INFLUENCE OF WING DAM NOTCHING ON FISH, AQUATIC MACROINVERTEBRATES, HYDROGRAPHIC RELIEF, CURRENT VELOCITY, SUBSTRATE, WATER TEMPERATURE, AND DISSOLVED OXYGEN IN POOL 13, UPPER MISSISSIPPI RIVER

by

Scott D. Corley Wisconsin Cooperative Fishery Research Unit

A Thesis submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE

College of Natural Resources

UNIVERSITY OF WISCONSIN Stevens Point, Wisconsin

May 1982 Approved by the Graduate Committee of:

Dr. Daniel W. Coble, Committee Chairman Professor of Fisheries

Dr. Frederick A. Copes Professor of Biology

Dr. Stanley W. Szczytko Professor of Water Science

i i ABSTRACT

Six wing dams and an adjacent side channel in Pool 13 of the upper Mississippi River were studied in 1978-1980 to determine effects of wing dam notching on fish, aquatic macroinvertebrates, hydrographic relief, current velocity, substrate, water temperature, and dissolved oxygen. Three wing dams were notched in May-July 1979. Water temperature and dissolved oxygen concentration did not appear to be affected by notching. No major changes in the configuration of river bottom adjacent to the wing dams or in the side channel were detected after notching, but changes in the structure of wing dams caused by notching and repair were evident. Current velocity increased significantly below notches. An increase in the proportion of sand in the substrate of the side channel appeared to be related to notching, but a general, significant increase in benthos populations in the main channel border (near wing dams) from the prenotching to postnotching period probably was not related to notching. Rather this increase was probably due to a severe reduction of Chironomidae (Diptera) and Potamyia flava (Hagen) (Trichoptera: Hydropsychi.dae) populations by unusually high discharge in July 1978 {prenotching period) and their subsequent recovery in postnotching 1979 and 1980. Benthos did not increase significantly in the side channel after notching probably because of the increase in sand which appeared to be caused by notching. High gravel content in the substrate and high benthic invertebrate densities below the notch in wing dam 26 in the fall of 1979 were probably a localized effect of increased flow caused by notching. Artificial substrates on the

iii wing dams were colonized much more heavily than the predominantly sand river bed, which was sampled with a Ponar grab. A detrimental effect of notching may be the removal of productive substrate (wing dam rock) for aquatic organisms. There were no appreciable effects of notching on fish populations. The increased proportion of sand in the substrate of the side channel during the postnotching period may indicate the occurrence of a long-term increase in sediment deposition in the side channel, shortening its life. The predominantly submerged character of the wing dams in the study area may be more important than notching in reducing accretion of sediments between the dams and in the side channel.

iv ACKNOWLEDGEMENTS

This study was supported by funds and materials from the Great River Environmental Action Team II and the Wisconsin Cooperative Fishery Research Unit, University of Wisconsin, Stevens Point. I would like to thank my colleagues, Tom Hall, Rod Pierce, and Dr. William LeGrande, for their guidance and assistance in the field and the laboratory. I am also grateful to John Pitlo, Mark Anderson, and Dean Beck of the Iowa Conservation Commission for their cooperation and assistance. Thanks go to Ed Bowles, Tim Copes, Steve Kirking, Sue Littlejohn, Jim Marchuk, and the numerous other students who spent many hours in the field and laboratory collecting data and processing samples. I am indebted to my advisor, Dr. Daniel W. Coble, for his advice, supervision, and critical evaluation of the manuscript. I am also grateful to Dr. Fred Copes for examining the manuscript, Dr. Stan Szczytko for confirming insect identification and examining the manuscript, Dr. Earl Spangenberg for advice concerning substrate ana·lysis, Dr. Edward Stern for confirming bivalve mollusk identification, and to Dr. Fred Hilpert, Tom Zeisler, and Bruce Repplinger for help with statistical procedures and computer programming.

I dedicate this thesis to my parents, Robert and ~1arianne Corley, for their love and support throughout all of my endeavors.

v TABLE OF CONTENTS Page TITLE PAGE ------i COMMITTEE SIGNATURE PAGE ------ii ABSTRACT ------iii ACKNOWLEDGEMENTS ------v TABLE OF CONTENTS ------vi LIST OF TABLES ------viii LIST OF FIGURES ------x LIST OF APPENDICES ------xii

CONCLUSIONS ------~------1 INTRODUCTION ------3 STUDY AREA ------6

METHODS ------~------10

Sampling and Sample Processing ------~- 10 Discharge and Staff Gauge ------10 Hydrographic Relief ------10 Hydrographic Relief and Benthos Sampling Sites ----- 11

Physicochemical Characteristics ------16 Aquatic Macroinvertebrates ------17

Fish ------~------20 Statistical Analyses ------27 Current Velocity ------27 Substrate ------31 Benthos ------31 Fish ------33

vi Page RESULTS AND DISCUSSION ------39 Hydrographic Relief ------39

Disch~rge ------40 Current Velocity ------40 Substrate ------46

Temperature and Dissolved Oxygen ---~------51

Benthos ------54

Abundance and Species Diversity ------~---- 54

Taxonomic Composition ------65 Macroinvertebrate Aufwuchs ------68 Fish ------71

LITERATURE CITED ------~---- 81

APPENDICES ------~--- 88

vii LIST OF TABLES Page Table 1. Locations of artificial substrate transects (meters from Illinois bank), Pool 13, upper Mississippi River (refer to Figure 1 for locations) ------18 Table 2. Mean monthly discharge in thousands entering Pool 13 from Lock and Dam 12, upper Mississippi River, January 1978 through August 1980 ------41 Table 3. Current velocity (cm/s) at 0.6 of the depth (mean velocity) at benthos sites {refer to Figures 1 and 2 for locations) and staff gauge ~eadings {m) at Lock and Dam 12, Pool 13, upper Mississippi River for each sampling month ------42 Table 4. Bottom current velocity {cm/s) at benthos sites in the side channel and at each wing dam before and after notching, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------43 Table 5. Summary comparison of current velocities in the side channel and at each wing dam before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River {refer to Figures 1 and 2 for locations) ------45 Table 6. Mean percent silt-clay, mean percent sand, and mean percent gravel in the substrate in the side channel and at each wing dam, before and after notching, Pool 13, upper Mississippi River ------47 Table 7. Benthic invertebrate density {No.) and biomass {g) per m2, and number of taxa collected with a 252-cm2 Ponar grab, in the side channel and at each wing dam, before and after notching, Pool 13, upper Mississippi River ------55

Tab 1e 8. r~ean density {No. ) per m2 and percent of total benthic invertebrate density for major taxa before and after notching, Pool 13, upper Mississippi River ------67

viii Page Table 9. Macroinvertebrate aufwuchs ·combined. density (No.) and biomass (g) per m2 from basket and multiple-plate artificial substrates, Pool 13, upper Mississippi River (refer to Figure 1 for locations) ------69 Table 10. Summary comparison of electrofishing catch per unit effort for all species combined and for freshwater drum, sauger, and carp before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------73 Table 11. Sumnary comparison of electrofishing catch per unit effort for selected species before and after notching, without adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------75 Table 12. Summary comparison of catch per unit effort before and after notching for all species combined and for selected species in unbaited and baited hoop nets, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------77 Table 13. Mean catch per unit effort (No./haul) for major families of fishes in seine catches before and after notching in the side channel, Pool 13, upper Mississippi River (refer to Figures 1 and 6 for locations) ------80

ix LIST OF FIGURES Page Figure 1. Wing dams 25, 26, 28, 29, 30, 31, and an adjacent side channel in Pool 13 of the upper Mississippi River ------7 Figure 2. Hydrographic relief and benthos sites A) and location of notches, at notched wing dams, B) at unnotched wing dams, C) in the side channel, Pool 13, upper Mississippi River ------12 Figure 3. Electrofishing transects and hoop net stations for wing dams 25 and 26, Pool 13, upper Mississippi River ------21 Figure 4. Electrofishing transects and hoop net stations for wing dams 28 and 29, Pool 13, upper Mississippi River ------22 Figure 5. Electrofishing transects and hoop net stations for wing dams 30 and 31, Pool 13, upper Mississippi River ------23 Figure 6. Electrofishing transects, hoop net stations, and seine stations in the side channel (chute) at river mile 548, Pool 13, upper Mississippi River ------24 Figure 7. Comparison of bottom current velocities at wing dam 25 (Figures for surface and mean velocities and for other dams and the side channel not shown) before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River ------29 Figure 8. Comparison of total electrofishing catch per unit effort at emergent wing dam shoreline transects (26-1S and 28-1S) before and after notching, after adjustment for changing river stage (figures for other locations not shown), Pool 13, upper Mississippi River (refer to Figures 1, 3, and 4 for locations) ------36 Figure 9. Mean percent sand in the side channel and at the wing dams for each sampling month, Pool 13, upper Mississippi River ------49

X Page Figure 10. Mean temperature (A) and dissolved oxygen concentration (B) at benthos and hydrographic relief sites for each sampling month in 1978 and 1979, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------52 Figure 11. Mean benthic invertebrate density (No.) and biomass (g) per m2 collected with a 252-cm2 Ponar grab in the side channel and at each wing dam for each sampling month, Pool 13, upper Mississippi River ------58

xi LIST OF APPENDICES Page Appendix A-1. Depth profiles along three hydrographic relief transects across wing dam 25 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------88 Appendix A-2. Depth profiles along three hydrographic relief transects across wing dam 26 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------~--- 97 Appendix A-3. Depth profiles along three hydrographic relief transects across wing dam 28 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------105 Appendix A-4. Depth profiles along three hydrographic relief transects across wing dam 29 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------114 Appendix A-5. Depth profiles along three hydrographic relief transects across wing dam 30 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------123 Appendix A-6. Depth profiles along three hydrographic relief transects across wing dam 31 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------132 Appendix A-7. Depth profiles along three hydrographic relief transects across the side channel during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------141

Appendix B. Aquatic macro~nvertebrate taxa collected with a 252-cm Ponar grab and artificial substrates during 1978, 1979, and 1980 from Pool 13, upper Nississippi River ------150

xii Page Appendix C. Fish species caught by electrofishing, hoop netting, and seining during 1978, 1~79~ a~d ~989 from Pool 13, upper MlSSlSSlPPl R1ver ------156 Appendix D. Subsample counts for large catches of Potamyia flava (Hagen) collected with a 252-cm2 Ponar grab, October 2 and 3, 1979, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) 159 Appendix E. Subsample counts for large catches of invertebrates collected with artificial substrates, October 6, 1979, Pool 13, upper Mississippi River (refer to Figure 1 for locations) ------160 Appendix F. Benthic invertebrate density (No.) per m2 collected with a 252-cm2 Ponar grab from the side channel and wing dams in each sampling period before and after notching, Pool 13, upper Mississippi River ------~------162 Appendix G. Comparison of current velocities before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River ------165 Appendix H. Comparisons (t-tests) of percent silt-clayi percent sand, and percent gravel in the substrate in the side channel and at each wing dam before and after notching, Pool 13, upper Mississippi River ------169 Appendix I. Mann-Whitney tests of benthic invertebrate density (No.) and biomass (g) per m2 an~ number of taxa collected with a 252-cm Ponar grab in the side channel and at each wing dam, before a~d ~ft~r ~ot~hing, Pool 13, upper MlSSlSSlppl R1ver ------171 Appendix J. Kruskal-Wallis tests and nonparametric multiple comparisons (Zar 1974} of benthic invertebrate density (No.) per m2 collected with a 252-cm2 Ponar grab in each sampling month, Pool 13, upper Mississippi River ------173

xiii Page Appendix K. Kruskal-Wallis tests and nonparametric multiple comparisons (Zar 1974) of benthic invertebrate biomass (g) per m2 collected with a 252-cm' Ponar grab in each sampling month, Pool 13, upper Mississippi River ------180 Appendix L. Comparison of electrofishing total catch per unit effort before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------'------187

Appendix ~1. Comparison of electrofishing catch per unit effort for freshwater drum, sauger, and carp before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------190 Appendix N. Median and mean catch per unit effort (No./30 min) of selected species in electrofishing catches before and after notching, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) ------194 Appendix 0. Median and mean catch per unit effort (No./24 h) in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River ------200 Appendix P. Median and mean catch per unit effort (No./24 h) of selected species in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River ------202 Appendix Q. i4ann-Whitney tests of catch per unit effort (No./30 min) for selected species in electrofishing catches before and after notching, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations) 208 Appendix R. Mann-Whitney tests of total catch per unit effort (No./24 h) in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River ------213 xiv Page Appendix S. Mann-Whitney tests of catch per unit effort (No./24 h) for selected species in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River ------214 Appendix T. Lengths (mm) and weights (g) of selected species in electrofishing catches before and after notching, Pool 13, upper Mississippi River ------218 Appendix U. Lengths (mm) and weights (g) of selected species in hoop net catches before and after notching, Pool 13, upper Mississippi River ------219 Appendix V-1.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, June 12, 17, 18, 20, 21, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------220

Appendix V-2.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, August 2-4, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations} ------222 Appendix V-3.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, September 29-30, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations} ------224 Appendix V-4.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, June 5-6, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------~-- 226 Appendix V-5.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, August 2-3, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------228 Appendix V-6.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, October 2-3, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------230

XV Page Appendix V-7.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, June 3-4, 1980, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------232 Appendix V-8.* Temperature, dissolved oxygen, velocity, and depth at benthos sites, July 30-31, 1980, Pool 13, upper Mississippi River {refer to Figure 2 for locations) ------234 Appendix W-1.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, June 21-23, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------236 Appendix W-2.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, August 4, 5, 7, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------240 Appendix W-3.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, September 30, October 2-3, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------244 Appendix W-4.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, June 6-7, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------248 Appendix W-5.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, August 3-8, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------251 Appendix W-6.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, October 4, 7, 8, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------255

xvi Page Appendix W-7.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, June 4-6, 1980, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------259 Appendix W-8.* Temperature, dissolved oxygen, velocity, and depth at hydrographic relief sites, July 31, August 1, 1980, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------263 Appendix X.* Particle size fractions as percent total in 100 gtam samples (Ingram 1971) collected with a Ponar grab, benthos sites, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------267 Appendix Y.* Particle size fractions as percent total in 100 gram samples (Ingram 1971) collected with a Ponar grab, hydrographic relief sites, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------278 Appendix Z-1.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), June 12, 17, 18, 20, 21, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------292 Appendix Z-2.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), August 2-4, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------308 Appendix Z-3.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), September 29-30, 1978, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------318 · Appendix Z-4.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three repli~ates), June 5-6, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------336 xvii Page Appendix Z-5.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), August 2-3, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------347 Appendix Z-6.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), October 2-3, 1979, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------369 Appendix Z-7.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), June 3-4, 1980, Pool 13, upper Mississippi River (refer to Figure 2 for locations) ------397 Appendix Z-8.* Number and biomass per square meter of macroinvertebrates collected with a Ponar grab (three replicates), July 30-31, 1980, Pool 13, upper Mississippi. River (refer to Figure 2 for locations) ------416 Appendix AA.* Benthic invertebrate counts (No.) in samples collected with a 252-cm2 Ponar grab, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------~------441 Appendix BB.* Benthic invertebrate biomass (g) 2 in samples collected with a 252-cm Ponar grab, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------443 Appendix CC.* Number of benthic invertebrate taxa in samples collected with a 252-cm2 Ponar grab {replicates combined), Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations) ------445 Appendix DD.* Number and biomass per square meter of macroinvertebrates collected with a basket sampler, Pool 13, upper Mississippi River {refer to Figure 1 for locations) -----~------446 xviii. Page Appendix EE. * Number and biomass per square meter of macroinvertebrates collected with a multiple-plate sampler, Pool 13, upper Mississippi River (refer to Figure 1 for locations) ------460 Appendix FF.* Number and biomass per square meter of macroinvertebrates collected with a multiple-plate sampler & basket sampler. Pool 13, upper Mississippi River (refer to Figure 1 for locations) ~------469 Appendix GG-1. * Electrofishing catches for each transect during June 1978 (refer to Figures 1, and 3 to 6 for locations) ------~------470 Appendix GG-2.* Electrofishing catches for each transect during August 1978 (refer to Figures 1, and 3 to 6 for . locations) ------~----- 486 Appendix GG-3.* Electrofishing catches for each transect during October ·1978 (refer to Figures 1, and 3 to 6 for locations) ------~-----~------~----- 506 Appendix GG-4.* Electrofishing catches for each transect during June 1979 (refer to Figures 1, and 3 to 6 for locations) ------524 Appendix GG-5.* Electrofishing catches for each transect during August 1979 (refer to Figures 1, and 3 to 6 for locations) ------539 Appendix GG-6.* Electrofishing catches for each transect during October 1979 {refer · to Figures 1, and 3 to 6 for locations) ------556 Appendix GG-7.* Electrofishing catches for each transect during June 1980 (refer to Figures 1, and 3 to 6 for locations) ------576

Appendix GG-8.* El~ctrofishing catches for each transect during August 1980 (refer to Figures 1, and 3 to 6 for locations) ------592 xix Page Appendix HH-1.* Unbaited and baited hoop net catches for each site during June 1978 (refer to Figures 1, and 3 to 6 for locations) ------614 Appendix HH-2.* Unbaited and baited hoop net catches for each site during August 1978 (refer to Figures 1, and 3 to 6 for locations) ------639 Appendix HH-3.* Unbaited and baited hoop net· catches for each site during October 1978 (refer to Figures 1, and 3 to 6 for locations) ------~------667 Appendix HH-4.* Unbaited and baited hoop net catches for each site during June 1979 (refer to Figures 1, and 3 to 6 for locations) ---~-- 695 Appendix HH-5.* Unbaited and baited hoop net catches for each site during August 1979 (refer to Figures 1, and 3 to 6 for locations) ------~------723 Appendix HH-6.* Unbaited and baited hoop net catches for each site during October 1979 (refer to Figures 1, and 3 to 6 for locations) ------~------751 Appendix HH-7.* Unbaited and baited hoop net catches for each site during June 1980 (refer to Figures 1, and 3 to 6 for locations) ------779 Appendix HH-8.* Unbaited and baited hoop net catches for each site during August 1980 (refer to Figures 1, and 3 to 6 for locations) ------807 Appendix II.* Seine catches in the side channel, Pool 13, upper Mississippi River (refer to Figures 1 and 6 for locations) ------~------835 Appendix JJ-1.* Lengths (mm) and weights (g) for each species in electrofishing catches in June 1978, Pool 13, upper Mississippi River ------843 Appendix JJ-2.* Lengths (mm) and weights (g) for each species in electrofishing catches in August 1978, Pool 13, upper Mississippi River ------~------844

XX Page Appendix JJ-3.* Lengths (mm) and weights (g) for each species in electrofishing catches in October 1978, Pool 13, upper Mississippi River ------~- 845 Appendix JJ-4.* Lengths '._(mm) and weights {g) for each species in electrofishing catches in June 1979, Pool 13, upper Mississippi River ------846 Appendix JJ-5.* Lengths (mm) and weights (g) for e_ach species in electrofishing catches in August 1979, Pool 13, ~pper Mississippi River ------~------847 Appendix JJ-6.* Lengths (mm) and weights (g) for each species in electrofishing catches in October 1979, Pool 13, upper Mississippi River ------848 Appendix JJ-7.* Lengtbs {mm) and weights (g) for each species in electrofishing catches in June 1980, Pool 13, upper Mississippi River ------849 Appendix JJ-8.* Lengths {mm) and weights (g) for each species in electrofishing catches in August 1980, Pool 13, upper Mississippi River ------~------850 Appendix KK-1.* Lengths (mm) and weights (g) for each species in hoop net catches in June 1978, Pool 13, upper Missi~sippi River ------~------~-- 851 Appendix KK-2.* Lengths (mm) and weights (g) for each species in hoop net catches in August 1978, Pool 13, upper Mississippi River ------852 Appendix KK-3.* Lengths (mm) and weights (g) for each species in hoop net catches in October 1978, Pool 13, upper Mississippi River ------~------853 Appendix KK-4.* Lengths (mm) and weights {g) for each species in hoop net catches in June 1~79, Pool 13, upper Mississippi R1ver ------~-----~--- 854

xxi Page Appendix KK-5.* Lengths (mm) and weights (g) for each species in hoop net catches in August 1979, Pool 13, upper Mississippi River ------855 Appendix KK-6.* Lengths (mm) and weights {g) for each species in hoop net catches in October 1979, Pool 13, upper Mississippi River ------856 Appendix KK-7.* Lengths (mm) and weights (g) for each species in hoop net catches in June 1980, Pool 13, upper Mississippi River ------857 Appendix KK-8.* Lengths {mm) and weights (g) for each species in hoop net catches in August 1980, Pool 13, upper Mississippi River ------858 Appendix LL-1.* Staff gauge levels (m) at Lock and Dam 12 for data collected at hydrographic relief sites durtng 1978, 1979, and 1980, upper Mississippi River ------~------859 Appendix LL-2.* Staff gauge levels {m) at Lock and Dam 12 for data collected at benthos sites during 1978, 1979, and 1980, upper Mississippi River ------863 Appendix LL-3.* Staff gauge levels {m) at Lock ~nd Dam · 12 for electrofishing catches during 1978, 1979, and 1980, upper Mississippi River ------867 Appendix LL-4.* Staff gauge levels {m) at Lock and Dam 12 for hoop net catches during 1978, 1979, and 1980, upper Mississippi River ------~---- 872

* Appendix V through LL available on request from:

Federal Documents Section Learning Resources Genter UW-Stevens Point Stevens Point, WI 54481

xxii CONCLUSIONS

Negative effects of notching wing dams in the study area seemed to outweigh the one apparent positive effect, which was the occurrence of high densities of benthic invertebrates associated with exposure of gravel below the notch in dam 26 in the fall of 1979. Negative effects appeared to be an increase in sand deposition in the side channel, inhibition of benthos populations in the side channel due to the increase in sand, and a reduction in the amount of productive subtrate for aquatic organisms caused by removal of wing dam rock. Notching may have aggravated rather than alleviated accretion of sediments in the side channel. Simons et al. (1974) concluded from experiments with laboratory models that, to maintain a side channel, it must receive no more than its "fair share" of the sediment load carried by the river. If notching increases the amount of sediment entering a side channel without increasing bottom velocities enough to prevent its deposition, accretion of sediments will occur (Pierce 1980). My data suggest that notching may have caused a long-term increase in sediment deposition in the side channel. Simons et al. (1974) felt that notching wing dams would extend. the life of few side channels because notched dams generally cannot be located in the proper position to prevent increased sedimentation. Water sweeping over submerged wing dams may reduce sedimentation associated with such structures. Simons et al. (1974) found that the higher the dam, the more rapidly a small side channel filled with sediment, and the more rapidly a bar was produced below the

1 2 dam. Burke and Robinson (1979) found that lowering wing dikes on the Missouri River so that they were submerged 95% of the time prevented accretion elevations that could support permanent vegetation. The predominantly submerged character of the wing dams in the study area may be more important than notching in reducing accretion of sediments between the dams and in the side channel. INTRODUCTION

The U.S. Army corps of Engineers submitted plans on June 30, 1977 to the Great River Environmental Action Team II (GREAT II) for repair of wing dams in Pools 13 and 19 of the upper Mississippi River; The Fish and Wildlife Management Work Group of GREAT II proposed the construction of notches in some of the wing dams to help alleviate some of the detrimental effects of accreted sediments between wing dams. Wing dikes have been notched in the Missouri River to reduce accreted sediments between the dikes and in backwater areas (Kallemeyn and Novotny 1977, Reynolds 1977, Jennings 1979, Dieffenbach 1980) (Hall 1980). The objectives of this study were to determine effects of wing dam notching on fish, aquatic macroinvertebrates, and physicochemical characteristics at. six wing dams and an adjacent side channel in Pool 13 of the upper Mississippi River. This investigation took place in 1979 and 1980 and was the postnotching phase of the study. The prenotching phase was conducted in 1978 and the spring of 1979, when fishpopulations.in the study area and physicochemical characteristics at hydrographic relief sampling sites were investigated by Pierce (1980), and aquatic macroinvertebrates, sediments, and physicochemical characteristics at benthos sampling sites were investigated by Hall (1980); both investigators were students in the Wisconsin Cooperative Fishery Research Unit. Three wing dams were notched in May-June-July 1979. Samples during the prenotching phase of the study were collected during the months of June, August, and September-October 1978, and June 1979; during the postnotching phase, samples were collected during August and October 1979, and June and July-August 1980.

3 4

Wing dams are rock-rubble structures extending from the river bank to the main channel. Wing dams, commonly referred to as wing dikes on the Missouri River, have been constructed to deflect current toward the main channel to help maintain a navigation channel and reduce the need for recurrent dredging. Slack water areas have often developed behind wing dams resulting in accretion of sediments between them and in adjacent backwaters. Diverse habitats for fish, invertebrates, and wildlife have been lost as a result of this sediment deposition in off-channel areas (Funk and Robinson 1974, Simons et al. 1975, Breitenbach and Peterson 1980, Hall 1980, Pierce 1980). Thousands of wing dams were built in the upper Mississippi River by the U.S. Army Corps of Engineers to help maintain the 4.5 and 6-foot navigation channels authorized by Congress in 1890 and 1907. In the 193o•s, a series of 29 locks and dams was constructed to maintain the 9-foot navigation channel. Lock and dam constru.ction caused a permanent rise in water level and submerged many of the wing dams in the upper Mississippi River (Breitenbach and Peterson 1980, Pierce 1980). The effects of wing dam notching have been variable. Success ·has been related to wing dam height, location of notches in dams, discharge, and location of the dam in relation to the thalweg (Simons et al. 1974, Reynolds 1977, Jennings 1979, Hall 1980, Pierce 1980). Notching has increased habitat diversity for fish in channelized portions of the Missouri River (Kallemeyn and Novotny 1977, Jennings 1979, Pierce 1980). GREAT II was organized to study the upper Mississippi River from Guttenberg, Iowa, to Saverton, Missouri, as part of the Great River Study authorized by Congress in the Water Resources Development Act 5 of 1976 (PL 94-587). The GREAT II team was composed of representatives of the upper Mississi~pi River basin states and federal river resource-oriented agencies. The goal of GREAT was to develop a river resource management plan that was "technically and economically sound, socially and environmentally acceptable, and capable of being put into action within a reasonable period of time" (Breitenbach and Peterson 1980). STUDY AREA

The study area encompassed wing dams 25, 26, 28, 29, 30, and 31 between river kilometers 880.7 and 882.7 (river miles 547.4 and 548.6) and an unnamed side channel between river kilometers 880.9 and 881.9 (river miles 547.5 and 548.1) in the upper end of Pool 13 of the upper Mississippi River (Fig. 1). Pool 13 was created by construction of Lock and Dam 13 north of Fulton, Illinois, in 1939 and extends 55 kilometers north to Bellevue, Iowa. At ·flat pool, Pool 13 is maintained at 178 m above sea level and has 11,778 hectares of water surface of which 2,945 (25%) are classified as channel. Of the 814 kilometers of pool shoreline, 94% is federally owned (U.S. Army Corps of Engineers 1974, Hall 1980, Pierce 1980). The bedrock in the area of the pool consists of Galena dolomite and Maquoketa shale from the Ordovician age.. Depth to bedrock ranges from 9 to 46 m. There are no glacial deposits in the northern area of Pool 13; glacial deposits in the southern area of the pool are of the Illinoian and Kansan stages. The floodplain soils are silt-clay deposited 1 to 6 m deep overlying sand. Pool 13 drains an area of 221,445 square kilometers. Approximately 1,415,232 metric tons of sediment enter Pool 13 annually (U.S. Army Corps of Engineers 1974). The riverbed consists of sand with lesser amounts of silt-clay, gravel, and boulders. The wing dams in the study area extended into the river as much as 400 m from the Illinois bank and, for the purposes of this investigation, were classified as either submerged or emergent. Wing dams 25, 29, 30, and 31 remained under water during periods of low flow and were termed submerged wing dams. Wing dams 26 and 28 were

6 7

SAVANNA. PROVING GROUNDS

Iowa LEGEND c::=: Emergent wing dam Submerged wing dam c:------.:::-.::::.==:::30 t== J Main channel - Dredge spoi 1 disposal sites (1945-1975)

0 !00 ::?OOm

FIGURE 1. Wing dams 25, 26, 28, 29, 30, 31, and an adjacent side channel in Pool 13 of the upper Mississippi River. 8 high enough to breach the water surface at river stages less than 2.13 and 2.75 m respectively, and were termed emergent wing dams. Emergent wing dams were typically submerged during spring sampling periods. Wing dam 27 was similar in form and height to wing dam 26 but was not investigated. Two classes of habitat, main channel border and side channel, as defined by the Upper Mississippi River Conservation Commission {Sternberg 1971), were present in the study area. Main channel border was that area between the navigation channel and the river bank in which the wing dams were located. Side channels, as defined by the UMRCC, are departures from the main channel and main channel border in which there is current during normal river stages. The side channel in the study area, also referred to as a chute, had some current present at all times. The substrate in both the main channel border and side channel consisted primarily of sand with varying amounts of silt and clay, and little or no rooted vegetation. Some patches of gravel were found in the main channel border. The Illinois bank was primarily open with scattered trees, whereas the islands, shorelines of the side channel, and the Iowa bank were more densely covered river bottom woodlands. Fallen trees and emergent willows wer~ most plentiful in the side channel. Some rock rip-rap occurred along the main channel border shorelines adjacent to wing dams 25, 26, and 28, and to wing dam 29 after it was repaired in the spring of 1979. The side channel offered access to other backwater areas during high river stages. The reach between river kilometers 878.5 and 883.0 (river miles 546.0 and 548.8) is classified by the U.S. Army Corps of Engineers 9

(1974) as a recurrent dredging area. Since 1945, 1,373,293 cubic meters of dredge spoil have been removed from the area (U.S. Army Corps of Engineers 1974). In the past, dredge spoil has been disposed of between the wing dams in the study area and on the Iowa bank (Fig. 1). The Maquoketa River, which enters Pool 13 opposite the study area, introduces about 417,312 metric tons of sediment to Pool 13 annually (Hall 1980). In May, June, and possibly July of 1979, a notch was placed in wing dams 25, 26, and 28 (Fig. 2), and wing dam 29 was repaired. Centers of the notches in wing dams 25, 26, and 28 were about 85, 105, and 45 m, respectively, from the Illinois bank. In notching, a complete section of wing dam was removed so that notches extended all the way to the river bottom. Notch widths were about 45 m for dam 25, and 75 m for dams 26 and 28. The notched portion of wing dam 25 was not extant even before the spring of 1979 so that dam 25 was actually

11 notched 11 throughout the study period, as explained in Results and Discussion. Because notching was occurring during June 1979 sampling, data (which are included in the Appendix) obtained then were not included in comparisons of prenotching and postnotching current velocities, substrate composition, and aquatic invertebrate and fish populations. METHODS

Sampling and Sample Processing

Discharge and Staff Gauge

Mean monthly discharge data were provided by Chief G. E. Johnson, Rock Island District, U.S. Army Corps of Engineers. Hourly staff gauge measurements for the tailwaters of Lock and Dam 12 were obtained from Corps of Engineers personnel at the lock and dam.

Hydrographic Relief

Hydrographic relief information was obtained on June 21-23, August 4, 5, 7, September 30, October 2, 3, 1978, and June 6, 7, 1979 in the prenotching phase; and August 3-8, October 4, 7, 8, 1979, and June 4-6, July 31, August 1, 1980 in the postnotching phase of the study. Three hydrographic relief transects were established across each wing dam and the side channel. Wing dam transects were about 61 m {200 ft) long and were located perpendicular to the wing dams at about the following distances from the Illinois bank:

Wing dam 25 - 90, 150, and 215 m Wing dam 26 - 105, 170, and 260 m Wing dam 28 - 60, 120, and 245 m Wing dams 29, 30, and 31 - 60, 135, and 215 m.

Side channel transects were located across the upper, central, and

10 11 lower sections of the channel and were about 800, 400, and 70 m from its lower opening. Distances of wing dam transects from the Illinois bank and lengths of side channel transects were measured with a Rangemetic range finder. Depths from a Vexilar sonar depth finder were recorded at 5-second intervals while a boat moved at a constant speed upstream along wing dam transects or perpendicular to the current along side channel transects (Lind 1979). No hydrographic relief information was obtained at wing dam 26 in June 1979 because the Army Corps of Engineers was notching the dam at that time (Pierce 1980). To aid in comparing bottom configurations between months, all depths were adjusted for a standard river stage (staff gauge level = 2.32 m) and plotted as cross-sections (App. A).

Hydrographic Relief and Benthos Sampling Sites

Ten sites at each wing dam and fifteen sites in the side channel were established for collecting physicochemical information (Fig. 2). Six sites at each wing dam and twelve in the side channel were located on the hydrographic relief transects described in the previous subsection and were termed hydrographic relief sites. At the wing dams, hydrographic relief sites were located at the upstream and downstream ends of each hydrographic relief transect. In the side channel, four hydrographic relief sites were established along each hydrographic relief transect. The remaining sampling sites (four at each wing dam and three in the side channel) were termed benthos sites because benthic '· •25-3-4 •25-2-4 •25-1-4

•25-1-7 Wtng Da11 25 ------•25-2-8 25-4-8 -25-3-5 •25-2-5 • •25-1-5 •25-3-8

•26-1-4 •26-1-7 Wtng 0411 26 ~------~~------~------~ ~------~------~~------~•26-2-8 26-4-8 •26-3-5 •26-2·5 • •26-1-5 •26-3-8 ...... N

.zs-3-4 •28-2-4 • 28-1-4 Wing 0411 28 •28-1-7

r------~------~------...... ------.. ---•28-2-8.. 28-4-8 •28-3-5 •28-2-5 •• 28-1-5 •28-3-8 0 50 lOOm •

Figure 2. A) Hydrographic relief and benthos sites, and location of notches, at notched wing dams, Pool 13, upper Mississippi River. Hydrographic relief sites: 1-4, 1-5, 2-4, 2-5, 3-4, 3-5. Benthos sites: 1-7, 2-8, 3-8, 4-8. ·29·3·4 '· •29·2-4 •29·1-4

•29-6-7 •29-5-7 Wing Dam 29 ·29-6-8 ·29-5-8

.Z9-3-5 .Z9-2-5 •29-1-5

•30-3-4 •30-2-4 • 30-1-4

•30-6-7 • 30-5-7 Wtng Dam 30

~30-6-8 • 30-5-8

•30-3-5 -30-2-5 • 30-1-5

...... w

r 0 50 lOOm

Figure 2. (continued.) B) Hydrographic relief and benthos sites at unnotched wing dams, Pool 13, upper Mississippi River. Hydrographic relief sites: 1-4, 1-5, 2-4,. 2-5, 3-4, 3-5.

Benthos sites: 1-7~ 2-8, 3-8, 4-8. 14

lOOm

Figure 2. (continued.) C) Hydrographic relief and benthos sites in the side channel, Pool 13, upper Mississippi River. Hydrographic relief sites: 9-6, 9-7, 9-8, 9-9, 10-6, 10-7, 10-8, 10-9, 11-6, 11-7, 11-8, 11-9. Benthos sites: 9, 10, 11. 15

invertebrate samples, as well as physicochemical information, were collected at those sites. Benthos sites at wing dams 25, 26, and 28 were located in the vicinity of the notched portions of the dams. At each of those dams, one site was located 8 m upstream of the dam's base in line.with the center of the portion of the notch. The remaining three benthos sites at each notched dam radiated downstream from the notch center at angles 45°, 90°, and 135°, when the proximal end of the dam (Illinois bank) was considered to be 0° and the distal end (channel) 180°, and were 8, 38, and 23m, respectively, from the base of the dam. Benthos sites at unnotched dams 29, 30, and 31 were located 8 m upstream and downstream from the base of the dam on transects 61 and 152m from the Illinois bank. ·Side channel benthos sites in upper, central, and lower sections of the side channel were: 15m from the west bank at river kilometer 881.7 (river mile 548.0), 15m from the east bank at river kilometer 881.4 (river mile 547.8), and 15m from the west bank at river kilometer 881.1 ·(river mile 547.6). for notched dams, only those data below notched sections--hydrographic relief site 1-5 and benthos sites 2-8, 3-8, and 4-8-- were included in current velocity, substrate, and benthos analyses because it was believed that effects of notching on those characteristics would have been most pronounced at those sites. 16

Physicochemical Characteristics

Physicochemical information was obtained at each hydrographic relief site at the time of bottom mapping and at each benthos site at the time of benthic invertebrate sampling. Water temperature, dissolved oxygen concentration, and current velocity were measured, and sediments collected at all sites, except at hydrographic relief sites in the side channel where sediment samples were not taken (Fig. 2). Water temperature and dissolved oxygen concentration were determined at each meter of the water column and at the surface and bottom with an air-calibrated YSI Model 54 Oxygen Meter. Current velocity was recorded at the water surface; at 0.2, 0.6, and 0.8 of the depth; and 10 em fr.om the bottom with a cable-suspended Price · current meter (Hynes 1970). One sediment sample per site was collected with a 252-cm2 Ponar grab. Sediments were analyzed for particle size by the procedure of Ingram (1971} and divided into 10 particle size fractions based on the modified Wentworth scale (Wentworth 1922, Cummins 1962). No attempt was made to separate fine sediments into silt and clay fractions (Hall 1980). 17

Aquatic Macroinvertebrates

Benthic invertebrates were collected with a 252-cm2 Ponar grab sampler on June 12, 17, 18, 20, 21, August 2-4, September 29, 30, 1978, and June 5, 6, 1979 in the prenotching phase of the study; and on August 2, 3, October 2, 3, 1979, and June 3, 4, July 30, 31, 1980 in the postnotching phase. Three replicate samples were taken at each benthos site (Fig. 2). Also, two kinds of artificial substrate invertebrate samplers were set once before and once after notching on each wing dam and left for six to eight weeks to allow for colonization by macro­ invertebrates (Mason et al. 1973, Hall 1980). Two basket samplers and two multiple-plate substrates were set on each of two transects per dam (Table 1, Fig. 1), except at wing dams 25, 26, and 28 after notching artificial substrates were set only on outside transects. On each transect, one basket and one multiple-plate sampler were set on the upstream and on the downstream side of the wing dam. Basket samplers consisted of 28 x 18 em cylindrical metal baskets containing 10 concrete spheres 7.5 em in diameter (Mason et al. 1967, Jacobi 1971). Multiple-plate substrates were made from 2-mm tempered hardboard (masonite), with eight alternate layers of 7.5-cm squares and seven 2.5 em squares attached to an 8-cm ring bolt (Hester and Dendy 1962, Hall 1980). The artificial substrates were tied to a 1-cm diameter rope, which was draped over the wing dam and was anchored upstream from the dam by a steel reinforcing rod driven into the bottom. Artificial substrates were retrieved on September 28 and October 18

Table 1. Locations of artificial substrate transects (meters from Illinois bank), Pool 13, upper Mississippi River (refer to Figure 1 for locations).

Transect

Wing dam Inside Outside

25a 64 152 26a 79 183 28a 105 213 29 61 213 30 61 213 31 61 213 aArtificial substrates were not set on inside transects on wing dams 25, 26, and 28 after notching. 19

2, 3, 1978 in the prenotching phase, and October 6, 1979 in the postnotching phase of the study. Twenty eight (58% of those set) of the artificial substrates were recovered before notching and 27 (75%) were recovered after notching. Basket and multiple-plate samplers from three locations on notched dams and from four locations on unnotched dams were recovered both before and after notching. A washtub was placed below each sampler before it was removed from the water to help prevent loss of organisms (Bull 1968, Hilsenhoff 1969, Mason et al. 1973). The substrates were dismantled in the washtubs and scrubbed to remove invertebrates. Only those organisms on the spheres ~r plates were used in the quantitative analysis. Organisms attached to the wire basket, debris, or vegetation were discarded (Hall .1980). All samples were sieved through a U.S. No. 30 (0.595 mm) screened wash bucket, placed in plastic bags containing 5% formalin (Lind 1979), and taken to the laboratory for processing. In the laboratory, invertebrates were sorted from debris, subsampled (Cummins 1975: section 8.23, Elliott 1977: section 8.3) (App. D and E), identified and counted. Samples were sorted in white-bottomed trays with the aid of low-power magnifying lenses and binocular dissecting scopes. Elutriation (Stewart 1975) was used as an aid in sorting of samples collected at wing dams 30 and 31 in June 1980 and samples collected in July 1980. Identification was facilitated by use of taxonomic keys of Eddy and Hodson (1961), Parmalee (1967), Borror and Delong (1971), Burch (1972, 1973), Hilsenhoff (1975), McCafferty (1975), Edmunds et al. (1976), Wiggins (1978), Merritt and Cummins (1978), Pennak 20

(1978}, Schuster et al. (1978), and Fuller (1980). Oligochaetes were too fragmented in screening to be identified further than class; numbers were estimated by counting prostomia. Invertebrate biomass was calculated from organism length {Hynes and Coleman 1968) for all but Oligochaeta, Zygoptera, and Unionidae. Hynes and Coleman (1968) assumed invertebrates to be cylinders in which volume increased by the cube of the length and with a specific gravity of 1.05 (Hall 1980). Weights for invertebrates with lengths equal to five diameters were 3.298 x 10-5 g times the length cubed; Chironomidae and Ceratopogonidae with lengths equal to 7.5 diameters were 1~393 x 10-5 g times the length cubed; and Gastropoda and Sphaeriidae, which were considered spheres, were 4.398 x w- 3 g times the radius cubed. Unionidae with and without shell, and Zygoptera were soaked in water 30 minutes, blotted dry, and weighed on a Mettler H54 balance to the nearest mg. Oligochaeta were soaked for 30 minutes in water, centrifuged at 650 rpm for three minutes (Howmiller 1972, Stanford 1973), and weighed to the nearest mg (Hall 1980).

Fish

Fish were caught with the aid of alternating current electrofishing gear, hoop nets, and small-mesh seines during each of the four prenotching and four postnotching sampling periods. Electrofishing gear consisted of a boom shocker (Novotny and Priegel 1974) operated at 7-12 amperes. Three transects on wing dam 25 and four transects on the remaining five wing dams were established for electrofishing (Figs. 3 to 5). Wing dam 21

LEGEND Wing dam

~ Electrofishing transect

Hoop net station

Meters

0 300

Figure 3. Electrofishing transects and hoop net stations for wing dams 25 and 26, Pool 13, upper Mississippi River. Electrofishing site codes: 1S = shoreline transect; A, B, C = outside transects. Hoop net site codes: U = upstream, D = downstream, I = inside, 0 = outside. 22

LEGEND == Wing dam 0 Electrofishing transect

~ Hoop net station

Meters

0 . 300

Figure 4. Electrofishing transects and hoop net stations for wing dams 28 and 29, Pool 13, upper Mississippi River. Refer to Figure 3 for description of site codes. 23

LEGEND Wing dam

Electrofishing transect

, Hoop net station

Meters 0 300

Figure 5. Electrofishing transects and hoop net stations for wing dams 30 and 31, Pool 13, upper Mississippi River. Refer to Figure 3 for description of site codes. 24

I I• I ICE I Legend .__..j,----, Electrofishing transect ... Hoop net station - Seine station

Meters

0 300

Figure 6. Electrofishing transects, hoop net stations, andseine stations in the side channel (chute) at river mile 548, Pool 13, upper Mississippi River. Electrofishing site codes: CE = east bank transect, CW = west bank transect. Hoop net site codes: Cl, C2, C3, C4. Seine site codes: SHl, SH2, SH3, SH4, SHS. 25 electrofishing transects, which were perpendicular to and crossed each wing dam, consisted of one shoreline transect per dam and outside transects located between the following distances from the Illinois bank:

Wing dam 25 - (1) between 60 and 105 m (2) between 150 and 200 m Wing dam 26 - (1) between 75 and 120 m (2) between 170 and 215 m (3) between 260 and 305 m Wing dam 28 ·- (1) between 30 and 75 m (2) between 120 and 170 m (3) between 245 and 290 m Wing dams 29 and 30 - (1) between 60 and 105 m (2) between 135 and 190 m (3) between 230 and 275 m Wing dam 31 - (1) between 60 and 105m (2) between 120 and 170m (3) between 230 and 275 m.

Distances from the Illinois bank, measured with a Rangematic range finder, were marked with buoys. Shoreline transects extended about 50 m, and outside transects about 40 m upstream and downstream of each wing dam. Electrofishing effort at outside transects was concentrated over submerged wing dams and along the rock-rubble sides of emergent dams. One shoreline transect was established along each bank of the side channel (Fig. 6). Each electrofishing transect was fished twice at night with at least 72 hours between efforts. Shocking effort was usually 30 minutes per transect. Effort was reduced to 15 minutes at outside transects over submerged wing dams if no fish were being captured. A catch boat (Hubley 1963) was used to pick up fish missed by the 26 netting crew in the shocker boat (Pierce 1980). Four hoop nets (Greenbank 1946, Starrett and Barnickel 1955) were set at each wing dam and in the side channel (Figs. 3 to 6). Two nets were set above, and two below each wing dam at about 1/4 and 1/2 of the distance to the distal ends of the dams. Nets downstream from the wing dams were staked to the river bed within 20m of the dam and were allowed to trail downstream with the net opening downstream. Upstream nets were staked so that nets were less than 20 m upstream from wing dams. One hoop net was set in the upper section, two in the central section, and another in the lower section of the side channel, at distances of about 800, 400, and 70 m from the lower opening·of the side channel. Hoop nets had 2.5-cm (l-in.) bar mesh and mouths 0.76 m (2.5 ft) in diameter. Each net contained seven hoops and had two throats, one attached to each of the second and fourth hoops. Most nets were fished unbaited for two consecutive days, then baited with about 2 kg of soybean cake and fished for an additional two days. Due to difficulties in retrieving the nets, they were occasionally fished longer than two days (Pierce 1980). Three seine stations were established in the side channel (Fig. 6) where a total of three to five seine hauls were taken depending on river stage. Fewer hauls were made when river stage was high. A 0.6-cm (0.25-in.) mesh, 10-m long bag seine was used except in June 1978 when a 6-m long, 0.6-cm mesh straight seine was used. Seine hauls were 6 to 24 m long. Most captured fish were processed in the field. Total length 27

(Hile 1945) to the nearest mm, and weight to the nearest 2 or 10 g dependingon the scale used, were determined for most fish. Most minnows and certain other small fish were preserved for identification in the laboratory. Weights of preserved fish and lengths of 622 emerald shiners shocked in the side channel in August 1978 were not determined (Pierce 1980). Lengths and weights of fish with deformed or damaged bodies were not used in computing length and weight statistics.

Statistical Analyses

Current Velocity

Prenotching and postnotching bottom, surface, and mean velocities were compared after adjustment for changing river stage to determine effects of wing dam notching and repair on current velocities in the side channel and at each wing dam. For most comparfsons, the relation­ ship (regression) of current velocity to staff gauge level after notching (e.g. Fig. 7,A) was used to predict current velocities at prenotching staff gauge levels. Predicted and observed prenotching velocity values were then compared with a paired t-test (e.g. Fig. 7,8). Postnotching data were preferred for the predictive regression because ranges of velocity and staff gauge level values were wider after notching {Apps. V, W, and LL). However, when the regression of postnotching current velocity on staff gauge level was not significant, the predictive regression was calculated from prenotching data, and the paired t-test used to compare predicted and observed 28 postnotching velocities. Data from June, August, and September-October 1978 in the prenotching period, and August, October 1979, and June, July-August 1980 in the postnotching period were included in the analyses. When the predictive regression of current velocity on staff gauge level was calculated from postnotching data, June 1978 data were not included in the paired t-test because river stages during that sampling month were much higher than those after notching. When the predictive regression was calculated from prenotching data, July-August 1980 data were not included because river stages during that sampling period were much lower than those before notching. Data from hydrographic relief site 11-9 and benthos site 11 in the side channel were not included in current velocity analyses because those sites were in an area of slack water at low river stages (Fig. 2). Mean velocity values used in the analyses were determined by either of two methods (USDI Bureau of Reclamation 1971). The more accurate two-point method consisted of averaging velocity measurements from 0.2 and 0.8 of the depth from the water surface. The two-point method was always used except when one or both of the required velocity readings had not been obtained. Then, mean velocity was determined as the current velocity at 0.6 of the depth. 29

Figure 7. Comparison of bottom current velocities at wing dam 25 (Figures for surface and mean velocities and for other dams and the side channel not shm'ln) before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River. A) Data points {stars) and least squares regression line (r = 0.896, d.f .. = 14, £ <0.01) representing the relationship of bottom velocity to staff gauge level after notching. B) Postnotching predictive regression line from {A) on arithmet1c scale, and observed prenotching data points {diamonds). The portion of the regression line between the vertical bars represents the range of postnotching values. There was no significant difference between observed prenotching velocities and velocities predicted from the regression line (paired t-test, td = 2.06,

d. f. = 7' 0. 05 < Q < 0. 10) . Sample locations were benthos sites 2-8, 3-8 and 4-8, and hydrographic relief site 1-5 {refer to Figures

1 and 2 for locations). Prenotching months were August and September-October 1978. Postnotching months were August, October 1979, and June, July-August 1980. June 1978 data were not included in the analysis because of extremely high river stage during that month. 30

-1.00 ....*

-1.50

~ ·r-1 ~ * * ~ -2.00 .... * s~ * 5 -2.50

0.25 0.50 0.75 1.00 1.25 A) Ln Staff Gauge Level

0.30 r-i-

·~Ul .§. ~ 0.20 ·r-1 ~ ~

n.jJ 0.10 s

1.00 1.50 2.00 2.50 3.00 B) Staff Gauge Level (m} 31

Substrate·

Prenotching and postnotching percentages of silt-clay, sand, and gravel were compared to determine effects of wing dam notching and repair on substrate composition. The arcsines of the square roots of the percentages were averaged for each month and compared with two-sample t-tests (Zar 1974). Data from June, August, and September-October 1978 in the prenotching period, and August, October 1979, and June, July-August 1980 in the postnotching period were included in the analyses. Data from hydrographic relief site 1-4 at dams 29 and 30, and hydrographic relief site 1-5 at dam 31 were not used because samples were missing from those sites (Fig. 2).

Benthos

Because macroinvertebrates are usually distributed contagiously, large samples are often necessary to provide statistically accurate estimates of abundance (Mottley et al. 1938; Needham and Usinger 1956, cited by Resh 1979; Allen 1959; Taylor 1965; Egglishaw 1969; Sugimoto 1969; Cummins 1975; de March 1976; Elliott 1977; Minshall and Minshall 1977; Taylor et al. 1978; Resh 1979; Downing 1979; Hall 1980). Several authors have considered a percentage error of precision, calculated as D = (SE)(100)/X, of 20% to be a tolerable error for benthic samples (Cummins 1975, Elliott 1977, Resh 1979, Downing 1979, Hall 1980). I calculated 95% confidence intervals, chi-square variance 32 to mean ratios, k from the negative binomial distribution, 0, and the number of sampling units required for 0 = 20% for pooled benthos density data from all wing dams and the side channel for each sampling month with the formulae of Elliott (1977) (App. F). Although benthic invertebrates were contagiously distributed (significant chi-square, Q < 0.01) in each month, the percentage error for most sampling months was less than 20% for the pooled data. Nonparametric statistical methods were used to test differences between macroinvertebrate samples because the data did not satisfy assumptions of parametric statistical methods, i.e. normal distribution, variance independent of the mean, components of variance additive (Conover 1971, Zar 1974, Elliott 1977, Hall 1980). Prenotching and postnotching benthic density, biomass, and number of taxa were compared with Mann-Whitney tests. Data from June, August, and September 1978 in the prenotching period, and August, October 1979, and June 1980 in the postnotching period were used in the analysis of prenotching and postnotching taxonomic composition. July 1980 data were not included so that seasonal differences related to invertebrate life cycles were balanced between prenotching and postnotching periods (there was only one summer sample in the prenotching period), and because benthic invertebrate samples collected during that month were sorted with the aid of an elutriator (Stewart 1975), which seemed to increase sorting efficiency. Benthos density and biomass data were subjected to Kruskal-Wallis nonparametric analysis of variance and nonparametric multiple comparisons to test differences between individual sampling months (Zar 1974). Data for the elutriated July 1980 samples were included in this analysis. 33

Fish

A total of 106 comparisons were made of prenotching and postnotching electrofishing, hoop net, and seine catches. Prenotching and postnotching electrofishing and hoop net catches were compared for 1) side channel, 2) wing dam 25, 3) emergent wing dams (dams 26 and 28), and 4) unnotched wing dams (dams 29, 30, and 31). Within the above wing dam combinations, prenotching and postnotching electrofishing catches were compared for various transect groupings

( Fi g s . 3 to 5 ) :

Wing dam 25 - (1) 25-15 (2) 25-A & 25-B combined 8nergent wing dams - (1) 26-15 & 28-15 combined (2) 26-A & 28-A combined (3) 26-B & 28-B combined (4) 26-C & 28-C combined Unnotched wing dams - (1) 29-15, 30-15, & 31-15 combined (2) 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined.

Data from June, August, and October 1978 in the prenotching period, and August, October 1979, and June, August 1980 in the postnotching period were included in the analysis of fish catches. August 1979 and August 1980 data were pooled so that differences in abundance related to time of year were balanced between the prenotching and postnotching periods. (There was only one August sample in the prenotching period.) Geometric means of the August data pairs were used to pool electrofishing data. The geometric mean reduced the influence of very large electrofishing catches during the period of low river stage in August 1980 (Lewis 1963, Bagenal 1981). To facilitate calculation of the geometric mean, 34 when there was only one zero in a data pair, that zero was replaced with a one. Because hoop net and seine catches were not inordinate-ly large in August 1980, arithmetic means were used to pool the August data pairs for those gear. A total of 13,170 fish, including 56 species, were caught during the two phases of the investigation (Apps. C, GG to KK). The six species selected for individual analysis of electrofishing catches were freshwater drum (Aplodinotus grunniens), sauger (Stizostedion canadense), carp (Cyprinus carpio), bluegill (Lepomis macrochirus) shorthead redhorse (Moxostoma macroleoidotum), and quillback (Carpiodes cyprinus) (App. T). Five species selected for separate analysis of unbaited and baited hoop net catches were carp, smallmouth buffalo (Ictiobus bubalus), freshwater drum, channel catfish (Ictalurus punctatus), and flathead catfish (Pylodictis olivaria) (App. U). Those species were selected because of their prevalence in catches by the respective gear. Seine catches were analyzed for all species combined only. Because fluctuating discharge (river stage) influenced catches of fish, particularly electrofishing catches, before (Pierce 1980) and after notching, it tended to mask effects of notching on fish populations. In general, an increase in river stage corresponded to a decrease in fish catches. That relationship (correlation) was significant for electrofishing catches of all species combined and for some selected species {Apps. Land M), but was generally not significant for hoop net and seine catches. Significant correlation permitted comparison of prenotching and postnotching 35 electrofishing catches of all species combined and for some selected species after adjustment for changing river stage. Lack of significant correlation precluded analysis involving adjustment for changing river stage for other selected species in electrofishing catches, and for hoop net and seine catches. For most comparisons of prenotching and postnotching electrofishing catches involving adjustment for changing river stage, the relationship (regression) of catch per unit effort to staff gauge level after notching (e.g. Fig. 8,A) was used to predict catch per unit effort at prenotching staff gauge levels. Predicted and observed prenotching catch per unit effort were then compared with a Wilcoxon paired-sample· test (Conover 1971) (e.g. Fig. 8,B). The nonparametric Wilcoxon test was used, rather than the parametric paired t-test, because differences between paired values were not normally distributed (Zar 1974). Postnotching data were preferred for the predictive regression because ranges of catch per unit effort and staff gauge level values were wider after notching {Apps. GG and LL). For total electrofishing catch in the side channel, however, the regression of postnotching catch per unit effort on staff gauge level was not significant; therefore, the predictive regression was calculated from prenotching data, and the Wilcoxon test used to compare predicted and observed postnotching catch per unit effort. No attempt was made to compare prenotching and postnotching electrofishing catches of selected species, with adjustment for changing river stage, when the preferred postnotching regression was not significant, or when the number of 36

Figure 8. Comparison of total electrofishing catch per unit effort at emergent wing dam shoreline transects (26-1S and 28-1S) before and after notching, after adjustment for changing river stage (Figures for other transects and for other dams and the side channel not shown), Pool 13, upper Mississippi River (refer to Figures 1, 3, and 4 for locations). A) Data points (stars) and least squares regression line (r = -0.810, d.f. = 10, Q <0.01) representing the relationship of catch per unit effort to staff gauge level after notching. B) Postnotching predictive regression line from (A) on arithmetic scale, and observed prenotching data points (diamonds). The portion of the regression line between the vertical bars represents the range of postnotching values. There was no significant dJfference between observed prenotching catch per unit effort and catch per unit effort predicted from the regression line (Wilcoxon paired-sample test, T = 41.0, n = 11, 0.40

8.00 ~------~

+J 6.00 1-1 J3 4-l J::LI * ·a+J ::> 4.00 1-1 & ~ a 2.00 5 *

0.00 0.00 0.25 0.50 0.75 1.00 1.25 1.50

A) Ln Staff Gauge Level

150 . ·g 0 M ...... -8 100 t: J3 4-l J::LI +J ·a::> 50 1-1 ()) AI ~a 0 1.00 1.50 2.00 2.50 3.00 3.50 4.00 B) Staff Gauge Level (m) 38 pairs of matched unequal values in the Wilcoxon test was less than 6 (the minimum sample size, after omission of zero differences, required for Wilcoxon testing). For those electrofishing catches, prenotching and postnotching catch per unit effort were compared with Mann-Whitney tests, without adjustment for changing river stage. Not included in the analyses of total electrofishing catches were 722 emerald shiners caught at transect CW in August 1978, 300 emerald shiners at 31-1S in August 1978, and 154 river shiners at 31-1S in August 1980 (Figs. 5 and 6). Mann-Whitney tests also were used to compare prenotching and postnotching catch per unit effort for hoop net catches. Unbaited and baited hoop net catches were analyzed separately. Data were lacking for unbaited hoop nets at sites 28-DO, 30-UI, 30-DI, and 31-UO in June 1978, which were lost, and unbaited nets at C4, 29-DO, 30-DO, and the baited hoop net at 26-DO in June 1980, whfch opened while they were being fished (Figs. 3 to 6). Prenotching and postnotching seine catches of all species combined were compared by determining the number of fish taken within each of seven major families before and after notching, and then testing for significant differences with a Wilcoxon paired-sample test (Conover 1971). RESULTS AND DISCUSSION

Hydrographic Relief

No major changes in the configuration of river bottom adjacent to the wing dams or in the side channel were detected after notching, but changes in the structure of wing dams caused by notching and repair were evident (Apps. A-1 to A-7). Dam 26 was being notched during the June 1979 sampling period (App. A-2); dam 28 was notched after June but before the August 1979 sampling period (App. A-3). The portion of wing dam 25 where a notch was to be cut was not extant in 1978 nor throughout the study period. However, new rock appears to have been added to build up dam 25 on either side of the notch before June 1979 because an inside section of the dam was recorded during all but two sampling periods in 1979 and 1980 (App. A-1). Variability in location of the inside hydrographic relief transect (sampling error in use of the range finder) along the repaired dam might have caused the notch to appear in some postnotching months and not in others. The inside section of wing dam 29 also was not extant during the prenotching phase of the study but was constructed after the June 1979 sampling period, probably in late June or early July (App. A-4). All sections of wing dams 30 and 31 were extant throughout the study (Apps. A-5 and A-6). Variation in length of transects in the side channel (App. A-7) was caused by variability in range finder use and fluctuating water levels.

39 40

Discharge

Mean monthly discharge fluctuated between 700 and 3,900 m3/s during the period, January 1978 through August 1980 and generally was lower after notching than before (Table 2). Maximum monthly discharge in 1978 occurred in July (2,700 m3/s). This peak discharge in the summer of 1978 was atypical; the maximum normally occurs in spring (Hynes 1970, Hall 1980, Pierce 1980), as it did in 1979 and 1980. Mean monthly discharge for the summer months of July and August in 1979 and 1980 did not exceed 1,800 m3;s. Discharge is one of the most important factors influencing biological and physicochemical characteristics of a stream (e.g. leopold et al. 1964, Hynes 1970, Beaumont 1975, Hall 1980, Pierce 1980).

Current Velocity

Because river stage was generally lower, current velocities were generally lower in the study area after notching (Tables 3 and 4). Mean velocities for each sampling month ranged from 38 to 54 cm/s in the prenotching year of 1978, and from 15 to 41 cm/s during the postnotching period in 1979 and 1980 {Table 4, Apps. V and W). Wing dam notching and repair appeared to affect current velocities near wing dams 26, 28, 29, and 30 when the effects of changing river stage were removed (Table 5, App. G). Bottom, mean, and surface velocities below the notched portion of dam 26, and bottom 41

Table 2. Mean monthly discharge in thousands entering Pool 13 from Lock and Dam 12, upper Mississippi River, January 1978 through August 1980. Data were obtained from G. E. Johnson, Chief of Hydraulics, U.S. Army Corps of Engineers, Rock Island, Illinois.

1978 1979 1980

Month m3;s ft3/s m3!s ft3/s m3!s ft3/s

January 0.9 32.4 0.6 22.0 0.9 31.3 February 0.7 24.1 0.7 24.0 0.7 25.3

~1arch 1.0 34.9 1.9 66.0 1.4 50.3 April 2.6 92.5 3.9 136.3 2.3 82.2 May 1.7 58.8 3.8 135.7 1.0 34.1 June 1.8 63.2 2.3 80.5 1.9 66.5 July 2.7 94.2 1.8 65.0 0.7 25.1 August 1.3 45.4 1.6 56.1 1.2 41.8 September 1.8 63.0 1.4 49.7 October 1.1 39.9 1.0 34.8 November 0.9 32.1 1.6 54.8 December 0.7 25.1 1.0 34.2 42

Table 3. Current velocity (cm/s) at 0.6 of the depth (mean velocity) at benthos sites (refer to Figures 1 and 2 for locations) and staff gauge readings (m) at Lock and Dam 12, Pool 13, upper Mississippi River, for each sampling month. Three dams were notched in May-July 1979. Velocity information was not obtained at wing dam 26 in June 1979 because the dam was being notched at the time of sampling. Staff gauge readings were obtained from the .u.s. Army Corps of Engineers, Lock and Dam 12, Bellevue, Iowa.

BEFORE NOTCHING Current velocity Staff gauge Date n Mean so Mean so June 1978 27 54 12 2.81 0.33 August 1978 27 48 15 2.62 0.10 September 1978 27 38 14 2.24 0.10 June------1979 23 62 17 3.08 0.10

AFTER NOTCHING Current velocity Staff gauge Date n Mean so Mean so

August 1979 27 31 12 1.98 0.09 October 1979 27 21 11 1.52 0.01 June 1980 27 41 11 2.35 0.05 July 1980 27 15 8 1.27 0.07 43

Table 4. Bottom current velocity (cm/s) at benthos sites in the side channel and at each wing dam before and after notching, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September 1978. Postnotching months were August, October 1979, and June, July 1980. The bottom velocity value from site 30-6-7 in August 1978 was suspected to be erroneous and was not included. 44

Table 4. (continued.) 45

Table 5. Summary comparison of current velocities in the side channel and at each wing dam before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). A + denotes a significant increase, and a - a significant decrease after notching; a 0 denotes no significant difference (App. G).

Site Bottom Velocity Mean Velocity Surface Velocity

Side channel 0 0 0 Wing dam 25 0 0 0 Wing dam 26 + + + Wing dam 28 + + 0 Wing dam 29 0 Wing dam 30 0 0 Wing dam 31 0 0 0 46 and mean velocities below the notched portion of dam 28 increased significantly after notching. Bottom and surface velocities decreased significantly in the vicinity of dam 29 after it was repaired. Surface velocities near dam 30 decreased significantly after notching, possibly due to the repairing of dam 29. Current velocities near wing dams 25 and 31, and in the side channel did not appear to be affected by wing dam modification (Table 5, App. G). No significant differences between prenotching and postnotching current velocities were found below the notch in dam 25, which was "notched" throughout the study; near dam 31; or in the side channel after adjustment for changing river stage.

Substrate

Notching appeared to have little effect on the substrate in the main channel border, but may have increased the amount of sediment entering the side channel. Significant changes in substrate composition after notching were found only at wing dam 31 (increased percent silt-clay) and in the side channel (decreased percent silt-clay, increased percent sand) (Table 6~ App. H). Reduced current velocity after notching at wing dam 31 {Table 4) may have caused the increase in finer sediments (silt-clay) there. In general, the greater the current velocity, the larger the particles that can be swept from the river bed (Leopold et al. 1964, Hynes 1970.) The increase in the proportion of sand in the substrate of the side channel appeared to coincide with notching because it occurred 47

Table 6. Mean percent silt-clay, mean percent sand, and mean percent gravel in the substrate in the side channel and at each wing dam, before and after notching, Pool 13, upper Mississippi River. At notched dams, data for benthos sites 2-8, 3-8, and 4-8, and hydrographic relief site 1-5 were included in the analysis. For unnotched dams, data were included for all benthos and hydrographic relief sites, except hydrographic relief sites 29-1-4, 30-1-4, and 31-1-5 due to missing samples. For the side channel, data were included for all benthos sites; substrate samples were not collected at hydrographic relief sites in the side channel {refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September-October 1978. Postnotching months were August, October 1979, and June, July-August 1980.

49

Figure 9. Mean percent sand in the side channel and at the wing dams for each sampling month, Pool 13, upper Mississippi River. For notched dams, data for benthos sites 2-8, 3-8, and 4-8, and hydrographic relief site 1-5 were included in the analysis. Substrate samples were not collected at wing dam 26 in June 1979 because the dam was being notched. For unnotched dams, data were included for all benthos and hydrographic relief sites, except hydrographic relief sites 30-1-4 in June 1978, 29-1-4 in August 1978, and 31-1-5 in October 1978, due to missing samples. For the side channel, data were included for all benthos sites; substrate samples were not collected at hydrographic relief sites in the side channel (refer to Figures 1 and 2 for locations). Figure 9. (continued.)

Side channel -- Wing dams ---- N = notching

t' I ' I ' I ', I ' ..... I (J"' 0

N

June Aug. Sept.­ June Aug. Oct. June July- Oct. Aug. 1978 1979 1980 51

after the last prenotching sample, September-October 1978 (Fig. 9). It may have been caused by 1) the flushing of sand dislodged from the river bed during notch construction into the side channel, a temporary effect; or 2) removing obstructions (sections of wing dams 26 and 28) to the normal bed load and lower part of the suspended load, thereby causing a long-term increase in the amount of sand, and possibly the total amount of sediment, entering the side channel; or 3) both. Most of the sand moved by the current is carried in the bed load or in the suspended load near the river bed (Morisawa 1968, Simons et al. 1975), whereas silt-clay is more uniformly distributed throughout the water column (Simons et al. 1975). The increased proportion of sand in the substrate of the side channel after notching persisted to the end of the study (Fig. 9); hence, it may not be a temporary phenomenon. A long-term increase in sediment deposition in the side channel would, of course, shorten its life.

Temperature and Dissolved Oxygen

Temperature and dissolved oxygen concentration did not appear to be affected by notching (Fig. 10). Both varied little with depth but varied greatly between sampling periods (Fig. 10, Apps. V and W). Maximum ranges from surface to bottom were 0.6°C for temperature and 1.2 mg/1 for dissolved oxygen in 1978, and 0.5°C for temperature and 0.8 mg/1 for dissolved oxygen in 1979. Temperature and dissolved oxygen data for June and July-August 1980 were not included because 52

Figure 10. Mean temperature (A) and dissolved oxygen concentration (B) at benthos and hydrographic relief sites for each sampling month in 1978 and 1979, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Vertical lines represent ranges. Temperature and dissolved oxygen information at wing dam 26 in June 1979 was not obtained because the dam was being notched. Data for June and July-August 1980 were not included because the meter was malfunctioning during those sampling periods. N = notching. 53

~ u 0

0") C'l :;:, ...... c:x:: C'l .-I

Q) !::: :;:, '-:>

0 0 . 0 . 0 . 0 . . 0 co ~ o::t N .-I ( Lf5w) uon-e •.q.ua:>uo::> ua5A"xo paA Lass ~o

. ~ . c..~ Q) u tl) 0

Q) !::: :;:, '-:> 0 0 0 0 0 . . . . . 0 LO 0 LO 0 .-I .-I M N N

( '"',Jo ) a..tn.,-e..tadwal... 54 the meter was malfunctioning during those sampling periods. Highest mean temperatures occurred in summer, 22.9°C in August 1978 and 25.9°C in August 1979; lowest mean temperatures recorded in the sampling months occurred in fall, 15.9°C in September-October 1978 and 16.7°C in October 1979 (Fig. 10,A). Highest mean dissolved oxygen concentrations occurred in fall, 7.9 mg/1 in September-October 1978 and 8.2 mg/1 in October 1979; lowest mean dissolved oxygen concentrations were in spring, 5.8 mg/1 in June 1978 and 6.6 mg/1 in June 1979 (Fig. 10,B). Oxygen levels appeared to be adequate for warmwater fish populations because dissolved oxygen concentrations were predominantly greater than 5.0 mg/1 (Whitmore et al. 1960, Doudoroff and Shumway 1967, Bennett 1970, EPA 1973, Hall 1980, Pierce 1980) (Fig. 10,8). However, dissolved oxygen concentrations were not measured just before dawn when levels might have been lower.

Benthos

Abundance and Species Diversity

Notching probably had little effect on benthic invertebrate populations in the main channel border, but may have been more influential for benthos in the side channel. Benthos populations in the main channel border generally increased significantly from the_prenotching to postnotching periods (Table 7, App. I). The increases were probably due to unusually high water levels and scouring in July 1978 (prenotching period) resulting in low benthic 55

Table 7. Benthic invertebrate density (No.) and biomass (g) per m2 , and number of taxa collected with a 252-cm2 Ponar grab, in the side channel and at each wing dam, before and after notching, Pool 13, upper Mississippi River. For notched dams, data for benthos sites 2-8, 3-8, and 4-8 were included in the analysis. For unnotched dams and the side channel, data were included for all benthos sites (refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September 1978. Postnotching months were August, October 1979, and June 1980. July 1980 data were not included to balance seasonal differences as explained in the text. Table 7. (continued.)

BEFORE NOTCHING Density --- Biomass Taxa Site n Median Mean so n Median Mean so n Median Mean so Side channel 27 357 942 1139 27 1.07 6.18 11.03 9 6.0 6.1 4.0 Wing dam 25 27 1865 1936 1300 27 24.17 29.90 32.30 9 7.0 6.3 2.5 Wing dam 26 27 159 420 669 27 0.16 0.90 1.40 9 3.0 3.7 1.3 Wing dam 28 27 79 135 150 27 0.12 0.65 1.62 9 3.0 2.3 1.5 Wing dam 29 36 218 670 1910 36 0.28 6.42 25.68 12 4.5 4.1 2.0 Wing dam 30 36 79. 305 412 36 0.12 1.63 4.60 12 2.5 2.9 2.0 Wing dam 31 36 119 5197 13346 36 0.20 12.13 28.95 12 4.0 4.4 3.3

(J1 m AFTER NOfCHING Density Biomass Taxa Site n Median Mean SD n Median Mean so n Median Mean so Side channel 27 873 1509 1735 27 1.15 4.32 5.62 9 6.0 6.6 3.8 W1nfJ dam 25 24 1409 2232 1823 24 6.51 9.84 10.07 8 7.5 8.0 3.5 Wing dam 26a 27 1548 8422 16727 27 2.50 11.24 20.30 9 5.0 6.1 3.0 Wing dam zsa 27 437 1108 2175 27 0.48 1.46 2.92 9 5.0 ,4.7 1.9 Wing dam zgb 36 1250 1755 2793 36 2.54 8. 74 16.40 12 5.0 5.3 1.9 Wing dam 30a 36 1944 3428 5957 36 1.81 22.64 63.48 12 6.0 7.3 4.0 liinq dam 3la 36 1369 3395 3933 36 2.32 4.93 5.71 12 6.5 6.6 2.6 ·------· aoens1ty. biomass. and number of taxa were significantly greater after notching (App. I). boensity and biomass were significantly greater after notching (App. I). 57 densities, and recovery in postnotching 1979 and 1980. Benthic densities (No./m2) generally decreased from June to August 1978 (Fig. 11), and Hall (1980) concluded that the peak annual discharge that occurred in July 1978 (Table 2) probably caused the decrease by some combination of 1) reducing percentages of productive substrate (silt-clay), 2) dislodging invertebrates and moving them downstream, and 3) stimulating hyporheic or lateral movement of invertebrates to avoid being dislodged. These decreases occurred at all locations except wing dam 25 and were significant except in the side channel and at wing dam 31 (Fig. 11, App. J). Other than dam 25, densities at all locations in 1978 remained low in the fall except at dam 31 where large numbers of Trichoptera were found in substrate with high gravel content (Fig. 11, Apps. J, X, and Z). At wing dam 25 in 1978, benthic densities increased significantly from spring to summer and fall (Fig. 11, App. J). The prenotching pattern of seasonal fluctuation in benthic density at dam 25 followed the general pattern described by Hynes (1970), i.e. in a typical temperate stream, benthic densities are lowest in late spring due to winter mortality and insect emergence, and then, as eggs hatch and early instars are recruited, densities increase in summer to a peak in fall. Benthos populations at dam 25 may have been protected from the flushing effects of the spate in July 1978 because dam 25 was on the downstream inside of a river bend in an area of reduced current velocity (Fig. 1, Table 4). Benthos populations became reestablished during the postnotching years of 1979 and 1980, and seasonal fluctuations in benthic densities 58

Figure 11. Mean benthic invertebrate density (No.) and biomass (g) per m2 collected with a 252-cm2 Ponar grab in the side channel and at each wing dam for each sampling month, Pool 13, upper Mississippi River. For notched dams, data from benthos sites 2-8, 3-8, and 4-8 were included in the analysis. For unnotched dams and the side channel, data from all benthos sites were included. Benthic invertebrate samples were not collected at wing dam 26 in June 1979 because the dam was being notched (refer to Figures 1 and 2 for locations). 59

r-1 . I M 0 SIDE CHANNEL I r-1 0 r-1::< 10.0 ::<- N -I 7.5 N E - IE b'l -- 5.0 - 1-l+.J ~-&·.-1 2.5 - ___... z~ -· !------~----- 1---·-·------fa fa I I I I I I I I I I I I I I I I ------I I I I I I I I I I I I ~~ June Aug. Sept. June Aug. Oct. June July

1978 1979 1980

r-1 I ·WING .DAM 25 M 0 I.-I 0 r-1::< ::<- -~ 7.5 N E 1 ...... s Ol 5.0

June Aug. Sept. June Aug. Oct. June July

1978 1979 1980

Figure 11. (continued.) 60

...-! WJN; I DAM 26 0 ...-! 30.0 ::< N- le tJ'l - 25.0 +J -& ·r-l ~ fa 20.0 ~

15.0

('t) I 0 .-I 10.0 ::< N- le- ~ 5.0 ~ e ~ I June Aug. · Sept. June Aug. Oct. June July 1978 1979 1980

Figure 11. (continued.) 61

~DAM 28

June Aug. Sept. Jl.U'le Aug. Oct. Jl.U'le July 1978 1979 1980

~DAM 29

>< N- N- 'e 7.5 -'e -tTa +J 5.0 ...... ~ j i 2.5 fa ~ i June Aug. Sept. June Aug. Oct. Jl.U'le July 1978 1979 1980

Figure 11. (continued.) 62

,..., I MO I,..., WING DAM 30 ~:< 10.0 x­N -I N E Is-- tr~ 7.5 5.0 ------·

2.5

June Aug. Sept. June Aug. Oct. June July 1978 1979 1980

WING DAM 31 lO.O

,..., 15.0 I M 0 I ,..., ,...,:<0 x- N 10.0 N-•s •s-- 0'1 5.0 z&j! jj

. June Aug. Sept. June Aug • Oct. June July 1978 1979 1980

Figure 11. (continued.) 63 then fo 11 owed the genera 1 pattern described by Hynes ( 1970), with densities increasing from spring to summer and fall at all locations (Fig. 11). The increases were significant except for the side channel and wing dam 29 in 1979 (App. j). Benthic biomass (g/m2) also was reduced in 1978, probably by the spate in July, and then recovered during the postnotching period. In 1978 benthic biomass decreased significantly from June to August or September at all locations except the side channel and wing dam 26, where the changes in biomass were not significant (Fig. 11, App. K). In 1979 benthic biomass increased significantly between spring and fall sampling periods at all locations except the side channel, wing dam 28, and wing dam 29, where the changes in biomass were not significant (Fig. 11, App. K). Benthic density and biomass in the main channel border were significantly greater after notching at all wing dams, except dam 25 where the differences were not significant (Table 7, App. I). At each dam where there were significant postnotching increases, benthos populations had been reduced in 1978, probably by the high summer discharge. At wing dam 25, where benthic densities and biomass did not change significantly after notching, benthos populations were not reduced in 1978. Number of benthic invertebrate taxa was significantly greater after notching at all wing dams except dams 25 and 29 (Table 7, App. I). These increases, too, were probably caused by reductions in numbers of benthic taxa in 1978, and recovery in 1979 and 1980. There was evidence of localized effects of notching on benthos 64 in the main channel border. High gravel content, and, therefore, high densities and biomass of benthic invertebrates, particularly Trichoptera, (Hall 1980) below the notch in wing dam 26 in the fall of 1979 may have been an effect of increased flow caused by notching. Exposure of gravel in the study area, as occurred below the notch in dam 26 in 1979, generally corresponded to dramatic increases in Trichoptera populations in fall. The first, second, and third highest benthic densities during the study were found at dam 26 in October 1979 (22,700/m2), at dam 31 in September 1978 (15,300/m2), and at dam 30 in October 1979 (6,200/m2), respectively (Fig. 11, App. Z). Those three peaks in abundance were caused primarily by large numbers of Trichoptera, and were associated with the third (7.9%), first (24.7%), and second (11.7%) highest percentages, respectively, of gravel found in the substrate during the two fall sampling periods (App. X). Relatively high benthic biomass was associated with those peaks in abundance, as well (Fig. 11, App. Z). Benthic densities, biomass, and number of taxa in the side channel did not change significantly after notching (Table 7, App. I) even though fluctuations in benthic densities followed the typical pattern described by Hynes (1970) during the postnotching period. Benthos populations in the side channel (as well as in the main channel border) appeared to be negatively affected by the high summer discharge in 1978 because densities decreased, although not significantly, from June to August that year (Fig. 11, App. J). Benthos populations then seemed to recover somewhat in 1979; densities increased from spring to summer and fall that year, although the 65 increases were not significant (Fig. 11, App. J). The lack of significant increases in benthic densities, biomass, and number of taxa from the prenotching to postnotching periods in the side channel may have been caused by the significant decrease in percent silt-clay and significant increase in percent sand which appeared to coincide with notching (previous subsection). In the prenotching phase of the study, Hall (1980) found that benthic invertebrate density, biomass, and number of taxa were positively, significantly related to percent silt-clay, and negatively, significantly related to percent sand in the predominantly sandy substrate. His findings confirmed the conclusions of others that sand is a poor substrate for benthic invertebrates (e.g. Pennak and Van Gerpen 1947, Sprules 1947, Cordone and Kelley 1961, Chutter 1969, Hynes 1970, Schmal and Sanders 1978).

Taxonomic Composition

Aquatic macroinvertebrates from 4 phyla, 8 classes, 16 orders, 41 families, and 51 genera were identified during the two phases of the study (App~ B). Changes in taxonomic composition after notching probably were caused primarily by recovery of populations ·of Chironomidae (Diptera) and Potamyia flava (Hagen) (Trichoptera: Hydropsychidae) in 1979 and 1980 after they had been reduced by high summer discharge in 1978. Taxonomic composition was analyzed with data from benthos sites 31-5-7 and 31-5-8 in September 1978, and 26-2-8, 26-3-8, 26-4-8, and 30-5-8 in October 1979 eliminated because those sites 66

had atypically high Trichoptera and Chironomidae densities and gravel content (Fig. 2, App. Z). Hall (1980) felt th~t inclusion 6f such sites would indicate that Diptera and Trichoptera dominated the benthos in the study area, whereas, they did not during the prenotching phase of the study. Before notching, Oligochaeta was the dominant taxon in the predominantly sandy substrate (Table 8, App. Z). During the postnotching period, however, Diptera, especially Chironomidae (92% of postnotching Diptera density), and Trichoptera, especially Potamyia flava (82% of postnotching caddisfly density), were found to dominate benthic invertebrate density in the predominantly sandy substrate (Table 8, App. Z). The increase in the percentages of Diptera and Trichoptera, and the decrease in the percentages of Oligochaeta and Ephemeroptera after notching were caused primarily by the increase in densities of Diptera and Trichoptera after notching (Table 8, App. Z). Effects of the high discharge in July 1978 on the four groups may have differed because of differences in timing of insect emergence (in relation to the spate), or to differences in ability to avoid heavy currents, or both. Chironomidae and Potamyia flava should have been'emerging and ovipositing in July (Fremling 1960, Oliver 1971), and the spate in July may have reduced their reproductive success

and population densities for that year. Oligochaeta and Hexagenia ~P· (Ephemeridae), the dominant mayfly, are adapted for burrowing and may have been able to escape the flushing effects of the high discharge better than Chironomidae and Potamyia flava. 67

Table 8. Mean density (No.} per m2 and percent of total benthic invertebrate density for major taxa before and after notching, Pool 13, upper Mississippi River. Mean densities were estimated by multiplying prenotching and postnotching total benthic invertebrate density (App. F) by percent composition for the respective taxa before and after notching. Prenotching months were June, August, and September 1978. Postnotching months were August, October 1979, and June 1980. July 1980 data were not included to balance seasonal differences as explained in the text. Data from benthos sites 31-5-7 and 31-5-8 in September 1978, and 26-2-8, 26-3-8, 26-4-8, and 30-5-8 in October 1979 were not included because of high Diptera and Trichoptera densities and gravel content {refer to Figures 1 and 2 for locations}.

Mean Density Percent

Taxon Before After Before Aft~r

01 igochaeta 362 234 51 12 Diptera 127 1124 18 57 Trichoptera 54 394 8 20 Ephemeroptera 151 191 21 10 Other 18 26 3 1 68

Benthic invertebrate biomass was dominated by Hexagenia sp. both before and after notching (App. Z). Ephemeroptera comprised 65.0% of benthic biomass before notching and 65.2% after notching, with Hexagenia sp. representing 98.7% of mayfly biomass both before and after notching.

Macroinvertebrate Aufwuchs

Density and biomass of macroinvertebrate aufwuchs in combined· basket and multiple-plate artificial substrate samples did not appear to change after notching. Prenotching and postnotching density and biomass were not significantly different for all dams or for unnotched dams (Table 9}. Small sample size precluded statistical comparisons of prenotching and postnotching artificial substrate samples from notched wing dams. Hydropsychidae (Trichoptera) dominated macroinvertebrate aufwuchs in combined basket and multiple-plate samples, comprising about 90% of numbers both before and after notching, and about 90% of biomass before and 96% of biomass after notching. Potamyia flava was the most important colonizer in the combined samples after notching, representing 65% of total numbers and 73% of total biomass. Before notching, both Potamyia flava and Cheu~osyche sp. were n1ajor colonizers, each constituting about 30% of numbers and 35% of biomass. A detrimental effect of wing dam notching may be the removal of productive substrate (wing dam rock) for aquatic organisms. The wing dams were islands of rock in a sea of sand. The artificial substrates on the dams were colonized much more heavily by 69

Table 9. Macroinvertebrate aufwuchs combined densitya (No.) and biomassb (g) per m2 from basket and multiple-plate artificial substrates, Pool 13, upper Mississippi River (refer to Figure 1 for locations). There was no significant difference between prenotching and postnotching density (Wilcoxon paired-sample test,

T = 18.0, n = 7, 0.40 < £. <0.60) and between prenotching and postnotching biomass (Wilcoxon paired-sample test,

T = 20.0, n = 7, 0.20 <.2. <0.40) for all dams; and no significant difference between prenotching and postnotching density (Mann-Whitney test, U = 12.0, n1 = n2 = 4, £.>0.20) and between prenotching and postnotching biomass (Mann-Whitney test, U = 11.0, n1 = n2 = 4, £. :>0.20) for unnotched dams. Table 9. (continued.)

Density Biomass Orientationd Wing dam Sample sitec on wing dam Prenotch Postnotch Prenotch Postnotch

25 6 7 8,025 8,405 40.0 52.7 26 6 7 661 11,838 5.1 81.4 26 6 8 23,099 2,937 133.5 16.2 29 5 7 16,430 8,335 57.0 45.5

29 5 8 2,974 23,018 19.5 149.7 -....! 30 5 7 30,828 33,732 165.1 157.3 0 30 5 8 20,069 31,552 62.7 191.8

acombined density = (number of organisms on basket sampler + number of organisms on multiple-plate sampler) X (10,000 cm2;m2)/(surface area of basket sampler( = 1,767 cm2) + surface area of multiple-plate sampler( = 940 cm2)). bcombined biomass = (weight of organisms on basket sampler + weight of organisms on multiple-plate sampler) X (10,000 cm2;m2); (1,767 cm2 + 940 cm2).

cSample site: 5 = inside transect, 6 = outside transect. dbrien~ation on wing dam: 7 = upstream, 8 = downstream. 71 macroinvertebrates than the river bed, which was predominantly sand and was sampled with a Ponar grab. When compared with Ponar samples collected in September 1978 and October 1979, the months when artificial substrates were retrieved, artificial substrate samples had about 5 times more macroinvertebrate numbers and 6 times more biomass before notching, and about 3 times more numbers and 10 times more biomass after notching per square meter than the Ponar samples (Table 9, App. F). Several authors have considered Potamyia flava, the dominant colonizer of the artificial substrates, to be an important food for fish in the Mississippi River (Carlander et al. 1959, Hoopes 1960, Jude 1968, Ranthum 1969, Bur 1976, Pierce 1980).

Fish

There was no appreciable effect of wing dam notching on fish populations, as indicated by catch per unit effort of all species combined and of selected species in electrofishing, hoop net, and seine catches before and after notching. The only apparent effect of wing dam modification on catches of fish was a significant increase in electrofishing catches at wing dam 25, which may have been caused by addition of rock to the dam. The few remaining significant differences between prenotching and postnotching fish catches did not appear to follow a consistent trend that would indicate an effect of notching on fish populations. A total of 57 comparisons were made of prenotching and postnotching electrofishing catch per unit effort (No./30 min) of all species combined and of selected species, with and without 72 adjustment for changing river stage (Tables 10 and 11; Apps. L, M, N, and Q). For prenotching and postnotching electrofishing catches of all species, a significant difference was found in only 2 of 9 comparisons. Those differences were increases in total catch per unit effort at shoreline and outside transects at wing dam 25 (Table 10, App. l). For electrofishing catches of the six selected species, a significant difference in catch per unit effort occurred in 6 of 48 comparisons. Those differences were increases in catches of freshwater drum and carp at outside transects at wing dam 25, and of freshwater drum at all shoreline transects adjacent to wing dams and in the side channel (Tables 10 and 11; Apps~ M, N, and Q). The postnotching increase in electrofishing catches at dam 25 may have been caused by the addition of new rock to the dam adjacent to the notch, making it more susceptible to electrofishing and possibly providing additional cover for fish. The postnotching increase in electrofishing catches of freshwater drum at shoreline transects appeared to be a general phenomenon throughout the study area, and, therefore, was most likely not an effect of wing dam modification. Age determination from scales of 297 freshwater drum showed catches of drum to be dominated by young-of-the-year and age I fish both before (Pierce 1980) and after notching. A total of 48 comparisons were made of prenotching and postnotching unbaited and baited hoop net catch per unit effort (No./24 h) of all species combined and of selected species (Table 12; Apps. 0, P, R, and S). For prenotching and postnotching catches jn unbaited hoop nets, a significant difference was found in only 2 of 73

Table 10. Summary comparison of electrofishing catch per unit effort for all species combined and for freshwater drum, sauger, and carp before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). A + denotes a significant increase after notching; a 0 denotes no significant difference (Apps. Land M). N/A indicates that the regression of catch per unit effort on staff gauge level after notching was not significant, or that sample

size was too low (n ~6) for Wilcoxon testing after omission of zero differences between matched values (Conover 1971). 74

Table 10. (continued.)

All Freshwater Site Species Drum Sauger Carp

Side channel CE & CW combined 0 + N/A N/A

Wing dam 25 25-lS + + N/A N/A 25-A & 25-B combined + + N/A N/A

Emergent wing dams 26-lS & 28-lS combined 0 + 0 0 26-A & 28-A combined 0 0 N/A 0 26-8 & 28-B combined 0 0 0 0 26-C & 28-C combined 0 N/A N/A N/A

Unnotched wing dams

29-1$, 30-1S, & 31-lS combined 0 + 0 N/A

29-A, B, & C; 30-A, B, & C;

and 31-A, B, & C combined 0 N/A N/A N/A 75

Table 11. Summary comparison of electrofishing catch per unit effort for selected species before and after notching, without adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). A + denotes a significant increase after notching; a 0 denotes no significant difference. Median and mean catch per unit effort for each species are included in Appendix N; Mann-Whitney test statistics are reported in Appendix Q. N/A indicates that prenotching and postnotching catch per unit effort were compared after adjustment for changing river stage (Table 10) or that fewer than 3 fish were caught. Table 11. (continued.)

Freshwater Shorthead Site Drum Sauger Carp Bl uegi 11 Redhorse Quill back

Side channel

CE & CW combined N/A 0 0 0 0 0

Wing dam 25

25-15 N/A 0 0 0 0 0

N/A + 0 25-A & 25-B combined N/A N/A N/A -....J "' Emergent wing dams

26-lS & 28-1$ combined N/A N/A N/A 0 0 0

26-A & 28-A combined N/A 0 N/A 0 0 0

26-B & 28-B combined N/A N/A N/A 0 0 0

26-C & 28-C combined 0 0 0 0 0 0

Unnotched wing dams

29-1S, 30-lS, & 31-lS combined N/A N/A 0 0 0 0

29-A, B, & C; 30-A, 8, & C;

and 31-A, B, & C combined 0 N/A 0 N/A 0 N/A 77

Table 12. Summary comparison of catch per unit effort before and after notching for all species combined and for selected species in unbaited and baited hoop nets, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). A + denotes a significant increase, and a - a significant decrease after notching; a 0 denotes no significant difference. Median and mean catch per unit effort for all species combined are included in Appendix 0, and for selected species in Appendix P. Mann-Whitney test statistics are reported in Appendix R for all species combined, and in Appendix S for selected species. Table 12. (continued.)

UNBAITED

A"ll Small mouth Freshwater Channel Flathead Site Species Carp Buffalo Drum Catfish Catfish

Side channel 0 0 0 0 0 0

Wing dam 25 0 0 0 0 0 +

Emergent wing dams 0 0 0 0 0 0

Unnotched wing dams 0 0 0 0 + 0

co'-.1 BAITED

All Small mouth Freshwater Channel Flathead Site Species Carp Buffalo Drum Catfish Catfish

Side channel 0 0 0 .,.. 0

Wing dam 25 0 0 0 0 0 0

Emergent wing dams 0 0 0 0 0 0

Unnotched wing dams 0 0 0 0 0 0 79

24 comparisons. Those differences were increases in catches of flathead catfish at wing dam 25 and of channel catfish at unnotched wing dams (Table 12; Apps. P and S). For catches in baited hoop nets, a significant difference was also found in 2 of 24 comparisons. Those differences were decreases in catches of all species combined and of channel catfish in the side channel (Table 12; Apps. 0, P, R, and S). There was no significant difference between prenotching and postnotching catch per unit effort in seine hauls (Table 13). 80

Table 13. Mean catch per unit effort (No./haul) for major families of fishes in seine catches before and after notching in the side channel, Pool 13, upper Mississippi River (refer to Figures 1 and 6 for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. No significant difference was found between prenotching and postnotching catch per unit effort (Wilcoxon paired-sample test: n = 7, T = 25, 0.05<£<0.10).

Before After

Family n Mean so Mean so

Cyprinidae 3 19.7 17.1 7.6 6.1 Ictaluridae 3 3.6 5.8 0.4 0.5 Percidae 3 3.3 2.7 1.6 0.4 Catostomidae 3 1.2 0.2 0.3 0.3 a Percichthyidae 3 0.5 0.3 2.7 3.5 Centrarchidae 3 13.7 19.1 3.1 3.8 sc1aem . .d ae b 3 6.0 4.1 0.5 0.8 aConsisted of a single species, white bass (Morone chrysops). bconsisted of a single species, freshwater drum (Aplodinotus grunniens). 81

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Appendix A-1. Depth profiles along three hydrographic relief transects across wing dam 25 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although the location of transects varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). 89

;:c:. ~------~---215 m------~ "'0 "'0 ~------150 m C1) ::s ~------90 m- ----~ ...... c.. X ;:c:...... I ...... () 0 ::s rt..... ::s s:: C1) c..

::e:..... ::s 3 lC mo- 0 ...... Ill ;- 3 ..CA N U'l -·~

c... s:: ::s C1)

10 meters 90

LO C\J E res 0 C'l .,...s::: 3

.,... +l s::: 0 u

...... I o::( .,...X "'0 s::: Q) c.. c.. o::( 91

)> "C "C ro ::::1 ...... 0.. X )> I ......

-(") 0 ::::1 ...... c-t ::::1 c ro 0..

N U'l

0 (") M­e C"' ro -s 92

1.0 N E m a en .,....c: :::;:

""0 Q) ~ ...... c: -1-> c: 0 ...... u

...... , c::cI .,....X ""0 c: Q) c.. c.. c::c ,.. 93

(') -0 ::3 .....rl- ::3 c (I) 0..

:;::.....

I-' 1.0 ...... 1.0 94

~

,....._0'1

I 0'1 ~I .-I s... QJ ..0 ~ 0 of-) ~ u I 0 I 'I

LO N ~ E ttl Cl O'l .....s::::: 3: tl l I " .--... "0 QJ ;:, .....s::::: of-) s::::: 0 u . .-I I c:C .....X "0 s::::: QJ c.. c.. c:C .....__ ,... • 95

)::> "'C "'C (!) ::::5 ...... c.. X )::> I ...... (') 0 ::::5 ...... c-1- ::::5 1:: (!) c..

:;;::...... ::::5 c.a 0 Q,l 3 N <.11

c... 1:: ::::5 (!) ...... co\.0 0 96

1.0 N E t1j Cl

C'l .....s:: 3:

-o ClJ :::::s s:: .._, s:: 0 u

...... t I c::( .....X -o s:: ClJ 0.. 0.. c::( 97

Appendix A-2. Depth profiles along three hydrographic relief transects across wing dam 26 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although the location of transects varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). Hydrographic relief information was not obtained in June 1979 because the dam was being notched. 98

~------W 09~~=------""""1"""------W OLL ~ I· w SOL :-..' ~ T "t ~ ~ ' " ! ~ i ' I ' ~~ ~ C'l' ' '~ El !\. cl cl -t I I ~ ..... m .,., 3 ·-Ic ·~g_ ~: .:.::"­ I ~ I i' I I i '~ ~, . ' "'0 (]) :'-' :;::, r-...... s:: ~ +-' s:: 1-­ 0 , u . ' N I '~ c:( .....X "~ "'0 ! s:: (]) I' c.. c.. 0 10 c:( meters 99

)> "'C "'C (1) ::s c.. --'• X )> I N

n T 0 ::s I ("'!- --'· ::s c (1) " c.. . '•" - " j l

.....:;;:

0 Ill 3 N 0'1 100

s... (]) .0 0 -!-) u 0

.,.... 3:

-a (]) :::s ' s:: .!-) s:: 0 u ......

.,....X -a s::: (]) c.. c.. c:(

t " 101

):::o "'0 "'0 C'D ::I ...... 0. >< ):::o I N ...... n 0 ::I rt...... ::I s:: C'D 0. 102

s... Q) ..c 0 +-l u 0

•r- 3

. "'C Q) ::3 s:::: +-' s:::: 0 u . N c:r:I ,... X "'C s:::: Q) c.. c.. c:r: 103

)> "'0 "'0 m ::I ...... c.. >< )> I N ...... (") 0 ::I cT...... ::I s:: m c..

::e::...... ::I <.C ~ 3 N 0'1

c... s:: ::I m ...... 1.0co 0 104

0 00 ~ "'..-t k +-> I Vl !\ :::::! O'l ~ c:c:::::! 1'- t I ' ~ 1.0 !\ N E 'jo.. ttl Cl 1' O'l ~ .....s:: 3 "'t I I ' I '~ I -~ I I '~ ~ . "'0 Q) I :::::! t s:: -1-l s:: 0 ..._,u . N c:cI .....X "'0 s:: Q) 0. c:c0. 105

Appendix A-3. Depth profiles along three hydrographic relief transects across wing dam 28 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the

I Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although the location of transects varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). 106

'

co N E c"' .,. 0) c .. •r- :s: ".!~GJ E ·-~

'"0 Q) ::3 c •r- +-> c 0 u

(V) c:r:I X •r- '"0 c Q) 0. c:r:0. 107

..... >< ):::o I w

(') 0 :::s _,,rt :::s s::: (!) 0..

::I (.Q 0 Ql 3

I'\) 00

):::o s::: (.Q s::: Vl c-1- ...... 1.0 ...... 00 108

~ Q) .0 0 +-> u 0

CX) N E ata C'l .....s::: 3:

"0 Q) :::::! s::: +> s::: 0 u

CV) I c:( .....X "0 s::: Q)c.. c.. c:( 109

> "'C "'C (1) :::3 .....0. >< > I w

::e:..... :::3 1.0 0 Q.J 3 N 00 110

. "'0 Q) ::I ...... s::: -!-> s::: 0 ...... u

M I <( ...... X "'0 s::: Q) a. a. <( 111

;:c:. "0 "0 ro :::s .....0. ---1 X ;:c:. I w ...... (") 0 :::s .....rt :::s c ro 0......

:e:.....

0 (") rt 0 0"' ro ~ 112

co N E ItS Cl O'l s::: •r- 3:

"0 (J) ::::! s::: •r- ~ s::: 0 u

M c:r:I X •r- "0 s::: (J) c. c. c:r: 113

)> "0 "0 CD ::5 c.. X )> I w

() 0 ::5 r+ ::5 c: CD c..

:e::...... ::5 1.0 0 Ill 3 N 00

...... I.D 00 0 114

Appendix A-4. Depth profiles along three hydrographic relief transects across wing dam 29 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although the location of transects varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). 115

-6" 215 m "'C Cl) 140 m ::I 60 m ---i ...... 0.. X )::o I ~ n -0 ::I M-...... ::I c: Cl) 0..

...... :e:: ::I (.Q c Ill 3 N c \.0 Q 3 .._, c... ..0 c: ::I Cl) ...... \.0 ...... 00

6 Jb meters 116

.j..) Vl ::::5 O'l ::::5 c(

"0 Q) ::::5 ....s:: .j..) s:: 0 u

<:T I c( X "0 s:: Q) c. c. c( 117

(

):::o "'0 "'0 (1) ::::s 0...... X ):::o I ..,::..

(') 0 ::::s M-.... ::::s c (1) 0..

....:::0::

0 (') rT 0 0" (1) -s 118

•r- +-> s:::: 0 u

•r- "'C s:::: Q) c.. c..

..... X ::J;::o I ..j:::o ...... n 0 ::::1 .....c-T ::::1 s::: Cl) 0.

.....:::e: ::::1 tO 0 Q,l 3 N \.0

::J;::o s::: tO s::: VI c-T ..... \.0 ...... \.0 120

s.. Q) ..0 .....,0 u 0

0'\ N E 10 0

0') .,....s::

"0 Q) :::::1 s:: .,...... , s:: 0 u

o:::t I c:( X "0 s:: Q) c.. c.. c:( 121

)> -o -o (I) ::s __, .....0.. X )> I .-!:=>

(") 0 ::s rt..... ::s s::: (I) 0..

:E.....

c... s::: ::s (I) ...... co\.0 0 122

.,.... ::;;:

.,.... +-' s:: 0 u

<:::1" I c:( >< "'C s:: Q) c.. c.. c:( 123

Appendix A-5. Depth profiles along three hydrographic relief transects across wing dam 30 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all

months, although the location of transect~ varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). 124

SJ919W QL Q

I ...... CX) 0'1 . ~ .--i ol Q) CW)I I s::: ~ "'J ~

.-..,.CD~1 ..aG;. 0 (V) E ~I E! ra ·-I Cl O'l ~~ s::: I •.- I 3

. "'0 Q) s:::~ •.- +-l s::: 0 u

L() I c:( X •.- "'0 s::: Q) 0.. 0.. c:( 125

)::> "'0 "'0 ro ::s 0.. X )::> I U1

...... (") 0 ::s M-...... ::s s::: ro 0..

...... ::s tO 0 Ql 3 w 0

...... 1.0...... ex:> 126

s... QJ .0 0 +-> u 0

0 (V) E res a 0') s:: •r-

L!'l c::r:I X •r- "0 s:: QJ 0.. 0.. c::r: 127

"~-----c:: --t ..... X )::1 I (J"J

...... () 0 :;:, c-t :;:, s:::: (I) c..

..... ~ 1.0 0 Ill 3 w 0

• 128

•r- +J !:: 0 u

Ln ex:I X •r- 129

)> -c -c C1) :::s ...... 0.. X )> I <.T1

(') 0 :::s ...... cT :::s !:: C1) 0..

:E:...... :::s tO 0 Cl 3 w 0

0 (') cT 0 C" C1) -s 130

0 00 0"1 ......

0 (V) E ttl 0 O'l s::

.,.... +l s:: 0 ...... u

l.() I o::x: .,....X "'0 s:: QJ c. c. o::x: 131

)> "'C "'C (I) ::s ...... 0.. X )> I U1 ...... () 0 ::s cT...... ::s s:: (I) 0..

...... ::e:: ::s tO 0 ~ 3 w 0

...... 1.0 00 0 132

Appendix A-6. Depth profiles along three hydrographic relief transects across wing dam 31 during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Distances from the Illinois bank and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although the location of transects varied somewhat due to variability in range finder use. Vertical columns indicate the approximate position of the wing dam. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). 133

215m 60 m~40 m

...-... (') 0 ~ rt...... ~ c:: CD .0.

:E:...... ~ tO g· Cl SlJ 3 F. w ......

c... c:: ~ CD

6 134

.,.... 3

.,...... , t: 0 u

\.0 c:c:I .,....X "'0 t: Q) 0.. c:c:0.. 135

X ):::o I 0'1

(') 0 ::;:, ...... c-t ::;:, c: (I) 0..

...... :::;;: ::;:, tO 0 Cl 3 w ......

0 (') c-t 0 o­ (1) """S 136

"'0 (]) ::::5 .,....!:: +J !:: 0 u

~ I c::( .,....X "'0 !:: (]) 0. 0. c::( 137

...... X )::o I (J)

(') -0 :::3 rt...... :::3 c C1) 0..

:;;:...... :::3 (,Q a Ql 3 w ...... 138

s.... Q) .0 0 +-> u 0

.-1 M E Cl"' C'l .,....s:: ::::;;:

"'0 Q) :::::s .,....s:: +-> s:: 0 u

1.0 I c:c .,....X "'0 s:: Q) 0. 0. c:c 139

)::> "'C "'C C1) ::::5 ...... c.. X )::> I 0\ n 0 ::::5 ...... c-T ::::5 s:::: C1) c..

...... ::::5 I.C c llJ 3 w ......

c... s:::: ::::5 C1) ...... 1.0co 0 140

..-t M E n:s Cl 01 s::: •r- 3:

-a QJ ::I s::: •r- .J-) s::: 0 u

I.D I c:( X ·.- -a s::: QJ c.. c.. c:( 141

Appendix A-7. Depth profiles along three hydrographic relief transects across the side channel during each sampling month, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). Transect locations and vertical and horizontal scales are labeled for June 1978 and are the same for all months, although recorded transect lengths varied somewhat due to variability in range finder use and river stage. Transects were approximately 800, 400, and 70 meters from the lower opening of the side channel. Depth readings in each month were adjusted to a constant river stage (staff gauge level = 2.32 m). Side Channel

.. Upper Chute . · •

Middle Chute

'------· 100 . meters

Appendix A-7. (continued.) Side Channel June 1978 143

)> "'C "'C 1'1) :::::1 ....0.. X )> I -....!

(") 0 :::::1 ....cT :::::1 s::: 1'1) -0..

....(/) 0.. 1'1)

(""') :::::1" Ill :::::1 :::::1 1'1)......

)> s::: I.C s::: Vl cT 144

s... Q) ..c 0 of-) u 0

...... Q) s::: s::: ..c:-ttl u

Q) -o..... V')

-o Q) ::::! .....s::: of-) s::: 0 u

r-... ex::I .....X -o s::: Q) c.. c.. ex:: 145

..... >< )> I -.....! n 0 :::s rt..... :::s c 11) 0.

.....(I')

c... c :::s 11) 146

,..... Q) s:: .,s:: ..s:::: u Q) "'0.,.... V)

"'0 Q) :::s .,....s:: .f-) s:: 0 u ......

r--.. I c::x: .,....X "'0 s:: Q) c.. c.. c::x: 147

..... X )> I ""'-~ n 0 ::I rt..... ::I c m 0..

.....V'l 0.. m ("') ::r ::I ::I"' m......

0n 8" 0"' m -s 148

0 co en ..-!

QJ s:: ::::s "':)

r- QJ s:: s:: rtS ..c: u QJ "'0...... (/')

"'0 QJ ::::s ...... s:: .jJ s:: 0 u

,...._. I c:( ...... X "'0 s:: QJ c.. c.. c:( 149

...... >< )> I ......

(') 0 :::s rt...... :::s c: m 0.

...... (./') 0. m n :::r Ql :::s :::s m__,

...... \0 00 0 150

Appendix B. Aquatic macroinvertebrate taxa' collected with a 252-cm 2 . Ponar grab and artificial substrates during 1978, 1979, and 1980 from Pool 13, upper Mississippi River.

Taxon

Platyhelminthes Turbellaria Tricladida

Annelida Oligochaeta Hirudinea Rhynchobdellida Glossiphoniidae Helobdella sp. Placobdella sp.

Arthropoda Crustacea Isopoda Asell idae Asellus sp. Amphipoda Gammaridae Gammarus sp. Talitridae Hyallela azteca (Saussure) 151 Appendix B. (continued.)

Taxon

Arachnoidea Hydracarinaa Insecta Plecoptera Perlidae Perlesta placida (Hagen) Ephemeroptera Baetidae Baetis sp. Baetiscidae Baetisca sp; Caenidae Brachycercus sp. Caenis sp. Ephemeroidea Ephemeridae Hexagenia sp. H. bilineata (Say) H. limbata (Serville) Pentagenia sp. Polymitarcidae Ephoron sp. 152 Appendix B. (continued.)

Taxon

Heptageniidae Stenacron sp. Stenonema sp. Leptophlebiidae Paraleptophlebia sp. Odonata Gomphidae Arigomphus sp. Dromogomphus sp. Gomphus sp. Ophiogomphus sp. Styl urus sp. Libellul idae Pantala sp. Coenagrionidae Anomalagrion hastatum (Say) Argia sp. Enallagma sp. Ischnura sp. Hemiptera Corixidae Hebridae 153

Appendix B. (continued.)

Taxon

Pleidae Neoplea striola (Fieber) Trichoptera Hydropsychidae Cheumatopsyche sp. Hydropsyche sp. H. orris Ross Potamyia flava (Hagen) Hydroptilidae Leptoceridae Ceraclea sp. Nectopsyche sp. Oecetis sp. Philopotamidae Chimarra sp. Polycentropodidae Neureclipsis sp. Lepidoptera Pyralidae Acentropus sp. Coleoptera Elmidae Dubiraphia sp. Stenelmis sp. . 154

Appendix B. (continued.)

Taxon

Staphylinidae Diptera Ceratopogonidae Chironomidae Culicidae Chaoboridae Chaoborus sp. Empididae Muscidae · Psychodidae Pericoma sp. Sciomyzidae Stratiomyidae

Mollusca Gastropoda Mesogastropoda Hydrobiidae Amnicola sp. Basommatophora Lymnaeidae Lymnaea sp. 155

Appendix B. (continued.)

Taxon

Physidae Physa sp. Pelecypoda Heterodonta Corbiculidae Corbicula manilensis (Philippi) Sphaeriidae Pisidium sp. Sphaerium sp. Schizodonta Unionidae Fusconaia flava (Rafinesque) Leptodea fragilis (Rafinesque) Obliguaria reflexa Rafinesque Obovaria olivaria (Rafinesque) Truncilla sp.

T. donaciformes

a .. Hydracarina 11 is not a s.pecifi"c taxonomic term, but a term of convenience (Pennak 1978). It is an aggregation of families in the suborder Trombidiformes. 156

Appendix C. Fish species caught by electrofishing, hoop netting, and seining during 1978, 1979, and 1980 from Pool 13, upper Mississippi River.

Common name Scientific name

Shovelnose sturgeon Scaphirhynchus platorynchus Paddlefish Polyodon spathula Longnose gar Lepisosteus osseus Shortnose gar Lepisosteus platostomus Bowfin Amia calva Gizzard shad Dorosoma cepedianum Goldeye Hiodon alosoides

~1ooneye Hiodon tergisus Northern pike Esox lucius Carp Cyprinus carpio Silvery minnow Hybognathus nuchalis Speckled chub Hybopsis aestivalis Silver chub Hybopsis storeriana Emerald shiner Notropis atherinoides River shiner Notropis blennius Spottail shiner Notropis hudsonius Spotfin shiner Notropis spilopterus Fathead minnow Pimephales promelas Bullhead minnow Pimephales vigilax Blue sucker Cycleptus elongatus 157

Appendix C. (continued.)

Common name Scientific name

River carpsucker Caq~iodes carpio

Qui 11 back Caq~iodes c~prinus Highfin carpsucker Carpi odes velifer Smallmouth buffalo Ictiobus bubalus

Bigmouth buffalo Ictiobus c~prinellus Black buffalo Ictiobus niger

Spotted sucker Min~trema melanops Silver redhorse Moxostoma anisurum

Golden redhorse Moxostoma er~thrurum Shorthead redhorse Moxostoma macrolepidotum Black bullhead Ictalurus mel as Yellow bullhead Ictalurus natal is Channel catfish Ictalurus punctatus Stonecat Noturus flavus Tadpole madtom Noturus gyrinus Flathead catfish Pylodictis olivaris Trout-perch Percopsis omiscomaycus Brook silverside Labidesthes sicculus White bass Marone chrysops Yellow bass Marone mississippiensis Rock bass Ambloplites rupestris Pumpkinseed Lepomis gibbosus Orangespotted sunfish Lepomis huinilis 158

Appendix C. (continued.)

Common name Scientific name

Bluegill Lepomis macrochirus Smallmouth bass Micropterus dolomieui Largemouth bass Micropterus salmoides White crappie Pomoxis annularis Black crappie Pomoxis nigromaculatus Johnny darter Etheostoma nigrum Yellow perch Perea flavescens Log perch Percina caprodes River darter Percina shumardi Sauger Stizostedion canadense Walleye Stizostedion vitreum Freshwater drum Aplodinotus grunniens

I. ,

Appendix D. Subsample counts for large catches of Potamyia flava (Hagen) collected with a 252-cm2 Ponar grab, October 2 and 3, 1979, Pool 13, upper Mississippi River (refer to Figures 1 and 2 for locations). The counts were found to be random when tested for a Poisson distribution (Cummins 1975: section 8.23, Elliott 1977: section 8.3).

Water volume (ml) Counts of No. of Site Replicate Total Subsample organisms

26-2-8 2 6000 500 28, 38, 35, 21, 25 "'LO .-I 26-2-8 3 3000 500 32, 36, 21, 25, 42 26-3-8 1 2000 500 19, 19' 19, 27, 29 29-6-8 3 2000 600 15, 18, 19, 21, 21, 21

30-5-8 3 4000 500 20, 19, 23, 21, 11 Appendix E. Subsample counts for large catches of invertebrates collected with artificial substrates, October 6, 1979, Pool 13, upper Mississippi River (refer to Figure 1 for locations). The counts were found to be random when tested for. a Poisson distribution (Cummins 1975: section 8.23, Elliott 1977: section 8.3).

Wing Sample Orientationb Sampler Water volume (ml) Counts of No. of dam sitea to wing dam t~Qec Total SubsamQle organisms 25 6 7 B 5,000 300 10, 8, 18, 16, 17, 16

25 6 7 MP 5,000 500 16, 14' 17' 16, 20

26 6 7 B 10,000 500 22, 23, 26, 36, 31 ...... C) 0 26 6 7 ~1P 4,000 1,000 32, 22, 15, 27, 27

26 6 8 B &MPd 4,000 600 20, 16' 15, 16, 25, 28 29 5 7 B 5,000 500 20, 27, 33, 31, 31

29 5 7 MP 5,000 800 12' 11' 9, 19, 13' 12' 10' 10 29 5 8 B 10,000 250 36, 22, 20, 26, 18 29 5 8 MP 5,000 500 37, 27, 22, 19, 26 30 5 7 B 15,000 250 27, 27, 29, 27, 23 30 5 7 MP 5,000 500 21, 24, 18, 34, 20 30 5 8 B 15,000 250 26, 13, 30, 25, 23 30 5 8 MP 5,000 500 26, 37, 28, 30, 35 Appendix E. (continued.) aSample site: 5 = inside transect, 6 = outside transect. bOrientation on wing dam: 7 = upstream, 8 = downstream. cSampler type: B = basket sampler, MP = multiple-plate sampler. dsamples from basket and multiple plate samplers were inadvertently combined during sorting. Appendix F. Benthic invertebrate density (No.) per m2 collected with a 252-cm2 Ponar grab from the side channel and wing dams in each sampling period before and after notching, Pool 13, upper Mississippi River. Ninety-five percent confidence intervals (95% CI), chi-square variance to mean ratio, k from the negative binomial distribution, precision (D), and number of sampling units required forD= 20% were calculated from the formulae of Elliott (1977). Notching took place in May-July 1979. Benthic invertebrate samples were not collected at wing dam 26 in June 1979 because the dam was being notched at the time of sampling. Three replicate samples taken at benthos site 25-2-8 in August 1979 were lost (refer to Figures 1 and 2 for locations). Appendix F. (continued.)

No. of sampling units Date n Median Mean 95% CI chi-square k D(%)b required for D = 2~

BEFORE NOTCHING June 1978 81 357 903 ( 567- 204687a 0.34 19.0 71 1239) August 1978 81 119 476 ( 272- 142562a 0.25 22.0 94 680) September 1978 81 278 2928 ( 915- 2263561a 0.10 35.1 250 4941) September 1978 c 75 198 757 { 525- 99719a 0.55 15.6 45 989) June------~--~~--- 1979 69 436 663 ( 489- 53465a 0.83 13.2 30 (V) 1.0 837) ..-1 AFTER NOTCHING No. of sampling units Date n Median Mean 95% CI chi-square k D(%)b required for D = 20%

August 1979 78 1290 2189 (1646- 204205a 0.83 12.4 30 2732) October 1979 81 2540 5565 (3185- 166560~ 0.27 21.4 93 c 7945) October 1979 69 1786 2770 (1985- 261166a 0.72 14.2 35 3555) June 1980 81 526 944 ( 697- 104754a 0.72 13.1 35 1191) July 1980 81 2341 2599 (2165- 118369a 1. 76 8.4 14 3033)

ap_<0.01, i.e. reject hypothesis of agreement with a Poisson series; it should be concluded that benth-ic organisms were contagiously, not randomly distributed on the river bottom. Appendix F. (continued.) bo =standard error x 100/arithmetic mean. Several authors have considered 0 = 20% to be a tolerable

error for benthic samp 1es (Cummins 1975, Elliott 1977, Resh 1979, Downing 1979, Ha 11 1980). cWith data from benthos sites 31-5-7 and 31-5-8 in September 1978, and 26-2-8, 26-3-8, 26-4-8 and

30-5-8 in October 1979 eliminated because of atypically high Trichoptera and Chironomidae densities

and gravel content. ------

Appendix G. Comparison of current velocities before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River. The relationship (regression} of current velocity (m/s) to staff gauge level (m) after notching was used to predict current velatity at prenotching staff gauge levels. Predicted and observed prenotching velocity values were then compared with a paired t-test. When the regression of postnotching current velocity and staff gauge level was not significant, the predictive regression was calculated from prenotching data, and the paired t-test used to compare predicted and ., observed postnotching values. For notched dams, benthos sites 2-8, 3-8, and 4-8, and ! hydrographic relief site 1-5 were included in the analysis. For unnotched dams and the side channel, all benthos and hydrographic relief sites were included, except benthos site 11 and hydrographic relief site 11-9 in the side channel (refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September-October 1978. Postnotching months were August, October 1979, and June, July-August 1980. Appendix G. (continued.)

BOTTOM VELOCITY Predictive regression t-test

•.,O.• ·---·M--• Site Regression equation r d. f. td d. f.

Side channela ln (Y + 0.005) = -3.169 + 2.121 ln X 0.581g 50 0.05 25 Wing dam 25a ln Y = -3.087 + 1.880 ln X 0.896g 14 2.06 7 Wing dam 26b ln Y = -4.864 + 3.451 ln X 0. 903 g 10 -8.85c 11 Wing dam 28a ln (Y + 0.005) = -4.933 + 4.360 ln X 0. 646g 14 2.62d 7 ...... Wing dam 29a + + 0. 538g -6.31e 0'1 ln (Y 0.005) = -3.009 1.858 ln X 38 19 0'1 Wing dam 30a ln Y = -2.550 + 1.897 ln X 0.817 g 38 -0.37 19 Wing dam 31a ln Y = -2.415 + 1.795 ln X 0. 769 g 38 0.87 19

MEAN VELOCITYf

Side channela ln Y = -2.658 + 1.723 ln X 0.6139 50 -0.24 25

Wing dam 25a ln Y = -2.618 + 1.662 ln X 0.892 g 14 1. 94 7

Wing dam 26a ln Y = -1.436 + 0.746 ln ~ 0.808 g 14 7.64c 7 Wing dam 28a ln (Y + 0.005) = -3.855 + 3.369 ln X 0.640 g 14 2.75d 7 Appendix G. (continued.)

Predictive regression t-test Site Regression equation r d. f. td d. f.

Wing dam 29b ln Y = -1.884 + 1.278 ln X 0. 592 g 28 1.54 29 Wing dam 30a ln Y = -2.058 + 1.726 ln X 0.824 g 38 -0.65 19 Wing dam 31a ln Y = -1.696 + 1.370 ln X 0.876 g 38 1.35 19

,...._ SURFACE VELOCITY \.0 ...-I g Side channela ln (Y + 0.005) = -2.447 + 1.561 ln X 0.528 50 -0.89 25 Wing dam 25a ln Y = -2.319 + 1.435 ln X 0.872 g 14 . 0.52 7 Wing dam 26a ln Y = -1.418 + 0.950 ln X 0. 927 g 14 3.03d 7 Wing dam 28b 1n Y = -2.853 + 2.245 ln X 0. 966 g 10 -0.12 11 e Wing dam 29a ln Y = -1.973 + 1.109 ln X 0.460 g 38 -5.34 19 Wing dam 30a ln Y = -1.746 + 1.448 ln X 0. 758 g 38 -2.94e 19 Wing dam 31a ln Y = -1.375 + 1.130 ln X 0. 821 g 38 0.45 19

aPredictive regression equation calculated from postnotching data. June 1978 data were not included in the analysis because of extremely high river stage. Appendix G. (continued.) bPredictive regression equation calculated from prenotching data. July-August 1980 data were not included in the analysis because of extremely low river stage. cSignificant increase in velocity after notching (£. <0.01). dSignificant increase in velocity after notching(£.~ 0.05). eSignificant decrease in velocity after notching (Q < 0.01). fMean velocity = velocity at 0.2 of the depth + velocity at 0.8 of the depth divided by 2 (two-point method). When one or both of the velocity readings needed for the two-point method had not been obtained, mean velocity was determined as the current velocity at 0.6 of the depth (USDI Bureau of Reclamation 1971). g £. 5 0.01. 169

Appendix H. Comparisons (t-tests) of percent silt-clay, percent sand, and percent gravel in the substrate in the side channel and at each wing dam before and after notching, Pool 13, upper Mississippi River. The arcsines of the square roots of the percentages were averaged for each month and compared with two-sample t-tests (Zar 1974). At notched dams, data for benthos sites 2-8, 3-8, and 4-8, and hydrographic relief site 1-5 were included in the analyses. For unnotched dams, data were included for all benthos and hydrographic relief sites, except hydrographic relief sites 29-1-4, 30-1-4, and 31-1-5 which were eliminated due to missing samples. For the side channel, data were included for all benthos sites; substrate samples were not collected at hydrographic relief sites in the side channel (refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September-October 1978. Postnotching months were August, October 1979, and June, July-August 1980 .. Appendix H. (continued.)

Percent Silt-Clay Percent Sand Percent Gravel Site t d. f. t d. f. t d. f. Side channel 2. 91a 5 -3.00a 5 -0.31 5 Wing dam 25 1.12 5 -1.19 5 -0.52 5 Wing dam 26 0.32 5 -0.41 5 -1.92 5 Wing dam 28 -1.06 5 0.83 5 -0.41 5 ...... '-I Wing dam 29 -0.91 5 1.03 5 -0.31 5 0 Wing dam 30 -2.51 5 2.29 5 -0.82 5 Wing dam 31 -3.10a 5 0.18 5 1.35 5 a£.~0.05 171

Appendix I. Mann-Whitney tests of benthic invertebrate density (No.) and biomass (g) per m2 and number of taxa collected with a 252-cm 2 Ponar grab in the side channel and at each wing dam, before and after notching, Pool 13, upper Mississippi River. For notched dams, data for benthos sites 2-8, 3-8, and 4-8 were included in the analyses. For unnotched dams and the side channel, data were included for all benthos sites (refer to Figures 1 and 2 for locations). Prenotching months were June, August, and September 1978. Postnotching months were August, October 1979, and June 1980. July 1980 data were not included to balance seasonal differences as explained in the text. Appendix I. (continued.)

Density Biomass Taxa

Site d n1' n2 d n1' n2 u n1' n2

Side channel 1. 70 27, 27 0.45 27, 27 40.0 9a' 9 Wing dam 25 0.16 27, 24 -1.94 27, 24 47.0 9, 8a Wing dam 26 3.85b 27, 27 3.61b 27, 27 63.5c 9, 9a

Wing dam 28 4.05b 27, 27 3.02b 27, 27 67.0c 9, 9a ,_...... Wing dam 29 3. nb 36, 36 4.17b 36, 36 97.0 12, 12a N Wing dam 30 s.5ob 36, 36 5.25b 36, 36 122.5b 12' 12a Wing dam 31 3.43b 36, 36 3.10b 36, 36 lll.Ob 12, 12a alarger statistic of the pair (Zar 1974). bQ ::..::'0 • 01 •

CQ ':; 0. 05. Appendix J. Kruskal-Wallis tests and nonparametric multiple comparisons (Zar 1974} of benthic invertebrate density (No.) per m2 collected with a 252-cnl Ponar g,rab in each samp-ling; month, Pool 13, upper Mississippi River. For notched dams, data for benthos sites 2-8, 3-8, and 4-8 were included in the analysis. For unnotched dams and the side channel, data were included for all benthos sites (refer to Figures 1 and 2 for locations).

SIDE CHANNEL

H = 15. 721* d.£. = 7 Multiple Comparisons

_... .. ('I) Rank(i) VS q q I' Rank Sum(Ri) n. Date i ia VS ib q ia v.s ib ..-i 1. a ~

1 235.5 9 Aug. 1978 8 vs 1 4.36* 8 vs 4 5.76** 8 VS 7 5.56-**

2 264.0 9 Aug. 1979 8 vs 2 4.46* 8 vs 5 7.06** 7 vs 1 3.36

3 271.5 9 June 1978 8 VS 3 5.03** 8 vs 6 6.26** •

4 282.0 9 Sept. 1978

5 286.0 9 June 1979

6 360.0 9 June 1980

7 420.0 9 Oct. 1979

8 509.0 9 July 1980

*e. ~ 0.05 **e_sO.Ol Appendix J. (continued.)

WING DAM 25

H == 31.868** d.f. == 7 Multiple Comparisons

Rank(i) Rank Sum(R.) n. Date ia vs ib q ia VS ib q ia VS ib q ~ ~

1 163.5 9 June 1979 8 vs 1 5.99** 7 VS 1 4.84* 5 VS 1 5.24**

2 182.0 9 June 1980 8 VS 2 6.50** 7 VS 2 5.24** 5 vs 2 5.95**

3 214.0 9 June 1978 8 VS 3 6.90** 7 vs 3 5.47** 5 VS 3 6.55**

4 316.0 9 Aug. 1978 8 vs 4 5.67** 7 VS 4 3.59 4 vs 1 4.82** I-' -...... ! 5 370.0 9 Aug. 1979 8 VS 5 5.36** 6 vs 1 5. 30** 4 VS 2 5.63** +=-

6 413.5 9 Oct. 1979 8 VS 6 5.29** 6 VS 2 5.88** 4 VS 3 6.37**

7 429.5 9 Sept. 1978 8 vs 7 6.87** 6 VS 3 6.31** 3 VS 1 2.12

8 539.5 9 July 1980

*E. ~ 0.05 **E. ~c:_ 0. 01 Appendix J. (continued.)

WING DAM 26

H = 39.587** d.f. = 7 Multiple Comparisons

Rank(i) Rank Sum(R.) n. Date i VS ib q i vs ib q i vs ib q ~ ~ a a a

1 125.0 9 Sept. 1978 7 VS 1 7.33** 6 vs 2 5~66** 5 vs 3 5.7'3**

2 168.0 9 Aug. 1978 7 vs 2 7. 63** 6 vs 3 6.11** 5 vs 4' 3.,9'j·1Hi'

3 198.0 9 June 1980 7 vs 3 8.38** 6 VS 4 5.02** 4 'irs 1 4;.6'4**

LO 4 271.5 9 June 1978 7 VS 4 8.12** 6 VS 5 3.53* 4 vs 2 4.35** r--. ...-f 5 334.5 9 July 1980 7 vs 5 8.13** 5 vs 1 5.32** 4 VS 3 4~59**

6 391.0 9 Aug. 1979 7 VS 6 8.55** 5 vs 2 5.27** 3 VS 1 3.07

7 528.0 9 Oct. 1979 6 vs 1 5.64**

*E. s 0.05 **p :::: 0. 01 Appendix J. (continued.)

WING DAM 28

H = 35.962** d. f. = 7 Multiple Comparisons

Rank (i) Rank Sum(R.) n. Date ia VS ib q ia VS ib q i VS ib q l. l. a

1 114.0 9 Aug. 1978 8 VS 1 6.12** 7 VS 2 7.19** 5 VS 1 6.65**

2 147.0 9 Sept. 1978 8 vs 2 6.38** 7 VS 3 4.84** 5 VS 2 7.25**

3 296.0 9 June 1978 8 VS 3 4.28* 7 VS 4 5.63** 4 VS 1 6.15**

4 308.5 9 June 1980 8 vs 4 4.81** 7 VS 5 4.64** 4 VS 2 6.78** ...... ""'-~ 0"1 5 376.0 9 June 1979 8 VS 5 3.86* 7 VS 6 5.28** 3 vs 1 7.64**

6 402.0 9 Aug. 1979 8 vs 6 4.03* 6 VS 1 6.10** 3 vs 2 9.30**

7 486.5 9 Oct. 1979 8 VS 7 0.72 6 VS 2 6.47** 2 VS 1 2.06

8 498.0 9 July 1980 7 VS 1 6. 77** 6 vs 3 3.35

*E. 0.05 **E.-- 0.01 Appendix J. (continued.)

WING DAM 29

H = 34.178** d.f. = 7 Multiple Comparisons i vs q Rank(i) Rank Sum(R,) n. Date ia VS ib q ia vs ib q a ib ~ ~

1 284.0 12 Aug. 1978 8 vs 1 6.83** 7 VS 1 5.39** 5 vs 2 5.35**

2 331.5 12 Sept. 1978 8 vs 2 7.24** 7 VS 2 5.63** 4 VS 1 . 5.64**

3 534. 5-- 12 June 1979 8 VS 3 5.63** 7 VS 3 3.39 4 vs ~ 6.19*" f'o., -f'o., 4 557.5 12 June 1978 8 VS 4 6. 37** 6 VS l 5.39** 3 vs 1 6.86** 5 591.0 12 June 1980 8 VS 5 7.26** 6 vs 2 5.68* ... 3 vs 2 8.~9**

6 675.0 12 Aug. 1979 8 vs 6 7.34*"" 5 VS 1 5.07** 2 VS 1 1.94

7 739.5 12 Uct. 1979 8 VS 7 8.31**

8 943.0 12 July 1980

*E. 0.05 **E. ~·-· 0. 01 Appendix J. (continued.)

WING DAM 30

H = 61.627** d.f. 7 Multiple Comparisons

Rank(i) Rank Surn(R.) n. Date i vs q ia vs ib q ia vs q ]_ ]_ a ib ib

1 144.0 12 Aug. 1978 8 VS 1 8.80** 7 VS 3 7.12** 5 vs 1 7.07**

2 375.0 12 Sept. 1978 8 VS 2 7.32** 7 VS 4 8.62** 5 VS 2 4.05*

3 441.5 12 June 1979 8 vs 3 7.61** 7 vs 5 8.23** 5 vs 3 3. 56* ...... 4 454.0 12 June 1978 8 vs 4 8.92** 7 VS 6 2.76 5 VS 4 4.80** co-.....!

5 571.5 12 June 1980 8 vs 5 a. 70** 6 VS 1 9.11** 4 vs 1 6.39**

6 804.5 12 Aug. 1979 8 VS 6 5.18** 6 vs 2 7.10** 4 vs 2 2.16

7 872.0 12 Oct. 1979 8 vs 7 4.97** 6 VS 3 7.49** 3 VS 1 8.15**

8 993.5 12 July 1980 7 vs 1 8.62** 6 VS 4 9.60** 2 VS 1 9.43*"'

7 VS 2 6.86** 6 vs 5 9.51**

*.£ . - 0. 05 **.£ ' 0.01 Appendix J. (continued.)

WING DAM ~1

H = 14.067** d.f. = 7 Multiple Comparisons

Rank(i) Rank Sum(R Date i VS ib q i VS ib q ia vs i q i ni a a b

1 249.0 12 Aug. 1978 8 VS 1 6.49** 7 VS 4 7.55** 5 vs 3 4.37**

2 265.0 12 June 1978 8 VS 2 7.22** 7 VS 5 6.85** 5 VS 4 4.74**

3 463.5 12 June 1980 8 VS 3 5.68** 6 VS 1 7.61** 4 vs 1 5.32** 0) ...... ~ 4 507.0 12 June 1979 8 VS 4 6.08** 6 VS 2 8.85** 4 VS 2 .6.63**

5 623.0 12 July 1980 8 VS 5 5.20** 6 VS 3 6.95** 4 vs 3 1. 78

6 800.5 12 Sept. 1978 8 VS 6 2.04 6 VS 4 8.04** 3 VS 1 5.81:3**

7 873.0 12 Oct. 1979 7 VS 1 7 .39** 6 VS 5 7.25** 3 vs 2 8.11**

8 875.0 12 Aug. 1979 7 VS 2 8.39** 5 VS 1 6.18** 2 VS 1 0.65

7 VS 3 6.77** 5 VS 2 7.38**

*E.< 0.05 **E. •. 0.01 Appendix K. Kruskal-Wallis tests and nonparametric multiple comparisons (Zar 1974) of benthic invertebrate biomass (g) per m2 collected with a 252-cm2 Ponar grab in each sampling month, Pool 13, upper Mississippi River. For notched dams, data for benthos sites 2-8, 3-8, and 4-8 were included in the analysis. For unnotched dams and the side chanriel,. data were included for all benthos sites (refer to Figures 1 and 2 for locations).

SIDE CHANNEL

H = 5.905 d.f. = 7 Appendix K. (continued.)

WING DAM 25

H = 38.752** d.f. = 7 Multiple Comparisons

Rank (i) Rank Sum(R.) n. Date i vs ib q ia vs ib q ia vs ib q ~ ~ a

1 136.5 9 June 1979 8 VS 1 6.41** 7 VS 2 6.63** 6 vs 4 6.91**

2 182.0 9 Aug. 1978 8 VS 2 6.49** 7 vs 3 6.09** 6 vs 5 9.36**

.-i 3 255.0 9 Aug. 1979 8 vs 3 6.02** 7 VS 4 6.79** 5 VS 1 4.02* co .-i 4 280.5 9 June 1980 8 VS 4 6.56** 7 VS 5 8.40** 5 VS 2 3.58

5 295.0 9 July 1980 8 VS 5 7.72** 7 vs 6 3.12* 4 vs 1 4.56**

6 445.0 9 Oct. 1979 8 VS 6 3.95* 6 VS 1 6.54** 3 vs 1 4. 98**

7 495.0 9 June 1978 8 vs 7 2.75 6 vs 2 6.68** 2 vs 1 2.84*

8 539.0 9 Sept. 1978 7 vs 1 6.52** 6 VS 3 6.01**

*E...::::: 0. 05 **E..·:; 0.01 Appendix K. (continued.)

WING DAM 26

H = 30.150** d. f. = 6 Multiple Comparisons

Rank(i) Rank sum (R. > n. Date i VS ib q ia VS ib q i vs ib q l. l. a a

1 153.0 9 Aug. 1978 7 VS 1 6.53** 7 VS 5 9.37** 6 VS 3 4.82**

2 185.0 9 Sept. 1978 7 VS 2 6.93** 7 VS 6 8 .40** 6 vs 4 4.33**

3 225.0 9 June 1980 7 VS 3 7.28** 6 vs 1 4.76** 6 vs 5 5.52** ..... (X) 4 274.5 9 June 1978 7 VS 4 7.51** 6 VS 2 4.89** 5 vs 1 3.45 N

5 289.0 9 July 1980

6 377.5 9 Aug. 1979

7 512.0 9 Oct. 1979

*p . 0.05 **p :, 0.01 Appendix K. (continued.)

WING DAM 28

H = 25.898** d. f. = 7 Multiple Comparisons

Rank (i) Rank Sum(R n Date i VS ib q ia VS ib q ia vs ib q i i a

1 158.5 9 Aug. 1978 8 vs 1 5.96** 7 vs 1 4. 77* 5 VS 2 4.13*

2 200.0 9 Sept. 1978 8 vs 2 6.06** 7 vs 2 4.67* 4 vs 1 4.90**

(V') 3 281.0 9 June 1979 8 VS 3 5.34** 7 vs 3 3.54 4 VS 2 4. 77** ...... co 4 313.5 9 June 1980 8 vs 4 5.57** 6 VS 1 4.93** 3 VS 1 5.15**

5 330.5 9 June 1978 8 vs 5 6.41** 6 vs 2 4.85** 3 VS 2 5.06**

6 391.0 9 Aug. 1979 8 VS 6 5.96** 5 vs 1 4.37* 2 vs 1 2.59

7 420.5 9 Oct. 1979 8 VS 7 7.02**

8 533 .o 9 July 1980

*p ::::.. 0.05 **p ~::: 0. 01 Appendix K. (continued.)

WING DAM 29

H = 29.379** d.f. = 7 Multiple Comparisons

Rank(i) Rank Sum (R.) n Dat~ i VS i q i VS i q ia VS ib q 1 i a b a b

1 246.0 12 Aug. 1978 8 vs 1 6.38** 7 vs 1 5.68** 5 VS 2 5.55**

2 367.0 12 Sept. 1978 8 VS 2 5.86** 7 vs 2 4.95** 4 vs 1 7.12**

3 542.0 12 June 1978 8 vs 3 4.41* 7 vs 3 3.04 4 vs 2 6.15**

!-" 12 June 1979 8 VS 4 4.47* 6 VS 1 6.06** 3 VS 1 8.11** (X) 4 591.5 +=> 5 636.0 12 Aug. 1979 8 vs 5 4.66** 6 VS 2 5 • .26** 3 VS 2 7.15**

6 685.5 12 June 1980 8 vs 6 4.84** 5 VS 1 6.45** 2 VS 1 4.94**

7 726.0 12 Oct. 1979 8 VS 7 5.55**

8 862.0 12 July 1980

*p 0.05 **p 0.01 Appendix K. (continued.)

WING DAM 30

H = 48.432** d.f. 7 Multiple Comparisons

Rank (i) Rank Sum (R.) n Date i VS q i VS ib q i vs i q 1. i a ib a a b

1 192.0 12 Aug. 1978 8 VS 1 7.00** 7 VS 4 6.50** 5 VS 4 8.82**

2 289.5 12 Sept. 1978 8 vs 2 6.84** 6 VS 1 7.59** 4 vs 1 6.80**

3 467.5 12 June 1979 8 vs 3 5.52** 6 VS 2 7.49** 4 VS 2 6.37**

LO 4 522.0 12 June 1978 8 VS 4 5.71** 6 VS 3 5.67** 4 VS 3 2.23 co ..-i 5 738.0 12 Aug. 1979 8 VS 5 2.67 6 VS 4 6.04** 3 VS 1 7.55**

6 742.5 12 June 1980 7 VS 1 7.63** 5 VS 1 9.03** 3 vs 2 7.27**

7 837.0 12 Oct. 1979 7 vs 2 7.55** 5 VS 2 9.25** 2 VS 1 3.98**

8 867.5 12 Aug. 1980 7 VS 3 ' 6.11** 5 VS 3 7.41**

*E :-· 0.05 **E ~< o. 01 Appendix K. (continued.)

WING DAM 31

H = 35.649** d.f. = 7 Multiple comparisons

Rank(i) Rank Sum(Ri) n. Date ia VS ib q i vs i q i VS ib q ~ a b a

1 210.5 12 Aug. 1978 8 vs 1 6.92** 7 vs 4 4.43** 5 VS 3 3.43*

2 404.5 12 June 1978 8 VS 2 5.60** 7 vs 5 4.23** 5 vs 4 2.47

3 484.0 12 June 1979 8 vs 3 5.43** 6 vs 1 7.55** 4 VS 1 6.97** ...... CX) 4 548.5 12 July 1980 8 vs 4 5.45** 6 VS 2 5.84** 4 vs 2 3.95* 0\

5 609.0 12 June 1980 8 vs 5 5.55** 6 VS 3 5.65** 4 vs 3 2.63

6 758.0 12 Oct. 1979 8 vs 6 3.29 6 VS 4 5.74** 3 vs 1 7.49**

7 763.5 12 Sept. 1978 7 VS 1 6.54** 6 VS 5 6.08** 3 vs 2 3.25*

8 878.0 12 Aug. 1979 7 VS 2 4.95** 5 vs 1 6.59** 2 vs 1 7.92**

7 vs 3 4.62** 5 VS 2 4.22*

* p 0.05 ** p:-0.01 187

Appendix L. Comparison of electrofishing total catch per unit effort before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). The relationship (regression) of catch per unit effort (No./30 min) to staff gauge level (m) after notching was used to predict catch per unit effort at prenotching staff gauge levels. Predicted and observed prenotching catch per unit effort were then compared with a Wilcoxon paired-sample test (Conover 1971). When the regression of postnotching catch per unit effort on staff gauge level was not significant, the predictive regression was calculated from prenotching data, and the Wilcoxon test used to compare predicted and observed postnotching' values. Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. Append~x L. (continued.)

Predictive regression Wilcoxon test Site Regression equation r d. f. T n

Side channel CE & CW combinedc ln Y = 5.781 - 2.869 ln X -0.675a 10 44.0 12

Wing dam 25d 25-1S ln Y = 5.397 - 2.491 ln X -0.874a 4 2l.Of 6 ...... CXl 25-A & 25-B combined ln (Y + 0.5) = 4.446 - 4.836 ln X -0.965b 10 36.0g 8 CXl

d Emergent wing dams

26-1S & 28-1S combined ln Y = 5.285 - 2.257 1n X -0.810b 10 25.0 11 26-A & 28-A combined ln (Y + 0.5) = 5.302 - 5.097 1n X -0.961b 10 44.0 10 26-B & 28-B combined ln (Y + 0.5) = 5.030 - 4.282 1n X -0.908b 10 63.0 12 26-C & 28-C combined ln (Y + 0.5) = 3.415 - 3.817 ln X -0.821b 9 38.5 9

Unnotched wing dams d 29-1S, 30-1S, & 31-1S combinede ln Y = 4.429 - 1.601 ln X -0.669b 16 45.5 18 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined ln (Y + 0.5) = 1.218 - 1.936 ln X -0.560b 52 225.0 30 Appendix L. (continued.)

af ~ 0.05.

bQ:::; 0.01. cPredictive regression equation calculated from prenotching data. Not included in the analysis were 722 emerald shiners caught at transect CW in August 1978. dPredictive regression equations calculated from postnotching data.

~ eNot included in the analysis were 300 emerald shiners caught at transect 31-1S in August 1978, and 154 .-i river shiners at 31-1S in August 1980. fSignificant increase in catch per unit effort after notching (Q <:0.05).

gSignificant increase in catch per unit effort after notching (Q ~0.01). 190

Appendix M. Comparison of electrofishing catch per unit effort for freshwater drum, sauger, and carp before and after notching, after adjustment for changing river stage, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). The relationship (regression) of catch per unit effort (No./30 min) to staff gauge level (m) after notching was used to predict catch per unit effort at prenotching staff gauge levels. Predicted and observed prenotching catch per unit effort were then compared with a Wilcoxon paired-sample test (Conover 1971). When the postnotching regression of catch per unit effort on staff gauge level was not significant, or when the number of pairs of matched unequal values in the Wilcoxon test was less than 6 (Conover 1971), prenotching and postnotching electrofishing catches of selected species were compared with Mann-Whitney tests (Apps. Nand Q). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. / Appendix M. (continued.)

Freshwater Drum Predictive regression Wilcoxon test Sites Regression equation r d. f. T n

Side channel

CE & CW combined ln Y = 3.325 - 1.485 ln X -0.652a 10 l.Oc 11

Wing dam 25 o.od r-i 25-1S ln Y = 4.115- 2.075 ln X -0.902a 4 6 O'l r-i 25-A & 25-B combined ln (Y + 0.5) = 1.891 - 2.458 ln X -0.825b 10 o.oc 8

Emergent wing dams

26-1S & 28-1S combined ln Y = 3.657 - 1.929 ln X -0.769b 10 13.5d 12

26-A & 28-A combined ln (Y + 0.5) = 3.705- 3.834 ln X -0.911 b 10 19.0 10

26-B & 28-B combined ln (Y + 0.5) = 3.129- 3.190 ln X -0.860b 10 28.0 10

Unnotched wing dams

29-1S, 30-1S, & 31-15 combined ln Y = 3.806 - 2.470 ln X -0.741b 16 7.5c 18 Appendix M. (continued.)

Carp Predictive regression Wilcoxon test Site Regression equation r d. f. T n

Emergent wing dams 26-15 &28-15 combined ln (Y + 0.5) = 2.811 - 3.284 ln X -0.910b 10 37.5 10 26-A & 28-A combined ln (Y + 0.5) = 1.555 - 1.991 ln X -0.724b 10 13.0 8 26-B & 28-B combined ln (Y + 0.5) = 1.343 - 1.632 ln X -0.621a 10 27.0 8 ...... 1.0 N

Sauger

Emergent wing dams 26-15 & 28-15 combined ln (Y + 0.5) = 2.141 - 1.552 ln X -0.702a 10 43.0 11· 26-B & 28-B combined ln (Y + 0.5) = 1.005 - 1.374 ln X -0.639a 10 20.5 7

Unnotched wing dams 29-15, 30-15, & 31-15 combined ln (Y + 0.5) = 2.163 - 1.889 ln X -0.648b 16 65.5 14 Appendix M. (continued.) a Q ~ 0.05. b£. ~.:: 0.01. cSignificant increase in catch per unit effort after notching (£. ~ 0.01). dSignificant increase in catch per unit effort after notching (£. ~ 0.05). Appendix N. Median and mean catch per unit effort (No./30 min) of selected species in electrofishing catches before and after notching, Pool 13, upper Mississippi River (refer to Figures 1, and 3 to 6 for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. The only significant difference (Mann-Whitney tests) found for the species and locations listed in this table was an increase in catches of carp after notching at outside transects at wing dam 25 (25-A & 25-B combined) (App. Q).

Freshwater Drum · Before notching After notching , Site n Median Mean so n Median Mean so

Emergent wing dams

26-C ~ 28-C combined 12 1.00 2.42 4.54 11 0.00 3.27 7.04

Unnotched wing dams 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined 54 0.00 0.04 0.27 54 0.00 0.22 0.66 Appendix N. (continued.)

Sauger Before notching After notching Site n Median Mean SD n Median Mean SD

Side channe 1 CE & CW combined 12 2.00 3.67 3.85 12 5.00 5.17 4.32

Wing dam 25 1.0 Q)....,.. 25-1S 6 2.00 2.33 1.03 6 4.00 3.83 2.64

Emergent wing dams 26-A & 28-A combined 12 0.00 1.33 1. 97 12 0. 56 0.58 0.67 26-C & 28-C combined 12 0.00 0.75 1.36 11 0.00 0.09 0.30 Appendix N. (continued.)

Carp Before notching After notching Site n Median Mean so n Median Mean so

Side channel CE & CW combined 12 3.50 6.75 6.93 12 4.00 5.17 6.01

Wing dam 25 ...... 1..0 25-1S 6 2.00 2.00 1. 90 6 1.00 0.67 0.52 0'1 25-A & 25-B combined 12 0.00 0.00 0.00 12 0.50 3.67 7.46

Emergent wing dams 26-C & 28-C combined 12 0.00 2.33 3.89 11 0.00 3.46 10.80

Unnotched wing dams 29-1S, 30-1S, & 31-1S combined 18 0.00 0.72 1.18 18 0.50 0.78 0.94 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined 54 0.00 0.00 0.00 54 0.00 0.15 0.56 Appendix N. (continued.)

Bl uegi 11 Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel CE & CW combined 12 5.00 9.17 11.76 12 2.00 4.00 6.03

!'-.. Wing dam 25 0"1 .-I 25-1S 6 0.00 2.83- 4.40 6 1.00 2.17 2.64 25-A & 25-B combined 12 0.00 0.00 0.00 12 0.00 0.67 1.23

Emergent wing dams 26-1S & 28-1S combined 12 1. 50 11.00 21.52 12 1.00 5.58 8.75 26-A & 28-A combined 12 0.00 4.83 9.73 12 0.00 1.92 3.06 26-B & 28-B combined 12 0.00 6.42 13.66 12 0.00 1.83 2.59 26-C & 28-C combined 12 0.00 2.17 5.37 11 0.00 0.00 0.00

Unnotched wing dams 29-1S, 30-1S, & 31-1S combined 18 0.00 2.17 4.67 18 0.00 1.33 3.33 Appendix N. (continued.)

Shorthead Redhorse Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel CE & CW combined 12 1. 50 3.00 4.51 12 1.00 3.42 5. 71

Wing dam 25 ...... 1.0 25-1S 6 0.00 0.33 0.52 6 0.00 1.00 1.67 00

Emergent wing dams 26-1S & 28-1S combined 1'2 0.00 0.67 0.99 12 .o. 50 0.83 0.94 26-A & 28-A combined 12 1.00 2.50 3.00 12 0.00 0.50 0.80 26-B & 28-B combined 12 1.00 1.42 2.23 12 0.00 1.08 2.11 26-C & 28-C combined 12 0.00 0.92 1. 78 11 0.00 0.27 0.65

Unnotched wing dams 29-lS, 30-1S, & 31-1S combined 18 1.00 1.56 1.65 18 1.00 1.61 2.09 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined 54 0.00 0.11 0.46 54 0.00 0.61 1.46 Appendix N. (continued.)

Quill back Before notching After notching Site n Median Mean SD n Median Mean SD

Wing dam 25 25-15 6 1.00 2.17 2.71 6 0.00 0.50 0.84

0'1 Emergent wing dams 0'1 ....-! 26-15 & 28-15 combined 12 0.50 1.67 2.50 12 0.00 0.67 0.99 26-A & 28-A combined 12 0.00 0.17 0.39 12 0.00 0.25 0.45 26-B & 28-B combined 12 0.00 0.58 1.00 12 0.00 0.08 0.29 26-C & 28-C combined 12 o.oo 0.00 0.00 11 0.00 0.18 0.41

Unnotched wing dams 29-15, 30-15, & 31-15 combined 18 1.00 1.28 1.36 18 1.00 0.83 1.20 200

Appendix 0. Median and mean total catch per unit effort (No./24 h) in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River. Emergent wing dams were dams 26 and 28. Unnotched wing dams were dams 29, 30, and 31 (refer to Figures 1, and 3 to 6 for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. · -- --~------

Appendix 0. (continued.)

UNBAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 1.8 2.1 1.9 11 1.4 1.4 0,9 Wing dam 25 12 1.8 2.0 1.6 12 1.4 1.7 1.3 Emergent wing dams 0.9 1.1 0.9 .-I 23 0.9 1.7 2.1 24 0 N Unnotched wing dams 33 0.7 0.8 0.7 34 0.9 1.1 1.1

BAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channela 12 5.1 9.8 12.2 12 1.6 1.9 2.1 Wing dam 25 12 2.0 3.4 3.4 12 1.9 3.8 4.5 Emergent wing dams 24 2.0 3.3 3.3 23 1.0 1.8 2.2 Unnotched wing dams 36 2.0 3.0 3.2 36 1.1 1.9 2.1

aSignificant decrease in catch per unit effort after notching (App. R). 202

Appendix P. Median and mean catch per unit effort (No./24 h) of

selected spectes in u~baited and baited hoop nets before and after notching, Pool 13, upper Mississippi River. Emergent wing dams were dams 26 and 28. Unnotched wing dams were dams 29, 30, and 31 (refer to Figures 1, and 3 to 6 for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text. Appendix P. (continued.)

Carp UN BAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 0.00 0.00 0.00 11 0.00 0.03 0.09 Wing dam 25 12 0.00 0.00 0.00 . 12 0.00 0.00 0.00 Emergent wing dams 23 0.00 0.00 0.00 24 0.00 0.02 0.10 (V) 0 N Unnotched wing dams 33 0.00 0.00 0.00 34 0.00 0.01 0.05

BAITED Before notching After notching Site n Median Mean SD n Median r~ean so

Side channel 12 0.00 0.03 0.09 12 0.00 0.03 0.09 Wing dam 25 12 0.00 0.08 0.20 12 0.00 0.16 0.26 Emergent wing dams 24 0.00 0.13 0.34 23 0.00 0.11 0.23 Unnotched wing dams 36 0.00 0.19 0.51 36 0.00 0.01 0.05 Appendix P. (continued.)

Smallmouth Buffalo UNBAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 0.00 0.08 0.20 11 0.00 0.00 0.00 Wing dam 25 12 0.00 0.07 0.16 12 . 0.00 0.11 0.20

Emergent wing dams 23 0.00 0.03 0.11 24 0.00 0.03 0.12 N 0 ..,:::. Unnotched wing dams 33 0.00 0.06 0.22 34 0.00 0.06 0.16

BAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 0.00 0.48 0.80 12 0.50 0. 72 0.76 Wing dam 25 12 0.00 Lll 1.71 12 0.75 2.70 3.55 Emergent wing dams 24 0.75 1.63 2.64 23 0.00 0.99 1.81 Unnotched wing dams 36 0.50 1.06 1.69 36 0.50 1.29 1.87 Appendix P. (continued.)

Freshwater Drum UNBAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 0.00 0.12 0.30 11 0.30 0.43 0.50 Wing dam 25 12 0.50 0.67 0.59 12 0.40 0.64 0.82 Emergent wing dams 23 0.00 0.30 0.50 24 0.15 0.37 0.59

LO 0 Unnotched wing dams 33 0.00 0.14 0.31 34 0.00 0.22 0.43 N

BAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel .12 0.00 0.14 0.26 12 0.00 0.14 0.35 Wing dam 25 12 0.00 0.51 1.18 12 0.00 0.18 0.31 Emergent wing dams 24 0.00 0.16 0.37 23 0.00 0.23 0.52 Unnotched wing dams 36 0.00 0.06 0.20 36 0.00 0.10 0.25 Appendix P. (continued.)

Channel Catfish UNBAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channel 12 0.25 0.48 0.57 11 0.00 0.24 0.54 Wing dam 25 12 0.00 0.26 0.61 12 0.00 0.03 0.09

Emergent wing dams 23 0.00 0.09 0.19 24 0.00 0.14 0.27 N 0 a ()) Unnotched wing dams 33 0.00 0.03 0.12 34 0.00 0.34 0.88

BAITED Before notching After notching Site n Median Mean SD n Median Mean SD

Side channelb 12 3.25 8.03 11.89 12 0.15 0.84 1. 75 Wing dam 25 12 0.50 0.98 1.14 12 0.00 0.40 0.59 Emergent wing dams 24 0.50 0.65 0.76 23 0.00 0.23 0.43 Unnotched wing dams 36 0.50 1.34 2.70 36 0.10 0.37 0.61 ------

Appendix P. (continued.)

Flathead· Catfish UNBAITED Before notching After notching Site n Median Mean so n t4edi an Mean so

Side channel 12 0.00 0.08 0.20 11 0.00 0.37 0.49 Wing dam 25a 12 0.00 0.13 0.21 12 0.65 0.59 0.51 Emergent wing dams 23 0.00 0.10 0.25 24 0.00 0.18 0.25

0 "N Unnotched wing dams 33 0.00 0.24. 0.39 34 0.40 0.41 0.50

BAITED Before notching After notching Site n Median Mean so n Median Mean so

Side channel 12 0.00 0.04 0.14 12 0.00 0.00 0.00 Wing dam 25 12 0.00 0.08 0.20 12 0.00 0.19 0.39 Emergent wing dams 24 0.00 0.04 0.14 23 0.00 0.14 0.20 Unnotched wing dams 36 0.00 0.14 0.23 36 0.00 0.09 0.19

aSignificant increase in catch per unit effort after notching (App. S). bsignificant decrease in catch per unit effort after notching (App. S). 208

Appendix Q. Mann-Whitney tests of catch per unit effort (No./30 min) for selected species in electrofishing catches before and after notching, Pool 13, upper Mississippi River {refer to Figures 1, and 3 to 6 for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text.

Freshwater Drum

Site u n1' "2

Emergent wing dams 26-C & 28-C combined 66.5 12 , 11 a

Unnotched wing dams d 29-A, B, & C; 30...:A, B, & C; and 31-A, B, & C combined 1.15 54 ' 54

210

Appendix Q. (continued.)

Bl uegi 11

Site u n1, n2

Side channel CE & CW combined 49.5 12a, 12

Wing dam 25

25-1S 20.0 . 6 ' 6a 25-A & 25-B combined 96.0 12 12a

Emergent wing dams · 26-1S & 28-1S combined 63.0 12a, 12

26-A & 28-A combined 72.0 12 ' 12 26-B & 28-B combined 72.5 12 , 12a 26-C & 28-C combined 49.5 12a, 11

Unnotched wing dams 29-lS, 30-lS, & 31-lS combined 153.0 18a, 18 211

Appendix Q. (continued.)

Shorthead Redhorse

Site u nl' n2

Side channel CE & CW combined 71.0 12a, 12

Wing dam 25 25-1S 20.0 6 • 6a

Emergent wing dams 26-1S & 28-1S combined 80.0 12 • 12a 26-A & 28-A combined 41.0 12a, 12 26-B & 28-B combined 54.5 12a, 12 26-C & 28-C combined 48.5 12a, 11

Unnotched wing dams 29-1S, 30-1S, & 31-1S combined 155.0 18a, 18 d 29-A, B, & C; 30-A, B, & C; and 31-A, B, & C combined 1. 21 54 ' 54 212

Appendix Q. (continued.)

Qui 11 back

Site u

·Wing dam 25 25-1S 12.5

Emergent wing dams 26-1S & 28-1S combined 59.0 12a, 12 26-A & 28-A combined 78.0 12 ' 12 a 26-B & 28-B combined 53.0 12 ' 12 26-C & 28-C combined 78.0 12 ' lla

Unnotched wing dams 29-IS, 30-1S, & 31-1S combined 127.0 alarger statistic of the pair (Zar 1974). bSignificant increase in catch per unit effort after notching

(.Q. ~ 0. 05) . Appendix R. Mann-Whitney tests of total catch per unit effort (No./24 h) in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River. Emergent wing dams were dams 26 and 28. Unnotched wing dams were dams 29, 30, and 31 (refer to Figures 1, and 3 to & for locations). Prenotching months were June, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text.

Unbaited Baited Site (V") u nl' n2 u n1' n2 .--1 N Side channel 57.0 12a, 11 3l.Ob 12a, 12 Wing dam 25 66.5 12a, 12 70.0 12a, 12 d n1, nz d nl' n2

Emergent wing dams -0.22 23 ' 24 -1.62 24 ' 23 Unnotched wing dams 0.92 33 ' 34 -1.85 36 , 36

alarger statistic of the pair (Zar 1974}. bSignificant decrease in catch per unit effort after notching (2_ < 0.05). Appendix S. Mann-Whitney tests of catch per unit effort (No./24 h) for selected species in unbaited and baited hoop nets before and after notching, Pool 13, upper Mississippi River. Emergent wing dams were dams 26 and 28. Unnotched wing dams were dams 29, 30, and 31 (refer to Figures 1, and 3 to 6 for locations). Prenotching months were June·, August, and October 1978. Postnotching months were August, October 1979, and June, August 1980. Data for August 1979 and August 1980 were pooled to balance seasonal differences as explained in the text.

Carp Unbaited Baited Site u nl' n2 u n1, n2 ...... N +:=> Side channel 72.0 12 ' lla 72.0 12 , 12 Wing dam 25 72.0 12 , 12 83.0 12 , 12a

d n1, n2 d nl' n2

Emergent wing dams 0.24 23 ' 24 0.24 24 , 23 Unnotched wing dams 0.21 33 ' 34 -1.46 36 ' 36 Appendix S. (continued.)

Smallmouth Buffalo Unbaited Baited Site u n1, n2 u nl' n2 a Side channel 55.0 12a, 11 88.5 12 ' 12 Wing dam 25 78.5 12 ' 12a 93.0 12 , 12a

d n1, n2 d n1, n2

LO ...... Emergent wing dams -0.01 23 ' 24 -1.00 24 ' 23 N Unnotched wing dams 0.34 33 ' 34 0.38 36 ' 36

Freshwater Drum Unbaited Baited Site u n1, n2 u n1, n2

lla Side channel 96.5 12 ' 68.0 12a, 12 "' Wing dam 25 61.0 12a, 12 67.5 12a, 12

d n1, n2 d n1, n2

Emergent wing dams 0.48 23 ' 24 0.45 24 ' 23 Unnotched wing dams 0.79 33 ' 34 0.59 36 ' 36 Appendix S. (continued.)

Channel Catfish Unbaited Baited Site u n1' n2 u nl' n2

Side channel 48.5 12a, 11 29.0c 12a, 12 Wing dam 25 65.0 12a, 12 48.0 12a, 12 ...... N d n1, n2 d n1' n2 "'

Emergent wing dams 0.61 23 ' 24 -1.68 24 ' 23 Unnotched wing dams 2.02b 33 ' 34 -1.45 36 ' 36 Appendix S. (continued.)

Flathead Catfish Unbaited Baited Site u n1' n2 u n1' n2

Side channel 88.0 12 , lla 66.0 12a, 12 Wing dam 25 llO.Ob 12 12a 79.0 12 ' 12a

d nl' n2 d nl' n2

Emergent wing dams 1.11 23 ' 24 1.47 24 ' 23 Unnotched wing dams 1.34 33 ' 34 -0.57 36 ' 36

alarger statistic of the pair (Zar 1974). bSignificant increase in catch per unit effort after notching (Q ~ 0.05). cSignificant decrease in catch per unit effort after notching (Q~ 0.05). Appendix T. Lengths (mm) and weights (g) of selected species in electrofishing catches before and after notchinq. Pool 13. upper Mississippi River.

Length Weight Range Species n Mean Mi n.RangeMa x.. SD n Mean Min. Max. SD

Freshwater drum Before 447 167.3 52 398 54.9· 440 81.8 2 920 93.3 After 1538 121.2 6 429 55.'7 1527 37.7 1 1010 81.8

Sauger Before 211 219.2 101 447 .47.5 209 88.8 6 950 85.2 After 422 166.7 78 436 71.5 399 59.2 2 760 86.3 N ...... co Carp Before 237 456.1 218 744 70.7 236 1416.3 160 5380 626.7 After 342 452.7 . 151 702 60.1 343 1323.8 56 3225 493.6

Bluegill Before 459 107.5 27 203 36.4 396 44.5 1 236 36.8 After 948 92.6 18 209 43.0 666 41.8 1 238 42.3

Shorthead redhorse Before 135 262.3 98 492 91.0 134 269.4 9 1390 275.6 After 221 368.9 121 565 95.2 220 674.5 19 1535 389.1

Quill back Before 80 255.9 124 434 67.7 79 256.1 25 1125 181.2 After 62 318.7 114 446 75.9 62 482.4 20 1080 255.1 Appendix U. Lengths (mm) and weights (g) of selected species in hoop net catches before and after notching. Pool 13. upper Mississippi River.

Length Weight Range Range Species n Mean Min. Ma~. so n Mean Min. Max. so

Carp Before 23 349.0 203 602 89.1 23 677.2 142 2490 526.4 After 21 457.9 265 648 106.7 21 1208.6 277 3400 976.1

Smallmouth buffalo 0'1 ...-! Before 218 320.3 237 451 38.2 218 512.1 207 1325 191.8 C\J After 362 325.8 184 470 55.3 269 469.5 80 1270 240.6

Freshwater drum I I Before 70 234.5 124 388 50.1 70 180.0 4 900 135.3 After 106 202.4 98 346 47.1 105 110.0 20 530 86.7

Channel catfish Before 417 265.3 79 421 35.7 414 154.$ 10 720 68.2 After 144 254.5 92 419 60.3 142 140.9 6 670 107.6

Flathead catfish Before 46 317 •. 2 187 493 68.6 46 393.4 74 1620 296.9 After 115 301.8 104 539 . 70.9 99 273.3 13 1490 201.4 Appendix V through LL available on request from:

Federal Documents Section Learning Resources Center UW-Stevens Point Stevens Point, WI 54481 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II II I II II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I