BULLETIN No. 274JUE95 JUNE 1950 RE LATIONSHIPS and DYNAMICS of BALANCED and UNBALANC POPULATIONS FORTH t, V SIENCE FD + r ADVANCEMENT C ~ XV ( ., ND ARTS STATION AGRICULTURAL EXPERIMENT oj~ie ALABAMA POLYTECHNIC INSTITUTE M. J. FUNCHESS, Director AUBURN, ALABAMA CONTENTS Page INTRODUCTION --------------------------------------------- 3 BALANCED AND UNBALANCED POPULATIONS----------------------------6 INTERRELATIONS BETWEEN GROUPS IN BALANCED AND UNBALANCED POPULATIONS __------_-------------- 8 THE F/CGRTIO------------------------------------------------THE TIIEAT 8 16 20 Y/ CRATIO VALUE ------------------------------------------------------------ ----- --- ------------ ----------------------- E VALUES -------------------------------------------------------------------- 25 27 RELATIONSHIPS WIHN SPECIES -------------------------------------------- A, I,and Svalues --------------------------------------------------- 27 CHANGES DUE TO RATES OF HARVEST IN BALANCED POPULATIONS ------------- _------8------------------ 7 SUMM ARY ----------------------------------------------- 40 LITERATURE-- ------------------------------------------------- 48 APPENDIX --------------------------------------------------------------------------- 45 FIRST PRINTING IOM RELATIONSHIPS and DYNAMICS of BALANCED and UNBALANCED FISH POPULATIONS H. S. SWINGLE, Fish Culturist is being given in fisheries research to the determination of composition of fish populations in both natural and impounded waters in attempts to evaluate their condition and to devise more effective methods of management. There are various techniques available for use in determination of populations in various types of habitats, and improvements in these methods are being devised yearly. Draining of ponds and subsequent counting and weighing of the entire fish population (21) obviously give the most accurate records, but this method is unusable in natural waters and in most impounded waters. Haskell (7) described a technique of using electrical shock to sample populations in streams. The inactivated fish were collected, measured, weighed, and returned to the stream where they rapidly recovered. This method is being widely used for survey of small streams, but it apparently is largely valuable for censusing the adult fish while the young are inadequately recovered or reported. Embody (4) reported success in using cresol at concentrations of 1 part to 30,000 parts of water in flowing streams for census work. The fish were rendered temporarily inactive and subsequently recovered upon being returned to the stream. This method is rarely used because more effective methods are now available. Estimation of populations by the marking and recovery method has been investigated by a number of workers, including Shumacher and Eschmeyer (14), Krumholz (10), and others. It is useful mainly in estimating the adult fish in a population and is employed mainly where more accurate methods cannot be used. Smith (16) used copper sulphate at a concentration of 8 p.p.m. to kill and census the populations of fishes in acid Nova Scotian lakes. This material was found to retain its toxicity to plankton and insects in the deeper waters for one year or more. As a consequence, it is now seldom, if ever, used for censusing populations. Eschmeyer (5) and Thompson and Bennett (25) followed by numerous other workers employed powdered derris root for the purpose of NCREASING ATTENTION I 4 ALABAMA AGRICULTURAL EXPERIMENT STATION killing and censusing fish populations. The use of derris root or other rotenone-containing plant products and extractions is the most satisfactory and useful of the various methods of population sampling in most natural waters and large impoundments. Historical accounts of the development of the various uses of rotenone are given by Krumholz (11) and Solman (19). Tarzwell (24) compared the results of population studies from records obtained by rotenone poisoning, gill nets, set lines, seining, hoop nets, and sport fishing records. Poisoning with rotenone yielded the most complete population records, the other methods being highly selective for certain species within the population. Determination of populations by rotenone poisoning has been shown by various workers to have certain inaccuracies. Thompson and Bennett (25) gave records showing that poisoned fish continued to come to the pond surface for 4 days following poisoning. Failure to pick up poisoned fish over an extended period, therefore, would give incomplete population records. Brown and Ball (3) reported that unknown numbers of small fish did not come to the surface and were not recovered or included in their population figures. It would appear that in censusing most populations by rotenone poisonings, little attempt has been made to include complete records of the small fish. This is a very serious defect in the method. Recovery of even the large fish following poisoning is apparently incomplete. Krumholz (10) reported recovery of 86 per cent of previously-marked fish and Ball (1) reported recovery of only 58.9 per cent of marked bluegills and 44.7 per cent of marked trout. Apparently the unrecovered fish decayed on the pond bottom without bloating, or were entangled in weed growths in deep water. It is apparent that additional investigations relating to completeness of recovery of both the adult and small fish in poisoned populations under various conditions are necessary. Nevertheless, censusing or sampling populations by rotenone poisoning is still the most effective and accurate method available for most natural waters and many impoundments. The foregoing techniques for censusing populations are being used to an increasing extent each year. There is, however, no uniformity in the methods of presenting or interpreting the information obtained because of a lack of standards for comparison of various populations. Smith (16) counted and weighed samples of dead fish on measured areas of shore-line and reported his results as the numbers and weights of each species per acre. Thompson and Bennett (25) reported the numbers, weights, and average weights of each species and the length-frequencies of more important species. They divided the species into groups of largemouth bass, "other fine fish," catfish, "rough fish," BALANCED and UNBALANCED FISH POPULATIONS 5 and "forage fish" and reported the percentage of the total weight that each group comprised. Bennett (2) in his summary of the populations in 22 Illinois ponds, reported each species and its percentage of the total weight in each population. O'Donnell (13) reported the numbers and weights of adult and fingerling fishes of each species and their length-frequencies. Eschmeyer (6) divided some species into length groups and reported the numbers and weights in each group. He also reported the number of fish small enough for bass to eat. Brown and Ball (3) reported the ages, sizes, numbers, weights, and percentages of the total weight of the population for each species. They also classified the fish into groups of "game fishes" and "legal game fishes." Tarzwell (24) listed each species with their corresponding percentages of the total weights and of the total numbers of the populations. He grouped the species under "game fish," "coarse fish," "pan fish," and "food fish" and computed their percentages of the total population weight. Swingle and Smith (22) grouped the various species into "forage fish (F)" and "carnivorous fish (C)." They reported F/C ratios of 1.9 to 3.5 in old ponds and suggested the use of a F/C ratio = 2 in determining the number of fish required for stocking new ponds. Meehean (12) from poisoned populations in Florida lakes reported ratios of "predators to supporting population" of 2.27 to 3.16. In his predator group, he included piscivorous fish plus turtles. From the foregoing discussion, it is evident that the fisheries technician can now, with the various methods at his disposal, determine more or less accurately the species composition of a particular population. He appears, however, somewhat at a loss as to just what to do with this information, how it should be reported, and how to interpret it. It must also be kept in mind that the data he reports are more or less static figures representative of that particular population only at that instant or period of time when the census was made. The live population, however, was not static, but dynamic - constantly changing in individuals and in relative composition due to growth, predation, removal, mortality, and reproduction. Consequently, it is not enough to merely know the species present and their relative percentages of the total population. The interrelationships between species, between groups of species and between groups within species, and the dynamics of their relationships in fish populations must be understood if fisheries biologists are to manage effectively fisheries resources. In the experimental work on pond management at the Alabama Agricultural Experiment Station during the past 15 years, the compositions of 89 separate well-established fish populations from 2 years to 30 years old have been determined. The population censuses were determined, except for four ponds poisoned by rotenone, by draining 6 ALABAMA AGRICULTURAL EXPERIMENT STATION ponds and counting, sorting, and weighing the fish. This insured relatively accurate data on the composition of each population. Various relationships within species, between species, and between groups of species in these populations were determined and compared with their ability to yield satisfactory annual crops of fish. The dynamics of certain interrelationships were determined by periodic determination of changes in selected populations over a period of several years and by experiments with various stocking procedures. It is believed that certain of these relationships will prove of value as standards for comparison of various fish populations. BALANCED and UNBALANCED POPULATIONS The interrelationships in fish populations are satisfactory if the populations yield, year after year, crops of harvestable fish that are satisfactory in amount when the basic fertilities of the bodies of wafer containing these populations are considered. Such populations are considered to be "balanced populations" and the species within such a population are "in balance." In order to produce annual crops of harvestable fish, it is evident that the species within a balanced population must be able to reproduce periodically, usually at least annually, in order to replace the harvested individuals. Ability to reproduce within the environment, therefore, must be one criterion of a balanced population. Due to high reproductive capacity of fishes, the ability to reproduce within a population usually results in greater numbers of individuals than can be grown to a desirable size for harvesting. To produce annual harvestable crops, the number of young fish must be controlled by predatory species (22). Balance in populations, therefore, implies a combination of species, including at least one piscivorous (carnivorous) species. Balance then denotes a condition within a population such that if 100 pounds of fish are harvested one year the correct numbers of replacements will be provided from the population so that a satisfactory poundage of fish of desirable size may be harvested in succeeding years. If the population provides too many replacements, these fish will not reach a satisfactory size for harvesting; conversely, if too few replacements are provided, the capacity of the body of water to produce will not be fully utilized and the harvestable poundage will seriously decline. The delicacy of the balance involved may be illustrated by the results in a simple bluegill-bass combination. Where bluegills are BALANCED and UNBALANCED FISH POPULATIONS 7 stocked in a fertilized pond at the rate of 1,500 per acre, approximately 1,000 will survive to reach a harvestable size of 4 ounces within 1 year and will completely utilize the food available for large bluegills. Each pair of bluegills then produces an average of 5,000 young during the first summer. In successive years, 4-ounce bluegills can be caught only if the young fish are reduced by predation and natural deaths to approximately the number removed by fishing plus the number of old fish that die annually. In that case, if both the adult parents are lost from these combined causes, there is room in the pond for two replacements to grow to a 4-ounce size; the predatory fish and natural mortality must, therefore, remove 4,998 and leave 2 replacements in this family group. Actually, for various species in various aquatic environments and for different rates of harvest, from 1 to 5 or more years will be required for the reduction in numbers of a brood to the correct number of replacements for the adult fishes lost from these combined causes. This gives rise to the various "year classes" and "length-frequency" groups below the size of the harvestable fish in a population. These smaller fishes have two primary functions in a population. They serve as food for the piscivorous species and furnish replacements for the adult stock. Consequently, from a functional standpoint, a species or a population may be said to be composed of three groups: the adult fish, or size satisfactory for harvesting; the intermediate fish or primary replacements that are too small for harvesting and too large to serve as food for the average-sized adults of the predatory species; and the small fish that are of such size that they may be eaten readily by the predatory species. Considerable variations in total poundages harvestable occur normally in balanced populations from year to year due to the relative efficiencies with which populations supply the required numbers of replacements. Even greater variation may occur in the annual harvestable poundage of a single species in a balanced population of many species due to competition between species for a common food supply. This may cause a decrease in the total weight of one species corresponding to an increase in weight of a competing species. If this shift is to an unharvested or undesirable species, the total weight harvested from the population will show a corresponding decrease. Unbalanced populations are those unable to produce succeeding annual crops of harvestable fish. This may be due to the inefficiency of the component species in such a combination - that is, their inability to provide sufficient replacement individuals to maintain satisfactory utilization of the potential food supply. It is more commonly due to overcrowding - the survival of so many individuals that none can grow to a size satisfactory for harvesting. 8 ALABAMA AGRICULTURAL EXPERIMENT STATION INTERRELATIONS BETWEEN GROUPS in BALANCED and UNBALANCED POPULATIONS The separate compositions in numbers and weights of each species in 55 balanced (Appendix Tables 1-B to 55-B) and 84 unbalanced populations (Appendix Tables 1-U to 34-U) are given in the Appendix. Various relationships between species and groups of species and within species were computed for these populations in an attempt to discover those of most value in differentiating balanced and unbalanced populations and to evaluate the relative efficiencies of the various species and combinations. These various relationships, the methods for their computation, their significance, optimum values, ranges, and dynamics in balanced and unbalanced populations will be discussed in the following pages. THE F/C RATIO DEFINITION. This is the ratio of the total weight of all forage fishes to the total weight of all carnivorous (piscivorous) fishes in a population. "F" AND "C" SPECIES. The carnivorous, or piscivorous, (C) species of fishes are defined as those that feed principally upon other and smaller fishes, and that cannot grow to normal average sizes of adults of those species without such food. All other fishes in a population are grouped together as forage (F) species. The "F" species feed largely upon plants, plankton, crustacea, and insects, but may occasionally eat small fish. The largemouth black bass, Micropterus salmoides (Lacepede), is the principal "C" species used in pond-fish culture. Although this fish feeds to a certain extent throughout life upon insects, it seldom is able to reach a size in excess of 0.3 pound upon such a diet. To reach the normal adult size, small fish must be available for food. Even very small bass prefer the fish diet and are found feeding upon it whenever it is available. Consequently, all sizes of largemouth bass are grouped as "C" fishes. The crappies, Pomoxis annularis Rafinesque, and P. nigro-maculatus (LeSueur), have been found in experiments to belong to either "C" or "F" groups, depending upon their sizes. Crappies up to 4 ounces in weight fed largely upon insects and competed directly with bluegills for food. They apparently, however, were unable to grow to a larger size without small fishes for food and those above 4 ounces in weight competed directly with largemouth bass. Consequently, the total weight of all crappie up to and including 4 ounces was included BALANCED and UNBALANCED FISH POPULATIONS 9 in the "F" group and the weight of all larger individuals in the "C" group. All sizes of pickerel, Esox niger LeSueur; gar, Lepisosteus osseus Rafinesque; spotted bass, Micropterus punctulatus Rafinesque; and bowfin, Amia calva Linnaeus, are classed in the "C" group. All sizes of bullheads Ameiurus; the channel catfish, Ictalurus lacustris punctatus (Walbaum), up to a size of 2 pounds; the blue cats, I. furcatus (Valenciennes), up to a size of 8 pounds; and the flathead cat, Pilodictis olivaris (Rafinesque), up to a size of 8 pounds were found in experiments to compete with bluegills and not with bass. Consequently they were all placed in the "F" group. It is quite possible that very large channels, blues, and flatheads may belong in the "C" group, but information is lacking to justify this shift in classification. It would appear improbable that a 30-pound flathead cat could support itself without resort in large measure to a fish diet. Due to its sluggish nature, it would also appear doubtful that it could capture many active fish. However, in unfished fish populations, up to 25 per cent or more of the fishes die yearly and it is possible that these dead or dying fishes form a considerable portion of the food for large flatheads and other large cats. The principal other species in the "F" group present in natural and impounded waters reported in this investigation were bluegills, Lepomis macrochirus Rafinesque; stump knockers, L. punctatus Jordan; shellcrackers or red-ears, L. microlophus (Gunther); green sunfish, L. cyanellus Rafinesque; long-eared sunfish, L. megalotis Rafinesque; orange spotted sunfish, L. humilis (Girard); warmouth, Chaenobryttus coronarius (Bartram); yellow bullhead, Ameiurus natalis (LeSueur); speckled bullhead, A. nebulosis marmoratus (LeSueur); golden shiner, Notemigonus crysoleucas (Rafinesque); chub suckers, Erimyzon sucetta (Girard); gizzard shad, Dorosoma cepedianum (LeSueur); goldfish, Carassius auratus (Linnaeus); gambusia, Gambusia affinis (B. & G.); buffalo, Ictiobus bubalus (Rafinesque); spotted sucker, Minytrema melanops (Rafinesque); carp, Cyprinus carpio Linnaeus; and eel, Anguilla bostoniensis (LeSueur). CALCULATION OF F/C RATIOs. To illustrate the calculation the following population is given: Pounds ________ 43 large largemouth bass __2.8 ------68 small largemouth bass -------41 large black crappie_. 4,196 intermediate black crappie ___-----275.4 53.9 12.6 4.7 818 small black crappie _-----_-57.8 _ 724 intermediate bluegills 18,860 small bluegills Total - 219.0 626.2 10 ALABAMA AGRICULTURAL EXPERIMENT STATION The weight of "F" species, or the "F value," equals the weight of all bluegills plus the weight of small plus intermediate black crappie: 219.0 + 57.8 + 4.7 + 275.4 = 556.9 pounds; while the weight of "C" species, or the "C value," equals the weight of all bass plus the weight of all crappie weighing more than 4 ounces: 53.9 + 2.8 + 12.6 = 69.8 pounds. The F/C ratio in the above population was, therefore: F value F/C =8.0 C value 556.9 69.8 8.0 1.0 It is quite obvious that this isolated F/C ratio is of little value until those in other known populations are available for comparison. Here it merely indicates that the predatory "C" species made up one-ninth of the total weight of the population. The F/C ratios in the balanced and unbalanced populations given in the Appendix were computed in the manner indicated above, and their frequency distributions are given in Figure 1. Number 16 14 8 Balanced Populations 0! 2 3 4 5 6 7 8 9o101I12 13 14 15 16 60 62 64 6 8 Unbalanced Populations FIGURE 1. Frequency distribution of F/C ratios in balanced and unbalanced populations. BALANCED and UNBALANCED FISH POPULATIONS II VALUES OF THE RATIO IN BALANCED AND UNBALANCED POPULATIONS. In the balanced populations, the range in F/C ratios was from 1.4 to 10.0, and 94.3 per cent were within the range of 1.4 to 6.8. In contrast to these rather tightly grouped F/C values, the corresponding range was from 0.06 to 65.1 in the unbalanced populations. In the balanced populations, all F/C ratios were not equally desirable. Within the range 1.4 to 2.0, there occurred only populations in which bass were overcrowded, or from which no bass had been harvested over a period of 2 years, or in which a large golden shiner population had been largely eliminated by the "C" species during the summer preceding draining. Within the range F/C = 2.0 to 3.0, approximately 50 per cent of the populations were somewhat overcrowded by the "C" species. In this range also was found a population (Table 44-B) where following 8 years of fertilization no fertilizer was applied for 1 year prior to draining. As is usual in such cases, reduction in fertility reduced production of the "F" species more rapidly than it affected the "C" species. Reduction in food prevented the movement from the group of small fishes into the intermediate group and the movement of the intermediates into the group of large fishes, thus subjecting them to predation for a longer than normal period of time. This combined with the harvesting of adult "F" species has tended to produce low F/C ratios in fish populations when fertilization has been discontinued. The F/C ratios from 3.0 to 6.0 appear to be the most desirable in the balanced range, and 77 per cent of the best producing populations fell within this group. However, 66 per cent of the poorest of the balanced ponds also was in the same range. It is, therefore, apparent that other relationships within a population, in addition to the F/C ratio, must be known in order to adequately describe the capacity of a population to produce yearly crops of harvestable fish. It is also evident in Figure 1 that the F/C ratios for balanced and unbalanced ponds overlapped to a considerable extent. However, in the range from F/C = 0.06 to 2.7, all unbalanced populations (Tables 12-U, 17-U, and 21-U) were unbalanced because the F species (green sunfish or shellcrackers) were disappearing under bass predation. Also, all populations with F/C ratios in excess of 10 were unbalanced. There was, in addition, a noticeable difference in the modes of the two types of populations; in balanced populations ratios between F/C -= 8 to 4 occurred most frequently, while in unbalanced populations the peak occurred in the interval F/C = 7 to 8. It would appear, therefore, that, in fish populations capable of producing yearly crops of harvestable fish, there is a relatively narrow range in the ratio of the weight of F species to the weight of C species. In effect, the weight of F species present would appear to be a func- 12 ALABAMA AGRICULTURAL EXPERIMENT STATION tion primarily of the fertility of the body of water in which it exists; the weight of C species, within limits, is apparently dependent in turn upon the weight of the "F" species upon which it is dependent for food. Values between F/C = 1 to 8 apparently indicated, in general, populations somewhat overcrowded with "C" species. This is an undesirable condition because overcrowded C species eventually result in reduced total production, as indicated by the following results of three experiments on rates of stocking bass (Table 1). TABLE 1. EFFECT OF RATES OF STOCKING LARGEMOUTH BASS ON FISH PRODUCTION Rates of stocking per acre 1-year experiment 2-year experiments Total lb. fingerlings 1,500 1,500 1,500 1,500 1,500, Bluegill Bass Total lb. F/C per acre 383.2 871.6 394.4 fish per acre 886.0 808.4 216.2 850.0 224.2 fish F/C 100 Fry 150 200 100 200 Fry Fry Fingerlings Fingerlings 12.8 8.8 5.8 10.0 6.2 2.2 5.5 8.2 1,500 400 Fingerlings 207.0 2.5 These experiments indicate no reduced production at the end of 1 year, but there was a sharp decline in total production and low F/C values resulted during the second year with increased rates of stocking bass. Apparently overcrowded bass allowed the survival of insufficient bluegills to replace the adults lost by natural mortality, and as a result there were insufficient individuals to utilize the food efficiently. STABILITrY OF RATIos. The F/C ratio gives considerable information concerning a population. The problem then arises as to whether it is a fluctuating or a relatively stable value for a particular population over a period of years. In order to answer this question, a 1.3-acre pond was stocked with 1,500 bluegill fingerlings + 100 bass fingerlings + 4 white crappie fingerlings per acre. After 1 year, the pond was drained and the F/C ratio determined. All fish were returned to the water and the pond was fished the subsequent season for both bluegills and bass. At the end of the next year, the pond was again drained, the F/C ratio determined, and the fish returned to the pond. It was again fished and at the end of the third year it was drained and the experiment terminated. The results were as follows: BALANCED and UNBALANCED FISH POPULATIONS 13 F/C ratios in population Age of population F/C Ratios years First in catch - on draining in December 5.1 Second Third 2.0 5.7 4.6 4.7 Since it appeared possible that draining annually may have upset the natural balance and resulted in abnormal values, it was decided to restock the same pond with 1,500 bluegill fingerlings 100 bass fingerlings, fish annually for 4 years, and then drain and determine the F/C value of the population. These results were as follows. d- Age of population years First F/C Ratios in catch 2.8 F/C Ratio in population on draining in December -- Second Third Fourth 2.9 3.2 1.8 4.4 It is apparent that in these experiments, where the fertility remained relatively constant due to uniform fertilization and the cover remained constant, the F/C ratios in the populations remained relatively constant in spite of great variations in the ratios between harvested F and C species. It must be remembered that the F/C ratio is a ratio between weights and not between numbers of fishes. With the harvest of 10 pounds of F or C species, food is released that enables the remaining individuals in these groups to increase their total weight by a similar poundage. It would appear necessary for the ratio to change immediately following a heavy withdrawal from the population, but indications are that it will tend to approach closely the original value within an indefinite subsequent period. Insufficient experiments are available to determine the effect of time, cover, relative areas of shallow and deep waters, and other possible factors upon the F/C ratios in fish populations. The effect of age of a population upon the F/C ratio is especially worthy of further investigation. In numerous experiments, it was found that populations seldom reached a relatively stable F/C ratio until the "C" species had been in the pond for approximately 1 year and had reproduced. Possibly further changes with age may occur under certain conditions. One pond, stocked with 1,500 bluegills + 100 bass per acre, had a F/C ratio = 4.5 at the end of 6 years. In ponds with unknown rates of stocking, one had a F/C ratio = 3.2 when 9 years old; one a F/C ratio = 2.2 when 13 years old; one a F/C ratio - 5.1 when 25 years old; one a F/C ratio = 2.7 when 25 years old; and another, a F/C ratio = 2.2 when 30 years old. The majority of 14 ALABAMA AGRICULTURAL EXPERIMENT STATION these older ponds, therefore, had low F/C ratios in the range where populations are inefficient and had been drained or poisoned because they were giving unsatisfactory fishing. If there were a shift with age of balanced populations toward a F/C ratio of 2.0 or lower, this might in part explain the decrease in catch correlated with increase in age of many inpoundments that contain only desirable sport fishes. However, the low F/C values reported for these old ponds may be the result of the unknown methods of stocking or other factors and not the result of age. Meehean (12) reported ratios of "predators to supporting population" in poisoned Florida lakes to range from 2.27 to 3.16. This would appear at first glance to indicate F/C ratios of low values. However, turtles were included in the "predator population," while the F/C ratio is confined to the weights of various species of fishes. The calculated F/C ratios for these fish populations were 4.0, 5.8, 6.0, 3.3, and 6.4. His results, therefore, do not show low F/C ratios in old populations. The computed F/C ratio of the fish population in Michigan's Third Sister Lake reported by Brown and Ball (3) was 5.3, also a relatively high value. The presence or absence of heavy cover, and the relative areas of extremely shallow water influence the efficiency of predation and may be expected to influence the F/C ratios in various bodies of water. No information regarding these problems is available. USES OF F/C RATIO. A knowledge of the distribution of F/C ratios for entire populations under various conditions of balance and unbalance provides standards for comparison and analysis of samples from various other populations. Since this adds to the understanding of the condition of a population, it should also aid in the determination of correct management practices. Conditions in populations indicated by various F/C ratios are summarized in Figure 2. Overcrowded C species I4 I Range inbalanced populations kMost desirable range I i F/c ,, 006 O 1.0 2.0 2.7, 3.0 4.0 5.0 6.0 , 7.0 8.0 groups 9.0 - 10.0 -65.0 -- F Species disap- Overcrowded IF and/or SF pearing under predation All populations Range in unbalanced populations unbalanced FIGURE 2. Conditions in populations indicated by F/C ratios. BALANCED and UNBALANCED FISH POPULATIONS 15 Use of the F/C ratio for determination of methods for stocking new waters has been suggested previously (22). Because of the lack of sufficient information, a F/C ratio of 2 was arbitrarily accepted and only 50 per cent of the calculated number of bass was used in stocking. Additional information in this report allows the use of more accurate F/C values, and information from other experiments on annual mortality of bass allows a more accurate estimate of the rate of stocking of new waters for production of balanced populations where the approximate carrying capacity in pounds of fish per acre is known. Where this is not known, it can be determined by poisoning and weighing established populations or by stocking new waters with 1,000 or more bluegills only per acre and determining the total production per acre at the end of one year. If it is found that ponds in a certain area will support 100 pounds of bluegills or similar fish per acre, the number of bluegills and bass required for stocking may be figured as follows: A F/C ratio = 4 is in the desirable range. If this ratio is achieved, the weight of bluegills in a balanced bluegill-bass population in the above pond after 1 year will be: 4/5 x 100 = 80 pounds Since bluegills will reach a size of 4 ounces in one year, the number required for stocking to give the above weight one year later is: 80 x 4 - 320 bluegills Actually, only 75 per cent of the bluegills used in stocking, will, on the average, be alive one year later. No correction for this mortality is necessary in the case of bluegills, because they will spawn during the first summer and the loss due to mortality is replaced by the weight of young fish. Similarly, the weight of largemouth bass in the above population after 1 year will be: 1/5 x 100 = 20 pounds Since largemouth bass will reach a size of 1 pound in one year, the number of calculated bass required is: 20 x 1 = 20 bass However, it has been found that on an average only 70 per cent of the bass used in stocking will be alive one year later, and no young will be produced normally until the second summer. Consequently, it is necessary to stock such a number that 20 bass may be expected to be alive when the pond is one year old, or: 70% = 20 bass 100 100%= 70 x 20 = 29 advanced fry or fingerling bass should be added. 16 ALABAMA AGRICULTURAL EXPERIMENT STATION If the pond will support 400 pounds of fish per acre, the number of bluegill fingerlings desirable for stocking to achieve a F/C ratio = 4 will be: 4/5 x 400 = 320 pounds 820 x 4 = 1,280 bluegill fingerlings The number of bass will be: 1/5 x 400 = 80 pounds of bass or 80 1-pound bass 70% = 80 bass 100 80 = 114 advanced fry or fingerlings. 100% =70 If the above numbers of each species are used, balanced populations will usually result, barring excessive mortality among the stocked fish. THE Y/C RATIO DEFINITION. The Y/C ratio equals the Y value, or the total weight in pounds of all those individuals in the "F" group that are small enough to be eaten by the average-sized adult in the "C" group, divided by the C value, or total weight in pounds of the "C" group. In other words, it is the pounds of small fish of the "F" species available as food for each pound of "C" species in a population. CALCULATION OF Y/C RATIOS. For the populations given in the Appendix, each "F" species was divided into groups of small, intermediate, and large fishes at the time the population was being sorted and weighed. The group of "small" fish included all small fish of a species up to the maximum size that could be swallowed readily by the average-sized "C" fishes in the "large" groups. The Y/C ratio then equaled: Y Value C Value Total pounds of all "small" fishes in the "F" group Total pounds of "C" species In a population with the following composition: 48 large largemouth bass 68 41 4,196 818 small largemouth bass large black crappie intermediate black crappie small black crappie -- -- Pounds 53.9 _- _- 724 intermediate bluegills 18,860 small bluegills Tta1I i ve~-\ ~-\ ;A I ~V !l o - ----- 2.8 12.6 275.4 4.7 57.8 219.0 626.2 ~- ~- BALANCED and UNBALANCED FISH POPULATIONS 17 Y = 4.7 pounds small black crappie + 219.0 pounds small bluegills = 223.7 pounds C = 53.9 pounds large bass + 2.8 pounds small bass + 12.6 pounds large crappie = 69.8 pounds Therefore, Y/C = 223.7 69.83 REASONS FOR ITS CALCULATION. It has been shown that there is a relationship between total weights of forage and carnivorous species in a population. However, only that portion of the total "F" weight that exists in small enough units to be gulped by the "C" species is actually available as food for the latter. It would appear that the Y/C ratio should express the condition within a population affecting the growth of the "C" species and might be useful as a measure of balance. At least, a knowledge of its limits in balanced and unbalanced populations should add to an understanding of population composition and dynamics. Unfortunately, the Y/C ratio could only be determined as a static value - true for the population at the time at which draining or poisoning occurred. = 8.2 Y/C RATIOS IN BALANCED AND UNBALANCED POPULATIONS. The Y/C ratios for the populations given in the Appendix were calculated; their frequencies of occurence in balanced and unbalanced populations are shown in Figue 3. The range of these values was relatively narrow in balanced populations - from 0.02 to 4.8. Within the range 0.02 to 0.5, all populations were so severely overcrowded with "C" species that they probably should be considered "temporarily balanced" because the bass were unable to gain weight and in fact will lose weight, while insufficient numbers of bluegills were surviving to adequately utilize available food. Consequently, populations with these values were inefficient. In the range 0.5 to 0.9, the "C" species apparently lacked sufficient food for good growth. The most desirable range appeared to be 1.0 to 3.0. Above 8.0, the small fishes apparently reduced the average sizes of the large forage fishes. All populations with Y/C ratios in excess of 4.8 were unbalanced and were incapable of producing yearly crops of harvestable fish. These populations were composed largely of overcrowded forage fishes. It will be noted also that some unbalanced populations had Y/C ratios overlapping in range with those in balanced populations. In the range 0.06 to 8.0, occurred populations unbalanced because the "F" species (green sunfish, Tables 12-U and 21-U, or shellcrackers, 18 ALABAMA AGRICULTURAL EXPERIMENT STATION 18L AL~BMA AGRBICUTRLEPRMNTTO Number 22 2 18 66 s: 14 a :: 12 . iI is Balanced Populations 6 t.111 '.1.1 7 i 8 9 1' t 10 t 1121314 i 15 16 6 Unbalanced Populations 8 FIGURE 3. Frequency distribution of Y/C ratios in balanced and unbalanced populations. Table 17-U) were disappearing under predation, or those unbalanced because of the accumulation of large weights of stunted fishes in the "intermediate" groups as a result of insufficient predation. USES of RATIO. In the range of Y/C ratios above 5.0, the Y/C ratio alone is sufficient to indicate the extent of unbalance. However, in the lower ranges it is apparent that other factors in addition to the Y/C ratios must be known in order to differentiate balanced from unbalanced populations. However, the Y/C ratio is very useful in determining the desirability of the balance within a population and in indicating future trends in species interrelationships. .This ratio emphasizes the importance of small fishes in those populations that are capable of producing yearly crops of harvestable fish. In populations censused by poisoning, too little attention has been given to their recovery or their estimation. An estimate of their abundance and the calculation of the Y/C ratio gives information of great value concerning a population. The conditions in populations indicated by various Y/C ratios is summarized in Figure 4. BALANCED and UNBALANCED FISH POPULATIONS 19 Overcrowded C Species Temporary Range in balanced populations Desirable range 2.0 , 3.0 4.0 ,06-All populations unbalanced 5.0 5.O+ Balance 0.02 " 0.5 1.0 oe , F Species disappearing Y= Range in unbalanced populations FIGURE 4. Conditions in populations indicated by Y/C ratios. STABILrrY OF Y/C RATIOS. As has been indicated, the Y/C ratio is an expression of a condition in a population at the time of censusing. The various populations reported in this bulletin were censused in June, July, August, September, October, November, December, or January, the great majority being in the period of September to December. No difference in Y/C ratios appeared correlated to the time at which these records were obtained. However, it would appear that the values for this ratio should be least in the spring just prior to spawning of the "F" species, and should increase subsequent to this period. The ratio also should be affected to some extent by day to day predation and by the rates of harvest of adult fishes. However, since the ratio is a weight ratio, it does not fluctuate as greatly as might be expected. In some populations it was found possible to determine the Y/C ratios each year for 2 to 8 years by draining the ponds and returning the entire population upon refilling. In one pond where no "C" species were removed over a 3-year period, the successive annual Y/C values were 6.9, 8.1, and 1.1. In another pond, where no "C" species were removed for 2 years, the Y/C ratios at the end of each year were 8.5 and 1.9; and, in a similar pond under the same conditions, the Y/C ratio dropped from 1.6 at the end of the first year to 0.7 at the end of the second. In another pond where very light fishing occurred for 2 years with resulting Y/C ratios of 0.8 and 0.6 at the end of each year, heavy fishing the third year for both "F" and "C" species resulted in an increase by the end of that year to Y/C = 2.0 - a much healthier condition in the population. It is evident, therefore, that the Y/C ratio is a dynamic value changing with changes in predation pressure and varying rates of harvest, yet remaining within a rather narrow range in balanced populations. Since it is a constant within limits, each rise in pounds of 20 ALABAMA AGRICULTURAL EXPERIMENT STATION 20 ALABAMA AGRICUTRLEPRMN TTO small fishes must be accompanied by a subsequent corresponding rise in pounds of "C" species or the population is not balanced. As the degreesof success of many natural waters and large impoundments are judged solely by their ability to produce "C" species, the Y/C value and the factors affecting the value of Y are of utmost importance in management. The latter will be discussed further in a subsequent section. Tim AT VALUE DEFINITION. The AT value (total availability value) is the percentage of the total weight of a fish population composed of fish of harvestable size. HARVESTABLE SIzE. In order to calculate the available yield from a population, it is necessary to set standards of the minimum sizes suitable for harvest. For certain fishes in certain areas, these sizes are set by law. However, they vary from place to place and from year to year and are usually given as length limits that are unusable for population studies. Consequently, minimum weights for harvestable fishes of the species used in these studies were adopted as follows: Pounds Bluegills, shelicrackers and similar sunfishes ------------------ 0.1 Crappies---------------------------------------------------------0.26 Largemouth bass-------------------------------------- 0.4 Bullheads------------------------------------0.8 Gar ------------------------------------------------1.0 Buffalo-----------------------------------------1.0 Ca----------------------------1.0 Gizzard shad------------------------------------------0.5 Channel cats------------------------------------------0.5 The above figures are admittedly arbitrary, but some line of separation was necessary, and they were adopted in this study because, in fishing experiments where no size limits were placed on the catch, they were found to be the smallest sizes that the public would utilize. All fishes of the above sizes or larger were grouped under "large fish" in the populations given in the Appendix. It will be noted that such species as the gar and shad, which are normally not harvested, are included. If they were produced by the population and were available for use, they were included in the AT value. In order to differentiate used and unused portions of the population available for harvest, it is suggested that: A$ represent that portion of the AT value composed of species. that are normally harvested, and AN represent the portion composed of unharvested species, and consequently, AT - AH ±A T -BALANCED and UNBALANCED FISH POPULATIONS 21 BALANCED and UB~ALACED FISHI POPUPLAIONS 2 From the standpoint of population studies, this would appear much more logical than separation of the population into artificial groups, such as game fish, pan fish, food fish, and rough fish. Large groups of unharvested adult fishes, regardless of whether they are bluegills or gizzard shad or another species, have a depressing effect upon the "C" groups in a population, which could be dissipated if harvesting were practiced. CALCULATION OF AT VALUES. In one experiment, a pond was stocked with 140 gizzard shad, 1,500 bluegill fingerlings, and 100 bass advanced fry per acre. Two years later, the pond was drained and the following fishes recovered per acre: Pounds 356 large bluegills 19,546 small bluegills _-------_______-------..--- ___w_ 1.------2 92 large gizzard shad -_ -677.2------8,124 intermediate gizzard shad o small gizzard shad ------------- -------------------- 0.0 8 large largemouth bass----------------------------16.4 ------------------- 0.0 0 small largemouth bass ----------- -----4248.4-__-------___ 56.4 -_ -_6 Total---------------------------------------1,079.6 The total weight of large fish is 56.4 pounds large bluegills + 81.2 pounds gizzerd shad 16.4 pounds bass = 154.0 pounds. The AT value is then: + AT= 154.0 x100=14.2 1079.6 If it is wished to subdivide this value: 54.4 lbs. (large bluegills) + 16.4 lbs. (large bass) A 0 . 1079.6 81.2 pounds (large and AT= shad) ± 7.5 xlOO0= 7.5 1079.6 andAT=AT+A = 6.7 = 14.2 In order to interpret these values, it is necessary to know the distribution of AT values in balanced and unbalanced populations. AT VALUES IN~ BALANCED AND UNBALANCED POPULATIONS. Frequency distributions of AT values in the various populations studied are shown graphically in Figure 5. The range of values for balanced populations 22 22 ALABAMA ALBAMA AGRICUTRLEPRMN AGRICULTURAL EXPERIMENT STATION TTO Number 12 8 Balanced Populations 33 6 .. ) Unbalanced Populations 10 I FIGURE 5. Frequency distribution of AT values in balanced and unbalanced populations. was 33 to 90, while in unbalanced populations it was 0 to 40, except for two cases. These two cases were populations 2 years old containing two species-largemouth bass and green sunfish (Tables 12-U and 21U). The latter species proved unable to maintain itself under bass predation and had practically disappeared from the populations. The AT values of 58.4 and 72.7 for these populations were temporary values that could not be maintained over a longer period of time. This condition could not occur in older established populations and would seldom be encountered in fisheries investigations. The AT values of balanced and unbalanced populations overlapped in the range from 33 to 40. The unbalanced populations in this range bordered upon balance and the balanced populations bordered upon unbalance. Outside of this narrow overlapping range, the AT values alone appeared to differentiate fairly definitely balanced and unbalanced populations. Within the range of balanced populations, the most desirable portion of the range appeared to be between 60 and 85. Populations with AT values above 85 had too few intermediates for replacements and too few small fishes to furnish adequate food for the "C" species; in other words, this was the range containing populations having overcrowded "C" fishes. Even in the range from 80 to 85, growth of the "C" groups was unsatisfactory due to slight overcrowding. BALANCED and UNBALANCED FISH POPULATIONS 23 In the range from 33 to 40, the "C" groups in balanced populations grew at a rapid rate, but the populations were less efficient in that relatively large percentages of their weights were of small and intermediate fishes. STABILITY OF AT VALUES. During the process of harvesting large fish in a population, the AT value must necessarily decrease and in a balanced population it must subsequently increase in order to provide a harvestable crop for the following year. The rapidity and extent of this replacement is a measure of the satisfactory nature of the balance in the population. While the AT values fluctuate, these results indicate that they must fluctuate within the limits of 83 to 90 if the pond is to remain in balance. Normally, the processes of depletion by harvest and replacement by growth are going on concurrently, and fluctuation in the AT values does not reach these extremes. In one experiment where the crop was removed in approximately equal weekly amounts for a period of 1 year, the results were as follows: December 1939 initial population Removed by fishing 1940 December 1940 remaining population Total weight (pounds) AT value 616.4 81.7 8839.5 869.6 88.9 With a slow rate of harvest, the AT value remained relatively constant and the depletion was in the total weight of the population. In other experiments, the application of heavy fishing pressure removed 70 per cent of the harvestable crop within 2 weeks, with a correspondingly rapid decline in AT value. However, hook-and-line fishing alone has not reduced the AT value in any experiment below the 40 per cent required for good balance in a population. On the other hand, where the crops were removed in part by seining and the AT values were reduced to 28.6 and to 20.7 in two ponds (Tables 10-U and 11-U), both populations became unbalanced and no fish of harvestable size could be caught the following year. This value is the most useful indicator of balUSES OF AT VALUEi. ance and is a measure of the efficiency of a population in production of harvestable fish. The conditions in populations indicated by various AT values are summarized in Figure 6. As has been indicated, these should be of value in the study of the effect of rates of harvest upon a population, The range of this value in balanced populations also limits the methods that may be used in stocking new waters to obtain balanced populations. It is obvious that, if balanced populations are to be 24 ALABAMA AGRICULTURAL EXPERIMENT STATION InficienF1 I r1 Range of balanced populations Desirable I ranrange I 33 Overcrowded CSpecies I I - =0 10 20 30 40 50 60 70 80 90 100 All populations No unbalanced populations in this unbalanced range except a few not over 2 years Normal range of unbalance old with F species disappearing FIGURE 6. Conditions in fish populations indicated by various AT values. expected within a minimum period, enough fish must be stocked so that 1 year later their weight will make up more than 33 per cent of the total weight of the population. For instance, if a body of impounded water is capable of producing 400 pounds of fish and is stocked with only 100 bass fingerlings plus 100 bluegill fingerlings, the following population may be expected 1 year later: 70% survival of 100 stocked bass------70 bass 75% survival of 100 stocked bluegills--------75 The population composition at the age of 1 year would bluegills. be: Pounds 70 large bass---------------------------------70 75 large bluegills------------------------------------25 Total small and intermediate fishes---------------------------305 Total---------------------------------------------------------400 In this population, the AT value would be: 70 + 25 400 x 100 =23.8 The result is, therefore, an unbalanced population at the end of 1 year. It can come into balance only if the bass are able to reproduce during the second summer, and no large fishes are removed until their combined weight exceeds 132 pounds. If bass duce because of the overcrowded small bluegills (23), the population would probably never come into a balance because natural mortality of the large bass during the second summer might prevent attainment of an AT value in the balanced range. -were unable to repro- BALANCED and UNBALANCED FISH POPULATIONS BALANCED and UNBALANCED FISH POPULATIONS 25 25 The minimum rate of stocking with bluegills bass to achieve the minimum desirable AT = 40, could be calculated as follows: 400 x 40% = 160 pounds of large fish in population. Stocking 100 bass yields 70 pounds of large bass (70% survival), as calculated, and, 160 - 70 = 90 pounds of large bluegills in population. Since bluegills may be expected to grow to 4 ounces in the first year, 90 x 4 = 360 large bluegills in population 1 year after stocking. Since the average mortality among the stocked bluegills is approximately the number to be used in stocking would be: 100 75 Similarly, if a more desirable AT = 70 is wanted, the calculated rate of stocking that may be expected on the average to achieve this condition would be 100 bass plus 1,120 bluegills. It will be noted that in these calculations, the number of bass was kept constant. This was done because experiments have shown that approximately 100 bass per acre is the maximum number that will reach approximately a 1-pound average size in 1 year. It should also be noted that the AT value relates methods of stocking to total productivity; consequently, the number of fish necessary in stocking to achieve balance is dependent upon the fertility of the water to be stocked. E VALUES DEFINITION. The E value of a species or group is the percentage of weight of the entire population composed of that species or group. REASONS FOR CALCULATION. )0, Sx 3860 = 480 bluegill fingerlings The ability of various species of fish to maintain their abundance in populations under the pressures of predation, cropping, and competition with othek species determines largely their relative importance as food or game fishes. This ability will be called the survival efficiency or E value of a species for convenience of discussion. It is affected by such factors as reproductive habits, reproductive capacity, food habits, adult size, rapidity of growth, and adaptation to various environments. Since each species within a population is in a sense a competitor with the others, the percentages of total weight of the population due to each species should be a measure of its relative survival efficiency under those environmental conditions. Many authors including Tarzwell (24), Ben- 26 ALABAMA AGRICULTURAL EXPERIMENT STATION nett (3), and Ball (1) have reported results of population studies in this form. It must be remembered that survival efficiency or E value of a species is of importance only if a large percentage of the individuals that survive reach a desirable size year after year and thus produce a harvestable annual crop. This condition can occur only in balanced populations. Consequently, the E values of species is of interest principally in various balanced combinations of species. E VALUES IN BALANCED POPULATIONS. For simple populations composed of only 1 "F" species and 1 "C" species (e.g. bluegills and largemouth bass), the range of E values for the two species can be calculated from the range of F/C ratios in balanced populations (Figure 2), as follows: F/C = 1.4= - 1.4 1 x 100 = 41.6 E Largemouth bass=- 1 2.4 Similarly in the upper range of F/C = 10 = E Largemouth bass = 9.1 10 1 Therefore, the range in E values for this species in balanced populations is from 9.1 to 41.6 per cent of the population. Similarly it can be calculated that the desirable range is between 14 and 25 per cent. The averages in 26 balanced populations composed of only bluegills plus largemouth bass were: E E Largemouth = 22.8 = 77.2 BZuegizls Total = 100.0 The E values for various species in balanced populations are given in Appendix Tables 1, 2, and 8. UsEs OF E VALUE. If additional "F" species are added to this simple combination, the E Bluegil value should decrease and the addition of other C species should reduce the E Largemouth value. Due to the range for EF and Eo in balanced populations, the effect of additional species can be determined only in rigidly controlled experiments or from the averages of many populations. The E values, therefore, are significant BALANCED and UNBALANCED FISH POPULATIONS 27 only when the combination of species in which they occur and the condition of the population, whether balanced or unbalanced, are given. For instance, in a balanced population containing bluegills, largemouth bass, and white crappie, E Largemout = 6.1 gives considerable information. It is evident that if this is a balanced population, the E value for this species was low because of competition with another "C" species, the white crappie. In this population, E white crappie - 5.8 substantiated the statement that these two species were competitors, (Table 37-B). Consistently low E values for a species in various combinations of species would indicate that the species was of relatively little importance from the standpoint of sport fishing or commercial fishing. RELATIONSHIPS WITHIN SPECIES The relationships discussed thus far have been between the various groups and species within the population. This has yielded information under conditions of balance and unbalance on the relationships between "F" and "C" groups of species, between the weights of the large fishes and the entire populations, between total weights of "C" groups and the small fishes upon which they feed, and also on the relative efficiencies of species in various combinations. A study of relationships between various groups within each species is also necessary to more fully understand the dynamics involved in balanced populations. The conventional methods used in the study of a species include the division of the individuals into various age or length-frequency groups and the determination of their length-weight relationships and coefficients of condition (9, 8, 26). While such studies yield information of value, they in reality are an attempt to study growth and abundance of a species as though it were an isolated group and not a part of a dynamic population. Consequently, these methods were considered of little value for the present studies and the division into groups within a species was based upon their function within the population. A, I, AND S VALMUES The division in this work of a species into three groups - large, intermediate, and small - has already been discussed and each group has been defined under previous sections. Briefly, the "large" fish are those of suitable size for harvest, and minimum sizes for this group are given under the discussion of the AT value. The "intermediates" are those between the sizes in the "large" and "small" groups. 28 ALABAMA AGRICULTURAL EXPERIMENT STATION The "small" fishes are those that are sufficiently small to be eaten readily by the average-size "C" fishes in the "large" group. This, then divides a species into functional groups - those ready for harvest, the primary replacements, and those available to the "C" group as food. The sizes to be placed in the "small" group were determined for each species in a population by arbitrary selection of the largest forage fish that the average-size adult "C" fishes in that population could easily gulp. This size was then used as the dividing line between "small" and "intermediate" fish. The length frequencies were determined for each group in some of the populations. However, after consideration it was decided that length measurements among these groups were worthless. Since the "C" species can eat only sizes that they are able to gulp and swallow, the maximum depth or girth of "F" species would appear to be the only dimension of importance to the fishes in a population. Unfortunately, this conclusion was reached too late for such measurements and correlation with the requirements of "C" species of various sizes to be made for the populations studied. The numbers of fish and weights in each group of the various species are reported in the appendix tables. In order to facilitate comparisons, the relative weights of each group are expressed as the A, I, and S values of a species. DEFINITION. As is the percentage of total weight of a species composed of fish in the "large" group. Is is the percentage of total weight of a species composed of fish in the "intermediate" group. Ss is the percentage of total weight of a species composed of fish in the "small" group. METHOD OF CALCtULATION 892 large bluegills - - 151 intermediate bluegills 81 small bluegills 53 large largemouth bass The following population is given: - - --- - -- ---- --------------------------------------.........-------------------------.........--------------------------------------- Pounds 68.4 10.3 1.6 --------------------- 86.1 20.6 225 small largemouth bass ------- Total ----- ---- 137.0 In order to determine the A, I, and S values for bluegills, the total weight of bluegills is first determined: BALANCED and UNBALANCED FISH POPULATIONS 29 ALANED and UNBA81LANCED ISH PPULAIONS 2 68.4 + 10.3 + 1.6 = 80.3 pounds. Then, 68.4 A Bluegill = X 100 = 85.2 80.3 10.8 I Bluegill = X 100 = 80.3 1.6 ll Bluegi 12.8 2.0 S = 80.3 < 100 = A -+ I + S = 100.0 DISTRIBUTION OF A, I, AND S VALUES FOR BLUEGILL IN A BLUEGILLBASS COMBINATION. In order to determine the significance of these values in a population, their ranges, averages, frequency distributions, and interactions will be considered in a simple population containing one "C" (largemouth bass) and one "F" (bluegill) species. To facilitate the discussion, these values'for bluegills will be designated AB, 'B, and SB. Frequency distributions of AB values for balanced and unbalanced populations are shown graphically in Figure 7. The range was from Number Balanced Populations HIP 182 Ae2 10 20 30 40 50 60 70 80 90 99.6 .- Unbalanced Populations balanced and unbalanced populations FIGURE 7. Distribution of AB values composed only of bluegills and largemouth bass. in 30 ALABAMA AGRICULTURAL EXPERIMENT STATION 18.2 to 99.6 m balanced populations, with an average of AB = 58.9. The unbalanced range was from 1.2 to 25.7, with an average of AB 10.6. Within the balanced range, AB values below 35 were found only in populations verging on unbalance and values above 85 occurred only in populations overcrowded with the "C" species. The most desirable part of the range was from 60 to 80 and the minimum AB value in a satisfactory population was 85.5. It is probable, therefore, that AB = 35 represents approximately the maximum allowable depletion of the stock of large fish of the "F" group if satisfactory balance and consequently satisfactory production is to be maintained in a population. Frequency distributions of IB values for balanced and unbalanced populations are shown in Figure 8. It will be noted that the range and frequency distributions were approximately the same in both groups. In the balanced group, the range was 0 to 20.2 with an average of IB = 6.6. In the unbalanced group, the range was 0 to 13.2, with an average of IB = 5.4. It is apparent that the intermediate group of the "F" species normally made up less than 7 per cent of the total weight. Frequency distributions of the SB values in balanced and unbalanced populations are shown in Figure 9. The range in balanced populations was 0.4 to 80.9, with an average of SB = 34.5. The range in the unbalanced group was 64.4 to 95.5, with an average of S = 84.2. While the two ranges overlap, it is apparent that SB values of 81 or higher indicate unbalance. Within the balanced range, populations with SB values in excess of 60 were relatively unsatisfactory. Those with values less than 10 were overcrowded with the C species and the most desirable range was between 15 and 40. A, I, AND S VALUEs FOR COMBINED F SPECIES. These values represent the respective percentages of total weights of the "F" species composed of large, intermediate, and small fishes. They will be designated by AF, IF, and SF for convenience in discussion. An examination of all populations showed that where the population contained more that one "F" species, the AF, IF, and SF values correspond almost exactly in range, distribution, and significance with the AB, IB, and SB values in the simple bluegill-bass population previously discussed above and shown in Figures 7, 8, and 9. The summarized information on conditions in populations indicated by AF values given in Figure 10 is based on the results from all populations. No summarization is given for the Ir values, since the values in balanced (0.0 to 41.4) and unbalanced groups (0.0 to 100.0) overlap to such an extent as to render them relatively useless. Information on the conditions indicated by SF values is given in Figure 11. BALANCED and UNBALANCED FISH POPULATIONS 31 BALNCED and UNlcBALACED FISH PPULATINS Nlumber 3 12 10 8 4 6 2 62 =.i I. H Balanced Populations HNnbapusd oplaton i FIGURE 8. Frequency distribution of 'B values in balanced and unbalanced populations composed only of bluegills and largemouth bass. I Number 4- 3 2 Balanced Populations 10 20 30 40 50 60 70 80 64.4 9095.5 100 Unbalanced Populations FIGURE 9. Frequency distribution of SB values in balanced and unbalanced populations composed only of bluegills and largemouth bass. 32 ALABAMA AGRICULTURAL EXPERIMENT STATION Minimum Satisfactory Value Balanced Range Range C Species 80 99.6 Range A,= !2 8.2 35 25.7 ' 45 60 Unbalanced Range FIGURE 10. Conditions in populations indicated by various AF values. Range cOsecre 0.4 in balanced populations Populations rL 15 Range 20 30 40 50 60 SF= 10 70 80 90 95.5 IF Overcrowded Groups Range in unbalanced populations FIGURE 11. Conditions in populations indicated by various SF values. Here, consideration of all populations increased the range of SF values in unbalanced populations to from 20 to 95.5, which included populations unbalanced due to overcrowded IF groups. It is probable that the same range would have been found for simple bluegill-bass combinations if sufficient unbalanced populations had been examined. It must be pointed out that, with the presence of additional "F" species, the As, IB, and Ss values in such populations will no longer have the same distribution as the AF, IF, and SF values. For example in the complex population given in Table 52-B, the IB value is 75.3, far higher than the distribution in balanced populations containing only bluegills and bass given in Figure 8. However, if the IF value is calculated, it is found to be 18.9 and falls within the balanced range. As another example, in the population given in Table 24-U, the AB BALANCED and UNBALANCED FISH POPULATIONS 33 value is 61.8. In the distribution given in Figure 7 for the AB values in simple bluegill-bass combinations, this would indicate a balanced population. However, in the population in question, a second "F" species, the gizzard shad, occurs. Consequently, the AF value must be used. This value is 15.5, indicating the unbalanced population that it actually is. The foregoing results illustrate the erroneous conclusions that are likely to result if a species within a population is considered as a separate and distinct unit. It was apparent from these studies that a simple bluegill-bass combination could be used to represent other and much more complex "F"-"C" combinations. STABILITY OF AF, IF, AND SF VALUES. These values are obviously not static values but subject to change due to harvest, predation, and growth. Since, however, they are percentages of the "F" population, the rate of change is not as rapid as might be expected. For instance, in a population subjected to very heavy fishing, it was found possible to reduce the large "F" fishes by 38.2 per cent in 5 days of hook-andline fishing. Since in this period the change in weights of intermediate and small fishes would be practically nil, it was possible to calculate the approximate changes in AF, IF, and SF values resulting from this heavy rate of fishing (Table 2). It will be noted that the reduction of 38.2 per cent in the weight of large "F" fishes reduced the AF value by only 7.7 due to the simultaneous reduction in total weight of the "F" population. It should also be noted that the reduction of 7.7 in the AF value increased the IF value by 0.6 and the SF value by 7.1. The reduction in total weight of the "F" population had the effect of increasing the food available for each pound of the fish remaining. Also, the shifts in AF, IF, and Sr TABLE 2. CHANGES IN AF, Ir, AND Sr VALUES DURING 5 DAYS OF FISHING Groups of "F" fishes 6/18 Amount caught 6/19 Lb. Lb. 0.0 Dates 6/21 Lb. 26.4 6/23 Lb. 49.3 Large "F" fishes remaining .........-------- 294.0 Intermediate "F" fishes remaining . 4.0 Small "F" fishes remaining _ .. 58.0 Total amount "F" species .. 851.0 AP values_ __---------83.8 Ir values -......-----------------------Sr values--...------1.1 15.1 ----------------___ _-- 836.4 257.6 4.0 53.0 814.6 81.9 1.8 16.8 231.2 4.0 58.0 288.2 80.2 1.4 18.4 181.9 4.0 58.0 238.9 76.1 1.7 22.2 34 ALABAMA AGRICULTURAL EXPERIMENT STATION values correspond to shifts in the relative percentages of the food supply available to each group. The increased food available to the IF group normally results in the subsequent movement of individuals from the intermediate into the group of large fishes. As a result of the interaction of increased growth and predation in the S group, replacements move up into the I group. Insufficient records are available to render at this time a more detailed study of these changes. As a result of harvest of part of the "F" species and accompanying increase in food available for the AF group, more rapid growth and increased reproduction will result. Since the small "F" fishes will subsequently increase in numbers and since they have available a larger percentage of the food supply, the weight of this group will tend to increase. However, these small fishes function as the food supply for the "C" group, and the increase should be largely passed on to the latter, since it has been shown that the Y/C ratio is a constant within limits. INTERRELATIONSHIPS BETWEEN AF, SF, AND C VALUES. It is apparent from the foregoing discussion that interrelationships exist between the AF and SF values and the total weight of "C" species (or C value) in a population. In order to more fully understand their nature and the extent of their importance, a series of 12 balanced populations containing principally bluegills as the "F" species and only largemouth bass as the "C" species were selected for further analysis. The ponds containing these populations were fertilized at a uniform rate to give relatively uniform productivity. They were fished at various rates for 1 to 6 years, thus insuring dynamic populations. They were then TABLE 8. 1 THEim AF, SF, AND C VALUES OF BALANCED DYNAMIC POPULATIONS IN CAPACITY 3 WATERS WITH APPROXIMATELY EQUAL PRODUCTION Population "C" value2 in pounds per acre Correction factor A S 2.0 40.5 62.2 1B 9 B 10 B 56.7 60.2 102.83 0.3 25.3 37.3 29.6 85.2 44.1 24.9 11 B 37.7 56.0 8.7 8.6 67.8 38.0 26.1 54.6 12 B 13 B 24 B 60.1 48.1 27.6 38.9 41.4 5.9 9.9 7.8 19.0 74.6 53.4 20.4 26 B 27 29 32 55 B B B B 88.2 57.6 34.2 57.8 37.4 40.4 50.7 65.4 72.2 87.2 59.6 44.5 25.4 27.8 12.8 proximate additional "C" value still present as small fishes. 1Population numbers refer to table numbers in Appendix. 2 Total pounds of largemouth bass per acre. 3Total pounds of small "F" fishes per acre divided by five. This gives the ap- BALANCED and UNBALANCED FISH POPULATIONS 35 drained and the numbers and weights of the various groups determined. The summarized results are given in Table 3. The weights of "C" fishes in these populations were obviously not the result of the small fishes present in the populations at the time both were censused but were the result of the small fishes previously present. However, both groups present concurrently were the result of previous conditions in the population. It would, therefore, appear possible to establish in a general way some relationship between the SF value and the pounds of "C" species in dynamic populations; that is, those that are in the process of replacing harvested "F" and "C" groups. In Figure 12, the SF values were plotted against the pounds of "C" fish per acre taken from Table 3. The coefficient of correlation (18) between these values, with significance indicated at the 1.2 per cent level, was +0.701, indicating that an increase in the SF value in a population is accompanied by an increase in the total pounds "C" species per acre. In static populations, there would probably be a reverse relationship because high concentrations of "C" species would eventually result in reduction in the SF value and increase in the AF value. It would be much more important from a management standpoint to establish some relationship between the AF and the "C" values because of the great interest of the fishing public in "C" species and also because it is possible to change the AF value by harvest of adult fishes. It must be remembered that the degree of success of a majority of natural waters and most of the large impoundments is measured largely by their ability to produce "C" species. Consequently, the dynamic populations in Table 3 were examined for possible relationship between the AF values and the pounds per acre of the "C" species. A graph with AF values plotted against the actual weight per acre of the "C" group is given in Figure 13. The coefficient of correlation between these two values, with significance indicated at the 2.5 per cent level, was -0.646. In general, this indicated that as the AF value decreased, the pounds of "C" species per acre increased. In these populations at the time the censuses were made, there were certain weights of "C" species representing small fishes previously consumed, plus a certain weight of small fishes yet to be utilized. The latter are represented in column three of Table 8 as a correction factor or the "C" equivalent of these small fishes. This was computed, assuming that 5 pounds of small fishes was equal to 1 pound of "C" species. If now the AF values are plotted against the actual weights per acre plus the correction factors per acre for the "C" species, the 36 36 ALABAMA AGRICULTURAL EXPERIMENT STATION ALABAMA AGRICUTRLEPRMN TTO CValue in pounds per acre SF Value FIGURE 12. Relationship of Sr values to pounds per acre of "C" species in dynamic balanced populations from waters of approximately equal productivity. Coefficient of correlation r =- +0.701, t =- 83.108, d.f. = 10. C Value in pounds per acre 100 80 70 60 o o Fz 30 20 10 20 30 40 AF 50 Values 60 70 80, 90 FIGURE 13. Relationship of A values to pounds per acre of "C" species in dynamic balanced populations from waters of approximately equal productivity. Coefficient of correlation r = -0.646, t = 2.6764, d.f. = 10. BALANCED and UNBALANCED FISH POPULATIONS 37 coefficient of correlation is found to be -0.740, with significance indicated at less than the 1 per cent level. Since the AF + IvF + S values = 100, and since the IF value is normally low, a relatively high degree of negative correlation may be expected between the AF and SF values. In the above populations, the coefficient of correlation between the two was -0.782, and t 3.968 with 10 d.f., indicating significance at less than the 1 per cent level. The fiducial limits of the coefficient in the population from which the samples were drawn were -0.212 to -0.959. This indicates that decreasing AF values are accompanied by increasing SF values in dynamic balanced populations. CHANGES DUE to RATES of HARVEST in BALANCED POPULATIONS The relationships in fish populations previously discussed throw considerable light upon the effect of rates of harvest upon various parts of the population. These have been discussed in part under the sections dealing with the various ratios and values. In order to systematize and integrate this miscellaneous information, the effects of rates of harvest of the "F" and "C" groups will be discussed separately. In this discussion it will be assumed that the harvest of large fishes means their removal from their aquatic environment by fishing or otherwise. In the absence of harvest, natural mortality alone is assumed to regulate the rate at which the stocks of large fishes are dissipated. Since harvest of adult fishes may be expected to reduce losses due to natural mortality, low rates of harvest tend in part to replace as well as supplement such losses. EFFECTS DUE TO HARVEST OF "F" SPECIES. The negative correlation established between AF and SF values indicated that harvest of the adult "F" species was accompanied by an increase in the relative abundance of and in the food supply for the "S" group. The positive correlation between the SF and C values demonstrated that the weight of "C" species per acre increased with increase in the SF value. The negative correlation between AF and C values substantiated the foregoing conclusions that harvest of the adults in the "F" group increased the weight of the "C" group in the population. It is evident from these relationships that the abundance of small "F" fishes in a population where the food supply remains a constant is regulated by two factors - the AF value and the C value. Consequently, if the AF group is not harvested, the pressure of predation reduces the SF value and part of this group passes into the intermedi- 38 ALABAMA AGRICULTURAL EXPERIMENT STATION ates and into the A group, thus increasing the AF value. This results in reduction of the weight of "C" fishes in the population. These results have been corroborated in pond management experiments. Failure to harvest the adult bluegills in bluegill-largemouth bass combinations repeatedly has been found to reduce greatly the production of young bluegills and subsequently reduced the production of bass. Heavy fishing in such ponds was normally followed with heavy reproduction of young bluegills within 1 month and subsequent improvement in the condition of the bass population. Therefore, if maximum increase in the piscivorous sport fishes, such as bass, pickerel, pike, crappie, and others, is desired, it is necessary to harvest the large forage fishes in the population. Failure to harvest this group adequately results in a static population with high AF and low SF values and subsequent decline in the "C" species. This problem is especially acute in populations with relatively high AT values due to the presence of gizzard shad or other undesirable fishes that are entirely unharvested. In such cases the production of small fishes is dependent upon the rates of nautral mortality of these species. In populations in Tables 23-U, 24-U, and 25-U, the presence of unharvested large and intermediate gizzard shad prevented the production of young bluegills and young gizzard shad during the entire summer before the ponds were drained and consequently prevented the survival of any young bass. In the balanced population given in Table 52-B, unharvested gizzard shad, carp, buffalo, and suckers reduced reproduction in the "F" group so that the Y/C ratio was 0.3. This resulted in the bass being divided into rapid- and slow-growing groups. The large bass, with average weights above 2.43 pounds, were growing well because they could eat the fishes in the IF group. The small bass of the current year were thin and starved because of the low reproduction of the "F" group. In the population in Table 54-B, the same unharvested species reduced the spawning of the "F" group so severely that the Y/C ratio was 0.07 and all "C" species were unable to grow at a satisfactory rate. EFFECTS DUE TO HARVEST OF C SPECIES. Slow annual rates of har- vest of the adult "C" group or losses such as those normally occurring due only to natural mortality in this group have been shown to result in a reduction in the Y/C ratio. Since under such conditions, the "C" value tends to change very slowly, the reduction is largely in the value of Y. Reduction in the Y value has the result of reducing the SF and increasing the AF values. This has been shown to result in a reduction in the weight of "C" fishes in the population. It is thus evident that failure to adequately harvest "C" species results in less pounds of "C" species for future harvest. Long-continued slow rates of harvest or failure to harvest the "C" BALANCED and UNBALANCED FISH POPULATIONS 39 species also affects the "F" species in the following manner: The resulting reduction of the Y/C ratio tends to move the ratio into the inefficient or overcrowded "C" range (Figure 4). Under these conditions, too few small "F" fishes survive predation to move in adequate numbers into the I and A groups. As a result of insufficient numbers, the food supply is inadequately utilized and the total weight of the "F" species declines. Evidence is accumulating that the F/C ratios in such populations shift also toward the inefficient range of 1.4 to 2.0 (Figure 2). Failure to harvest adequately "C" species is thus shown to temporarily increase the AF value and improve fishing for these species, but when continued over a long period (more than 1 year), it eventually reduces the pounds of "F" species available for harvest. Severe reductions in the Y/C ratio as a result of long-continued low rates of harvest of the "C" species has one other effect that has been observed in seining ponds in controlled fishing experiments. It has greatly reduced the rate of growth and greatly reduced or entirely prevented survival of young-of-the-year "C" species. It also has caused loss in weight or condition of the large individuals in the "C" group and this eventually has had the curious effect of making these fishes very hard to catch by either pole-fishing or casting. More rapid rates of harvest of the adults in the "C" group tends to maintain or increase the Y/C ratio and consequently maintain or increase the weight of the "C" species available for harvest. This also results in more rapid growth and higher survival of the young "C" fishes and in adequate survival in the "F" group for maintenance of high production. It has also been shown possible to deplete the "C" group too rapidly. Where seining was used to harvest largemouth bass in two populations (Table 10-U and 11-U), so many were removed that the AT required for balance and the values fell below the minimum of 3388 F/C ratios moved up into the unbalanced range. Heavy mortality in the "C" group from low oxygen or other causes has had similar effects. 40 ALABAMA AGRICULTURAL EXPERIMENT STATION SUMMARY Various relationships between groups and species and the dynamics of various interrelationships were determined for 55 balanced and 34 unbalanced fish populations. Balanced populations were defined as those capable of producing satisfactory annual crops of harvestable fish. They were characterized by having (1) a definite range in ratios of the weights of forage and piscivorous groups, (2) a narrow range in the ratios of weights of small forage fishes to the weights of piscivorous groups, and (3) more than 33 per cent of the total population weight in the form of fishes of harvestable size. A fish population may be divided into two classes - the "C" class, composed of species that feed principally upon other fishes and that cannot attain normal adult size without such food; and the "F" class, composed of all other species in the population that feed principally upon plants, plankton, water insects, and other small aquatic invertebrates. The "C" value is the weight in pounds of the "C" class and the "F" value is the weight in pounds of the "F" class. The F/C ratio equals the "F" value divided by the "C" value. The range of F/C ratios in balanced populations was from 1.4 to 10.0. Populations with F/C = 1.4 to 2.0 were overcrowded with "C" species. The most desirable populations were those with F/C ratios between 8.0 and 6.0. Unbalanced populations with disappearing "F" species had F/C ratios from 0.06 to 2.7. All populations with F/C ratios above 10.0 were unbalanced. Balanced populations with F/C ratios below 3.0 were inefficient due to overcrowding of the "C" species. This was found to reduce the total weight of the population. The F/C ratio was a relatively stable value, remaining almost constant despite variations in the rates of fishing for "F" and "C" species. This ratio is useful in comparing and in determining the condition of populations. It may also be used to determine the rates of stocking new ponds with bluegills and bass and it relates rates of stocking to the productivity of pond waters. The Y value in a population is the total weight in pounds of all fishes in the "F" class which are small enough to be readily gulped by the average-size adult in the "C" class. The Y/C ratio is an expression of the food available to the "C" class. In balanced populations, the range in Y/C ratios was from 0.02 to 4.8. All populations with Y/C -= 0.02 to 0.5 were severely overcrowded with "C" species. The most desirable populations were in the range Y/C = 1.0 to 8.0. All populations with Y/C ratios in excess of 4.8 were unbalanced and in- BALANCED and UNBALANCED FISH POPULATIONS 41 capable of producing yearly crops of harvestable fish. This ratio was found to be a dynamic ratio, changing with changes in predation pressure and rates of harvest, yet remaining a constant within limits in balanced populations. The AT value is the percentage of the total weight of a population composed - of fish of harvestable size. In balanced populations, the range of this value was from 33 to 90. The most desirable populations had values between AT = 60 to 85. Values in excess of 85 indicated populations overcrowded with "C" species. Unbalanced populations occurred in the range AT = 0.0 to 40. The AT value fluctuated with rapid rates of harvest, but remained relatively constant under slow rates. The limits of the value in balanced populations indicated that AT = 40 was the maximum allowable depletion of adult fish stocks for the maintenance of satisfactory annual production and that depletion below AT 833 caused an unbalanced condition. The AT value is useful in determination of balance and comparison of the efficiencies of populations. Its range in balanced populations limits the methods that can be used in stocking new waters to obtain balanced populations. These values can be used to determine numbers of fish necessary for stocking new waters and to determine the probable results of various stocking methods. The E value of a species is the percentage of weight of a population composed of that species. The ranges of E values for "F" and "C" groups were calculated from the F/C ratios and found to agree with those in the populations studied. They are useful in determining the extent of competition between species. The "F" class and also the "F" species were subdivided into groups of "large", i.e. fishes of harvestable size; "intermediates," i.e. those too large to be eaten by the average "C" species and too small for harvest; and "small", i.e. the fishes small enough to be eaten by the average-sized individual in the "large" group of "C" species in the population. The AF value is the percentage of the total weight of the "F" class composed of "large" fishes. The Iv and SF values are the percentages of the total weight of the "F" class composed respectively of the "intermediate" and "small" fishes. The range in AF values in balanced populations was 18.2 to 99.6. Within this range AF = 385 appeared to be the minimum value found in desirable populations and apparently expresses the maximum allowable depletion of the adult "F" species if satisfactory production is to be maintained. Values above 85 occurred only in populations with overcrowded "C" species. The most desirable populations were in the range AF = 60 to 80. The unbalanced populations had AF values from 1.2 to 25.7. 42 .42 ALABAMA AGRICULTURAL EXPERIMENT STATION ALABAMA AGRICUTRLEPRMN TTO IF values overlapped in balanced and unbalanced populations. The range in the former was 0 to 41.4 and in the latter from 0 to 100.0. The SF values in balanced populations ranged from 0.4 to 80.9. Satisfactory populations occurred in the range 15 to 40. Values in excess of 60 indicated inefficient populations. The AF, IF, and SF values were found to be dynamic values shifting with changes due to harvest, predation, natural mortality, and growth. The coefficient of correlation between the AF and SF values in dynamic --0.782; that between AF and pounds of "C" populations was r species per acre (C value) was r = -0.646; and that between the SF and C values was r = +0.701. These results indicated that harvest of adult "F" species increased the pounds of "C" species per acre and that failure to adequately harvest the former group resulted in a decrease in the pounds of "C" species in the population. Failure to harvest adequately the "C" species was shown to reduce subsequently the pounds of "C" species available for harvest. This was also found to increase temporarily but eventually to decrease the adult F species available for harvest. When seining was used to harvest the "C" class, it was found possible to deplete them so rapidly that the populations became unbalanced. The ratios and values used in this study and the interrelationships established in 55 balanced and 34 unbalanced populations establish standards for comparison of other populations if the compositions of adequate samples from these populations are determined. The dynamic interrelationships in these populations provide a better understanding of the mechanism of balance and the effects of harvest. Consequently, they provide a basis for improved management practices. BALANCED and UNBALANCED FISH POPULATIONS 43 LITERATURE (1) BALL, ROBERT C. Recovery of marked fish following a second poisoning of the population in Ford Lake, Michigan. Amer. Fisheries Soc. Trans. 75(1945): 36-42. 1948. Survey Bul. 22 (3): 357-376. 1943. (2) BENNETT, GEORGE W. Management of small artificial lakes. Ill. Nat. Hist. (3) BROWN, C. J. D., AND BALL, ROBERT C. A fish population study of Third Sister Lake. Amer. Fisheries Soc. Trans. 72(1942): 177-186. 1943. (4) EMBODY, DANIEL R. A method of estimating the fish in a given section of a stream. Amer. Fisheries Soc. Trans. 69(1989): 231-236. 1940. 1937. (5) ESCHMEYER, R. W. Some characteristics of a population of stunted perch. Mich. Acad. Sci., Arts, and Letters. Paper XXII( 196): 613-627. (6) . Fish population of a small Norris reservoir bay. Tenn. Acad. Sci. Jour. XVIII (1): 47-48. 1948. (7) HASKELL, DAVID C. An electrical method of collecting fish. Amer. Fisheries Soc. Trans. 69(1939): 210-215. 1940. (8) HILE, RALPH T. Age and growth of the cisco Leucichthys artedi (LeSueur) in the lakes of the Northeastern Highlands, Wisconsin. U. S. Bur. Fisheries Bul. 48: 211-317. 1936. (9) HUBBs, CARL L., AND COOPER, GERALD P. Age and growth of the long- eared and green sunfishes in Michigan. Mich. Acad. Sci., Arts and Letters. Paper XX(1934): 669-696. 5 pl. 1935. (10) KRUHOLZ, Louis A. A check on the fin-clipping methods for estimating fish populations. Mich. Acad. Sci., Arts and Letters. Paper XXIX( 1948): 281-291. 1944. (11) (12) . The use of rotenone in fisheries research. Jour. Wildlife Mangt. 12 (38): 805-317. 1948. MEEHEAN, O. LLOYD. O'DONNELL, D. JOHN. Fish populations in five Florida lakes. Amer. Fish- eries Soc. Trans. 71(1941): 184-194. 1942. (18) (14) (15) The fish population in three small lakes in northern Wisconsin. Amer. Fisheries Soc. Trans. 72(1942): 187-196. 1943. X., AND ESCHMEYER, R. W. The estimate of fish populations in lakes or ponds. Tenn. Acad. Sci. Jour. XVIII(3): 228-249. 1943. SHUMACHER, F. SMITrrH, LLOYD L., JR., JOHNSON, RAYMOND E., AND HINER, LAURENCE. Fish populations in some Minnesota trout streams. Amer. Fisheries Soc. Trans. 76(1946): 204-214. 1949. Nova Scotia lakes. Amer. Fisheries Soc. Trans. 67(1937): 178-183. 1938. (16) SMITH, M. W. A preliminary account of the fish populations in certain 44 ALABAMA AGRICULTURAL EXPERIMENT STATION (17) Copper sulphate and rotenone as fish poisons. Fisheries Soc. 69(1939): 141-157. 1940. pp. 1946. Amer. (18) SNEDECOR, GEORGE W. Statistical methods. Iowa State Col. Press. 485 (19) SOLMAN, V. E. F. History and use of fish poisons in the United States. Dominion Ottawa (Canada) Wildlife Service, Lands and Development Branch, Department of Mines and Resources. Mimeograph. 15 pp. 1949. (20) SWINGLE, H. S. Improvement of fishing in old ponds. Tenth North Amer. Wildlife Conf. Trans. 299-308. 1945. (21) . Experiments with combinations of largemouth bass, bluegills, and minnows in ponds. Amer. Fisheries Soc. Trans. 76(1946): 46-62. 1949. (22) , AND SMITH, E. V. Experiments on the stocking of fish ponds. Fifth North Amer. Wildlife Conf. Trans. 267-276. 1940. (23) of bluegill bream and largemouth bass .in Factors affecting the reproduction 87. ponds. Ala. Agr. Expt. Sta. Cir. 8 pp. 1948. (24) TARZWELL, CLARENCE M. Fish populations in the backwaters of Wheeler Reservoir and suggestions for their management. Amer. Fisheries Soc. Trans. 71(1941): 201-214. 1942. (25) THoursoN, DAVID H., AND BENNETr, GEORGE W., Lake management re- ports. 2. Fork Lake near Mount Zion, Illinois. Ill. Nat. Hist. Survey Biol. Notes. 9 : 1-14. 1989. (26) VAN OOSTEN, JOHN. The age, growth, and sex ratio of the Lake Superior longjaw, Leucichthys zenithicus (Jordan and Everman). Mich. Acad. Sci., Arts, and Letters. Paper XXII(1936): 691-711. 1937. BALANCED and UNBALANCED FISH POPULATIONS 45 APPENDIX Page E values of species in balanced populations, Tables 1 to 3- _. 46-48 Composition of balanced populations, Tables 1-B to 55-B .-. 49-63 Composition of unbalanced populations, Tables 1-U to 84-U ---- 64-73 46 46 ALABAMA AGRICULTURAL EXPERIMENT STATION ALABA AGRICULTURALEXPERIMENTPSTATION Total pounds fish per acre 187.0 463.5 387.5 393.6 411.0 850.5 879.4 826.8 878.5 401.6 827.0 319.3 806.3 230.1 279.2 350.0 224.2 207.0 386.0 303.4 216.2 299.8 259.1 ~1 Largemouth bass E Y ~T~L~ T~LT 1T ~I 1 41.4 28.8 20.6 22.2 21.7 25.1 40.8 39.3 16.1 25.5 17.1 18.8 12.8 12.8 37.3 15.4 24.1 29.0 9.1 13.8 31.0 16.0 18.6 UV Bluegills E .___ 58.6 71.7 79.4 77.8 78.3 74.9 59.2 60.7 83.9 74.5 82.8 81.1 87.2 87.2 62.7 84.6 75.9 71.0 90.9 86.2 69.0 84.0 81.4 BALANCED and UNBALANCED FISH POPULATIONS TABLE 2. E VALUES OF SPECIES IN BALANCED POPULATIONS 47 Total lb. fish per acre :L.B. : B 452.7 819.3 327.0 525.5 440.1 146.6 197.3 371.3 236.2 408.0 404.0 611.0 302.0 301.8 474.1 284.8 311.6 147.2 108.0 104.1 199.8 515.8 515.4 20.0 18.8 17.1 11.0 10.3 23.3 19.0 16.6 24.5 138.2 12.9 20.8 21.2 6.1 15.8 10.1 11.7 14.4 22.9 23.0 21.7 13.5 12.4 E values for S :W.C.: W : G.S.C.S. : Y.B.:F.C. :G.S. 80.0 81.1 82.8 71.5 17.5 70.0 17.4 76.1* 76.7* 82.0 71.0 81.9 64.9 62.8 76.8 88.1 77.8 82.3 82.4 52.2 75.3 72.5 65.8* 49.6 75.8 2.83 1.0 1.1 4.5 4.9 22.2 16.4 2.0 5.8 6.4 7.6 5.9 23.6 0.0 12.4 7.4 12.2 9.8 1.8 4.5 0.1 0.3 17.9 0.1 11.3 L.B. = largemouth bass; B = bluegill; S = shellcracker; W. C. = white crappie; W =-- warmouth; G.S. = golden shiners; C.S. = chub suckers; Y.B. = yellow bullheads; F.C. = flathead cats; and G.S. = gizzard shad. * Plus shellerackers. 48 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 3. E VALUES OF SPECIES IN BALANCED POPULATIONS Species Largemouth bass ... 12.6 Bluegills-----_------------- 80.1 Shellcrackers ------_ White crappie 1.6 Warmouth ---------- E values 4.6 31.0 1.2 41.2 54.0* 68.1 0.8 28.2 21.4 59.9 6 4.1 2.3 ---. Golden shiners Chub sucker Flathead cats ---- 0.1 0.3 8.6 3.1 12.5 11.9 4.2 0.1 12.7** 1.9 0.5 0.0 14.7 22.4 12.2 4.3 5.7 0.1 -- Yellow bullheads Gizzard shad Buffalo -------------Goldfish 0.9 4.3 1.4 3.9 0.2 0.4 1.2 44.0 5.5 0.1 21.1 Gambusia Spotted suckers Speckled bullheads Carp _8.4 8.9 5.3 0.2 0.1 2.4 4.6 37.6 4.1 1.8 5.4 2.4 Gar -1.1 4.2 -21.6 - -13.6 Green sunfish -------Eel --------Bowfin Miscellaneous Total lb. 818.9 886.7 .....---------per acre . * Bluegills plus shellcrackers. ** Black crappie. Spotted bass Channel cats 1.0 3.4 48.0 77.9 100.8 426.0 0.2 1.3 4.1 31.4 216.3 BALANCED and UNBALANCED FISH POPULATIONS 49 BALANED and UNBALANCED FSH POPULAINS RECOVERED PER ACRE ON DRAINING, OCTOBER 4 TABLE 1-B. 25, 1948 Number 892 151 Species Large bluegills --_-------Intermediate bluegills Pounds --------------------- 68.4 10.8 -. 81 58 225 Small bluegills--------Large largemouth bass - - - _-__-___-_ 8__----6.1 20.6 187.0 Small largemouth bass-----------------------------------------Total-------------------------------------------------=0.03, AT = F/C = 1.4, Y/C TABLE 2-B. 76.3, A = 85.2, IF= 12.8, Sir= 2.0 RECOVERED PER ACRE ON DRAINING, SEPTEMBER 29, 1949 Number 852 92 Species Large bluegills ----------------------------------Intermediate bluegills-----------------8-_---------r---269.0 Small bluegills ----------------- ----------__-----_--w--_Large largemouth bass _ Pounds ---- .60.5 .0 48,860 80 48 Small Total -------------------------------------= 2.1, largemouth bass ----- --= 124.0 _ ___-- ---- 7.0--_463.5 F/C = 2.5, Y/G A = 89.8, Air 18.2, II=0.9,51=80.9 TABLE 8-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 4, 1949 Number 219 Species Large bluegills ---------Intermediate bluegills -- _____ Small bluegills Large largemouth bass Small largemouth bass Total ----------------------=----68.8 Pounds 16.0 ______ 276 26,468 228.2 4.5-----4 60 196 -75.5 887.5 - F/C = 3.8, Y/C = 2.9, A1 = 85.8, A 20.6,II=5.2,51 = 74.2 TABLE 4-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 5, 1949 Number 752 Species Large bluegills- Pounds -- __________197.2 -~-------___ - 280 9,972 Intermediate bluegills Small bluegills---------- 22.0 87.2 68 556 Large largemouth bassSmall largemouth bass Total---_------_-_------_-__-----398.6 '----------11 76.0 --- F/C =3.5, Y/O =1.0, AT =69.4, Air = 64.4, 11=7.2, 51 =28.4 so ALABAMA AGRICULTURAL EXPERIMENT STATION 50 TABLE.5-B. :ALABAMA GRICUTRLEPIMNSAIO RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number 448 864 86,480 48 116 Species Pounds Large bluegills ------------------------------127.0 Intermediate bluegills --------- ----------------- 24.8 Small bluegills ------------------------------------ 170.2 -------- 70.5 Large largemouth bass ------------Small largemouth bass ---------------------------- 18.5 -------------------- 411.0 Total----------------------------- F/C = 3.6, Y/G = 1.9, AT = 48.1, AT = 89.4, IF= 7.7, S=52.9 TABLE 6-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number 1,176 Species Large bluegills------------------179.0 Small bluegills --------------- Pounds 440 6,760 64 196 80.0 53.5 Large largemouth bass-----------------------65.0 ---------- 2.0 Small largemouth- bass----------Intermediate bluegills-------Total -------------------------------------------= ---------------- 350.5 F/C = 3.0, Y/C = 0.6, AT 69.6, AT = 68.2,IT=11.4, ST=20.4 TABLE 7-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 4, 1949 Number 1,016 172 13,086 84 Species Pounds 125.5 --------------------Large bluegills ------Intermediate bluegills ----------Small bluegills -----------Large largemouth bass 8.0 91.2 128.5 116 24 Intermediate largemouth bass ---------------------------- - ----------------- --------- 31.0 379.4 40.5 Total-------------------------------------------------------1.5, Y/C = 0.6, AT = Small largemouth bass_-------------------------------------0. F/C= 65.6, AT = 55.9, IT =3.6, ST = TABLE 8-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number 660 96 Species Large bluegills Intermediate bluegills ___------------------- Pounds -------------------------------------------------_--------------------------- 76.0 6.5 18,144 72 64 20 Small bluegills Large largemouth bass 115.8 120.0 8.0 0.5 326.8 Intermediate largemouth bass ------------------Small largemouth bass ---------_ ---Total ----- F/C = 1.5,-Y/C = ---- ---0.9, AT =60.0, AT =38.3, IT =3.3, ST =58.4 ---- ------ ---------- BALANCED and UNBALANCED FISH. POPULATIONS 51 BALANCED and UNBALANCED TABLE FISH. POPULATIONS 4, 1949 5 9-B. RECOVERED PER ACRE ON DRAINING, OCTOBER Number ..748 Species Large bluegills 880 27,260 56 Intermediate Small bluegills Total -188.3 bluegills -- Pounds -__-------- 4 48.2-----___-_ 10.2 ___--_-------______ Large largemouth bass _---------- 126.8 50.0 800 Small largemouth bass AT = 50.4, _------------------_--------378.5 F/C = 5.2, Y/C = 2.1, A7 = 44.1,I,= 15.4, ST=40.5 TABLE 10-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 5, 1949 Number 588 540 29,048 72 Species Large bluegills ---------------------Intermediate bluegills Small bluegills Large largemouth bass------________ Pounds -3 ------------ 74.5 186.3 88.5_____186.3___ 98.5 3.8 184 Small largemouth bass Total-------------------------AT ------- _------ ------------- 401.6 F/C = 2.9, Y/C = 1.8, = 48.1, A7 = 24.9,IF= 12.9, 57=62.2 TABLE 11-B. RECOVERED FROM 3.5 ACRES ON DRAINING, OCTOBER, 1949 Number 1,184 Species Large bluegills ___- Pounds 588 88,186 56 4 Intermediate bluegills __86_________.__ Small bluegills Small green sunfish _________----_______----2.8 -_----------__-- 389.9 -151.7 Large speckled bullheads __..__---8.5 2 114 216 Chub suckers, large Large largemouth bass---------__ Small largemouth bass__--------Total-----------------------------------------------------------AT =67.5, 89.5 42.5 722.3 1.6 F/C = 4.5, Y/C = 1.2, Ai = 67.8,I17= 6.1, SF= 26.1 TABLE 12-B. RECOVERED PER ACRE ON DRAINING, OCTOBER, 1948 Number 594 Species Large bluegills Pounds 887 26,740 ---------------------------------- 102.8 Intermediate bluegills Small bluegills 1 49 97 F/C =4.8, Shellcracker, large --Large largemouth bass Small largemouth bass Total --------_----_ -__---- 19.9 4.7 147.9 --------------------Y/C =2.6, ---_____ ----------------_.-- 0.4 51.3 827.0 AT = 47.2, AP = 38.1, I,= 7.8, 5, = 54.6 52 TABLE 13-B. ALABAMA AGRICULTURAL EXPERIMENT STATION RECOVERED PER ACRE ON DRAINING, OCTOBER 25, 1948 Number 860 1,565 5,228 23 75 13 Species Pounds Large bluegills------------------------------49. Intermediate bluegills ------------------------ 71.5 Small bluegills-------------------138.1 Warmouth, small ---------------------------0.3 Large largemouth bass -----------------60.0 Small largemouth bass-------------------------- 0.1 Total------------------------------------- 8319.3 2.8, AT = F/C = 4.3, Y/C TABLE 14-B. 84.2, AF = 19.0, I =27.6, SF =53.4 RECOVERED FROM 1.5 ACRES ON DRAINING, NOVEMBER, 1940 Number 1,724 46,630 135 Species Pounds Large bluegills-----------------------188.2 Small bluegills-----------------------------212.7 Large largemouth bass ------ -------------------- 58.6 Total -_-----------------------------459.5 F/C = 6.8, Y/C = 3.6, AT = 53.7,A = 46.9, SF=53.1 TABLE 15-B. RECOVERED FROM 1.5 ACRES ON DRAINING, NOVEMBER, 1941 Number 801 Species Large bluegills----------------------89.3 Pounds 14,155 27 Small bluegills---------------------211.5 Large largemouth bass _--- 263 Small largemouth bass- ------------- ------------ 13.3 = - -------- Total---------------------------------------------8345.1 F/C = 6.8, Y/C = 4.8, AT = 34.9, Ai TABLE 16-B. 29.7, S =70.3 RECOVERED PER ACRE ON DRAINING, AUGUST 18, 1943 Number 688 62,652 44 156 Species Large Small Large Large Pounds Total---FIG = bluegills -------------------------------------------- 128.0 bluegills ------------------------------------------47.0 largemouth bass, 3 yr. ------------------------------39.2 largemouth bass, 2 yr. ---------------------------65.0 ----------------------------------------AT 279.2 1.7, Y/G =0.5, = 83.2, A = 73.1, SF = 26.9 Pounds TABLE 17-B. RECOVERED PER ACRE ON DRAINING, AUGUST 18, 1943 Number 612 Species Large bluegills------------------------------------------ ---- 41,200 88 Intermediate + small bluegills 86 Large largemouth bass-------------------Small largemouth bass ----Total -------------- --------AT = ---------------_ 193.0 103.0 _47.0 -------------- 7.0 ----------------------- 350.0 F/C =5.5, Y/C =1.9, 68.6, A = 65.2, IF + Sr=34.8 BALANCED and UNBALANCED FISH POPULATIONS 53 BALANCED and UNBALNCED FISH POPULATINS 5 TABLE 18-B. Number 436 27,000 144 RECOVERED PER ACRE ON DRAINING, AUGUST 18, 1943 Species Pounds Large bluegills-----------------143.2 Small bluegills -------------- _-_------_---------------Intermediate largemouth bass _---------- 0 Small largemouth bass-------------------------------------- 0.0 Total --------------------------------------------------------------- 224.2 F/C =3.2, Y/C-=0.5, AT= 63.9, AF =84.1, SF =15.9 ----- -27.0 54.0 TABLE 19-B. RECOVERED PER ACRE ON DRAINING, AUGUST 18, 1943 Number 680 4,000 Species Pounds 288 0 Large bluegills_______________________-----------------------------143.0 Small bluegills ------------------------------4.0 Intermediate largemouth bass --0.0 0.0 Small largemouth bass ------------------------Total ------- ---------------------------------------- 207.0 F/C = 2.5, Y/C = 0.07, AT= 69.1, AF 97.3, SF = 2.7 TABLE 20-B. RECOVERED PER ACRE ON DRAINING NOVEMBER 7, 1944 Number 940 68 25,911 44 80 Species Large bluegills -------------Intermediate bluegills -------Small bluegills _.- Pounds ---------- -- 294.0 4.0 _---_---- Large largemouth bass Small largemouth bass Total------------------------------------------------------------- ---------- --------------------------------__ _--------------- 53.0 28.0 7.0 ---------- 386.0 F/C = 10.0, Y/G = 1.5, AT = 83.4, AF =83.8, IF = 1.1, SFi= 15.1 TABLE 21-B. RECOVERED PER ACRE ON DRAINING, NOVEMBER 7, 1944 Number 792 48 Species Large bluegills ________ Intermediate bluegills Pounds M_______ _______ __ 214.4 3.0 -_----------------------------------- 29,333 92 16 Small bluegills-------Large largemouth bass Small largemouth bass = Total -----------------------------------------------F/C =6.2, Y/C = 1.0, A 83.8, ----------AF = 82.0, --------------------------- __-----_----- 44.0 40.0 2.0 803.4 =1.1, IF Si = 16.9 54 ALABAMA AGRICULTURAL EXPERIMENT STATION 54Z TABLE 22-B. Number ALAAMA AGRICUTRLEPRMN TTO RECOVERED PER ACRE ON DRAINING, NOVEMBER 7, 1944 Species Pounds - 452 16,000 0 Large bluegills---------------------- 126. 67.0 Small bluegills-----------------------------20.0 112----------------------Large largemouth bass--------------Small largemouth bass ------------------------- Total -----------------------------------------------------------F/C.= 2.2, Y/C =0.3, AT =89.4, AF =84.6, --- 216.2 13.4 0.0 IF = 2.0, SF = TABLE 23-B. Number 1,368 RECOVERED PER ACRE ON DRAINING, NOVEMBER 7, 1944 Species Large bluegills Intermediate bluegills Pounds 0 280 256 0 -------------------------------- 250.8 ----------------------------- 0.0 Small bluegills ------------------------1.0 Intermediate largemouth bass -------------------- 48.0 ---------------------- 0.0 Small largemouth bass ----Total--------------------------------------------299.8 F/G = 5.2, Y/G = 0.02, AT = 88.7, A=99.6, S=0.4 TABLE 24-B. Number RECOVERED FROM 1.3 ACRES ON DRAINING, DECEMBER, Species Large bluegills ---Intermediate bluegills 1945 Pounds 777 1,950 ------------------ -------------------- 204.5 13.8--------------- 28,000 115 70 56.0 Small bluegills-------__--------------------------------------53.0 Large largemouth bass 9.5 _----------------------------Small largemouth bass 336.8 --------------------------------Total ---------- -----------------------------------AF= 74.6, IF FI/C=4.4, Y/C =0.9, AT =76.5, = 5.0, SFr = 20.4 TABLE 25-B. Number 991 9,446 42,828 105 2,634 RECOVERED PER ACRE ON DRAINING, JUNE 27, 1947 Species Pounds ____ _-----------------128.5 _-----_---_------------M------------------------ Large bluegills --------Intermediate bluegills Small bluegills -------------------------- Large largemouth bass Small largemouth bass ___---------------------------_-------------------------------- 78.1 160.6 66.2 24.3 T otal _ ----------- ----------------- 452.7 F/C =4.0, YIC= 1.8, AT =43.0, A= 7 35.5, IF = 20.2, SF =44.3 BALANCED and UNBALANCED BALANCED and UNBALNCD TABLE 26-B. FISH FISH POPULATIONS POPULATIONS 55 5 I RECOVERED FROM 2 ACRES ON DRAINING, OCTOBER 22, 1947 Number 501 Species Large bluegills Large shelicrackers Large largemouth bass ------__ Pounds __-___--- 51,297 271 107 Intermediate + small bluegills and shellcrackers_ Small largemouth bass _ Total--------------F/C = 3.7, AT = 162.0 389.0 102.0 601 -____________-150.0 ____26. _829.3 ____________ 49.9, Ar = 40.4, Ir + Sr = 59.6 TABLE 27-B. RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1946 Number 770 Species Large bluegills _-----___--------144.3 Pounds 1,188 87,215 880 32 4 Intermediate bluegills Small bluegills Large shellcrackers Total 206.8 ____ 22.3 91.5 Large largemouth bass ------ _575---____ Small largemouth bass--------_______ --------------------___ ----------------- _ 522.5 F/C = 8.1, Y/G = 3.6, AT = 56.1, Ar = 50.7,IF=4.8,SF=44.5 TABLE 28-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 25, 1948 Number 601 258 58,708 210 Species Large bluegills-----------------Intermediate bluegills Small bluegills---_------------------------Large shellcrackers ___--------_2 Pounds 74.1 213.1 2 21.0---_----___. 86.___ 38.3____ 553 200 109 30 Intermediate shellcrackers Small shellerackers Intermediate warmouth Large largemouth bass --------------------------------- 240 Total ----------------- ---- -- ----F/C =8.7, Y/C-=4.7, AT =33.2, AF ------Small largemouth bass---_____________------ ----- - ----------_--- __-__ --- 2.0 9.9 8---_-5.6 9.9 __ ---- 440.1 54.5 28.0, IFv= 17.5, SFr TABLE 29-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 26, 1948 Number 182 33 Species Large bluegills-----------------------____ Large shellcrackers ___------ Pounds ----__ _ 173 43,603 21 28 11 Intermediate bluegills and shellcrackers Small bluegills and shellcrackers Large largemouth bass Small largemouth bass Golden shiners AT = __--------_---- ------ 58.7 14.8 9.5 28.6 30.1 0.8 ---_----____4.1 _---____ Total-------------------------------------- -------= 146.6 F/C = 3.3, Y/C = 0.9, 70.7, AF = 65.4, I 8.4, SF= 26.2 56 56 ~ TABLE 80-B. Number 145 58 49,875 24 28 85 3 ALABAMA ALABAMA A;GRICUTRLEPRMN AGRICULTURAL EXPERIMENT STATION TTO RECOVERED PER ACRE ON DRAINING, DECEMBER 6, 1945 Species Pounds Large bluegills-----------------------------30.5 Large shelicrackers __________________21.0 Intermediate and small bluegills and shellorackers 99.8 Large largemouth bass_---- _2--9.--5 Small largemouth bass ----------- 8.0 Golden shiners ----------------------- 2.0 Goldfish, large --- --- --- --- --- --- -- - -- 6.5 Total-------------------------197.3 = F/C = 4.3, Y/C = 2.7, AT 44.8, AT =36.3,T +SFr=63.7 TABLE 31-B. RECOVERED PER ACRE ON DRAINING, DECEMBER 6, 1945 Number 593 Large Species bluegils ___________________________ ____ Pounds 1 . 1,478 5,704 2 27 85 40 593--Large-bluegills------------------------------118. Intermediate bluegills-----------84.0 --------- 107.0 Small bluegills ----------------Large shellorackers --------------------------- 1.0 Large largemouth bass _---------- --41.0 Small largemouth bass------_--_-_-- 20.5 Golden shiners ----- 20 _-____ 4.0 --------------------------- 0.3 Small green sunfish --------- 371.3 Total---------------------= F/C = 5.0, Y/C = 1.8, AT 41.9,AT=37.0,IF = 27.1, ST 85.9 TABLE 82-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 30, 1946 Number 877 19,440 124 25 Species Pounds ------------------------ 128.8 Large bluegills -----8-------8.8 Small bluegills -------------------------Large largemouth bass _---------------------------------Small largemouth bass--------------------5.5 52.3 80 Golden shiners---------------------------------------------Total 10.8 236.2 ------------------ --------------------------------------------- F/C =3.1, Y/C 83-B. =0.9, AT =76.7, AT =72.2, ST =27.8 OCTOBER 29, 1943 TABLE RECOVERED PER ACRE ON DRAINING, Number 776 45,500 285 Species Intermediate and small bluegills Pounds Large bluegills---------------------------------------------- 152.0 ------------------- 182.0 20.0 54.0 0.0 54 0 Golden shiners----------------------------------------- ----Large largemouth bass-----------------------------------Small largemouth bass Total--------------------------------------------------------F/C =6.6, ------------------------------- 408.0 AT = 50.5, AT= 42.9, IF+ Sp =57.1 BALANCED and UNBALANCED FISH POPULATIONS BALANCED and UNBLANCED FISH POPULATIONS OCTOBER 30, 1943 57 5 TABLE 34-B. RECOVERED PER ACRE ON DRAINING, Number Species Large bluegills Small bluegills Total Pounds r _____ ___-____-90.0 13,600 548 _126.0 186.0 2,126 40 Golden shiners Large largemouth bass---_- -- -_ ------_______ ___ ______------ 52.0 404.0 F/C = 6.8, Y/C = 4.3, AT = 44.1, Ar =85.8,Sr =64.2 TABLE 35-B. RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1, 1943 Number 708 23,800 Species Large bluegills Pounds ---- 625 92 Small bluegills Golden shiners Total -6.---0----------- --- --F/C =3.8, Y/C =2.7, Large largemouth bass -_--------- -----------238.0___ --238. _-100.0 _____146.0 ____ 100.0-------127.0 ---------Ai= 80.2, Sp =69.8 AT =44.7, TABLE 36-B. RECOVERED PER ACRE. ON DRAINING, NOVEMBER, 1942 Number 476 Species Large bluegills __-----Small bluegills------Golden shiners Pounds 86,963 90 88 Large largemouth bass __ F/C= --------- ------61.3, A -----------____ = -- _---_121.0 _-111.0 6.0 64.0 802.0 50.8, Si= 49.2 Total-------------------_---------------------------------- 8.7, Y/C = 1.8, AT = TABLE 37-B. RECOVERED PER ACRE ON DRAINING, DECEMBER 6, 1945 Number 1,170 Species Large bluegills Intermediate Pounds -----bass __---- _----__---- ________34.0 186.0 600 15,250 39 Small Large white crappie------------------------------ bluegills bluegills--45.8 8---------14.5 _.----- 15. 23 Small white crappie Large largemouth __----_------__------_-- - _ 3.0 ----18.5 0.0 0 Small largemouth bass Total--------------------------- _--------______ ___ F/C =8.1, Y/C =1.5, AT =72.6, AT= 69.2, I = 12.6, SF 301.8 = 18.2 58 ALABAMA AGRICULTURAL EXPERIMENT STATION 5,8 TABLE 38-B. ALABAA AGRIUTRLXPRMNSAIO RECOVERED FROM 1.3 ACRES ON DRAINING, DECEMBER, 1939 Number 1,657 8,200 88 188 4 235 Species Pounds Large bluegills----------------------------430.6 Small bluegills-----------------------------49.0 Large largemouth bass ----------------------- 68.8 Small largemouth bass --------------28.5 Large white crappie -------------------------- 4.5 Small white crappie -------------------------- 35.0 Total-------------------------616.4 F/C = 5.1, Y/C = 0.8, AT = 81.7, AF= 83.7, SF-= 16.3 TABLE 39-B. RECOVERED FROM 1.3 ACRES ON DRAINING, DECEMBER, 1940 Number 1,066 7,494 93 26 83 1 Species Large Small Large Small Large Small white crappie Pounds bluegills ----------------------------- 265.0 bluegills-------------------------39.0 largemouth bass---------------------- 35.3 largemouth bass-____----------------------white crappie ------------------------- 28.1 -------------------- 0.1 Total---------------------------369.6 F/C = 4.6, Y/C = 0.6, AT = 88.9, AF= 87.1, SF=12.9 1941 TABLE 40-B. RECOVERED FROM 1.3 ACRES ON DRAINING, DECEMBER, Number 716 Species Large bluegills-----------------Small bluegills .142.3 __ __-- Pounds 191.5 10.5 v24.0 59,887 57 83 40 0 Large largemouth bass----------36.8 Small largemouth bass___-------------------------------Large white crappie ----------Small white crappie _--------------------------------------Total--------------------------------------------------------------- - ------------------ 0.0 405.1 F/C =4.7, Y/C = 2.0, AT =62.3, AT =57.4, Sir= 42.6 NOVEMBER, TABLE 41-B. RECOVERED FROM 1.8 ACRES ON DRAINING, 1940 Number 601 Species Large bluegills Pounds ------------------------------------- 68.2 356,809 Small bluegills------_--------------------------------------- 41 2 579 Large largemouth bass-----------------------_____________38.1 Small largemouth bass Chub suckers--------------------------------------- 70.1 -------------------------------- 451 Yellow bullheads, intermediate------------------__________25.9 Total-------------------------------------------------------------- 264.9 =40.1, ------- 0.1 62.5 F/C =5.9, Y/C = 3.5, AT AT= 30.1, IF= 11.4, STF=58.5 BALANCED and UNBALANCED FISH POPULATIONS TABLE 42-B. RECOVERED FROM 1.8 ACRES ON DRAINING, NOVEMBER, 5 1943 59 Number 126 668 13,919 55 Species Large bluegills Intermediate bluegills -Small bluegills------------------88.9 Large largemouth bass _-----------43.5 _- Pounds -- ------- 2___-0.8-----______42.0 21 8 Small largemouth bass Yellow bullheads, large Total-------------- ------------------------_ ------------------------------------ 1.0 3.5 194.2 F/C = 8.4, Y/C = 1.9, AT = TABLE 48-B. 34.7, A = 15.9,I=28.1,S 56.0 RECOVERED PER ACRE ON DRAINING, DECEMBER 8, 1945 Number 245 851 14,032 Species Large bluegills Intermediate bluegills -------------------------_ Pounds 53.8 18.1 ___--------------- Small bluegills--------------------------49.0 26 72 17 Large largemouth bass------------------------25. Small largemouth bass----------------------- 13.1 Large yellow bullheads ------------------------ 7.5 Total---------------------------------------166.6 F/C = 3.3, Y/C = 1.8, AT = 52.0, AF = 47.8,I= 14.1, SF=88.1 TABLE 44-B. RECOVERED FROM 12.5 ACRES ON DRAINING, SEPTEMBER 27, 1949 Number 195 649 845 3,664 3,034 9,118 69,286 183 Species Pounds Large largemouth bass- _______________ ----491.45 Small largemouth bass ---------------------- 49.50 Large crappie (white) ---------------------- 245.40 Small crappie (white) ----------------------- 63.50 Large bluegills _----------------------------47.45 Intermediate bluegills shellcrackers 644.15 + Small bluegills + shellcrackers Large shelicrackers--------------------------------------- ------------------- ---------- 470.45 98.30 _0.20 7 8 F/C 2.50--------------Total ----------------------------------------------------------- 2,497.90 =2.1, Small yellow bullheads-------------------------------Large yellow bullheads -------Y/C = 0.7, AT = 50.8, Ai = 31.2, IF = 37.6, SF = 31.2 1940 TABLE 45-B. RECOVERED PER ACRE ON DRAINING, NOVEMBER, Number 1,574 Species Intermediate bluegills------------------------------------- Pounds 144.8 3,100 76 24 16 112 Small bluegills---------------------------------------------- 111.2 Large largemouth bass-------------------67.6 Small largemouth bass Large cats Large gizzard shad -_--------------------------------------- flathead ---------------------------------------- ------------------------------------ 160 Intermediate white crappie--------------------838.2 Intermediate yellow bullheads Y/C = 1.8 92.4 58.2 6 F/C =6.4, --------------------------- 1.6 = 41.4, SF = 24.9 Total----------------------------------------------------------- 515.8 1.6, AT = 42.3, AF =33.7, IF 60 TABLE 46-B. ALABAMA AGRICULTURAL EXPERIMENT STATION RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1941 Number 1,894 2,550 Species Large bluegills------________ 80 323 118 10 10 Intermediate and small bluegills Large largemouth bass -4---6.0 Small largemouth bass ----- -------------- ------ Pounds 808.0 80.0 Large white crappie Small white crappie Total--------------------------------- _60.0__-_ ------------------------ - 18.0 3.0 Yellow bullheads, small _.------- 0.4 515.4 F/C = 8.2, Y/G = 0.7, AT = 80.8, A =78.7,Ir+S=21.8 TABLE 47-B. RECOVERED PER ACRE ON DRAINING, OCTOBER 26, 1948 Number 780 643 46,299 Species Pounds Large bluegills-----------------------------132.4 Intermediate bluegills __-----------------------Small bluegills------------------------84.9 SGoldfish, 1 8 8 19 89 Buffalo, large ------------------------------ 1.5 ------------------ -4.4 2 Goldfish,-lrge--------Golden shiners------------------------------ 0.2 Large white crappie -------------------------Large largemouth bass ----------- --------34.4 Small largemouth bass 5.1 large ________________________ 4. 4.9 Total-----------------------------------------313.9 F/C=6.1,Y/C= 1.9, AT= 60.4, A =55.8,I= 12.6, S= = 81.6 TABLE 48-B. RECOVERED FROM 1.5 ACRES ON DRAINING, JANUARY, 1989 Number 268 7,880 76 Species Pounds Large bluegills--------------------------------------------- 65.4 Small bluegills---------------------------------------------- 178.6 Large largemouth bass------------------------------------ 124.2 846 2,858 8 Small largemouth bass ----------------------------------Golden shiners Yellow bullheads, large --- 76.6 5.8 _-____---------- _---184.7 ------------- 22 Gambusia Total __ -------------= 18.6, Sw = 81.4 _-w-_-_0.8 __580.1 F/C =1.9, Y/C = 1.5, AT = 83.6, Ai BALANCED and UNBALANCED FISH POPULATIONS 61 BALANC~bEDlg and UNBLACEID TABLE 49-B. FSH PPULTIONS 6 RECOVERED FROM 29 ACRES ON DRAINING, OCTOBER, 1940 Number 2,215 826 8,434 22 Species Large bluegills Large shelicrackers __-----Small bluegills + shelicrackers Large largemouth bass _--_--_--------- Pounds -255.4 ---------------- 25.0 ----- 471.0 140.5 71 2,282 Large largemouth bass Small largemouth bass __------------ ----- 220.0 95 83 59 Warmouth, large ---------------------------- 11.0 Suckers (spotted), large---__--___--124.4 Speckled bullheads, large ___ --------------------- 73.7 Total---------------------------1,392.0 F/C = 2.2, Y/G = 0.06, AT = 82.4,AF= 97.4, SF=2.6 TABLE 50-B. RECOVERED FROM 25 ACRES ON DRAINING, NOVEMBER, 1939 Number 1,697 1,500 388,350 810 3,500 9 27 1 1 Species Pounds Large bluegills----------------------------447.1 Intermediate bluegills ----------------------- 300.0 388,350 Small-buegi--s---------------------------579. Large largemouth bass ----------------------- 598.4 Small largemouth bass _______________----8.8 Warmouth, large ----------------------------2.0 Yellow bullheads, intermediate------------------- 5.6 Speckled bullhead, large-------------------2.6 Spotted sucker, large --------------------------------- 4.2 Total--------------------------------------1,948.3 Small bluegills ,___________________ 579.6_ F/C = 2.2, Y/C = 1.0, AT = 54.1, A = 84.0,I=22.8,S=43.2 TABLE 51-B. RECOVERED EROM 4.75 ACRES ON DRAINING, JUL~Y, 1940 Number 803 12,245 93 139 Species Pounds Large bluegills---------------------------------------------- 76.6 Intermediate and small bluegills---------------__________210.5 Large largemouth bass------------------------------------ 86.8 Small largemouth bass-_--------------------------------1. 23 106 Large white crappie------------------Small white crappie -_--_--------------------------5.5 ---- 11.8 7.8 11.8 1.0 28 644 14 34 Large warmouth ---------------------------Small warmouth ---------------------------------------Large speckled bullheads Small speckled bullheads _---------------------------18.9 3 85 148 Yellow bullheads, large -----------------------------------Chub suckers-----------------------------------------------Golden shiners -------------------------- 3.1 18.5 ----------- Total ------------------------------------------------------- ----------------------------------- 1. 479.2 F/C = 3.2, Y/C =2.3, AT =42.3, AT =28.8, IF + Sr=71.7 62 ALABAMA AGRICULTURAL EXPERIMENT STATION 62 TABLE 52-B. ALABAMA AGRICUTRLEPRMN TTO RECOVERED FROM 2.3 ACRES ON POISONING, SEPTEMBER 4, 1948 Number 199 Species Large bluegills _ _____2-_ Pounds 28.3 2,312 1,052 237 Intermediate bluegills Small bluegills Large shellcrackers 92.5 6.1 0.4 62 4 5 2 5 6 5 11 4 5 80 2,223 3,947 306 481 41 34 Intermediate shelicrackers _ -5.0 Small green sunfish -_-Small stump knockers __ Large speckled bullheads Small speckled bullheads __Large carp _--82.0____-_ _ -. _ _ _Large buffalo-----------------____54.0 Large spotted suckers _-23.5 Large long-nose gar __ Large eels -- -- -- -- - -- - --- -- - - --Large gizzard shad __----Intermediate gizzard shad------------------Small gizzard shad -------_ ________ -_-- - 0.3 3.-__8 0.1 2 10.4 --- - - - -180.0 --- 1.4 211.5 62 Large black crappie --- - ---Intermediate black crappie _ Small black crappie ----------------Large largemouth bass --------------- 39.9-66.6 -_--- 57.0 0.4 82.6 Small largemouth bass Total ----- ---------------- _--------------- 2_--.1 979.9 18.99 F/C = 5.1, Y/C = 0.3, AT = 57.9, A' = 22.2, AT=35.7,Ar=75.8,IF SF = 5.3 TABLE 53-B. RECOVERED FROM 3 ACRES ON POISONING, OCTOBER 21, 1949 Number 40 124 Species Large spotted bassSmall spotted bass 3 8 Large largemouth bass -----------------------------------Small largemouth bass ------------------------------------- --------- Pounds 15.19 5.19 26 475 1 26 126 Large bluegills ------------------Small bluegills ------------------------------------------Large warmouth----------------------------------------Small warmouth Small green sunfish ----------- 1.61 1.25 _------------------------ 45 4 26 --------------------------------------Large spotted sucker----_----_----- --------Small long-ear sunfish ---------------Orange-spot sunfish, small ---- 8-------------------.94 7.25 0.38 1.00 _---------------------0.13 ------- 35.50 0.31 0.13 1 178 78 18 Small shellcrackers --------------------------------------- 0.06 Log perch, small -------------------------------- --__0.75 Small white crappie Large channel cats _------------------------------ ---------------- _-------------_---- _- 125 1 2 1 379 Inetrmediate and small channel cats-------------_______-7.50 Large flathead cat --___------------ --------------------------------------______ 1.75 5.38 Small cats ------Carp, large--------------------------------8-----------M innows _ __--------------_ Total ---------------------- --------------------------------- flathead ------ 1.00 .88 2.07 94.40 0.13-------- --- -------- F/C = 3.1, Y/C =0.6, AT = 70.4, A = 70.4, I = 11.5, Sir= 19.1 BALANCED and UNBALANCED FISH POPULATIONS TABLE 63 3, 1949 54-B. RECOVERED FROM 5 ACRES ON POISONING, SEPTEMBER Number 188 624 Species Large largemouth bass Small largemouth bass ___ __---------- Pounds 146.8 __ _ 105 81 Large white crappie Small white crappie Large 584 3,053 23,450 712 bluegills-102.9 ____-------02. Intermediate bluegills ___ ------------------------ 16.6 Small bluegills and shellcrackers (1")_-----2.4 Large shellcrackers __ _---_______ ----------- - - - - 41.4-----5.0 12.5 900 21 266 139 336 59 40 1 186 134 3 20 83.1 49.1 2.0 Large warmouth -9.--0 Intermediate warmouth ----------------------- 11.9 Small warmouth ----- ________ 1.0 Large speckled bullheads -_-56.0 Small speckled bullheads 2.4 Round flier, large ___ ---0.1 Intermediate shellcrackers Intermediate green sunfish_-- -- -------------------- --- ----------- Large gizzard shad Small gizzard shad Carp, large 223.0 ---------____-- -- ------------- 5.5 --. 26.0 29 20 21 43 Suckers (spotted), large _----_---Eels, large -------- ---------------Bowfin, large Gar, large __-----w--------45 ------ 14.5 Golden shiners T otal ------------------- ___ -- F/C = 2.7, Y/C = 0.07, AT = 78.8, AT = 44.3, S = 2.2 AT -34.5, Air= 72.5, IF 44.__-,48 45.01.2 0-1----7--=25.3, TABLE 55-B. RECOVERED PER ACRE ON DRAINING, NOVE~MBER, 1939 Number 986 Species Large bluegills------ Pounds 265.0 0 15,222 20 65 Intermediate bluegills Small bluegills Large largemouth Small largemouth bass ----------bass = _----------------- ___ 0.0 ___ ___---_---__---_---- ---2.2 12.8 39.0 35.2 Total-----------------F/C =8.1, Y/C = 1.0, 341.4 87.2, AT 87.9, A= 1 S1 = 64 ALABAMA AGRICULTURAL EXPERIMENT STATION 64 TABLE 1-lj. ALABAMAI AGRCLURLEPEIET RECOVERED PER ACRE ON DRAINING, SEPTEMBER TTO 29, 1949 Number 304 420 51,028 56 124 F/C Pounds Large bluegills _______________________5.0 Intermediate bluegills -----------------------18.0 Small bluegills--------------------312.4 Large largemouth bass----------------91.0 Small largemouth bass ------------------------ 3.8 Total---------------------------------------480.2 = 4.1, Y/C = 3.3, AT = Species 30.4, Air=14.3, IT 4.7, Sr = 81.0 TABLE 2-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 5, 1949 Number 48 212 60,864 28 8 Species Pounds Large bluegills------------------------------9.0 Intermediate bluegills-_ _____----------------7.2 ----------- 350.0 Small bluegills --------------------------------------- 52.0 Large largemouth bass---------------------- 0.2 Small largemouth bass ---------18.4 Total ---------------------- ---------------------AT = F/C = 7.0, Y/G = 6.7, 14.6, AT =2.5,I=2.0, ST=95.5 TABLE 3-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number 56 256 142,740 20 0 Species Pounds 12.2 Large bluegills ---8.2 Intermediate bluegills__------------------------------------285.5 Small bluegills-_____---------------89.0 Large largemouth bass 0.0 -------------------------------Small largemouth bass 44.9 ---------_______--Total - ----------------------- -- -----------------------------_-8--------- ----- F/C =7.8, Y/C =7.3, AT = 14.8, AT = 4.0, IT =2.7, ST = 93.3 TABLE 4-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number 8 176 44,480 Species Large bluegills Intermediate bluegills Small bluegills Pounds ---------___-___-__ _------- ------ ---_--------5.0 _--- 8.8 24 328 Large largemouth bass Small largemouth Total bass___ _ ___ -----_---_---216.8 45.0 26.2 ---- _ _ ____-------- -- _----301.8 F/C-= 3.2, Y/C =3.0, AT = 16.6, AT =2.2, Iw= 3.8, ST =-94.0 BALANCED. BIALANCEDand and UNBALANCED UNBLANCED FISH FISH PPULATIONS POPULATIONS 65 6 TABLE 5-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 8, 1949 Pounds Number 8 748 108,820 Species Large bluegills -------------------------Intermediate bluegills __________-------Small bluegills ----------------------------- 44 0 Large largemouth bass --Small largemouth bass Total _----- 28.8 --808.8 -------------------- 84.0 --_----- --------- 4.2 ---------------------------------- -- 0.0 425.8 F/C = 4.1, Y/G = 8.7, AT = 20.7, A1 = 1.2,Iip=8.4,51=90.4 TABLE 6-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 6, 1949 Number Species Pounds _-___- 532 788 Large bluegills - 119.2 299.3 Intermediate bluegills -46.2 31,928 82 168 Small bluegills Large largemouth bass4. Small largemouth bass Total ----------------------- __ _____ ----- _----_ 299.3____ 45.0 ------- 4.3 514.0 F/C = 9.4, Y/G = 6.1, AT = 31.9, Ai = 25.7,IF=9.9,S5 =64.4 TABLE 7-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 8, 1949 Pounds Number 24 Species Large bluegills Small bluegills 1,184 102,980 Intermediate bluegills Large largemouth bass-__ Small largemouth bass Total - -_-------___--____471.7 ------- 32 0 55.0 8------_ 54.2 54.5 --0.0 8.0 F/C = 7.7, Y/C =6.5, AT = 13.2, A1 1.9,16 =18.2, Sp 84.9 TABLE 8-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 4, 1949 Number 286 556 Species Large bluegills Small bluegills Total______________ ___________ ____________ - Pounds 69.5 16.2 Intermediate bluegills-___________ Large largemouth bass Small largemouth bass 51,740 56 0 301.8 62.0 0.0 _-449.5 F/C =6.3, Y/C =4.9, AT =29.3, A1 = 17.9, 11=4.2, S =77.9 66 ALABAMA AGRICULTURAL EXPERIMENT STATION 66 TABLE 9-U. ALAAMA AGRCUTRLEPRMNSAIO RECOVERED PER ACRE ON DRAINING, AUGUST 18, 1943 Number 760 87,600 20 86 Species Large bluegills -----------------------------Small bluegills----------------------300.0 Pounds 92.0 Large largemouth bass ------Large largemouth bass-----Total -------------------------------------------- ----------------- 38.0 ----------------- 36.0 466.0 F/C = 5.3, Y/C = 4.1, AT = 85.6, Ai =28.5,SF =76.5 TABLE 10-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 80, 1946 Pounds Number 805 17,400 27 40 Species 89.8 Large bluegills----------_235.3 Intermediate and small bluegills ---------------- 33. Large largemouth bass --------------------------- 1.5 Small largemouth bass-------309.9--------------Total I+S=85.5 F/C =7.9, AT = 23.6, A= 14.5,I TABLE 11-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 30, 1946 Number 415 15,981 15 100 Species Large bluegills Intermediate and small bluegills Large largemouth bass _ Small largemouth bass w---Total -------------- Pounds ---------------------------- -----------Sp ____---_ _---_61.8 ----_ --16.5 7.0 293.0 ----378.3 F/C = 15.1, AT = 20.7, A, = 17.4, I + =82.6 TABLE 12-U. RECOVERED PER ACRE ON DRAINING, NOVEMBER 11, 1944 Number 0 11 18 Species Large green sunfish Small green sunfish ___--------Large largemouth bass ___-Small largemouth bass _________3.8 ------------ Pounds 0.0 0.0 12.8 0 Intermediate green sunfish--------------------1.0- 85 Total--- -- 17.6 0,I, =100.0, S,=0 F/C = 0.06, Y/C = 0.0, AT ='72.7, A, = BALANCED and UNBALANCED FISH POPULATIONS 67 ALACED and UNBALANCED FISH POPULATIONS TABLE 18-U. RECOVERED PER ACRE ON DRAINING, OCrOBER 25, 1948 6 Number 601 258 58,708 210 553 200 Species -Large bluegills Intermediate bluegills Small bluegills ------- _213.1 Large shellcrackers -3--6.-----362 Intermediate shelicrackers Small shellcrackers _____________ ____ _- _ _9.9 Pounds 7 74.1---- 21.0 38.3 2.0 109 30 240 Warmouth, intermediate Large largemouth bass Small largemouth bass Total 35.6 9.9 __-------------------.--------440.1 F/C = 8.7, Y/G = 4.7, AT = 33.2, AT = 28.0, I, 7.5, Sir=54.5 TABLE 14-U. RECOVERED FROM 2.6 ACRES ON DRAINING, OCTOBER 28, 1948 Number 641 Species Large bluegills Pounds 76.9 _______- 6,977 219 Intermediate bluegills Large shelicrackers 402.4 30.4 128.3 130.6 7.0 4.3 11.0 1.3 A,01--------- 80,725 2,482 241 113 2 21 Small bluegills Intermediate green sunfish Large speckled bullheads Small speckled bullheads Large largemouth bass Large smalimouth bass Total + shellcrackers -220.4 ____ _ ----------------- F/C= 65.1, Y/C = 14.9, AT = 25.0, A = 23.9, I, = 53.3,S5, = 22.8 TABLE 15-U. RECOVERED FROM 1.3 ACRES ON DRAINING, OCTOBER 24, 1947 Number 764 13,860 Species Intermediate bluegills-----------____ Small bluegills Pounds 57.8 ------ ----w-- ----- - 41 Large black crappie 4,196 318 Intermediate black crappie Small black crappie ~----____ _______ __219.0 12.6 275.4 4.7 43 68 Large largemouth bass---__-53. Small largemouth bass __________.__2.8 __________626.2 Total 8.0, Y/C =3.2, AT = 10.6, A,-= 0.0, I, =59.8, F/C Sr = 40.2 68 ALABAMA AGRICULTURAL EXPERIMENT STATION 68 TABLE 16-U. ALABAMA AGRIUTRLEPRMNSAIO RECOVERED PER ACRE ON DRAINING, OCTOBER 26, 1948 Number 73 154 661 56 Species Large Pounds shelicrackers _____ --------------------------20.4 Intermediate shelicrackers_---------------------1 Small shellcrackers _12.4 Large bluegills Intermediate bluegills--------- 275 -------- ---- 15.4 11,559 11 50 Small bluegills-----Large largemouth bass Small largemouth bass ------------------__158.5 --------__------------0.9 -- --- 18.8 19.8 50.8 1,202 Golden shiners Total -------------------= 13.9, Y/C --------- -_------12.5,IF=10.7, 808.6 F/C = 10.7, AT = 18.0, AF= S=76.8 TABLE 17-U. RECOVERED PER ACRE ON DRAINING, DECEMBER 6, 1945 Number 11 Species Large shellcrackers Intermediate shellcrackers Small shellcrackers _ Pounds __ ---- 14 8,187 80 7 3,691 81 51 104 Large bluegills Intermediate bluegills Small bluegills _______58.6 Large largemouth bass Small largemouth bass Golden shiners Total______-______171.1 _8.5 ------ 8.1_____ 0.8 35.7 1.4 1___ .7 - - 81.0 15.3 F/C =2.7, Y/C =2.2, AT = 29.5, AF= 15.6, IF =2.0,S5,= 82.4 TABLE 18-U. RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1948 Number 880 1,720 12,500 112 Species Large bluegills-__--------_____ Intermediate bluegills __ Small bluegills and shellcrackers Large shelicrackers ________ __- Pounds 62.0 52.0 254.0 28.0 512 48 872 4 Total ___- Intermediate shellcrackers Large largemouth bass Small largemouth bass __ Large yellow bullheads -_____________521.0 __ __ _____4.0 22.0 56.0 43.0 F/C =4.8, Y/C =2.6, AT = 28.8, Am= 22.8,I= 17.5, SF = 60.2 BALANCED and UNBALANCED FISH POPULATIONS BALNCED and- UBALNCED FISH POPULTIOS 69 6 TABLE 19-U. RECOVERED PER ACRE ON DRAINING, OCTOBER 26, 1948 Number 200. Species Large bluegills Pounds 1,859 4,284 10 22 1 Intermediate bluegills Small bluegills Large largemouth bass ------- -8--------1.5-----8 _------------.5 _----------_____ 63.1 84.7---------144-----------14 245.2 =37.0 Small largemouth bass ______ White crappie, large---- ____1.0 Total ------------------------------------------------------AT = F/C = 14.4, Y/G = 5.3, TABLE 20-U. 32.0, Ai = 27.5,IF=35.5,SF RECOVERED FROM 2.2 ACRES ON DRAINING, NOVEMBER 5, 1948 Number 501 149 Species Large bluegills Intermediate bluegills ______- Pounds 61.4 8.9-8 229.7----__ 435.5 175,024 3,522 Small bluegills Small green sunfish ---------------__ ____2 --- 4,537 Intermediate speckled bullheads 20 1 69 43 Small speckled bullheads Large goldfish __---- Large largemouth bass Small largemouth bass Total ------------------------ -- __45.6 _____ 1------------0.5 8.3 864.7 _74.7 F/C = 9.4, Y/C = 3.3, TABLE 21-U. AT = 15.8, AF = 7.9,IF=56.9,SF=85.2 RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1948 Number 38 Species Large bluegills -----Small bluegills -------. ____________ -- Pounds 1--7.---1--- 3,689 4-----1 27 134 Large green sunfish Small green sunfish 4.4 2.4 3__ 1.6 31 1,085 Large largemouth bass Small largemouth bass Total---------_------ 31.4 _______________91.0 ---AT F/C = 0.4, Y/C =0.08, TABLE 22-U. =58.4, AF =76.8,1I6 0.0, SFp 23.2 Pounds 44.6 RECOVERED FROM 2.1 ACRES ON DRAINING, NOVEMBER 10, 1948 Number 232 298 Species Large bluegills_ Intermediate bluegills ---------------------- _--______----23.0 45,797 Small bluegills--------------------------540.0 15 7 1,764 49 20 Large green sunfish -----------------------------------Intermediate green sunfish---------- _-----_ Small green sunfish _--------_____-------21.0 Large largemouth bass __---------------Intermediate largemouth bass 3.3 0.5 87.8 6.0 -----------_ _ ________------ 71 Small largemouth bass Total------ -- _ 2.7 728.9 = -------AT = ---------- F/C = 6.6, Y/C = 5.8, 18.6, A 1 = 7.6, II= 3.7, S1 88.7 70 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 28-U. RECOVERED PER ACRE ON DRAINING, OCTOBER, 1948 Number 356 Species Small bluegills___---------------------------------_------ Pounds Large bluegills-------_-----------------------------56.4 19,546 92 8,124 8 Large gizzard shad _-------------677.2 Intermediate gizzard shad--_--------Large largemouth bass __--------------------------------- ----------------------------------- -- 248.4 81.2 16.4 Total ------------------------------------------------------F/C = 64.8, Y/C = 15.2, AT = 14.2, AT= SF = 28.4 1,079.6 6.7, AT=7.5,AFr=12.9, IF=63.7, TABLE 24-U. RECOVERED PER ACRE ON DRAINING, NOVEMBER 16, 1943 Number 620 Species Large bluegills Pounds 16,500 136 2,360 Small bluegills Large largemouth bass _-__------_____ - --------__ _ - ----------____----- 107.0 ------------- Intermediate gizzard shad Total AT =26.3, --- --------------- ----------- ______66.0 101.0 --_------- 516.0 790.0 F/C = 6.8, Y/G =0.7, TABLE 25-U. AT = 15.5, IF = 74.9, SF = 9.6 RECOVERED PER ACRE ON DRAINING, OCTOBER 22, 1948 Number 288 29,224 24 Species Large bluegills Small bluegills ------------------------- Pounds 41.2 196.8 __----------------_ Large gizzard shad ------- 16.0 1,672 16 Intermediate gizzard shad Large largemouth bass --T otal ____ ___ ______ 494.0 _____________ __- _____------_---__----_---40.0 ------- F/C= 18.7, Y/C = 4.9, ------788.0 AT = 12.3, AF= 7.6, IF= 66.1, SF =26.3 TABLE 26-U. RECOVERED FROM 2.2 ACRES ON DRAINING, NOVEMBER 18, 1949 Number 982 625 30,336 98 Species Large bluegills ----Intermediate bluegills ---------- Pounds 269.8 51.7 Small bluegills___ Large warmouth 509.3 21.4 _ 113 7,784 132 6 - ___--------___Intermediate warmouth -Small warmouth _________ Large Eastern pickerel Small Eastern pickerel Total ------------- 13.2 88.0 128.7 ------____----1.0 1,083.1 =62.7 F/C =7.4, Y/C =4.6, AT = 38.8, AF =30.5, IF = 6.8, Sp BALANCED and UNBALANCED FISH POPULATIONS 71 BALANCED and UNBALANCED TABLE 27-U. FISH POPULATIONS 7 RECOVERED PER ACRE ON DRAINING, SEPTEMBER 29, 1949 Number 160 692 49,060 116 64 0 Pounds Large bluegills ----------------------------- 4.5 Intermediate bluegills ------------------------- 29.0 Small bluegills-----------------------------276.0 Small warmouth-----------------------------4.5 Large largemouth bass ------------------------ 95.2 Small largemouth bass -- - ------------------------- 0.0 Total----------------------------------------------------439.2 = Species F/C = 8.6, Y/C = 2.9, AT 29.5,AT=10.0 I,= 8.4, S =81.6 TABLE 28-U. RECOVERED PER ACRE ON DRAINING, NOVEMBER, 19,q8 Number 2,278 2,368 184 12,472 Species Pounds Intermediate bluegills ----------------------- 108.8 Small bluegills------------------------------3.2 Intermediate white Crappie ----16.8 Gambusia-------------------------------------88.4 Total---------------------------------167.2 F/C= oo AT=0.0 TABLE 29-U. RECOVERED PER ACRE ON DRAINING, NOVEMBER, 1939 Number 0 2,016 23,816 144 16,968 Species Pounds Large bluegills-----------------------------0.0 Intermediate bluegills --------------------- 156.8 --------Small bluegills----------------------__-----152.8 Large white crappie ------------------------- 58.4 Small 8,820 16 8 Gambusia---------------------------------------Chub suckers, large ----------------- -white AT crappie--------------------------------------- 72.0 2.4 ----- 11.2 4.8 --- Yellow bullheads, large------------------------------------- Total--------------------------------------------------------------- 458.4 F/C.= 6.8, Y/C = 4.0, =14.8, Ar - 1.8,IT==39.2, S = 59.0 TABLE 30-U. RECOVERED FROM 1.2 ACRES ON DRAINING, DECEMBER, 1938 Number 29,778 53 240 Species Pounds 44. --------------------287 Larebueill-------Intermediate + small bluegills ------------------ 124.5 Large white crappie--------------------------------------- 24.9 Small white Total 5,023 Gambusia---------------------------------------------------- crappie ----------AT = _______-----.------------------------------------ --- 19.0 -------------------------- 16.8 229.7 F/C =8.2, Y/C =6.4, 80.2, AF = 21.7, I + SF =78.3 72 ALABAMA AGRICULTURAL EXPERIMENT STATION 72 TABLE 31-U. ALABdAMnA AGRCLURLEPEIET TTO RECOVERED FROM 1.2 ACRES ON DRAINING, DECEMBER, 1939 Number 0 2,462 15,554 17 118 2,368 10,397 Species Large bluegills -------------------- Pounds --0.0 114.6 229.6 22.4 -52.6 Intermediate bluegills --------Small bluegills ----------------Large white crappie ------Intermediate white crappie -13.4 Small white Crappie ---------Gambusia-14.7 Total-447.3 AT F/C = 19.0, Y/G = 13.2, = 5.0, AF=0.0,IF =30.1, SF=69.9 TABLE 32-U. RECOVERED FROM 1.8 ACRES ON DRAINING, DECEMBER, 1937 Number 4 0 8 20,696 Species Large largemouth bass ------------------------Small largemouth bass --------------------------L arge bluegills Small bluegills --------------------------------------.-------------------------- Pounds 12.4 0.0 3.4 79.2 8 3,849 10 Large white crappie --------------------------Intermediate white crappie --------------------Large yellow bullheads ------------------------- 10.6 32.2 8.8 668 4 277 3 630 Small yellow bullheads ------------------------ 62.3 Large blue cats ------------------------------ 13.1 Chub Suckers --------------------------------- 15.5 Goldfish, large -- ---- --------------------------2.5 Gambusia --------------2.0 T ota l - - --- - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - --- 242 .0 -AT =21.0, F/C-= 9.5, Y/C =6.9, AF - 12.7, IF - 14.7, SF = 72.6 TABLE 33-U. RECOVERED FROM 1.8 ACRES ON DRAINING, DECEMBER, 1938 Number 13 11 5,661 21,670 5 1,392 0 493 4 50 2 3,017 Species Pounds Large largemouth bass ------------------------ 43.7 L arge bluegills ---------------------------------3.8 Intermediate bluegills--------------------------- 125.9 Small bluegills ---58.4 58.4--Large white crappie ---4.1 Intermediate white crappie 42.8 0.0 Small white crappie ---------Small yellow bullheads -----82.0 Large blue cats ------------- --14.6 Chub suckers, small -------------4.3 Goldfish, large -- - - -- - - - -- - - -- - - -2.8 Gambusia --2.8 Total-385.2 AT = F/C = 7.1, Y/C = 3.1, 17.9, AF =6.3,IF 50.0,SF=43.7 BALANCED and UNBALANCED FISH POPULATIONS 73 TABLE 34-U. RECOVERED FROM 1.8 ACRES ON DRAINING, DECEMBER, 1989 Number 9 1 28 4,093 25,620 8 1,707 0 212 141 4 0 956 Species Large largemouth bass ----------------------Small largemouth bass -----------------------Large bluegills -----------------------------Intermediate bluegills -----------------------Small bluegills --------------------------Large white crappie ----------------------Intermediate white crappie --------------------------------------------Small white crappie Large yellow bullheads ---------------------Small yellow bullheads -----------------------Chub suckers -----------------------------------------------Goldfish -------------------------------------------------------------------------------------Gambusia Total ------------------------------------------------------------ Pounds 43.5 0.2 7.8 188.9 49.9 10.4 66. 0.0 100.1 8.9 0.1 0.0 1.8 477.9 F/C = 7.8, Y/C = 1.1, AT = 33.9, AF = 25.5, IF = 60.2, SF = 14.8 74 ALABAMA AGRICULTURAL EXPERIMENT STATION OTHER AVAILABLE PUBLICATIONS BULLETIN NO. 254. Management of Farm Ponds. H. S. Swingle and E. V. Smith; 32 pages illustrated. One of the chief reasons for failure of ponds to yield good fishing is the lack of understanding of the principles underlying management of water areas. Based on their research, the authors explain the principles of good management, proper stocking, managing old ponds, fertilizing, fishing, and controlling weeds and mosquitoes. BULLETIN No. 264. Experiments on Pond Fertilization. H. S. Swingle; 36 pages. This is a technical bulletin that reports results from many experiments, and includes: variations of plankton growth, factors determining algal production, surface scum and dispursed growth of plankton algae, phytoplankton pulses, delayed algal growth, carbon dioxide as limiting factor in fish production, fertilizer treatments involving organic and inorganic materials, and clearance of muddy waters. CIRCULAR NO. 87. Factors Affecting the Reproduction of Bluegill raising fish in ponds is managenumber reaches desirable size found in experiments conducted of bluegills and black bass are Bream and Largemouth Bass in Ponds. H. S. Swingle and E. V. Smith; 8 pages. One of the principal problems involved in ment of population, so that a maximum each year. Some of the factors that were by this Station to affect the reproduction summarized in this circular. CIRCULAR No. 95. Construction of Farm Ponds. John Lawrence; 56 pages illustrated. This publication gives the step-by-step methods for building a farm pond, including: water supply, depth requirements, determination of pond area, construction details of dam, how to protect dam from breaks, filling the pond, and measures for mosquito control. LEAFLET NO. 20. Ponds for Improving Stream Fishing. E. V. Smith and H. S. Swingle; 8 pages illustrated. Construction and proper management of ponds on small streams appear to offer the best method of immediately improving stream fishing. The authors tell how ponds restock streams, increase food supply of streams, reduce fishing pressure on streams, and prevent silting of stream channel. LEAFLET NO. 22. Raising Crickets for Bait. H. S. Swingle; 4 pages illustrated. The necessary equipment and methods for raising crickets in the garage, basement, or vacant room are given in detail in this publication. PROGRESS REPORT SERIES NO. 5. Raising Fishworms for Bait. H. S. Swingle and D. G. Sturkie; 4 pages. The authors tell how a supply of fishworms can be maintained in the garage, basement, or outdoor worm bed. Free copies of the above publications may be obtained by writing the DIRECTOR, ALABAMA AGRICULTURAL EXPERIMENT STATION, Auburn, Ala. Order by number or title.