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CHARACTERISTICS OF FISH POPULATIONS IN UPPER MISSISSIPPI RIVER BACKWATER AREAS

Manne Bio^oeioal Laboreiory

LIBRARY

SEP 2 01965

WOODS HOLE, MASS.

UNITED STATES DEPARTMENT OF THE INTERIOR

FISH AND WILDLIFE SERVICE BUREAU OF SPORT FISHERIES AND WILDLIFE

Circular 212

The United States Department of the Interior, created in 1849, is concerned with management, conservation, and de- velopment of the Nation's water, wildlife, fish, mineral, forest, and park and recreational resources. It has major responsibilities also for Indian and Territorial affairs.

As America's principal conservation agency, the Department works to assure that nonrenewable resources are developed and used wisely, that park and recreational resources are conserved for the future, and that renewable resources make their full contribution to the progress, prosperity, and security of the United States, now and in the future.

UNITED STATES DEPARTMENT OF THE INTEJIIOR, STEWART L, UDALL, SECRETARY Stanly A. Cain, Assistant Secretary for Fish and Wildlife Fish and Wildlife Service, Clarence F. Pautzke, Commissioner Bureau of Sport Fisheries and Wildlife, John S. Gottschalk, Director

CHARACTERISTICS OF FISH POPULATIONS IN UPPER MISSISSIPPI RIVER BACKWATER AREAS

By

Lyle M. Christenson, Chief Fishery Biologist Wisconsin Conservation Department, Research and Planning Division

Madison, Wisconsin

and

Lloyd L. Smith, Department of Entomology, Fisheries, and Wildlife University of Minnesota, St. Paul, Minnesota

Circular 212 Washington, D. C. • March 1965

CONTENTS

Rge

Introduction 1

Description of backwater areas 2

Miller Lake 2

Areas A and B 2

Methods and materials 5

Toxicant application 5

Fish collection 5

Weight and species composition of the fish populations 6

Reliability of estimates 6

Standing crops 9

Miller Lake , • • ■ 9

Area A 16

Area B 16

Fluctuations in standing crops of area B 16

Ifercentage composition 16

Weight per acre 16

Comparison with other waters 20

Mississippi River backwaters 20

Inland waters of adjacent States 20

Size and age-group composition of population in area B, 1948-1949 21

Size and age structure 21

Predators 21

Bowfins 21

Shortnose gar 21

Longnose gar 21

Game fish 21

Largemouth bass 21

Northern pike 21

Sauger 26

Walleye 26

Panfish 26

Bluegill 26

Black crappie 26

White crappie 27

White bass 27

Yellow perch 28

Catfish 28

Channel catfish 28

Flathead catfish 28

Black bullhead 30

Forage fish 30

Gizzard shad 30

Rough fish 30

Carp 30

Spotted sucker 30

Freshwater drum 30

Northern river carpsucker 30

iii

CONTENTS (continued)

Page

Northern redhorse 30

Bigmouth buffalo 30

Smallmouth buffalo 30

Comparison with other Mississippi River areas 30

.i. argemouth bass 34

Bluegill 34

Black crappie 34

White crappie 34

General consideration of age structure 34

Growth rates of fish 34

Miller Lake 35

Areas A and B 35

Bluegill 36

Black crappie 36

White crappie 38

Largemouth basii 38

Sauger 38

Carp 38

Spotted sucker 38

Freshwater drum 39

White bass 39

Yellow perch 39

Bigmouth buffalo 40

Smallmouth buffalo 40

Orangespotted sunfish 40

Comparison of growth in areas A and B and Illinois waters of the

Mississippi River 40

General consideration of growth 41

Factors influencing productivity and population development 41

Water and soil fertility 42

Water fertility 42

Bottom soils 42

Food availability 42

Species composition 45

Water-level fluctuation 45

Summary and conclusions 46

Acknowledgments 49

References 50

CHARACTERISTICS OF FISH POPULATIONS IN UPPER MISSISSIPPI RIVER BACKWATER AREAS

By

Lyle M. Christenson

and

Lloyd L . Smith

ABSTRACT

Standing crops of fish and their fluctuations from year to year, age and size class structure of the populations, and growth rates of the com- mon species present in three backwater areas of the upper Mississippi River were determined during the period 1947-52 under the auspices of the Upper Mississippi River Conservation Committee.

Standing crops as estimated from six collections following rotenone treatment of blocked-off areas ranged from 39 to 605 and averaged 248 pounds per acre.

Weight composition by species groups varied greatly among four col- lections mad» in one study area but was characterized by the following percentages: (1) Rough fish - 38 (2) Non-game predaceous species - 27 (3) Panfish - 13 (4) Game fish - 12 (5) Catfish - 11, and (6) Forage fish - 1. Among the same four collections, the average composition in pounds per acre was: (1) Rou^ fish - 112 (2) Non-game predaceous species 77 (3) Panfish - io C4) Game fish - 29 (5) Catfish - 30, and (6) Forage fish - 2.

Very few fish over 5 years of age were found and most of the game fish and panfish were less than 3 years old.

Growth rates of most species were greater than most of those described in other waters of the north central States and in downstream areas of the Mississippi River.

Limited data on environmental factors are presented. Differences in standing crop and species composition could not be related to changes in the water level.

INTRODUCTION

Numerous attempts to remove fish popu- lations in order 'o determine the productivity ind population structure of various landlocked waters have been made, but most were con- ducted v/here populations were abnormal and consequently the findings were not typical of normal conditions (Solman, 50i.'). Many of them were only partially successfjl because recoveries of fish were incomplete . Until the

research program of the Tennessee Valley Authority was initiated, little attention had been given to detailed studies of warm -water fish populations of backwater areas in rivers and impoundments . Surber (52, 5^ studied the fish populations in some upper Mississippi River sloughs before installation of navigation dams; many of the conditions lie described stil) exist. Meehean (32) attempted to show the

L'' Undeiscored figures in parentheses refer to list of references beginning on page 50.

relation of scale structure to the life history of the bluegill in some upper Mississippi River sloughs. Tarzwell (57, 58) and Eschmeyer (19), employing a technique similar to that used in these studies, obtained information on fish popu- lations in restricted areas of TVA reservoirs.

The studies discussed here were initiated primarily to evaluate the standing fish popu- lations of representative backwater areas created by the navigation dams on the upper Mississippi River. At normal pool levels these areas are connected with the main and side channels and form an important part of the total fish-producing waters.

Collection of data on fish populations in the backwaters has been an integral part of a broad fishery investigation carried on by the Upper Mississippi River Conservation Com- mitteer' since its beginning. Under auspices of this organization the populations of seven backwater areas in the upper river were studied. The present discussion is limited to three areas in the Minnesota -Wisconsin section of the river: Miller Lake, area A, and area B. Collections were made by means of toxicants in Miller Lake in August 1957, in area A in July 1948, and in area B in July 1948 , August 1949 and 1951 , and September 1952. The objectives of the study were to determine (1) fish productivity, (2) fluctuations in the populations from year to year, (3) population structure, (4) rate of growth of the common species present, and (5) effects of navigation -pool drawdowns on the fish populations of these backwater areas.

Description of the backwater areas

Miller Lake: --Miller Lake.

3/

a backwater

area in pool 8 of the upper Mississippi River lock and dam system, is located approximately 2 miles below the interstate bridge at La Crosse, Wisconsin, on the Wisconsin side of the river (fig. 1). On August 15, 1947, the date offish collection, it covered an area of il.9 acresl' . The water level at the pool -control point ap- proximately 1 mile below La Crosse was 630.97 feet (elevation above mean sea level). The normal level at this gauge is 631 .00 feet.

Two outlets connect the lake indirectly with the main channel. One, appriximately 70 feet wide and 5 feet deep, empties into a large running s'.jgh. The other, approximately 15 feet wide, drains into a shallow ditch that has no appreciable current at normal pool le' el . There is a single inlet less than 3 feet in maxi- mui.i width which is very shallow and choked with weeds . The amount of water entering the backwater from this source is negligible. Silt deposited periodically during high water stages forms the bottom.

A heavy growth of coontail, Ceratophyllum demersum , was on the periphery of the lake and in the bays at the time of poisoning. The water temperature 1 foot below the surface was 80° F. and the turbidity was 320 ppm as measured with a U.S. Geological Survey standard platinum needle scale.

Areas A and B:- -Areas A and B lie west of Fountain City, Wisconsin, in pool number 5 -A (fig. 2). The main channel of the river

2/ The Upper Mississippi River Conservation Committee was organized in 19lt3. It is composed ~ of representatives from Minnesota, Wisconsin, Iowa, Illinois, Missouri, the U.S. Fish and Wildlife Service, and the U.S. Corps of Engineers. The primary purpose of the Committee is to conduct biological and economic studies concerning fish and wildlife of the upper Mississippi River.

3/ Descriptive information and raw data pertaining to Miller Lake are from a preliminary "" report (unpublished) prepared by D.W. Kelley and John Greenbank, parts of which appeared

in the Fourth Progress Report of the Technical Committee for Fisheries of the Upper

Mississippi River Conservation Committee, January 27, 19U8.

h/ Original determinations of areas of Miller Lake, area A and area B, and of area B in ~ 1951 were made from plane-table maps. Acreages of area B for the years 19h9 and 1952 are estimates based on the original maps.

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Figure 1: — I-lississippi River approximately 2 miles south of La Crosse. VJi scons in, Miller Lake is indicated by a line near the center of the photograph (aerial photo taken J'lly 28, 19L7).

follows the east bank of the valley proper at this location. West of the main channel the broad river bottoms are dissected by lesser meandering channels and it is in this region that the two sampling areas are located. Nor- mal level of the pool at the U.S. Corps of Engineers Fountain City boatyard gauge is 650.50 feet.

Area A covered 1.35 acres on July 6, 1948. It had a maximum depth of 4.5 feet and an aver- age depth of 2.4 feet with a water level of 650.61 feet at the Fountain City gauge. The bottom was silt and except for a heavy stand of Sagittaria sp. at the closed end of the backwater, aquatic vege- tation was sparse.

Area B covered 3.36 acres on July 7, 1948 (fig. 3) . It had a maximum depth of 9 feet and an average depth of 5 .5 feet when the water level at the Fountain City gauge was 650.65. The silt bottom supported a more diversified and abundant stand of aquatic vegetation than was found in area A. Sagittaria sp. predominated, Potamogeton natans was abundant, and there was a scattering of Valliancria sp. and Nymphaea tuberosa .

Water temperature and turbidity were not determined in areas A and B on these dates but maximum air temperature at Winona, Minnesota, 6 miles downstream, on both dates was 96-F. The water in both cases was clear enough to permit the bottom to be seen to depths of approximately 3 feet.

Figure 2: --Mississippi River in vicinity of Fountain City, Wisconsin. Areas A and B are indicated by Tetters. Direction of river flow in this photograph is from bottom to top (aerial photograph taken July 31, 195l).

Figure 3: — Outline map of area B in 19h8. The shaded area indicates the extent of sand deposition noted in 1951 •

On August 3, 1949, the water level at the gauge stood at 649 .65 , 1 .00 feet lower than on the date of the previous operation. This change i-educed the size of area B to approximately 3 acres, the maximum depth to 8.0 feet, and the average depth to 4 .0 feet . Neither water temp- erature nor turbidity was determinsd. The vvater was clear enough to permit the bottom to be seen over a major portion of the area .

On August 14, 1951 , the water level stood at 650.18, 0.53 feet above that of August 3 , 1949 , and 0 .47 feet below that of July 7 , 1948 . Deposition of sand had filled one small bay and, together with the lower water level, had re- duced the area to 3.1 acres. The maximum depth was 7.5 feet and the average depth approximated 4 feet. Surface water temp- erature at noon was 73° F . and the silt bottom was visible to a depth of approximately 2 feet. Aquatic vegetation, identified by John Moyle of the Minnesota Department of Conservation was much more abundant than in July, 1948. The following species were present: mud plantain (Heteranthera dubia), coontail (Ceratophyllum demersum), western waterweed (Anacharis occidentalis), arrowhead (Sagittaria sp.), sago pondweed (Potamogeton pectinatus), duckweeds (Lemna minor, Spirodela polyrhiza), wild celery (Vallisneria americana), white waterlily (Nymphaea tuberosa), and river pondweed (Potamogeton nodosus). Coontail was the most abundant species, followed by western water- weed and mud plantain. Arrowhead was abun- dant only at the closed end of the area.

On September 17, 1952, the water level was 649.90 feet, 0.28 feet below that of August 14, 1951, 0.25 feet above that of August 3, 1949, and 0.75 feet below that of July 7, 1948. On the basis of previous plane tabje computations , the size of area B was estimated to be approxi- mately 3.0 acres. The maximum and average depths were 7 .5 and approximately 4 feet , re- spectively. Surface-water temperature at noon was 66° F. Bottom, turbidity, and vegetation were similar to those existing on the date of the preceding operation, August 14, 1951.

METHODS AND MATERIALS

Toxicant application

The methods of applying the fish toxicant followed in each of the six operations were nearly identical. A 0.75 -inch (stretch measure) mesh seine was installed across the open end of each area and the toxicant was then distrib- uted. The seine was laid out early in the morning in 1948 and 1949, in mid-afternoon on the day prior to poisoning in 1951 , and at noon in 1952. The corresponding time for the Miller Lake operation in 1947 is unknown. Diluted toxicant was poured over the side of moving boats pow- ered by outboard motors. During application the areas were repeatedly traversed. Dis- persion of the poison in weedbeds and shallow portions was accomplished with hand scoops or portable hand-operated pumps. Fbwdered derris root warranted 5 percent rotenone (4.5 percent in Miller Lake) was used in the first four op- erations and emulsified rotenone was applied to area B in 1951 and 1952. The concentration of toxicant in all cases was 0.50-0.75 ppm.

Fish collection

During the 3 days following application of the toxicant in areas A and B, as many fish as possible were picked up and the small numbers of those remaining were estimated. In Miller Lake an attempt was made to collect all fish except forage species, some young -of -the -year largemouth bass, some yellow perch, and lesser sunfishes and bluegills, under 3.5 inches in length. The estimated members of observed unrecovered fish, primarily of age group 0, in all operations except area B, 1952, were assigned a total weight on the basis of those actually recovered an' weighed. In area B the 1952 collection of forage fish and young-of-the- year specimens was considered to be of little utility because a large quantity of small fish was taken by gulls and terns .

In all operations total length of fish (length from anterior tip of snout to the extreme end of the caudal fin with the lobes compressed) was recorded to the nearest 0.1 inch and weight to the nearest 0.05 pound. General scale samples were taken from areas of the bodies of the vnrious species in accordance with Smith (48). Only length and weight determinations were made of the bowfin, northern longnose gar, shortnose gar, channel catfish, flathead catfish, bullheads, and paddlefish.

Up to 100 scale samples per species were taken in Miller Lake. Additional length meas- urements, up to approximately 500 for one species, were recorded for the most abundantly represented species . The remaining fish were counted and weighed in bulk . Total number and total weight of all forage fish were estimated. Total lengths and weights were recorded for all fish from area A and from area B in 1948, 1951 , and 1952 except young-of-the-year specimens and forage fish for which only numbers and bulk weight were noted. Up to 50 scale samples were collected from each species of imfXDrtance except as indicated above. In area B, during the 1949 operation, 50 scale samples were taken from most species and an additional 50 length measurements were made if enough fish were available. The remaining fish were counted and weighed collectively by species .

In addition to the fish collected, the numbers of unrecovered small specimens of some species were estimated and assigned a total weight on the basis of recovered samples in the respective size classes.

WEIGHT AND SPECIES COMPOSITION OF THE FISH POPULATIONS

In an analysis of a fishery the determi- nation of the capability of a water to produce fish is of primary importance. The term "fish production" has been employed in the literature to convey two different meanings: 1) the sur- plus of fish available for harvest in any period, and 2) the total fish population present at any one time. In this study the term is used in the latter sense only. Fish production, or standing crop, is considered here in terms of pounds of fish per acre with discussions of size and age -group comjHDSition presented in a later section. The list of fish species in table 1 is complete for the 1948 and 1949 collections in area B but omits the "forage fish" group in the other studies .

The broad nature of the present studies suggested the grouping of all species under six classifications (predators, game fish, panfish, catfish, rough fish, and forage fish) following the precedent established by the Technical Committee for Fisheries of the Upper Missis-

sippi River Conservation Committee in its pre- liminary reports on other backwater populations (Uppsr Mississippi River Conservation Com- mittee, 63, 64). Bamickol and Starrett(3) em- ployed grouping of a similar type but pointed out certain inadequacies of the arrangement.

Reliability of estimates

Consideration was given to the efficiency of the toxicant application and fish collection in area B during 1951 . Sixteen fin-clipped fish with a minimum length of approximately 6 inches and representing eight species were released prior to application of the toxicant . In addition, one spotted sucker was placed in a wire cage and lowered :o the bottom at the deepest point in the area. A 0.25 -inch -mesh seine 8 feet wide and 35 feet long was weighted on both the lead and float lines and laid flat on the bottom in the deepest water. On the day following the poisoning a 250-foot experimental gill net and a 1-inch bar mesh frame net with a 50-foot lead were set in the enclosed area .

The condition of the spotted sucker in the cage 3 hours after application of the poison had been completed indicated that death had occurred soon after the toxicant was placed in the water. All of the 16 marked fish were recovered and neither the gill net nor the frame net caught any fish. Only two trout-perch and two small gizzard shad were found in the seine which had been spread on the bottom. Minnows and young-of- the=year crappies placed in a wire cage 56 hours after application of the toxicant showed immediate signs of distress and most of them died within 15 minutes. While individual checks on the efficiency of the toxicant application and fish collection were not conclusive because their scope was limited, as a group they indicated a complete kill and a recovery of fish approaching 100 percent by weight. Although no checks of this nature were made in the other studies, the procedures were similar and therefore it is probable that comparable efficiency was attained except in Miller Lake.

At Miller Lake the poisoning was preceded by netting, seining, and fin-clipping operations to check the relative efficiency of nets used in test netting operations. These activities were

Table 1: — Pish species taken from Miller Lake (19U7), Area A '~ " , and Area 2 (19U8, 19li9 , 1951, and 1952).

Miller Area Area

Species ^"^® ^- 19U8 19U9 1951 1952

PREDATORS

aiortnose gar — Lepisosteus plato-

stomus Rafinesque X X X

North a*n longnose gar — Lepisosteus

osseus ojcynnis Rafinesque X X X X X

Bowfin — Amia calva Linnaeus X X X X X X

QAME FISH

Northern pike — Esox lucius Lin- naeus X X X X X X

Northern largemouth bass — Micro p-

terus salmoides salmnides

(Lacepede)

Sanger — Stizostedion canadense

(Smith)

Walleye — Stizostedion vitreum

vitreum (Mitchill)

PANHSH

White bass — Morone chrysops

(Rafinesque)

Green sunf ish — Lepomis cyanellus

Raifinesque

Pumpkins eed — Lepomis gibbosus

(Linnaeus)

Northern bluegill — Lepomis macro -

chirus macrochirus Rafinesque ... Orangespotted sunfish — Lepomis

humilis (Girard)

Northern rock bass — Ambloplites

rupestris rupestris (Rafinesque) . . White crappie — Pomoxis annularis

Rafinesque

Black crappie — Pomoxis nigro-

maculat\:i3 (LeSueur) 7

Yellow perch ~ Perca flavescens

(Mitchill)

X	X	X	X	X	X
X	X	X	X	X	X
X		X	X	X	X

	X	X	X		X
			X	X	X
X		X	X	X	X
X	X	X	X	X	X
X	X	X X	X	X X	X
X	X	X	X	X	X
X	X	X	X	X	X
X		X	X	X	X

Table 1 (continued)

Miller Area Area

SP^^^*^ Lake A ^^^q ^^^^ -^^^^ ^^^^

CATFISH

Channel catfish — Ictalurus

lacustris lac'Jistris (Walbaum) ... X X X X X X

Northern brown bullhead — Ameiurus

nebulosus nebulosus (LeSueur) ... X Northern black bullhead — Ameiurus

aelas melas (Rafinesque) X X X X X

Yellow bullhead — Ameiurus natal 1 s

(LeSuetir) X

Flathead catfish — Pilodictis

olivaris (Rafinesque) X X

BDUGH FISH

Paddle fish — Polyodon spathula

(Walbaum) X

Mooneye — Hiodon tergisus LeSueur . X

Bigmouth buffalo — Ictiobus

cyprinellus (Valenciennes) X X X

Smallmouth buffalo — Ictiobus

bubalus (Rafinesque) X I

Northern river carpsucker — Carpi- odes carpio carpio (Rafinesque) . XX IX

Northern redhorse — Moxostoma

aureclum (LeSueur) X X X X

Spotted sucker — Minytrema laelanops

(Rafinesque) X X X X X

Carp — Cyprinus carpio Linnaeus ... X X X X X X

Freshwater drum — Aplodinotus

grunniens Rafinesque X X X X X

FORAGE FISH

Cyprinidao

Western golden shiner ~ Notemi-

gonus crysoleucas auratus

(Rafinesque) X X X X X

Pugnose minnow — Opsopoeodus

eniliae R<y X X

Lake Snerald shiner — Notropis ,

atherinoides acut'us ( Laphamyi/ X

Northern weed shiner - Notropis

roseus richardsonl Hubbs and

Greene •• X X

1/ Not listed by Bailey (19$1).

Table 1 (concluded)

Miller Species Lake

JDBAGE FISH (contiimed)

Cyprinidae

Spottall shiner — Notropls

hnrlsoci-as (Clinton)

Spotfir. stiiner — Kotropla

s-pilopxams (Cope)

Mortbem sisic shiner — Notropia •yplacellus Tolncellaa (Cope) . Bullhead ainnow — Piaephales

perspicnus (Girard)

Eluntaose KLnnow — Figephales

notataa ( Raf inescue )

Hortbem fathead nicnow —

Piaephales proaelas proaelas

Eaflnesqae

Gl»»ard shad — Do ro soma eepediannw

(LeSueur) X

Tadpole nadtoa — Schi Ibeodes aollis

(Heraann) I

Trout-perch — Percopsis osisco-

Maycna (Valbaioi)

Western pirate-perch — Aphredoderas

sayanus eibbo y-LS LeSaeur • .

Northern brook silTersides — Labidesthes sic cuius sicculns

(Cope)

Northern logperch — Percina

caprodea segifasciata (D^ay) ... Central Johnny darter — Etheostoma

nigma cignua P.aflnesqae •

Mud darter — Stheostcaia asprigenis

(?orbes)

Iowa darter — Btheostom eiile

(uirard)

Area Area

:-. 151:5 19;^ 1951 1952

conducted within a 10-day jjeriod prior to in- stallation of the block seine. Only 15 .9 percent of the marked fish were recovered following application of the toxicant on August 16 . Known netting mortality partially accounted for the low recovery of fin-clipped fish but in view of the evidence presented above for area B in 1951, it is likely that the activity preceding installation of the block seine was responsible for the egress of many fish . Since the value of these data is directly related to the extent of fish recovery, the use of the Miller Lake material here is limited.

	I	I
	I	I X X
	X
I	I
I	X	I	X	X
I	I	I	X	X
	X		X X	I
	I	I
I	I	I
	X	X	X
I	I	X X
Standing	crops

Miller Lake; --At the time of collection the fish population of Miller Lake, exclusive of forage fish, was compwsed of 17 species (Table 1). Only three species in the forage- fish group were identified although others were present. On the basis of both recovered^.' and estimated numbers and weights. Miller Lake produced 3,798 fish and 153.8 pounds per acre (Table 2) .

5/ The words "recover", "collect", etc. refer to the total of fish actuallv

ar.c their derivatives as subssquer.tl^ recovered and estir.ated.

srTDloved

Table 2 :-- Standing crop of fLsh in Miller Lake, August 15, 1957, expressed as number pounds per acre of various species.

and

Species

Number	Wei^t
Number per acre	Percentage of total number	Pounds Percentage per of total acre wei^t
6.1	0.2	9.5 6.2
6.1 19U.6 26.3 1.6 I.I4	0.2 5.1 0.7	9.5 6.^ 9.9 6.1i 16.9 11.0 O.U 0.3 O.U 0.2
223.9 0.1 1,216.1 U0.8 3.8 I468.3 U2.0	5.9 32.0 1.1 0.1 12.3 1.1	27.6 17.9 63.8 Ul.5 U.l 2.7 0.8 0.5 6.6 U.3 1.7 1.1
1,771.2 5.8 U.U 0.5	U6.6 0.2 0.1	77.0 50.1 2.8 1.8 2.0 1.3 1.2 0.8
10.7 1,260.5 188.0 336.1	0.3 33.2 I4.U 8.8	6.0 3.9 25.2 16.U 1.2 0.8 1.7 1.1
1,76U.7 0.1 0.2 21.li	I46.5 0.6	^8.1 18.3 0.1 0.1 5.5 3.6
21.7	0.6	5.6 3.7

Predators

Bowfin

Pane fiah

Largemouth bass

Northern pike

Sauger

Walleye

Panfish

White bass

Bluegill

Black crs^pie

White crappie

Yellow perch y.

Miscellaneous contrarchidsi/

Catfish

Northern brown bullhead

Yellow bullhead

Channel catfish

Forage fish

Gizzard shad

Minnows

Madtom

Rough fish

Smallmouth buffalo

Carp

Spotted sucker

GRAND TOTAL

3,798.3

153.8

1/ Includes orangespotted sunfish and pumpkinseed.

10

Table 3: -Standing crop of fish in area per acre of various species.

A, July 6, 19li8, expressed as number and poxmds

Number

Species

Predators

Bowf in

Northern longnose gar

Shortnose gar

Game fish

Largemouth bass

Northern pike

Sauger

Panfish

White bass

Bluegill

Black crappie

White crappie ^y.

Miscellaneous centrarchidsi/ .

Catfish

Northern black bullhead

Channel catfish

Forage fish

Gizzard shad

Minnows

Miscellaneous

Rough fish

Bigmouth buffalo

Carp

Northern river carpsucker ...

Northern redhorse

Freshwater drum

GRAND TOTAL

Number Percentage per of total acre number

Weight

Pounds Percentage per of total acre wei^t

3.0 0.7 23.7	0.2 1.5	12.1 0.1 h.9	30.8 O.U 12. u
27. U	1.7	17.1	U3.6
3.7	0.2	O.U	1.1
0.7 lo.a	0.6	0.7	1.9
114.8	O.B	1.1	3.0
77.0 9U.8 33.3 26.7 290.U	i4.8 5.9 2.1 1.6 18.0	0.1 2.1 2.8 Ij.O 0.9	O.U 5.3 7.1 10.2 2.3
522.2	32.3	9.9	25.3
0.7 2.2	0.1	h.l	12.0
2.9	0.1	1».7	12.0
182.2 I7O.I4 26.7	11.3 10,5 1.6	0.9 O.U	2.3 0.9
379.3	23.U	1.3	3.2
0.7 6U7.U 0.7 0.7 20.7	I4O.O 1.3	0.2 1.7 0.1 3.0	0.6 U.3 0.2 7.7
670.2	hl.^	^.0	12.tt

1,617.0

39.1

1/ Includes orangespotted sunfish and undetermined young-of-the-year Centrarchldae.

11

j^ swedes.

Joljr If IPiiBj expressed as nwber aid

Soeeie

.Ur.>r7

V— - - —	^^Tze^z^	ftju-ds	?erc en ta.ee
r or	:■: '.czsl	oer	Df total
icr=	T.—jz-er	acre	v«ie.-.t
£.3	0.2	33.1	15.2
0.9	—	0.3	0.1
5.S	- • 3	1.9	0.9
—^ • -	...	^;-J	-2.i
- -.:	a.3	0.8	o.U
-.:	0.1	a.8	10.0
9.2	:.3	1.6	0.7
2,"	Z .1	C.6	0.3

rT^r_a .

Ssi^er

Jtis

»■•■•*■■•■

itrapcELi

sid^.

_"2.0	13.3
151.1	5.6
636.9	13.7
6a. 9	1.9
95.5	2.8
_; . -	-• ^
:>-c.j	. t
0.3	—
13.7	O.k

1.3 h,0 li.O 6.2 0.3

13.3 2.9

0.6 1.8 1.8 2.8 0.2 0.2

3.ii 1.3

9.7

.f li''

!i51i.2

13.3

22.6

1.5 1.7

0.2

TT

0.7 0.7

0.1

1.5

'sic

Sortfcerr:

50C1" -

32^.i. 3.0 7.1

3,LlD.Ii

1.2 9.5

0.1 0.2

0.2

5.7

95.2

1.3

0.5

L.6

217.0

2.6

0.2 2.1

2.6

^37j

2/ Incl

-, -.r:r;t-percii, darters, sr;

^ siiTer=i36

12

Table 5: — Standing crop of fish in area per acre of various species.

August 3, 19h9, ejcpressed as number and pounds

Number

Weight

Soecies

Number	Percentage	Po'jnds	Percentage
tier	of total	per	of total
acre	n-omber	acre	weight
22.7	0.6	81^.3	13.9
8.0	0.2	6.I4	1.1
19.7	O.I4	26.7	Ij.lj
50.14	1.2	117. I4	19. li
292.7	7.2	9.2	1.5
6.0	0.1	13.3	2.2
6.3	0.2	1.7	0.3
3.7	0.1	6.1	1.0
306.7	7.6	30. 3	5.0
U.O	0.1	1.9	0.3
1,333.0	32.8	12.0	2.0
399.3	9.8	22.6	3.7
269.3	6.6	9.0	1.5
185.7	I4.6	0.9	0.1
175.7	14.3	0.3	___
2,367.0	5B.2	I46.5	7.6
1.0		0.3	M^M
13.3	0.3	37.7	6.3
U.3	0.3	38.0	6.3
336.3	8.3	156.8	25.9
796.0	19.6	l.C	0.2
67.2	1.5	0.1
1,195.0	29. a	157.9	26.1
6.3	0.2	7.9	1.3
2.7	0.1	2.L	O.U
69.7	1.7	165.0	27.3
0.3	—	0.8	0.1
8.7	0.2	9.5	1.6
37.7	0.9	29.2	1. 0
125. ij	3.1	2ll,.8	35.5

Predators

3owf in

Northern longnose gar

Shortnose gar

Game fish

Largemouth bass

Northern pike

Sauger

Walleye

Pan fish

'White bass

Bluegill

Black crappie

White crappie

Yellow perch

Miscellaneous centrarchidsi/ .

Catfish

Northern black bullhead

Channel catfish

Foraee fish

uizzard shad

Minnows .„

Miscellaneous^'

Rough fish

Bignouth buffalo

Smallnouth buffalo

Carp

Northern redhorse

Freshwater drum

Spotted sucker

GRAND TOTAL

14,060.7

6OI4.9

1/ Includes orangespotted sunfish, green sunfish, and pumpkinseed. 2/ Includes madtom, darters, and brook silversides.

13

Table 6: --Standing crop of fish in area B, August llj, 1951, expressed as number and pounds per acre of various species.

Species

Number

Number per acre

Percentage

of total

number

Pounds per acre

Weight

Percentage

of total

weight

Predators

Bowf in

Longnose gar

Game fish

Largemouth bass

Northern pike

Sauger

Walleye

Panfish

Bluegill

Black crappie

White crappie

Yellow perch

Miscellaneous centrarchidsi' .

Catfish

Northern black bullhead

Channel catfish

Forage fish

Qizzard shad

Minnows .«

Miscellaneous—'

Rough fish

Carp

Northern river carpsucker . . .

Northern redhorse

Freshwater drum

Spotted sucker

GRAND TOTAL

17.1 3»2

20.3

lU.O

21i.5

3.5

27.1

196.1

66.1 286.5 55.5 76.8 70.6

30.3 1,260.5

1.3

0.3

"ITF

11.2 1.9 0.3 2.1

5.2 22.7 \x.h 6.1 5.6

60.0	I4.8
32I4.2	25.7
63.5	5.0
i4l47.7	3^.^
0.3
3.5	0.3
0.3	—
1.3	0.1
2I4.8	2.0

XF

63.9 0.2

6IITI

9.7

2I4.IJ

0.6

3.6

383^

6.9

12.8

II4.0

1.3

0.9

0.7 0.6

0.1

TX

l.)4

3.6 0.9

1.5 36.1

I43.5 202. I4

31.6 0.1

31.7

I4.8

12.0

0.3

1.8

18.9

3.1) 6.3 7.0 0.6 0.I4

^%.<	I4I4.I	35.9	17.7
0.3 10.3	0.8	19.3	9.6
10.6	0.8	19.3	9.6

0.3 0.2

"oTT

0.7

1.8

O.I4

0.7

17.9

■2T:r

1/ Includes orangespotted sunfish, green sunfish, pumpkinseeds, and rock bass, 2/ Includes madtom, darters, trout-perch, pirateperch, and brook silversides.

14

Table ?:— Standing crop of fish in area B, Septer.iber 17, 1952, e>:nressed as pounds per acre of various species.

Pounds Df*r Percentage! of acre total weight

Predators

Bowfin 90.7 33.3

Northern lonsriose gar 0. J 0.1

91.0 33Tir

Game fish

Larg'=inouth bass 0.? 0,3

Northern Dike 1$.6 5*7

Sausier 2.2 0.8

Walieye ___ 5^]^ 2.0

2E7I~ 8TF"

P<tnfish

'<\Jhite bass 2.8 1.0

Blueeill 0.9 0.3

Black crappie 21.5 ?«9

White crappie 17.8 6,5

Yellow perch 0.5 0.2_

nirr' 13^9

Catfish

Northern black bullhead 0.1

Channel catfish 36.1 13.2

Flathead catfish 3.5 1.3

39.7 iluS'

F'orage fish

Gizzard shad 0.7 0.2

0.7 0.2

Rough fish

Carp 29.6 10.9

Northern river carpsucker 0.6 0.2

Freshwater drum 20.3 7.i4

Mooneye O.Ii 0.1

Paddlefish 5.1i 2.0

Spotted sucker 17.1 6.1i

73.7 27. n"

uFLAI^ID TOTAL 272.6

15

^sr 221.4 rr r>;»«.3 pci=io5 per

mr

irDC£_T 3ir.

3ar rw

-yar. ^zsje rsr- £3ir raner ~srr t-'i'ut=

1- ' •"— gp^-— »=^ Jiii.tr^ -=-=-=

rc<»r

iees sjTS- stswsc m :3Tor ce

- t ~—^::^

2^aa "w^^^ -^T-"

s _i

"TTTrm-g UrT £rr^ ir-^T± I_ .1 T'T'i - 221.4^ SZi

==— -sn, ^- perrs-]

oi-mnr is re.

K-HTZTSE"

I-lcaiit

3££ a: ~

■c^r .gT r— aaae. snf :

TE-ms^;, 3c poanis; rannss, :•! : .- - t'-T^

S3DZISC

5= ilSETflT

. by iSe "iaTgp-

r-jumsnanr tl ssnnnsr

I^a^i osia zssiiis ir £ irEal sc;

s 30IIIO5 aer £rr=.

£.^1= _ _=reti:: -~=CT3=~rtj.

rizn. -Tgr

-acaicrjrr =^

T — -

^TriIC£_=r

1=^- yirrpg 331S3. ^brio

-- i -^ — ^

.ai.r=£^

3C' J.' 32 5: I^ i

3i 3c U

jt

3C 5:

lec .iC "iae ~'=g''

Sc"* 3c^^^£^r^^c ~ '^ II _ " —

ii IPjt.

rse rr =r3:\:

ar-rc:^

100

90

80

70

z
o
t-	bO
01
o
Q.
s
o
<■)
	bO
UJ
o
<
H-
Z
LU
O
CE	40
UJ
a.

30

20 -

10 -

^

II I

UIKIlUUjj.

iiii^

1946 1949-A 1949-B I9SI 1952 AVERA6E-A AVERAGE-B

CALENDAR YEAR

IpREDATORS IIIgAME fish HpANFISH ^CATFISH HfORAGE FISH (IIIrOUGH FISH

Figure l:— Percentage composition by weight of the various species groups in the standing

crops of area B in 19h8, 19l;9, 19^1, and 1952. The 19h9-J^ and average-A columns include gizzard shad collected in 19h9. The 19h9-B and Average-B columns repre- sent the adjusted percentage composition when adult gizzard shad are excluded.

18

600

500 -

400

u a: o

<

ui

Q. 300

to a

z

3

o

CL

200

100

JPREDATORS

FxlGAME FISH

1949-B 1951 1952

CALENDAR YEAR

3p*nfish ^1 catfish

AVERA6E-A AVERAGE-B

■ FORAGE FISH

D

ROUGH FISH

Figure 5: -Standing crops of fish in area B in 19U8, 19^9, lo^l, and 1952 expressed as poimds per acre of the various species groups. The 19li9-A and Average-A columns include adult gizzard shad collected in 19h°. The 19h9-B and Average-B columns represent the adjusted standing crops when adult gizzard shad are excluded .

19

Table 9: — Standing crops cf species grc>ups fro3 ^.cr^r.em and southern sections of the -opper )*ississippi Hiver rackvaters expressed kS Bounds oer acre.

				Po-	inds oer	acre
• ater	Pred- ators	^■3ie fish	Pan- fish	Cat- fish	Forage A*SI1	fish	Tota3
ir=£ .--		17.1	1.1	9.9	-.•"		5.0	39.1
Area 3 l^		77.0	2S.0	36.0	30.0	I4I.O	112.0	32I4.O
MiUer Lake		9.5	27.6	77.0	6.0	26.1	5.6	153.8
Ogaaidca Ro.	1	5.1	2.7	10.5	59.6	81.2	210.5	390.62/
Oqaai^a No.	2	3.5	11.1	56.3	15. ij	!j03.1i	195.9	69ii.6
Savanna So.	1	17.7	2.2	21i.2	22.1	1.2	103.9	171. U
Saraona No.	2	16.7	U.l	Ul.h	26.9	12. I4	jOS.h	!422.8

1/ Average of 4 years; iig-ires are rcunded to nearest pouM. 2/ Indodee 20.7 pourtds per acre listed as ^fisceUaneoos".

Comparison witli other waters

Valid comparison of standing crops may be difficult for several reasons: there may be different methods of procuring population data, e.g. , poisoning and mark-recovery (Carlander, 12); there is a lack of estimates from repre- sentative waters (Solman, 50); the number of samples is insufficient; and some authors do not present data in a form from which com- parable elements may be extracted. Swingle and Smith (56) pointed out that the weight of fish which can be produced in a particular water varies with the species and therefore that when productivity is compared, the same species must be used to secure the most accurate results . This approach to comparison is employed here by species groups rather tban w^ith individual sp)ecies .

Mississippi River backwaters

Information on standing crops was ob- tained under the auspices of the Upper Mississippi River Conservation Committee from two backwater areas near Savanna, Illinois (Uppsr Mississippi River Conservation Committee (63) and two near Oquawka, Illinois (Upper Mississippi River Conservation Com- mittee, (64) (Table 9).

These estimates suggest that standing crops in the southern section are larger and have greater rough fish and smaller predator and game-fish components than those in the northern section of the upper river. \Miile the percentage of pan- fish was much lower in the southern backwaters, the actual mean standing crop of this group ap- proximated that of the area B average . As was the case in area B in 1949 , the gizzard shad strongly influenced the total productivity in the two Oquawka areas. Deletion of the contribution of this single species in all cases reduces the difference between the two sections in average standing crops of all other species combined. With this omission the average standing crops of the northern and southern sections were approximately 225 and 294 pounds per acre, respectively. The mean production of area B alone without adult gizzard shad would approxi- mate 285 pounds per acre, which would reduce the variation to insignificance.

Inland waters of adjacent States

Thompson (59) noted that, in contrast to the 500 pounds of fish per acre in most Illinois waters , the carrying capacity of northern Wis- consin and Michigan waters was about 50 pounds per acre or less, and that the intermediate regions with more fertile soUs than the northern

20

regions show intermediate poundages. This generalization is strengthened by the infor- mation presented in table 10, which tends to show that the average total standing crops are greater in more southerly regions . The major differences, however, are reflected primarily in the abundance of fish in the rough -fish group.

Game-fish production in area B exceeded that reported for northern Wisconsin, northern and southern Minnesota, and Iowa but was simi- lar to that shown for southern Wisconsin and Illinois . The average standing crop of panf ish in area B A-as similar to that found in northern waters, but less than that found in lakes further south.

The mean proauction of the combined panfish and game-fish groups was higher in area B than in lakes of the north and slightly greater than that reported for Iowa, central Illinois and Illinois River floodplain lakes . It was less than the average standing crops of those species in southern Minnesota, southern Wisconsin, and in three Illinois lakes.

SIZE AND AGE-GROUP COMPOSITION OF POPULATION IN AREA B, 1948-1949

specimens were recovered, of which 62 ranged from 17.0 to 24.9 inches in an uninterrupted 1-inch interval setpience. Forty of the latter group fell within the 21 .0- to 23.9-iQch interval. The 1948 sample did not indicate the presence of a strong size class which aiq)eared in the 1949 collection as a group of larger fish . The scarcity of fish under apiproxiraately 17 inches in both years and in 1951 and 1952, as well, suggests that yoimg and juveniles of this species do not generally inhabit backwater areas of this type in summer.

Shortnose gar; --Twenty-one specimens of shortnose gar under 8 .0 inches in length (pre- sumably of age group 0) and 12 between 15 .0 and 25 .9 inches were collected in 1948 . In 1949 only 2 fish of the former size were recovered hile 57 between 17 .0 and 25 .0 inches were collected .

Longnose gar;--T"-e :;-ree specimens collected in 1948 were :.:: ir .-.e 18.0-18.9-inch interval. Two size groups, 5.0-11.9 inches and 19.0-28.9 inches, were present in the 1949 collection of 34 fish .

Game fish

The total standing crop of a water area is an index of its biological productivity, but the potential harvestable crop wUl depend on the size and age structure of the population. A dascription of this structure in area B at the time of fish removal in 1948 and 1949 is pre- sented below . Age-frequency distribution In the various samples was determined by aging a number of fish within certain size ranges and then assigning ages to measured fish in these ranges on the basis of percentage composition of various size classes. Since there was only a small amount of overlap between the intervals, a reasonably accurate estimate of age compo- sition of the enti re population was obtained .

SIZE AND AGE STRUCTURE

Predators

Bowfin:--In the 1948 collection there were 28 bowfin. Of that number, 27 varied from 21 .0 to 25.9 inches in length ^Tahle 11). In 1949, 68

L^rgemouth bass :--Youiig-of-the-year of largemouth bass were aHmrtaTir in both years . In 1948 only two and three specimens of age groups I and n , respec'v^" -;s-ere recovered. In the following year l4 - fish of those

respective age groups and 3 of age group HI were taken (Table 12).

Northern pike: --Aging of scale samples with a high degree of certainty was not possible for northern pike so age groups cannot be defined. The numbers of specimens recovered in 1948 and 1949 were 16 and 18, respectively (Table 11). The smaUest fish in 1948 were in the 22.0-22.9- inch size class , and the largest exceeded 36 inches \n length. In 1949, 13 of the 18 fish ranged from 14.0 to 20.9 inches in length and the largest was less than 30 inches.

21

Table 10: — Average standing crops, in total and by certain species groups, of inland waters of States adjacent to the upper Mississippi River and of Area B.

Location	Number of waters	Aver a Panfish	ge pounds per Game Rough fish fish	acre Total 1/	Reference
Northern Minne s ota	52/3/	39	17	2	60	Peterson (I4O)
Northern Wisconsin	33/	31	h	103	139	O'Donnell (39)
Area B	u	36	29	112	32U	Present study
Southern Minne s ota	uuV	6U	12	283	375	Moyle, Kuehn and Biarrows (3Ua)
Southern Minnesota	68^	70	17	13	110	Moyle, Kuehn and Burrows (3ha)
Southern	^ /

Wisconsin 3=-'

3/

Iowa

2^'

3/

3/

Illinois 3-

Central Illinois

169

U8

97

6^/

25 237

10 690

lil;2

778

Illinois,

7/

50-55'

6/

33 172 363

600

l^oo-^oo

Juday, (2U); Threinen and Helm, (61); Mraz and Threinen~(36)

Speaker, (^l); Car- lander, (TT)

Thompson and Bennett (60): Bennett (6, 7)

Thompson (59) Thompson (59)

1/ Includes predator, catfish, and forage-fish groups, if present.

2/ Littoral areas only.

3/ Data from sources cited averaged by present authors.

^/ Littoral areas only; includes lakes with I4.O pounds or more of rough

fish per acre. 5/ Littoral areas only; includes lakes with less than IsO pounds of

rough fish per acre. 6/ Game fish and panfish combined. 7/ Floodplain lakes in Illinois River valley.

22

Table 11: — Length-frequency distribution of northern pike, channel cat- fish, bowfin, bigmouth buffalo, shortnose gar, longnose gar, and gizzard shad recovered from area 3 in 19U8 and 19ii9.

Size range			Spe!	z\es
(total length in inches)	Northern pike 19i4S 19149	Channel catfish	Bowfin	Bigmouth buffalo
	I9I48	19U9	19148	19I49	19)48	19U9
8.0- a. 9 9.0- 9.9 lo.n-10.9		1 1				u	3 2
11.0-11.9 12.0-12.9 13.0-13.9 lii.O-lli.9 15.0-15.9	? 1	1 2 3 3 k	2	1	3 1	2 2	7
16.0-16.9 17.0-17.9 IB. 0-13. 9 19.0-19.9 20.0-20.9	1 I4 3 1 1	5 7 7	1 5 6 6 7		1 1* 3 6	1 1	1 1
21.0-21.9 22.0-22 9 23.0-23.9 2)4.0-2)j.9 25.0-25.9	5 1 2 1	1	6 3 3 1	5 10 7 2 3	11 11 18 2 3
26.0-26.9 27.0-27.9 2G.0-2,'..9 29.0-29.9 30.0-30.9	1 1 2 1 1				1
31.0-31.9 32.0-32.9 36.0-36.9	1 1
To^.;bl	16 18	JjOl/	I4O	2a	0:1—	lo3/	lali/

1/ 1)063 not include six specimens not measured.

■^Z Doos not include four fish not measured,

3/ Dog."; not. include 12$ fish less than 3,0 inches in length,

ii/ rioes not include one specimen less than 3.0 inches in length.

23

Table 11 (continued)

Size range			Spec	ies
(total length in inches)	Shortnose gar 19 Ub 19 h9	Lonenose gar 19I48 19h9	jizzard shad 19^9
8.0- 8.9 9.0- 9.9				1
10.0-10.9 11.0-11.9 12.0-12.9 13.0-13.9 II4.O-II4.9				2 1	351 281 lU I42
15.0-15.9 16.0-16.9 17.0-17.9 18.0-18.9 19.0-19.9	1 1 6 2	1 7 3	3	1	28
20.0-20.9 21.0-21.9 22.0-22.9 23.0-23.9 2i4. 0-214.9	1	5 6 1? 10 5		3 I4 3 3 h
25.0-25.9 26.0-26.9 27.0-27.9 28.0-23.9 29.0-29.9	1	8		1 1
30.0-30.9 31.0-31.9 32.0-32.9 33.0-33.9 3a.0-3la.9
35.0-35.9 36.0-36.9
Total	12I/	57^/	3	2li	7161/

5/ Does not include 21 specimens less than 8.0 inches in length.

Z/ Does not include two fish less than 8.0 inches in length.

7/ Based on length frequency in measured sample; does not include 293

~ specimens less than 8.0 inches in length.

24

Table 12: — The age, length at capture, and minber of larganouth bass recovered from ares ? in 19'. S and "'.?';?.

		Nujiber	Estimated Percentage	Total length	(inches)
Aje	Xear	of fisr.	to-	oal nunber	of total
group	class	aged	in	age group	n'inber	.-ar.ge	Average
					I9I48
0	19US	7		li39		99.0
I	1914?	2		2		O.b	6.I4- 8.2	7.3
II	19146	3		3		0.6	1011.0	10.6
Total		12		U9l4	194?		—
0	19I49	0		8I4I		96.0		—
I	191j8	19		2I4		2.6	6.I4- 9.1	7.I4
II	19li7	10		10		1.1	11.5-12.9	12.0
III	19h6	3		3		0.3	13.14-15.3	I4.I4
Total		32		378		—

Tabls 13: — 'Hie age, length at capture, and number of saugers recovered irorr. area 3 ir. I9I40 and 19149.

		Number	Ssti.'Tiated P	'ercentage	Total length (inches)
Ase	Year	of fish	total n-onber	of total
group	class	aged	in age g;	rout)	nm.ber	Ranee Averaee
				19ij8
0	I9I48	2	8		25.8
I	I9I47	10	10		32.3	6.1j- 7.8 7.1
II	19u6	7	7		22.6	9.5-11.1 10.0
III	19U5	5	5		16.1	11.9-13.3 12.7
IV	19i4i4	1	1		3.2	— II4.5
Ibtal		25	31	19^9	—	— —
0	19I49	0	0		—
I	19i48	7	7		36.3	6.2- 8.6 7.3
II	19I47	10	10		52.6	9.i4-11.8 10.9
III	19I46	2	2		10.5	13.7-li4.li Ib.l
Total		19	19			—

25

Table Ih: — The age, length at capture, and nunber of bluegllls reoovered from area 3 in 19li8 and 191i9.

Number Estinsated Percentage Ttttal length (inches)

Tear of fish total number of total

class aged in age group number Range

Age

group

19lj8

0	19U8	8	399
I	19147	39	183
II	I9I46	50	55
III	191.5	k	ti
IV	19Ui	1	1
Total		102	61.2
0	19h9	0	3.103
I	19I18	17	862
II	19li7	29	29
III	191.6	U	1.
IV	191iS	1	1
Total		51	3,999

19h9

Average

62.1	—	—
28.6	2.5-1..I.	3.8
8.6	1..9-6.6	5.7
0.6	6.1-7.2	6.7
0.2		9.3

77.6		—
21.6	1(. 0-5.0	1..S
0.7	5.>7.2	6.3
0.1	6.7-8.6	7.6
		9.0

Sauger; --Five age groups of saugers were represented in the 1948 collection of 31 fish (Tab.e 13). Age groups 1, 11, and 111 accounted for 32.3, 22.6, and 16.1 psrcent, respectively, of the total number. Excluding age group 0, the specimens ranged from 6.4 to 14.5 inches in length. In 1949 there were no young-of-the- year among the 19 fish recovered and the oldest specimen was of age group 111. The 1947 year class was represented by a like number of fish in both years .

Walleye ;- -Of nine fish recovered in 1948, eight were of age group 0 and one was of age group V. The 1949 collection of 11 fish was not aged, but six varied from 3.8 to 7.5 inches and five from 17.2 to 22.2 inches in length.

Panfish

Bluegill : --Age groups 0-IV were present in both years (Table 14). In the 2 years age groups III and IV were represented by four and one specimens , respectively. The difference in numbers of young-of-the-year fish recovered in the two years (399 in 1948; 3,103 in 1949) is probably more apparent than real, since the 1949 collection vvas made approximately 1 month later in the year and the water was lower and clearer

than in 1948. This assumption is supported by the fact that more than twice as many specimens of the 1948 year class were recovered in 1949 as 1 -year-olds than were taken in the previous season as young-of-the-year. Age group 11 was more strongly represented in 1948 than in the following year. The largest fish in 1948 and 1949 were 9.3 and 9.0 inches in length .respectively.

Black crappie;--More black crappies of age group I were collected in 1948 than in 1949 but representatives of age group II were much more abundant in the latter year than in the former Table 15). The appearance of this strong 1947 year class in 1949 as age group II could not have been predicted on the basis of recovery data of 1948 when the fish were of age group I. The limited occurrence of fish of the 1945 year class in 1948 is repeated in the 1949 collection. Only four specimens of the 1944 year class were taken in 1948 but nine appeared in the collection a year later. This apparent strength of year class is not shown in the data for any other pan- fish species in either 1948 or 1949. A sharp decline in representation of older age groups was evident in both years. The largest fish from the combined collection was 12.8 inches in length.

26

Table l5:--The age, length at capture, and number of black crappies recovered from area B in I9I46 and 19^9.

		Number	Estimated Percentage	Total length	(inches)
Age	Year	of fish	total	number	of total
group	class	aged	in ag>	e group	number	Range	Average
				I9I48
0	I9I48	10	2	,056	96.0		—
I	191j7	27		52	2.h	I4.6- 5.8	5.2
II	19146	23		2h	1.1	6.0- 8.8	7.U
III	19h5	I4		U	0.2	9. 0-10. L	9.6
IV	I9U4	3		h	0.3	10.3-11.7	11.1
Total		67	2	,lijO 19149		—	—
0	19I49	0		9U	78.5	—	—
I	I9I48	12		36	3.1	'i.ii- 6.6	5.6
II	19ij7	11		196	16. Is	7.2- 8.8	8.3
III	19I46	li4		II4	1.2	9.0-10.2	9.8
IV	19h5	2		2	0.2	10.9-11.2	11.1
V	19i4lj	9		9	o.e	11.5-12.8	12.2
Total		UQ	1	,199	—	—

White crappie;--In 1948 the age-group composition of the white crappie was character- ized by the relatively high number of age group III fish and by the scarcity of young-of -the -year fish (Table 16). The latter deficiency cannot be explained on the basis of poor recovery since a large sample of fingerling crappies was col- lected and closely examined to separate the two species. Age groups I through III were well represented but only one specimen of age group IV was recovered. The corresponding numbers for 1949 were quite different. Age group 0 was well represented in that year but fish of age group II and over were relatively scarce. The apparent weakness of the 1948 year class indicated by the 1948 collection

was not borne out by the 1949 results. In the latter collection the 1948 year class (age group I) was strongly represented. The largest fish In the combined collections was 12.8 inches in length .

White bass; --Natural reproduction of white bass was very successful in 1948 but only one specimen of age group 0 was collected in 1949 (Table 17). This scarcity in the latter year may be indicative of a tendency of white bass to move out of backwater areas with advancing size. Evidence of natural reproduction was also lack- ing in the 1951 and 1952 samples collected later in the year than that of 1948 and fish of older age groups were not prominent in any of the four

27

Table l6:--The age, length at capture, and number of white crappies recovered from area B in I9I48 and 19i49.

Number Estimated Percentage Total length (inches)

Age Year of fish total rnunber of total

group class aged in age group nuirber

I9I48

Ranse

Average

0	I9I48	6	85	39.5
I	I9I47	28	73	33.5	I4.6- 6.8	5.I4
II	191*6	36	36	16.5	6.5- 8.2	7.9
III	19h5	22	22	10.1	9.3-10.7	9.9
IV	19U4	1	1	0,5	—	10.9
Total		93	218
			191)9
0	191)9	0	655	81.1	—	—
I	191j6	29	129	16.0	5.1- 8.0	6.8
II	19h7	h	9	1.1	8.5- 9.1;	8.9
III	191)6	9	9	1.1	10.0-11.2	10.7
IV	19b5	5	5	0.6	11.2-12.8	11.8
V	19ljl4	1	1	0.1		12.2
Total		I48	808

collections. Age groups 1 and II were repre- sented by only one fish each in 1948, and in 1949 by nine and one fish, respectively. One individual of age group III was found in 1949.

Yellow perch: --Age groups 0,1, and II of yellow perch were present in 1948 but only young-of -the -year and fish of age group I were found in 1949 (Table 17). These recoveries, together with those of 1951 and 1952, suggest that adult yellow perch were either not abun- dant in the vicinity or that they do not frequent the habitat type studied during the summer months . The largest fish in the combined collections was 7 .4 inches in length.

Catfish

Channel catfish: --Forty of the 46 channel catfish recovered in 1948 ranged from 8.0 to 21 .9 inches in length (Table 11). Within this measured sample 24 fish were in the 16.0-19.9- inch size range. In 1949 the size spread of the 40 specimens collected was 15.0 to 24.9 inches and 25 of these fell within the 18.0-21 .9-inch interval . No attempt was made to determine the ages of the channel catfish.

Flathead catf ish : - -Two flathead catfish with total lengths of 21 .2 and 21 .4 inches were recovered in 1948. None were observed in 1949.

28

Table 17: — The age, length at capture, and number of vrfiite bass and yellow perch recovered from area B in 19U8 and 19U9.

Number Age Year of fish

group class aged

Estimated Percentage total number of total in age group number

Total length (inches)

Range

Average

0	19148	3
I	19I47	1
II	19h6	1
Total		5
0	19149	1
I	19I48	9
II	19I47	1
III	19I46	1
Ibtal		12
0	I9I48	8
I	I9I47	11
II	19I46	1
Total		20
0	19I49	2
I	19148	15
Total		17

White	bass.	I9I48
l,58l4		99.9
1		0.1
1		0.1
1,586
White	bass.	I9I49
1		8.3
9		75.0
1		8.3
1		8.3
12		—
Yellov	r perch, I9I48
309		96.3
11		3.I4
1		0.3
321		—
Yellov	r perch, 19I49
$21		93.5
36		6.5
557		— ._

8.6-9.8

14.1-5. I4

2.6-2.8

I4.I4-6.I4

7.1 12.5

3.9

9.3

12.9

II4.3

l4.8

7.I4

2.7 5.3

29

recoverec.

Forage rish

id 5.6 through age groups 0 to \T (Table 20). Age

groups I through 'Vll were present in 1949 (26

-; fish) with a distinct mode in the distribution

represented by the 1947 \-ear class (57.7 per- cent). This strength of year class was not evident in the 194S data.

Gizzard shad: — In 1948 adult gizzaid shad were very rare, but is \'^4^ -Sige fish predomi- nated. Of the 1,009 cc - the latter year,

71- . " — 11.0: ' ches in length

(Ti :s differ-. , r resents the

most extreme variation in size-class structure betwesi the tw : - ' "' any one spjecies

?T3 the fish : in appreciable

:-. vears.

C£^p;--^

in aging earn ir;

;. Wis experiencec Dnd Tear of life.

groups were represente ^ - - - sample

which ri-rr: _7 - "" - - (Table

18). A- - . , -was

of age r r : Specimens of age group in

comprzsez i zistinct mode, saggesting the crrjrrence of a ~rrrr :^45 year class. Scale -S were r - ^ -4-' .

Spotted sucker: --.*.ge groups I, n, HI, V, and M of the 3p:::t: -_;serwere represente: in the 1948 colli - - ::?:- T=ble 19). Age grouje I (194~ — =7; . 1-43 year class) constituted 75.0 and 17.5 percent, re- spectively, of the t--: - — The 1944 year

class was missing - year class was

represeijtted ir- ; iish. In the 1949 col-

ler*'- ---•:- _ 1947 year class again

w£ .th 45 . 1 percent of the total .

iar class, of which only one was . — •-:._ m 1948, accounted for 15.0 percent of the 1949 collecticm. Two specimens of the 1944 year class we r -43 year

cla^- -^i- ?till prei-;.. ; :: .=a). It is

ar: it the 1948 sample gave little indi-

cation o: the real year-class strength, with the exception of the 194" hatch.

Fresrwater cra~x:--~' ■ -."

drum taken in the i->~i> collr

Northern river carpsucker:--Stx northern river carpsuckers. Carpiodes carpio carpio (Rafinesque). of age group 0. three of age group I and one of age group M comprised the entire

1948 collection (Table 18).

Northe— . rec rchorse. Moxostc

".orse:--Of the 24 northern ~a aureolum (LeSueur).

recovered in 1948 all but one were of age group 0. The single fish belonged to the 1943 year class (age group V) and measured 17.1 inches in lengfli (Table 18).

Bigmouth buffalo: --The 1948 collection of rigmouth buffalo included 125 fish less than 8.0 inches in length and 10 that ranged between 10.0 and 19.9 inches (Table 11). In the 1949 col- lection of 19 fish one was less than 8.0 inches in length. 16 ranged between 9.0 and 12.9, and two measured 18.9 and 20.8 inches. Difficult^" encountered in identifying annuli prevented assignment of individuals to age groujjs .

Smallmouth buiiaio : - -£:ght smallmouth i^jffalo, Ictiob-js bjbalus (Rafinesque), recovered - -49 rang- r en 9.4 and 14.1 inches and

all were of age group I . None was observed in 1948.

Comparison with other Mississippi River areas

Surber (54) found that the important fishes :- "he Mississippi River sloughs of the Tremp- ;_ _i.u, Wisconsin -Winona Minnesota area which were 15 ;:er were the black

crapr^ ~ : .^^ed, black bullhead,

birr.- w perch. The northern

pike, cowfin, and iargemouth bass were the principal carnivorous species but they were present in relatively lower numbers. The popu- ra B were similar but the pumjAin-

: ...ids. and yellow p)erch were less

impnrtant .

30

Table 18: — The age, length at capture, and nuater of carp, northern carpsuckerSj and northern r^dhorse recovered from area '5 in 19^8.

		K'jjsber	Estimated	Percentage	Tctal length (inches)
Age	Year	of fish	tctal number	of oO jal
group	class	agec	ir. age group	n-uacer	?-ar;ge Average

;am

0	19U8	10	1,023	93.9	—	—
I	19^7	12	12	1.1	10.5-lii.U	12.0
II	191.6	7	7	0.6	15.6-13.2	17.0
III	19U5	22	29	2.6	I8.I1-22.9	20.9
IV	19Uk	9	13	1.2	20.9-2I4.9	22.3
V	19I43	U	5	0.5	25.0-28.0	26.7
•	?	1	1	0.1	—	30. u
Ttotal		65	1,090	—	—
	191.8	0	Northern	carosucker	...
0	\j	60. 0
I	19I47	3	3	30.0	7.2-8.5	7.9
71	19I42	1	1	10.0	—	20.3
Total		h	10 I.'orther:	- redhorse	—	—
0	19I48	0	23	95.3	—
V	19^3	1	1	L.2	—	l-.l
Total		1	2I4	—	—

31

Table 19: — The age, length at capture, and number of spotted suckers

recovered from area B in I9I48 and 19h9»

Age group	Year class	Number of fish aged	Estimated Percentage total number of total in age group number	Total length (inches) Range Average
				191*8
0	19U8	0			—		—
I	19U7	2li	30		75.0	l*.7-6.l4	5.1*
II	I9I46	1	1		2.5	—	10.1
III	191^5	1	1		2.5	—	13.5
IV	19UI4	0	0		0.0		—
V	19ij3	6	7		17.5	15.6-17.5	16.8
VI	19^2	1	1		2.5	—	17.1*
Total		33	1*0	191*9	— "■—	—	—
0	19ij9	0	0		—	—	—
I	191*8	ill	38		33.6	6.7-0.1^	7.7
II	191*7	30	51		1*5.1	11.3-13.2	12.2
in	191*6	3	17		15.0	1J*.6-15.)4	15.0
IV	191*5	2	1*		3.5	15.7-16.6	16.2
V	191*1*	2	2		1.8	16.14-16.8	16.6
VI	191*3	1	1		0.9	—	16.5
Total		52	113		—	—	—

32

Table 20: --Age, length at capture, and n\imber of freshwater drum recovered from area B in 19)i8 and 19U9.

Age group	Year class	Number of fish aged	Estimated Percentage total number of total in age group number	Total length Range	(inches) Average
				I9J48
0	19h8	2	7		36.8
I	19I47	2	2		10.5		7.6
II	19I46	3	3		15.6	11.0-11.9	11.5
III	19I45	1	1		5.3		II4.2
IV	19hh	2	2		10.5	15.2-16.0	15.6
V	19143	3	3		15.8	16.7-17.2	17.0
VI	I9I42	1	1		5.3		17.9
Total		111	19	19^9	---	-— —	-~
0	19149	0	0		—		—
I	I9I48	h	I4		15.I4	8.2-IO.I4	9.I4
II	1914?	15	15		t>i.7	10.8-13.0	11.9
III	19146	1	1		3.8		15.0
IV	19145	2	2		7.7	15.3-16.7	16.0
V	191414	2	2		7.7	18. 2-18. I4	18.2
VI	19U3	1	1		3.8	—	17.9
VII	19J42	1	1		3.8	—	19.9
Total		26	26		—	—	—

33

Of the species represented in area B, only the largemouth bass, bluegill, black crappie, and white crappie were present in sufficient numbers and sizes to warrant com- parison of population structure with those In other sections of the river. In the following comparisons, emphasis is placed on longevity of life since the limited collections and the variable methods by which other populations were sampled make other comparisons of doubtful value.

Largemouth bass

The oldest largemouth bass in the com- bined collections of area B was of age group III. The oldest fish taken in the Illinois-Missouri section of the river was of age group V (Upper Mississippi River Conservation Committee, 62).

Bluegill

The combined 1948 and 1949 collections from area B included only one bluegill of age group IV and only four of age group III. Kelley (25) found the oldest fish collected from the Mississippi River in the vicinity of La Crosse, Wisconsin in the latter half of May to be of age group V . A gradual decline in representation of older fish was apparent as netting progressed and by September age groups IV and V had disappeared from the catch. He ruled out migration as a factor and ascribed the decline primarily to natural mortality. Meehean (32) found no bluegills beyond age group III in Mississippi River sloughs of the Trempealeau area. The oldest fish netted in the Illinois- Missouri waters of the Mississippi River were 5 years of age (Upper Mississippi River Con- servation Committee, 62).

Black crappie

The oldest black crappies in the 1948 and 1949 collections from area B were of age groups IV and V , respectively. Kelley (25 ) noted a decline in trap-net catches of 4- and 5- year-old fish from May to September and con- cluded the principal cause to be natural mortality. The oldest specimen collected in the Illinois - Missouri waters of the river was of age group VI (Upper Mississippi River Conservation Committee, 62).

White crappie

In area B in 1948 the oldest white crappie was of age group IV (one specimen), and in 1949, one fish of age group V was collected . Kelley (25) noted that by September, very few 4- and 5 -year-old fish were being caught in the La Crosse area and again attributed the loss primarily to natural mortality. The oldest fish taken in the Illinois-Missouri section of the river was of age group VI (Upper Mississippi River Conservation Committee, 62).

General consideration of age structure

Data presented in this section suggest that these species in the upper Mississippi River back- waters are generally short-lived. Results of an investigation in several similar areas near La Crosse in 1948 tend to substantiate this hypothesis (Kelley, 25). Few fish of the species studied at La Crosse and in the present investigation were found to be greater than 5 years of age. This age structure is in contrast to much of the published data which show a tendency in many waters of the north central States for populations of the species considered to be longer-lived.

GROWTH RATES OF FISH

Butler and Smith (8) and Appelget and Smith (1) reported on growth of the freshwater drum and the channel catfish in the upper Mississippi River, respectively. Eddy and Carlander (15) presented limited growth-rate data on the white bass and spotted sucker from the Mississippi River and a general summary of the growth rates of several species from the Illinois -Missouri waters of the river was reported by the Upper Mississippi River Conservation Committee (62). Because the number of scale samples taken from each species was relatively small , no attempts have been made to validate the scale method for the present collections . Adequate validation of the method for some of the species included here has not yet been presented but successful employment of the scale method of aging and gro\\th analysis by various investigators is considered to be an adequate basis for its acceptance in the present case. Eddy and Car- lander (15) presented general growth summaries for all species herein studied except the orange- spotted sunfish, Lepomis humilis (Girard), Smith

34

and Moe (49) and Moyle (34) also reported such summary data for all species considered here except the white crappie, spotted sucker, orangespotted suniish , bigmouth buffalo, and smallmouth buffalo.

A rectilinear relationship between total body length and length of the anterior scale radius was used for all growth calculation. The values of the correction for length at time of scale formation, where used (Table 21), were taken from various sources except for carp. Following the method of Butler and Smith (8) for examination of scale pocket formation, the average total length at time of scale formation (in the area of the body from which samples were taken) of carp was found to be 0.9 inches.

Table 21: — Values of correction for length at time

of scale formation in the various species used in growth calculations.

Species

Correction f Total length in inches)

Largemouth bass

White bass

Blue gill

Bigmouth buffalo

Smallmouth buf faT o

Carp

Black crappie

White crappie

Freshwater drum

Yellow perch

Sauger

Spotted sucker

Orangespotted sunfish

0.8

0.0

0.86

0.0

0.0

0.9

0.8

0.8

0.8

0.5

0.7

0.0

0.0

each of these species the difference in numerical representation of the 1944 and 1945 year classes (age groups III and II) was extensive. Because so few specimens of the former year class were present, significant figures for most species are limited to age groups I and II. In general, very poor growth was shown for all species in 1945 . Since that year class strongly affects the weighted calculations due to its strong representation in the samples compared to other year classes, the resulting data are not con- sidered to be representative of the general growth picture for the area. Butler and Smith (8) found similar conditions in the 1945 year class of the freshwater drum.

Table 22; — Grand average calculated total lengths in inches at time of annulus fomation of various suecies, sexes conbijied, from Killer Lake, August 15, 19li7.

Species	Number in sanpl by year class	.e	Total nuflter		Annulus
	»i3	Wlit	191.5	Hit	I	11	III	Tl
Largenouth basa			27	3t>	65	J.2	6,C
EaueglU			63	17	101	1.6	3.6	6.9
Black crappie			hh	I.I1	69	2.0	li.li	6.1
White crappie	1		16	12	30	1.9	lj.7	8.0	9.1
YelloK perch	1		35	68	109	2.6	5.7	6.9	10.5
Northern pike			21	38	60	8.9	15.7	20.8
Sauger			7	7	Ui	1..5	8.6
Spotted sucker		5	36	35	76	1.9	6.7	11.7

Back calculations of length at various annuli were made by the use of manila tag- board strips marked from the projected scale image and a straightline nomograph (Carlander and Smith, 13). Two scales from each sample were read to minimize the influence of varia- bility of the scales . Size of the samples and incomplete sex data did not permit separate calculations for each sex.

References in this section to the number of year classes or age groups present exclude young-of-the-year (age group 0).

Miller lake

Growth -rate calculations were made for eight species from Miller Lake (Table 22). For

Areas A and B

The growth- rate calculations for various species from areas A and B have been combined where an increase in the size of the sample of poorly represented year classes would result. It is assumed that fish from both areas represent the same population because: 1) there is agree- ment in the growth -rate calculations among well -represented year classes of certain species; 2) both areas open upon the same unobstructed channel during low water stages; and 3) at high water levels both are virtually contiguous and offer an opportunity for random distribution of fish over the entire area . Robert Sharp!/

7/Personal communication, December Ih, 1951.

35

demonstrated that fish will move into flooded areas duririg high water stages . He eradicated fish from a rearing pond at the U.S . Fishery Station, Guttenberg, Iowa, which had been dry in the fall of 1950 but from which 124 pounds of fish per acre were obtained after recession of the flood water in the spring of 1951 . Fish had access to the pond for approximately 2 weeks, during which time 16 identified sp)ecies had moved into the area . Random movement of several species into and out of a Mississippi River backwater area has also been reported (Upper Mississippi River Conservation Com- mittee, 64). Surfaer (54) related similar activity in Mississippi River sloughs to changes in water level.

Bluegill:--The growth of bluegills was determined from 169 fish collected from area A. and area B, 1948 and 1949 . Althoi jh this sample was larger than that of any other species examined, the oldest age group was in its fifth season of growth (age group IV) and was repre- sented by only two specimens . The average calculated total lengths at the end of each year of life of the four age groups present were 2.0, 4.4, 6.4, and 8.4 inches, respectively (Table 23).

With two exceptions , the growth of the black crappie in the Fountain City backwater areas was generally faster than that cited in several waters in various localities (Table 26). After the third growing season, average calcu- lated growth in areas A and B was greater than the Michigan (Beckman, 1949) and southern Wisconsin (Mackenthun, 29) average total lengths at capture for corresptonding age groups.

-3c^ail iTW^g* uluilllta to^al Ingtbs la Inches at zImc ot wmoljis foisatioD of the blTiegi 11, se2BS oambLnedf froa =Tes A, 19LS, ano ares r, IptiS aid TSIS.

Tear	Tear of ^srtare	He group	Jhmber of spedaens	Area of		t— ^	-lus
:;liSS	I	-^	HI	:v
ISuS	19 i9	1	17		3	2.6
191.7	ISliS lSi:8	I	8 39 29		B S	2.2 2.2 2.0	li.7
ISliO	191i8 15i9	n n m	li 50		1 3 3	1.7 1.9 1.8	3.9 li.3 a. 3	6.6
isas	19!j8 191,6 19i9	in 111 17	2 1		1 B 3	1.5 1.6 2.7	3.9 li.O li.9	6.1 5.9 7.2	8.3
iS'Ji	i9iie	IV	1		3	2.2	5.1	7.5	.5
2raia	arera^ calala^ec Imgth				2.0	!i.l>	6.1.	&.U
i^mber	or fish		169			169	ICi	12	2

The bluegills collected in areas A and B grew much faster than those from waters in various localities listed in table 24 . The average calculated total lengths of age groups III and rV exceeded the average total lengths at capture for the corresponding age groups of the bluegill in 17 southern Wisconsin lakes (Mackenthum, 30) and were larger than the Michigan average total lengths at capture for the same two age groups (Beckman, 4) .

Black crappie:--Growth rate of the black crappie collected in area A, and area B in 1948 and 1949 was calculated from 132 scale samples . Since the five year classes found in these areas were all well represented, we believe the average growth calculated from this ccliection more truly represents actual conditions than those determined for other species. *c the end of each of the first five growing seasons , the black crappie averaged 2.7 , 5.7, 8.5, 10.3, and 11.4 inches, respectively, in total length (Table 25).

blasgill fr3B different localities.

- =■ — -■			:		^^T	17
ij-==3 1 £r.i :-	-.3=. ^.^				i.k	i.l
»^-^TT=?!=-ta axersge	!bjle fji)				..9	6.1
Iraa, Hed =sb Leje	LeKis (27/		...	J —	6.1	7.2
Ixa, Ssst Zajce	U«ls f27)		1.7	3.6	5.6	7.0
"=K3. Lakf Abqsabl	EssxscO. 'n)		1.9	3.7	1.7	5.6
Z-x&f I3c€ LSJce	a=Sr (hS)				..?	6.!.
:i:i=3i5. fSTC-late are rage	3ea=ett (6)				-9	6.0
53-lairg ST?r«^	aicter 'Uli'		1.5	3.0	!i.8	6.5
2Mc 3T*rag^	P.oact an: grans	t3)l/	1.6	3.6	5.1	6.0

V lT*r3f= grawti: rvL^jr Ue by CaJ-'a-T^er 'l^Cdj;

36

Table 25 :-

■GrV9d jTTJee caHcalatge total lei^ths la i: HsaiLns fematiop of tf^ black i-r«spie, :

Tear Tear ;f lr« class ca=tnre ?t^=p

icr or irea zf

19U7	Iji	t£	:3 n 11
l>i6	191.8 lSu9	II ni	t li
19b5	ISttS ISiS	m IT	2
151J>	19t8 19iS	17 7	3 9
-jrax	arrerar« calsilatac
	lc=,-J:

2.8

2.8

2.7 6.0

2.? 5.5 2.6 S.6

1.6 1.9

5.5

8.5 10.3

2.5 5.7 e.7 10.2

!=«», Hid H3» '-■" :«»U '195CB/27;

10.3 ll.!i

2.7 5.7 5.5 1C.3 132 70 32 111

:.0 6.9

6.6

5-6

e.7

9.0

—jT^^ sverace islculated ujzal lc:gti:£ in ar«a A, I?_r. area r. I^_8 arc l7~=.

a; iTE 3f

~5; — Calf.'.l =fifKi xo^al lec^^&a in l->"*^^ a^ '

■ of i?«

-ire gi^^

5-.=ibeT =f Area

19.S	1=.;	-
l?a7	ISl-S 19!!S 19iS	I n
l?i6	i9iia 19i3 191:9	HI
ISio	ISIe 19t8 19i.9	m III 17

Grx>d aT«ra^ c«1 ^1 ^tpri laigta

S;xiber of f1 -ih

li 23 h

12 36

165

3 =	2.7 2.1	6.]i
1 3 3	2.- 2.3 2-5	i.0 5.9 6.2	9.6
k 3 3	1.7 1-8 2.0	6.2 6.1 6.3	9.2 3.S 9.k	11.1
3 5	2.3 2.3	5.5 5-3	6.3 9.2	ID J. iS.7
	2.6	6.0	9.J.	10.9
	165	5ii	a2	7

Irssjz £ as: r Presaz^ s^o=7

loTa, ?n^ Has 7 .aire leicj (195C'a]

"iraesoti arerace irii; C19iiS)

Iz.-^ g-jj ^bcls Pood Hrscer aoc :

2.S 6.0 9.1 U.9 11.7 3J. 7.6 3Js 9.9 11-2 2.5 5.5 5.7 S.9 10.!

QZZS3 areraje lova, ZLaar X-are

•I9i3)^ 2.6 5.6

-eidj .-r--^

ier il9a2) 2.8 5.5 8.6 10.2 11.5

9.2 10.5 2.0 5.1 7.k

2J. 5.3 6.7 7.7 £.i

1.' aiti-.a^

White crappie:- -Growth -rate calculations were made from 165 scale samples from the white crappie from area A, and area B, 1948 and 1949 . Five age groups were represented but only one fish of age group V was present. The generally poor growth in 1945, previously referred to, is most clearly demonstrated in these calculations , although it is also evident in those for the bluegill and black crappie. The average calculated total lengths at the end of each of the first five growing seasons were 2.6, 6.0, 9.1, 10.9, and 11.7 inches (Table 27).

The growth of the largemouth bass in these areas was considerably more rapid than the Wisconsin average (Bennett, 5), the Minnesota average, and that in three Iowa lakes (Lewis, 27; Ruhr, 45). It was also faster than the rate shown by this species in southern Wisconsin waters (Bennett, 5) and in Spwrtsmens Lake, Illinois (Thompson and Bennett, 60). Bennett (6) reported a faster growth rate in Onized Lake, Illinois. The average total lengths at capture exceeded those of the corresponding age groups in the Michigan average (Beckman, 4).

The growth of the white crappie in areas A and B was generally faster than that shown for other waters in table 28 . Average total lengths at capture of age groups IV and V approximated those of Lake Decatur, Illinois, which Hansen (20) considered to repre'T nt average or slightly better than average growth for the State .

Largemouth bass:- -Growth rate was determined from the scales of 32 fish collected during the 1949 poisoning of area B. Only three age groups were represented in the entire population. Grand average calculated total lengths at the time of annulus formation for age groups I, II, and III were 4.0, 9.6, and 12.8 inches, respectively (Table 29).

i«bl« 29: — Orand oversga calculated total lengths In Inches at tine of

amuluB formation of several species, sexes coobined. from the ccRblEcd area A. l?u.^, and area B. 191*8 and 19ij9, collections (munber of spsclJions shotfn In parentheses'.

Total Spedas number of 8p«clJRens

Largenoutb baas

Sugar

Carp

freab water

Anm

li.O(32) 9.6(13) 12.9(3)

l4.9(W) 9.0(25) U.9(e) 13.«1)

7.7(51i) Ui.6(U) 19.1(35) 22.1(13) 25.9(U

5.0(37) 9.6(31) 12.5(13) li.S(u) 16.5(7) 17.5(3) 19.3(1)

5.7(U) 10.7(2) 13.W1)

Sauger:- -Calculation of growth rate was made from 42 scale samples collected in area B in 1948 and 1949 . Total lengths at the end of each of the first four growing seasons were 4.9, 9.0, 11.9, and 13.6 Inches, respectively (Table 29).

The growth of saugers in area B was much faster than that in Lake of the Woods, Minnesota (Carlander, 9) and was also well above the Minnesota average. It closely approximated that in Lake Erie (Van Oosten, 67).

Carp:--Growth calculations were made from the scales of 54 carp taken in area B in 1948 . Difficulty was encountered in the inter- pretation of the various apparent annul! on the scales from fish over 2 years of age and 12 scale samples of the original 66 in the collection were discarded. A similar problem was reported by English (12) and the Upper Mississippi River Conservation Committee (62) . Average calcu- lated total lengths at the end of each of the first five growing seasons were 7 .7, 14.8, 19.1, 22.1, and 25.8 inches, respectively (Table 29).

The growth rate of carp approximated that of the Minnesota average. English (1/7) reported a faster growth of carp in Clear Lake, Iowa .

Spotted sucker: --Growth was calculated from a collection of 85 scale samples taken in area B in 1948 and 1949 . Six age groups were present but age group VI was represented by only one fish in each of the 2 years . The average calculated total lengths at the end of each of the first six growing seasons were 2.4, 8.0, 11.2, 13.8, 15.6, and 16.3 inches respectively (Table 30).

38

Table 30: — Grand average calculated total lengths in inches at time of annulus formation of the spotted sucker, sexes combined, from area B, 19146 and I9L9.

Year	Year of capture	Age group	Number of specimens			Annulus
class	I	II	III	IV	V	VI
I9I48	I9I49	I	II4	3.3
I9I47	19U8 I9I49	I II	214 30	2.5 2.2	8.7
I9I46	I9I48 I9I49	II III	1 1	1.3 1.9	7.1 7.3	12.8
I9I45	19^6 I9I49	III IV	1 2	2.2 2.I1	7.I4 7.3	12.3 11.7	111. 6
I9I4I4	iQa9	V	2	1.7	5.1i	9.7	12.9	15.3
I9I43	19148 191.9	V VI	6 1	2.0 2.3	6.9 5.8	10.9 9.5	IL.O 12.5	15.9 la.l	15.6
I9I42	19I48	VI	1	2.0	7.1	10.9	13.8	15.7	16.9

Grand average calculated length

Number of fish

85

2.h 8.0 11.2 13.8 15.6 16.3 85 I47 16 12 10 2

Freshwater drum:--Growth calculations were made from a collection of 37 fish from area B in 1948 and 1949. Seven age groups were present but age group VII was represented by only one specimen. The average calculated total lengths for age groups I- VII were 5.0, 9.6, 12.5, 14.8, 16.5, 17.5, and 19.2 inches, respectively (Table 29). These determinations exceeded both those repwrted by Van Oosten (66) for Lake Erie and by Kuehn (26) as the average for three Minnesota lakes .

White bass: --The growth rate of the white bass was determined from a collection of 11 scale samples. Three year classes were

represented but only one fish of each of the two older age groups was included. Calculated total lengths for age groups I , II , and III were 5.7, 10.7, and 13.4 inches, respectively (Table 29). This growth exceeded the Minnesota average and that in Lake Erie (Van Oosten, 67), and approxi- mated that in Clear, Storm, and Spirit lakes, Iowa (Lewis, 28; Sigler, 46, 47).

Yellow perch:- -All but one of 27 yellow psrch collected in area B in 1948 and 1949 were of age group I, the single exception being of age group II. The average calculated total lengths of age groups I and II were 2 .6 and 6 . 1 inches , resp>ectively .

39

Bigmouth buffalo:- -The average calculated total length of age group I, based on a collection of 16 fish of that age group from area B in 1949, was 5.1 inches. Annuli could not be identified on scales of two larger specimens collected at the same time.

Smallmouth buffalo:- -Eight smallmouth buffalo were collected in area B in 1949. All were of age group I and the average calculated total length at time of armulus formation was 5 .8 inches .

Orangespotted sunfish:--Of 18 fish col- lected from area A, all but one were of age group I, the lone exception being of age group II. The average calculated total lengths of age groups I and II were 1 .1 and 2.6 inches, respectively.

Comparison of growth in areas A and B and Illinois waters of the Mississippi River

General growth-rate information for several species in the Illinois-Missouri waters of the Mississippi River were reported by the Upper Mississippi River Conservation Com- mittee (62). Data for six species taken from this report, together with a summary of findings of the present study, are shown in table 31 . Since the growth figures for the lower section of the river appeared in a brief tabular form with no details concerning the manner of calcu- lation, a precise comparison is not possible. In addition, growth of certain species was based on average total lengths at capture for which the dates are unknown.

The growth of both the black and white crappies in areas A and B was faster than that for these species in the Illinois-Missouri waters of the Mississippi River . Reliability of this

Table 31: --Growth rates of six species in areas A and B and Illinois- Missouri waters of the Mississippi River expressed as total lengths in inches. Except where indicated, calculated lengths are shown.

Species	Number of specimens			Annulus
	I	TT	in	IV	V
Largemouth bass
Areas A and B	32	li.O	9.6	12.8
Illinois-Missouri	119	u.a	8.6	11.1	12.9	1U.2
Blue gill
Areas A and B	169	2.0	U.li	6.I1	S.h
Illinois-Missouri	105	3.0	5.3	6.6	7.3	7.8
Black crappie
Areas A and B	132	2.7	5.7	8.5	10.3	11. 1
Areas A andl/	6)4	5.1	T.h	9.6	11.1
Areas A and^/	U8	5.6	8.3	9.8	11.1	12.2
Illinois -Mi ssouri3/	1U2	—	5.7	7.6	8.6	9.6
White crappie
Areas A and B	165	2.6	6.0	9.1	10.9	11.7
Areas A and Bl/	117	5.I4	7.9	9.7	10.9
Areas A and B2/	as	6.8	8.9	10.7	11.8	12.2
Illinois-Misaouri3/	220	5.3	7.2	8.1,	9.8	10.2
Freshwater drum
Areas A and B	37	5.0	9.6	12.5	11.8	16.5
Areas A and Bl/	11	7.6	11.5	lh.2	15.6	17.0
Areas A and B?/	26	9.1.	11.9	15 0	16.0	18.2
Illinois-MissouriV	303	5.5	8.9	11.2	12.5	lh.3
Sanger
Areas A and B	U2	14.9	9.0	11.9	13.6
111 i nois -Missouri	lib	5.3	10.8	10.8	U.S

1/ Average lengths at time of capture, July 6-7. 19U8. 2/ Average lengths at time of capture, August 3. 19li9. 3/ Average lengths at time of capture, 19lilj (no dates given).

40

conclusion is enhanced by the availability of comparatively large samples from both regions and by demonstration of greater average calcu- lated lengths of age groups III, IV, and V of fish from areas A and B than of average lengths at capture of fish in cor responding age groups from the Illinois-Missouri section. Growth of the white crappie In the Fountain City backwaters also exceeded that reported by Hansen (20) at three stations in the Illinois -Iowa waters of the Mississippi River. Of the two species, the white crappie grew faster in both the Fountain City area and the Illinois-Missourl-Iowa section (Bamickol and Starrett, 3).

The freshwater drum also exhibited faster growth in areas A and B than it did in the Illinois - Missouri section of the river. Reasonable agreement between the growth data in the present study and those of Butler and Smith (8) tends to support this conclusion. Average calculated lengths of advanced age groups of fish from the Fountain City areas exceeded the average lengths at capture of corresponding age groups in the lower part of the river.

On the basis of annual length increments and on calculated lengths of the oldest age group common to samples from both sections of the river, growth of the bluegill and largemouth bass appeared to be faster in the Fountain City areas when it is compared to that in Illinois - Missouri waters; however, because collections of older-age fish of both species were limited, this evidence is considered to be weak.

Growth of the sauger appeared to be slower in areas A and B than in the lower section of the river.

Appelget and Smith (1) reported a growth rate of the channel catfish in Iowa -Wisconsin waters which apparently was slower than that in the Illinois -Missouri section (Upper Missis- sippi River Conservation Committee, 62). Bamickol and Starrett (3) reported the growth of this species to be faster in the Illinois- Missouri section than in Illinois -Iowa waters of the river.

The foregoing comparisons tend to confirm the ratings given by Hatner (41) concerning watei

quality in relation to fish production in the upper Mississippi River. He found that in comparison with waters producing good fish fauna, the Mississippi River would be rated good in the upper section and only fair in the lower section. However, recent findings, which indicate faster growth of the channel catfish and sauger in the lower section than in the upper portion, demon- strate that the fish species themselves must be given primary consideration in any evaluation of fish-growth potential of a water.

General consideration of growth

Without exception the growth rate of each species examined in the present study exceeded-' those previously cited as averages of two or more waters in Minnesota, Wisconsin, southern Wis- consin, Illinois, Michigan, northern Indiana, and Ohio. The growth of certain species also exceeded or approximated that reported for individual waters in Illinois, Indiana, Iowa, and Minnesota, with the following exceptions: 1) carp in Clear Lake, Iowa; 2) largemouth bass in Onized Lake, Illinois; and 3) black crappies in Onized Lake, Illinois, and Red Haw Lake, Iowa. It is evident, considering the geographic region and the latitude, that the growth of the fish species studied from areas A and B was comparatively fast .

FACTORS INFLUENCING PRODUCTIVITY AND PORJLATION DEVELOMENT

Detailed investigation of conditions which influence fish production was not attempted in the present study. The rather limited data from other areas, however, which compare environ- mental factors with standing crops of fish justify a short discussion of observed conditions and related data from other sources. Among the elements most likely to affect population levels are water and soil fertility, food availability, species composition, and water-level fluctuation.

8/Average total lengths of the younger age ~ groups were less than those shown from other studies in certain cases but those of the older age groups were consistently greater in the present study.

41

Water and soil fertility

Water fertility . --It is generally recog- nized that fertility of surface water is primarily dependent upon fertility of the watershed from which it drains. A major share of the 47 per- cent of Minnesota land classed as good to ex- cellent for general agricultural production (Engene and Pond 2^) lies in the upper Missis- sippi River drainage. It includes much of the Clarion -Webster soil association which is unsurpassed by any other In the State for com production (McMiller, 31^) . It might then be expected that the water which drains from this region would also be fertile. Water analyses V were nin on samples collected in area B and vicinity on October 3, 1955 and July 24, 1956 and in the main channel at La Crosse, Wiscon- sin on September 10, 1956 (Table 32). Concen- trations of total phosphorus in and near area B ranged from 0.091 to 0.114 ppm and those of total nitrogen from 0.69 to 1 .43 ppm. The average phosphorus -nitrogen ratios in water samples collected October 3, 1955 and July 24, 1956 were 1:8.2 and 1:10.9, respectively. Total alkalinity ranged from 100.0 to 115.0 ppm among the combined samples from area B and vicinity .

Moyle (33) reported that total alkalinity and total phosphorus appear to be the most valuable indices of lake productivity in Minne- sota waters. Lakes with a total alkalinity of 91 ppm or more were classed as high in both fish and plant productivity. Those with a total phosphorus content (unfiltered samples) of 0.051 to 0.10 and 0.11 to 0.20 were rated good and very good, respectively, in terms of phosphorus fertility. Moyle found the average fish yields from hard water ponds with total phosphorus exceeding 0.05 ppm to be highest when total nitrogen ranged from 0.51 ppm to 1 .0 ppm although nitrogen appears to be only occasionally a limiting factor in the productivity of Minnesota waters.

The basic compx^nents generally associated with fertility were found in the present study to equal or exceed those values described above which are indicative of heavy fish production and it is concluded that chemical fertility of the upper Mississippi River is high and capable in that regard of supporting a fish population at a proportionate level .

Bottom soils. --The importance of bottom soils in fish culture in Europe is described by Neess (38) in his review of numerous papers. The bottom soil in area B was a silty clay in texture and had a organic content of 7 .49 per- cent (Table 33). The soils of both the side channel adjacent to area B and the main channel were of a coarser texture and contained less organic material.

In a series of Minnesota walleye rearing ponds, Dobie (14) found higher fish production in ponds with fine-textured soils than in those with the bottom composed of coarse material . Wood (68) concluded that the availability of essential plant nutrients in the bottom soils is one of the two most important factors affecting the productivity of impoundments .

The pressure of fine-textured soil with a higher organic content than that associated with the coarser soils of the adjacent lotic environ- ments suggests that the backwater areas in the upper Mississippi River represent a major component of the entire fish-producing habitat.

Food availability

That fish production is directly related to the abundance of food in plankton or macro- invertebrate form has often been suggested.

Surber (54) found an abundance of phyto- plankton and rotifers in samples from upper Mississippi River sloughs. He reported Cyclops, chironomid larvae, and ostracods to be the "animal staples" in these waters.

9/ Analyses were run at the laboratory of the Minnesota Department of Conservation, Bureau of Research and Planning, St. Paul, Minnesota.

Comparison of bottom fauna and epifauna production in 1929-30 with that in 1953 in three sloughs located approximately 20 miles below Fountain City was reported by the Upper Mississippi River Conservation Committee (65) (Table 34). In the 1953 samples, copepods.

42

Table 32: — Results of chemical analyses run on water samples collected in area B and vicinity on October 3i 1955 and July 2ii, 1956 ajid in the main channel at La Crosse, Wisconsin on Seotenber 10, 1956. All values are expressed in parts per million.

3ul- Total Organic Total Total

Location fates phos- Clilorides Am^nia nitrogen nitrogen alka-

ohorus Unity

Area B, surface

Area B. li-foot depth

Side channel, surface

Main channel, surface

Main channel, 6-foot depth

Area B, surface

Area 3. U-foot depth

Main channel, surface

Main channel, surface

Area 3 and vicinity, October 3, 1955

16.0 0.095 Ij.O

18.0 0.120 lj.2

0.12 0.66

0.18 0.59

19.0 0.091 h.O 0.15 0.36

16.0 0.105 I4.I4 0.20 0.51

17.0 0.098 I4.O 0.18 O.Uh

Area 5 and vicinity, July 2!i, 1956

66,0 O.llij 6.0

71.5 0.109 6.3

0.00 0.96

0.00 1.11

66.0 0.116 6.0 0.00 1.00

La Grosse, Wisconsin, Seoteaber 10, 1956

26.0 0.171i 8.1 0.03 0.75

0.32	102.5
0.69	102.5
0.98	103.3
0.33	100.0
0.33	101.3

1.21

1.!j3 1.07

115.0 113.8 115.0

0.79 127.5

Table 33: — Texture and organic material content of bottom soils of

area 3. the adjacent side^hannel, and the main channel collected October 3, 1955.-

Location

Texture

Area B Side channel Main channel

Silty clay Coarse loamy sand Coarse sand

Percentage of organic material

7. a?

2.6i4 O.7I4

1/ Analyses were run at the laboratory of the Minnesota Department of Conservation, Bireau of Research and Planning, St. Paul, Minnesota.

43

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ip^c-E 2,: 13.:»:: 15.oCc 12,5=5 11,X5 3Ji,lC7

2?i 1,237 1_5 5,2S6 3D3 3,2=5

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W^Z. TT il^6C= ». ::>ZTZ~:T.

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Information of a similar nature was pro- vided by Robert Sharp 11/ concerning movement of fish into a previously dry rearing pond near the Mississippi River at the National Fish Hatchery, Guttenberg, Iowa. Fish had access to the pond after a rise in water level for approximately 2 weeks, during which period 1 ,240.2 pounds (124 pounds per acre) of fish had entered the area, as shown by subsequent eradication (Table 35). The species comprising the greatest weight were carp, bowfin, buffalo, black crappie, and shortnose gar, in that order. Largemouth bass and black bullheads were also prominent.

Falling water levels during the winter were accompanied by a definite movement out of backwater areas in pools 8 and 9 by carp, northern pike, crappies, spotted sucker, and bowfin (Upper Mississippi River Conservation Committee, 63). Movement of these fish was intensified by a sharp drop In the water stage . Conversely, nets set under the ice to block completely the outlet of a backwater lake near La Crosse, Wisconsin, demonstrated only ran- dom movement during a 43-day period when only minor water-level fluctuations occurred (Upper Mississippi River Conservation Committee, 64).

The catch of gill nets set in and just out- side area B approximately 1 week after the 1948 investigation provides further evidence of fish movement into backwater areas from another source (Table 35). This movement cannot be correlated with changes in water level, but it does suggest that backwaters which become de-populated through drawdown or winter-kill are apt to be invaded as soon as suitable con- ditions are re-established.

Comparison of water levels (Table 37) with population estimates in area B in 1948, 1949, 1951, and 1952 fails to show any relation between water-level fluctuation and standing crop. The greatest short-term changes in level were between 6 BA July 31 and 7 AM August 1 , 1949 and between 7 AM and 6 I^ August 1 , 1949

when a rise of 1 .03 feet and a drop of 0.8 feet, respectively, occurred. The highest standing crop was found in the August 3, 1949 operation. In view of previously cited data the sharp rise in water level mig^t account for a large influx of fish, but conversely the more rapid drop (though not as extensive) immediately following would exp)ectedly have initiated egress . Of the 4 years, levels In 1948 prior to poisoning were the most stable, yet production of rough fish, the group purportedly most influenced by water-level change, was second only to that of 1949, while the standing crop of panfish, the group probably least affected, was the lowest of the four estimates .

SUMMARY AND CONCLUSIONS

The oljectives of this study were to de- termine the productivity of and the fluctuations in the populations from year to year, the popu- lation structure, and the rate of growth of the common fish species present in backwater areas of the upper Mississippi River. Some of these questions have been more adequately answered than others .

1 . Estimates of total fish populations of three upper Mississippi River backwater areas, area A and area B near Fountain City, and Miller Lake near La Crosse, Wisconsin, were obtained between 1947 and 1952 by application of a fish toxicant . Standing crops in one of these areas were determined in 4 different years.

2. Standing crops of fish in the six indi- vidual estimates ranged from 39.1 to 604.9 jxjunds per acre and averaged 248.4 founds per acre. Deletion of the weight contributed by adult gizzard shad present in only one of the collections reduced the average weight per acre to approximately 225 pounds . This figure is considered to be more indicative of the average population .

3. Standing crops in the backwater treated on four occasions (area B) ranged from 202.4

to 604 .9 pounds per acre and averaged 324 .2

11/ Personal communication.

46

Table 35: — Species cximposition of fish recovered from a previously dry rearing pond at the U. S. Fishery Station, Guttenberg, Iowa, after recession of high water. May 8, 1951 — expressed as total numbers and weights and as pounds per acre.

	Number		Weight
Species	Total number of pounds	Pounds per acre	Percentage of total weight
Predators Bowf in Shortnose gar	106 26	298.0 26.0	29.8 2.6
Game fish Largeraouth bass . . . Northern pike Sauger	132 23 3 1 3	32i4.0 16.0 1.0 0.5 1.0	32. a 1.6 0.1 0.05 0.1	26.1
Walleye
Panfish White bass Bluegill	30 2 28 1514 21	18.5 0.7 5.0 I4O.0 3.0	1.85 0.07 0.5 I4.0 0.3	1.5
Black crappie Yellow perch
Catfish Black bullhead ....	205 81	148.7 19.0	14.87 1.9	3.9
Forage fish Golden shiner	81 26	19.0 I4.0	1.9 0.I4	1.5
Rough fish Buffalo^/ Carp ,../•. Garpsuckeri' Spotted sucker ....	26 63 170 22 3	I4.C 269.0 5a5.o 9.0 3.0	0.I4 26.9 5a. 5 0.9 0.3	0.3
GRAiro TOTAL	258 732	826.0 1,2140.2	82.6 12a. 0	66.6

1/ Species not shown in original data.

47

Table 36: --Catch of gill nets-'^ lifted within and 50 feet outside of Area B on July 17-18, 19148.

Species Number Size range (inches)

Largemouth bass 1 7.2

Sauger 1 12.2

Black crappie 3 5.14 - 5.7

White crappie 2 6.3 - 12. Ij

fJhite bass 2 8.6-9.0

Channel catfish 2 12.3-13.3

Moone/e 1 10 . 3

Carp 10 11.6-13.2

Spotted sucker 1 17.0

Northern redJ-iorse I4 10.1 - I8.8

1/ One 2-inch bar mesh and one Li-inch bar mesh net lifted on 2 consecutive days.

Table 37: — ia-cer-lavel readings at Fountain City, .Wisconsin for 5 days prior to, and for the dates of, eradication of fish in area B in I9I48, 19li9, 1951, and 1952.1/

Days i9|j8 19i49 I55I 1952 orioi' to

Doi.soning 7 a.m. 6 p.n, 7 a.ii. 6 v.m. 7 a.m. 6 p.m. 7 a.m. 6 p.m.

5 650.72 650.65 650.15 650.33 650.51 65o.)4l 61,9.714 6I49.66

ij

3

2

1

0

50.614	50.6I4	50.03	149.72	50.35	50.1^2	I49.58	I49.55
50.62	50.62	I49.95	I49.32	50.29	50.18	lj9.68	I49.72
50.62	50.62	50.35	I49.55	50.03	I49.90	I49.8I	149.38
50.61	50.63	I49.69	1j9.70	I49.7I4	h9.9S	1j9.83	149.35
50.65		I49.65		50.18		I49.90

1/ Liata pro/ided by the U. S. Corps of Engineers, St. Paul District.

48

pounds per acre. Deletion of the adult gizzard shad reduced the average weight per acre to approximately 285 pounds. This figure also is considered to be more indicative of the average population of area B.

4. To facilitate evaluation of the popu- lation data the various spyecies were arranged in the following groups: predators, game fish, panfish, catfish, forage fish, and rough fish.

black crappie, white crappie; 4) catfish -- channel catfish; 5) forage fish -- gizzard shad; and 6) rough fish -- carp, spotted sucker, and freshwater drum.

11 . Weight composition by species groups in area B varied greatly from year to year. The most stable comp)onent of the populations was the catfish group while the rough fish group was the most variable.

5 . On the basis of adjusted average weight per acre of 285 pounds, the mean percentage composition of the various species groups in area B was predators, 27; game fish, 12; panfish, 13; catfish, 11; forage fish, 1; and rough fish, 38. On the same basis, average composition in pounds per acre was: predators, 77; game fish, 29; panfish, 36; catfish, 30; forage fish, 2; and rough fish, 112.

6 . Average standing crops of the three northern backwaters and of area B alone were less than the mean weight per acre of four backwater areas in the southern section of the river but the predator and game fish components were greater in the upper section.

7 . The average standing crop of areas A and B and Miller Lake exceeded that of inland waters to the north, approximated that of waters in the same general latitude, and was less than the mean crop of inland waters to the south.

8. The preponderance of species with long food chains suggests that total standing crops with the existing species composition are comparatively high for the latitude.

9. Production of game fish in area B tended to exceed that in most waters of the north-central States where comparison was made. Weight per acre of panfish in the same area tended to approximate that in northern inland waters but was much less than that in waters to the south.

10. The most prominent species in the backwaters in each of the species groups were: 1) predators -- bowfin; 2) game fish -- northern pike and largemouth bass; 3) panfish -- bluegill.

12. Very few fish over 5 years of age were found in the four collections from which fish were aged. The great majority of game fish and panfish were less than 3 years old.

13. Growth rates of most species were faster than those of the same species in almost all waters of the north-central States where a comparison was made, including the Illinois - Missouri section of the river.

14 . Results of water analyses indicated that chemical fertility of the upper Mississippi River is high when comf)ared to that of other waters producing heavy crops of fish .

15 . Bottom soils of the backwater areas have a higher organic content (7.49 percent) than those of adjacent running channels (2.64 percent) and also a finer texture.

16. CompKDSition of the bottom fauna in the backwaters of the upper Mississippi River has changed since the navigational locks and dams were installed but production per unit area com- pares favorably with that observed before installation of those structures.

17. Differences in standing crops in area B during the 4 years could not be related to changes in water level .

ACKNOWLEDGMENTS

The authors appreciate Dr. Raymond E. Johnson's assistance in detailed identification of fish and in field work. Dr. John Greenbank's supervision of much of the early general field work. Dr. John B. Moyle's identification of aquatic plants, and to Mr. John Dobie's cooperation

49

in running bottom soil and water analyses . Appreciation is also tendered to Mr. Glenn Voskuil who assisted in preparation of the illustrations, and to other personnel who as- sisted in the field work.

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50

18. Erlckson, James G.

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51

34a. Moyle, John B., Jerome H. Kuehn, and Charles R. Burrows. 1950. Fish population and catch data. Transactions American Fisheries Society, Vol. 78(1948), pp. 163-175.

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52

51. Speaker, E. B.

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Wood, Roy. 1951 . The significance of managed water levels in developing the fisheries of large impoundments. Journal, Tennessee Academy of Sciences, Vol. 26, No. 3, pp. 214-235.

53

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