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W: s .""‘ . - .,._ .. a . . «.- I, ~ 0 ca O. «.5. ; 1.‘5 " ‘7‘ .511, 1 l[' 1 'IK‘JVHW I .g , 1 r 1 :" ..-- 11. .1111'1‘fi1i.’ ;.-.I:‘:“ 1' “ 11-”}1,1“;11'.I1,J[LI1-. “:3 1' 1 4.: :11: 1'3111'1"'7113\f“' 1411‘“ $11 1‘Q1‘11'” 111.11 11:1 . i. G ' ' ~ N. o 1.111."1'*""1“ :‘11 '11‘.’ .11} 131.!- _1’§‘1f11‘111'f"¢“'1‘ .,1..‘7 V’P "“311191‘111 F.“ ’1’.” ‘p ”5121‘. {1' "g“ 111111135. 11,}. M1111? #1111111" 11111111111111.1111" 1,3,. LIBRARY A Michigan State University This is to certify that the thesis entitled POPULATION DYNAMICS OF, AND HABITAT UTILIZATION BY, YOUNG-OF-THE-YEAR ROCK BASS (Amblopiites rypestris) AND SMALLMOUTH BASS (Micrgpterus dolomieui) IN A WARM-WATER STREAM ~ presented by David C. Dowling has been accepted towards fulfillment of the requirements for Master of Science (mgnfighl Fisheries and Wildlife M,— {a $4 Major professor Date July 8, 1987 0-7639 MSUiJ an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES remove this your record RETURNING MATERIALS: Place in book drop to checkout from FINES will be charged if book is returned after the date stamped below. ! _-‘ f“ 2'". ‘6... (“1‘ A ——w iPRfilI “(9‘95 .3- 19-: r553 l;;. J '3 ‘7" $35.; 35-2" i3 JOEL-3'0 § 23301 2 6 2001 FEB 1 l '3 J . rs r- \ .I. ‘r' L Il ‘) J— 2‘} m . H 1" flmfi'. ," POPULATION DYNANICS OF, AND HABITAT UTILIZATION BY, YOUNG-OF-THE-YEAR ROCK BASS (Ambloglites rugestris) AND SMALLMOUTH BASS (Nicropterus dolomieui) IN A WARN-WATER STREAM By David C. Dowling A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1987 ABSTRACT POPULATION DYNAMICS OF, AND HABITAT UTILIZATION BY, YOUNG-OF-THE-YEAR ROCK BASS (Ambloplitgg rupestris) AND SMALLMOUTH BASS (Hicropterus dolomieui) IN A WARM-WATER STREAM BY David C. Dowling The Red Cedar River, a warmwater stream in the south central portion of Michigan, supports nine species of centrarchids in its drainage area with the rock bass and the smallmouth bass being two of the predominant species. This thesis reports the usage of vegetative cover, densities, growth rates, and sources of predation on the young-of-the-year (YOY) of these two species. Young-of-the-year rock bass and smallmouth bass primarily utilize the submergent macrophytes for cover. This was ascertained using a l m' throwtrap. Within this veQetation type there was always a small negative association between these two species. YOY rock bass densities do not appear to affect YOY smallmouth bass growth or vice-versa. Smallmouth bass growth was negatively correlated with its own density and positively correlated with temperature and dissolved oxygen. YOY rock bass growth seems to be unrelated to either abiotic parameters or cohort density. Rock bass were not found to be piscivorous but juvenile smallmouth bass and largemouth bass were found to have age Q rock bass in their stomachs. ACKNOWLEDGEMENTS I wish to express my sincere appreciation to my graduate committee, Dr. William Taylor, Dr. Darrell King, Dr. Niles Kevern, and Dr. Connie Page, for without their academic challenges, inquiring appraisals, and invaluable assistance this thesis could not have been completed. I want to thank my parents, for without their financial and caring support graduate school would not have been possible. I also wish to thank the Red Cedar River Federation of Fly Fishers for financial support for the initial phase of this study. I wish to offer my sincere thanks to a myriad of people who assisted me in the field, the lab, and gave me technical assistance: Mark Freeberg, Charles Gowan, Mark Bagdovitz, Martin Smale, Jim Wood, Andy Loftus, Mike Nurse, John Kocik, Doran Mason, Joel Droesch, Kelly Duis, Steve Sobaski, and members of the staff of the Illinois Natural History Survey. Finally, I thank my wife, Dawn, for her love, help, and support throughout each phase of this degree. ii TABLE OF CONTENTS Page LIST OF TABLES........................................... iv LIST OF FIGURES.... ..... ................................. vi LIST OF APPENDICES.......................................vii INTRODUCTION............................................. 1 Description of the River and Study Sites............ 3 NETHODS AND hATERIALS.................................... 10 RESULTS.................................................. 18 Fish Community Composition.......................... 18 Discharge, temperature, and dissolved oxygen........ 20 YOY Rock Bass and Smallmouth Bass................... 23 DISCUSSION............................................... 65 SUNNARY.................................................. 84 LITERATURE CITEDOOOOOOOOOOOOOOCOOCOOOOOOOOOOOOOOOO0...... 86 APPENDIX A..0...0.0.0..OOOOOOOOOOOOOOOOOOOOOO0.0.0.0.0... 94 iii Table 63. 6b. 9a. 9b. LIST OF TABLES Page List of the aquatic plants found in the Vanatta and Sherwood study sites, Red Cedar River, in the summerOf1983..0.0.0....I.OOOOOOOOOOOOOOOOOOOOOO0.0 Bailey fish population estimates for seven 100 meter study sites on the Red Cedar River in AugustOf1982..COO...O0.000000000IOOOOOOOOOOOOO..0. Bailey fish population estimates for Vanatta study site (4D4 meters) and for Sherwood study site (236 meters), Rad cadar River...OOOOOOOOOOOOOOOOOOOOOOOOO. Dissolved oxygen (ppm), temperature (degrees C), and percent oxygen saturation values for emergent vegetation beds (Sgururug cernuug) in the Red Cedar River in the summer of 1983................... Comparison of end of the year numbers of young-of- the-year fish, per meter squared of emergent veg- etation and mean fish total length at Sherwood site. 1983 mean fish densities organized by sampling 19 21 25 26 period and habitat type (#fish/square meter)......3@-31 1984 mean fish densities organized by sampling period and habitat type (#fish/square meter)..... 32-36 Spatial distribution of young-of-the-year small- mouth bass and rock bass within each major habitat type in 1983 and 1984....................... Habitat partitioning by size: mean fish size by species, age, and date in each habitat type 38 sampledOOOOOOOOOOOOOOOOOOOOOOO00.000.000.000...O. 39-40 Daytime associations among larval fish species of the Red Cedar River in 1983, as measured by Forbe's coeff161ent (C£)OOOOOOOOOOOOOOIOOOOOOOOOOO0.0.000... Daytime associations among larval fish species of the Red Cedar River in 1984, as measured by Forbe's COEff1Cient (Cf).....O0..COOOOOOOOOOOOOOOOOOO...0.0. iv 42 43 10a. 10b. 11. 12. 13a. 13b. V LIST OF TABLES (continued) Total numbers of fish in the Sherwood study site based on the number of fish per meter squared in the different habitat types and the total areas of the various habitat types sampled in 1983........... 44 Total numbers of fish in the Sherwood study site based on the number of fish per meter squared in the different habitat types and the total areas of the various habitat types sampled in 1984........... 45 Smallmouth bass and rock bass young-of—the-year population growth rates (u=% change in total length per day) for June through October 1983 and 1984........................................ Number of fish in the diets of resident species in the Red Cedar River in the summer of 1983.... Feeding periodicity data for rock bass 3.80 to 7.19 centimeters total length collected in the Red Cedar River in the summer of 1983........... Feeding periodicity data for rock bass 7.20 to 21.00 centimeters total length collected in the Red Cedar River in the summer of 1983........... 61-62 63-64 LIST OF FIGURES Figure Page 1. Red Cedar River Watershed...... ........ .............. 4 2. Map of the Vanatta and Sherwood study site locations. 7 3. 1983 temperature and discharge....................... 23 4. 1984 temperature and discharge....................... 24 5. Length frequency of young-of—the-year smallmouth 238881?!1984....o.o.......................o.......... 46 6. Mean young-of—the-year smallmouth bass size in millimeters total length in the summer of 1984 1 S.E. 48 7. Mean growth rate of the 1984 young-of-the-year smallmouth bass versus time.......................... 49 8. Mean growth rate of the 1984 young-of-the-year smallmouth bass versus size.......................... 50 9. Length frequency of young-of-the-year rock bass in1983...0.00000000000000000000000IOOOOIOOOOOOOOOOOO 53 10. Length frequency of young-of-the-year rock bass captured in November of 1983 and 1984................ 54 11. Length frequency of young-of-the-year rock bass in1984.00......OOOOOOOOOOOOOOOOOOOOOOOO0..0.......0. 55 12. Mean size of the 1983 young-of-the-year rock bass versus time 1 S.E.................................... 56 13. Mean size of the 1984 young-of-the-year rock bass versus timeI.S.E....O...OOIOOOOOOOOOOOOOOO0.0.000... 57 14. The periods of maximum smallmouth bass spawning in relationship to stream discharge and minimum temperaturEOOOOOOOOOOOOOOOOOO0.000......0.0.0.0000... 68 Vi Appendix Al. A2. A3. A4. A5. A6. LIST OF APPENDICES Mean daily discharge, in cubic feet per second, for the water year October 1982 to September 1983 in the Red Cedar River at the USGS gaging station near Williamston, MI..................................... Mean daily discharge, in cubic feet per second, for the water year October 1982 to September 1983 in the Red Cedar River at the USGS gaging station near East Lansing, MI.................................... Mean daily discharge, in cubic feet per second, for the water year October 1983 to September 1984 in the Red Cedar River at the USGS gaging station near East Lansing, MI.................................... Mean daily discharge, in cubic feet per second, for the water year October 1983 to September 1984 in the Red Cedar River at the USGS gaging station near Nilliamston, MI..................................... Bailey population estimates of the numbers of rock bass in each age class at the Vanatta site (404 meters) in 1983 and 1984 based on October mark-recapture electrofishing data.................. End of the year numbers of young-of—the-year fish per meter squared of emergent vegetation captured by seining at the Sherwood study site and the mean total length of fish captured in zone II by electro- fishing in 1985...................................... vii Page 94 95 96 97 98 99 INTRODUCTION From a preliminary study of the Red Cedar River in the summer of 1982 it was ascertained that both the rock bass and smallmouth bass were important components of the river’s centrarchid complex. As in Linton's (1964) work on the Red Cedar River, the rock bass was the predominant species of the two. Since these two species are often associated in their distribution (Scott and Crossman 1973) and fall into the same feeding guild (Keast 1966), it seems reasonable that the large rock bass population could limit smallmouth bass production. Sanderson (1958) found that growth rates and condition factors of Potomac River smallmouth bass were inversely correlated with the population densities of rock bass and red breast sunfish. Pflieger (1966) suggested that competition between smallmouth bass fry and the young of other fish species might be intense since fry are severly limited in the size ranges of foods available. Other researchers have suggested that competition may ‘not be important in warm-water streams. Hall (1972) and Fisher and Likens (1973) suggested that food is rarely limiting to warm-water stream fishes because most of it is ultimately allochthonous in orgin, and small streams have a net export of energy. Keast (1966) suggested that members of the same feeding guilds, such as smallmouth bass and rock bass, may behaviorally avoid competion by segregating by 1 2 time, place and method of feeding, and size of prey. Since smallmouth bass and rock bass spawn at approximately the same time of year and the young-of-the-year (YOY) occur together in the shallow littoral zones of streams (George and Hadley 1979), I decided to focus my research on the distribution and densities of these two YOY centrarchids in the Red Cedar River, and investigate the factors regulating YOY smallmouth bass and rock bass growth. I hypothesized that the rock bass population was limiting YOY smallmouth bass growth through competition between the young. As a measure of competition between the two species, cohort size and growth rates of both species were followed throughout the spring, summer, and fall. The distribution and densities of these two species in the emergent macrophytes, submergent macrophytes, and open water areas were also investigated to see if habitat partitioning occurred. Supplementary information on predation of YOY smallmouth bass and rock bass by YOY, Juvenile and adult fish, feeding periodicity of the young, and abiotic influences, such as temperature, dissolved oxygen, and discharge, on growth and survival of the YOY was collected. This information was useful in investigating what other mechanisms may be additionally influencing YOY rock bass and smallmouth bass growth. It was hoped that a study of this breadth would indicate what factors may be controlling smallmouth bass and 3 rock bass production in the Red Cedar River, and allow for a further more focused study of these parameters at a later date. Description of thngiverAgnd Study Sites The Red Cedar River is a warm-water stream in the south central portion of the lower peninsula of Michigan. The stream originates as an outflow from Cedar Lake in Livingston County and flows for 49.25 miles in a northwesterly direction before reaching its confluence with the Grand River in the City of Lansing (Grzenda et al. 1968). The headwater drainage is principally marsh or wet land areas. Much of the upper portions of the watershed have been dredged to straighten and deepen the channel for agricultural purposes. Moving downstream, urban influences become increasingly evident with riparian zone elimination, wetland drainage, and municipal development to the waters edge. The Red Cedar River receives the waters of twelve major tributaries, and drains a total area of about 472 square miles (Linton and Ball 1965) (Figure l). The gradient of the main channel is relatively gradual from its source at Cedar Lake, at an elevation 934 feet above sea level, to 817 feet at its confluence with the Grand River, for an average fall of 2.5 feet per mile (Vannote 1963). Two United States Geological Survey (USGS) gaging stations are present on the main channel. The first is located 3.5 miles east of Hilliamston in Ingham County at an altitude of 870 feet. filmy—flak? mgr—~— flcA—WU :9— ; ESQ—..— muzm 2.23am «cap 83:...— c .9 an... mug—.2 a. - l - l l w u¥¢u.. any .. 2.63.3 . on. g. d. A. ¢+h 3 a .. m > _ C If .91?” — M ...... M 0534......) N . .H 0 .. O o» o ”.... .....n. . .l S C 4 ”OSMX. ”...”..Hnus...” $0 a o ... no...“ ... .8........... O V .H 5......“ .8 M. ..H. .P: .... o .....I m. ozazj 9.4.. 2.624.. 5 The second is located 5.6 miles upstream of its confluence with the Grand River on the Michigan State University Campus in Ingham County at an altitude of 824.39 feet (data furnished by USGS field office, Lansing, Michigan). One primary and eight secondary 100 meter study sites were located between these two gaging stations. The secondary locations were used for fish collection sites during the 1982 fish census and several for collections in subsequent years. The primary site was used for the collection of YOY distribution, density, and growth data in addition to fish census data. The highest annual water levels and occasionally serious floods usually occur in the spring of the year during snow melt and spring rains and the period of lowest flow is usually in the late summer or fall of the year (Brehmer et a1. 1968). A record discharge of 8000 cfs was recorded at the East Lansing gaging station on March 24, 1904 (data furnished by USGS field office, Lansing, Michigan). At Williamston a record discharge of 2640 cfs was reached on April 20th during the flood of 1975. A record low flow of 3 cfs was recorded at the East Lansing gaging station on July 31, 1931. Average discharge over a 53 year period at the East Lansing station was 206 cfs and over an eight year period at Williamston it was 102 cfs. October 1982 through September 1984 discharge data for both recording stations are presented in Appendix A, Tables A1-A4. During this time period the maximum, minimum, and mean discharge values at the East Lansing gaging station 6 were 1260 cfs, 12 cfs, and 251 cfs respectively. The values for the Williamston gaging station were 498 cfs, 5.1 cfs, and 95.3 cfs respectively. The primary study site at Sherwood Road was 236 meters long (Figure 2). The downstream portion of this site was characterized by several large snags with associated pools and a sand-silt substrate. Upstream of this was a large sand-gravel run containing large beds of submergent aquatic macrophytes (Vallisneria americana and Saggitaria gag) bordered by beds of emergent aquatic macrophytes (Saururus cernuus). The stream margin contained several large log snags and tree root wads. In the summer months, the upper most section of this study site was a submergent macrophyte choked shallow gravel riffle bordered by a large bed of emergent aquatic macrophytes. In June of 1984, at a discharge of 32 cfs, 23.39 percent of the wetted stream bed in this study site was covered with submergent macrophytes and 5.67 percent with emergent macrophytes. This site's accessibility, presence of submergent and emergent macrophyte beds, presence of large adult rock bass and smallmouth populations, and its use as a centrarchid nesting and nursery area made it an ideal research area. The eight secondary 100 m study sites (Figures 1 and 2) were used for adult population estimates in a preliminary study in the summer of 1982. To allow for comparisons with the results of Linton and Ball's (1965) fish census, I established two of these study sites in their river section II, two sites in section III, and four sites in section IV. Etao£< mzozkcoo stm 6:6 oooBcocm :5. 5.95.9 so... no .2: & ago—... 5.32 are 3— 803.3.5 PH “IP99“ k can :53 3.3: >/ pg uuwneA 32.332 I’ll “”00 II ”VS 3— £03: 8 Site 1 was located about 1/4 mile South of Hatch Road. Site 2 was located at Vanatta Road and sites 3 and 4 were located immediately upstream of Zimmer Bridge. Sites 5 and 6 were located North of Douglas Road just East of Williamston, and sites 7 and 8 were located immediately upstream of the USGS gaging station on Perry Road (M-52). In 1983 and 1984 a 404 meter stretch at Vanatta Road (site 2) was sampled for fish. An aquatic plant survey of the Vanatta and Sherwood study sections was conducted to better describe the vegetative habitat used by larval, juvenile, and adult fishes (Table 1). The emergent aquatic macrophyte Saururus cernuus and the submergent aquatic macrophytes lgllignerig americana and Saggitaria g2; were the species encountered most often. Adding additional structural complexity to the macrophyte beds were large conglomerates of epiphytic and benthic algae. In 1983, Saururus cernuus had a mean summer stem density of 106.86 stems per square meter (S.D.=22.69 N=22). Samplings in 1984 produced a mean summer stem density of 98.86 stems per square meter (S.D.=38.24 N=14). No meaningful stem densities could be calculated for the submergent macrophytes due to the morphology of the vegetation. 9 Table 1: List of the aquatic plants found in the Vanatta and Sherwood study sites, Summer of 1983 EMERGENT FLOATING Sgururugqcernuugr Lemna minor Muhlenbgrqig sp. Phalaris sp. Rumex verticellata Red Cedar River, in the SUBMERGENT Vallisneria americana* Saggitaria ggLi nggtophyllum demersum Drepanoclaggg gg; Elodea canadensis Potamoqgton 89. *-species collectively constituting over 95 percent of the vegetative habitat present in the study sites. 10 METHODS AND MATERIALS In 1982, 1983, and 1984 fish for the mark-recapture population estimates were collected with a 220 volt Homelite direct current generator which sat in an eight foot wooden boat. The three positive hand held electrodes were opposed by a metal negative electrode plate on the bottom of the boat. The five to six man crew started at the downstream end of the site and shocked upstream. The fish were placed in square metal tubs in the boat with freshwater being added frequently to reduce the stress of deoxygenated water on the fish. At the completion of the run, the fish were weighed on a Chatellion 500 x 2 gram dietary scale, measured in millimeters total length (mm TL), and had scale samples taken for age and growth analysis. Centrarchid scales were collected from a point at the anterior insertion of the first dorsal fin just below the lateral line. On the marking runs, fish were given a site and date specific fin clip. All captured fish were released at the downstream end of a study site. At least one to two days were allowed for fish recovery and dispersion between marking and recapture runs. Population estimates and age class estimates were calculated from the mark-recapture data using the Bailey formula (Bailey 1951): N=I.‘L<_C_+ll R+1 where: N = the population or age class estimate M = the number of fish marked on the first run C = the total number of fish captured on the subsequent run R = the number of fish recaptured 11 Variance (V) was calculated using the following equation: V = M'(C+1)(C-R) (R+1)'(R+2) In November of 1983 and 1984 the margins of Sherwood study site were seined for YOY bass. This was done to obtain end of the growing season population size and growth estimates. A swath one meter wide was seined along the margins of the stream in the emergent macrophytes by two biologists. Only the stream margins were sampled because by November the instream vegetation had died and been uprooted and the YOY were concentrated in the emergent vegetation. The seine was 4 feet deep with a 1/4' mesh. Fish that were captured were preserved in 70 percent ethanol and were measured and weighed the next day in the lab. Lengths were recorded to the nearest 0.05 millimeters (mm) with dial calipers and weights were recorded to the nearest hundreth of a gram on an Ohaus top loading Brainweigh electronic balance, model B 300D. From this data, mean November fish size and the number of YOY fish per square meter of shoreline was calculated. Other stretches of the Sherwood study site were sampled with a DC backpack electroshocker. Fish again were preserved, measured, and weighed. These size and number estimates were then compared to the seining results to see if there was any gear size selectivity. The size data was analyzed for similarities between gear types and years. Mann-Whitney U-tests (Siegel, 1956) were run on the mean length data between seining and electrofishing collections for both smallmouth bass and rock 12 bass. This was to see if the collections could be pooled for further analysis between years. A Kolmogorov-Smirnov two sample test (Smirnov 1939) was used to test differences between mean total length data of YOY rock bass collected in 1983 and 1984. Insufficient numbers of smallmouth bass were collected in 1983 to allow for any statistical analysis of mean YOY fish size between years. The primary gear used to collect YOY fish during the summer was a square meter throwtrap. This type of collection gear and its sampling efficiencies are described by Kushland (1981) and by Chubb (1985). My trap was constructed out of 3/8 inch smooth rolled steel rebar, two centimeter wide flat rolled steel for additional support,and the four sides were enclosed with hardware cloth with a mesh size of 6 squares to the centimeter. The trap was 76 centimeters high, and weighed 30 pounds. It was constructed out of steel so that it would fall quickly and be able to withstand a moderate current. In 1983 only submergent and emergent macrophyte beds were sampled. In 1984 open water areas were additionally sampled. In an effort to minimize disturbance of the fish, sampling sites were approached slowly from downstream and the trap was thrown at least 2 meters upstream . Once the trap was on the bottom, the bottom edges were quickly sealed with the surounding substrates to prevent the loss of any fish if the bottom was not level. In the case of emergent vegetation samples, the vegetation was clipped away and stem densities recorded. In the submergent vegetation samples, 13 the vegetation inside the trap was uprooted and rinsed in the trap to assure no fish were trapped in the macrophytes and discarded with the vegetation. Open water areas required no initial manipulation. Fish were removed from the throwtrap with a D-shaped dipnet and a small aquarium dipnet 10 by 6 inches. All large substrate was removed to ensure complete fish removal. Netting was continued until no fish were collected in three consecutive tries. Within each throwtrap sample site, temperature, substrate, water depth, and dissolved oxygen data were collected. The location of each throwtrap site also was mapped precisely by triangulation, described later in the methods. All throwtrap samples were preserved in 95 percent ethanol and taken to the lab for picking. This was neccessary because large amounts of substrate, detritus and vegetation were often collected in the process of netting fish. In gravel samples a sugar flotation method was employed (Anderson 1958). This method was not used in samples containing vegetation or detritus. Fish collected in the throwtrap samples were identified using Auer's (1982) key to the Great Lakes Larval Fishes. Larval fish were routinely dabbed on a paper towel to remove excess moisture and were then weighed to the nearest thousandth of a gram on a Mettler analytical balance. The fish were then briefly emersed in glycerine, to prevent drying out, and placed on a Bell and Howell microfiche reader. This magnified image (24.2X) of the fish was measured and divided by the lens magnification power to arrive at the actual total length . 14 Standard length was also recorded so that a conversion factor from standard length to total length could be calculated and applied to those fish with damaged caudal fins. All fish were identified to the lowest taxonomic level except for minnows and suckers which were identified to family. Throwtrap data were grouped by 7 day periods and the number of fish per square meter was calculated for each species in each habitat type. Grouped data were tested for normality using the test of symmetry for a small sample suggested in Snedecor (1938). Since the frequency distributions were approximately normal, a t-test was used to compare samples. Differences in calculated fish densities within a single week in the various habitat types were tested with a student's two tailed t-test between means of independent samples which do not have the same variance (Gilbert 1976). As a measure of spatial distribution an index of dispersion (I) was calculated (Elliott 1971). This index will approximate 1.0 if there is agreement with a Poisson series, the accepted test for randomness. Associations among larval fish species, for both the 1983 and 1984 data in each habitat type sampled, were described using Forbe's coefficient (cf) (Cole 1949) where: of = (ab-bc)/((a+b)x(b+d) and: of samples where both species were present of samples where only species A was present of samples where only species B was present of samples where both species were absent CLOUD) u "ll" twist 15 Forbes's coefficient values of 0 indicate chance association, whereas values of +1 and -1 may indicate complete association and disassociation, respectively. Total numbers of each species in the Sherwood study site were calculated by multiplying the throwtrap estimates of mean number of fish per square meter in each habitat type by the approximate number of square meters of each habitat type in the study area. The area of each habitat type at low flow was calculated using a Dietzgen compensating polar planimeter, Model D-1805 on a map of the study site drawn to scale. The map was produced from triangulation field measurements. The mapping procedure involved dividing the 236 meter Sherwood study site into 13 sections which allowed for a detailed vegetation and substrate map with limited effort. The location of each throwtrap sample site also was measured and placed on the map. From the weekly grouped throwtrap sample data for YOY rock bass and smallmouth bass, the mean weekly size in millimeters total length was calculated for each species. Their individual growth rates (u), expressed as percent change in total length per day, were calculated using: u = ln TL. - ln TLL t. - t. where: t. TL time (days) total length in millimeters at time t. Linear and exponential equations were calculated with the equation with the best fit to the data being plotted. On July 15th, August 18th, and October 7th of 1983 16 several non study areas were electrofished using a back-pack shocker in order to assess diel feeding habits. Four sampling periods occurred on each date with the first beginning ten minutes prior to sunrise, the second at noon, the third between 6:00 and 8:00 pm, and the forth at midnight. Fish shocked were netted and placed in a chilled alcohol-ice slurry and later transfered to formaldehyde in the laboratory. For each fish collected a length and weight was recorded and the stomach contents were evaluated. When fish were present in the diet the number and species of fish in the gut was recorded. Other food items in the stomach were identified to family when possible and counted. Each gut content was given a subjective numerical degree of digestion as follows: 1)not digested 2)partially digested 3)well digested 4)unidentifiable. From these values a mean degree of digestion was calculated for each time period and date. The mean number of food particles per fish stomach also was calculated for each date and time period. From these two indices it was possible to ascertain the peak feeding times of rock bass and smallmouth bass. In addition, YOY smallmouth bass collected in the 1984 throwtrap samples were examined for fish in their stomachs and the degree of digestion of their gut contents. Temperature and dissolved oxygen data were collected using a Taylor minimum-maximum temperature thermometer, a YSI temperature, conductivity and salinity meter, a YSI dissolved oxygen, temperature meter, and a pocket hand held 17 thermometer. Discharge data were taken from USGS gaging station records at Williamston and East Lansing. Additional discharge data were collected at the Sherwood study site on three occasions at three different flows so that a site specific discharge relationship could be established with the USGS data. A Price—pigmy current meter was used for this data collection. The change in discharge between Williamston and Sherwood was 29.84 percent of the change in discharge between Williamston and East Lansing. This was used to build a predictive equation for discharges at Sherwood site: D. = C(D¢|_ "' Du) '°’ Du where: D. = predicted discharge at Sherwood site Du = discharge at USGS station in Williamston DgL = discharge at USGS station in East Lansing C = a constant .2984 18 RESULTS Fish Community Composition In the summer of 1982 a mark-recapture census of the Red Cedar River fish populations was conducted, by electroshocking seven 100 meter sites, between East Lansing and Webberville (Figure 1). In this preliminary study the greatest number of rock bass (205131) per 100 meters of stream was located at site 4 followed in decreasing order of abundance by sites 8,7,3,1,5, 6 (Table 2). The largest number of smallmouth bass (Micropterug dolomieui) (24115) was located at site 1. All other sites each contained less than five smallmouth bass of any size. Green sunfish (Lepomis cyanellus) were most abundant at site 7 and pumpkinseed sunfish (Lepomis gibbosus) at site 8. The rest of the centrarchid complex, which had been previously documented in the Red Cedar River in earlier studies, were found infrequently (largemouth bass (Micropterug salmoides), the bluegill (Lepomig macrochirug) and the longear sunfish (Lgpomig mquloti§)) or not at all (black crappie (Pomoxis niqromaculgtgg) and warmouth (Lepomis gulosus)) in 1982. The black crappie was located in subsequent years of the study but the warmouth was never found within my study sections although it does exist in Lake Lansing, one of the lacustrine habitats within the watershed. The northern pike (Esox luciug) was found in greatest numbers at site 7. In October of 1983 and 1984 a 404 meter stretch of stream at Vanatta Road was shocked. A 236 meter stretch of stream adjacent to Sherwood road was additionally Table 2: SPECIES RB SMB GSF LMB PS BG LE NP SPECIES RB SMB GSF LMB PS BG LE NP nf=not found, SMB=smallmouth bass, PS=pumpkinseed sunfish, sunfish, Bailey fish population estimates for seven 100 meter study sites on the Red Cedar River in August of 1982 MACKINAC Site 1 111:35 24:15 no est 3:2 no est no est no est no est DOUGLAS Site 6 42:22 nf 3:0 3:2 6:4 2:1 nf nf ZIMMER Site 3 124:33 2:1 24:15 2:1 nf nf nf nf PERRY Site 7 127:34 2:1 145:44 nf 5:2 5:0 nf 5:0 (: 95% confidence interval). ZIMMER DOUGLAS Site 4 Site 5 205:31 58:32 1:1 3:2 nf 4:2 2:0 nf 3:0 3:2 1:1 2:1 nf nf 3:0 1:0 PERRY Site 8 180:54 nf 10:0 nf 24:12 1:0 nf 3+0 no est=no estimate attempted, RB=rock bass GSF=green sunfish, LMB=largemouth bass BG=bluegill sunfish, NP=northern pike LE=longear 20 electrofished in October of 1984. The Sherwood Road site estimates present a partial picture of the community structure and composition for this section of the river (zone II) minus the cyprinids and catostomids for which no estimates were made (Table 3). Comparison of the 1983 and 1984 Vanatta Road site data show an increase in the estimated number of smallmouth bass in 1984 which was directly attributable to a preponderance of YOY. The estimated number of adult smallmouth bass declined however. The rock bass estimate was larger because of a great number of age 1+ fish surviving from a successful year-class in 1983. Although Vanatta Road site was larger than Sherwood Road site, fewer fish were found at the Vanatta Road site in 1984. This was most likely due to the substrate differences and the sites subsequent lack of instream submergent vegetation and its associated food resources. The Vanatta road site substrate was predominately sand and was frequently shifting and vulnerable to scouring not favoring plant attachment. Discharge, temperatureL and dissolved oxygen In the spring of 1983 as discharge decreased, water temperature was increasing. By June 11 discharge had fallen below 200 CFS and the temperature was exceeding 65 degrees Fahrenheit. Nesting activities for both rock bass and smallmouth bass had begun. On June twenty-seventh, the Red Cedar River began rising to flood proportions, peaking on 21 Table 3: Bailey fish population estimates for Vanatta study site (404 meters) and for Sherwood study site (236 meters), Red Cedar River (: 95% confidence interval). SPECIES VANATTA VANATTA SHERWOOD OCTOBER 1983 OCTOBER 1984 OCTOBER 1984 rock bass 387:82 694:218 1374:137 smallmouth bass 132:39 268:56 758:149 YOY smallmouth bass 55:23 232:48 728:167 green sunfish 285:110 81:22 77:47 black crappie 3:0 nf 1:0 longear sunfish 48:18 10:5 2:1 bluegill sunfish 53:25 1:0 2:0 largemouth bass 23:7 14:7 10:5 pumpkinseed sunfish nf nf nf northern pike 2:1 nf 5:0 yellow bullhead nf 2:0 15:7 black bullhead nf 2:0 6:4 yellow perch 3:1 nf nf rainbow darter no est no est 667:376 johnny darter no est no est 425:292 blackside darter no est no est 983:477 nf=none found no est=no estimate attempted 22 June twenty-ninth (Figure 3). In the spring of 1984 there was both a gradual temperature rise and a gradual discharge decline with no late spring flood (Figure 4). Associated with the flood of 1983 was a corresponding flushing of the stream. Early morning low dissolved oxygen values in the emergent macrophyte beds changed from 3.83 PPM during pre-flood conditions to 6.98 PPM following the flood (Table 4). From June 15th to September 13th 1983, mean maximum and mean minimum water temperature values were 25.05°C (S.D.=1.34) and 21.04°C (S.D.=1.44) respectively. In 1984 during the same time period, mean maximum and minimum stream temperatures were lower than in 1983, with values of 22.64°C (S.D.=3.38) and 15.65°C (S.D.=2.38) respectively. YOY:Bock B§§§_§nd Smallmouth Ba§§_ Comparing the November seining data between 1983 and 1984 (Table 5) it is evident that more YOY rock bass were present per square meter in the fall of 1983. 'It is also apparent that in 1984 more smallmouth bass per square meter remained in the fall than in 1983. I feel the seining data more adequately reflects the true YOY rock bass densities in 1984. When electrofishing many rock bass are stunned but due to their cryptic coloration can not be seen in the vegetation and leaf packs and thus are not captured. I feel the YOY smallmouth bass densities in 1984, on the other hand, are more accurately described by electroshocking. Only the smaller, smallmouth bass were captured by seining, 23 max—1:029 92d. mu—DPém—mzmh. mam: an mum—DU?— Am>4“: HZDn m 0.0.... . '10.... m '61.. a. 3...... own... an .... 2...: W .... m a... m .. . .. . .. m . . .. .. ...... . .. ... .. m ... u ... .. v m . .... °.. an . .... .... .. 0 .. . .— ... so. ( ( .. >\< 239.53%...” on >.==. HZDH >O> Z52. 3 o— HZDH on K on 2 N- n V VNO m .2. 393m .— N. E 2 m— .N «N E ...... .... "a m on I. an O vm on on ow NV 3V 3. . 8.6”". e. noéthhnoé+onmhpnofim . 49 ”=2: mama?» mmO> vamp HIP mO 95E IHBOKU Z1— 2. M755 _ _ 4J____323H~4 mm Vm 0m 2 S v 8 mm mm «L 9 z m ow mm 5 b 2 a c.._ ..._.__ ......_.... ... ._4..___.7343 885 “N. 3.5.: mwhodlownmdlngufi 36:... veno.o1vn~.o.wlua=v=_ 11111! p Sduw. N 111111111111111 ‘ a: O N 0 1111111 c'> It) I!) O I I O O V O l r l r O to V O REE: vowed 1 awful u A3:— ELLVM HLMOXD 50 MN; m2m¢m> mmO> 32. ME “—0 “=2: IP30¢D Z wmO> 8a.. 5:. m0 MN; 25:2 "up ”.520: ”:7. >42. ~22. mumuwuhwnwmmwmuvuowopuwcvonouuu wad ”N.— W AUEFC—ONO.O1T whoa. — H AHCE I On 57 .m.m .32: mamas.» mm: 3.62. .5» 32 a: so was z52. mza. m m quvucumwuwc vwnhunumwmp 3h nmNmN._N_hw wmduflu Aosgbmwnvd 1560—...” Ah ... OO'OQNO 58 -0.11 respectively. Insufficient data were present to divide the cohort into discrete spawning intervals which might have allowed for better growth rate-size and growth rate-time relationships. In November of both 1983 and 1984 YOY rock bass were collected by seining and used to calculate their growth rate between the time they were 8.00 mm total length and the end of the growing season. As mentioned previously the rock bass in November 1984 were slightly larger than those in November 1983 and there were less fish in 1984 than in 1983 (Table 11). The growth rates in both years were nearly equal with the 1984 rate being slightly greater. In an effort to ascertain the degree to which predation may govern smallmouth bass and rock bass interactions in the Red Cedar River, three twenty-four hour backpack shocking collections were made in the summer of 1983 for subsequent stomach analysis. A total of 278 stomachs of 12 resident species were examined for the presence of fish in their diets. Only in the stomachs of smallmouth bass, largemouth bass and northern pike were fish found (Table 12). The northern pike stomachs contained cyprinids. One smallmouth bass 8.0 cm TL contained two YOY rock bass and one 9.8 cm largemouth bass also had fed on one YOY rock bass. To further investigate the impact of smallmouth bass YOY on rock bass YOY populations, seventy-seven YOY smallmouth bass collected in throwtrap samples between August 1st, 1984 (mean TL=39.4 mm, SD=4.25) and October 2nd, 1984 (mean TL=56.4 mm, SD=5.05) were examined for larval 59 Table 12: Number of fish in the diets of resident species in the Red Cedar River in the summer of 1983 SPECIES # OF STOMACHS # OF FISH IN EXAMINED THE STOMACHS Rock bass 189 0 Pumpkinseed sunfish 3 0 Bluegill sunfish 1 0 Green sunfish 17 0 Longear sunfish 3 0 Smallmouth bass 17 2 YOY RB Largemouth bass 4 1 YOY RB Blackside darter 7 0 Rainbow darter 6 0 Johnny darter 2 0 Cyprinids 27 0 Northern pike 2 2 CYPRINIDS YOY RB=young-of-the-year rock bass an! AA VU.‘ Niv—u ans-+1 9 O n l] .1‘ Cl 4') ~11: 60 fish in their guts. None of the stomachs contained any fish and most contained microcrustaceans, and small emphemeropterans, dipterans, and hemipterans. In 1983 a sample of 16 smallmouth bass ranging from 66 mm TL to 156 mm TL, (mean TL=83.18 mm, SD=45.49) were collected and examined to ascertain when peak feeding occurred. The data indicate that smallmouth bass fed primarily at sunrise and just prior to sunset. Fish also fed during the day with only 20% of stomachs examined being empty. At night 80% of the stomachs examined were empty and gut contents were well digested in those that weren't empty. The data suggest that smallmouth bass forage in hours when there is light. Throwtrap data implies that rock bass remain in cover during the day. One hundred fifty rock bass stomachs collected in 1983 were examined to ascertain peak feeding times (Tables 13a and 13b). In almost all cases the number of empty stomachs and the mean degree of digestion were greatest during the daylight hours and least during the night. This suggests that rock bass feed primarily at night. 61 Table 13a: Feeding periodicity data for rock bass 3.80 to 7.19 centimeters total length collected in the Red Cedar River in the summer of 1983 7/15/83 Sampling time N f of empty guts Mean # of food items per fish stomach 15E I of organisms ingested Mean degree of digestion SD 8/18/83 Sampling time N # of empty guts Mean # of food items per fish stomach :SE 0 of organisms ingested Mean degree of digestion SD SR(6:13AM) 6:05AM 6 0/6 13.17 :2.82 79 SR(6:48AM) 6:35AM 1 0/1 18.00 NOON 11:35AM 6 0/6 6.50 10.99 39 NOON 12:00 0/1 10.00 SS(9:14PM) 6:47PM 2 0/2 30.50 124.50 61 SS(8:35) 6:27PM 3 0/3 11.00 :4. 16 33 MID 11:33PM 5 0/5 12. 20 11. 62 61 2.70 0.901 MID 12:00 0/2 15. 00 _+__4. 95 Table 13a (cont'd.) 62 10/7/83 Sampling time N O of empty guts Mean # of food items per fish stomach 15E # of organisms ingested Mean degree of digestion SD SR(7:42AM) 7:30AM 8 0/8 19.75 16.42 158 NOON 12:50PM 10 0/10 5.70 10.99 57 SS(7:10PM) 7:30PM 13 0/13 5.54 11.20 72 MID 12:50AM 7 0/7 9.71 12.14 48 SR=sun rise, SS=sun set, SE=standard error AI ME ‘0 ‘- -1 ul 63 Table 13b: Feeding periodicity data for rock bass 7.20 to 21.00 centimeters total length collected in the Red Cedar River in the summer of 1983 7/15/83 Sampling time N # of empty guts Mean # of food items per fish stomach 15E # of organisms ingested Mean degree of digestion SD % with crayfish 8/18/83 Sampling time N # of empty guts Mean # of food items per fish stomach 15E 0 of organisms ingested Mean degree of digestion SD X with crayfish SR(6:13AM) 6:05AM 5 0/5 7.20 11.39 36 SR(6:48AM) 6:35AM 8 0/8 6.38 10.53 51 NOON 11:35AM 6 0/6 3.83 10.75 23 NOON 12:00 1/5 1.40 10.51 SS(9:14PM) 6:47PM 8 1/8 1.50 10.33 11 1.104 37.5 SS(8:35) 6:27PM 4 1/4 1. oo 10. 58 MID 11:33PM 6 0/6 9.50 ‘11.06 56 MID 12:00 0/2 6.50 15.50 13 64 Table 13b (cont'd.) 10/7/83 SR(7:42AM) NOON SS(7:10PM) MID Sampling time 7:30AM 12:50PM 7:30PM 12:50AM N 5 6 6 5 # of empty guts 0/5 1/6 2/6 0/5 Mean # of food items per fish stomach 15E 4.40 2.83 2.67 4.20 12.11 10.79 11.71 11.99 t of organisms ingested 39 17 16 21 Mean degree of digestion 2.31 2.88 2.44 2.19 SD 1.004 1.111 1.094 1.167 % with crayfish 0 33.3 33.3 40 SR=sun rise, SS=sun set, SE=standard error 65 DISCUSSION The Red Cedar River has been the source of many studies documenting the changes in its biotic and abiotic parameters in the past 25 years. Over this time period upgraded wastewater treatment has resulted in decreased addition of biodegradable organics to the river, but because of increased urbanization in the basin, no net reduction in the nutrient load carried by the river has been realized (Burton and King 1983). Water quality appears to have been degraded substantially in the upper portion of the river since the 1960's but to be essentially unchanged in the lower areas in the face of increased upstream loading. Macrophyte biomass production of the entire river appears to have decreased to values typical of pre-1958 conditions (Burton and King 1983). During the 1961 and 1962 seasons, Vannote's (1963) experimental study reach was approximately 50 percent covered with aquatic macrophytes. At the midpoint of Vannote's study site lies my Sherwood study site. In 1984, 29 percent of my study reach contained macrophytes. Burton and King suggested that such decreases could be related to changes in point-source inputs, but they felt it much more likely to be related to the flushing of silt out of the river as a consequence of high flows in the years 1968, 1969, 1975, and 1976 that exceeded average discharge. Comparisons of the fish populations in the Red Cedar River in the 1960's and in this study only show a few small changes. In the 1960's the fish populations were studied 66 and documented by Linton (1964; 1967) and Linton and Ball (1965). Since the sites sampled by Linton and by myself each had their own intrinsic habitat quality and carrying capacity, direct numerical comparisons of fish between zones was not attempted. However, species trends between zones for the two studies were compared. In comparisons between Linton's dry weight production of species of fish and my population estimates of each species in selected sections of zones II, III and IV, it appears that the rock bass has now become as abundant in zone IV as it was in zone II and III. Zone II still contains the best smallmouth bass population. As in Linton's study, smallmouth bass production readily fell off upstream of zone II. Green sunfish numbers are greatest in the upstream section of zone IV followed by zone II. Linton found the greatest production of green sunfish in zone II. In Linton's study pumpkinseed production was greatest in zone IV. In this study the greatest numbers of pumpkinseeds were also found in zone IV. It appears that the centrarchid populations in zones II and III have not dramatically changed in structure from that documented by Linton in the early 1960's. Zone IV has shown an apparent increase in green sunfish and rock bass. This could be a result of the loss of the reservoir and dam at Hillamston. The loss of the reservoir and its lentic environment, may also explain why no crappie or warmouth were collected in zone IV in the current study. In general, the most abundant fish in the Red Cedar River, other than minnows and darters, is and was 67 the rock bass. Aside from historical comparisons, this study served to investigate the early life history and behavior of the rock bass and the smallmouth bass and the causes for year class fluctuations in these two species. Emig (1966) summarized data showing that smallmouth bass move into spawning areas at temperatures from 4.4 to 15.6 degrees Celsius, and spawning activity commences at temperatures from 14.4 to 21.2 degrees Celsius, but a drop in temperature will cause nesting to stop. Scott and Crossman (1973) stated that nest building and spawning commences over a range of temperatures 55 °F to 68°F (12.8°C to 20.0°C) but egg deposition takes place mostly at 61°F to 65°F (16.1°C to 18.3°C). Stability of water levels in spring and early summer is necessary for successful spawning of smallmouth bass (Watson 1955). In the Red Cedar River the stimulus to begin nest building also appears to be temperature related. Both the rock bass and the smallmouth bass usually spawn in mid May to late June when the water temperature exceeds 12.7°C. High stream discharges may deter spawning (Vannote 1963). In 1960, 1961, and 1962, smallmouth bass spawning was delayed until stream flows were less than 200 cfs in Vannote's study site (Figure 14). Smallmouth bass spawning began during a period of rapid temperature increases. Vannote suggested that the 1960 spawning season was delayed apparently by a period of high to moderate, fluctuating stream discharge. The 11 percent to 15 percent failure of smallmouth bass 68 DISCHARGE (cfs) MINIMUM STREAM TEMPERATURE (“E1 FIGURE“: THE PERIODS OF MAXIMUM SMALLMOUTH BASS SPAWNING IN RELATIONSHIP TO STREAM DISCHARGE AND MINIMUM TEMPERATURE from Vannote (PhD,1963) 69 nests in 1961 and 1962 respectively, was attributed to low water temperatures following early spawning attempts (Vannote 1963). The 1961 temperature and discharge graph compares well with the 1984 temperature and discharge graph (Figure 4). According to Vannote, large bass invariably were the first spawners each year, and nesting attempts during the early favorable temperature periods were most vulnerable to subsequent low temperatures. In 1960 Vannote estimated an 85 percent failure of smallmouth bass nests. This data compares quite closely with my 1983 data. In 1983 the smallmouth bass either experienced a high nest failure or were subject to high mortality immediately following swim-up due to a large spate in late June (Figure 3). From literature values in Carlander (1977) I calculated that from nest building to swim-up would take a minimum of twelve days and a maximum of fifteen days. Therefore in 1983 fry were predicted to swim-up between June twenty-second and the twenty-fifth. On June twenty-seventh, only two to five days after predicted swim-up, the Red Cedar began rising to flood proportions peaking on June twenty-ninth. It is probable that this spring flood was what attributed to the poor smallmouth bass year class produced in the spring of 1983 in contrast to a much better one in the spring of 1984 during a gradual temperature rise and a gradual discharge decline. A successful smallmouth bass nest will normally produce about 2000 fry (Scott and Crossman 1973), although the range can extend from 500 to 11,000 (Carlander 1977). Cable (1973) stated that counts of smallmouth bass fry in nests 5'; 70 have ranged from 1000 to 5000 in studies by Doan (1940), Surber (1943), Sanderson (1958), Latta (1963), and Pflieger (1966). Vannote stated that 3000 fry were produced per successful nest in the Red Cedar River. My calculations concur with his estimate. As is apparent, one of the most important characteristics of warm water streams, at least as far as the fish are concerned, is their tendency to fluctuate unpredictably in flow from season to season and from year to year (Moyle and Li 1979). Vannote (1963), Cleary (1956), and Surber (1942) among others, have singled out stream stage as the major factor in determining year class strength. The varability in year class strength is Primarily the result of these unpredictable changes in the stream environment, which can favor one species over anOther. Differences in time of spawning were considered by StaI-‘rett (1951) to be one of the major reasons the species c":""I'->c1sition of the river showed considerable fluctuation from year to year. The fluctuations are related to the timing of floods and periods of low flow, which can occur at any time during the growing season. The floods wash away 9998 and young (Larimore 1975). Larimore indicated that destruction of the reproductive resmalts was a complex relationship between several factors. water temperature, velocity, turbulence, and turbidity are the primary environmental factors that change when 'ar‘M-water streams are flooded. Water temperature usually drOpa because most spring floods come with cool, cloudy 71 weather. Low temperature may not kill the fry but reduces their swimming ability (Larimore and Duever 1968). Webster (1948) demonstrated that thermal changes over a 30 minute period from 65 degrees to 75 degrees Fahrenheit or from 65 degrees to 50 degrees Fahrenheit caused no appreciable mortality on YOY smallmouth bass. Larimore and Duever explained that temperature changes may not directly cause the displacement of smallmouth bass fry, but the reduction in swimming ability associated with declining temperatures contributes to displacement of fry exposed to other physical changes accompanying flood waters. Loss of orientation may account for the frequent disappearance of entire year classes of fry from warm-water streams. The delayed maturity/large size pattern is most characteristic of piscivores such as the smallmouth bass. These fishes usually do not spawn before their third summer of life and depending on size and species, produce 5,000 to 140,000 eggs per female (Moyle and Li 1979). The advantage of this life history strategy is that it allows a species to persist in some numbers even though periods when conditions for reproduction are unfavorable and to invest most of the energy ingested in the first two or three years into somatic growth rather than reproduction. If energetically and physiologically it is possible for a given fish, more than one distinct spawning period can occur in a given year. This is generally observed when the initial period has been disrupted in some manner. Males have been observed to participate in several spawnings under natural conditions ht 72 (Brown 1960; Pflieger 1966; Coble 1975). Inslee’s (1975) report of multiple spawnings by individual smallmouth bass females in hatchery ponds indicates that such behavior may be possible in natural populations. No such second spawning of smallmouth bass was seen in the Red Cedar River following the spate in 1983. Lack of additional spawning after a flood may be potentially a function of sexual regression (Shuter et al. 1980). A factor which could stimulate this regression in males was proposed by Brown (1960). Because some suppression of feeding appears to be a concomitant of sexual activity in males (Heidinger 1975), the longer the breeding season and the higher the temperatures experienced, the greater the degree of starvation suffered by fish. It is conceivable that if sufficient stress is imposed on males through this mechanism, the production of sexual hormones may cease, thus permitting resumption of feeding and presumably initiating gonad regression and ending sexual activity. The rock bass in 1983, unlike the smallmouth bass, succeeded in producing a large year class. This year class was even larger than the one produced in 1984, a year with a stable discharge and temperature record. The rock bass appears to be more physiologically and evolutionarily adapted to such a harsh and unstable environment. This species is classified by Moyle and Li (1979) as to having a moderate size/maturity time pattern. Fecundities range from 2000 to 25,000 eggs. Due to its smaller egg production relative to the smallmouth bass and smaller growth rates, 73 the rock bass is therefore capable of spawning at a smaller size and age than the smallmouth bass. It is also more capable of multiple spawnings, perhaps an evolutionary adaptation to living in a harsh and fluctuating environment. Gross and Nowell (1980) indicated that twenty-four percent of the males in Lake Opinicon, Ontario spawn more than once during the summer. Females can also spawn again, as indicated by modal egg classes noted in the ovary. In 1983 in the Red Cedar River, the rock bass re-commenced spawning activities following the spate and continued on into early August. In 1984 rock bass spawned from mid June to mid July. It is perhaps this ability to continue spawning after a .flood that makes the rock bass the most abundant centrarchid in the Red Cedar River. The question arises however, why were more YOY rock bass produced in 1983, a spring with a major flood, than in 1984 a spring without a flood? Several reasons are possible. The first involves the rock bass unsuccessfully competing with the large numbers of smallmouth bass in 1984 in contrast to 1983 when the smallmouth bass were found in extremely low numbers. Growth rate analysis of the fish collected via drift net and throwtrap samples indicates that in 1984 the rock bass actually exhibited a slightly better growth rate than in 1983 thus indicating that competition with YOY smallmouth bass wasn't controlling year class size. Water temperature is an equally plausible reason for the differences in the 1983 and 1984 rock bass year class sizes. Raney (1965) stated that rock bass spawning is 74 initiated when the water warms to 20.5 °C and may continue up to 26 °C. It appears that water temperatures in 1983 may have been closer to the preferred spawning temperatures and lasted longer than in 1984. Throughout the summer of 1984 water temperatures routinely fell below 20.0 °C at night. Only during the spring flood in 1983 did the water temperatures fall below 20.0 °C. Another possible reason for the larger 1983 rock bass year class involves the differences in the total number of adult rock bass present in both years. In 1983, according to the population estimates made from the electrofishing data, there were roughly four times the number of reproductive adult rock bass in the primary study sites than in 1984 (Appendix A, Table A5). According to Hile (1961) both male and female bass in Wisconsin are mature at age II and spawn the next spring at age III. Table A5 indicates that there were 221 reproductive rock bass in 1983 at the Vanatta site and only 50 in 1984. This alone could account for a good portion of the variation in rock bass year class sizes produced. Macrophyte growth in the Red Cedar River is timed well with larval fish production. This is critical due to its importance as cover for larval fish. Throwtrap collections of YOY smallmouth bass and rock bass indicated their affinity for the instream submergent vegetation. Unlike many other studies where YOY smallmouth bass were segregated on a habitat axis (Wickliff 1920; George and Hadley 1979) these species were found in highest densities in the Red 75 Cedar River in the same habitat type. YOY smallmouth bass also utilized open water and rock bass also utilized the emergent vegetation. Studies of microhabitat preferences of warmwater fishes indicate that most species are quite flexible in this regard, and the degree of microhabitat specialization of a species may change in response to the number and kinds of other fishes present with it as well as the life history stage (Gee 1974; Mendelson 1975; Smith 1977). Macrophyte growth in the Red Cedar is seasonal. The maximum production rate is attained by late June and rapidly diminishes thereafter (Vannote 1963). The total growing season is approximately 125 days. In mid-September large segments of the submergent macrophyte crop detach from the rooted portion and drift downstream. By the end of September virtually the entire community has detached. The YOY bass at this time become concentrated along the margins of stream in the dead, matted down, emergent macrophyte stalks. A variety of studies suggest that prey vulnerability decreases as environmental complexity increases (Huffaker 1958: Glass 1971: Stein and Magnuson 1976; Saiki and Tash 1979). In a lab experiment predation success (number of captures) by largemouth bass was similar at 0 to 50 stems per square meter, declining to near zero at 250 and 1000 stems per square meter (Savino and Stein 1982). Emergent vegetation in the Red Cedar River had a stem density of approximately 100 stems per square meter and the instream 76 vegetation's stem density was greater. In Savino's study as stem density increased, predator activity declined due to a decrease in behaviors associated with visual contact with prey. Cooper and Crowder (1979) also felt that vulnerability could be reduced in vegetation simply because random visual encounters between predator and prey are reduced. Reduced predation success by largemouth bass in habitats of increased complexity apparently is related to increases in visual barriers provided by plant stems as well as to adaptive changes in prey behavior. In the Red Cedar River, the smallmouth bass is the most predominant piscivore. Stomach analysis of the smallmouth bass indicates that they do feed on YOY rock bass that may have strayed from the protection of the macrophyte beds. Brown (1984) in lab experiments showed that rock bass fry, which do not have the benefit of a guarding parent after they leave the nest, avoid all sizes of predators sooner than largemouth bass and must depend on avoidance plus other tactics such as freezing and hiding in vegetation to avoid a predator successfully. Gross and Nowell (1980) noted the ability of rock bass larvae to swim into the nest substrate when disturbed during a predatory assult. In the vegetation beds immobilization (Smythe 1970: Curio 1976) combines with cryptic coloration (Endler 1980) to permit prey to blend in with the background and avoid detection by visual predators. Predation may be a major cause of death in warm-water stream fishes, but its significance in determining community atI‘ucture is difficult to assess because environmental 77 influences may mask its effects. The role of predation in shaping the fish community is perhaps best reflected in the life history patterns evolved by the fishes, as well as in distributional and behavioral patterns commonly observed. Predation appears to serve as a strong force regulating YOY rock bass behavior from an evolutionary standpoint. Prey species and sizes, such as the YOY rock bass, that are most vulnerable to predation tend to associate most closely with structure (Crossman 1959; Charnov et al. 1976: Stein 1977; VanDolah 1978). As mentioned previously the YOY rock bass remained hidden in the vegetation beds during the day. Stomach analysis of the smallmouth bass indicated that this species foraged primarily during the early morning, evening, and some during the day. At night 80 percent of the stomachs examined were empty. Munther (1970) observed no movement by smallmouth bass in his river at night and in the laboratory his smallmouth bass fed during the day and went on or beneath the substrate during darkness. The rock bass was shown by Spencer (1939) to swim both during the day and night in the absence of a predator. Keast and Welsh (1968) investigating the daily feeding periodicities of rock bass, (100 to 170 mm) showed that there were two peaks in weight of stomach contents per gram of fish, one extending from about 9 PM to 1:30 AM and the second about noon. Spoor and Schloemer (1938) also noted the diurnal activity of rock bass in Muskellunge Lake. Activity in the rock bass peaked between 7 and 9 PM with the fish remaining relatively active throughout the night and showing only a slight increase in 78 activity between 3 and 4 AM. The rock bass in the Red Cedar River showed a feeding peak around sunset and sunrise. They also fed during the night but feeding was always suppressed during the day. Keast (1977) indicated that most of the small age O and 1 fish hide by day in rock crevices in the shallows, and feed along the water’s edge at night often in water only a several centimeters deep. Zaret (1979) indicated that behavioral accommodation may occur when species such as the YOY rock bass are under predatory pressure. Studies have indicated that prey fish populations under intense predation pressures will evolve different behavioral patterns from populations of the same species under different predation pressures, and that this behavior is heritable (Seghers 1974a, 1974b). This could explain the nocturnal behavior of the rock bass. Throwtrap results also indicated that the YOY rock bass, although utilizing the same primary habitat as the YOY smallmouth bass, may be actively avoiding the smallmouth bass due to predatory pressures. Forbes coefficients and regression analysis between the two YOY species were consistently negative, although only to a slight degree. YOY smallmouth bass also have evolved mechanisms to reduce predational losses. In Illinois smallmouth bass were observed returning to the nest site at night and being actively guarded by the male. If mortality is low on these young, intra-specific competition could greatly suppress growth rates. In the Red Cedar River, in 1984 a large year class of smallmouth bass was produced. These fish showed a 79 much diminished growth rate in comparison to 1983 a year with a smaller year class. The 1984 year class was also much shorter at years end than was the 1985 year class (Appendix A, Table A6) which like 1983 was relatively sparse. From our limited data it appears that growth of the YOY smallmouth bass is highly correlated with cohort density. This has been noted in several other studies. Coble (1971) showed that smallmouth bass growth in a series of ponds was inversely related to population density. Hubbs and Bailey (1938) noted slow growth with high population density. The more abundant year classes in Lake Michigan also showed slower growth (Latta 1957). However, unlike Sanderson (1958) who found that growth rates of Potomac River smallmouth bass were inversely correlated with the population densities of rock bass and redbreast sunfish, the Red Cedar River data showed that YOY smallmouth bass growth rates appear to be unrelated to YOY rock bass population size. George and Hadley (1979) stated that the faster growth of smallmouth bass produced size differences between the two species which increased with time. The size differences presumably reduce resource sharing by enabling smallmouth bass at any given time to catch larger prey than the rock bass. Smallmouth bass growth rates are not strictly density dependant however. They could be partially temperature dependant. Laboratory studies of YOY smallmouth bass and yearlings have shown that optimum temperature for growth is between 25 and 29 °C (Maclean et. al. 1984), and that growth 80 ceases at 35 °C (Rowan 1962; Peek 1965; Morning and Pearson 1973). Doan (1939) demonstrated in Lake St. Clair that growth in total length of the bass fry was reduced when drops in water temperature occurred from 22.8°C to 14.7°C between June 17th and June 20th. In the Red Cedar River in 19823 mean maximum and mean minimum temperatures for June 15th through September 13th exceeded the values recorded for 1984. Thus the better growth rate of the 1983 year class, and the poorer growth rate of the 1984 year class could in part be a function of these temperature differences. Fry and Watt (1957) demonstrated that initial year class strength of smallmouth bass was directly related to ternperature from July through October of the first year of life. Percent oxygen saturation may also have attributed to the differential YOY smallmouth bass population growth rates 3991': between the 1983 and 1984 year classes. The prolonged B‘31".7Lng flooding in 1983 flushed the stream of autochthonous anti allochthonous materials effectively reducing the a"II-”3.3Litude and duration of low dissolved oxygen periods. This, coupled with warm stream temperatures in 1983, peruced a higher daily average percent oxygen saturation than those of the system in 1984. This in its self could have induced greater growth rates in 1983. In 1984 the att‘eam only experienced one short increased discharge event t0 act as a reset mechanism, and had a lower average summer water temperature than in 1983. Stewart et al. (1967) ihvestigated the influence of oxygen concentrations on the 81 growth of juvenile largemouth bass and found that growth and consumption rates increased with increases in dissolved oxygen to levels near saturation and declined with further increases of oxygen concentration. They also noted that growth of bass subjected alternately to low and high concentrations of dissolved oxygen for either equal or unequal portions of 24 hours was markedly impaired. Andrews et al. (1973) studied the influence of dissolved oxygen on the growth of channel catfish, Ictalurua punctatus. Growth rates of fish maintained at 36% air saturation were approximately half that of fish maintained at 60 and 100%. Chronic effects of low dissolved oxygen concentrations on the fathead minnow were studied by Brungs (1971). Fathead Minnows were exposed to constant dissolved oxygen concentrations (1.0 - 5.0 mg/liter) for 11 months. Fry growth was reduced significantly at all concentrations below the control of (7.9 mg/liter). Regardless of whether it is biotic or abiotic mechanisms that control growth, it is evident that the EmaIleouth bass populations have differential growth rates bet‘seen years and within the same cohort during the same Year. Individual fish may vary markedly in their growth rates, even under controlled conditions, leading to a broad size distribution among even-aged fish (DeAngelis and CO‘J‘tant 1979). Size variations within a population of first-year fishes can have significant effects on the noIZDulation dynamics and the ultimate number of adult 1‘ E5C3ruits, because these variations influence competitive and 82 cannibalistic relationships within species as well as predator-prey relationships among species. Wismer et al. (1985) suggested that YOY fish are spawned over a finite time period and are exposed to spatially and temporally changing physical conditions and food availabilities. It is thus unrealistic to expect that sizes of individual fish in a cohort will be even approximately the same at the end of the first year of growth. Typically a cohort contains a broad distribution of sizes. This was true for the smallmouth bass due to differential genetic growth potentials. It was also true for rock bass although much of it was due to the wide spawning window that this species Utilized. This may have masked any genetic growth differences that occured. Field and laboratory studies have demonstrated that the Probability of survival for northern populations of B“"elleouth bass depends closely on the size attained before the first winter because winter mortality is significantly related to size (Oliver et al. 1979; Shuter et al. 1980; wales 1981; Shuter et al. 1985). Size distributions in years of poor growth show a strong positive skew, fish less than 6.0 centimeters total length rarely survive the winter (Shuter et al. 1985). Most of the smallmouth bass DD33!..1lation in the Red Cedar River in 1984 was smaller than 6‘ Q centimeters. Oliver et al. (1979) indicated that there vgr‘e lower levels of dry weight/wet weight and ignitable 'Qt/dry weight in dying fish than in living fish, tending to support the hypothesis that death is a result of exhaustion () Ill 3" 83 of energy substrates. The data analysis of these studies supported that large smallmouth bass survive their first winter better than smaller ones. This component should be further studied for YOY rock bass and smallmouth bass in the Red Cedar River. This study did clearly show the importance of vegetative habitat for YOY fish. Large woody snags and root wade were also important for adult rock bass and smallmouth base as was ascertained by electrofishing. We should be concerned by the loss of this habitat. Vegetation beds and their associated food supplies are decreasing, partially due to natural cyclic processes and partially due to man-made impacts such as channelization which tends to destabilize Stream systems during flooding. Large woody habitat is also being lost due to user preference conflicts. Often log jams are chain sawed to facilitate canoeing which destabilizes the fish structure during flood conditions. It is these Struotural components of the stream environment that we must pro‘tect and enhance if we are to establish a quality recreational fishery. Perry (1974) and Edwards (1977) found mitigation structures improved the bass population and sport fiehery considerably on channelized portions of the D‘Lehtangy River, Ohio. With increased stream habitat marlegement the Red Cedar River could provide an excellent SIDQrt fishery. 84 W The results of this thesis primarily support the importance of vegetative structure as cover for YOY fish in warmwater lotic systems. YOY rock bass and smallmouth bass were found to primarily utilize submergent macrophytes during the day. Data analysis suggested that there was a weak degree of disassociation between the two species in this vegetation type. YOY rock bass do not exhibit habitat partitioning by size between the emergent and submergent macrophyte beds. Rock bass fed at night while smallmouth bass fed primarily at sunrise and prior to sunset with some feeding occurring during the day. Smallmouth bass and largemouth base were found to contain YOY rock bass in their stomachs during the day. 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APPENDIX A 94 Table A1: Mean daily discharge, in cubic feet per second, for the water year October 1982 to September 1983 in the Red Cedar River at the USGS gaging station near Williamston, MI 10 22 41 99 73 55 255 320 348 172 42 19 11 11 22 48 84 84 44 237 328 311 142 39 31 11 12 22 69 74 86 47 209 316 273 112 37 31 11 13 21 78 60 78 50 167 301 236 90 34 26 10 14 21 71 63 76 50 135 367 196 79 33 23 10 15 20 62 64 71 56 120 451 156 71 32 22 9.1 16 19 54 85 42 61 108 430 130 66 32 21 13 17 19 48 93 57 84 100 422 115 60 31 20 16 18 19 45 93 47 93 101 406 104 56 29 20 16 19 20 42 90 45 93 121 379 103 52 31 19 38 20 2O 70 98 40 112 143 364 159 48 34 17 27 21 21 103 103 38 124 136 353 197 47 31 14 31 22 22 104 97 38 129 116 337 215 45 29 16 29 23 22 97 97 43 154 126 322 258 41 28 17 25 24 20 105 137 47 170 133 299 275 40 27 16 22 25 20 101 205 49 156 125 270 278 39 25 15 19 26 20 90 255 45 118 118 237 268 35 24 13 18 27 21 79 234 43 106 131 201 242 43 22 15 18 28 21 73 224 41 97 278 174 212 139 22 14 17 29 19 88 227 45 --- 379 205 182 237 25 12 17 30 20 103 190 73 --- 379 222 159 234 28 15 16 31 20 --- 143 89 --- 372 --- 147 --- 30 17 ---- MEAN 21.4 65.8 129 64.9 98.7 164 321 268 115 49.8 21.0 17.0 MAN 29 105 255 116 186 379 451 498 237 221 34 38 MIN 19 25 60 38 44 89 174 103 35 22 12 9.1 DRAINAGE AREA-163 SQUARE MILES 95 Table A2: lean daily diecharge. in cubic feet per eecond, for the water year October 1982 to Septeaber 1983 in the Red Cedar River at the USGS gaging etation near Eaet Lancing. RI AY OCT NOV DEC JAN FEB HAR APR MAY JUN JUL AUG SEP 1 62 57 236 279 205 208 760 540 339 462 55 38 2 55 92 219 247 198 202 705 980 311 411 57 36 3 51 170 264 222 403 194 820 1260 295 311 53 34 4 49 177 363 170 431 194 880 1190 387 219 49 31 5 42 135 399 180 283 198 790 1010 453 177 47 29 6 42 114 435 170 226 208 665 850 431 146 47 51 7 40 97 387 166 202 244 640 740 427 120 44 36 8 38 84 319 163 163 560 660 890 403 105 42 36 9 38 79 264 152 146 725 650 925 359 97 38 32 10 40 84 226 156 120 655 860 810 315 89 44 31 11 40 97 198 177 95 530 895 650 279 84 72 28 12 40 138 160 194 102 435 795 540 240 77 62 26 13 40 194 132 177 108 375 690 458 198 72 55 26 14 40 188 146 163 108 323 850 407 170 65 49 26 15 40 160 138 156 126 283 1080 367 160 65 42 26 16 40 138 174 89 146 250 1050 323 146 62 42 38 17 40 123 205 126 205 230 905 291 126 72 44 34 18 40 111 198 102 240 230 805 268 114 65 40 42 19 38 100 194 100 233 283 745 272 105 60 40 120 20 42 132 205 89 250 347 695 335 97 60 36 89 21 40 233 219 84 279 331 665 415 89 69 44 79 22 40 258 212 84 291 303 630 458 87 65 47 72 23 40 247 205 89 339 287 565 620 84 57 36 65' 24 40 261 315 100 387 291 510 625 74 55 34 55 25 41 244 510 105 351 287 458 560 69 53 34 49 26 38 212 610 100 287 272 415 525 67 49 32 44 27 38 184 545 92‘ 240 319 375 471 123 44 29 42 28 38 170 490 89 219 715 387 427 605 44 28 40 29A 38 202 520 92 --- 940 458 403 740 51 29 38 30 38 244 431 126 --- 960 476 383 550 55 42 36 31 38 --- 343 230 --- 855 --- 355 --- 53 42 --- HEAR 41. 5 158 299 144 228 395 696 592 261 110 43. 7 44. 3 ”AX 62 261 610 279 431 960 1080 1260 740 462 72 120 “IR 38 57 132 84 95 194 375 268 67 44 28 26 DRAINAGE AREA-355 SQUARE MILES 96 Table A3: Nean daily diecharge, in cubic feet per eecond, for the eater year October 1983 to Septeeber 1984 in the Red Cedar River at the USGS gaging etation near Eaet Lancing. NI Y OCT NOV DEC JAN FEB NAR APR HAY JUN JUL AUG SEP 10 38 55 149 92 89 102 307 166 120 34 38 21 11 36 62 156 89 126 89 268 163 108 65 31 28 12 38 62 268 84 323 79 247 160 95 49 26 24 13 62 62 466 84 645 87 254 177 87 44 23 38 14 74 60 476 84 905 92 268 194 79 36 21 34 15 72 62 431 82 720 102 343 198 77 34 20 49 16 60 87 375 79 555 323 411 188 72 31 18 38 17 53 114 315 79 495 530 471 174 67 28 18 34 18 51 117 219 79 480 431 610 166 65 26 20 29 19 47 111 142 79 462 347 645 163 62 26 18 28 2O 44 120 163 84 431 323 585 166 60 26 16 26 21 44 129 180 87 383 525 515 174 57 24 15 26 22 51 126 152 92 335 705 458 214 53 24 15 24 23 60 177 135 87 295 660 466 331 51 24 14 23 24 65 244 126 77 268 565 520 435 49 23 14 23 25 62 226 114 69 240 610 540 448 49 24 14 36 26 57 191 100 72 216 730 505 640 44 24 12 40 27 55 163 97 77 194 730 453 715 42 26 13 49 28 51 208 97 77 174 650 411 680 40 26 14 51 29 49 268 100 77 123 570 363 695 38 28 14 47 30 47 247 97 77 --- 510 327 700 34 28 15 42 31 44 --- 95 74 --- 444 --- 635 --- 24 15 --- NEAN 47.4 114 187 86.1 285 331 404 306 129 31.4 23.6 29.0 NAN 74 268 476 105 905 730 645 715 540 65 91 51 NIN 32 47 95 69 74 79 247 160 34 23 12 16 DRAINAGE AREA-355 SQUARE NILES NOTEsPROVISIONAL DATA 97 Table A4: Hean daily diecharge, the eater year October 1983 to September 1984 in the in cubic feet per eecond. for Red Cedar River at the USGS gaging etation near Uilliaaeton, HI DAY OCT NOV 1 16 30 2 16 35 3 16 45 4 16 45 5 17 41 6 17 38 7 17 36 8 18 35 9 2O 35 1O 19 34 11 20 35 12 19 37 13 28 37 14 35 35 15 33 37 16 29 58 17 27 74 18 25 71 19 24 66 20 23 72 21 23 78 22 23 73 23 33 79 24 35 108 25 35 108 26 33 97 27 33 85 28 32 101 29 30 127 30 30 121 31 30 --- NEAN 24.9 62.4 NAN 35 127 NIN 16 3O 45 45 94.0 233 45 JUL AUG SEP 23 10 7.6 21 11 7.9 21 11 7.7 21 14 8.1 20 14 7.3 21 13 8.8 21 12 8.6 19 12 7.9 19 14 8.0 20 16 10 29 14 12 28 12 13 25 11 14 22 10 21 20 7.9 21 19 8.2 18 18 7.1 15 17 7.7 14 16 7.7 13 15 6.5 12 15 6.8 12 15 5.8 11 13 6.2 11 15 5.3 12 14 6.0 15 13 5.9 22 14 5.1 27 14 6.1 28 12 5.9 24 10 7.5 21 11 7.8 ---- 18.1 9.27 13.9 29 16 28 1O 5. 1 7. 3 DRAINAGE AREA-163 SQUARE NILES NOTEsPROVISIONAL DATA 98 Table A5: Bailey population estimates of the numbers of rock bass in each age class at the Vanatta site (404meters) in 1983 and 1984 based on October mark-recapture electrofishing data AG 1983 POPULATION 1984 POPULATION ESTIMATE ESTIMATE l 23 267 2 10 96 3 46 13 4 76 7 5 48 reproductive 10 adults 6 44 17 7 2 l 8 5 2 'Total # of adults 221 50 99 Table A6: End of the year numbers of young-of-the-year fish per meter squared of emergent vegetation captured by seining at Sherwood study site and the mean total length of fish captured in zone II by elec- trofishing in 1985 SEINING-Shervood NOVEMBER 1985 Rock Bass Smallmouth #lmeter squared .067 0 mean size(mm) 36.69 --- sd 1.95 --- N 7 O ELECTROFISHING-Vanatta and Dobie Roads. NOVEMBER 1985 Rock Bass Smallmouth #Imeter squared --- --- mean size(mm) 37.67 78.50 sd 1.53 6.61 HICHIGQN STRTE UNIV. LIBRRRIES 1|HIHWIWWHIWINll”|W|H|||1|NHIIIHWIIHHHI 31293000736581