determined by resource availability, river 

conditions, and safety considerations.

Background

During 2012, the Comprehensive Sturgeon Research 

Project (CSRP) had 67 tagged pallid sturgeon (Scaphirhynchus 

albus) under surveillance. Members of this population were 

located at various times during the year, and fish becoming 

reproductive or fish with expiring tag batteries were selected 

for recapture and retagging. Those fish that were determined to 

be reproductive were used for intensive tracking during migration and spawning to address the following questions:

•	 Where and under what conditions do pallid sturgeon 

spawn in the Lower Missouri River?

•	 Are there hydraulic impediments to migration to 

spawning sites?

•	 Are migrations or spawning behavior associated with 

specific environmental cues?

Information developed during 2012 also addressed 

emerging evidence of strong overwintering and spawning site 

fidelity for some fish and the potential for some fish to use 

tributaries for spawning, particularly the Platte River.

Scope and Objectives

This study addresses movements of reproductive, adult 

pallid sturgeon downstream of Gavins Point Dam on the 

Lower Missouri River. The objectives are to elucidate environmental conditions and cues associated with spawning, identify 

and characterize spawning sites, attempt to validate successful 

spawning with collection of free embryos, and continue to add 

information on geographic range of the pallid sturgeon.

Methods

Methods used in 2012 closely follow those developed and 

used by the CSRP during previous years (DeLonay and others, 

2007; DeLonay and others, 2009; DeLonay and others, 2010; 

DeLonay and others, 2012). In 2012, the U.S. Geological 

Survey (USGS) and the Nebraska Game and Parks Commission (NGPC) implanted and tracked female and male pallid 

sturgeon larger than 2 kilograms (kg) with 2-year acoustic 

transmitters and data storage tags (DSTs) recording depth and 

temperature at 30-minute intervals. At least one, but no more 

than four gravid females were targeted for device implantation 

within each of the two Lower Missouri River study sections 

(fig. 1–1). At least one, but no more than three, ripe males 

also were targeted for device implantation within each study 

section. Throughout the study, concerted efforts were made 

to recapture, reevaluate, and reimplant telemetered pallid 

sturgeon. Pallid sturgeon collected by other agencies for use as 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 127

Results

During the fall of 2011, the USGS and NGPC began 

recapturing and reimplanting telemetered pallid sturgeon in 

anticipation of 2012 studies. Using the Sturgeon Information Management System (SIMS), individual pallid sturgeon 

of both sexes were identified for recapture and reassessment 

based upon sex, reproductive history, movement within the 

past six months, and transmitter life expectancy. Sturgeon 

targeted by CSRP researchers were located and recaptured 

using drifted trammel nets as described in DeLonay and others 

(2009) from September through November 2011 and from 

February through November 2012. Trotline and gill net sampling for new, untagged reproductive adults began in February and continued through mid-March 2012. Temperatures 

in spring 2012 were exceptionally warm and few new adults 

were collected because field crews were shifted to intensively 

track reproductively ready female pallid sturgeon.

During 2012, 48 pallid sturgeon were captured, assessed, 

implanted with telemetry and DST devices, and released back 

into the Lower Missouri River. Of those, 46 were telemetry 

tagged pallid sturgeon that were recaptured and either reimplanted with a new acoustic tag or received a reproductive 

assessment. Spring 2012 sampling efforts yielded only one 

additional female pallid sturgeon in nonreproductive condition 

to the CSRP. An additional female in nonreproductive condition was transferred to the CSRP from the population augmentation program and tagged before return to the river. Four 

female pallid sturgeon (PLS11-007, PLS11-019, PLS09-011, 

and PLS10-023) captured during the fall of 2011 and spring 

of 2012 using targeted recapture methods were examined and 

determined to be likely to spawn in the spring of 2012. One of 

the reproductive females (PLS11-007) was recaptured in the 

lower Missouri River study section, whereas the other three 

females were recaptured in the upper Missouri River study 

section. The four females were intensively tracked during the 

Map area

Mississi ppi River

Illinois

River

Osage River

Kansas River

Grand Riv er

Missouri Rive

P

r

latte River

0

600

700

500

800

300 400

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!

River mile marker—Number 

is distance upstream from 

the confluence with the 

Mississippi River, in miles 

Lower Missouri River study section

Upper Missouri River study section

100° 96°

42°

40°

38°

36°

Base from U.S. Geological digital data, 1999, 1:100,000

Gavins Point National Fish Hatchery

Blind Pony State 

Fish Hatchery

Neosho National Fish Hatchery

0

0 50 100 KILOMETERS

50 100 MILES

EXPLANATION

GAVINS

POINT

DAM

FORT RANDALL DAM

600

92°

KANSAS

MISSOURI

IOWA

NEBRASKA

ILLINOIS

SOUTH DAKOTA

ARKANSAS

OKLAHOMA

Figure 1–1. Comprehensive Sturgeon Research Project study sections and pallid sturgeon hatchery locations within the Lower 

Missouri River Basin.
128 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

spring of 2012 to document spawning location and success. 

Two of the four females were tracked to their likely spawning 

locations, subsequently recaptured, and determined to have 

spawned. Free-embryo sampling was executed at these two 

locations, one in the lower Missouri River study section and 

one in the upper Missouri River study section. One intensively 

tracked female (PLS11-019) in the upper Missouri River study 

section exhibited a complex movement pattern, which made 

determining the exact spawning location difficult. Another 

intensively tracked female (PLS10-023) failed to begin 

upstream migration and ultimately failed to spawn. Examination of her ovaries upon recapture showed that she had not 

released her eggs and was in an advanced stage of atresia. 

One additional female pallid sturgeon (PLS10-029) was not 

reproductively assessed before the spawning season but was 

extensively tracked during the spring of 2012. Late recapture 

of PLS10-029 indicated that it had been in reproductive condition in 2012 and likely spawned in the Platte River.

Female pallid sturgeon PLS11-007 was captured in 

nonreproductive condition on April 5, 2011, in the lower Missouri River study section. Female pallid sturgeon PLS11-007 

was implanted with a telemetry transmitter and DST device 

and released back into the Missouri River near river mile 

(RM) 200. This female was located near (within 0.5 mile 

[mi]) her initial capture location on 13 occasions throughout 

the remainder of spring and summer 2011. Evaluations of 

reproductive readiness on September 16, 2011, and again on 

March 15, 2012, indicated that PLS11-007 would be ready to 

spawn during spring 2012. From September through December 2011, PLS11-007 moved upstream approximately 100 mi 

and resumed her migration into the spring, travelling 20 mi 

upstream in March of 2012. PLS11-007 was hypothesized to 

have spawned on an outside bend near RM 322 from March 

30 through 31 (fig. 1–2). Water temperature during this time 

ranged from 19.3 to 20 °C. This spawning event was approximately 4–6 weeks earlier than previous spawning events 

documented from 2007 through 2011. DIDSON® imagery 

of PLS11-007 at the spawning site on March 31 was suggestive of spawning behavior. The female was present with 

other large sturgeon and moving short distances upstream 

and downstream along the base of the revetted outside bend. 

The repeated movement series ended abruptly, and the 

female moved into the navigation channel and began moving 

downstream. DIDSON® imagery showed that she was alone. 

Female PLS11-007 was recaptured on April 3, 2012, and 

found to have spawned completely. Field crews sampled for 

free embryos during the time that eggs were likely to hatch 

based on calculated developmental times at ambient river 

temperatures. The expectation was that free embryos would 

disperse immediately upon hatching. Free-embryo sampling 

from April 3 through 6, 2012, resulted in the collection of one 

early stage Scaphirhynchus spp. free embryo immediately 

downstream from the probable spawning site of PLS11-007. 

Subsequent genetic analyses confirmed that the collected free 

embryo was a shovelnose sturgeon (Scaphirhynchus platorynchus) (Heist and Eichelberger, 2013).

Female pallid sturgeon PLS11-019 was captured near 

RM 717 in the upper Missouri River study section and 

transported to the Neosho National Fish Hatchery (fig. 1–1) 

on March 30, 2010. This female was retained in the conservation augmentation program for more than 1 year before 

being released to the CSRP on May 4, 2011, in nonreproductive condition. She was implanted with a telemetry transmitter and DST device and released near the initial capture 

site. PLS11-019 moved approximately 50 RM downstream 

by October 13, 2011. During late October and November 

2011 she moved back upstream approximately 25 mi near 

RM 700. PLS11-019 was recaptured near this location on 

March 15, 2012 (fig. 1–3). A reproductive evaluation performed at that time indicated female PLS11-019 would be 

ready to spawn during spring 2012. Intensive tracking of this 

female pallid sturgeon began on April 2, 2012. The migration pattern of PLS11-019 was recorded as an irregular series 

of upstream and downstream movements, making the exact 

spawning behavior and location difficult to discern. PLS11-

019 was recaptured on May 31, 2012, and found to have 

spawned completely. PLS11-019 was hypothesized to have 

spawned between RM 700.1 and 713.7 between May 5 and 

May 31, 2012.

Female pallid sturgeon PLS09-011 was initially captured in nonreproductive condition near RM 563 on September 11, 2009. Evaluations of reproductive readiness on 

November 1, 2011, and again on March 23, 2012, indicated 

that this female would be ready to spawn during the spring of 

2012 (fig. 1–4). Intensive tracking of PLS09-011 was initiated on March 31, 2012. PLS09-011 moved consistently 

upstream until April 2, when she began moving downstream 

suggesting that she may have spawned; however, this downstream movement may have been related instead to a sudden 

drop in river temperatures. PLS09-011 was recaptured on 

April 10, 2012, and at that time had not yet spawned. This 

female then resumed upstream movements, reaching an apex 

near RM 636 on April 18; however, PLS09-011 did not exhibit 

a movement pattern indicative of spawning behavior. By April 

24, PLS09-011 had moved more than 50 mi downstream, 

initiating what appeared to be spawning behavior on April 26. 

Based on these movement patterns, PLS09-011 was hypothesized to have spawned between RM 579.8 and 580.6 from 

April 26 to 27, 2012. Water temperatures in the Missouri River 

during this time ranged from 16.1 to 17.4 °C. PLS09-011 was 

recaptured on April 27, 2012, and found to have spawned 

completely. The suspected spawning location was sampled 

for free embryos from May 1 through 4, 2012. Six early stage 

Scaphirhynchus spp. free embryos were collected immediately 

downstream from the probable spawning site of PLS09-011. 

The free embryos were estimated at less than 1 day post hatch. 

Subsequent genetic analyses confirmed that none of the free 

embryos were pallid sturgeon (Heist and Eichelberger, 2013).

Female pallid sturgeon PLS10-023 had been intensively 

tracked as a reproductive female in 2010. She was captured 

near RM 552.4 in the upper section of the Lower Missouri 

River and transported to the Blind Pony State Fish Hatchery 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 129

Date

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3/5/12 3/19/12 4/2/12 4/16/12 4/30/12 5/14/12 5/28/12

Lamine River

Movement range

Probable spawning location

Recapture

Missouri River telemetry location

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

320

EXPLANATION

210

"

"

320

310

300

290

260

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240

280

270

230

220

200

94° 93°30’ 93°

39°15’

39°

38°45'

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

Glasgow

Boonville

MISSOURI

0 105 KILOMETERS

0 5 10 MILES

Fish depth from archival tag

Water temperature from archival tag

Missouri River temperature

Missouri River discharge

Recapture

Missouri River 

telemetry 

location

EXPLANATION

A

B

Figure 1–2. Telemetry and archival tag data of female pallid sturgeon PLS11-

007. A, Movement range, probable spawning location, recapture locations, and 

Missouri River telemetry locations; and, B, fish depth and water temperature 

from archival tag, and Missouri River temperature and discharge from the 

streamgage at Glasgow, Missouri.
130 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

0

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Missouri River location, in river miles

Temperature, in degrees Celsius

Fish depth, in meters

Discharge, in one thousand cubic feet per second

3/5/12 3/19/12 4/2/12 4/16/12 4/30/12 5/14/12 5/28/12

42°

Fish depth from archival tag

Water temperature from archival tag

Missouri River temperature

Missouri River discharge

Recapture

Missouri River 

telemetry 

location

EXPLANATION

"

670

690

680

700

710

NEBRASKA

42°15’

96°40’ 96°15’ 95°50’

42°

IOWA

Little Sioux

River

Decatur

0 5 10 KILOMETERS

0 5 10 MILES

41°45’

Movement range

Probable spawning location

Recapture

Missouri River telemetry location

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

690

EXPLANATION

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

A

B

Figure 1–3. Telemetry and archival tag data of female pallid sturgeon 

PLS11-019. A, Movement range, probable spawning locations, recapture 

locations, and Missouri River telemetry locations; and, B, fish depth and 

water temperature from archival tag, and Missouri River temperature and 

discharge from the streamgage at Decatur, Nebraska.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 131

0

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Missouri River location, in river miles

Temperature, in degrees Celsius

Fish depth, in meters

Discharge, in one thousand cubic feet per second

Date

3/5/12 3/19/12 4/2/12 4/16/12 4/30/12 5/14/12 5/28/12

Fish depth from archival tag

Water temperature from archival tag

Missouri River temperature

Missouri River discharge

Recapture

Missouri River 

telemetry 

location

EXPLANATION

(

.

"

96°30’ 96° 95°30’

Omaha

IOWA

NEBRASKA

41°

41°15’

40°45’

Elkhorn River

Platte River

Movement range

Probable spawning location

Recapture

Missouri River telemetry location

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

570

EXPLANATION

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

0 5 10 KILOMETERS

0 5 10 MILES

590

580

600

560

610

570

620

630

640

A

B

Figure 1–4. Telemetry and archival tag data of female pallid sturgeon 

PLS09-011. A, Movement range, probable spawning location, recapture 

locations, and Missouri River telemetry locations; and, B, fish depth and 

water temperature from archival tag, and Missouri River temperature and 

discharge from the streamgage at Omaha, Nebraska.
132 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

not evaluated prior to the spring 2012, nor was this female 

intensively tracked during that time, but was recaptured in 

post-spawn condition with few remaining oocytes on May 

2, 2012. Temperature data downloaded from the implanted 

DST device closely matched the temperature profile of the 

Platte River for much of March and April 2012 (fig. 1–6). 

Based on the comparison of temperature profiles, PLS10-

029 was hypothesized to have spawned in the Platte River. 

Although the exact spawning location was not observed, this 

data supports the hypothesis that pallid sturgeon are spawning 

somewhere in the Platte River or its tributaries (DeLonay and 

others, 2014).

Summary

Intensive and extensive tracking efforts since 2007 have 

resulted in the documentation of 18 spawning events of female 

pallid sturgeon in the Lower Missouri River and 4 spawning 

events in the Platte River. The precision of documentation varies for spawning events. Descriptions of spawning events for 

some intensively tracked and recaptured females have defined 

spawning as depositing eggs over a few hundred meters of an 

outside bend of the river in a 24–36-hour period (DeLonay 

and others, 2009) after a characteristic upstream migration. Estimates of the spawning location and timing of other 

telemetered females were broadly defined, especially if the 

migration pattern of intensively tracked females was complex 

and disrupted without clear observation of spawning behavior, 

or if the females were tracked only extensively and had only 

a few observations between the initial reproductive evaluation and the post-spawn recapture (DeLonay and others, 2009; 

DeLonay and others, 2012). Individual pallid sturgeon of both 

sexes have been documented returning to the same section 

of river to spawn (DeLonay and others, 2010; DeLonay and 

others, 2012). Long-term (5–10 years) tracking of individual 

pallid sturgeon will be required to assess the level of spawning 

site fidelity and the role this geographic specificity may play in 

preserving the population genetic structure.

(fig. 1–1) on April 14, 2010. The female did not meet genetic 

criteria for use as propagation broodstock and was released 

back into the river with an implanted transmitter. Conservative 

species probability assignment thresholds used in the conservation augmentation program could not sufficiently rule out 

the possibility of hybridization with shovelnose sturgeon one 

or more generations removed from this individual’s parents 

(Heist and others, Southern Illinois University Carbondale, 

Carbondale, Illinois, written commun., 2010; DeLonay and 

others, 2012). This female subsequently spawned in 2010, 

though the exact location was not documented (DeLonay 

and others, 2012). This female was targeted for recapture and 

transmitter reimplantation on April 13, 2012 (fig. 1–5). Field 

assessments of reproductive condition at the time indicated 

that this female was reproductively ready and would likely 

spawn during spring 2012. Female PLS10-023 did not initiate 

upstream migration, displaying minor upstream and downstream movements between RM 592 and 583 from April 15 to 

May 3, 2012. Between May 3 and May 6, PLS10-023 moved 

downstream approximately 18 RM, indicating that she may 

have spawned. PLS10-023 was recaptured on May 8, 2012, at 

RM 563.1. Reproductive assessments determined that PLS10-

023 had failed to spawn and was in advanced state of atresia.

Female pallid sturgeon PLS10-029 was captured near 

RM 563.2 in the Missouri River and transported to the Neosho National Fish Hatchery (fig. 1–1) on March 31, 2009. 

PLS10-029 spent more than 1 year in captivity before being 

used as broodstock for the population augmentation program 

in the spring of 2010. This female pallid sturgeon was then 

released to the CSRP on May 7, 2010, in post-spawn condition, implanted with a telemetry transmitter and DST device, 

and released near her initial capture site. The movements of 

PLS10-029 were recorded from approximately RM 700 to 

590 in the Missouri River during 2010 and 2011. On May 

11, 2011, PLS10-029 was located in the Platte River near the 

mouth of the Elkhorn River, approximately 33 RM upstream 

from the confluence of the Platte and Missouri Rivers. By 

October 2011, PLS10-029 was located near RM 590 in the 

Missouri River. The reproductive condition of PLS10-029 was 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 133

Figure 1–5. Telemetry and archival tag data of female pallid sturgeon 

PLS10-023. A, Movement range, recapture locations, and Missouri River 

telemetry locations; and, B, fish depth and water temperature from 

archival tag, and Missouri River temperature and discharge from the 

streamgage at Omaha, Nebraska.

0

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Missouri River location, in river miles

Temperature, in degrees Celsius

Fish depth, in meters

Discharge, in one thousand cubic feet per second

Fish depth from archival tag

Water temperature from archival tag

Missouri River temperature

Missouri River discharge

Recapture

Missouri River 

telemetry 

location

EXPLANATION Date

3/5/12 3/19/12 4/2/12 4/16/12 4/30/12 5/14/12 5/28/12

(

(

(

.

590

580

570

560

550

540

530

520

510

500

490

NEBRASKA

Nebraska City

96° 95°15’

MISSOURI

IOWA

40°30’

40°

41°

Movement range

Recapture

Missouri River telemetry location

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

500

EXPLANATION

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

Little Nemaha River

Big Nemaha River

0 10 KILOMETERS 5

0 5 10 MILES

A

B
134 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

-10

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Missouri River location, in river miles

Temperature, in degrees Celsius

Fish depth, in meters

Discharge, in one thousand cubic feet per second

Fish depth from archival tag

Water temperature from archival tag

Platte River temperature

Recapture

Missouri River 

telemetry 

Missouri River temperature location

Missouri River discharge

EXPLANATION Date

3/5/12 3/19/12 4/2/12 4/16/12 4/30/12 5/14/12 5/28/12

"

590

600

560

610

570

580

620

0 5 10 KILOMETERS

0 5 10 MILES

Olive Branch

Elkhorn River

Platte River

96°30’ 96°15’ 96° 95°45’ 95°30’

41°

41°15’

40°45’

Movement range

Recapture

Missouri River telemetry location

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

570

EXPLANATION

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

Omaha

NEBRASKA IOWA

A

B

Figure 1–6. Telemetry and archival tag data of female pallid sturgeon 

PLS10-029. A, Movement range, recapture location, and Missouri 

River telemetry locations; and, B, fish depth and water temperature 

from archival tag, Platte River temperature from the streamgage at 

Louisville, Nebraska, and Missouri River temperature and discharge 

from the streamgage at Omaha, Nebraska.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 135

References Cited

DeLonay, A.J., Everitt, D.W., Papoulias, D.M., Wildhaber, 

M.L., Mestl, G.E., and Chojnacki, K.A., 2007, Movement, habitat use, and reproductive behavior of shovelnose 

sturgeon and pallid sturgeon in the lower Missouri River, 

in Korschgen, C.E., ed., Factors affecting the reproduction, recruitment, habitat, and population dynamics of 

pallid sturgeon and shovelnose sturgeon in the Missouri 

River: U.S. Geological Survey Open-File Report 2007–

1262, p. 23–102. [Also available at http://pubs.usgs.gov/

of/2007/1262/pdf/OF2007-1262.pdf.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Simpkins, 

D.G., Wildhaber, M.L., Reuter, J.M., Bonnot, T.W., Chojnacki, K.A., Korschgen, C.E., Mestl, G.E., and Mac, M.J., 

2009, Ecological requirements of pallid sturgeon reproduction and recruitment in the lower Missouri River—A 

research synthesis 2005–08: U.S. Geological Survey OpenFile Report 2009–5201, 59 p. [Also available at http://pubs.

usgs.gov/sir/2009/5201/.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Wildhaber, 

M.L., Chojnacki, K.A., Pherigo, E.K., Bergthold, C.L., 

and Mestl, G.E., 2010, Ecological requirements of pallid 

sturgeon reproduction and recruitment in the lower Missouri 

River—Annual report 2009: U.S. Geological Survey OpenFile Report 2010–1215, 64 p. [Also available at http://pubs.

usgs.gov/of/2010/1215/.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Wildhaber, M.L., Chojnacki, K.A., Pherigo, E.K., Haas, J.D., 

and Mestl, G.E., 2012, Ecological requirements for pallid 

sturgeon reproduction and recruitment in the lower Missouri 

River—Annual report 2010: U.S. Geological Survey OpenFile Report 2012–1009, 51 p. [Also available at http://pubs.

usgs.gov/of/2012/1009/.]

DeLonay, A.J., Jacobson, R.B., Annis, M.L., Braaten, P.J., 

Chojnacki, K.A., Elliott, C.M., Fuller, D.B., Haas, J.D., 

Haddix, T.M., McElroy, B.J., Mestl, G.E., Papoulias, D.M., 

Rhoten, J.C., and Wildhaber, M.L., 2014, Ecological 

requirements for pallid sturgeon reproduction and recruitment in the Missouri River—Annual report 2011: U.S. Geological Survey Open-File Report 2014–1106, 96 p. [Also 

available at http://dx.doi.org/10.3133/ofr20141106.]

Heist, E.J., and Eichelberger, J., 2013, 2012 genetic analysis of 

Missouri River sturgeon larvae: Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University 

Carbondale, 27 p.
136 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Appendix 2. Examination of Pallid Sturgeon Use, Migrations, and Spawning in 

the Milk River and Missouri River downstream from Fort Peck Dam during 2012

Additional information is being collected to determine 

the flow regimes needed to trigger migrations and spawning 

of pallid sturgeon in the Missouri River below Fort Peck Dam. 

This study focused on evaluating use, migrations, and spawning of pallid sturgeon in the Milk River and Missouri River 

downstream from Fort Peck Dam.

Scope and Objectives

The objectives of this work were (1) to assess pallid 

sturgeon migrations and use of the Milk River and Missouri 

River between Fort Peck Dam and the Yellowstone River 

confluence; (2) to quantify reproductive products (eggs, free 

embryos, larvae) and potential spawning reaches in the Milk 

River and Missouri River below Fort Peck Dam; and (3) to 

assess and quantify settlement of pallid sturgeon larvae from 

the drift based on collections of young-of-year pallid sturgeon 

in lower reaches of the Missouri River.

Study Area

The Missouri River study area extended from Fort 

Peck Dam located at river mile (RM) 1,770 downstream to 

RM 1,553.5 (near Williston, North Dakota; fig. 2–1). The 

study area also included the lower 115 miles of the Milk River 

from Vandalia Dam to its confluence with the Missouri River.

Background

The Lower Yellowstone River and Missouri River 

between Fort Peck Dam and Lake Sakakawea is inhabited by 

a wild adult population of federally endangered pallid sturgeon (Scaphirhynchus albus). During the last 2 decades, pallid 

sturgeon in this section of the Upper Missouri River Basin 

have been the focus of several studies examining movements, 

migrations, and habitat use (Bramblett and White, 2001; Fuller 

and others, 2008; Fuller and Braaten, 2012).

In 2011, record setting snowfall coupled with record 

spring rains resulted in rapid filling of Fort Peck Reservoir 

above full pool, and subsequently releasing water over the Fort 

Peck Spillway. The hydrologic regime in the Missouri River 

downstream of Fort Peck Dam during 2011 was unique among 

the last several years because of these spillway releases, 

increased discharge from the Fort Peck powerhouses, and 

elevated discharge conditions during spring and early summer 

from the Milk River. This resulted in an increased use by adult 

pallid sturgeon (DeLonay and others, 2014) and hatcheryreared juvenile pallid sturgeon (Hunziker and others, 2013) in 

the reach of the Missouri River from Fort Peck Dam to Wolf 

Point. Additionally, an aggregation of adult pallid sturgeon 

was located just downstream of the Milk River, and the first 

genetically confirmed, naturally spawned pallid sturgeon free 

embryo was collected in this reach (DeLonay and others, 

2014).

106°00’ 104°00’

Base from U.S. Geological Survey digital data, 2012, 1:100,000

Universal Transverse Mercator projection, zone 13

FORT PECK LAKE

Milk River

LAKE

SAKAKAWEA

Upper Missouri River study section

MONTANA

NORTH DAKOTA

Williston Culbertson

Nohly

Wolf

Grand Point

Champs

Sidney

Mile 0.5

Glendive

INTAKE DAM

Powder River

Redwater River

Poplar River

Mile 2.5

FORT PECK DAM

VANDALIA

DAM

0 30 60 KILOMETERS 15

0 30

45

15 45 60 MILES

48°00’

47°30’

47°00’

48°30’

River mile marker

EXPLANATION

Yellowstone River study section

Figure 2–1. Location of Upper 

Missouri River and Yellowstone 

River study sections.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 137

Methods

Pallid sturgeon were captured using drifted trammel nets 

and were implanted with radio tags (MCFT-3L tags, 16 millimeters [mm]x73 mm, air weight=26 grams [g], 2,929-day 

longevity, 5-second pulse interval, 149.760 megahertz [MHz], 

Lotek Wireless Incorporated, New Market, Ontario). The 

coded signal emitted by each tag is unique to facilitate identification of individual fish. Most fish were collected and tagged 

during broodstock collections in previous years near the confluence of the Missouri and Yellowstone Rivers.

Manual tracking of fish during 2012 was initiated in 

April. The Missouri River between Fort Peck Dam and Wolf 

Point (70 kilometers [km]) was tracked from April through 

October. The Milk River was not manually tracked in 2012 

(see, “Results”). One radio frequency (149.760 MHz) was 

monitored during the boat-tracking run using a 4-element Yagi 

antenna. Fish code, latitude, longitude, and time of day were 

recorded at fish locations.

Stationary telemetry logging stations were deployed in 

April 2012 at four sites on the Missouri River (Nickels, RM 

1,760; near Wolf Point, RM 1,720; near Culbertson, RM 

1,620; at RM 1,584 just upstream from the Yellowstone River 

confluence), one site on the Milk River (RM 2.5), and several 

sites on the Yellowstone River, which are mentioned in a separate section of this report (“Appendix 4”). The logging stations 

were placed on shore with two 4-element Yagi antennae 

facing upstream and downstream. Each logging station was 

equipped with a battery powered receiver (Lotek SRX-400), 

solar panel, an environmental enclosure kit containing dual 

12-volt batteries, and an antenna switchbox. Data recorded by 

the logging stations were downloaded to a laptop computer 

two times per month between April and October. Coupled with 

manual tracking efforts, the array of telemetry logging stations 

facilitated detection of dates and times of movement events 

between and within rivers and river reaches.

Free embryos and larvae were sampled in the lower 

Milk River and Missouri River near Wolf Point following 

methods outlined in Braaten and others (2010). Sampling 

was done two times per week at multiple replicate locations. 

After sampling was completed, net contents were transferred 

to black rubber trays where Acipenseriformes free embryos 

and larvae (sturgeon and paddlefish) were extracted from the 

detritus. Extracted Acipenseriformes were placed immediately 

in 95-percent nondenatured ethanol for genetic analysis. After 

extracting the specimens, the remaining sample was placed in 

a 10-percent formalin solution containing phloxine-B dye, and 

contents were separated and identified in the lab.

Targeted sampling for young-of-year pallid sturgeon followed trawling methods outlined in Braaten and Fuller (2007) 

and was conducted every week from mid-July through midSeptember. Sampling for young-of-year sturgeon (Scaphirhynchus spp.) was conducted with a benthic beam trawl 

in the Missouri River above the confluence (ATC) with the 

Yellowstone River and Missouri River below the confluence 

(BTC) with the Yellowstone River. Four replicate-sampling 

locations were established at each site where each replicate 

consisted of an inside bend, outside bend, and channel crossover habitat complex associated with a river bend. Fin clips 

were obtained for all Scaphirhynchus spp. collected, stored 

in 95-percent ethanol, and genetically processed by Southern 

Illinois University to distinguish individuals as pallid sturgeon or shovelnose sturgeon (Scaphirhynchus platorynchus). 

If identified as a pallid sturgeon, further analysis was done to 

determine parentage.

Results

Telemetered wild adult pallid sturgeon (n=41) were manually tracked in the Missouri River ATC to Fort Peck Dam. 

There was no use of the Milk River by telemetered pallid 

sturgeon in 2012. Similar to 2005–2010, use of the Missouri 

River ATC by adult pallid sturgeon in 2012 declined through 

the spring and reached a low during the spawning season (less 

than [<] 10 percent from late May to July; fig. 2–2). Only two 

fish were located upstream of Wolf Point in 2012 prior to the 

spawning season; however, both emigrated out of this reach 

and into the Yellowstone River by late May. Use of this reach 

increased in July as fish completed spawning in the Yellowstone River and migrated to post-spawn areas in the Missouri 

River ATC and BTC with the Yellowstone River where most 

would eventually winter.

Free embryos and larvae were sampled in the Milk River 

during 16 events spanning from May 22 through July 17, 

2012. No sturgeon or paddlefish larvae were collected during 

this time. Free embryo and larval sampling was done on the 

Missouri River near Wolf Point during 20 events from May 

23 through July 26, 2012. A total of 109 paddlefish and 31 

Scaphirhynchus sturgeon was collected (table 2–1). Genetic 

analysis of the Scaphirhynchus sturgeon indicated that they 

were all shovelnose sturgeon.

Beam trawling for young-of-year sturgeon was done 

weekly from July 24 through September 11, 2012. Channel 

catfish (Ictalurus punctatus) and sturgeon chub (Macrhybopsis gelida) made up 65 percent and 19 percent of the catch, 

respectively (table 2–2). A total of 156 young-of-year sturgeon 

was collected in the Missouri River ATC, whereas one was 

collected in the Missouri River BTC. All were determined to 

be shovelnose sturgeon through genetic analysis (Heist and 

Eichelberger, 2013).

Based on the small size of these shovelnose sturgeon 

collected in September (34–152 mm) spawning was prolonged 

in 2012 (table 2–3). This was most likely because of sustained 

high discharge (approximately 12,000 cubic feet per second 

[ft3

/s]) from Fort Peck Dam and cool water temperatures 

associated with hypolimnetic releases from the dam. Although 

sampling ceased on July 26, it is likely shovelnose-sturgeon 

embryos were hatching into mid-August based on growth 

models developed by Braaten and Fuller (2007).
138 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Summary

During 2012, there was very little use by wild adult 

pallid sturgeon of the Missouri River above the confluence 

with the Yellowstone River, and no sturgeon were detected 

in the Milk River. These results are very similar to every 

other year in which no spillway releases were implemented 

or in which high flows did not originate from the Milk 

River.

Documentation of pallid sturgeon using, spawning, hatching, and dispersing free embryos in the Upper Missouri River 

downstream of Fort Peck Dam in 2011 indicates that the Missouri River can be used by pallid sturgeon when there are large 

flow pulses (DeLonay and others, 2014). Results of the 2011 

study added substantial new information on pallid sturgeon 

movement, river use, and behavior. Verification of successful 

reproduction by wild pallid sturgeon has provided information 

that shows spawning, fertilization, egg survival, and hatching is possible in the Missouri River when flows deviate from 

baseline operations.

In comparison, successful spawning of shovelnose 

sturgeon has been documented in the Missouri River downstream from Fort Peck Dam every year since 2001 (DeLonay 

and others, 2014; Fuller and Braaten, 2013). These spawning 

events may be from a population of shovelnose sturgeon that 

resides year-round in areas of the Missouri River upstream of 

Wolf Point; therefore, unlike pallid sturgeon, which typically 

reside lower in the Missouri River outside of the spawning 

season, flow-pulse migration cues may not be required to draw 

shovelnose sturgeon to upstream spawning reaches in the 

Upper Missouri River.

Further studies on conditions required to cue pallid 

sturgeon to migrate into the Missouri River and spawn would 

have value. The 2011 hydrologic conditions were extreme 

and may have had much higher flows than were necessary to 

cue migration. Since very few sexually mature adult pallid 

sturgeon have been observed in the Missouri River with the 

exception of 2011, limited data exist that details the minimum 

flow parameters required to stimulate wild pallid sturgeon 

migrations and spawning.

Date

Apr. May June July Aug. Sept. Oct. 

Telemetered pallid sturgeon in the Missouri River

above the Yellowstone River, in percent

0

10

20

30

40

2011 (n = 31)

2010 (n = 33)

2009 (n = 34)

2008 (n = 31)

2007 (n = 22)

2006 (n = 19)

2005 (n = 18)

2012 (n = 41)

EXPLANATION

Figure 2–2. Percent of telemetered adult pallid sturgeon located in the Missouri River above the confluence with 

the Yellowstone River, 2005–12.

Table 2–1. Sampling dates and paddlefish, shovelnose sturgeon, and pallid sturgeon free embryos and larvae collected in the Missouri 

River near Wolf Point, Montana, in 2012.

Date May June July Total

23 25 29 1 6 7 11 14 18 21 26 28 2 5 11 13 16 19 22 26

Paddlefish 0 0 0 0 0 0 0 13 13 1 7 2 7 29 21 12 3 0 1 0 109

Shovelnose sturgeon 0 0 0 0 0 0 0 0 0 0 0 0 0 4 2 2 11 3 7 2 31

Pallid sturgeon 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 139

Table 2–2. Total catch of fish by the benthic trawl in the Missouri River above the confluence 

of the Yellowstone River (MRATC), Missouri River below the confluence of the Yellowstone 

River (MRBTC), and total catch from July 24 to September 11, 2012.

[YOY, young-of-year; --, none collected]

Species (MRATC) (MRBTC) Total

Number of trawls without fish 26 10 36

Blue sucker (Cycleptus elongatus) -- 2 2

Channel catfish (Ictalurus punctatus) 26 1,635 1,661

Common carp (Cyprinus carpio) -- 3 3

Emerald shiner (Notropis atherinoides) 4 12 16

Flathead chub (Platygobio gracilis) 19 25 44

Freshwater drum (Aplodinotus grunniens) 1 23 24

Goldeye (Hiodon alosoides) -- 1 1

Longnose dace (Rhinichthys cataractae) -- 4 4

Paddlefish (Polyodon spathula) -- 1 1

Pallid sturgeon (Scaphirhynchus albus)1 3 7 10

River carpsucker (Carpiodes carpio) -- 5 5

Sauger (Sander canadensis) -- 25 25

Sicklefin chub (Macrhybopsis meeki) 19 18 37

Sturgeon chub (Macrhybopsis gelida) 92 396 488

Shovelnose sturgeon (Scaphirhynchus platorynchus) 4 17 21

Shovelnose sturgeon (YOY) 1 156 157

Stonecat (Noturus flavus) 1 55 56

Unidentified chub (Hybognathus spp.) -- 9 9

Unidentified Cyprinidae -- 1 1

Walleye (Sander vitreus) -- 3 3

White bass (Morone chrysops) -- 1 1

White crappie (Pomoxis annularis) -- 3 3

White sucker (Catostomus commersonii) -- 1 1

Total 170 2,403 2,573

1

Nonwild, hatchery-origin.

Table 2–3. Catch of shovelnose sturgeon in standard trawls and targeted trawls in the Missouri River during 2012 by date.

[n, number]

Date Total 

(n)

Standard 

(n)

Targeted 

(n)

Minimum length, 

in millimeters

Maximum length, 

in millimeters

Mean length, 

in millimeters

7/24/2012 5 1 4 18 45 29

7/30/2012 13 4 9 13 67 29.8

8/8/2012 37 8 29 20 112 38

8/14/2012 39 8 31 27 63 34.8

8/22/2012 7 5 2 33 76 53.1

8/28/2012 18 8 10 26 135 50.8

9/5/2012 12 5 7 34 152 71.6

9/11/2012 26 4 22 38 98 66.1
140 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

References Cited

Bramblett, R.G., and White, R.G., 2001, Habitat use and 

movements of pallid and shovelnose sturgeon in the 

Yellowstone and Missouri Rivers in Montana and North 

Dakota: Transactions of the American Fisheries Society, 

v. 130, no. 6, p. 1006–1025. [Also available at http://dx.doi.

org/10.1577/1548-8659(2001)130<1006:HUAMOP>2.0

.CO;2.]

Braaten, P.J., and Fuller, D.B., 2007, Growth rates of youngof-year shovelnose sturgeon in the upper Missouri River: 

Journal of Applied Ichthyology, v. 23, no. 4, p. 506–515. 

[Also available at http://dx.doi.org/10.1111/j.1439-

0426.2006.00821.x.]

Braaten, P.J., Fuller, D.B., Lott, R.D., Ruggles, M.P., and 

Holm, R.J., 2010, Spatial distribution of drifting pallid sturgeon larvae in the Missouri River inferred from 

two net designs and multiple sampling locations: North 

American Journal of Fisheries Management, v. 30, no. 4, 

p. 1062–1074. [Also available at http://dx.doi.org/10.1577/

M09-149.1.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Wildhaber, M.L., Chojnacki, K.A., Pherigo, E.K., Hass, J.D., 

and Mestl, G.E., 2014, Ecological requirements of pallid 

sturgeon reproduction and recruitment in the lower Missouri 

River—Annual report 2011: U.S. Geological Survey, 63 p. 

Fuller, D.B., and Braaten, P.J., 2012, Fort Peck flow modification biological collection plan compendium—A summary of 

2001–2009 activities: Report prepared for the U.S. Geological Survey and the U.S. Army Corps of Engineers, Omaha 

District, Montana Fish, Wildlife and Parks. 

Fuller, D.B., and Braaten, P.J., 2013, Fort Peck flow modification biological data collection plan—Summary of 2001–

2009 activities: Report submitted to the U.S. Army Corps of 

Engineers, Montana Fish, Wildlife and Parks. 

Fuller, D.B., Jaeger, M.E., and Webb, Molly, 2008, Spawning 

and associated movement patterns of pallid sturgeon in the 

lower Yellowstone River: Western Area Power Administration, Upper Basin Pallid Sturgeon Work Group, U.S. Army 

Corps of Engineers, Montana Fish, Wildlife and Parks, 22 p. 

Heist, E.J., and Eichelberger, J., 2013, 2012 genetic analysis of 

Missouri River sturgeon larvae: Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University 

Carbondale, 27 p.

Hunziker, J.R., Haddix, T.M., Holte, L.D., and Lott, R.D., 

2013, 2012 annual report—Pallid sturgeon population 

assessment and associated monitoring for the Missouri 

River—Segment 2: Fort Peck, Mont., Montana Fish, Wildlife and Parks, 30 p.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 141

Appendix 3. Mapping and Quantifying Spawning and Larval Habitats, Lower 

Missouri and Yellowstone Rivers, 2012

The third objective was to quantify habitats associated 

with catches of free-embryo sturgeon in the Lower Missouri 

River. Within this objective we attempted to understand how 

reach-scale hydraulics may affect transport and retention of 

larvae, and to quantify velocity fields associated with coordinated larval sampling efforts.

Methods

Habitat survey methods employed in 2012 replicated 

those used in 2008–2011; detailed documentation of methods 

are on file at the Columbia Environmental Research Center 

(CERC). For the spawning habitat objective, fish locations 

were selected based on their likelihood as spawning sites as 

documented by telemetric data. Hydroacoustic boats were 

deployed to fish locations for high-resolution multibeam 

bathymetry and acoustic Doppler current profiler (ADCP) 

surveys when discharges were within 10 percent of the discharge that existed when the fish was located. For the second 

objective of mapping migration habitats, hydroacoustic boats 

surveyed over fish locations as they followed the upstream 

movements of tagged fish. Some of these surveys took place 

in near real-time with the survey vessel following as closely 

as 15 minutes behind the fish. As with the spawning habitat 

surveys, all surveys were completed when discharge was 

within 10 percent of discharge that existed when the fish were 

located.

The Research Vessel (R/V) Brush is equipped with a 

dual-receiver global positioning system (GPS) and inertial motion-sensing system, a multibeam echosounder for 

detailed mapping of the riverbed, and an ADCP for mapping 

current-velocity fields. Base stations were used to obtain 

real-time kinematic (RTK) positioning with nominal positioning errors of plus or minus (+/-) 0.02 meter (m) horizontal 

and +/-0.1 m vertical. The multibeam system is a RESON 

SeaBat® 7125 (RESON, Inc., Slangerup, Denmark) operating at 455 kilohertz (kHz). The transducer and receiver arrays 

are mounted on the front of the survey vessel on a tilt-up 

mount. The multibeam system collects data from 512 beams 

at 0.25-degree (°) spacing and is capable of mapping depths 

of approximately 1–200 m. The geometry allows a 128° swath 

covering a width of approximately four times the water depth. 

Positioning and motion sensing data were acquired using an 

Applanix POS-MV Wavemaster® system receiving broadcast 

RTK corrections from the base station. This unit also provides 

corrections for vessel heading, pitch, roll, and heave that are 

used to calculate sounding locations in conjunction with the 

multibeam sonar.

The multibeam system and boat mount were calibrated 

with a “patch” test that corrects for internal geometry of the 

boat, transducer/receiver, and GPS receiver. Patch test results 

were used to update geometry files used by the data-acquisition 

Background

Habitat is the three-dimensional space that animals 

inhabit; habitat commonly includes time as the fourth dimension to address dynamic changes through time. Habitat is 

also an intermediary between restoration and management 

actions that alter flow regime and channel morphology, and 

biotic responses to those management actions (Jacobson and 

Berkley, 2011). As such, understanding habitat quality, quantity, use, availability, and selection is critical to management 

of pallid sturgeon (Scaphirhynchus albus) populations in the 

Missouri River.

Detailed habitat mapping by the Comprehensive Sturgeon 

Research Project (CSRP) around tagged-fish locations places 

the behavior of individuals within a larger spatial context that 

allows researchers to characterize habitat availability and 

selection and, thereby, understand how channel morphology 

and flow regime can be managed to maximize reproduction 

and survival (Reuter and others, 2008; DeLonay and others, 

2009; Jacobson and others, 2009; Reuter and others, 2009; 

Bonnot and others, 2011).

Scope and Objectives

Habitat assessments in 2012 were done in the Lower 

Missouri and Yellowstone Rivers to quantify habitats used by 

pallid sturgeon and habitats that were available but not used to 

understand habitat selection. Paired with studies of reproductive movements and physiology, patterns of habitat selection 

can indicate if specific habitats are limiting the reproduction 

and survival of pallid sturgeon. Definition and quantification 

of spawning habitat was complemented with assessments of 

habitats used by upstream migrating reproductive sturgeon and 

assessments of channel-marginal habitats hypothesized to be 

the settling habitat of drifting larval sturgeon.

The first objective was to survey spawning habitats to 

replicate assessments done in 2008–2011and to increase 

understanding of how fine-scale habitat characteristics may 

affect spawning success and recruitment (Reuter and others, 

2008; DeLonay and others, 2009; Elliott and others, 2009; 

Reuter and others, 2009). An enhanced, high-resolution 

habitat-mapping protocol was implemented as described 

below (and as used in previous years) around fish locations 

identified by telemetry crews. The second objective was to 

survey habitats associated with upstream-migrating reproductive pallid sturgeon. These surveys were designed to test the 

hypothesis that migrating fish take paths that minimize the 

energetic expenditure necessary to arrive at spawning sites. 

Understanding the migration paths, and the energetic costs 

involved in navigating them, may lead to channel re-engineering designs that increase fecundity and reproductive success 

of sturgeon.
142 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

software. In addition, sound-velocity profiles were collected to 

assess stratification of sound velocity with depth. HYPACK/

HYSWEEP® software (Hypack, Inc., Middletown, Connecticut) was used to acquire, compile, correct, and edit GPS 

and multibeam data. Hypack and RESON provide real-time 

quality-control displays that are monitored to ensure quality 

data are collected. Total propagated vertical errors have been 

estimated at 0.06–0.15 m (Huizinga and others, 2010).

For high-resolution surveys, longitudinal survey lines 

were laid out in Hypack at intervals to ensure at least 50-percent overlap in multibeam coverage. The lines were parallel to 

the flow of the river and centered over the chosen fish location. A helm display showed the boat pilot the boat position, 

and the quality and extent of incoming data. Multibeam files 

were edited in the office to remove erroneous data. These data 

were subsequently exported from the Hypack environment 

and imported into Fledermaus (Quality Positioning Services 

[QPS], Portsmouth, New Hampshire) where the data were 

gridded at the 1-m scale using the Combined Uncertainty and 

Bathymetry Estimator (CUBE) algorithm (Calder and Mayer, 

2003; Calder and Wells, 2007) for analysis and display. The 

final grids were imported into ArcMap (Esri, Redlands, California) for map production and analysis with sturgeon telemetry data and other data.

Current velocity fields were mapped using a 1200 kHz 

ADCP (Teledyne RD Instruments, Poway, Calif.). Acoustic 

Doppler current profiler data were logged simultaneously with 

GPS data on a laptop computer running WinRiver® (version 

10.06, Teledyne RD Instruments, Poway, Calif.). Magnetic 

variation was set for each reach mapped by using GeoMagix® 

software (Interpex, Ltd., Golden, Colorado). Mapping crews 

completed the “Method 3” compass-calibration procedure 

at each site by rotating the boat in a tight circle (RD Instruments, 2003). This procedure corrects for one-cycle compass 

errors and was repeated until the total error reading was less 

than 1°. Configuration settings for ADCP data have a vertical 

resolution of 0.25 m (1200 kHz) and a blanking distance of 

0.50 m below the transducer head. Data from the ADCP were 

collected using water mode 1 with six water pings and bottom 

mode 5 with one bottom ping.

For spawning habitat surveys (objective one), channel 

cross-section lines for the ADCP survey were laid out in a grid 

with 20-m spacing in the direction of water flow over an area 

that equally covered the multibeam survey, which is approximately twice the width of the river. For migration habitat 

surveys (objective two), channel cross-section lines were laid 

out orthogonally to the local flow direction through the points 

where the fish was located. The spacing of these lines was 

determined by the rate of movement of the fish upstream and 

the rate at which a single cross-section could be surveyed or 

the fish could be relocated.

Results

Mapping efforts in 2012 were executed to document Missouri and Yellowstone River habitats used by pallid sturgeon 

over a range of life stages. Reproductive adult habitat use was 

assessed during migration and spawning life stages, age-0 

habitat use was documented over a range of discharges, and 

nonreproductive adult habitat was mapped in selected reaches 

where persistent occupancy has been established through multiyear, telemetry monitoring.

Probable pallid sturgeon spawning was assessed in two 

locations, one for reproductive female PLS11-007 near Lexington, Missouri, near river mile (RM) 322, and another for 

reproductive female PLS09-011 downstream from the Platte 

River near RM 580 ( fig. 3–1, fig. 3–2, table 3–1). Migration 

habitat measurements were done on the Lower Missouri River 

in Nebraska and on the Yellowstone River and included four 

repeat reciprocal transects at each fish location (table 3–1) 

(McElroy and others, 2012; DeLonay and others, 2014). Measurements on the Yellowstone River included documentation 

of pallid sturgeon migration habitat over a reach approaching 

Intake Dam near RM 73 (fig. 3–3). Larval and free-embryo 

sampling habitats were mapped over a range of discharges in 

a patch centered on a sampling transect in the Lower Missouri 

River near RM 33.3. Mapping efforts included four reciprocal 

transects over the fish sampling location and a patch of transects with a spacing of 20 m extending 200 m upstream and 

downstream from the sampling transect (fig. 3–4). The bend 

was mapped once to assess velocity and depth trends over a 

larger scale (table 3–1).

Mapping was also done to quantify habitat use of age-0 

sturgeon in reaches identified by U.S. Fish and Wildlife Service trawling crews (table 3–1). Additional mapping of pallid 

sturgeon habitat on the Lower Missouri River focused on persistent, multi-year telemetry patterns demonstrating site affinity of PLS08-006, a male pallid sturgeon who has migrated in 

a fairly predictable pattern from 2008 to 2012 (fig. 3–5). An 

additional site was mapped near RM 200; this site has been 

persistently occupied by several pallid sturgeon during the 

course of 2011–2012.

Summary

Habitat mapping in support of pallid sturgeon research in 

2012 was done over a wide range of life stages. The results for 

habitat use and availability of probable pallid sturgeon spawning and migration life stages are analyzed in the main body of 

this report (see “Adult Life Stage—Habitat Requirements for 

Adult Reproductive Fish”). Assessments of larval and age-0 

sturgeon sampling habitats and additional analysis of reaches 

of pallid sturgeon site affinity are ongoing.
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98°58’10” 93°58’ 93°57’50” 93°57’40” 

39°08’30”39°08’40”

Digital imagery from U.S. Department of Agriculture National Agriculture Imagery Program digital data, 2010Universal Transverse Mercator projection, zone 15

00 30 60 METERS

150 300 FEET River miles from U.S. Arm

Sturgeon locations fr

Aaron J. 

EXPLANATION

Discharges on the dateApril 12–13, 2012, at U.Survey streamgage at Missouri, were 52,700 feet per second. Dischprobable spawning ev2012, was 62,500 cubic 

322.5

322

11.30.3

Depth, in meters Depth-averaged velocity, in meters per second

0 to 0.5>0.5 to 1.00>1.00 to 1.50

>1.50 to 2.00>2.00 to 2.50>2.50 to 3.00

Sturgeon location—Locations of reproductive female 

pallid sturgeon PLS11-007 on March 31, 2012

River mile marker—Number is distance upstream from 

the confluence with the Mississippi River, in miles

322

Figure 3–1. Depth and depth-averaged velocity for probable spawning site, and location of reproductive female pallid sturgeon PLS11-007 nea

mile 322.
144 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

95°49’20” 95°49’10” 95°49’ 95°48’50” 95°48’40”

40°53’

40°52’40”

40°52’30”

40°52’50”

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0

0 50 100 METERS

Digital imagery from U.S. Department of Agriculture 200 400 FEET

National Agriculture Imagery Program digital data, 2010

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960;

Sturgeon locations from U.S. Geological Survey,

DeLonay and others, 2012; Aaron J. DeLonay,

unpub. data, 2012

Discharges on the dates of survey, May 1–2, 2012, 

at U.S. Geological Survey streamgage at 

Nebraska City, Nebraska, were 39,700 and 

40,800 cubic feet per second. Discharge during 

the probable spawning event on April 26, 2012, 

was 38,000 cubic feet per second. 

EXPLANATION

8.3

1.28

Depth, in meters Depth-averaged velocity, in meters per second

0 to 0.5

>0.5 to 1.00

>1.00 to 1.50

>1.50 to 2.00

>2.00 to 2.50

>2.50 to 3.00

Sturgeon location—Locations of reproductive female 

pallid sturgeon PLS09-011 on April 26, 2012

River mile marker—Number is distance upstream from 

the confluence with the Mississippi River, in miles

580

580

Figure 3–2. Depth and depth-averaged velocity for probable spawning site, and location of reproductive female 

pallid sturgeon PLS09-011 near Missouri River mile 580.
Figure 3–3. Depth-averaged velocity and pallid sturgeon telemetry locations for code 52 near Yellowstone River mile 73. 9:45 PM 9:42 PM 9:39 PM9:36 PM 9:35 PM 9:27 PM 8:54 PM 9:03 PM 8:33 PM 8:13 PM 7:52 PM 7:33 PM

104°32’ 104°31’ 

47°17’

47°16’30”47°17’15”47°16’45”

00 250 500 METERS

Digital imagery from U.S. Department of Agriculture 1,000 2,000 FEETNational Agriculture Imagery Program digital data, 2009

River miles from Yellows

EXPLANATION

Pallid sturgeon code 52Yellowstone River mile marker—Number 

is distance upstream from the Missouri River confluence, in miles

Depth-averaged velocity, in meters per second

0.32 to 0.500.51 to 0.750.76 to 1.001.01 to 1.251.26 to 1.50

1.51 to 1.751.76 to 2.002.01 to 2.252.26 to 2.502.51 to 2.75

73

72

73

Discharge on the date of survey, June 11, 2012, at the U.S. Geological Survey streamgage nearSidney, Montana, was 29,500 cubic feet per second. Discharge during pallid sturgeon telemetry location on June 9, 2012, was 39,600 cubic feet per second.
146 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

38°43’40” 38°43’40”

EXPLANATION

90°32’ 90°31’50” 90°31’40” 90°32’ 90°31’50” 90°31’40”

38°43’50”

38°44’

38°43’50”

38°44’

A. Depth B. Velocity

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2010

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

10.4

0.9

Depth, in meters Velocity, in meters

per second

Depth-averaged velocity, in meters per second

0 to 0.5

>0.5 to 1.00

>1.00 to 1.50

>1.50 to 2.00

>2.00 to 2.50

>2.50 to 3.00

Sampling location and number—Samples were taken 

using ichthyoplankton sampling nets at mid-water 

column and on or near the bed at depths >1 meter 

and at the bed at depths <1 meter

River mile marker—Number is distance upstream from 

the confluence with the Mississippi River, in miles 

Discharges on the dates of survey May 10, 2012, at the

U.S. Geological Survey streamgage at St. Charles, 

Missouri, was 134,000 cubic feet per second.

2.5

0.16

0

0

150

30

300 FEET

60 METERS

Figure 3–4. Flow characteristics of free-embryo pallid sturgeon sampling locations near Missouri River mile 33.3. A, depth, and 

B, depth-averaged velocity.
Table 3–1. Sturgeon habitat mapping 2012 data collection effort on the Missouri and Yellowstone Rivers.[--, no data; ADCP, acoustic Doppler current profiler; YOY, young-of-year; RTK, real-time kinematic; GPS, global positioning system; DGPS, differential global positioning sys

Date Upstream river mile Downstream river mile Number of fish relocations (migration) Streamgage Discharge, cubic feet per second Equipment Pro

Lower Missouri River

Spawning

4/3/2012 322.6 321.8 -- Waverly, Missouri 60,800 ADCP Depth and velocity patch m

4/12/2012 322.6 321.8 -- Waverly, Missouri 52,500 Multibeam Multibeam bathymetry ma

4/14/2012 322.6 321.8 -- Waverly, Missouri 51,500 ADCP Depth and velocity patch m

5/1/2012 580.6 579.6 -- Nebraska City, Nebraska 39,600 ADCP Depth and velocity patch m

5/2/2012 580.6 579.6 -- Nebraska City, Nebraska 40,600 Multibeam Multibeam bathymetry ma

Migration

4/26/2012 636.5 635.5 15 Decatur, Nebraska 30,100 ADCP 4 reciprocal ADCP transec

674.7 674 13 Decatur, Nebraska 30,100 ADCP 4 reciprocal ADCP transec

4/27/2012 591.4 590.6 8 Nebraska City, Nebraska 38,000 ADCP 4 reciprocal ADCP transec

592.1 591.7 11 Nebraska City, Nebraska 38,000 ADCP 4 reciprocal ADCP transec

5/3/2012 676.5 675.6 10 Decatur, Nebraska 30,600 ADCP 4 reciprocal ADCP transec

685.3 684 23 Decatur, Nebraska 30,600 ADCP 4 reciprocal ADCP transec

5/4/2012 694.6 693.7 16 Decatur, Nebraska 32,600 ADCP 4 reciprocal ADCP transec

6/1/2012 710.2 709.3 12 Decatur, Nebraska 44,500 ADCP 4 reciprocal ADCP transec

Free-embryo and larvae sampling

4/16/2012 34.3 33.5 -- St Charles, Missouri 166,000 ADCP Depth and velocity patch m

4/17/2012 34.3 33.5 -- St Charles, Missouri 155,000 Multibeam Multibeam bathymetry ma

5/10/2012 33.4 33.2 -- St Charles, Missouri 134,000 ADCP Depth and velocity patch m

5/22/2012 33.4 33.2 -- St Charles, Missouri 75,800 ADCP Depth and velocity patch m

6/26/2012 33.4 33.2 -- St Charles, Missouri 59,500 ADCP Depth and velocity patch m

Age-0/ YOY Sturgeon habitat 

Sturgeon habitat 

5/23/2012 162.7 161 -- Boonville, Missouri 55,600 ADCP Depth and velocity patch m

5/24/2012 162.7 161 -- Boonville, Missouri 55,200 Multibeam Multibeam bathymetry ma

7/10/2012 162.7 161 -- Boonville, Missouri 43,600 ADCP Depth and velocity patch m

7/11/2012 162.7 161 -- Boonville, Missouri 42,500 Multibeam Multibeam bathymetry ma

8/9/2012 214.5 214 -- Boonville, Missouri 41,700 ADCP Depth and velocity patch m

10/4/2012 162.7 161 -- Boonville, Missouri 42,700 ADCP Depth and velocity patch m
Table 3–1. Sturgeon habitat mapping 2012 data collection effort on the Missouri and Yellowstone Rivers.—Continued [--, no data; ADCP, acoustic Doppler current profiler; YOY, young-of-year; RTK, real-time kinematic; GPS, global positioning system; DGPS, differential global positioning sys

Date Upstream river mile Downstream river mile Number of fish relocations (migration) Streamgage Discharge, cubic feet per second Equipment Pro

Habitat use and home range 5/30/2012 582.9 582.5 -- Nebraska City, Nebraska 51,300 ADCP, Multibeam Multibeam bathymetry and 

5/31/2012 638.7 638.3 -- Decatur, Nebraska 43,400 ADCP, Multibeam Multibeam bathymetry and 

10/10/2012 202 200 -- Boonville, Missouri 43,000 ADCP Depth and velocity reach m

Yellowstone River Migration 5/21/2012 8.2 7.2 2 Sidney, Montana 21,600 ADCP 4 reciprocal ADCP transec

5/22/2012 30.2 26.7 13 Sidney, Montana 22,100 ADCP 4 reciprocal ADCP transec

13.7 10.8 6 Sidney, Montana 22,100 ADCP 4 reciprocal ADCP transec

5/23/2012 23.7 20.8 5 Sidney, Montana 19,400 ADCP 4 reciprocal ADCP transec

5/24/2012 23.3 17.1 10 Sidney, Montana 17,100 ADCP 4 reciprocal ADCP transec

20.1 18.5 8 Sidney, Montana 17,100 ADCP 4 reciprocal ADCP transec

5/25/2012 33.3 28.8 17 Sidney, Montana 17,600 ADCP 4 reciprocal ADCP transec

5/29/2012 37.3 34.7 12 Sidney, Montana 20,100 ADCP 4 reciprocal ADCP transec

5/30/2012 29.8 29.3 2 Sidney, Montana 19,200 ADCP 4 reciprocal ADCP transec

11.9 11.1 5 Sidney, Montana 19,200 ADCP 4 reciprocal ADCP transec

5/31/2012 4 3.1 7 Sidney, Montana 18,700 ADCP 4 reciprocal ADCP transec

14.5 10.2 2,6,2 Sidney, Montana 18,700 ADCP 4 reciprocal ADCP transec

6/6/2012 40.2 37.7 7 Sidney, Montana 26,600 ADCP 4 reciprocal ADCP transec

6/7/2012 51 49 12 Sidney, Montana 32,400 ADCP 4 reciprocal ADCP transec

26.2 23.7 4 Sidney, Montana 32,400 ADCP 4 reciprocal ADCP transec

6/11/2012 72.8 67.6 16 Sidney, Montana 29,500 ADCP 4 reciprocal ADCP transec

6/12/2012 62.3 59 12 Sidney, Montana 29,400 ADCP 4 reciprocal ADCP transec

68.3 67.2 6 Sidney, Montana 29,400 ADCP 4 reciprocal ADCP transec

6/13/2012 48.7 48.4 6 Sidney, Montana 30,100 ADCP 4 reciprocal ADCP transec

6/14/2012 11.7 4.4 20 Sidney, Montana 25,700 ADCP 4 reciprocal ADCP transec
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 149

40°54’30”

40°54’40”

41°27’50”

41°28’

95°58’40” 95°58’30” 95°58’20” 95°58’10” 95°58’ 95°57’50”

95°49’40” 95°39’30” 95°49’20” 95°40’10” 95°49’

6/2 /1 0

6/4 /0 8

5/7 /0 8

5/5 /0 8

5/2 /0 8

5/1 /0 8

4/8 /0 8

3/2 7 /0 8

3/2 6 /0 8

3/2 6 /0 8

5/2 1 /1 0

5/11 /1 0

4/3 0 /1 0

5/1 9 /0 8

4/2 1 /0 8

3/3 1 /0 8

11/1 5 /1 0

9/9 /1 0

8/6 /0 8

7/9 /0 8

8/2 9 /1 2

6/2 8 /1 2

5/2 4 /1 2

9/1 5 /1 0

9/2 3 /0 9

9/1 0 /0 9 8/1 0 /0 9

7/3 0 /0 9

7/2 2 /0 9

9/3 0 /0 8

8/1 9 /0 8

7/3 1 /0 8

7/2 2 /0 8

7/1 6 /0 8

10 /11 /11

638.5

582.5

582.5

EXPLANATION

A. Near river mile 638.5

B. Near river mile 582.5

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2010

Universal Transverse Mercator projection, zone 15

River miles from U.S. Army Corps of Engineers, 1960

Discharges on the dates of survey 

May 31, 2012, at the U.S. Geological 

Survey streamgage at Decatur, 

Nebraska, was 43,300 cubic feet per 

second.

0 200 400 600 FEET

0 50 100 150 METERS

Discharges on the dates of survey May 30, 

2012, at the U.S. Geological Survey 

streamgage at Nebraska City, Nebraska, 

was 51,300 cubic feet per second.

10.2

0.9

Depth, in meters Pallid sturgeon location and date—Locations 

of pallid sturgeon PLS08-006 from 2008–12

River mile marker—Number is distance upstream 

from the confluence with the Mississippi River, 

in miles

5/2 4 /1 2

Figure 3–5. Telemetry locations and multibeam bathymetry showing depth at locations used by male pallid sturgeon 

PLS08-006 from 2008–12 near river miles, A, 638.5 and, B, 582.5.
150 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

References Cited

Bonnot, T.W., Wildhaber, M.L., Millspaugh, J.J., DeLonay, 

A.J., Jacobson, R.B., and Bryan, J.L., 2011, Discrete choice 

modeling of shovelnose sturgeon habitat selection in the 

lower Missouri River: Journal of Applied Ichthyology, 

v. 27, no. 2, p. 291–300. [Also available at http://dx.doi.

org/10.1111/j.1439-0426.2010.01637.x.]

Calder, B.R., and Mayer, L.A., 2003, Automatic processing of 

high-rate, high-density multibeam echosounder data: Geochemistry geophysics geosystems, v. 4, no. 6, p. 1–17. [Also 

available at http://dx.doi.org/10.1029/2002GC000486.]

Calder, B.R., and Wells, D., 2007, CUBE user’s manual—Version 1.13: Durham, N.H., University of New Hampshire, 

Center for Coastal and Ocean Mapping, 54 p.

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Simpkins, 

D.G., Wildhaber, M.L., Reuter, J.M., Bonnot, T.W., Chojnacki, K.A., Korschgen, C.E., Mestl, G.E., and Mac, M.J., 

2009, Ecological requirements of pallid sturgeon reproduction and recruitment in the lower Missouri River—A 

research synthesis 2005–08: U.S. Geological Survey OpenFile Report 2009–5201, 59 p. [Also available at http://pubs.

usgs.gov/sir/2009/5201/.]

DeLonay, A.J., Jacobson, R.B., Annis, M.L., Braaten, P.J., 

Chojnacki, K.A., Elliott, C.M., Fuller, D.B., Haas, J.D., 

Haddix, T.M., McElroy, B.J., Mestl, G.E., Papoulias, 

D.M., Rhoten, J.C., and Wildhaber, M.L., 2014, Ecological 

requirements for pallid sturgeon reproduction and recruitment in the Missouri River—Annual report 2011: U.S. Geological Survey Open-File Report 2014–1106, 96 p. [Also 

available at http://dx.doi.org/10.3133/ofr20141106.]

Elliott, C.M., Reuter, J.M., and Jacobson, R.B., 2009, Channel morphodynamics in four reaches of the lower Missouri 

River, 2006–07: U.S. Geological Survey Scientific Investigations Report 2009–5074, 258 p. [Also available at http://

pubs.usgs.gov/sir/2009/5074/.]

Huizinga, R.J., Elliott, C.M., and Jacobson, R.B., 2010, Bathymetric and velocimetric survey and assessment of habitat 

for pallid sturgeon on the Mississippi River in the vicinity 

of the proposed Interstate 70 Bridge at St. Louis, Missouri: 

U.S. Geological Survey Scientific Investigations Report 

2009–5198, 28 p. [Also available at http://pubs.usgs.gov/

sir/2009/5198/.]

Jacobson, R.B., and Berkley, Jim, 2011, Conceptualizing 

and communicating ecological river restoration, in Simon, 

Andrew, Bennet, S.J., and Castro, J.M., eds., Stream restoration in dynamic fluvial systems—Scientific approaches, 

analyses and tools, Volume 194: American Geophysical 

Union, Geophysical Monograph 194, p. 9–28. [Also available at http://dx.doi.org/ 10.1029/2010GM000967.]

Jacobson, R.B., Johnson, H.E., III, and Dietsch, B.J., 2009, 

Hydrodynamic simulations of physical aquatic habitat 

availability for pallid sturgeon in the lower Missouri River, 

at Yankton, South Dakota, Kenslers Bend, Nebraska, 

Little Sioux, Iowa, and Miami, Missouri, 2006–07: 

U.S. Geological Survey Scientific Investigations Report 

2009–5058, 67 p. [Also available at http://pubs.usgs.gov/

sir/2009/5058/.]

McElroy, Brandon, Delonay, A.J., and Jacobson, R.B., 2012, 

Optimum swimming pathways of fish spawning migrations 

in rivers: Ecology, v. 93, no. 1, p. 29–34. [Also available at 

http://www.jstor.org/stable/23144018.]

RD Instruments, 2003, WinRiver user’s guide: Poway, Calif., 

RD Instruments, Inc., 144 p.

Reuter, J.M., Jacobson, R.B., Elliott, C.M., Johnson, H.E., III, 

and DeLonay, A.J., 2008, Hydraulic and substrate maps of 

reaches used by sturgeon (Genus Scaphirhynchus) in the 

lower Missouri River, 2005–07: U.S. Geological Survey 

Data Series 386, 442 p. [Also available at http://pubs.usgs.

gov/ds/386/.]

Reuter, J.M., Jacobson, R.B., Elliott, C.M., and DeLonay, A.J., 

2009, Assessment of lower Missouri River physical aquatic 

habitat and its use by adult sturgeon (genus Scaphirhynchus) 2005–07: U.S. Geological Survey Scientific Investigations Report 2009–5121, 81 p. [Also available at http://

pubs.er.usgs.gov/usgspubs/sir/sir20095121.]
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 151

Appendix 4. Migration Pathways, Habitat Use, and Reproduction of Pallid 

Sturgeon in the Yellowstone River, 2012

Braaten and others, 2012). Currently, the limited availability of 

free-flowing riverine habitat between spawning locations and 

the downstream reservoir (Lake Sakakawea, North Dakota) is 

one hypothesis for recruitment failure for pallid sturgeon in the 

fragmented upper Missouri River basin (Kynard and others, 

2007; Braaten and others, 2008; Braaten and others, 2012).

Several alternatives for providing pallid sturgeon passage 

through the reach affected by Intake Dam have been proposed, 

but construction of a bypass channel around Intake Dam has 

emerged as a preferred design alternative (U.S. Bureau of 

Reclamation, 2014). In this design, a 2.9-mi long side channel 

approximately 150–250 feet (ft) wide would be constructed 

around Intake Dam (U.S. Army Corps of Engineers, 2012). 

The downstream entrance of the constructed side channel 

would join the main stem river on the south bank of the river 

immediately downstream from the existing dam. This alternative also includes construction of a new concrete dam slightly 

upstream from the existing rock dam. Although initial designs 

for the bypass channel alternative have been developed, 

limited information on migration patterns, side channel use 

and avoidance, swimming abilities, and depths and velocities negotiated by pallid sturgeon is available to guide design 

specifications for the proposed bypass channel relative to the 

needs of pallid sturgeon.

Scope and Objectives

In 2011, collaborative investigations between the 

U.S. Geological Survey (USGS) and Montana Fish, Wildlife 

and Parks were initiated to examine multiple facets of pallid 

sturgeon migrations and reproductive biology in the Yellowstone River (Braaten and others, 2015). As a pilot project 

in 2011, the study examined migration pathways of pallid 

sturgeon (for example, main-channel and side-channel routes 

used by migrating individuals), depths and velocities negotiated by migrating pallid sturgeon, the periodicity of pallid 

sturgeon arrival at Intake Dam, migration approach pathways 

to Intake Dam, and spawning of pallid sturgeon in the Yellowstone River. Work in 2012 expanded on the 2011 pilot project 

and included multifaceted objectives focused on examining 

migrations of pallid sturgeon to inform engineering design 

specifications for fish passage alternatives at Intake Dam, and 

examining reproductive biology of pallid sturgeon in a natural 

river environment.

The first objective was to determine the migrations and 

migration pathways of telemetered pallid sturgeon in the Yellowstone River. This objective provided information on the 

spatial and temporal extant of migrations in the Yellowstone 

River, depths and velocities negotiated by migrating individuals, use or avoidance of side channels during migrations, and 

pallid sturgeon migration pathways as individuals approached 

Intake Dam.

Background

The upper Missouri River basin including the lower Yellowstone River and Missouri River between Fort Peck Dam 

and Lake Sakakawea contains a wild stock of pallid sturgeon 

(Scaphirhynchus albus) that is estimated to have declined from 

nearly 1,000 individuals in the 1960s to fewer than 150 individuals at present (2012). The wild stock is composed of 

large adults (>1,000 millimeters [mm]; U.S. Fish and Wildlife 

Service, 2007) as wild-produced small individuals have not 

been detected during decades of netting efforts. The lack of 

small and young individuals in the wild population provides 

evidence of complete recruitment collapse for 50 or more 

years (Braaten and others, 2015). Multiple factors including river fragmentation and alteration of discharge and water 

temperature regimes for the Missouri River, and fragmentation of the Yellowstone River have been implicated as agents 

of recruitment failure, which negatively affects reproductive 

success and survival of pallid sturgeon (U.S. Fish and Wildlife 

Service, 1993, 2000, 2003).

The Yellowstone River is a focal point for pallid sturgeon 

research and restoration activities within the upper Missouri 

River basin. Unlike other river reaches throughout the range of 

pallid sturgeon, the Yellowstone River retains natural channel morphology and relatively natural hydrologic and thermal 

regimes that support spawning of wild-stock pallid sturgeon 

(Fuller and others, 2008; Fuller and Braaten, 2013). On this 

basis, the Yellowstone River provides the rare opportunity 

to understand reproductive dynamics of pallid sturgeon in a 

near-natural environment and provides inferences on natural 

reproductive processes for altered-river reaches. Although 

spawning is known to take place in the Yellowstone River, 

fragmentation of the system is hypothesized to limit recruitment from natural-spawning events through a combination of 

factors involving few spawning adults, barriers to migration, 

poor spawning success, and early life history mortality. Pallid 

sturgeon migration on the Yellowstone River is unrestricted for 

the lower 73 miles (mi) of the river upstream from the confluence with the Upper Missouri River. Upstream access beyond 

that point is impeded by Lower Yellowstone Intake Diversion Dam (hereinafter referred to as, Intake Dam), a rock and 

boulder dam constructed in the early 1900s that spans the width 

of the river. Pallid sturgeon will ascend the Yellowstone River 

to Intake Dam (Fuller and others, 2008; Fuller and Braaten, 

2014), but passage over or through the dam has not been 

documented by wild adults in recent studies. Rehabilitation of 

the Yellowstone River has focused on creating passage through 

the reach affected by the dam as a means of facilitating access 

to potential upstream spawning areas. Access to and spawning 

in upstream reaches of the Yellowstone River will increase the 

length of free-flowing riverine habitat available to drifting free 

embryos and larvae following hatch (Braaten and others, 2008; 
152 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

The second objective was to determine the spatial and 

temporal dynamics of spawning in the Yellowstone River. Earlier studies documented spawning and provided inferences on 

the timing and location of spawning events in the Yellowstone 

River (Fuller and others, 2008; Braaten and others, 2015); 

however, the specific location(s) and date(s) of spawning had 

not been ascertained.

The third objective was to verify that embryos hatch by 

collecting free embryos in the Yellowstone River because 

pallid sturgeon are known to spawn in the Yellowstone River. 

Verification of hatch and drift entry have not been demonstrated as no pallid sturgeon embryos, free embryos, or larvae 

have been collected in the Yellowstone River.

Methods

A total of 41 wild adult male and female pallid sturgeon 

composed the telemetered research population in 2012. The 

telemetered population included individuals from earlier 

studies that carried radio transmitters, individuals that had 

expired or expiring transmitters from earlier studies that were 

reimplanted with new transmitters, and individuals that had 

not been previously implanted with radio transmitters. Three 

females (codes 30, 35, and 36) were identified as potential 

spawn candidates for 2012 based on the presence of black 

eggs and elevated reproductive hormones (testosterone [T] 

and estradiol [E2]) when assessed on April 25–26, 2012 (code 

30, T=32.83 nanograms per milliliter [ng/mL], E2=4.58 ng/

mL; code 35, T=49.9 ng/mL, E2=4.63 ng/mL; code 36, 

T=87.19 ng/mL, E2=8.47 ng/mL).

Manual tracking by boat of the Yellowstone River and 

Missouri River downstream from the Yellowstone River 

confluence was initiated in April. Tracking was done using 

open watercraft (6 meters (m) in length) with a bow mounted 

4-element Yagi antenna. Pallid sturgeon relocation points and 

associated environmental point attributes (depth, temperature, and conductivity) were recorded on a highly customized 

mobile mapping and electronic data-collection application 

linked to a differential global positioning system (DGPS). The 

DGPS was located in the center of the watercraft. Location 

accuracy in the Yellowstone River, estimated from locating 

tags at known positions, was about one boat length. Locations 

characterized pallid sturgeon either maintaining a stationary point in the river or depicted a continuous series of point 

locations characterizing upstream migration pathways for 

actively migrating individuals. Quantification of depths and 

velocities at migration points and in the channel cross-section 

containing the migration point was executed using an acoustic 

Doppler current profiler (ADCP) linked to DGPS. Automated 

ground-based logging stations were deployed in the Yellowstone River (river mile [RM] 0.75, 7.0, 16.5, 37.0, 72.8) and in 

the Missouri River to complement manual tracking and obtain 

additional information on migrations and movements among 

river reaches.

Sampling for pallid sturgeon free embryos and larvae 

was done downstream from suspected spawning sites (see 

below) in the lower reaches of the Yellowstone River. The 

sampling apparatus consisted of a 3.0-m long tapered rectangular net (1-mm mesh) affixed to a rectangular net-mouth 

frame (0.75-m width, 0.5-m height). Two sounding weights 

(4.5 kilograms [kg]) were attached to the net frame. Following 

Braaten and others (2010), one pair of nets was fished simultaneously during deployment, and one net each deployed on 

the port and starboard sides of the boat. Nets were fished on 

the river bed. Sample contents were transferred to black pans, 

and all Acipenseriformes (Scaphirhynchus spp. and paddlefish 

Polyodon spathula) eggs, embryos, free embryos, and larvae 

extracted from the detritus were preserved immediately in 

95-percent ethanol. All Acipenserifomes free embryos and 

larvae were genetically analyzed to confirm species identity 

as paddlefish, shovelnose sturgeon (Scaphirhynchus platorynchus), or pallid sturgeon.

Results

Flow conditions in the Yellowstone River during 2012 

were lower than the 1911–2011 trends as mean discharge during April (9,563 cubic feet per second [ft3

/s]), May (15,643 ft3/s), 

June (23,957 ft3/s) and July (10,761ft3/s) represented 89 percent, 85 percent, 62 percent and 47 percent, respectively, of 

the long-term means (fig. 4–1). There were periods of elevated 

flow conditions in late April, mid- to late May, and early June; 

the maximum discharge (39,600 ft3/s) happened on June 9. 

There were pronounced fluctuations in water temperature 

throughout the season as temperature declines of as much as 

8 degrees Celsius (oC) and rapidly warming over short-term 

intervals (several days to two weeks) were noted in several 

instances. Migrations of pallid sturgeon into the Yellowstone 

River were initiated by early April, increased during late April 

and May, and reached a maximum (90 percent of the telemetered population) in late May (fig. 4–1). Use of the Yellowstone River remained high through mid-June, then declined as 

pallid sturgeon emigrated from the Yellowstone River. 

The spatial extent and timing of migrations in the Yellowstone River during 2012 varied markedly among individuals and by reproductive status. Manual tracking complemented 

with detections from the telemetry logging station at Intake 

identified that five male pallid sturgeon (codes 42, 52, 69, 

72, and 76) migrated to Intake Dam but did not pass over 

the dam (fig. 4–2). No telemetered female pallid sturgeon 

were detected at Intake Dam. Code 42 initiated a late April 

upstream migration as discharge increased and reached Intake 

Dam on May 2. Upstream migrations by codes 52, 69, and 72 

were sustained during the increasing hydrograph in early June 

with code 52 arriving at Intake Dam on June 9 and code 72 

arriving at Intake Dam on June 13. Code 69 migrated downstream as discharge receded, and then ascended the river to 

Intake on June 22. Code 76 remained in the lower Yellowstone 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 153

River through early June, migrated upstream through midJune, and reached Intake on June 22. All detected pallid 

sturgeon remained in close proximity to the dam for 1–2 days 

prior to initiating downstream migrations.

Although five male pallid sturgeon migrated to Intake 

Dam during 2012, most telemetered male pallid sturgeon 

migrated into and resided in the lower or middle reaches of the 

Yellowstone River; for example, male codes 10, 11, 21, 22, 

51, and 83 exhibited maximum upstream detection locations 

between RM 20–40 of the Yellowstone River (fig. 4–3). A 

second group of 18 male pallid sturgeon ascended less than 

20 RM (fig. 4–3); however, whereas upstream migrations 

of numerous males were restricted to the lower and middle 

reaches of the Yellowstone River, many males (for example, 

codes 15, 22, 46, 48, 49, 50, 51, 68, 75, and 77) were in the 

Missouri River upstream from the Yellowstone River confluence (as much as 180 RM) prior to Yellowstone River entry.

Gravid females again exhibited the characteristic complex migration pattern typical of the Yellowstone River. The 

usual pattern for females is to make successive, long distance 

upstream and downstream movements in the Yellowstone 

River, typically moving downstream into the Upper Missouri 

River, before stopping to spawn near an aggregation of males 

in the Yellowstone River. Code 30 exhibited pronounced 

pre-spawn migrations as this individual initially migrated 

nearly 40 miles (mi) into the Missouri River near Culbertson, 

Montana, between April 26 and May 6, resided above the 

Culbertson, Mont., logging station for 5 days, then migrated 

downstream during May 11–15 (fig. 4–4). Following the Missouri River descent, code 30 entered the Yellowstone River 

on May 22 and exhibited several upstream and downstream 

migrations with the most upstream migration persisting to 

Yellowstone RM 63.8 on June 9. Similar to female code 30, 

female code 35 exhibited extensive upstream and downstream 

migrations as upstream migrations were detected to RM 27.2 

on May 22, RM 26.3 on June 6, and RM 37.0 on June 19 

(fig. 4–4). Female code 36 similarly exhibited upstream and 

downstream migrations with a maximum upstream detection 

point to RM 37.2 on May 23 (fig. 4–4).

Based on mean daily river locations in the Yellowstone 

River and Missouri River, the total distance migrated by males 

(the sum of all upstream and downstream movements) and 

females known to be gravid was estimated for the pre-spawn 

period. For males, the pre-spawn period was defined as the 

date and location of initial detection in April or May extending to mid-June when spawning activity was observed in the 

lower Yellowstone River and many males were included in the 

spawning aggregation (see below). A similar procedure was 

used for female codes 30 and 35, but the pre-spawn period 

for code 36 was terminated at June 1 as this female likely 

spawned close to this date (see below). The estimated prespawn migration distance for the 29 males assessed averaged 

155 mi (range 44–470 mi). Code 82 was the least migratory 

male as this individual remained primarily in the lower 10 mi 

rol15-EMSB0-0040 Delonay Appendix Figure 4–1

Month

Apr. May June July Aug. 

0

10

20

30

40

50

60

70

80

90

100

0

10,000

20,000

30,000

40,000

6

8

10

12

14

16

18

20

22

24

26

28

Pallid sturgeon 

Discharge

Water temperature

Telemetered pallid sturgeon in the Yellowstone River, in percent

Yellowstone River discharge, in cubic feet per second

Mean daily water temperature, in degrees Celsius

EXPLANATION

Figure 4–1. Percent of telemetered pallid sturgeon detected, discharge, and mean daily water temperature of the 

Yellowstone River, April–August 2012.
154 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

0

10

20

30

40

50

60

70

80

Code 42

Code 52

Code 72

Code 76

Code 69

Month

Apr. May June July Aug. 

Mean daily discharge, in cubic feet per second

0

10,000

20,000

30,000

40,000

50,000

5

10

15

20

25

30

Yellowstone River location, in miles

Mean daily water temperature, in degrees Celsius

Discharge

Temperature

EXPLANATION

EXPLANATION

A

B

Intake Diversion Dam location; river mile 72.8

Figure 4–2. Data for five telemetered pallid sturgeon (codes 42, 52, 69, 72, and 76) migrating to Intake Dam on 

the Yellowstone River, April–August 2012. A, location and B, mean daily discharge and water temperature.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 155

rol15-EMSB0-0040 Delonay Appendix Figure 4–3

EXPLANATION

EXPLANATION EXPLANATION

Mean daily Yellowstone River location, in miles

0

10

20

30

40

Code 10

Code 11

Code 21

Mean daily Yellowstone River location, in miles

0

5

10

15

20

25

Code 15

Code 16

Code 17

Month

Apr. May June July Aug. 

Mean daily Yellowstone River location, in miles

0

5

10

15

20

25

Month

Apr. May June July Aug. 

Code 45

Code 46

Code 22

Code 51

Code 83

Code 48

Code 49

Code 50

Code 55

EXPLANATION

EXPLANATION

Code 60

Code 68

Code 73

Code 74

Code 75

EXPLANATION

Code 77

Code 81

Code 82

Code 92

A B

C D

E F

Figure 4–3. Locations of telemetered male pallid sturgeon exhibiting migrations in the Yellowstone River, April–August 2012. A, 

codes 10, 11, and 21 ascending upstream from river mile 20; B, codes 22, 51, and 83 ascending upstream from river mile 20; C, codes 

15–17, 45, and 46 remaining downstream of river mile 20; D, codes 48–50 and 55 remaining downstream from river mile 20; E, codes 60, 

68, and 73–75 remaining downstream from river mile 20; and F, codes 77, 81, 82, and 92 remaining downstream from river mile 20.
156 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

rol15-EMSB0-0040 Delonay Appendix Figure 4–4

EXPLANATION

Mean daily Yellowstone River location, in miles

0

10

20

30

40

50

60

70

Mean daily Missouri River location, in miles

1,570

1,580

1,590

1,600

1,610

1,620

1,630

Yellowstone River 

location

Missouri River 

location

Mean daily Yellowstone River location, in miles 

0

10

20

30

40

50

60

70

Yellowstone River location

Month

Apr. May June July Aug. 

Mean daily Yellowstone River location, in miles

0

10

20

30

40

50

60

70

Mean daily Missouri River location, in miles

1,570

1,575

1,580

1,585

1,590

1,595

1,600

Yellowstone River location

Missouri River location

B. Code 35

C. Code 36

A. Code 30

EXPLANATION

EXPLANATION

Figure 4–4. Mean daily locations of telemetered female pallid sturgeon exhibiting 

migrations in the Yellowstone River and Missouri River upstream from the confluence 

with the Yellowstone River, April–August, 2012. A, code 30; B, code 35; and C, code 36.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 157

of the Yellowstone River. Male code 50 exhibited the greatest 

migratory distance as this individual initially occupied the Yellowstone River in mid-April, exhibited extensive migrations 

in the Missouri River during late April and early May that 

extended to RM 1,760 (approximately 10 miles downstream 

from Fort Peck Dam), then re-entered the Yellowstone River 

and remained in the lower reaches. Total migration distances 

were categorized into groups including fish that migrated less 

than (<) 100 mi, 101–150 mi, 151–200 mi, 201–250 mi, and 

greater than (>) 250 mi. Telemetered male pallid sturgeon 

assigned to migration distance categories at 31 percent, 21 percent, 28 percent, 10 percent, and 10 percent of the total tagged 

population, respectively. A crude approximation of the average 

pre-spawn migration distance for gravid females was 218 mi. 

Female code 30 exhibited the greatest migration distance 

(estimated 289 mi) as this female used the Missouri River 

prior to Yellowstone River entry. Female code 35 traversed an 

estimated 205 mi as migrations were restricted to the Yellowstone River. Code 36 migrated through an estimated 161 mi 

with migrations primarily restricted to the Yellowstone River. 

It should be noted that the migration distances are likely conservative as the estimates are based on mean daily locations 

and do not include other movements that may have happened 

between relocation dates.

Migration Pathways

Migration pathways for eight males (codes 16, 42, 51, 

52, 69, 72, 76, 92), two gravid females (codes 30, 36), and 

one non-gravid female (code 37) were obtained between April 

30 and June 13 throughout much of the Yellowstone River. 

Of the five male pallid sturgeon that migrated to Intake Dam, 

intensive tracking of codes 52 and 76 characterized pathways 

traversed as these individuals approached Intake Dam. On 

June 9, code 52 was initially located at RM 67.6 (fig. 4–5). 

After marking this individual at RM 69.5 (1:57 p.m.), code 52 

entered a small side channel (approximately 400-m-long) on 

the inside bend of the main channel and proceeded upstream 

in the side channel. Code 52 continued moving upstream and 

successfully traversed the upstream inlet of the side channel 

at 2:45 p.m. After moving along the north bank of the main 

river channel from 3:31 to 4:27 p.m., code 52 crossed the 

channel and approached Intake Dam along the south bank 

of the river where upstream progression was observed until 

9:42 p.m. Thereafter, slight downstream movement towards 

mid-river was noted for the last location at 9:45 p.m. Code 76 

was first located downstream from Intake Dam at RM 71.8 

(10:05 a.m.), and the approach pathway to the dam included 

locations extending from the south bank of the river to the 

southern one-half of the river channel (fig. 4–6). Upstream 

movement was maintained by code 76 until approximately 

5:00 p.m.; thereafter, relocations for code 76 remained clustered below the dam in the mid-channel.

Under moderate flow conditions in the Yellowstone 

River during 2012, pallid sturgeon exhibited migration 

pathways primarily through main channel habitats; however, migrations through braided channel configurations and 

primary or secondary side channels were also noted. For 

example, main channel migration pathways were primary 

routes used by code 16 (May 17), code 30 (June 6), code 36 

(May 23), code 42 (April 30), code 51 (May 21), code 72 

(May 23) and code 69 (June 8) as side channels within the 

migration corridor received limited use (fig. 4–7 to 4–21). In 

other cases, use of side channels or split channel configurations by migrating pallid sturgeon were observed; however, 

use was not consistent among individuals. For example, code 

36 and code 37 were located on May 22, moving in close 

proximity through the same river bend on the same day. Their 

migration pathways were, therefore, assessed under identical conditions (fig. 4–11). Early in the migration (from about 

RM 18–20), both pallid sturgeon used a similar main-channel 

migration pathway but did not use the short (0.5-mi long) or 

long (1.75-mi long) side channels available within this reach. 

At about RM 20, commonality in the migration pathway 

diverged as code 36 and code 37 used opposite channels 

in the split channel configuration. Additional variability in 

side channel use was noted between code 36 and code 69. 

Specifically, on May 23 at a discharge of 19,300 ft3

/s, code 

36 migrated past the downstream entrance of a side channel 

joining the river at RM 36.5 and proceeded upstream along a 

main channel pathway (fig. 4–12). At a similar discharge of 

20,400 ft3/s on June 5, code 69 was first located (2:21 p.m.) 

emerging from the upstream inlet of the same side channel 

(fig. 4–14) that was not used by code 36; thus, under similar 

discharge conditions, the 1.1-mile long side channel was used 

as a migration route by code 69 but not used by code 36. The 

migration pathway of code 69 was also observed through a 

braided channel configuration on June 6 (fig. 4–16). Passage 

through the 2.4-mi-long braided channel was successful as 

code 69 was relocated upstream on June 7.

Upstream movement in a long (1.7 mi) side channel near 

RM 63.7–63.8 was noted for code 30 on June 9. After moving 

upstream a distance of approximately 1.2 mi, code 30 turned 

around and swam downstream out of the side channel into 

the main channel. Failure of code 30 to completely negotiate 

the entire length of the side channel may have been related 

to unsuitable hydraulic conditions in the side channel. Alternatively, upstream migration behavior of code 30 may have 

been compromised by boat operations in shallow water while 

attempting to obtain an accurate telemetry location.
rol15-EMSB0-0040 Delonay Appendix Figure 4–5

7:43 PM 8:01 PM 7:15 PM 6:20 PM 1:22 PM

9:36 PM 9:39 PM 9:03 PM

8:13 PM

7:33 PM

7:06 PM

4:27 PM

3:31 PM

1:57 PM

12:16 PM

11:24 AM

12:50 PM

71 70

73

69

74

72

104°33’ 104°32’ 104°31’ 104°30’ 104°29’ 104°28’ 

47°18’

47°17’15”47°16’30”

River miles from Y

Pallid sturgeon telemetry on June 9, 2012, at a discharge of 39,600 cubic feet per second at the U.S. Geological Survey streamgage 6329500 Yellowstone River near Sidney, Montana. 

0 2,000 FEET 1,0000 250 500 METERS

EXPLANATION

Pallid sturgeon code 52Yellowstone River mile marker—Number is 

distance upstream from the Missouri River confluence, in miles 

Digital imagery from U.S. Department of Agriculture National Agriculture Imagery Program digital data, 2009Universal Transverse Mercator projection, zone 15

71

Figure 4–5. Migration pathway of male pallid sturgeon code 52 in the Yellowstone River approaching Intake Dam, June 9, 2012.
rol15-EMSB0-0040 Delonay Appendix Figure 4–6

104°32’20” 104°32’ 104°31’40” 104°31’20” 104°31’ 104°30’40” 104°30’20” 

47°17’15”

47°17’

47°16’45”

47°16’30”

8:01 PM

7:43 PM 7:15 PM6:51 PM 5:58 PM

5:06 PM

4:47 PM

3:52 PM

3:23 PM

1:47 PM

1:04 PM

9:42 PM

9:35 PM

9:03 PM

8:54 PM

8:33 PM

8:13 PM

7:52 PM

7:33 PM

7:06 

12:16 PM

11:24 AM 10:43 AM

10:05 AM

73

72

River miles from Y

Pallid sturgeon telemetry on June 9, 2012, and June 22, 2012, at discharges of 39,600 and 23,600 cubic feet per second at the U.S. Geological Survey streamgage 6329500 Yellowstone River near Sidney, Montana.

EXPLANATION

Digital imagery from U.S. Department of Agriculture National Agriculture Imagery Program digital data, 2009

0 1,0000 250

2,000 FEET

500 METERS

Pallid sturgeon code

73 Yellowstone River mile marker—Number is 

distance upstream from the Missouri River confluence, in miles

52 on June 9, 201276 on June 22, 2012

Figure 4–6. Migration pathways of male pallid sturgeon codes 52 and 76 in the Yellowstone River approaching Intake Dam, June 9 and 22, 2012.
160 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

104°20’30” 104°20’ 104°19’30” 104°19’

47°27’

47°26’20”

47°26’

47°26’40”

47°27’20”

11:50 AM

54

3:53 PM

4:25 PM

4:50 PM

5:22 PM

0 100 200 METERS

0 500 1,000 FEET River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on April 30, 2012, 

at a discharge of 19,600 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 42

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

54

Figure 4–7. Pallid sturgeon code 42 telemetry locations in the Yellowstone River, April 30, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 161

103°58’30”

47°56’30”

47°56’

47°56’45”

47°55’30”

47°56’15”

47°55’45”

103°58’ 103°57’30” 103°57’

!.

!.

4:27 PM

5:05 PM

5:50 PM

6:09 PM

6:41 PM

7:15 PM

0 100 200 METERS

0 500 1,000 FEET River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 17, 2012, 

at a discharge of 10,800 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2011

EXPLANATION

Pallid sturgeon code 16

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

4 4 3

Figure 4–8. Pallid sturgeon code 16 telemetry locations in the Yellowstone River, May 17, 2012.
162 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

104°08’15”

47°42’

104°09’ 104°07’30” 104°06’45” 104°06’ 104°05’15”

47°39’45”

47°42’45”

47°41’15”

47°40’30”

!.

!.

26

27

12:43 PM

1:31 PM

2:24 PM 28 2:56 PM

1:57 PM

29

3:33 PM

4:02 PM

4:23 PM

5:31 PM 5:14 PM

5:52 PM

6:16 PM

30

6:31 PM

0 200 400 METERS

0 1,000 2,000 FEET River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 21, 2012, 

at a discharge of 21,400 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 51

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

29

Figure 4–9. Pallid sturgeon code 51 telemetry locations in the Yellowstone River, May 21, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 163

104°00’40” 104°00’05” 103°59’30” 103°58’55” 103°58’20”

47°48’45”

47°49’20”

47°49’55”

3:51 PM

13

12

4:24 PM

5:09 PM

5:33 PM

6:03 PM

6:35 PM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 21, 2012, 

at a discharge of 21,400 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 92

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

13

0 100 200 METERS

0 500 1,000 FEET

Figure 4–10. Pallid sturgeon code 92 telemetry locations in the Yellowstone River, May 21, 2012.
164 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

47°48’

104°06’

47°45’

47°47’15”

47°46’30”

47°45’45”

104°05’15” 104°04’30” 104°03’45” 104°03’ 104°02’15”

9:41 AM

.

10:33 AM

10:58 AM

11:33 AM

9:24 AM

12:02 PM

12:24 PM 10:46 AM

11:22 AM

11:44 AM

12:54 PM

12:12 PM

12:58 PM

2:05 PM

3:45 PM

2:26 PM

4:21 PM 3:58 PM 4:48 PM

5:37 PM

23

22

21

20

19

18

17

16

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 22, 2012, 

at a discharge of 21,900 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

0 250 500 METERS

0 1,000 2,000 FEET

EXPLANATION

Pallid sturgeon code

23 Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

36

37

Figure 4–11. Pallid sturgeon codes 36 and 37 telemetry locations in the Yellowstone River, May 22, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 165

47°36’45”

104°12’45”

47°37’30”

104°12’ 104°11’15” 104°10’30”

11:06 AM

11:35 AM

11:59 AM

12:22 PM

12:46 PM

1:08 PM

1:26 PM

1:46 PM

2:20 PM 2:40 PM

3:09 PM

3:33 PM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 23, 2012, 

at a discharge of 19,300 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon rcode 36

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

37

0 100 200 METERS

0 500 1,000 FEET

37

36

35

Figure 4–12. Pallid sturgeon code 36 telemetry locations in the Yellowstone River, May 23, 2012.
166 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

104°12’

47°38’15”

47°41’15”

47°39’

47°40’30”

47°39’45”

104°11’ 104°10’ 104°09’ 104°08’ 104°07’

12:21 PM

9:59 AM

10:28 AM 11:17 AM

11:07 AM 11:52 AM

11:26 AM 12:35 PM

1:05 PM

1:12 PM

2:04 PM

2:24 PM

2:57 PM

3:12 PM

3:53 PM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on May 23, 2012, 

at a discharge of 19,300 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 72

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

33

0 200 400 METERS

0 1,000 2,000 FEET

32

33

30

31

Figure 4–13. Pallid sturgeon code 72 telemetry locations in the Yellowstone River, May 23, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 167

4:26 PM

4:03 PM

3:20 PM

2:56 PM

2:41 PM

1:41 PM

6:43 PM

6:00 PM

5:23 PM

4:53 PM

4:00 PM

3:33 PM

3:24 PM

12:40 PM 11:32 AM

6:43 PM

6:00 PM

5:23 PM

4:53 PM

4:24 PM

3:33 PM

3:24 PM

2:21 PM

4:26 PM

4:03 PM

3:41 PM

51

50

1:22 PM

1:41 PM

2:04 PM

2:41 PM

2:56 PM

3:20 PM

40

39

38

37

39

41

40

43

42

44

45

46

47

49

50

38

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on June 5, 2012, and June 6, 2012, at discharges 

of 20,400 and 26,500 cubic feet per second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 69

Yellowstone River mile marker—Number is distance 

upstream from the Missouri River confluence, in miles

53

48

104°18’ 104°16’ 104°14’ 104°12’

47°36’

47°34’

47°32’

47°30’

47°28’

0 250 500 METERS

0 1,000 2,000 FEET

53

52

June 5, 2012

June 6, 2012

Figure 4–14. Pallid sturgeon code 69 telemetry locations in the Yellowstone River, June 5–6, 2012.
168 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

104°06’45”

47°42’45”

47°44’15”

47°43’30”

104°06’ 104°05’15” 104°04’30” 104°03’45”

47°45’

4:21 PM

11:21 AM

1:16 AM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on June 6, 2012, 

at a discharge of 26,500 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 30

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

26

0 200 400 METERS

0 1,000 2,000 FEET

26

22

23

24

2:39 PM

25

3:17 PM

Figure 4–15. Pallid sturgeon code 30 telemetry locations in the Yellowstone River, June 6, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 169

104°24’

47°21’45”

47°23’15”

47°22’30”

104°23’15” 104°22’30” 104°21’45”

11:39 AM

59

12:35 PM

1:00 PM

1:48 PM

2:04 PM

2:39 PM

2:57 PM

3:32 PM

60

61

3:54 PM

62

4:34 PM

5:39 PM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on June 7, 2012, 

at a discharge of 32,300 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 69

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

62

0 100 200 METERS

0 500 1,000 FEET

Figure 4–16. Pallid sturgeon code 69 telemetry locations in the Yellowstone River, June 7, 2012.
170 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

104°28’

47°19’

47°18’30”

47°19’30”

104°27’30” 104°27’ 104°26’30”

67

68

10:45 AM

11:20 AM

10:40 AM

9:44 AM

9:10 AM

7:39 AM

8:21 AM

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on June 8, 2012, 

at a discharge of 36,500 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 69

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

68

0 100 200 METERS

0 500 1,000 FEET

Figure 4–17. Pallid sturgeon code 69 telemetry locations in the Yellowstone River, June 8, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 171

104°02’

47°54’

47°52’

47°55’

47°50’

47°53’

47°51’

104°00’ 103°58’ 103°56’

12:43 PM

!.

1:24 PM1:36 PM

1:10 PM

2:07 PM

5 6 7

5:29 PM

8 9

10

6:12 PM

6:00 PM

6:38 PM

6:53 PM

7:13 PM

7:32 PM

7:55 PM

7:37 PM

8:00 PM

8:08 PM

8:46 PM

9:31 PM

10:06 PM

10:26 PM

11

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on June 13, 2012, 

at a discharge of 30,000 cubic feet per 

second at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River 

near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 30

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

11

0 500 1,000 METERS

0 1,500 3,000 FEET

Figure 4–18. Pallid sturgeon code 30 telemetry locations in the Yellowstone River, June 13, 2012.
172 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

103°59’15”

47°51’30”

47°52’

47°55’

47°53’30”

47°53’

47°52’30”

103°58’30” 103°57’45” 103°57’ 103°56’15”

6/12/2012

6/9/2012

6/13/2012

5/17/2012

4/10/2012

5/16/2012

5/15/2012

River miles from Yellowstone River Cumulative Study, 2001

(Applied Geomorphology, 2004)

Pallid sturgeon telemetry on April 10, 2012– 

June 21, 2012, at discharges varying from 

8,300–39,600 cubic feet per second at the 

U.S. Geological Survey streamgage 6329500 

Yellowstone River near Sidney, Montana.

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2009

EXPLANATION

Pallid sturgeon code 83

Yellowstone River mile marker—Number is 

distance upstream from the Missouri River 

confluence, in miles

99 8 7 6

0 250 500 METERS

0 1,000 2,000 FEET

Figure 4–19. Pallid sturgeon code 83 telemetry locations in the Yellowstone River, April 10–June 21, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 173

Depth, in meters

1 2 3 4 5 6 7 8 9

Frequency, in percent

0

2

4

6

8

10

12

14

Availability mean = 2.9 meters

Use mean = 2.8 meters

Average velocity, in meters per second

0 0.5 1.0 1.5 2.0 2.5 3.0

Frequency, in percent

0

2

4

6

8

10

12

14

Availability mean = 1.13 meters per second

Use mean = 1.16 meters per second

EXPLANATION

Available 

Used 

A

B

Figure 4–20. Depths and depth-averaged velocities used by and available to migrating pallid 

sturgeon, Yellowstone River, 2012.
174 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Code 51

RM 29.5

5/21/2012

Depth, in meters

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency, in percent

0

2

4

6

8

10

12

14

16

18

Code 72

RM 29.5

5/23/2012

Depth, in meters

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency, in percent

0

2

4

6

8

10

12

14

16

18

Average velocity, in meters per second

0 0.5 1.0 1.5 2.0 2.5 3.0

Frequency, in percent

0

2

4

6

8

10

12

14

Code 51

RM 29.5

5/21/2012

Code 72

RM 29.5

5/23/2012

Average velocity, in meters per second

0 0.5 1.0 1.5 2.0 2.5 3.0

Frequency, in percent

0

2

4

6

8

10

12

14

Available

Used

River mile 

EXPLANATION

RM

5/21 5:52 PM

5/23 11:26 AM

5/21 5:31 PM 5/23 11:52 AM

5/23 11:17 AM

5/21 5:14 PM

Map images are the intellectual property of Esri and 

is used herein under license. Copyright © 2015 Esri 

and its licensors. All rights reserved.

29.5

5/21 5:52 PM

5/23 11:26 AM

5/21 5:31 PM 5/23 11:52 AM

5/23 11:17 AM

5/21 5:14 PM

29.5

0 100 200 METERS

0 500 1,000 FEET

Discharges at the U.S. Geological Survey 

streamgage 6329500 Yellowstone River near 

Sidney, Montana, in cubic feet per second:

5/21/2012 = 21,400

5/23/2012 = 19,200

0.72

4.94

2.33

0.36

Depth, in meters

EXPLANATION

Depth-averaged velocity, in meters 

per second

Male pallid sturgeon location

Code 51 on May 21, 2012

Code 72 on May 23, 2012

A

B

C D

E F

Figure 4–21. Migration pathway, depth, and velocity of male pallid sturgeon codes 51 and 72 in the Yellowstone River, 

river mile 29.5, May 21 and 23, 2012. A, depth and location of codes 51 and 72; B, depth-averaged velocity and location 

of codes 51 and 72; C, depths used by and available to code 51, May 21, 2012; D, depths used by and available to code 

72, May 23, 2012; E, depth-averaged velocity used by and available to code 51, May 21, 2012; and F, depth-average 

velocity used by and available to code 72, May 23, 2012.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 175

Point observations along migration pathways provided 

estimates of pallid sturgeon migration rates, and hydraulic 

conditions (depth, velocity) used by and available to migrating individuals. Across individuals, upstream migration 

rates of telemetered pallid sturgeon along pathways averaged 0.25 meter per second (m/s) (range 0.10–0.47 m/s; 

mean=0.55 miles per hour [mi/h], range 0.22–1.05 mi/h; 

N=16 migration pathways). Pallid sturgeon used an average 

depth of 2.8 m while migrating, and the range of depths used 

varied from 1.3 m to 5.2 m (fig. 4–20). About 80 percent of the 

depth-use observations were located in 1.0–3.5 m. In comparison, available depths averaged 2.9 m, and ranged from 1.1 m 

to approximately 9.0 m. Pallid sturgeon used an average water 

column velocity of 1.16 m/s, but used water column velocities 

ranged from 0.15–2.61 m (fig. 4–20). Nearly 75 percent of 

the water velocities used by pallid sturgeon were 0.5–1.5 m/s. 

Water column velocities available to pallid sturgeon averaged 

1.13 m/s, with velocities of 0–2.7 m/s available along the 

migration points. Using mean column velocity, these results 

suggest that the average migrating pallid sturgeon swam 

upstream at a sustained rate of approximately 1.41 m/s to 

achieve a ground speed of 0.25 m/s against an average water 

velocity of 1.16 m/s; however, pallid sturgeon swim upstream 

along the bottom, and mean column velocity is not necessarily an accurate approximation of the velocities that sturgeon 

would be expected to experience. Mean column velocities 

are most likely substantially greater than current that pallid 

sturgeon swim against while migrating upstream.

In addition to quantifying depths and velocities used and 

available at migration points, detailed quantification of depths 

and velocities composing an 800-m reach of the Yellowstone 

River was done to characterize pathway conditions negotiated 

by two migrating pallid sturgeon (fig. 4–21). Within this reach, 

available depths varied from about 1.0 m to 5.0 m and water 

velocities from 0.5 m/s to 2.5 m/s. Pallid sturgeon code 51 and 

code 72 negotiated the reach using two different pathways. 

Code 51 entered the reach along the south bank of the main 

channel, maintained upstream migration along the south bank, 

and then crossed the channel to the north bank about mid-way 

through the reach. The migration trajectory for code 72 was 

initiated and maintained along the north bank of the river, 

followed by a cross-over to the south bank mid-way through 

the reach. Water depths used along both pathways differed 

slightly, but water velocities used were similar ranging from 

about 1.0 m/s to 1.7 m/s (fig. 4–21).

Spawning

Pallid sturgeon female code 30 was reproductivelyready in 2012 based on the reproductive assessment in April. 

Following a rapid upstream migration during June 6–9 and 

rapid downstream migration during June 9–10, code 30 was 

targeted for reproductive assessment to determine if code 

30 had spawned in the upstream reaches of the Yellowstone River (fig. 4–22). On June 12, code 30 was captured 

at RM 11.7 and ultrasound confirmed with gonadal biopsy 

indicated that code 30 had not spawned upstream as her body 

cavity remained filled with eggs. For the next several days, 

code 30 exhibited upstream (to at least RM 16.5) and downstream (near the Yellowstone River confluence) movements 

past aggregations of males. On June 19, code 30 was targeted 

for reproductive assessment within an aggregation of males at 

RM 6.7–7.1 (fig. 4–22). Code 30 and a male pallid sturgeon 

were captured in the same net with both individuals freely 

expressing sex products. Code 30 was weighed (16.0 kg), 

blood for hormone analysis was obtained, and it was quickly 

released. The presence of code 30 in the male aggregation, 

in conjunction with the observation that sex products were 

being released, provided evidence that code 30 had spawned 

in the capture area. Identical weights of code 30 on June 12 

and June 19 suggested that spawning was in the early stages 

as progressed spawning would be expected to decrease egg 

volume and reduce overall body weight. Numerous males 

were present in the spawning aggregation as evidenced by 

the detection of codes 11, 46, 49, 50, 51, 52, 68, 77, 70, and 

82. On June 20, code 30 and the male aggregation (detected 

codes 11, 46, 48, 50, 51, 52, 59, 68, 73, 77, 82) remained at 

the spawning location as of 12:15 p.m. Spawning activities 

were believed to be complete by mid- to late afternoon on 

June 20. Code 30 was slightly upstream from the spawn location and male aggregation at about 5:00 p.m. No other tagged 

sturgeon were present. At 9:30 a.m. on June 21, code 30 was 

about 1 mi upstream from the spawning location where she 

remained for several days prior to exiting the Yellowstone 

River. In addition, several of the males had exited the spawn 

area on June 21 and were found in the lower reaches of the 

Yellowstone River. Hormone analysis from the June 19 

collection indicated T=15.45 ng/mL and E2=nondetectable. 

River discharge averaged 21,250 ft3/s on June 19 and 20. 

From noon on June 19 to 5:00 p.m. on June 20, water temperature, based on hourly measurements from a data logger 

at river mile (RM) 2.5, averaged 20.3 oC (minimum=19.8 oC, 

maximum=21.0 oC).

A general description of the hydraulic conditions in the 

code 30 spawning reach is as follows. The spawning area 

was along the eastern edge of the channel in a swift-flowing 

trough (fig. 4–23). Point measurements in several areas of the 

spawning reach on June 20 indicated depths of 3.0–4.6 m, and 

a combination of substrates including sand, gravel, cobble, 

and large rock. River-ward from this trough and outside of 

the spawning area, sand was the primary substrate. A more 

detailed assessment and quantification of the spawning area 

may be completed in 2013.

Pallid sturgeon female code 35 was a second spawn candidate for 2012 following the initial reproductive assessment 

in April. Code 35 remained primarily in the lower parts of the 

Yellowstone River during early May, then exhibited repeated 

upstream (extending to RM 27.2) and downstream migrations during late May (fig. 4–22). At the initiation of another 

upstream migration in early June, code 35 was captured on 

June 4 for reproductive assessment. She remained full of eggs 

as determined from gonadal examination and weighed 28 kg. 
176 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

EXPLANATION

Location, in miles

0

10

20

30

40

50

60

70

0

10,000

20,000

30,000

40,000

5

10

15

20

25

30

River location 

River discharge

Water temperature

Location, in miles

0

10

20

30

40

50

60

70

0

10,000

20,000

30,000

40,000

5

10

15

20

25

30

Month

May June July Aug. 

Location, in miles

0

10

20

30

40

50

60

70

River discharge, in cubic feet per second

0

10,000

20,000

30,000

40,000

Water temperature, in degrees Celsius

5

10

15

20

25

30

Spawning

June 19, 2012

river mile 6.7–7.1

River discharge, in cubic feet per second River discharge, in cubic feet per second

Water temperature, in degrees Celsius Water temperature, in degrees Celsius

A. Code 30

B. Code 35

C. Code 36

Figure 4–22. Discharge, water temperature, and locations of gravid female pallid sturgeon in the Yellowstone River, May–

August 2012. A, code 30; B, code 35; and C, code 36.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 177

103°58’ 103°57’40” 103°57’20” 103°57’

47°53’45”

47°53’30”

47°53’15”

River miles from Yellowstone River

Cumulative Impact Study, 2001

(Applied Geomorphology, 2004)

Digital imagery from U.S. Department of 

Agriculture National Agriculture Imagery 

Program digital data, 2009

EXPLANATION

Yellowstone River mile marker—Number is 

distance upstream from the confluence 

with the Missouri River, in miles

7

6.4

6.5

6.6

6.7

6.8

6.9

7.1

7.2

7.3

0 125 250 METERS

0 500 1,000 FEET

7.3

Spawn

location

Figure 4–23. Spawn location of female pallid sturgeon code 30 in the lower Yellowstone River, June 19–20, 2012.
178 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Although her weight on June 4 was slightly less than recorded 

on April 23 (30 kg), code 35 had obviously not spawned. Hormone analysis from June 4 indicated an elevated concentration 

of T=82.07 ng/mL, but E2 had declined to a non-detectable 

concentration. Code 35 maintained the repeated upstream 

and downstream movement patterns through mid-June, and 

was detected at her maximum upstream location on June 19 

(RM 37.0). Code 35 was detected at about 5:00 p.m. on 

June 20 moving downstream towards the male aggregation 

at the code 30 spawn site; however, code 35 maintained the 

downstream migration past the male aggregation. Her downstream migration was maintained as code 35 was detected 

moving past the lower Yellowstone River logging station 

around 4:00 a.m. on June 21. After exiting the Yellowstone 

River, code 35 was not detected in the Yellowstone River 

again until June 24, but contacts were restricted to the lower 

part of the river. It was undetermined if code 35 spawned.

Pallid sturgeon female code 36 was the third spawn 

candidate for 2012 based on reproductive assessment in April. 

After exhibiting moderate upstream and downstream migrations through mid-May, code 36 was recaptured on May 15 

for reproductive assessment. She remained full of eggs and 

maintained a weight (18.0 kg) similar to the April 26 assessment (17.5 kg). Code 36 exhibited three additional upstream 

and downstream movements through late May (maximum 

extent to RM 37.2 on May 23), then exited the Yellowstone 

River after June 1 (fig. 4–22). Code 36 was not found in the 

Yellowstone River after June 1, but was located on June 12 in 

the Missouri River slightly downstream from the Yellowstone 

River confluence. Upon recapture, ultrasound examination 

determined that she had spawned. Code 36 weighed 16 kg, 

representing an 11.1 percent loss of body weight because of 

spawning. The location and timing of the code 36 spawning 

event were undetermined.

Collections of Free Embryos and Larvae

Intensive sampling for pallid sturgeon free embryos and 

larvae was initiated on June 18 (prior to the code 30 spawning event) and continued through June 26 in attempt to verify 

hatch and drift-entry of progeny from the code 30 spawning 

event. Sampling for the collection of progeny from code 30 

was based upon cumulative thermal units required for hatch. 

Calculations of dispersal assumed that free embryos entered 

the water column immediately upon hatch. Sampling was concentrated primarily below the code 30 spawning location, but 

sampling was also done at locations downstream to RM 2.5. A 

total of 184 samples was collected, partitioned among June 18 

(8 samples), June 19 (14 samples), June 20 (14 samples), June 

21 (12 samples), June 23 (28 samples), June 24 (28 samples), 

June 25 (56 samples) and June 26 (24 samples).

The sampling regime yielded 335 Acipenseriformes free 

embryos and larvae and 80 Acipenserifomes eggs and developing embryos. Genetic analysis differentiated all free embryos 

and larvae as paddlefish, shovelnose sturgeon, or pallid 

sturgeon (Heist and Eichelberger, 2013). Paddlefish composed 

79.4 percent (N=266) and shovelnose sturgeon 20.3 percent 

(N=68) of the free embryos and larvae sampled across dates. 

One naturally-spawned pallid sturgeon free embryo (0.3 percent of all individuals sampled) was genetically identified 

from a sample collected on June 25 immediately downstream 

from the code 30 female spawn site. Results from genetic 

parentage analysis indicated that the pallid sturgeon free 

embryo was not progeny from female code 30 or any of the 

males detected in the spawning aggregation. Rather, the pallid sturgeon free embryo was progeny from a known female 

(PIT 115557463A) spawned in the hatchery in 2008 and a 

known male (PIT 4440A7B73) spawned in the hatchery in 

2007 and 2009. Neither fish carried a transmitter, and as such, 

the location and timing of the spawn event that produced the 

wild free embryo were not known.

Summary

Migrations of pallid sturgeon into the Yellowstone River 

during 2012 were initiated by early April, increased through 

late May to a maximum of 90 percent of the telemetered 

population, and residency was maintained through mid- to late 

June. Thereafter, adult pallid sturgeon use of the Yellowstone 

River declined as fish returned downstream to the Upper Missouri River. The river entry and use patterns observed in 2012 

were similar to most other years of study (Fuller and Braaten, 

2013; Braaten and others, 2015), with the exception of 2011. 

In 2011, migrations into the Yellowstone River were initiated 

by early April but the maximum proportion of pallid sturgeon 

using the Yellowstone River (about 60 percent) was lower than 

other years (for example, more than 80 percent) as numerous 

pallid sturgeon migrated into and used the Missouri River 

below Fort Peck Dam.

Substantial variation in movements and migrations of 

telemetered pallid sturgeon was noted during 2012 as several 

individuals exhibited long-distance migrations, whereas others 

exhibited more restricted movements. Long-distance migrations within the Yellowstone River were depicted by male 

codes 42, 52, 69, 72 and 76 who exhibited migrations to Intake 

Dam. For most of these individuals, the persistent upstream 

migrations to Intake Dam generally coincided with periods of 

elevated discharge conditions. Pallid sturgeon arrived at Intake 

Dam from May 2–June 22. Seasonal maximum discharge 

happened on June 9. Under high discharge conditions during 

2011, eight telemetered pallid sturgeon were noted at Intake 

Dam with arrival dates as early as May 6 and residency at the 

dam persisting through June 16 (Braaten and others, 2015). 

Although no female pallid sturgeon were detected at Intake 

Dam in 2012, one gravid female was detected below Intake 

in 2007 (Fuller and others, 2008; Braaten and others, 2015). 

Code 72 was a repeat migrant to Intake as this individual also 

migrated to Intake Dam in 2011 (telemetry code 19 in 2011, 

arriving on June 9 versus June 13 in 2012) at a discharge of 

57,200 cubic feet per second (compared to 30,000 cubic feet 

per second in 2012).
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 179

Based on the finding that pallid sturgeon arrived at Intake 

Dam over a broad time interval and under a range of discharge 

conditions, the selected fish passage alternative for the reach 

affected by Intake Dam should similarly facilitate pallid 

sturgeon passage through a broad range of discharge conditions to accommodate early, mid-, and late pre-spawn migrants 

arriving at the Intake reach. Migration distances for all females 

exceeded 160 miles with the greatest female migration 

distance exhibited by code 30 (289 miles) who used both the 

Missouri River and Yellowstone River. None of the females 

monitored in 2012 migrated all the way to Intake Dam. Most

males (69 percent) exhibited migration distances that exceeded 

100 miles. Based on intensive telemetry relocation efforts in 

2007 and 2008, Fuller and Braaten (2013) report that total 

migration distance of pallid sturgeon within the Yellowstone 

River averaged 90 miles for males (range 14–267 miles) and 

171 miles for females (range 102–242 miles). 

As a fish passage alternative in the reach affected by 

Intake Dam, the proposed by-pass channel would be constructed on the south bank of the river with the downstream 

entrance of the by-pass channel joining the main stem river just 

downstream from the existing rock dam. One uncertainty associated with this alternative centers on pallid sturgeon approach 

pathways to the dam, and whether the south-bank entrance 

of the by-pass channel will be detected by migrating pallid 

sturgeon. Detailed assessments of approach pathways to Intake 

Dam in 2012 identified that male pallid sturgeon codes 52 and 

72 approached the dam closely along the outside-bend, south 

bank location or within the southern one-half of the river channel. These results contrast with findings from 2011 as approach 

pathways and relocations of pallid sturgeon were oriented 

towards the middle and northern part of the river channel along 

the inside bend (Braaten and others, 2015). Based on a limited 

number of observations, differences in approach pathways 

to Intake Dam between years may be related to differences 

in discharge between years and the subsequent influence of 

discharge on depths and the velocity field throughout the river 

channel. For example, during the high-discharge year of 2011, 

pallid sturgeon migrated primarily along the inside bends of the 

main channel where velocities were lower relative to riverward 

areas of the main channel. The north bank inside bend location 

downstream from Intake Dam in 2011 may have provided more 

suitable velocities for upstream migration than the mid- or outside bend channel locations as code 72 approached Intake Dam 

at 56,300 cubic feet per second (compared to 23,600–39,600 

cubic feet per second in 2012). Collectively, results from 2011 

and 2012 suggest that pallid sturgeon approach pathways 

to Intake Dam can vary depending on flow conditions. In 

addition, residency at Intake Dam during 2012 was brief as 

manual relocations complemented with detections from the 

Intake logging station indicated that pallid sturgeon remained 

directly downstream from the dam for only 1–2 days. Within 

the short time frames of assessing codes 52 and 72, there was 

little evidence of extensive lateral search behavior exhibited by 

the pallid sturgeon. Pallid sturgeon during elevated discharge 

conditions of 2011 exhibited substantial variability in residence 

time below Intake Dam as some individuals were present for 

one day whereas other individuals remained for several days 

(Braaten and others, 2015).

Assessments of migration pathways identified pallid sturgeon swimming routes and associated habitat elements used 

by migrating individuals within the heterogeneous channel of 

the Yellowstone River. Under the moderate flow conditions of 

2012, pallid sturgeon migrated primarily in the main channel 

along the inside bends; however, pallid sturgeon also migrated 

through outside bend and mid-channel habitats. These results 

contrast the small dataset obtained in 2011 as pallid sturgeon 

migrated almost exclusively along the inside bend under 

elevated discharge conditions of 2011. As noted earlier, migration pathways may differ under different discharge because of 

the effects of discharge on velocity and depth throughout the 

river channel.

Prior to 2011 and 2012, little information was available 

on pallid sturgeon use of and migrations through side channels 

as related to the potential by-pass channel alternative for the 

reach affected by Intake Dam. The limited migration-pathway 

dataset from 2011 identified that pallid sturgeon did use side 

channels (Braaten and others, 2015) as successful upstream 

passage was documented through short side channels (for 

example, 0.25–1.25 miles long) located on the inside bends of 

the main channel. Pallid sturgeon also were located in longer 

side channels during 2011, but upstream passage was not 

documented as individuals were either sedentary or moving 

downstream through the channel. In 2012, pallid sturgeon 

migrated primarily in the main channel as multiple side channels (for example, 0.5–2.0 miles long) within the migration 

corridor were infrequently used during upstream migration; 

however, some use and successful passage through side channels 0.25–1.6 miles long were documented for a few individuals. In addition, use and upstream progression was happening 

in a long side channel (1.7 miles long) by female code 30 prior 

to this individual turning around and moving downstream. 

Based on these results, we can conclude that pallid sturgeon 

will use side channels during upstream migrations; however, 

use may be infrequent. In addition, results from 2011 and 2012 

depict inconsistencies in side channel use among individuals. 

For example, in early June 2011, two pallid sturgeon were 

tracked under similar discharge conditions through an inside 

bend complex that contained a side channel. One pallid sturgeon entered and successfully negotiated the side channel as 

part of the migration pathway. The other individual maintained 

a migration pathway exclusively in the main channel. Differences in side channel use between individuals under similar 

discharge conditions were observed in 2012 as presented for 

codes 36 and 37, and codes 36 and 69. Additional variation in 

migration pathways was noted for codes 51 and 72 in the main 

channel of the Yellowstone River.

In most cases, upstream migrations in the main channel 

and split channel configurations were nearly continuous. Observation of radio-tracked sturgeon in the Yellowstone River using 

DIDSON® show that pallid sturgeon typically swim close to the 

bottom. Pallid sturgeon are highly adapted to swift currents in 
180 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

sand-bottomed rivers, and are likely efficient at exploiting flow 

fields and bedforms to reduce energy expenditure during migration. The velocity conditions that pallid sturgeon experience 

near the bottom during migration are not known. Based upon 

variables that can be readily measured, pallid sturgeon used 

migration pathways that resulted in an average ground speed of 

about 0.25 meter per second against an average mean-column 

velocity of 1.16 meters per second. Braaten and others (2015) 

similarly found that migrating pallid sturgeon exhibited ground 

speeds of about 0.20–0.25 meters per second. Better estimates 

of the conditions near the bottom where pallid sturgeon forage, 

migrate, and spawn are needed to evaluate habitat use, availability selection, and suitability for adults.

Spawning in the Yellowstone River was documented for 

two females (code 30 and a non-telemetered parent of the free 

embryo) and spawning by a third female (code 36) in either 

the Yellowstone River or Missouri River was confirmed in 

2012. Although the exact date(s) of spawning events was not 

determined for all females, results suggest slight variation in 

the timing of spawning events for pallid sturgeon as female 

code 36 spawned prior to June 12 and code 30 spawned on 

June 19–20. The spawning event that produced the pallid 

sturgeon free embryo collected in 2012 likely happened on 

a date similar to the code 30 spawning event given the early 

developmental stage of the free embryo. Under a discharge 

regime similar to 2012, Fuller and others (2008) suggested 

that spawning in 2007 likely happened between June 13–16 

as a spawn-candidate female and multiple males formed an 

aggregation during these dates. Under elevated discharges in 

the Yellowstone River during 2011, spawning had not happened prior to June 21 through the last date a telemetered 

spawn-candidate female was found in the Yellowstone River 

(Braaten and others, 2015). The collection of code 30 on June 

19 isolated not only the specific date of the spawning event 

in 2012, but also identified the specific location of a spawning event in the Yellowstone River (river mile 6.7–7.1). Fuller 

and others (2008) suggested that this reach of the Yellowstone 

River was a spawning site in 2007 as the spawn-candidate 

female and multiple males formed an aggregation near river 

mile 7.5 of the Yellowstone River. Close proximity of the 2007 

aggregation site and 2012 known spawning site suggests that 

this reach may be a repeat spawn location under discharge 

conditions characteristic of 2007 and 2012. Although this has 

been confirmed in the lower reaches of the Yellowstone River, 

spawning also may happen in the middle reaches of the Yellowstone River (Fuller and others, 2008).

Collection of the wild-produced pallid sturgeon free 

embryo in 2012 indicates that the reproductive process from 

fertilization to drift-entry of free embryos was successful 

under the hydrological and thermal regimes characteristic of 

the Yellowstone River in 2012. Only one other study in the 

Missouri River has verified survival and hatch of pallid sturgeon embryos; a genetically confirmed wild-produced pallid 

sturgeon free embryo was also sampled in the Missouri River 

below Fort Peck Dam during 2011 (DeLonay and others, 

2014). 

References Cited

Braaten, P.J., Fuller, D.B., Holte, L.D., Lott, R.D., Viste, William, Brandt, T.F., and Legare, R.G., 2008, Drift dynamics of larval pallid sturgeon and shovelnose sturgeon in a 

natural side channel of the upper Missouri River, Montana: North American Journal of Fisheries Management, 

v. 28, no. 3, p. 808–826. [Also available at http://dx.doi.

org/10.1577/M06-285.1.]

Braaten, P.J., Fuller, D.B., Lott, R.D., Ruggles, M.P., and 

Holm, R.J., 2010, Spatial distribution of drifting pallid sturgeon larvae in the Missouri River inferred from 

two net designs and multiple sampling locations: North 

American Journal of Fisheries Management, v. 30, no. 4, 

p. 1062–1074. [Also available at http://dx.doi.org/10.1577/

M09-149.1.]

Braaten, P.J., Fuller, D.B., Lott, R.D., Ruggles, M.P., Brandt, 

T.F., Legare, R.G, and Holm, R.J., 2012, An experimental 

test and models of drift and dispersal processes of pallid 

sturgeon (Scaphirhynchus albus) free embryos in the Missouri River: Environmental Biology of Fishes, v. 93, no. 3, 

p. 377–392. [Also available at http://dx.doi.org/10.1007/

s10641-011-9925-9.]

Braaten, P.J., Elliott, C.M., Rhoten, J.C., Fuller, D.B., and 

McElroy, B.J., 2015, Migrations and swimming capabilities 

of endangered pallid sturgeon (Scaphirhynchus albus) to 

guide passage designs in the fragmented Yellowstone River: 

Restoration Ecology, v. 23, no. 2, p. 186–195. [Also available at http://dx.doi.org/10.1111/rec.12161].

DeLonay, A.J., Jacobson, R.B., Annis, M.L., Braaten, P.J., 

Chojnacki, K.A., Elliott, C.M., Fuller, D.B., Haas, J.D., 

Haddix, T.M., McElroy, B.J., Mestl, G.E., Papoulias, 

D.M., Rhoten, J.C., and Wildhaber, M.L., 2014, Ecological 

requirements for pallid sturgeon reproduction and recruitment in the Missouri River—Annual report 2011: U.S. Geological Survey Open-File Report 2014–1106, 96 p. [Also 

available at http://dx.doi.org/10.3133/ofr20141106.]

Fuller, D.B., and Braaten, P.J., 2013, Fort Peck flow modification biological data collection plan compendium—Summary of 2001–2009 activities: Report submitted to the 

U.S. Army Corps of Engineers, Montana Fish, Wildlife and 

Parks, 122 p. 

Fuller, D.B., Jaeger, M.E., and Webb, Molly, 2008, Spawning 

and associated movement patterns of pallid sturgeon in the 

lower Yellowstone River: Western Area Power Administration, Upper Basin Pallid Sturgeon Work Group, U.S. Army 

Corps of Engineers, Montana Fish, Wildlife and Parks, 22 p.

Heist, E.J., and Eichelberger, J., 2013, 2012 genetic analysis of 

Missouri River sturgeon larvae: Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University 

Carbondale, 27 p.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 181

Kynard, B., Parker, E., Pugh, D., and Parker, T., 2007, Use of 

laboratory studies to develop a dispersal model for Missouri 

River pallid sturgeon early life intervals: Journal of Applied 

Ichthyology, v. 23, no. 4, p. 365–374. [Also available at 

http://dx.doi.org/10.1111/j.1439-0426.2007.00908.x.]

U.S. Fish and Wildlife Service, 2007, Pallid sturgeon (Scaphirhynchus albus) 5-year review—Summary and evaluation: 

Billings, Mont., U.S. Fish and Wildlife Service, 120 p.

U.S. Army Corps of Engineers, 2012, Intake diversion dam 

modification, lower Yellowstone Project, Montana, Bypass 

channel 30% design documentation report: U.S. Army 

Corps of Engineers.

U.S. Bureau of Reclamation, and U.S. Army Corp of Engineers, 2014, Intake diversion dam modification lower Yellowstone Project, Montana: Draft supplement to the 2010 

final environmental assessment: U.S. Bureau of Reclamation, Billings, Mont., and U.S. Army Corps of Engineers, 

Omaha, Nebr., 144 p.

U.S. Fish and Wildlife Service, 1993, Recovery plan for the 

pallid sturgeon (Scaphirhynchus albus): Denver, Colo., 

U.S. Fish and Wildlife Service, Region 6, 55 p.

U.S. Fish and Wildlife Service, 2000, Biological opinion on 

the operation of the Missouri River main stem reservoir 

system, operation and maintenance of the Missouri River 

bank stabilization and navigation project, and operation of 

the Kansas River reservoir system: U.S. Fish and Wildlife 

Service, 308 p.

U.S. Fish and Wildlife Service, 2003, Amendment to the 2000 

biological opinion on the operation of the Missouri River 

main stem reservoir system, operation and maintenance 

of the Missouri River bank stabilization and navigation 

project, and operation of the Kansas River reservoir system: 

U.S. Fish and Wildlife Service, 308 p. [Also available at 

http://www.nwd-mr.usace.army.mil/mmanual/FinalBO2003.

pdf.]
182 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Appendix 5. Adult Pallid Sturgeon Blood Chemistry

second time to consider the length of time the sturgeon spent 

in captivity to evaluate changes in blood chemistry for male 

and female, nonreproductive and reproductive pallid sturgeon (table 5–2). In this analysis four categories were used to 

describe the length of captivity: (1) sturgeon that were held 

0–7 days (recent), (2) sturgeon there were held 8–30 days 

(brief), (3) sturgeon that were held >30 days (prolonged), 

and (4) sturgeon that were held all their lives (life-captive). 

Analysis of variance using least-squares means for pairwise 

comparisons (p<0.05) was used to test for differences.

Results

Cholesterol is essential for cell health and development 

as well as for production of steroids. Cholesterol was higher in 

reproductively ready fish than in nonreproductive fish. Reproductive males had more cholesterol than reproductive females, 

and captive females had slightly higher cholesterol than wild 

females (fig. 5–1). Overall, cholesterol concentrations tended to 

be slightly higher in pallid sturgeon compared to values reported 

for shovelnose sturgeon (Scaphirhynchus platorynchus) (Hunn 

and Christenson, 1977). Sturgeon in reproductive condition with 

late-stage, vitellogenic oocytes (stages IV and V) are reported to 

have higher cholesterol than those in nonreproductive condition 

or post-spawn (Barannikova and others, 2008).

Creatinine is a product of the metabolism of amino acids 

primarily in white muscles. Although abnormal concentrations 

have been linked to adverse effects on the kidney in mammals, 

not much is known about this relation in fish (Thrall and others, 

2012). Concentrations of creatinine in the blood were generally 

higher in males than females. Captive sturgeon showed higher 

concentrations of creatinine compared to their wild counterparts (table 5–1). Nonreproductive fish of either sex, wild or 

captive, had higher creatinine concentrations than reproductive 

fish. The normal range for creatinine in teleosts is from 0.5 to 

2.0 milligrams per deciliter (mg/dL) (Thrall and others, 2012), 

similar to what has been reported for several sturgeon species 

(Asadi and others, 2006; Shi and others, 2006). Except for one 

prolonged-captive male pallid with a creatinine concentration 

of 5.8 mg/dL, all pallid sturgeon sampled were within the range 

of less than or equal to (< ) 0.03–1.0).

Elevated glucose in the blood can be an indicator of 

stress, whereas low glucose can indicate starvation or liver 

damage. Glucose also may be normally mobilized during periods of strenuous activity such as migration. Male glucose concentrations were slightly higher than female concentrations. 

Reproductive males and nonreproductive females had higher 

glucose concentrations than reproductive females (table 5–1, 

fig. 5–2). Pallid sturgeon glucose concentrations were lower 

than those measured in shovelnose sturgeon, but were within 

the range seen in other sturgeon species (Sepúlveda and others, 2012). The same sex-specific differences were observed in 

shovelnose sturgeon (Sepúlveda and others, 2012).

Background

Blood diagnostic tests on fish are increasingly being used 

to assess general metabolic and reproductive health (Folmar, 

1993; Shahsavani and others, 2010; Di Marco and others, 

2011); accordingly, when the normal condition is known, such 

blood biomarkers may be used to identify those fish adversely 

affected by chemical and nonchemical stressors; however, 

many factors influence blood chemistry including sex, reproductive stage, nutrition, and temperature.

Scope and Objectives

The objective of this study was twofold: (1) to build 

datasets that can be useful in explaining the biochemical and 

physiological condition of adult pallid sturgeon (Scaphirhynchus albus), and (2) to explore sensitivity of pallid sturgeon 

blood chemistry to environmental conditions.

Methods

We sampled a blood plasma from a total of 194 pallid 

sturgeon of known sex and reproductive stage between 2005 

and 2012. The sturgeon sampled included wild-captured 

adults from the Lower Missouri River, which may have been 

released immediately after capture, or transported and held 

for an indeterminate time at hatcheries as potential propagation broodstock. Adult pallid sturgeon from captive, hatchery 

populations were also sampled. Plasma was subjected to a 

series of diagnostic tests for metabolic condition. Results were 

examined for differences by sex, reproductive status, time 

elapsed since capture, and time in captivity. Male reproductive 

status was categorized as reproductive or nonreproductive. 

Female reproductive status was categorized as reproductive, 

nonreproductive, or post-spawn.

For all samples, blood (5–10 milliliters [mL]) was collected from the caudal vein, transferred into heparinized vials, 

and held on wet ice until centrifuged. Blood was centrifuged 

at 3,500 rotations per minute (rpm) for 10 minutes, and then 

plasma was removed by transfer pipette to two or three cryovials. Plasma was kept frozen until use at -80 degrees Celsius 

(oC). Total cholesterol, creatinine, glucose, lactate, lipase, total 

triglycerides, and total protein were measured. Lactate was 

measured only in blood samples centrifuged within 15 minutes 

of collection. Measurements were made on blood plasma with 

a Vitros DTII (Johnson & Johnson, Rochester, New York).

Data were first examined to compare the differences 

between sturgeon captured from the wild and held captive for 

less than (<) 1 month (wild) and sturgeon held in a hatchery 

environment for greater than (>) 1 month (prolonged) (table 

5–1). Relations between groups were studied to determine 

the effects of capture, transport, and acclimation to hatchery 

conditions on pallid sturgeon. Data were then examined a 
Table 5–1. Plasma chemistry for pallid sturgeon according to sex, reproductive state, and whether they were captured from the wild and held than 1 month or held captive in the hatchery environment (more than 1 month).[Values are reported as means±standard deviation with range in parenthesis. ±, plus or minus; ≤, less than or equal to; ≥, greater than or equal to; mg/dL, milligrams per demmol/ L, millimole per liter; g/dL, gram per decilite]

Sex Reproductive status Captivity Number Cholesterol (mg/dL) Creatinine (mg/dL) Glucose (mg/dL) Lipase (U/L) Lactate (mmol/L) Total pro

(g/dL

Female Nonreproductive Prolonged 18 161±96 0.30±0.40 53±18 12±10 11.7±1.6 4.0±1

(25–336) (≤0.03–1.0) (31–103) (≤5–37) (0.3–5.2) (1.0–6

Wild 26 107±64 0.17±0.25 54±28 5±2 4.4±3.3 2.6±1

(25–325) (≤0.03–1.00) (27–139) (≤5–11) (0–12.0) (1.0–5

Reproductive Prolonged 14 166±83 0.10±0.13 40±8 ≤5±0 0.5±0.8 2.9±1

(55–322) (≤0.03–0.40) (27–51) (≤5) (0–2.3) (1.0–4

Wild 12 120±71 0.09±0.15 45±13 8±10 2.9±2.0 2.9±0

(25–274) (≤0.03–0.50) (32–77) (≤5–38) (0–5.5) (2.2–3

Post-spawn Prolonged 5 67±24 0.17±0.08 38±7 8±4 1.5 ±0.5 4.2 ±0

(55–110) (≤0.03–0.20) (32–47) (≤5–13) (1.1–2.3) (3.8–4

Wild 9 154±75 ≤0.03±0 64±22 9±11 6.6±1.9 2.7±1

(55–325) (≤0.03) (28–97) (≤5–38) (2.5–9.2) (1.0–4

Male Nonreproductive Prolonged 37 132±46 0.43±0.30 56±13 13±8 0.6±0.9 4.3±1

(59–284) (≤0.03–1.00) (31–78) (≤5–33) (0–1.6) (2.4–9

Wild 28 122±48 0.12±0.22 63±25 6±3 5.5±4.2 2.6±1

(55–285) (≤0.03–0.80) (36–128) (≤5–18) (0–12) (1.0–5

Reproductive Prolonged 5 198±66 1.40±2.47 75±34 ≤5±0 2.0±1.7 3.7±0

(143–303) (≤0.03–5.80) (36–122) (≤5) (0.8–5) (2.7–4

Wild 11 256±88 0.04±0.05 62±29 6±4 3.2±3.9 2.9±1

(71–336) (≤0.03–0.20) (40–125) (≤5–18) (0.7–11.1) (1.0–4

1Only seven samples for lactate.2The upper limit of quantitation for triglygerides was 800 mg/dL.
Table 5–2. Blood chemistry of Missouri River pallid sturgeon. [Sturgeon were grouped according to sex, reproductive stage, and time in captivity. Blood was collected from recently captured fish (=Recent) within 0–7 days after capture while they were held temporarily in a hatchery awaiting spawning. Blood was collected from fish held for a short period (=Briefly) or long period (=Prolonged) between 8–31 month, respectively. Blood collected from fish maintained in captivity all or most of their life (=Life-captive). Results are means±standard deviation. Minimum and maxim

thesis. Superscripts within each sex and reproductive status combination for a biomarker indicate significant differences at p<0.05; --, no data; ±, plus or minus; mg/dL, milliunits per liter; mmol/ L, millimole per liter; g/dL, gram per decilite] Sex Reproductive status Captivity Number Cholesterol (mg/dL) Creatinine (mg/dL) Glucose (mg/dL) Lipase (U/L) Lactate (mmol/L) Total p

(g/

Female Nonreproductive Recent 24 106±65 0.18±0.26a 56±29 5±2a 4.7±3.2a 2.6±

(25–325) (0.03–1.00) (27–139) (5–11) (0.0–12.0) (1.0–

Briefly 2 122±58 ≤0.03±0.00a 43±3 5±0a 0.7±0.1b 1.7±

(81–163) (≤0.03) (41–45) -5 (0.60.8) (1.0–

Prolonged 7 222±130 ≤0.03±0.00a 48±25 5±0a 1.7±1.6b 3.1±

(25–336) (≤0.03) (31–103) -5 (0.0–5.2) (1.0–

Life-captive 11 122±36 0.47±0.37b 56±12 16±11b -- 4.5±

(81–201) (≤0.03–1.00) (31–72) (5–37) -- (2.9–

Reproductive Recent 8 93±55 0.12±0.18 44±15 9±12 4.1±1.2a 3.0±

(25–159) (≤0.03–0.50) (32–77) (5–38) (2.6–5.5) (2.2–

Briefly 8 165±63 ≤0.03±0.00a 45±7 5±0 0.4±0.5b 2.4±

(112–274) (≤0.03) (39–59) -5 (0.0–1.4) (2.1–

Prolonged 7 200±90 ≤0.03±0.00a 43±7 5±0 0.5±0.8b 3.1±

(56–322) (≤0.03) (34–51) -5 (0.0–2.1) (2.4–

Life-captive 7 131±65 0.17±0.15b 37±8 5±0 0.5±0.9b 2.7±

(55–216) (≤0.03–0.40) (27–50) -5 (0.0–2.3) (1.0–

Post-spawn Recent 9 154±75a ≤0.03±0.00a 64±22a 9±11 6.6±1.9a 2.7±

(55–325) (≤0.03) (28–97) (5–38) (2.5–9.2) (1.0–

Life-captive 5 67±24b 0.17±0.08b 38±7b 8±4 1.5±0.5b 4.2±

(55–110) (≤0.03–0.20) (32–47) (5–13) (1.1–2.3) (3.8–
Sex Reproductive status Captivity Number Cholesterol (mg/dL) Creatinine (mg/dL) Glucose (mg/dL) Lipase (U/L) Lactate (mmol/L) Total 

(g/

Male Non-Reproductive Recent 25 120±44 0.12±0.23a 65±25 6±3a 6.2±4.0a 2.7±

(82–285) (≤0.03–0.80) (36–128) (5–18) (0.0–12.0) (1.0

Briefly 5 126±69 0.06±0.08a 43±6 5±0a 0.5±0.3b 1.6±

(55–222) (≤0.03–0.20) (37–50) -5 (0.0–0.7) (1.0

Life-captive 37 132±46 0.43±0.30b 56±13 13±8b 0.6±0.9b 4.3±

(59–284) (≤0.03–1.00) (31–78) (5–33) (0.0–1.6) (2.4

Reproductive Recent 11 256±88 0.04±0.05a 61±29 6±4 3.2±3.9 2.8

(71–336) (≤0.03–0.20) (40–125) (5–18) (0.7–11.1) (1.0

Prolonged 1 303 ≤0.03 48 5 5 3

-303 (≤0.03) -48 -5 -5 -3

Life-captive 4 172±34 1.75±2.70 82±35 5±0 1.2±0.3 3.6

(143–212) (0.20–5.80) (36–122) -5 (0.8–1.5) (2.7

Table 5–2. Blood chemistry of Missouri River pallid sturgeon.—Continued[Sturgeon were grouped according to sex, reproductive stage, and time in captivity. Blood was collected from recently captured fish (=Recent) within 0–7 days after capture while they were held temporarily in a hatchery awaiting spawning. Blood was collected from fish held for a short period (=Briefly) or long period (=Prolonged) between 8–31 month, respectively. Blood collected from fish maintained in captivity all or most of their life (=Life-captive). Results are means±standard deviation. Minimum and maxim

thesis. Superscripts within a sex-stage category for a biomarker indicate significant differences at p<0.05; --, no data; ±, plus or minus; mg/dL, milligrams per deciliter; U/Lmillimole per liter; g/dL, gram per decilite]
186 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

0

50

100

150

200

250

300

< 0.0001

0.0002

0.0034

133

45

30

30

15

47

37

Nonreproductive

Reproductive

Reproductive female

Reproductive male

Wild female

Captive female

Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

Cholesterol, in milligrams per liter, mean plus one standard error

Figure 5–1. Mean plasma cholesterol concentrations in pallid sturgeon. Glucose, in milligrams per liter, mean plus one standard error

Reproductive

female

Nonreproductive

female

Reproductive male

Male

Female

0

20

40

60

80

0.0004

44

0.0326

30

67

88

84

0.0027

30 Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

Figure 5–2. Mean plasma glucose concentrations in pallid sturgeon.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 187

Elevated lactate is a secondary stress response in most 

fish, although this response may be reduced in sturgeons 

(Baker and others, 2005). Lactate also increases in response 

to hypoxia (Heath, 1995). Results show that plasma lactate 

concentrations are higher in males than females. Nonreproductive fish had generally higher concentrations of lactate 

than reproductive fish, and wild fish had higher lactate concentrations than captive fish (fig. 5–3). Previous studies with 

other species of sturgeon have measured differences in lactate 

concentrations between sturgeon at rest (1 millimole per liter 

[mmol/L]) and sturgeon present with a stressor (>4 mmol/L) 

(Beyea and others, 2005; Zuccarelli and others, 2008). 

Results from these studies indicate a comparable lactate stress 

response in wild pallid sturgeon in comparison to their captive counterparts.

Lipase is a fat-digesting enzyme. Adult pallid sturgeon 

typically have low plasma lipase concentrations because they 

are primarily piscivorous. Lipase concentrations were highest 

in nonreproductive captive pallid sturgeon when compared 

to either reproductive captive or nonreproductive wild pallid 

sturgeon (fig. 5–4). Comparative data from literature are not 

available; however, results suggest that diets of prolongedcaptive pallid sturgeon may have abnormally high lipids.

The total protein measurement reflects the amount of 

albumin and globulin in blood. Albumin contributes to cell 

health and globulin to proper function of the immune system. 

Albumin and globulin are important in the endocrine system, 

especially related to reproduction. Males were slightly higher 

in blood total protein than females. Captive fish had higher 

protein than wild fish, and captive, nonreproductive fish had 

higher concentrations than captive, reproductive fish (fig. 5–5). 

Total protein in shovelnose sturgeon was only slightly higher 

than that measured in pallid sturgeon (Sepúlveda and others, 

2012).

Stored triglycerides provide the energy source for activities such as swimming, reproduction, and detoxification. 

Triglyceride concentrations were higher in males compared to 

females and higher in wild pallid sturgeon compared to captive pallid sturgeon (fig. 5–6). Total triglyceride concentrations 

in pallid sturgeon were slightly lower than those reported for 

white sturgeon (Fynn-Aikins and others, 1992).

In a second analysis, sturgeon that had been in captivity all their lives (life-captive) regardless of sex or stage, 

had higher creatinine values than sturgeon that were held in 

captivity 0–7 days (recent), 8–30 days (brief), or >30 days 

(prolonged). Not all categories had sufficient fish for which 

to complete a robust analysis; however, apart from lactate, 

there were few differences in blood biomarker concentrations 

between recent-captive fish and briefly- and prolonged-captive 

fish. Conversely, nearly all biomarkers for these fish differed 

from those of the pallid sturgeon that had spent their entire 

lives in captivity.

Lactate, in milligrams per liter, mean plus one standard error

Nonreproductive

Reproductive

Wild

Captive

Male

Female

0

0.0384

0.0243

< 0.0001

78

44

77

46

35

96

1

2

3

4

5

30 Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

Figure 5–3. Mean plasma lactate concentrations in pallid sturgeon.
188 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012 Lipase, in units per liter, mean plus one standard error

Nonreproductive captive

Nonreproductive wild

Nonreproductive

Reproductive captive

Reproductive

Captive

Wild

0

2

4

6

8

10

12

14

16

0.0269

< 0.0001

0.0001

 < 0.0001

30 Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

55

74

19 54

77 42

109

Figure 5–4. Mean plasma lipase concentrations in pallid sturgeon.

0

1

2

3

4

5

6

< 0.0001

0.0339

19

57

84

88

0.0195

74

< 0.0001

82

106

30 Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

Total protein, in grams per liter, mean plus one standard error

Nonreproductive captive

Reproductive captive

Nonreproductive wild

Female

Male

Wild

Captive

Figure 5–5. Mean plasma total protein concentrations in pallid sturgeon.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 189

Summary

When comparative data for other sturgeon species were 

available, sex- and stage-specific trends in pallid sturgeon 

blood chemistry biomarkers were similar. Differences between 

shovelnose sturgeon and pallid sturgeon values for some 

blood chemistry parameters may reflect subtle differences in 

physiology or ecology. Conversely, differences in environmental conditions under which the fish lived could account for 

the disparate values. Insights into the ecological differences 

between these two congenerics may be obtained by comparing 

measured blood chemistry of the two species under the same 

controlled conditions.

Captive and wild pallid sturgeon differed for all biomarkers except glucose. Not surprisingly, the fishes’ physiology 

had changed while in captivity, highlighting the differences 

between the hatchery and the Missouri River for nutrition, 

water temperature, and a variety of other environmental variables. Concentrations of creatinine and lactate were elevated 

in wild fish, which suggests that capture, transport, and acclimation to the hatchery environment is stressful to pallid sturgeon. It is unknown whether that stress has consequences for 

the future health of the fish. Analysis of the data from fish held 

in captivity through time indicate that blood concentrations of 

these biomarkers decline by 8–30 days in captivity, suggesting 

that acclimation happens during several weeks.

 Extensive monitoring programs target and capture pallid 

sturgeon in the Missouri River to assess movement and population demographics (Welker and Drobish, 2009). Intensive 

coordinated capture efforts are done annually to collect and 

transport potential broodstock to hatcheries across the basin 

(U.S. Fish and Wildlife Service, 2008a, b). Broodstock may 

be held in unnatural conditions for an extended period of time 

before artificial induction of spawning and eventual release. At 

present (2012), little information exists to assess the physiological effect of capture and transport on juvenile and adult 

pallid sturgeon under field conditions. Without adequate 

baseline data, biologists have few tools at their disposal to 

assess the short-term physiological status or long-term condition of captive pallid sturgeon juveniles or adults (Barton and 

others, 2000). Without insight into the physiological status 

of broodstock, evaluation of induction and spawning success 

may be difficult to interpret (Bayunova and others, 2002). 

Development of hematological profiles of pallid sturgeon may 

be useful in assessing stress or changes in physiological condition that accompany propagation activities or environmental 

stresses such as capture, starvation, migration, or spawning 

(for example, Shahsavani and others, 2010; and Di Marco and 

others, 2011).

References Cited

Asadi, F., Masoudifard, M., Vajhi, A., Lee, K., Pourkabir, M., 

and Khazraeinia, P., 2006, Serum biochemical parameters 

of Acipenser persicus: Fish Physiology and Biochemistry, v. 32, no. 1, p. 43–47. [Also available at http://dx.doi.

org/10.1007/s10695-005-5738-0.]

Baker, D.W., Wood, A.M., Litvak, M.K., and Kieffer, J.D., 

2005, Haematology of juvenile Acipenser oxyrinchus

and Acipenser brevirostrum at rest and following forced 

activity: Journal of Fish Biology, v. 66, no. 1, p. 208–221. 

[Also available at http://dx.doi.org/10.1111/j.0022-

1112.2005.00595.x.]

0

100

200

300

400

500

600

0.0482

< 0.0001

88

84

82

106 30 Number on bar indicates number of fish

Whiskers indicated one standard error

Analysis of variance using least-squares means for pairwise 

 comparisons was used to test for differences. Horizontal 

 lines above bars indicate means that were significantly 

 different at p < 0.05. P-values are noted above bars for 

 results of post-hoc comparisons. 

EXPLANATION

Triglycerides, in milligrams per deciliter, 

mean plus one standard error

Female

Male

Wild

Captive

Figure 5–6. Mean plasma total triglyceride concentrations in pallid sturgeon.
190 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Barannikova, Irina, Bayunova, Liubov, Semenkova, Tatiana, 

and Trenkler, Igor, 2008, Physiological changes in Russian 

sturgeon (Acipenser gueldenstaedtii) after long-term holding and final maturation: Cybium, v. 32, no. 2, p. 321–322.

Barton, B.A., Bollig, Herbert, Hauskins, B.L., and Jansen, 

C.R., 2000, Juvenile pallid (Scaphirhynchus albus) and 

hybrid pallid x shovelnose (S. albus x platorynchus) sturgeons exhibit low physiological responses to acute handling 

and severe confinement: Comparative Biochemistry and 

Physiology Part A, v. 126, p. 125–134.

Bayunova, L., Barannikova, I., and Semenkova, T., 2002, 

Sturgeon stress reactions in aquaculture: Journal of Applied 

Ichthyology, v. 18, no. 4–6, p. 397–404. [Also available at 

http://dx.doi.org/10.1046/j.1439-0426.2002.00410.x.]

Beyea, M.M., Benfey, T.J., and Kieffer, J.D., 2005, Hematology and stress physiology of juvenile diploid and triploid 

shortnose sturgeon (Acipenser brevirostrum): Fish Physiology and Biochemistry, v. 31, no. 4, p. 303–313. [Also available at http://dx.doi.org/10.1007/s10695-005-1552-y.]

Di Marco, P., Priori, A., Finoia, M.G., Petochi, T., Longobardi, 

A., Donadelli, V., and Marino, G., 2011, Assessment of 

blood chemistry reference values for cultured sturgeon 

hybrids (Acipenser naccarii female x Acipenser baerii

male): Journal of Applied Ichthyology, v. 27, no. 2, p. 584–

590. [Also available at http://dx.doi.org/10.1111/j.1439-

0426.2011.01713.x.]

Folmar, L.C., 1993, Effects of chemical contaminants on blood 

chemistry of teleost fish—A bibliography and synopsis of 

selected effects: Environmental Toxicology and Chemistry, 

v. 12, no. 2, p. 337–375. [Also available at http://dx.doi.

org/10.1002/etc.5620120216.]

Fynn-Aikins, Kofi, Hung, S.S.O., Liu, Wei, and Li, Hongbin, 

1992, Growth, lipogenesis and liver composition of juvenile 

white sturgeon fed different levels of D-glucose: Aquaculture, v. 105, no. 1, p. 61–72. [Also available at http://dx.doi.

org/10.1016/0044-8486(92)90162-E.]

Heath, A.G., 1995, Water pollution and fish physiology (2d 

ed.): Boca Raton, Fla., CRC Press, Inc., 384 p.

Hunn, J.B., and Christenson, L.M., 1977, Chemical composition of blood and bile of the shovelnose sturgeon: 

The Progressive Fish-Culturist, v. 39, no. 2, p. 59–61. 

[Also available at http://dx.doi.org/10.1577/1548-

8659(1977)39[59:CCOBAB]2.0.CO;2.]

Sepúlveda, M.S., Sutton, T.M., Patrick, H.K., and Amberg, 

J.J., 2012, Blood chemistry values for shovelnose and lake 

sturgeon: Journal of Aquatic Animal Health, v. 24, no. 3, 

p. 135–140. [Also available at http://dx.doi.org/10.1080/089

97659.2012.675927.]

Shahsavani, Davar, Kazerani, H.R., Kaveh, Samira, and Gholipir-Kanani, Hosna, 2010, Determination of some normal 

serum parameters in starry sturgeon (Acipenser stellatus

Pallas, 1771) during spring season: Comparative Clinical 

Pathology, v. 19, no. 1, p. 57–61. [Also available at http://

dx.doi.org/10.1007/s00580-009-0899-3.]

Shi, Xiaotao, Li, Dapeng, Zhuang, Ping, Nie, Fen, and Long, 

Liangqi, 2006, Comparative blood biochemistry of Amur 

sturgeon, Acipenser schrenckii, and Chinese surgeon, 

Acipenser sinensis: Fish Physiology and Biochemistry, 

v. 32, no. 1, p. 63–66. [Also available at http://dx.doi.

org/10.1007/s10695-006-7134-9.]

Thrall, Mary Anna, Weiser, Glade, Allison, Robin, and 

Campbell, T.W., 2012, Veterinary hematology and clinical 

chemistry (2d ed.): Wiley-Blackwell, 776 p.

U.S. Fish and Wildlife Service, 2008a, Biological procedures 

and protocols for researchers and managers handling pallid 

sturgeon: Billings, Mont., U.S. Fish and Wildlife Service, 

32 p.

U.S. Fish and Wildlife Service, 2008b, Pallid sturgeon 

(Scaphirhynchus albus) range-wide stocking and augmentation plan: U.S. Fish and Wildlife Service, 55 p.

Welker, T.L., and Drobish, M.R., 2009, Missouri River 

standard operating procedures for fish sampling and data 

collection: U.S. Army Corps of Engineers, Omaha District, 

v. 1.4, 208 p.

Zuccarelli, M.D., Kusakabe, M., Nakamura, I., Prentice, 

E.F., Young, G., and Ingermann, R.L., 2008, Acute stress 

response of Kootenai River white sturgeon Acipenser transmontanus Richardson reflected in peritoneal fluid and blood 

plasma: Journal of Fish Biology, v. 72, no. 7, p. 1831–1840. 

[Also available at http://dx.doi.org/10.1111/j.1095-

8649.2008.01840.x.]
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 191

Appendix 6. Free-Embryo Drift Experiments in an Experimental Stream

Methods

Experiments were done indoors in an endless oval 

stream tank (fig. 6–1). Availability of tanks and pallid sturgeon embryos necessitated multiple trials in a series from 

May through July 2012. Testing began at hatch and ended just 

before complete yolk absorption. Fish were not fed during the 

trials.

Pallid sturgeon embryos were obtained from three different facilities through time for the study trials: Neosho 

National Fish Hatchery (NNFH), Neosho, Missouri; Columbia 

Environmental Research Center (CERC), Columbia, Mo.; 

and Gavins Point National Fish Hatchery (GPNFH), Yankton, South Dakota. Embryos, except all those in the second 

of two spawns from GPNFH, were obtained immediately 

after fertilization and before use of Fuller’s earth so that they 

retained their adhesive properties and could be attached to a 

cobble substrate. Upon collection at the hatchery, or receipt by 

overnight courier, the embryos were divided into two groups 

for hatching: (1) those attached to a cobble substrate (approximately 50 embryos) and placed in the stream or (2) those 

hatched in a floating mesh basket or McDonald jar in the 

stream. The embryos in the basket and McDonald jar served 

both as a control to assess mortality because of water quality 

conditions without current, and to provide a pool of embryos 

at the identical developmental stage to replace mortalities 

within the artificial stream. A second batch of newly fertilized 

embryos from GPNFH was shipped overnight to Columbia, 

Mo., and all were reared in a McDonald jar in the test stream.

Background

Pallid sturgeon (Scaphirhynchus albus) continue to 

show limited or no recruitment in the Missouri River despite 

evidence of spawning by wild and by hatchery-origin adults. 

Hypotheses for recruitment failure have shifted to questions about survival of early life stages, from fertilization to 

“settling” of exogenously feeding larvae in channel-margin 

habitats. A critical component of this process is thought to be 

drift of newly hatched free embryos.

Scope and Objectives

The goal of this study is to describe the drift behavior of 

free-embryo pallid sturgeon from hatch to the end of dispersal. 

Aspects of the study will repeat the work of Kynard and others 

(2007). The objectives are the following: (1) to measure the 

depth at which free embryos and larvae drift; (2) to identify 

where free embryos and larvae are in the drift in the vertical 

and cross-channel dimensions (surface, bottom, inside bends, 

outside bends); (3) to measure the rate at which free embryos 

and larvae drift relative to water velocity; (4) to quantify the 

days post-fertilization or post-hatch or at what cumulative 

thermal units (CTU) the larvae stop drifting; (5) to identify 

environmental conditions where larvae are located when they 

stop drifting; and (6) to understand the ability of different 

developmental stages to maintain position in flowing at different water velocities.

2.44 meters

0.38 meters

Pool

Flow

1.6 meters

Outflow

Drain

Outflow

Inlet

Inlet

B

C

D

Viewing platform

Depth tiles

G

A

F E

Deflector or wing dike

Figure 6–1. Diagram of the oval stream tank used in the free-embryo drift experiments.
192 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

A fiberglass endless oval stream with pool configuration 

was used to make drift measurements (Frigid Units, Toledo, 

Ohio, fig. 6–1). The stream was 24 centimeters (cm) deep 

and 38 cm wide at the bottom, and consisted of a straight run 

section 244 cm long and a run section 122 cm long followed 

by a pool section 122 cm in diameter. A piece of plexiglass 

attached to the wall of the pool where it joined the channel 

created a ‘dike-like’ effect causing an eddy to form behind it. 

A second, larger piece of plexiglass created a wall across the 

pool extending from the inlet end of the channel to the outlet 

end. A ‘ledge-like’ drop from the bottom of the channel into 

the pool was 25 cm. Water depth in the pool was 49 cm. Water 

was one-pass flow through and entered the stream system at 

two positions through holes drilled in a 3-foot -one-half-inch 

PVC pipe extending at a 45 degree (o) angle from inlet to 

bottom of channel. Water drained from the surface through an 

overflow standpipe covered in fine mesh to prevent loss of free 

embryos.

Stream-drift rate and position measurements were made 

in a single location in the longer run channel section. A 

38-cmx38-cm sheet of white plastic was affixed to the bottom 

of the stream channel with silicone adhesive to improve contrast and facilitate observations of the drifting free embryos. 

Slightly upstream, two plexiglass tiles (38 cmx10 cm) were 

attached across the width of the stream channel. The lower 

tile was placed at two-thirds water depth, or 7.7 cm above 

the channel bottom, and the upper tile at 15.3 cm above the 

channel bottom. The tiles divided the water column into three 

sections (bottom, mid-water, and top) to locate drifting free 

embryos in the stream. Additionally, the bottom of the pool 

was gridded to facilitate documentation of free-embryo location in the pool.

Lighting was minimal throughout the study to mimic 

conditions in the Missouri River (about 3–20 lux). When light 

was necessary, red lights were used. Video cameras, installed 

above the stream channel observation platform and in the 

pool at the base of the dropoff, recorded constantly throughout the drift experiments. A TidbiT temperature data logger 

(Onset Computer Company, Bourne, Massachusetts) recorded 

water temperature at intervals throughout the study. Current 

velocity was measured at random times daily at seven locations in the channel and three in the pool with a flow meter 

(Marsh-McBirney, Hach, Loveland, Colorado). Measurements 

were made at three locations in the channel along a transect 

perpendicular to the flow. Measurements were made at three 

depths (4, 11, and 20 cm from the bottom) at each point along 

the transect.

Measurements of drift rate and position in the channel 

and pool were made at 3-hour intervals from hatch until the 

end of the trial. Drift was measured by counting the number 

of free embryos that passed over the observing platform in 

a 5-minute period with the observer noting the upstream or 

downstream orientation of the free embryo. Location in the 

channel was also measured in a 5-minute period with the 

observer recording the vertical (bottom, mid, or top) and horizontal position (right side, center, or left side) of the drifting 

free embryo. Location in the pool was measured by turning 

the water off for 5 minutes, recording the position of the free 

embryos, waiting 5 minutes, then again recording the position 

of the free embryos. Numbers and status (live or dead) of free 

embryos in the stream system were evaluated daily. Dead free 

embryos were replaced daily by same-age free embryos that 

had been held in the stream in a floating basket or in aquaria 

in the laboratory so as to maintain five free embryos in the 

stream.

On days 11, 13, and 15 post-hatch, 9 individuals from 

trial 2 were tested to determine their ability to withstand swimming against a current. Testing consisted of a fish being placed 

in the chamber of the stamina instrument and the water velocity slowly being increased. Each fish was placed in one of 

three 5-liter (L) swim tunnel respirometers (Loligo Systems, 

Denmark). The fish was placed in the test section of the tunnel 

(30x7.5x7.5 cm) and acclimated at a velocity 17.8 centimeters 

per second (cm/s) for 5 minutes. After the acclimation period, 

the velocity was increased by 5.09 cm/s every 3 minutes. The 

test concluded when the fish fatigued (was swept downstream 

and was impinged on the screen for 5 seconds). Following the 

trial, total length and weight for each fish was obtained. The 

time to fatigue and the velocity of the water at fatigue were 

recorded.

Results

Trial 1

On May 9, 2012, 89 newly fertilized embryos were 

obtained from the NNFH. Fertilization rate was 91 percent. Of 

those 89, 49 embryos were attached to the rock substrate and 

placed in the stream channel. The remaining embryos were 

placed in a mesh basket that was floated in the stream. Mortality was similar between embryos in the basket and those in the 

stream substrate. By 2 days post-fertilization (dpf), 60 percent 

of the embryos in the basket died with no additional mortality until hatch. Mortality in the stream substrate was similar 

but happened during a longer time. By 5 dpf, 60 percent of 

embryos in the substrate died. Hatching began May 15 or 

at 6 dpf. Video showed softening of the chorion as hatching enzymes progressively thinned the membrane. When the 

embryo was free of the egg, it initially fell down below the 

rock substrate, and then was swept into the current. At 3 days 

post-hatch (dph), all but one free embryo was dead. Average daily water temperature during the study was 17.9 plus 

or minus (±) 0.5 oC, and dissolved oxygen concentration was 

8.0±0.3 milligram per liter (mg/L).

Trial 2

A pallid sturgeon from the CERC captive population 

was spawned on May 23, 2012, and eggs were fertilized with 

cryopreserved milt because no other milt was available. Fertilization was extremely poor; therefore, 4 sets of 50 embryos 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 193

on rock substrates were placed in the stream. An additional 

20 embryos were placed in a McDonald jar suspended in the 

stream and supplied with stream water. Hatching began on 

May 29, 2012. On day 1 post-hatch, 20 dead and 5 living free 

embryos were recovered in the pool below the ledge where the 

channel meets the pool. All unhatched and hatched embryos 

were put in floating baskets to ensure uniform conditions 

for growth and development of replacement embryos. The 

bottom of the pool was covered with black plastic and gravel 

to reduce potential attraction to the previously white bottom. Ten free embryos (2 dph) from the basket were added 

to the stream. Within 24 hours, nine were recovered in the 

gravel dead. Subsequently, 11 additional free embryos age 

3 dph added to the stream were all found dead, except for 1, 

within 24 hours. Five same-age free embryos (3 dph) from 

the floating basket were added to the stream for a total of six 

live free embryos. One of these died on 4 dph. On 5 dph, no 

free embryos could be observed in the stream. On 6 dph, four 

living free embryos were recovered from the gravel. Five free 

embryos 6 dph were added to the stream, and three of these 

were still alive on 10 dph. Daily water temperature averaged 

18.3±0.5 o

C, and average dissolved oxygen concentration was 

9.1±0.4 mg/L during the study.

Trial 3

On June 22, 2012, GPNFH provided 96 embryos. Of 

those 96, 46 were attached to the rock substrate in the stream 

and 50 were placed in a McDonald jar in stream. Post-fertilization viability of embryos was 56 percent. Hatching began 

on 6 dpf (June 28, 2012). As free embryos died, they were 

replaced with same-age embryos to attempt to maintain five 

free embryos in the stream. Mortality continued until 7 dph at 

which time the fish appeared to have settled out of the drift. 

Daily water temperature averaged 19.3±0.8 oC, and dissolved 

oxygen concentration averaged 9.6±0.3 mg/L.

Trial 4

A second batch of eggs was fertilized at GPNFH on June 

27, 2012. These embryos were shipped to CERC by overnight 

courier and were, therefore, not attached to a rock substrate. 

Embryos arrived on July 3, 2012 (6 dpf). Hatching began 

the next day. On 1 dph, five free embryos were added to the 

stream. Same-age free embryos were added daily to replace 

dead fish. Mortality ceased on 8 dph at which time fish in the 

stream appeared to have settled out of the drift. Average daily 

temperature during the study was 20.1±0.6 oC, and dissolved 

oxygen concentration averaged 8.1±0.3 mg/L.

Temperature and Velocity

Temperatures in the test stream system were similar 

among the four trials, whereas water temperature increased 

slightly between trial 1 and the trial 4. As a result, cumulative thermal units for days post-hatch were not exactly the 

same among the trials (fig. 6–2). Overall, average velocity in 

the tank was 13 cm/s, the mode was 12 cm/s, and the median 

13.5 cm/s. The highest mean velocities were at points A and E 

at midwater and the surface (23–29 cm/s; table 6–1). Lowest 

mean velocities were at points A and E on the inside of the 

channel nearest the bottom (table 6–1).

EXPLANATION

0 2 4 6 8 10 12 14

0

50

100

150

200

250

Trial 1

Trial 2

Trial 3

Trial 4

Day post-hatch

Cumulative thermal units

Figure 6–2. Relation between 

days post-hatch and cumulative 

thermal units calculated for 

trials 1–4.
Table 6–1. Mean, standard deviation, and range (in parentheses) of velocity in centimeters per second at seven locations (see figure 6–1) in thre

stream channel. [cm, centimeter; ±, plus or minus] Location 4 cm from channel bottom 11 cm from channel bottom 20 cm from ch

Inside Middle Outside Inside Middle Outside Inside Mid

A -1.3±0.7 (-1.9–-0.5) 18.3±1.3 (17.0–19.5) 14.7±1.0 (13.6–15.7) 0.4±0.8 (-0.1–1.4) 24.7±0.8 (24.0–25.5) 16.8±1.3 (15.3–17.8) 4.1±0.6 (3.5–4.6) 16.4

(15.7–

B 10.1± 0.5 (9.5–10.5) 9.5±0.3 (9.3–9.8) 8.7±1.0 (8.2–9.8) 12.6±0.5 (12.1–12.9) 12.0±0.5 (11.5–12.5) 11.2±0.9 (10.4–12.2) 15.4±0.7 (14.6–15.8) 17.2

(16.6–

C 13.5± 0.2 (13.4–13.7) 13.7±0.1 (13.6–13.8) 14.6±0.5 (14.2–15.1) 12.9±0.0 (12.8–12.9) 12.5±0.5 (12.0–13.0) 14.1±0.2 (13.0–14.3) 12.2±0.4 (11.8–12.6) 11.4

(10.8–

D 15.8±1.0 (15.3–17.0) 3.3±0.6 (2.6–3.8) 17.0±0.1 (17.0–17.1) 14.2±0.4 (13.8–14.5) 6.9±0.7 (6.2–7.5) 16.2±0.7 (15.7–17.0) 10.8±0.3 (10.5–11.0) 5.6±

(4.6–

E -0.2±1.8 (-1.9–1.7) 11.5±0.7 (10.7–12.0) 12.3±1.8 (10.3–13.7) 1.8±3.3 (-1.4–5.2) 18.9±0.8 (18.2–19.7) 19.7±3.7 (15.8–23.2) 6.5±0.7 (6.0–7.3) 24.8

(23.4–

F 17.9±0.8 (17.4–18.7) 17.3±0.2 (17.2–17.5) 12.5 20.3±0.5 (19.9–20.8) 15.9±0.4 (15.5–16.4) 11.0±0.4 (10.6–11.5) 20.6±0.5 (20.1–20.9) 8.6±

(7.9–

G 16.5±0.7 (16.0–17.3) 13.0±0.2 (12.8–13.3) 10.4±0.6 (9.8–11.0) 17.0±0.3 (16.7–17.4) 13.7±0.1 (13.5–13.8) 11.6±0.4 (11.2–12.0) 16.8±0.5 (16.5–17.4) 13.3

(13.1–
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 195

Mortality

Mortality increased until 4 dph, and then began to 

decrease. After day 7 or day 8 mortality had ceased in individual trials (fig. 6–3). Dead fish were exclusively found on the 

bottom of the pool in an eddy most commonly at the juncture 

of the channel with the pool. A video camera placed at this 

location recorded moribund free embryos twitching and spinning on the bottom of the pool for as much as 18 hours before 

dying. Dead free embryos recovered at 3 dph showed signs of 

edema and hemorrhage. A subsample of free embryos 6 dph 

was sent to the U.S. Fish and Wildlife Service, Fish Health 

Center in LaCrosse, Wisconsin, where it was determined that 

the fish were disease- and iridovirus-free (Corey Puzach, oral 

commun., 2012).

Drift, Position, Stamina

Until 6 dph, very few free embryos drifted across the 

observation platform, and peak drifting was observed between 

6 and 9 dph (fig. 6–4). After 9 dph, observations of drifting 

free embryos decreased. Observations indicated the fish were 

beginning to hold position in the stream on the bottom of the 

tank. In the pool, free embryos were most often observed at 

the bottom of the tank below where the channel attached to the 

pool and in the eddy created by the plexiglass ‘dike’ (fig. 6–5). 

An analysis on ranks of the mean number of free embryos to 

pass the observation depth tiles for trials 2, 3, and 4 indicated 

differences in position associated with days post-hatch, but 

not time of day (Kruskal-Wallis rank sum test, p less than 

(<)0.05). From 1 dph through 7 dph, free embryos were more 

likely to be observed in the bottom third of the tank (significant differences on 1, 4, 5, 6, and 7 dph) (fig. 6–6). After 

7 dph, free embryos were more likely to be observed drifting 

past the observation tiles at the surface (significant 11 dph) 

(fig. 6–6). While there were changes in vertical position 

through time, a difference in lateral position within the stream 

tank was noted only at 7 dph when more fish were observed 

midstream than at the inside bend position (data not shown).

In swim tunnel studies, larval sturgeon 11 dph withstood a current of as much as 30±5 cm/s for 12±4 minutes. 

Larval sturgeon at 13 dph withstood a current of as much as 

39±3 cm/s for 16 ± 2 minutes, and those at 15 dph withstood 

a current of as much as 38±3 cm/s for 14±2 minutes. Sturgeon 

younger than 11 dph and smaller than 18 mm could not be 

tested because they were too small for the chamber.

4

3

3

4

3

3

3

2

1

Day post-hatch

0 2 4 6 8 10 12

0

20

40

60

80

100

Mortality, in percent, mean plus standard deviation

Figure 6–3. Percent mortality (mean and standard deviation) of pallid sturgeon free embryos per 

days post-hatch. Numbers above the bars indicate the number of trials.
196 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Day post-hatch

0 2 4 6 8 10 12

Mean number of daily observations

0

2

4

6

8

10

12

14

16

18

Figure 6–4. Daily observations (mean and standard deviation) of free embryos drifting past a fixed 

point normalized to the number of free embryos in the stream, 0–12 days post-hatch.

Trial

Neosho National

Fish Hatchery

Columbia

Environmental

Research Center

Gavins Point

National Fish

Hatchery trial 1

Gavins Point

National Fish

Hatchery trial 2

0

20

40

60

80

100

Frequency, in percent 

Ledge

Dike

EXPLANATION

Figure 6–5. Frequency of free embryos near 

the pool ledge and dike eddy as percent of the 

total number of observations during each trial.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 197

Summary

In this set of experimental trials the drift of free embryos 

was diminished for about 6 days post-hatch, apparently by 

enhanced mortality of very young free embryos. Drift peaked 

6–9 days post-hatch as surviving free embryos were transported, mostly passively, around the experimental stream tank. 

After 9 days post-hatch free embryos had developed the ability 

to hold their position in the current at prevailing velocities. 

These results indicate that the first several days post-hatch are 

critical to survival. Many factors could have contributed to the 

early mortality experienced in these initial trials; however, the 

possibility that continuous drift at velocities as low as 20 centimeters per second may be stressful to free embryos should be 

explored. In a natural river environment mean velocities and 

turbulence would be substantially higher but there would also 

be diverse microhabitats in and among substrate that could 

serve as refugia. If 0–6 days post-hatch free embryos were 

in such sheltered areas, they would have decreased energetic 

demands, and could have greater survival than those in the 

experimental stream.

References Cited

Kynard, B., Parker, E., Pugh, D., and Parker, T., 2007, Use of 

laboratory studies to develop a dispersal model for Missouri 

River pallid sturgeon early life intervals: Journal of Applied 

Ichthyology, v. 23, p. 365–374. [Also available at http://

dx.doi.org/10.1111/j.1439-0426.2007.00908.x.]

*

* *

*

*

*

*

Bottom

Midwater

Surface

EXPLANATION

Day post-hatch

0 2 4 6 8 10 12

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Mean number of free embryos

Significant differences among 

locations within a day 

Figure 6–6. Mean number of drifting free embryos and water column positions recorded at a fixed 

point per days post-hatch. Asterisks indicate significant differences among locations within a day.
198 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Appendix 7. Field Studies of Scaphirhynchus Sturgeon Embryo, Larvae, and 

Young-of-Year Dispersal, Distribution, and Habitat Use in the Lower Missouri 

River

not result in retention in channel margins, the prolonged drift 

period of free embryo sturgeon and the prevailing Missouri 

River velocities may require a long segment of free-flowing 

river to complete the ontogenetic drift cycle. If, as newer studies are showing for other sturgeon species, free embryos do 

not drift immediately and instead remain in close proximity to 

incubation sites, then hypotheses regarding long-distance drift 

before feeding are invalid. Authors have suggested that free 

embryos that drift into the headwaters of reservoirs probably 

do not survive (Kynard and others, 2007). The probability 

and benefits of retention in channel margins, rather than direct 

downstream transport in the thalweg, is an unknown, but critical factor in determining effective drift distance. The number 

of sturgeon free embryos produced in the Lower Missouri 

River, the proportion retained, and the proportion of those that 

are transported into the Mississippi River, and survive there, 

are unknown quantities. Locations along the channel where 

drifting sturgeon embryos are retained, or settle, and the availability of suitable habitat for early feeding may be critical for 

survival and recruitment.

Scope and Objectives

During 2011, habitat studies began to develop the 

hydraulic and geomorphic context of free embryo drift and 

potential settling areas where free embryos may be extracted 

from the main channel or where exogenously feeding larvae 

may swim under their own volition. This work was coordinated with an age-0–juvenile sampling program being carried 

out by the U.S. Fish and Wildlife Service (FWS, Columbia 

Fisheries) that is intended to assess performance of shallowwater habitat restoration projects. This ongoing research is 

intended to address the potential for young sturgeon to be 

retained within the Lower Missouri River, but the design is not 

intended to evaluate the export of young sturgeon out of the 

Lower Missouri River. To evaluate export to the Mississippi 

River a systematic free-embryo sampling effort was done from 

mid-April through early-October near the confluence with the 

Mississippi River. The objectives of this initial study were the 

following: (1) to determine our power to detect drifting freeembryo sturgeon in the Lower Missouri River, (2) to determine the timing and spatial extent of sturgeon spawning in the 

Lower Missouri River, (3) to assess the species composition 

of sturgeon embryos in the Lower Missouri River, and (4) to 

assess the export of early life-stage sturgeon into the Mississippi River based upon our power to detect sturgeon embryos. 

This work was completed in the Lower Missouri River 

33.3 miles (mi) upstream of the confluence with the Mississippi River near St. Charles, Missouri (fig. 7–1). This work 

was designed to evaluate the contribution of early life stage 

Background

Recruitment of pallid sturgeon (Scaphirhynchus albus) 

to the adult population is limited or nonexistent throughout 

most of the Missouri River (U.S. Fish and Wildlife Service, 

2007). Limited numbers of larval and young-of-year sturgeon 

have been collected from the Lower Missouri River; samples 

collected prior to this study have been genetically confirmed 

to be entirely shovelnose. The low numbers of young sturgeon in Lower Missouri River samples may be explained by 

limited spawning, lack of successful spawning, poor fertilization, high mortality, ineffective sampling methods, inadequate 

sampling of drift and settling locations, or rapid dispersal and 

transport of sturgeon free embryos from the Missouri River 

into the Mississippi River. Although documentation of spawning by pallid sturgeon is a critical first step towards assessing 

population status and recovery, successful spawning does 

not ensure successful recruitment to the juvenile or adult life 

stages. Rather, biotic and abiotic factors operating during the 

free-embryo life stage (hatch to exogenous feeding) may limit 

survival and population growth (Dettlaff and others, 1993). 

This life stage commonly functions as a recruitment bottleneck for fishes because of decreased mobility and sensory 

ability, and increased vulnerability to anthropogenic environmental alteration (Scheidegger and Bain, 1995; Humphries 

and others, 2002). Given the sensitivity of the free-embryo life 

stage to mortality, it is imperative to identify determinants of 

post-hatch survival in shovelnose and pallid sturgeon (Bajer 

and Wildhaber, 2007; Wildhaber and others, 2007, 2011; Steffensen and others, 2013). Identification of critical environmental factors, developmental or behavioral changes, or habitat 

requirements during the free-embryo life stage can be used to 

enhance pallid sturgeon recovery efforts.

Shovelnose and pallid sturgeon begin to hatch in the laboratory after 4 to 5 days at 17–18 degrees Celsius (°C). After 

hatching, laboratory studies suggest that shovelnose sturgeon 

(Scaphirhynchus platorynchus) drift for a period of as much as 

6 days and pallid sturgeon free embryos drift for 11–17 days 

(Kynard and others, 2007; Braaten and others, 2008); however, recent studies using modified laboratory systems more 

representative of a natural river incubation site have raised 

questions on findings on drift behavior from the earlier studies 

(see “Appendix 6”). Benthic orientation and feeding begins 

near the end of the free-drifting period. The total distance that 

sturgeon free embryos drift during ontogenetic development 

is dependent on substrate conditions, water velocity, localized 

hydraulic conditions, and temperature (Kynard and others, 

2007; Braaten and others, 2008). Mean velocities measured 

on the Missouri River are typically 0.4–1.2 meters per second 

(m/s) (Reuter and others, 2009). If localized hydraulics do 
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 199

sturgeon from the Missouri River to the Mississippi River and 

provide some relative indication of the importance of the Mississippi River as nursery habitat for young-of-year shovelnose 

and pallid sturgeon.

Methods

Since 2009, sampling efforts for the Comprehensive 

Sturgeon Research Project (CSRP) have focused on capturing newly hatched and drifting free embryos immediately 

downstream of probable pallid sturgeon spawning sites. This 

sampling design has been termed “verification sampling” 

because it was intended only to verify hatch of newly spawned 

embryos. “Systematic sampling” for free-embryo and larval 

sturgeon was initiated in 2012 to assess export of young sturgeon from the Lower Missouri River to the Mississippi River. 

A suitable sampling site was identified near St. Charles, Mo., 

downstream of the last major tributary on the Lower Missouri 

River and upstream of the confluence with the Mississippi 

River. The sampling site was representative of cross-sections 

of the Lower Missouri River with the thalweg on the outside 

bend and a wing dike-sand bar complex on the inside bend. It 

was not affected by backwater from the Mississippi River during high-water events and had little commercial vessel traffic. 

Systematic sampling focused on a single channel cross-section 

to provide a relative indication of the importance of the Mississippi River as nursery habitat for young-of-year shovelnose 

and pallid sturgeon spawned in the Missouri River. A transect 

with eight equidistant sampling stations was established across 

the river channel (fig. 7–1).

Systematic sampling for free-drifting embryos in the 

Lower Missouri River began in mid-April and continued 

through early-October 2012. Conditions suitable for sturgeon 

spawning are expected to vary along the length of the Lower 

Missouri River and potentially among the various tributaries. 

The sampling period was designed to capture drifting embryos 

that might be spawned early in the main stem Missouri River 

near the confluence with the Mississippi River, and later in the 

Missouri River nearer the Gavins Point Dam and in tributaries. 

Sampling for drifting free embryos into October was designed 

to detect spawning episodes that may be delayed because of 

unusual or altered environmental conditions. Late sampling also 

may detect the presence of fall spawning within the population.

An 8-meter (m) research vessel outfitted with paired 

booms and winches was deployed to sample the stations along 

the transect at daily to biweekly intervals. The research vessel was anchored during net deployment (“passive sampling”). 

Paired, 0.5-m diameter ichthyoplankton nets (750 micrometer 

[μm] mesh) were equipped with General Oceanics velocity 

meters and attached to 100-pound (lb) (45.4 kilograms [kg]) 

Columbus-style sounding weights. Samples were collected just 

above the river bottom and at midwater column. The sample 

duration was 5 to 20 minutes depending on the amount of 

coarse organic material in the water column during the sampling effort. In the interest of safety, samples were not collected 

during periods of high flow or heavy debris loading. Additionally, midwater column samples were not collected if water depth 

was less than 2 m. Velocities and depths along each transect 

were determined at representative flows using an acoustic Doppler current profiler (ADCP; see “Appendix 3”). Representative 

flows were within 10 percent of discharges on sampling dates.

Ichthyoplankton samples were sorted on board the 

research vessel shortly after collection. All free embryos 

identified as sturgeon (Scaphirhynchus spp.) or paddlefish 

(Polyodon spathula) were preserved in 70-percent ethanol for 

more precise identification in the laboratory. Developmental 

characteristics were examined in the laboratory and used to 

identify individual specimens to genus and developmental 

stage if condition allowed. Scaphirhynchus free embryos were 

sent for species determination using genetic analyses at Southern Illinois University Carbondale.

Results

Preliminary sampling was done in the vicinity of the 

site from April 17 through 19, 2012, to test collection protocols and refine the location of the transect and stations based 

on local conditions. During these 3 days of pilot sampling, 

4 sturgeon and 22 paddlefish free embryos and larvae were 

collected and preserved in 70-percent ethanol. The length of 

sturgeon ranged from 7.88 millimeters (mm) to 10.09 mm. 

Size and developmental characteristics indicated that the 

sturgeon were approximately 1 day post-hatch or younger. The 

length of paddlefish ranged from 8.58 mm (estimated as less 

than 1 day post-hatch) to 15.43 mm (estimated at 8 to 11 days 

post-hatch). Water temperatures recorded during this time 

ranged from 14.9 °C to 16.2 °C. The four sturgeon were later 

sent to Southern Illinois University Carbondale for genetic 

species determination. These specimens were collected prior 

to the establishment of the transect and sampling stations, and 

are not included in the analysis for this report.

Eight equidistant sampling stations were established 

along the transect across the channel of the Missouri River 

near St. Charles, Mo. (fig. 7–1). The stations were sampled for 

65 days between April 23 and October 4, 2012. The number of 

sampling days at each station varied because of river conditions and associated safety concerns (table 7–1). Stations 1, 

2, and 3 could not be sampled during summer and fall 2012 

because of drought conditions and subsequent low flows in the 

Lower Missouri River. Sampling at these stations was discontinued when water depth dropped below approximately 0.75 m 

during late May or early June. Station 7 was only sampled on 

3 days (May 22, 23, and 24, 2012) because of safety concerns 

associated with anchoring the research vessel in the swift 

current velocities of the navigation channel (greater than 

[>]2.5 meters per second [m/s], >10 m deep). Station 8 was 

not sampled because the relative proximity to the revetment 

made anchoring the research vessel impractical. Sampling 

period and numbers of sturgeon and paddlefish collected at 

each station are summarized in table 7–1.
200 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Study area

90°32’ 90°31’45” 90°31’30”

38°44’

38°43’45”

7

6

5

4

3

2

1

8

33.6

33.5

33.4

33.3

33.2

33.1

EXPLANATION

Sampling location and number

0 50 100 200 METERS

0 250 500 1,000 FEET

River mile marker—Number is distance 

upstream from the confluence with 

the Mississippi River, in miles

Digital imagery from U.S. Department of Agriculture 

National Agriculture Imagery Program digital data, 2012

Universal Transverse Mercator projection, zone 15

33.6

River miles from U.S. Army Corps of Engineers, 1960

1

Figure 7–1. Free-embryo sampling locations in the Lower Missouri River, near river mile 33.3.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 201

A total of 336 sturgeon and 323 paddlefish free embryos 

and larvae was collected at the 7 stations during 2012 sampling efforts. Of these, 321 sturgeon were collected at the 

7 stations from April 24 to June 18 (tables 7–2 to 7–8). Water 

temperatures during this time ranged from 14.8 °C to 27.2 °C. 

The length of sturgeon collected during this time ranged from 

6.67 mm (estimated as less than 1 day post-hatch [dph]) to 

35 mm (estimated at 30 or more dph; fig. 7–2). All 323 paddlefish were collected from April 23 to June 12 (tables 7–2–7–8). 

Water temperatures during this time ranged from 14.8 °C to 

24.6 °C. The length of paddlefish collected during this time 

ranged from 7 mm (estimated as less than 1 dph) to 49 mm 

(estimated at 35 or more dph; fig. 7–3). No paddlefish were 

collected after June 12, 2012.

A total of 15 sturgeon was collected from late June 

through September 2012. Two sturgeon were found at station 6 during early summer on June 26 and 27 (table 7–7) 

when recorded water temperatures ranged from about 26.1 °C 

to 27 °C. Size and developmental characteristics indicated 

that both sturgeon were approximately 12 or more dph. No 

sturgeon were found during 14 sampling days from July 9 to 

August 22 when water temperatures ranged from 31 °C to 

25.3 °C. During late summer and early fall, 13 sturgeon were 

collected during 6 sampling days from August 22 to September 20 at station 6; no sturgeon were collected at station 4 or 

5 (tables 7–5 and 7–6). Water temperatures during this time 

ranged from a high of 26.3 °C to a low of 21.2 °C. The length 

of the sturgeon free embryos and larvae collected during late 

summer ranged from 7.14 mm (estimated as less than 1 day 

post-hatch) to 36 mm (estimated at 30 or more dph; fig. 7–2).

Numbers and mean density of sturgeon and paddlefish 

collected varied among sampling stations (tables 7–2 to 

7–10). Sturgeon were found in highest numbers and densities near and in the thalweg at stations 6 and 7. Mean density 

of sturgeon was highest at station 7 (2.71 sturgeon/100 cubic 

meters [m3

]) where 91 were collected during 3 days of sampling in May (table 7–9). Excluding station 7, mean density 

of sturgeon was highest at station 6 (0.23/100 m3) where 186 

sturgeon were collected during 63 sampling days. Mean density of sturgeon was less than or equal to 0.10 sturgeon/100 m3 

at stations 1–5. Mean density of sturgeon was lowest at station 

1 (0.02 sturgeon/100 m3) where only one was collected during 

8 sampling days. Mean density of paddlefish was also highest 

at station 7 (1.34 paddlefish/100 m3) during the 3 sampling 

days; however, paddlefish were more dispersed among all 

stations than were sturgeon (table 7–10). Paddlefish were collected in higher numbers than sturgeon at all stations except 6 

and 7. Paddlefish were not found after June 12.

Densities of free embryos and larvae sampled during 

2012 varied with time among sampling stations and dates 

(tables 7–9 and 7–10). The highest mean density of sturgeon was recorded at station 7 on May 23 with 3.22 sturgeon/100 m3

, closely followed by May 22 and 24, each 

with 2.45 sturgeon/100 m3 (table 7–9); however, this station 

Table 7–1. Summary of sturgeon and paddlefish free embryo and 

larvae collection efforts in the Missouri River near St. Charles, 

Missouri, during 2012.

Station First date 

sampled

Last date 

sampled

Number 

days 

sampled

Number 

sturgeon 

collected

Number 

paddlefish 

collected

1 4/24/2012 5/22/2012 8 1 15

2 4/24/2012 5/17/2012 11 5 21

3 4/24/2012 6/7/2012 18 14 42

4 4/24/2012 10/4/2012 60 16 31

5 4/23/2012 10/4/2012 65 23 61

6 4/23/2012 10/4/2012 63 186 109

7 5/22/2012 5/24/2012 3 91 44

Table 7–2. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 1.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/24/2012 -- -- -- -- -- -- -- --

4/25/2012 -- -- -- -- 2 12.49 12.12 12.85

5/2/2012 1 6.89 6.89 6.89 7 14.73 12.47 16.76

5/8/2012 -- -- -- -- 2 20.02 17.03 23

5/9/2012 -- -- -- -- -- -- -- --

5/15/2012 -- -- -- -- 2 25 21 29

5/16/2012 -- -- -- -- 2 25 24 26

5/22/2012 -- -- -- -- -- -- -- --
202 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Table 7–3. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 2.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/24/2012 -- -- -- -- 1 14.46 14.46 14.46

4/25/2012 -- -- -- -- -- -- -- --

4/26/2012 -- -- -- -- -- -- -- --

5/1/2012 2 5.7 1

3.49 7.91 5 13.95 12.85 15.49

5/2/2012 1 7.16 7.16 7.16 4 13.47 13.19 13.84

5/3/2012 -- -- -- -- 7 13.96 12.37 14.63

5/8/2012 1 15.06 15.06 15.06 1 22 22 22

5/9/2012 1 16.83 16.83 16.83 -- -- -- --

5/15/2012 -- -- -- -- 2 25.5 24 27

5/16/2012 -- -- -- -- 1 23 23 23

5/17/2012 -- -- -- -- -- -- -- --

1

Partial specimen.

Table 7–4. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 3.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/24/2012 -- -- -- -- 2 13.92 12.76 15.07

4/25/2012 1 7.46 7.46 7.46 2 12.98 11.22 14.74

4/26/2012 1 6.96 6.96 6.96 3 11.56 8.08 14.11

5/1/2012 7 7.76 7.06 8.21 18 13.42 8.2 14.95

5/2/2012 2 8.41 8.28 8.54 4 14.33 12.86 16.25

5/3/2012 1 14.01 14.01 14.01 7 14.35 13.93 15.04

5/7/2012 -- -- -- -- -- -- -- --

5/8/2012 -- -- -- -- 2 17.39 15.1 19.68

5/9/2012 -- -- -- -- 2 17.5 14.99 20

5/10/2012 1 6.67 6.67 6.67 -- -- -- --

5/15/2012 1 17.5 17.5 17.5 -- -- -- --

5/16/2012 -- -- -- -- 1 26 26 26

5/17/2012 -- -- -- -- 1 24 24 24

5/21/2012 -- -- -- -- -- -- -- --

5/29/2012 -- -- -- -- -- -- -- --

6/5/2012 -- -- -- -- -- -- -- --

6/6/2012 -- -- -- -- -- -- -- --

6/7/2012 -- -- -- -- -- -- -- --
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 203

Table 7–5. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 4.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/24/2012 -- -- -- -- 2 12.74 12.65 12.83

4/25/2012 -- -- -- -- 2 12.47 12.3 12.63

4/26/2012 -- -- -- -- 3 9.39 7 13.44

4/30/2012 1 7.7 7.7 7.7 3 13.85 13.31 14.45

5/1/2012 2 7.77 7 8.54 5 10.98 7.1 13.96

5/2/2012 1 7.18 7.18 7.18 5 15.01 12.83 18

5/3/2012 4 8.25 7.56 8.88 4 14.18 13.64 14.81

5/7/2012 -- -- -- -- 1 17.95 17.95 17.95

5/8/2012 -- -- -- -- 1 19 19 19

5/9/2012 -- -- -- -- 1 19 19 19

5/10/2012 -- -- -- -- -- -- -- --

5/14/2012 1 16.09 16.09 16.09 -- -- -- --

5/15/2012 2 13.23 7.46 19 1 20 20 20

5/16/2012 2 18.2 16.39 20 1 27 27 27

5/17/2012 -- -- -- -- 1 21 21 21

5/21/2012 1 21 21 21 -- -- -- --

5/22/2012 1 17.13 17.13 17.13 1 17.65 17.65 17.65

5/23/2012 -- -- -- -- -- -- -- --

5/29/2012 -- -- -- -- -- -- -- --

5/30/2012 -- -- -- -- -- -- -- --

5/31/2012 -- -- -- -- -- -- -- --

6/4/2012 -- -- -- -- -- -- -- --

6/5/2012 -- -- -- -- -- -- -- --

6/6/2012 -- -- -- -- -- -- -- --

6/7/2012 -- -- -- -- -- -- -- --

6/11/2012 1 16.21 16.21 16.21 -- -- -- --

6/12/2012 -- -- -- -- -- -- -- --

6/13/2012 -- -- -- -- -- -- -- --

6/14/2012 -- -- -- -- -- -- -- --

6/18/2012 -- -- -- -- -- -- -- --

6/19/2012 -- -- -- -- -- -- -- --

6/20/2012 -- -- -- -- -- -- -- --

6/21/2012 -- -- -- -- -- -- -- --

6/25/2012 -- -- -- -- -- -- -- --

6/26/2012 -- -- -- -- -- -- -- --

6/27/2012 -- -- -- -- -- -- -- --

7/9/2012 -- -- -- -- -- -- -- --

7/10/2012 -- -- -- -- -- -- -- --

7/11/2012 -- -- -- -- -- -- -- --

7/12/2012 -- -- -- -- -- -- -- --
204 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

7/23/2012 -- -- -- -- -- -- -- --

7/24/2012 -- -- -- -- -- -- -- --

7/25/2012 -- -- -- -- -- -- -- --

7/26/2012 -- -- -- -- -- -- -- --

8/6/2012 -- -- -- -- -- -- -- --

8/7/2012 -- -- -- -- -- -- -- --

8/8/2012 -- -- -- -- -- -- -- --

8/9/2012 -- -- -- -- -- -- -- --

8/21/2012 -- -- -- -- -- -- -- --

8/22/2012 -- -- -- -- -- -- -- --

8/23/2012 -- -- -- -- -- -- -- --

9/4/2012 -- -- -- -- -- -- -- --

9/5/2012 -- -- -- -- -- -- -- --

9/6/2012 -- -- -- -- -- -- -- --

9/17/2012 -- -- -- -- -- -- -- --

9/18/2012 -- -- -- -- -- -- -- --

9/19/2012 -- -- -- -- -- -- -- --

10/2/2012 -- -- -- -- -- -- -- --

10/3/2012 -- -- -- -- -- -- -- --

10/4/2012 -- -- -- -- -- -- -- --

Table 7–5. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 4.—

Continued

[--, no data; mm, millimeters]
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 205

Table 7–6. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 5.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/23/2012 -- -- -- -- 5 11.26 7.67 12.65

4/24/2012 1 7.74 7.74 7.74 3 13.36 12.72 14.62

4/25/2012 -- -- -- -- 2 12.7 12.52 12.87

4/26/2012 -- -- -- -- 5 13.13 8.14 16.04

4/30/2012 2 7.99 7.97 8.01 12 13.93 8.06 16.54

5/1/2012 -- -- -- -- 9 13.95 10.75 15.56

5/2/2012 2 8.35 8.21 8.48 2 11.58 10.5 12.65

5/3/2012 -- -- -- -- 9 14.35 11.06 16.02

5/7/2012 -- -- -- -- 2 15.56 15.53 15.58

5/8/2012 1 15.42 15.42 15.42 3 19.67 17.88 23

5/9/2012 1 15.37 15.37 15.37 -- -- -- --

5/10/2012 1 16.57 16.57 16.57 2 15.4 14.13 16.67

5/14/2012 -- -- -- -- 1 20 20 20

5/15/2012 3 16.7 15.45 18.25 1 22 22 22

5/16/2012 1 19 19 19 -- -- -- --

5/17/2012 3 11.07 7.07 18.69 1 22 22 22

5/21/2012 1 18 18 18 2 22.5 21 24

5/22/2012 -- -- -- -- 2 20 19 21

5/23/2012 1 21 21 21 -- -- -- --

5/24/2012 1 7.53 7.53 7.53 -- -- -- --

5/29/2012 3 15.88 13.59 18.17 -- -- -- --

5/30/2012 -- -- -- -- -- -- -- --

5/31/2012 -- -- -- -- -- -- -- --

6/4/2012 -- -- -- -- -- -- -- --

6/5/2012 -- -- -- -- -- -- -- --

6/6/2012 1 16.95 16.95 16.95 -- -- -- --

6/7/2012 -- -- -- -- -- -- -- --

6/11/2012 -- -- -- -- -- -- -- --

6/12/2012 -- -- -- -- -- -- -- --

6/13/2012 1 28 28 28 -- -- -- --

6/14/2012 -- -- -- -- -- -- -- --

6/18/2012 -- -- -- -- -- -- -- --

6/19/2012 -- -- -- -- -- -- -- --

6/20/2012 -- -- -- -- -- -- -- --

6/21/2012 -- -- -- -- -- -- -- --

6/25/2012 -- -- -- -- -- -- -- --

6/26/2012 -- -- -- -- -- -- -- --

6/27/2012 -- -- -- -- -- -- -- --

7/9/2012 -- -- -- -- -- -- -- --

7/10/2012 -- -- -- -- -- -- -- --
206 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

7/11/2012 -- -- -- -- -- -- -- --

7/12/2012 -- -- -- -- -- -- -- --

7/23/2012 -- -- -- -- -- -- -- --

7/24/2012 -- -- -- -- -- -- -- --

7/25/2012 -- -- -- -- -- -- -- --

7/26/2012 -- -- -- -- -- -- -- --

8/6/2012 -- -- -- -- -- -- -- --

8/7/2012 -- -- -- -- -- -- -- --

8/8/2012 -- -- -- -- -- -- -- --

8/9/2012 -- -- -- -- -- -- -- --

8/20/2012 -- -- -- -- -- -- -- --

8/21/2012 -- -- -- -- -- -- -- --

8/22/2012 -- -- -- -- -- -- -- --

8/23/2012 -- -- -- -- -- -- -- --

9/4/2012 -- -- -- -- -- -- -- --

9/5/2012 -- -- -- -- -- -- -- --

9/6/2012 -- -- -- -- -- -- -- --

9/17/2012 -- -- -- -- -- -- -- --

9/18/2012 -- -- -- -- -- -- -- --

9/19/2012 -- -- -- -- -- -- -- --

9/20/2012 -- -- -- -- -- -- -- --

10/1/2012 -- -- -- -- -- -- -- --

10/2/2012 -- -- -- -- -- -- -- --

10/3/2012 -- -- -- -- -- -- -- --

10/4/2012 -- -- -- -- -- -- -- --

Table 7–6. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 5.—

Continued

[--, no data; mm, millimeters]
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 207

Table 7–7. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 6.

[--, no data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

4/23/2012 -- -- -- -- 1 12.53 12.53 12.53

4/24/2012 -- -- -- -- 2 13.7 11.88 15.52

4/25/2012 1 8.77 8.77 8.77 6 11.13 7.05 13.16

4/26/2012 -- -- -- -- 6 10.37 7.01 13.38

4/30/2012 3 12.34 9.63 14.96 15 12.58 8.16 15.01

5/1/2012 3 7.73 7.36 8.12 8 13.2 8.57 15.29

5/2/2012 1 10.06 10.06 10.06 4 14.86 13.27 16.58

5/8/2012 1 14.02 14.02 14.02 7 18.24 15.45 20

5/9/2012 1 10.16 10.16 10.16 4 18.65 17.26 20

5/10/2012 4 14.99 13.16 17.46 7 16.71 14.71 20

5/14/2012 2 11.56 10.35 12.77 -- -- -- --

5/15/2012 7 14.98 11.12 18.37 3 21.33 20 23

5/16/2012 1 13.73 13.73 13.73 2 23 20 26

5/17/2012 -- -- -- -- -- -- -- --

5/21/2012 9 16.6 13.17 18.66 -- -- -- --

5/22/2012 18 14.47 1

5.97 17.61 5 19.98 16.45 24

5/23/2012 37 14.78 6.85 20.8 12 20.52 16 28

5/24/2012 14 14.28 9.58 16.42 3 19.33 18.99 20

5/29/2012 17 13.95 9.97 19 5 21.6 20 23

5/30/2012 11 13.37 9.81 16.7 8 21.63 19 25

5/31/2012 9 14.59 13.08 16.65 8 25 23 27

6/4/2012 -- -- -- -- 1 28 28 28

6/5/2012 4 17.08 15.99 18.25 -- -- -- --

6/6/2012 5 13.66 10.7 17.9 -- -- -- --

6/7/2012 7 11.56 8.14 13.92 -- -- -- --

6/11/2012 1 16.18 16.18 16.18 1 24 24 24

6/12/2012 3 18.74 15.3 25 1 49 49 49

6/13/2012 8 17.66 12.58 35 -- -- -- --

6/14/2012 2 17.57 17.51 17.63 -- -- -- --

6/18/2012 2 18.48 16.17 20.79 -- -- -- --

6/19/2012 -- -- -- -- -- -- -- --

6/20/2012 -- -- -- -- -- -- -- --

6/21/2012 -- -- -- -- -- -- -- --

6/25/2012 -- -- -- -- -- -- -- --

6/26/2012 1 18.98 18.98 18.98 -- -- -- --

6/27/2012 1 16.49 16.49 16.49 -- -- -- --

7/9/2012 -- -- -- -- -- -- -- --

7/10/2012 -- -- -- -- -- -- -- --

7/11/2012 -- -- -- -- -- -- -- --

7/12/2012 -- -- -- -- -- -- -- --
208 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

7/23/2012 -- -- -- -- -- -- -- --

7/24/2012 -- -- -- -- -- -- -- --

7/25/2012 -- -- -- -- -- -- -- --

7/26/2012 -- -- -- -- -- -- -- --

8/6/2012 -- -- -- -- -- -- -- --

8/7/2012 -- -- -- -- -- -- -- --

8/8/2012 -- -- -- -- -- -- -- --

8/9/2012 -- -- -- -- -- -- -- --

8/20/2012 -- -- -- -- -- -- -- --

8/21/2012 -- -- -- -- -- -- -- --

8/22/2012 1 12.26 12.26 12.26 -- -- -- --

8/23/2012 -- -- -- -- -- -- -- --

9/4/2012 5 23.11 16.21 36 -- -- -- --

9/5/2012 4 15.94 12.69 18.26 -- -- -- --

9/6/2012 1 16.94 16.94 16.94 -- -- -- --

9/17/2012 1 7.14 7.14 7.14 -- -- -- --

9/18/2012 -- -- -- -- -- -- -- --

9/19/2012 -- -- -- -- -- -- -- --

9/20/2012 1 19.15 19.15 19.15 -- -- -- --

10/1/2012 -- -- -- -- -- -- -- --

10/2/2012 -- -- -- -- -- -- -- --

10/3/2012 -- -- -- -- -- -- -- --

10/4/2012 -- -- -- -- -- -- -- --

1

Partial specimen.

Table 7–7. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 6.—

Continued

[--, no data; mm, millimeters]

Table 7–8. Summary of free embryo and larval sturgeon and paddlefish collected in the Missouri River at station 7.

[data; mm, millimeters]

Collection 

date

Sturgeon Paddlefish

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

Number 

collected

Mean 

length, 

in mm

Minimum 

length, 

in mm

Maximum 

length, 

in mm

5/22/2012 30 11.62 6.99 20.25 22 19.21 12 35

5/23/2012 34 11.24 6.86 17.54 15 18.75 15.68 23

5/24/2012 27 12.27 6.86 18.18 7 18.64 15.47 20
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 209

4/1 5/1 6/1 7/1 8/1 9/1 10/1 

20

40

60

80

100

120

140

160

180

200

220

0

5

10

15

20

25

30

35

5

10

15

20

25

30

35

40

Missouri River mean hourly discharge at St. Charles, Missouri

Missouri River mean hourly temperature at St. Charles, Missouri

Sturgeon free embryo or larva

EXPLANATION

Month/day

Length, in millimeters

Discharge, in one thousand cubic feet per second

Temperature, in degrees Celsius

Figure 7–2. Length of sturgeon free embryos and larvae, and mean hourly temperature and discharge from 

the U.S. Geological Survey streamgage near St. Charles, Missouri, 2012.

Month/day

04/01 05/01 06/01 07/01 08/01 09/01 10/01 

20

40

60

80

100

120

140

160

180

200

220

0

5

10

15

20

25

30

35

0

10

20

30

40

50

60

Length, in millimeters

Discharge, in one thousand cubic feet per second

Temperature, in degrees Celsius

Missouri River mean hourly discharge at St. Charles, Missouri

Missouri River mean hourly temperature at St. Charles, Missouri

Paddlefish free embryo or larva

EXPLANATION

Figure 7–3. Length of paddlefish free embryos and larvae, and mean hourly temperature and discharge 

from the U.S. Geological Survey streamgage near St. Charles, Missouri, 2012.
210 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Table 7–9. Mean density, number per 100 cubic meters, of sturgeon free embryos and larvae collected in 

the Missouri River per sampling day.

[--, no data]

Date

Station number

1 2 3 4 5 6 7

4/23/2012 -- -- -- -- 0 0 --

4/24/2012 0 0 0 0 0.13 0 --

4/25/2012 0 0 0.15 0 0 0.17 --

4/26/2012 -- 0 0.14 0 0 0 --

4/30/2012 -- -- -- 0.13 0.26 0.28 --

5/1/2012 -- 0.26 0.87 0.25 0 0.32 --

5/2/2012 0.15 0.14 0.27 0.11 0.5 0.25 --

5/3/2012 -- 0 0.11 0.44 0 -- --

5/7/2012 -- -- 0 0 0 -- --

5/8/2012 0 0.13 0 0 0.13 0.1 --

5/9/2012 0 0.12 0 0 0.09 0.09 --

5/10/2012 -- -- 0.12 0 0.11 0.48 --

5/14/2012 -- -- -- 0.14 0 0.23 --

5/15/2012 0 0 0.13 0.23 0.32 0.63 --

5/16/2012 0 0 0 0.25 0.12 0.09 --

5/17/2012 -- 0 0 0 0.31 0 --

5/21/2012 -- -- 0 0.12 0.11 0.98 --

5/22/2012 0 -- -- 0.12 0 0.96 2.45

5/23/2012 -- -- -- 0 0.06 1.68 3.22

5/24/2012 -- -- -- -- 0.11 1.65 2.45

5/29/2012 -- -- 0 0 0.37 1.52 --

5/30/2012 -- -- -- 0 0 0.55 --

5/31/2012 -- -- -- 0 0 0.45 --

6/4/2012 -- -- -- 0 0 0 --

6/5/2012 -- -- 0 0 0 0.21 --

6/6/2012 -- -- 0 0 0.07 0.25 --

6/7/2012 -- -- 0 0 0 0.76 --

6/11/2012 -- -- -- 0.12 0 0.08 --

6/12/2012 -- -- -- 0 0 0.12 --

6/13/2012 -- -- -- 0 0.06 0.35 --

6/14/2012 -- -- -- 0 0 0.2 --

6/18/2012 -- -- -- 0 0 0.19 --

6/19/2012 -- -- -- 0 0 0 --

6/20/2012 -- -- -- 0 0 0 --

6/21/2012 -- -- -- 0 0 0 --

6/25/2012 -- -- -- 0 0 0 --

6/26/2012 -- -- -- 0 0 0.05 --

6/27/2012 -- -- -- 0 0 0.12 --

7/9/2012 -- -- -- 0 0 0 --

7/10/2012 -- -- -- 0 0 0 --

7/11/2012 -- -- -- 0 0 0 --
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 211

Date

Station number

1 2 3 4 5 6 7

7/12/2012 -- -- -- 0 0 0 --

7/23/2012 -- -- -- 0 0 0 --

7/24/2012 -- -- -- 0 0 0 --

7/25/2012 -- -- -- 0 0 0 --

7/26/2012 -- -- -- 0 0 0 --

8/6/2012 -- -- -- 0 0 0 --

8/7/2012 -- -- -- 0 0 0 --

8/8/2012 -- -- -- 0 0 0 --

8/9/2012 -- -- -- 0 0 0 --

8/20/2012 -- -- -- -- 0 0 --

8/21/2012 -- -- -- 0 0 0 --

8/22/2012 -- -- -- 0 0 0.04 --

8/23/2012 -- -- -- 0 0 0 --

9/4/2012 -- -- -- 0 0 0.67 --

9/5/2012 -- -- -- 0 0 0.14 --

9/6/2012 -- -- -- 0 0 0.08 --

9/17/2012 -- -- -- 0 0 0.18 --

9/18/2012 -- -- -- 0 0 0 --

9/19/2012 -- -- -- 0 0 0 --

9/20/2012 -- -- -- -- 0 0.06 --

10/1/2012 -- -- -- -- 0 0 --

10/2/2012 -- -- -- 0 0 0 --

10/3/2012 -- -- -- 0 0 0 --

10/4/2012 -- -- -- 0 0 0 --

Table 7–9. Mean density, number per 100 cubic meters, of sturgeon free embryos and larvae collected 

in the Missouri River per sampling day.—Continued

[--, no data]
212 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Table 7–10. Mean density, number per 100 cubic meters, of paddlefish free embryos and larvae collected 

in the Missouri River per sampling day.

[--, no data]

Date

Station number

1 2 3 4 5 6 7

4/23/2012 -- -- -- -- 0.59 0.09 --

4/24/2012 0 0.14 0.28 0.33 0.4 0.17 --

4/25/2012 0.31 0 0.28 0.19 0.36 2.02 --

4/26/2012 -- 0 0.44 0.41 0.67 0.59 --

4/30/2012 -- -- -- 0.4 1.42 1.54 --

5/1/2012 -- 0.7 2.29 0.59 0.94 1.08 --

5/2/2012 1.02 0.58 0.49 0.59 0.4 0.87 --

5/3/2012 -- 0.94 0.9 0.43 1.07 -- --

5/7/2012 -- -- 0 0.11 0.18 -- --

5/8/2012 0.27 0.13 0.22 0.13 0.34 0.67 --

5/9/2012 0 0 0.11 0.11 0 0.44 --

5/10/2012 -- -- 0 0 0.19 0.77 --

5/14/2012 -- -- -- 0 0.1 0 --

5/15/2012 0.26 0.28 0 0.11 0.11 0.22 --

5/16/2012 0.25 0.15 0.16 0.11 0 0.17 --

5/17/2012 -- 0 0.16 0.12 0.12 0 --

5/21/2012 -- -- 0 0 0.22 0 --

5/22/2012 0 -- -- 0.11 0.25 0.25 2.07

5/23/2012 -- -- -- 0 0 0.51 1.33

5/24/2012 -- -- -- -- 0 0.34 0.61

5/29/2012 -- -- 0 0 0 0.45 --

5/30/2012 -- -- -- 0 0 0.4 --

5/31/2012 -- -- -- 0 0 0.38 --

6/4/2012 -- -- -- 0 0 0.11 --

6/5/2012 -- -- 0 0 0 0 --

6/6/2012 -- -- 0 0 0 0 --

6/7/2012 -- -- 0 0 0 0 --

6/11/2012 -- -- -- 0 0 0.09 --

6/12/2012 -- -- -- 0 0 0.05 --

6/13/2012 -- -- -- 0 0 0 --

6/14/2012 -- -- -- 0 0 0 --

6/18/2012 -- -- -- 0 0 0 --

6/19/2012 -- -- -- 0 0 0 --

6/20/2012 -- -- -- 0 0 0 --

6/21/2012 -- -- -- 0 0 0 --

6/25/2012 -- -- -- 0 0 0 --

6/26/2012 -- -- -- 0 0 0 --

6/27/2012 -- -- -- 0 0 0 --

7/9/2012 -- -- -- 0 0 0 --

7/10/2012 -- -- -- 0 0 0 --

7/11/2012 -- -- -- 0 0 0 --
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 213

Date

Station number

1 2 3 4 5 6 7

7/12/2012 -- -- -- 0 0 0 --

7/23/2012 -- -- -- 0 0 0 --

7/24/2012 -- -- -- 0 0 0 --

7/25/2012 -- -- -- 0 0 0 --

7/26/2012 -- -- -- 0 0 0 --

8/6/2012 -- -- -- 0 0 0 --

8/7/2012 -- -- -- 0 0 0 --

8/8/2012 -- -- -- 0 0 0 --

8/9/2012 -- -- -- 0 0 0 --

8/20/2012 -- -- -- -- 0 0 --

8/21/2012 -- -- -- 0 0 0 --

8/22/2012 -- -- -- 0 0 0 --

8/23/2012 -- -- -- 0 0 0 --

9/4/2012 -- -- -- 0 0 0 --

9/5/2012 -- -- -- 0 0 0 --

9/6/2012 -- -- -- 0 0 0 --

9/17/2012 -- -- -- 0 0 0 --

9/18/2012 -- -- -- 0 0 0 --

9/19/2012 -- -- -- 0 0 0 --

9/20/2012 -- -- -- -- 0 0 --

10/1/2012 -- -- -- -- 0 0 --

10/2/2012 -- -- -- 0 0 0 --

10/3/2012 -- -- -- 0 0 0 --

10/4/2012 -- -- -- 0 0 0 --

Table 7–10. Mean density, number per 100 cubic meters, of paddlefish free embryos and larvae 

collected in the Missouri River per sampling day.—Continued

[--, no data]
214 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

was only sampled on these 3 days because of dangerous 

sampling conditions caused by the deep, swift water of the 

thalweg. Water temperatures at the site during this time were 

about 22 °C. Excluding station 7, mean density of sturgeon 

was highest at station 6 on May 23 (1.68 sturgeon/100 m3), 

closely followed by May 24 and 29 (1.65 sturgeon/100 m3

and 1.52 sturgeon/100 m3, respectively). Water temperatures 

recorded during this time ranged from 22.3 °C to 25 °C. Mean 

density of paddlefish was more variable among sampling 

stations than mean density of sturgeon; however, the collection of paddlefish was more synchronous during the sampling 

period. The highest mean density of paddlefish was 2.29 paddlefish/100 m3

 recorded at station 3 on May 1, followed by 

2.07 paddlefish/100 m3 collected at station 7 on May 22 and 

2.02 paddlefish/100 m3 collected at station 6 on April 25 

(table 7–10). Water temperatures recorded during this time 

ranged from 15.4 °C to 22.5 °C.

In total, 338 specimens, 4 collected during preliminary 

sampling and 334 collected at seven stations, were analyzed 

for genetic species determination. Two sturgeon were unintentionally allowed to desiccate, rendering genetic analysis 

impossible. These two samples were not sent for genetic 

analysis. Results from species determination of Scaphirhynchus spp. specimens indicated that none of the 338 samples 

were pure pallid sturgeon, and 333 of the 338 samples were 

shovelnose sturgeon (p>0.95; Heist and Eichelberger, 2013). 

Analysis of the remaining five specimens was consistent with 

shovelnose sturgeon, or possibly a hybrid or backcross of 

shovelnose sturgeon with pallid sturgeon (Heist and Eichelberger, 2013). The current (2015) genetic techniques cannot 

precisely identify the exact type of hybridization (for example, 

first generation, or backcross between a hybrid and a genetically pure individual of either species) between pallid and 

shovelnose sturgeon because only subtle differences in allele 

frequencies exist, not fixed differences. These five specimens 

were collected from April 30 through June 7, 2012, at stations 6 and 7.

Summary

During 2012, most paddlefish appeared to spawn during 

April and May. Collection of free-embryo and larval specimens indicated that paddlefish spawning began earlier in 

the spring and was more synchronous than sturgeon spawning. Most sturgeon spawned from April through early June; 

however, this research also documented sturgeon spawning in 

late August and into September. One small sturgeon (7.14 millimeters total length) was collected at station 6 on September 17, 2012, when water temperature was approximately 

22.4 degrees Celsius. Size and developmental characteristics 

indicated that this sturgeon free embryo was less than 1 day 

post-hatch. These findings support earlier suggestions that 

shovelnose sturgeon in the Missouri River below Gavins Point 

Dam have a protracted spawning period (Simpkins and LaBay, 

2007).

Free-embryo and larval sturgeon were found in highest numbers and densities near and in the thalweg at stations 

6 and 7, despite the fact that station 7 was only successfully 

sampled on 3 days; therefore, it seems that many sturgeon are 

drifting in or near the thalweg where velocities are highest, 

and were likely underrepresented because of the limitations 

of sampling at station 7. This finding limits our ability to 

estimate the export of dispersing free-embryo sturgeon and 

paddlefish transported by the Missouri River. It does, however, 

seem to support the hypothesis (DeLonay and others, 2009) 

that sturgeon free embryos and larvae may drift long distances 

and may be drifting out of the Lower Missouri River into the 

Mississippi River. It has not been determined whether or not 

drift into the Mississippi River is beneficial or detrimental to 

survival. The extent to which the contemporary engineered 

channel facilitates downstream transport and enhances export 

of free embryos is an important research need.

Despite documentation of spawning by female pallid 

sturgeon (DeLonay and others, 2009; DeLonay and others, 

2010; DeLonay and others, 2012), the relative success of 

spawning in the Lower Missouri River remains unknown. To 

date, only two confirmed pallid sturgeon free embryos have 

been collected in the Yellowstone and Upper Missouri Rivers 

and none in the Lower Missouri River (Heist and Eichelberger, 

2013) suggesting that natural spawning, hatch, or both are 

severely limited. Additionally, though there is some uncertainty surrounding the exact genetic species assignment of the 

5 specimens collected during 2012 that did not strongly assign 

to either pallid or shovelnose sturgeon, the detection of these 

potential genetically-introgressed specimens may indicate 

some level of hybridization between pallid and shovelnose 

sturgeon in the Lower Missouri River.

References Cited

Bajer, P.G., and Wildhaber, M.L., 2007, Population viability 

analysis of lower Missouri River shovelnose sturgeon with 

initial application to the pallid sturgeon: Journal of Applied 

Ichthyology, v. 23, no. 4, p. 457–464. [Also available at 

http://dx.doi.org/10.1111/j.1439-0426.2007.00879.x.]

Braaten, P.J., Fuller, D.B., Holte, L.D., Lott, R.D., Viste, William, Brandt, T.F., and Legare, R.G., 2008, Drift dynamics of larval pallid sturgeon and shovelnose sturgeon in a 

natural side channel of the upper Missouri River, Montana: North American Journal of Fisheries Management, 

v. 28, no. 3, p. 808–826. [Also available at http://dx.doi.

org/10.1577/M06-285.1.]
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 215

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Simpkins, 

D.G., Wildhaber, M.L., Reuter, J.M., Bonnot, T.W., Chojnacki, K.A., Korschgen, C.E., Mestl, G.E., and Mac, M.J., 

2009, Ecological requirements of pallid sturgeon reproduction and recruitment in the lower Missouri River—A 

research synthesis 2005–08: U.S. Geological Survey OpenFile Report 2009–5201, 59 p. [Also available at http://pubs.

usgs.gov/sir/2009/5201/.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Wildhaber, 

M.L., Chojnacki, K.A., Pherigo, E.K., Bergthold, C.L., 

and Mestl, G.E., 2010, Ecological requirements of pallid 

sturgeon reproduction and recruitment in the lower Missouri 

River—Annual Report 2009: U.S. Geological Survey OpenFile Report 2010–1215, 64 p. [Also available at http://pubs.

usgs.gov/of/2010/1215/.]

DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Wildhaber, M.L., Chojnacki, K.A., Pherigo, E.K., Haas, J.D., 

and Mestl, G.E., 2012, Ecological requirements for pallid 

sturgeon reproduction and recruitment in the lower Missouri 

River—Annual report 2010: U.S. Geological Survey OpenFile Report 2012–1009, 51 p. [Also available at http://pubs.

usgs.gov/of/2012/1009/.]

Dettlaff, T.A., Ginsburg, A.S., and Schmalhausen, O.I., 1993, 

Sturgeon fishes—Developmental biology and aquaculture: 

Berlin, Springer-Verlag, 300 p.

Heist, E.J., and Eichelberger, J., 2013, 2012 genetic analysis of 

Missouri River sturgeon larvae: Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University 

Carbondale, 27 p. 

Humphries, Paul, Serafini, L.G., and King, A.J., 2002, River 

regulation and fish larvae—Variation through space and 

time: Freshwater Biology, v. 47, no. 7, p. 1307–1331. 

[Also available at http://dx.doi.org/10.1046/j.1365-

2427.2002.00871.x.]

Kynard, B., Parker, E., Pugh, D., and Parker, T., 2007, Use of 

laboratory studies to develop a dispersal model for Missouri 

River pallid sturgeon early life intervals: Journal of Applied 

Ichthyology, v. 23, p. 365–374. [Also available at http://

dx.doi.org/10.1111/j.1439-0426.2007.00908.x.]

Reuter, J.M., Jacobson, R.B., Elliott, C.M., and DeLonay, A.J., 

2009, Assessment of lower Missouri River physical aquatic 

habitat and its use by adult sturgeon (genus Scaphirhynchus) 2005–07: U.S. Geological Survey Scientific Investigations Report 2009–5121, 81 p. [Also available at http://

pubs.er.usgs.gov/usgspubs/sir/sir20095121.]

Scheidegger, K.J., and Bain, M.B., 1995, Larval fish distribution and microhabitat use in free-flowing and regulated rivers: American Society of Ichthyologists and Herpetologists, 

Copeia, v. 1995, no. 1, p. 125–135. [Also available at http://

www.jstor.org/stable/1446807.]

Simpkins, D.G., and LaBay, S.R., 2007, Site-specific assessment of spawning behavior and habitat use, in Korschgen, 

C., ed., Factors affecting the reproduction, recruitment, 

habitat, and population dynamics of pallid sturgeon and 

shovelnose sturgeon in the Missouri River: U.S. Geological 

Survey Open-File Report 2007–1262, p. 217–254. [Also 

available at http://pubs.usgs.gov/of/2007/1262/pdf/OF2007-

1262.pdf.]

Steffensen, K.D., Pegg, M.A., and Mestl, G., 2013, Population 

prediction and viability model for pallid sturgeon (Scaphirhynchus albus, Forbes and Richardson, 1905) in the lower 

Missouri River: Journal of Applied Ichthyology, v. 29, no. 

5, p. 984–989. [Also available at http://dx.doi.org/10.1111/

jai.12277.]

U.S. Fish and Wildlife Service, 2007, Pallid sturgeon (Scaphirhynchus albus) 5-year review—Summary and evaluation: 

Billings, Mont., U.S. Fish and Wildlife Service, 120 p. 

Wildhaber, M.L., DeLonay, A.J., Papoulias, D.M., Galat, D.L., 

Jacobson, R.B., Simpkins, D.G., Braaten, P.J., Korschgen, 

C.E., and Mac, M.J., 2007, A conceptual life-history model 

for pallid and shovelnose sturgeon: U.S. Geological Survey 

Circular 1315, 18 p. [Also available at http://pubs.usgs.gov/

circ/2007/1315/.]

Wildhaber, M.L., DeLonay, A.J., Papoulias, D.M., Galat, D.L., 

Jacobson, R.B., Simpkins, D.G., Braaten, P.J., Korschgen, 

C.E., and Mac, M.J., 2011, Identifying structural elements 

needed for development of a predictive life-history model 

for pallid and shovelnose sturgeons: Journal of Applied Ichthyology, v. 27, no. 2, p. 462–469. [Also available at http://

dx.doi.org/10.1111/j.1439-0426.2011.01731.x.]
216 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

Appendix 8. Influence of Channel Morphology and Flow Regime on FreeEmbryo Drift of Pallid Sturgeon in the Lower Missouri River

River, measurement sites were selected from the Gavins Point, 

Ponca, Big Sioux, Kansas, and Grand segments. Dispersion 

coefficients are highly sensitive to variations in discharge, and 

discharge varies substantially along the length of the Lower 

Missouri River; thus, to facilitate comparison of values among 

measurement sites, datasets used were limited in this analysis 

to those collected when discharge was within a limited range 

of flow exceedance values (64–82 percent exceedance) as 

measured at the U.S. Geological Survey (USGS) streamgage 

location nearest each measurement site for the period of regulated flows, 1967–2012 (Galat and Lipkin, 2000) (table 8–1). 

All data selected for use in the present (2015) analysis were 

collected in 2005, 2006, or 2007. Although more recent ADCP 

data have been collected on the Lower Missouri River, the 

largest availability of data were collected in numerous segments at comparable flow exceedances for the period from 

2005 to 2007. Analysis was limited to datasets where most 

cross-sections fully spanned the wetted channel and transects 

contained limited missing ensembles. Additionally, datasets 

surveyed in bends with high curvature were excluded since 

theoretical determination of DL is less accurate at sites where 

patterns of secondary circulation dominate the flow field. All 

velocity measurements were done using a Rio Grande ADCP 

(Teledyne RD Instruments, Poway, California). Data were 

originally reported by Reuter and others (2009).

Dispersion coefficients were calculated using AdcpXP, a 

software package developed at the University of Iowa Department of Hydroscience and Engineering for post-processing 

ADCP data (www.iihr.uiowa.edu/research/pulications-andmedia/adcpxp-software-release-ii/). The DL was determined 

for each cross-section, using the one-dimensional equation for 

the longitudinal dispersion coefficient (Fischer, 1973):

 (1)

where

A is cross-sectional area,

B is channel width,

y is the cross-stream coordinate,

h is depth, and

Dy is the transverse mixing coefficient.

The depth-averaged velocity deviation from the mean 

cross-sectional velocity is:

 (2)

where

u′(y) is the mean cross-sectional velocity,

u(y) is the depth-averaged streamwise velocity, 

and

is the cross-sectionally-averaged streamwise 

velocity.

Background

Downstream transport of a constituent, or passively 

drifting organisms, is a function of mean channel velocity 

(advection) and hydraulic factors that tend to distribute particles longitudinally around the center of mass of the particles 

(dispersion). Particle transport is typically mathematically 

expressed using the one-dimensional advection-dispersion 

equation (Fischer, 1973), in which the strength of the longitudinal dispersion is quantified by the longitudinal dispersion 

coefficient (henceforth referred to as the dispersion coefficient 

[DL]). Traditionally, DL has been estimated by direct measurement from tracer studies (Yotsukura and others, 1970) or 

calculated using empirical relations (Jobson, 1996); however, 

tracer experiments are costly endeavors, yielding results that 

apply to a limited range of flow conditions, and empirical 

relations may only provide accuracy to within an order of 

magnitude. Recent advances in instrumentation that allow for 

the rapid collection of stream velocity and bathymetric data 

have facilitated an alternative approach, in which estimates of 

DL

 may be derived directly from the theory of shear dispersion 

and velocity data (Carr and Rehmann, 2007; Kim, 2012).

Correctly estimating DL is critical to accurately predicting the longitudinal distribution of particles in transport; 

however, dispersion coefficients also may be used as a metric 

to evaluate the relative retention capacity of geomorphically 

distinct sections of river. Higher values of the coefficient suggest a greater retentive potential at a given cross-section, thus 

increasing dispersion in the along-stream direction.

Scope and Objectives

To explore the effects of flow regime and channel morphology on drift of free-embryo pallid sturgeon (Scaphirhynchus albus), DL

 was calculated for several velocity measurement sites along the Lower Missouri River. Additionally, reach 

average values of DL were used to model drift at documented 

spawning sites to provide a first-order estimation of cumulative drift distances along the Lower Missouri River.

Methods

Dispersion coefficients were calculated using velocity data collected by an acoustic Doppler current profiler 

(ADCP) in 11 reaches on the Lower Missouri River (fig. 8–1, 

table 8–1). Calculations were made using existing ADCP data 

and selection of data was determined by the following factors: 

(1) river mile, (2) discharge, (3) data quality and continuity, (4) the number of transects contained within the dataset, 

and (5) channel curvature. Because the goal was to quantify 

longitudinal patterns in dispersion in the Lower Missouri 

D

A u y h y dy D h y

dy u y h y dy L

B y

y

y

= − () () ( ) ′ ( )( ) ′ ′ ′′ ′′ ∫ ∫ ∫ 1 1

0 0 0

' ''

'

u y ′( ) = u y( )−U

U
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 217

Map area

Missouri Rive rMissouri Rive r

Sioux City (6486000)

Waverly

(6895500)

Nebraska City (6807000)

Decatur 

(6601200)

St. Joseph

(6818000)

Hermann

(6934500)

St. Charles 

(6935965)

Boonville 

(6909000)

Kansas City

(6893000)

Rulo (6813500)

Glasgow 

(6906500)

Platte River (6805500)

Kansas River

(6892350)

Omaha (6610000) Boundary of 

Missouri River Basin

Minimally engineered

section

River segment

Gavins Point

Ponca

Big Sioux

Platte

Kansas

Grand

Osage

EXPLANATION

Velocity measurement site

U.S. Geological Survey streamgage

 with name and number

Boonville 

(6909000)

96° 94° 92° 90°

40°

42°

IOWA

MISSOURI

NEBRASKA

KANSAS

WISCONSIN

 ILLINOIS

Base data from National Atlas digital data, 2006

Universal Transverse Mercator projection

Zone 15

Waterbody data from U.S. Geological Survey

National Hydrography Dataset, 2006

0

0

25

25

50 MILES

50 KILOMETERS

Missouri River

Missouri River

Figure 8–1. Missouri River segments, U.S. Geological Survey streamgages, and velocity measurement sites used for calculation 

of longitudinal dispersion coefficients.
218 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

In AdcpXP, the transverse mixing coefficient is defined 

as:

 (3)

where

u* is shear velocity.

Shear velocity is calculated using a reach-scale estimate:

(4)

where

g is gravity,

R is hydraulic radius, and

S is water surface slope (Kim, 2012).

A constant S of 2.0x10-4 was inputted based on estimates 

of the slope of the 75 percent exceedance water surface elevation, also known as the Missouri River Construction Reference 

Plane (CRP) (U.S. Army Corps of Engineers, unpub. data). 

The variation in DL resulting from variations in slope within 

the range of values reported for the Lower Missouri River is 

small relative to the variation in DL resulting from variability 

in the flow field.

When calculating dispersion coefficients using the 

theoretical framework developed by Fischer (1973) based on 

ADCP data, it must be ensured DL reflects deviations of depthaveraged velocities from the mean cross-sectional velocity, not 

the small-scale turbulence-induced fluctuations in velocity; 

thus, calculations of DL were compared based on single transects and multiple reciprocal transects (pairs of transects surveyed across the current in opposing directions) at select sites. 

The difference among values from multiple passes at a given 

transect and the average of those values is small compared 

to the variability observed between one transect and another; 

thus, because our calculations of longitudinal dispersion 

coefficients were insensitive to averaging reciprocal transects 

and there was very limited data where repeat velocity transects 

were collected at the same cross-section, single transects were 

used to calculate DL in this analysis.

Drift of free embryos for two sites were modeled where 

spawning has been documented on the Lower Missouri River. 

Total drift distances were calculated using the one-dimensional 

advection-dispersion equation (Fischer, 1973):

 (5)

where

C is concentration of free embryos,

M is the number of free embryos released,

t is time post-release, and

x is distance downstream.

The first drift simulation is for a spawning event that 

began on April 28, 2010, at about river mile (RM) 634. The 

second spawning event considered began on May 17, 2011, at 

RM 216. In each simulation the median DL value determined 

at the site nearest the spawning location was used (RM 640 for 

the 2010 spawning event and RM 202 for the 2011 spawning 

event). Mean cross-sectional velocity was determined from the 

nearest USGS streamgage on the initial day of spawning and 

treated as a constant.

Interpretation of advection-dispersion model results 

must be considered in light of several important assumptions. 

First, the approach assumes that drift is entirely passive, an 

assumption challenged by empirical data that suggest that free 

embryos drift downstream at a rate slightly slower than the 

mean channel velocity and tend to seek the bottom (Braaten 

and others, 2012). It is unknown, however, the degree to 

which drifting free embryos exert control over position in the 

water column and cross-section in such a swift and turbulent 

Table 8–1. Characteristics of Missouri River sites used to obtain data for estimating dispersion coefficients.

[m3/s, cubic meter per second]

Measured 

site 

number

Segment River 

mile Date

Mean daily 

discharge 

(m3

/s)

Closest streamgage Streamgage 

river mile

Flow 

exceedance,

in percent 

Number of 

transects 

used

1 Gavins 799 22 May, 2007 702 Sioux City, Iowa 732 69 21

2 Gavins 797 1 June, 2007 637 Sioux City, Iowa 732 74 12

3 Ponca 745 25 May, 2007 646 Sioux City, Iowa 732 74 26

4 Big Sioux 707 13 June, 2007 733 Sioux City, Iowa 732 66 90

5 Big Sioux 640 16 June, 2007 858 Omaha, Nebraska 616 64 87

6 Kansas 332 20 June, 2006 1,008 Kansas City, Missouri 366 79 73

7 Kansas 328 24 May, 2006 1,093 Kansas City, Missouri 366 73 75

8 Kansas 278 14 June, 2006 1,059 Waverly, Missouri 293 64 54

9 Grand 202 6 June, 2006 1,135 Boonville, Missouri 197 78 60

10 Grand 196 7 June, 2006 1,076 Boonville, Missouri 197 82 78

11 Grand 162 10 May, 2005 1,147 Boonville, Missouri 197 78 70

D u h y = 0 6. *

u gRS * .= ( )0 5

C M

A D t

e

L

x Ut

D t = L

























− − ( )

2

2

4

p
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 219

environment as the Lower Missouri River. Second, the model 

used here is one-dimensional; thus, although calculation of 

the DL reflects the cross-stream variability in velocity, the 

approach greatly simplifies the effects of hydraulic heterogeneity on dispersion and drift. Third, input parameters for 

each site were taken from the location where spawning was 

documented; therefore, the simulations do not account for 

longitudinal variation in model inputs, such as velocity and 

DL; consequently, because velocity steadily increases in the 

downstream direction, calculations may represent a conservative estimate of total downstream transport.

Despite these assumptions, the model results provide a 

valuable first-order estimate of total drift distance along the 

Lower Missouri River. The analysis provides a more robust 

approach for calculating total drift distance than simple 

estimates of total travel distance based on mean velocity 

because it explicitly accounts for dispersion of free embryos 

along a longitudinal gradient; moreover, incorporation of the 

dispersion coefficient into the model allows exploration of the 

effects of varying channel morphology on downstream transport of drifting free embryos.

Results

Median values of DL range from about 100 meters 

squared per second (m2/s) in a reach of the Big Sioux segment to greater than (>) 2,000 m2

/s in one reach within the 

Grand segment (table 8–2). Within each reach, there is a 

large range in calculated values of DL

 (fig. 8–2), reflecting 

the within-reach hydraulic variability induced by variations 

in engineering structures and channel form. The interquartile 

range (IQR) of DL among measured reaches was 109 m2/s to 

2,629 m2/s.

Values of DL vary longitudinally (table 8–2). The highest 

values of DL are in the Kansas and Grand segments where the 

median values range from 866 to 2,206 m2/s. The Kansas and 

Grand segments also contain the greatest variability in calculated values of DL

. The IQR within these reaches ranges from 

1,330 to 2,629 m2/s. The lowest median values and the lowest 

IQR are in the Big Sioux segment. The two reaches in the Big 

Sioux segment have median values of 102 and 137 m2/s, and 

IQR of 327 and 109 m2/s. The measurement reach within the 

Ponca segment also has a low median value (DL=163 m2/s). 

Dispersion coefficients in the Gavins segment fall in between 

the high values calculated for the downstream Lower Missouri 

River and the low values in the Big Sioux segment farther 

upstream. The median DL

 in the two measurement reaches 

within the Gavins segment were 1,154 and 445 m2/s.

Dispersion coefficients reported compare favorably 

to estimates of DL determined from tracer studies done in 

a 227-kilometer (km) (141-mile [mi]) reach of the Lower 

Missouri River between Sioux City, Iowa, and Plattsmouth, 

Nebraska (Yotsukura and others, 1970). At the time of 

the tracer experiment, discharge at the measurement sites 

ranged from about 880 to 980 cubic meters per second (m3/s) 

(31,200–34,500 cubic feet per second [ft3/s]), and the calculated dispersion coefficients ranged from 690 to 2,472 m2

/s, 

797799 328332 278 202 162196

Dispersion coefficient, in square meters per second

640707745

Gavins Grand

River mile

Ponca Sioux Kansas

100,000

10

100

1,000

10,000

1

50th percentile (median)

25th percentile

EXPLANATION

10th percentile

Individual observation below 

10th percentile

Individual observation above 

90th percentile

90th percentile

75th percentile

Fgure 8–2. Dispersion coefficients calculated for velocity measurement sites along the Lower Missouri River.
220 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

depending on the length of river over which the tracer 

data were integrated. Yotsukura and others (1970) determined the most representative DL

 value to be approximately 

1,487 m2/s. This value is higher than the DL determined in 

this study at the ADCP measurement site upstream from 

Omaha (RM 640) where ADCP data were collected in 2007 

(median DL=102 m2/s); however, the tracer experiments were 

completed 40 years before the ADCP data, during which 

time the morphology of the Missouri River has continued to 

evolve (Jacobson and others, 2009; Pinter and others, 2010; 

U.S. Army Corps of Engineers, 2012). It is not exactly clear 

how DL values would necessarily have been affected by 

the morphologic trends through time, but it is possible that 

ongoing deposition on channel margins and in dike pools has 

resulted in diminished flow complexity and lower DL values. 

The results of the tracer experiment indicate that high values 

of DL calculated using the theoretical approach employed are 

within the range of expected values for a river the size of the 

Lower Missouri River.

Simulations of drift done using the one-dimensional 

advection-dispersion model indicate that pallid sturgeon free 

embryos that originated at spawning locations in the Lower 

Missouri River may drift into the Mississippi River before 

they begin exogenous feeding. Drift distances modeled for the 

May 17, 2011, spawning event, which happened near RM 216 

in the Grand segment, show that at 3 days post-hatch (dph) 

most free embryos would have been advected downstream 

into the Mississippi River (fig. 8–3). Modeled drift distances 

for April 28, 2010, when spawning originated much farther 

upstream at RM 634 in the Big Sioux segment, suggest that 

most drifting free embryos may remain in the Missouri River 

through 9 dph; however, the model results suggest that by 

11 dph, most of the drifting free embryos would have been 

exported into the Middle Mississippi River.

Estimates of drift distance and dispersion are sensitive to 

DL

, with larger values of DL resulting in a greater longitudinal 

spread of the distribution (fig. 8–4). Although downstream 

advection is determined by mean cross-sectional velocity and 

the central tendency of the distribution remains unchanged 

with varying DL, channel morphology that promotes dispersion and retention of drifting particles may have significant 

implications on retention of drifting free embryos within the 

Lower Missouri River. For example, in the simulation of drift 

for the April 28, 2010, spawning event, a shift towards a longtailed longitudinal distribution of drifting free embryos would 

substantially increase the proportion of pallid sturgeon remaining in the Missouri River System at 11 dph.

Interpretation of Longitudinal Dispersion 

Coefficients

The wide range in calculated values for DL at each 

measurement site reflects the within-reach heterogeneity in 

channel morphology and hydraulic patterns. Transects where 

the channel and flow field are more uniform have low values 

of DL, whereas flow transects with more variable channel 

morphology have a more pronounced transverse velocity 

gradient and thus higher values of DL. The assumption underlying equation (1) that flow is one-dimensional may limit the 

validity of the equation where strong patterns of secondary 

circulation exist, such as in tightly curved bends or in the 

protected zone in between wing dikes (Carr and Rehmann, 

2007). Nonetheless, the equation does accurately reflect the 

physical reality that at transects where there is a pronounced 

transverse velocity shear, the local hydraulic conditions promote greater retention and longitudinal dispersion of drifting 

free embryos.

Table 8–2. Descriptive statistics for longitudinal dispersion coefficient calculated for each measurement site in the Missouri River.

[DL, dispersion coeffiecient; m2/s; square meter per second]

Measured 

site 

number

Segment River 

mile Date Mean DL

 (m2/s)

Standard deviation

DL (m2/s)

1st quartile 

(m2/s)

Median 

DL (m2/s)

3rd quartile 

(m2/s)

1 Gavins 799 22 May, 2007 1,353 1,062 453 1,154 1,898

2 Gavins 797 1 June, 2007 562 410 245 445 860

3 Ponca 745 25 May, 2007 470 639 69 163 798

4 Big Sioux 707 13 June, 2007 317 422 70 137 397

5 Big Sioux 640 16 June, 2007 142 146 60 102 169

6 Kansas 332 20 June, 2006 1,921 2,642 616 1,227 1,946

7 Kansas 328 24 May, 2006 2,404 3,319 384 1,242 3,013

8 Kansas 278 14 June, 2006 1,769 1,929 342 866 2,726

9 Grand 202 6 June, 2006 1,503 1,469 459 938 2,125

10 Grand 196 7 June, 2006 2,333 2,050 1,003 1,954 3,023

11 Grand 162 10 May, 2005 3,110 2,909 1,390 2,206 3,532
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 221

In addition to the intra-reach variability, inter-reach differences in the DL

 highlight the distinct geomorphic characteristics and styles of channel engineering employed in 

different segments of the Lower Missouri River. The channel 

immediately downstream from Gavins Point Dam is the least 

engineered section of the Lower Missouri River. The channel within the Gavins segment is multithreaded, containing 

numerous bars, islands, and side channels, which are features 

that promote hydraulic variability across a range of discharges. 

Farther downstream, in the Ponca segment, values of DL 

decrease compared to those of the Gavins segment, reflecting 

the reduced morphologic and hydraulic heterogeneity. Downstream from Sioux City, in the Big Sioux segment, channel 

morphology changes dramatically because of channelization 

by wing dikes and bank revetment. The effects of conversion 

of the channel to a single-threaded, self-scouring navigation 

channel are apparent in the values of DL. Dispersion coefficients within the Big Sioux segment are the lowest calculated 

in this analysis. Additionally, the Big Sioux reach has the 

smallest spread in the data.

Interestingly, both the highest median values of DL and 

the greatest intra-reach variability in DL are in the downstream 

Lower Missouri River. The values of DL calculated for the 

Kansas and Grand segments reflect the abrupt change in the 

style of channel engineering near Rulo, Nebraska, as described 

in the section of this report titled, “Missouri River Management Context.” Within the downstream Lower Missouri 

River, large dikes generate pronounced zones of recirculation 

and strong cross-stream velocity gradients, resulting in high 

dispersion coefficients. In reality, these zones of recirculation, or “dead zones”, create zones of transient storage for 

constituents in transport and the true effects of these features 

cannot be captured in a one-dimensional model. The exchange 

rate between the main channel and dead zones associated with 

dikes is controlled by factors such as dike geometry, inclination, flow depth, and turbulent intensity in both the main channel and zone of recirculation. These unique physical attributes 

interact to determine the complex patterns of recirculation 

within the dead zone and the hydraulics of the shear zone at 

the boundary between the main channel and dead zone. In 

general, these zones of transient storage increase retention and 

retard mean transport velocity (Jirka and Weitbrecht, 2005).

It is important to emphasize that data used in this analysis 

were collected during a limited range of flows, and DL

 is 

highly sensitive to discharge. Calculation of DL for transects where velocity data have been collected over a range 

of discharges demonstrates that site-specific morphologic 

characteristics strongly influence the effects of changes in 

discharge of dispersive potential (fig. 8–5A); for example, near 

RM 197, ADCP data were collected at three discharges (1,218, 

2,571, and 6,089 m3/s, or 43,000, 90,800, and 215,000 ft3/s). 

As discharge increases, but dikes remain emergent, DL

increases because of the stronger transverse velocity gradient 

(fig. 8–5B); however, when flow overtops the dikes, there is a 

decrease in DL because cross-stream flow becomes more uniform and there is a reduction in the relative transverse velocity 

A. Drift simulation for May 17, 2011, spawning location

River mile (RM)

800 600 400 200 0 -200 -400

Concentration, in arbitrary units Concentration, in arbitrary units

B. Drift simulation for April 28, 2010, spawning location

Mississippi River

confluence 

3 days post-hatch (dph)

5 dph

7 dph

River mile (RM)

800 600 400 200 0 -200 -400

3 dph

5 dph

7 dph 9 dph 11 dph 13 dph

Spawning

location

(RM 216)

Spawning

location

(RM 634)

Mississippi River

confluence 

Figure 8–3. Downstream transport and dispersion of passively 

drifting free embryos using the one-dimensional advectiondispersion equation. A, drift simulation for May 17, 2011, spawning 

location at 3, 5, and 7 days post-hatch; and B, drift simulation for 

April 28, 2010, spawning location at 3, 5, 7, 9, 11, and 13 days posthatch.

EXPLANATION

Distance downstream from arbitrary release point, in kilometers

Arbitrary concentration

0 500 1,000 1,500 2,000

0

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

25th percentile

50th percentile

75th percentile

1 day post-hatch (dph)

3 dph

5 dph

7 dph

9 dph 11 dph 13 dph

Dispersion coefficient

Figure 8–4. Relation between free embryo downstream drift 

distance and concentration of free embryos released at an 

arbitrary upstream point.
222 Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Missouri River—2005 to 2012

shear. In contrast, near RM 177, where ADCP data were 

collected over a similar range of discharges (1,529, 2,373, and 

6,004 m3/s, or 54,000, 83,800, and 212,000 ft3/s), the trend is 

quite different (fig. 8–5). Dispersion coefficients remain low 

at a range of low discharges because flow is confined to the 

navigation channel along the right bank of the river. Inundation of the sand bar along river left substantially increases the 

transverse velocity gradient and provides a zone of elevated 

retention, which is reflected in higher values of DL. Analyses 

at these two sites highlight the sensitivity of DL to discharge, 

but more importantly highlight the site-specific interactions 

of local morphology, engineered structures, and hydraulics 

that combine to determine patterns in dispersion of drifting 

particles.

Implications for River Management

Complex interactions of discharge, hydraulics, and 

channel morphology determine drift and dispersion of free 

embryos. Flow regime affects drift in two distinct ways: (1) 

discharge and mean velocity control the advection, or downstream transport, of free embryos; and (2) changes in flow 

regime alter channel hydraulics, which affect the dispersion 

and retention of free embryos; thus, although higher flows 

would increase downstream advection of drifting pallid 

sturgeon free embryos, flow pulses also have the potential to 

increase dispersion of drifting free embryos, spreading them 

out more along a longitudinal gradient. 

Retention of pallid sturgeon free embryos is influenced 

by the availability of littoral shallow water habitat, which has 

been substantially reduced throughout the Missouri River 

Basin by flow regulation and channel alterations (Bowen and 

others, 2003; Jacobson and Galat, 2006); however, although 

total area of shallow water habitat is substantially less than 

would have occurred in the absence of channel alterations, 

high flows have the potential to increase retention of free 

embryos by inundating low-lying alluvial surfaces within 

the active channel, secondary channels, and vegetated riparian habitats in the channel margins as may exist in natural or 

restored reaches of the river. The reduced flow velocities and 

high roughness values characteristic of these environments 

increase hydraulic gradients, thus promoting retention of drifting free embryos. Studies using theoretical models (Wallis and 

Manson, 2005) indicate that dispersion coefficients steadily 

increase with discharge in simplified channels, reaching a 

maximum when flow has just overtopped the channel banks 

and inundated the floodplain; thus, flow regime modifications have the potential to substantially influence patterns of 

retention and dispersion of drifting free embryos by altering how flow interacts with various channel and floodplain 

environments.

The effects of flow regime on dispersion of free embryos 

are tightly coupled to channel morphology. A spring flow pulse 

may affect dispersal of free embryos in very different ways 

in different parts of the Missouri River, reflecting the unique 

interaction of discharge, channel engineering, and hydraulics; 

for example, Jacobson and Galat (2006) demonstrated that in 

channelized reaches of the river that display reduced morphologic and hydraulic complexity, increases in discharge result 

in no increase in total area of shallow water habitat until the 

channel overtops its banks. In contrast, hydrodynamic models 

of flow through reconstructed topography for the unchannelized river demonstrate that total shallow water habitat would 

have steadily increased with discharge as low elevation alluvial surfaces were gradually inundated. The implications of 

this analysis for drift of free embryos is that in segments of the 

Lower Missouri River with minimal channel engineering, such 

as the segment downstream from Gavins Point Dam, changes 

in flow regime have greater potential to increase retention of 

larval sturgeon than in reaches where hydraulic variability is 

less sensitive to discharge, such as the Big Sioux segment of 

the river.

Present (2015) understanding of the potential for channel engineering to retain and grow free embryos to the larval 

stages is based on the concept of shallow water habitat, which 

defines a volume of habitat but fails to address the processes 

that lead to exchange between the main channel and marginal 

habitats. Improved understanding of the details of hydraulics 

Discharge, in cubic meters per second

0 1,000 2,000 3,000 4,000 5,000 7,000

Longitudinal dispersion coefficient,

in square meters per second

Longitudinal dispersion coefficient,

in square meters per second

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

0

5,000

10,000

15,000

20,000

25,000

30,000

Large sand bar 

on river left 

innundated

Large sand bar 

on river left 

exposed at 

discharge

A. Change in dispersion coefficient with discharge near river mile 197

B. Change in dispersion coefficient with discharge near river mile 177

Dikes emergent 

at specified 

discharge

Dikes submerged

6,000

Discharge, in cubic meters per second

1,000 2,000 3,000 4,000 5,000 6,000 7,000

Figure 8–5. Change in the longitudinal dispersion coefficient 

with discharge. A, river mile 197 and B, river mile 177.
Comprehensive Sturgeon Research Project, Annual Report 2012, Appendixes 1–8 223

at scales ranging from individual wing dikes to bends of rivers, combined with intensive sampling of free embryos and 

larvae, will be needed to establish how channel engineering 

and flow regime may be optimized to retain early life-stage 

pallid sturgeon in supportive habitats.

Summary

The distinct geomorphic characteristics and styles of 

channel engineering employed in different segments of the 

Lower Missouri River are manifested in longitudinal dispersion coefficients calculated from acoustic Doppler current 

profiler data. The lowest values of the longitudinal dispersion 

coefficient are found in the Ponca and Big Sioux segments 

where the flow field is homogeneous. Increased topographic 

and hydraulic complexity within the Gavins segment translates into higher dispersion coefficients, reflecting the greater 

potential for retention of drifting free embryos within this 

reach. Although the Kansas and Grand segments are highly 

engineered, these sections of river have the highest dispersion 

coefficients because large dikes generate pronounced zones of 

recirculation and strong transverse velocity shear.

Drift simulations completed using the one-dimensional 

advection-dispersion equation suggest that most passively 

drifting free embryos are exported from the Lower Missouri 

River into the Middle Mississippi River. The analysis assumes 

drift is entirely passive, an assumption which is contested by 

limited field data, and this one-dimensional approach neglects 

the effects of zones of transient storage on retention of drifting 

free embryos. Nonetheless, the model results provide a valuable estimate of total drift distance along the Lower Missouri 

River, and the analysis highlights the complex local interactions of channel morphology, engineering, and flow regime 

that control retention and drift of free embryos. 

References Cited

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of channel modification on fish habitat in the upper Yellowstone River—Final report to the USACE, Omaha: 

U.S. Geological Survey Open-File Report 2003–476, 30 p.

Braaten, P.J., Fuller, D.B., Lott, R.D., Ruggles, M.P., Brandt, 

T.F., Legare, R.G, and Holm, R.J., 2012, An experimental 

test and models of drift and dispersal processes of pallid 

sturgeon (Scaphirhynchus albus) free embryos in the Missouri River: Environmental Biology of Fishes, v. 93, no. 3, 

p. 377–392. [Also available at http://dx.doi.org/10.1007/

s10641-011-9925-9.]

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mixing in open-channel flow: Annual Review of Fluid 

Mechanics, v. 5, no. 1, p. 59–78.

Galat, D.L., and Lipkin, Robin, 2000, Restoring ecological integrity of great rivers—Historical hydrographs aid 

in defining reference conditions for the Missouri River: 

Hydrobiologia, v. 422–423, p. 29–48.

Jacobson, R.B., and Galat, D.L., 2006, Flow and form in 

rehabilitation of large-river ecosystems—An example from 

the lower Missouri River: Geomorphology, v. 77, no. 3–4, 

p. 249–269.

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