Bulletin ILLINOIS NATURAL HISTORY SURVEY BUllCttTl ^"'»"'' *> Authority of ffgl the State of Illinois Hook-and-Line Catch in Fertilized and Unfertilized Ponds DONALD F. HANSEN GEORGE W. BENNETT ROBERT J. WEBB JOHN M. LEWIS STATE OF ILLINOIS • WnxiAM G. Stratton, Governor DEPARTMENT OF REGISTRATION AND EDUCATION • Vera M. Binks, Director NATURAL HISTORY SURVEY DIVISION • Harlow B. Mexs, CAiV/ MATtiD&l ILLINOIS NATURAL HISTORY SURVEY Bulletin Volume 27, Article 5 . , , . , Printed by Authority of August, 1960 '^^ State of Illinois Hook-and-Line Catch in Fertilized and Unfertilized Ponds DONALD F. HANSEN GEORGE W. BENNETT ROBERT J.WEBB JOHN M. LEWIS STATE OF ILLINOIS • William G. Stratton, Go'vernor DEPARTMENT OF REGISTRATION AND EDUCATION • Vera M. Sinks, Director NATURAL HISTORY SURVEY DIVISION • Harlow B. Mills, Chief Urbana Illinois STATE OF ILLINOIS Wii.iiAM G. Stratton. Goz'i'rnor DEPARTMENT OF REGISTRATION AND EDUCATION Vera M. Binks, Dirfclnr BOARD OF NATURAL RESOURCES AND CONSERVATION Vera M. Sinks. Chairman: A. E. Emerson. Ph.D.. Biology; Walter H. Newhouse, Ph.D.. Geology ; Roger Adams, Ph.D.. D.Sc, Chemistry ; Robert H. A.nderson, B.S.C.E., Engineering: W. L. Everitt, E.E.. Ph.D.. Representing ihr President of the University of Illinois; Delyte W. Morris, Ph.D., President of Southern Illinois University NATURAL HISTORY SURVEY DIVISION, Urbana, Illinois SCIENTIFIC AND TECHNICAL STAFF Harlow B. Mills, Ph.D., Chief Bessie B. East, M.S., Assistant to the Chief Section of Economic Entomology GtoRCE C Decker, Ph.D., Principal Scientist and Head J. H. Bigger, M.S., Entomologist L. L. English, Ph.D., Entomologist \\. H. Llckmann, Ph.D., Entomologist Willis N. Bruce, Ph.D., Associate Entomologist John P. Kramer, Ph.D., Associate Entomologist Ronald H. Meyer. M.S., Assistant Entomologist Richard B. Dysart, B.S., Assistant Entomologist Eugene M. Bravi, M.S., Research Assistant Roy E. McLaughlin, B.S., Research Assistant Reginald Roiierts, A.B., Technical Assistant Iames W. Sanford, B.S., Technical Assistant Earl Stadelbacher, B.S., Technical Assistant William C. Moye, M.S., Technical Assistant WE E. Watkins. Technical Assistant H. B. Petty, Ph.D., Extension Specialist in Entomology* Stevenson Moore, III, Ph.D., Extension Specialist in Entomology* Zenas B. Noon. 1r., M. S., Research Assistant* Clarence E. White, B.S., Instructor in Entomology Extension* CosTAs KousKoi.EKAs, M.S.. Research Assistant* Amal Chandra Banerjee, M.S., Research Assistant* Section of Faunlstic Surveys and Insect Identification II. II. Ross, Ph.D., Systematic Entomologist and Head MiLioN W. Sanderson, Ph.D.. Taxonomist Lewis J. Stannard. Jr., Ph.D., Associate Taxonomist Philip W. Smith. Ph.D., Associate Taxonomist Leonora K. Gloyd, M.S., Assistant Taxonomist H. B. Cunningham, M.S., Assistant Taxonomist Edward L. Mockford, M.S.. Technical Assistant Tiielma n. OvERSTREET. Technical Assistant loiiN M. KiNcsoi.VER. M.S., Research Assistant Tai.aat K. !\fiTRi. M.S.. Research Assistant* Section of Aquatic Biology George \V. Bennett, Ph.D., Aquatic Biologist and Head William C. Starrett. Ph.D., Aquatic Biologist R. W. Larimore, Ph.D., Aquatic Biologist David H. Buck, Ph.D., Associate Aquatic Biologist Robert C. Hiltibran. Ph.D., Associate Biochemist Donald F. IIansln, Ph.D., Associate Aquatic Biologist William F. Chii.ders, M.S., Assistant Aquatic Biologist Marifran Martin, Technical Assistant Robert D. Crompton, Field Assistant Larry S. Goodwin, Laboratory Assistant Arnold W. Fritz, B.S., Field Assistant* Section of Aquatic Biology—continued David J. McGinty, Field Assistant* Charles F. Thoits, III, A.B., Field Assistant* Section of Applied Botany and Plant Pathology J. Cedric Carter. Ph.D., J'lanl Pathohigisl and Head J. L. Forsberc, Ph.D., Plant Pathologist G. H. BoEWE, M.S., Associate Plant Pathologist Robert A. Evers, Ph.D., Associate Botanist Robert Dan Neely, Ph.D., Associate Plant Pathologist E. B, HiMEi.icK, Ph.D., Associate Plant Pathologist Walter Hartstirn, Ph.D., Assistant Plant Pathologist D. F. Schoeneweiss, Ph.D., Assistant Plant Palhologi Herley C. Thompson, B.S., Research Assistant Section of Wildlife Research Thomas G. Scoit, fti.U., Game Specialist and Head Ralph E. Veatter, Ph.D., Game Specialist Carl O. Mohr, Ph.D., Game Specialist V. C. Bellrose, B.S., Game Specialiit H. C. Hanson, Ph.D., Associate Game Specialist Richard R. Grader, Ph.D., Associate Wildlife Specialist Ronald F. Labisky, M.S., Assistant Wildlife Specialist Marjorie J. Schlatter. Technical Assistant Howard Crum, Jr., Field Assistant John L. Roseberry, B.S., Technical Assistant Rexford D. Lord, D.Sc, Project Leader* Frederick Greeley, Ph.D., Project Leader* Glen C. Sanderson, M.A., Project Leader* Robert I. Smith, M,S.. Project Leader* Jack A. Ellis, M.S., Assistant Project Leader* William L. Anderson, B.S., Assistant Project Leader* Thomas R. B. Barr, M.V.Sc, M.R.C.V.S. Research Assistant* Bobbie Ioe Verts, M.S., Field Mammalogist* F.rwin W. Pearson. M.S.. Field Mammalogist* Richard D. Andrews, M.S., Field Mammalogist* Keith P. Dauphin, Assistant Laboratory Attendant' Section of Publications and Public Relations James S. Ayars, B.S., Technical Editor and Head Blanche P. Young, B.A., Assistant Technical Editor William E. Clark. Assistant Technical Photographer Marguerite Verlev, B.A., Technical Assistant \ Technical Library Ruth R. Warrick, Nf.ll Miles, M.S., Librarian B.S., B.S.L.S., Technical Librarian B.S.L.S., Assistant Technical CONSULTANTS: Herpetology, Hobart M. Smith, Ph.D.. Professor of Zoology, University of Ulinois ; Parasitology, Norman D. Lkvink. Ph.D.. Professor of Veterinary Parasitology and of Veterinary Research. University oi Illinois: Wildlife Research, Wulnrd D. Klimstra, Ph.D., Professor of Zoology and Director of Co-operative Wildlife Research, Southern Illinois University. i •Employed on co-operative projects with one of several agencies: University of Illinois, Illinois Agricultural Extension Service, Illinois Department of Conservation. United States Army Surgeon General's Office, United States Department of Agriculture. I'nited States Fish and Wildlife Service, United States Public Health Service, and others. This paper is a contribution from the Section of Aquatic Biology. (16068—6M—5-60) CONTENTS Acknowledgments 345 Experimental Ponds and Their Watersheds 346 Experimental Procedures 353 Stocking the Ponds 353 Fertilizing the Ponds 354 Collecting Fishing Data 355 Censusing the Fish Populations 356 Pond Fertilization and Plant Life 356 Pond Fertilization and Fishing Success 358 Sizes of Fish Caught 361 Annual Hook-and-Line Yields 363 Catch Rates 365 Catch Rates for Fish That Were Harvested 367 Trends in Catch Rates 373 Fishing Pressures and Catch Rates 375 Fertilization Rates and Catch Rates 375 Pond Fertilization and Standing Crops 376 Standing Crops and Fishing Success 380 Field Fertilization and Fishing Success 383 Economics of Pond Fertilization 385 Anglers' Evaluation of Ponds 386 Summary 387 Literature Cited 389 % / .-#(£* ».^5»*jv ,v . •^, i Hook-and-Line Catch in Fertilized and Unfertilized Ponds DONALD F.HANSEN GEORGE W.BENNETT ROBERT J.WEBB* JOHN M. LEWIS* EXPERIMENTS carried on in the United States during the past 30 years have shown that the total weight of fish in a pond, that is, the stand- ing crop, may be increased two to six times through the use of fertilizers (Davis & Wiebe 1931; Smith & Swingle 1939; Smith & Moyle 1945; Surber 1945, \94Sb; Swingle 1947; Ball 1949; Ball & Tait 1952). These experiments have quite naturally led to the speculation that fertilization is a means of improving hook-and-line fish- ing. While the practice of fertilizing ponds has been widely recommended to pond owners, few attempts have been made to measure the effect of fertilization on angling results. In published studies of angling in ponds (King 1943; Swingle 1945; Smith 1952, 1954) results have been inconclusive with respect to the effect of fertilization on catch of fish per hour. Studies of the effects of fertilization on aquatic plant life, on animals eaten by fish, and on fish crops have been reviewed bv Neess (1949), Maciolek (1954), and Mortimer & Hickling (1954). The objective of the pond fertilization experiment reported in this paper was to measure the effect of certain fertilization practices on sport fishing for largemouth bass, Micropterus salmoides (Lacepede), and bluegills, Lepomis macrochirus Rafin- esque, in small ponds located in a region of relativelv unproductive soils. From catch records gathered over a 6-year pe- riod, 1947-1952, from three fertilized ponds and three unfertilized or control ponds, we have been able to compare the sizes of the fish caught, the annual hook- and-line yields, and the catch rates in terms of fish per fisherman-hour. The six ponds used in the experiment are lo- *Rnbert J. Webb is Superintendent and John M. Lewis is Assistant Superintendent of the University of Illinois College of Agriculture Dixon Springs Experiment Station. cated at the University of Illinois College of Agriculture Dixon Springs Experi- ment Station in Pope County, southern Illinois. The methods of stocking and fertilizing were, in part, variations of those first pro- posed by Swingle & Smith (1941:224-5, 1942:12-3, 16-8). Recommendations of Swingle Si Smith for minimum fertiliza- tion were followed closely during the last 2 years of the 6-year study. A census of the fish population of each of the ponds was made in the fall of 1953. In the census operations all fish in the ponds were killed with rotenone so that we were able to compare standing crops of fishes in the ponds that had been treated with fertilizer for an extended period (7 years) with the standing crops in the ponds that had not been treated with fertilizer. In addition, we were able to compare the standing crop of fishes in each pond with the hook-and-line fish yields and catch rates recorded during the last 3 years of angling. Published data on angling success in ponds stocked with only largemouth bass and bluegills are scarce. The present study demonstrates the value of this pop- ular combination of fishes, as well as the effect of fertilization, in southern Illinois ponds. ACKNOWLEDGMENTS Information on soils and soil treatments at the Dixon Springs Experiment Station was furnished by C. A. Van Doren of the United States Soil Conservation Serv- ice and by the following persons from the University of Illinois College of Agricul- ture: W. G. Kammlade, Leah M. Dunn, George E. McKibben. and Leland E. Gard. The following persons, all with the College of Agriculture, were con- sulted on general questions pertaining to soils and soil fertilitv : A. L. Lang, [ 345 ] 346 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 Lawrence H. Miller, Roger H. Bray, Russell '1". Odcll, Herman L. Wascher, J. B. P>hrenbacher, and the late Robert F. Fuellenian. H. \V. Norton, Professor of Agricultural Statistical Design and Analysis. Animal Science Department, has examined the data and has verified certain conclusions reached in this study. Water samples from the experimental ponds were analyzed by T. E. Larson of the Illinois Water Survey. Fishing boats were provided by the Illinois Department of Conservation through the courtesy of Sam A. Parr, formerly Superintendent of the Division of Fisheries, now Admin- istrative Assistant. Help wath fertilizing the ponds or with the rotenone census was given by R. Weldon Larimore, William N. Nuess, Robert Crompton, and the late Dan Avery, employed by the Illinois Nat- ural History Survey, and by Ray Brown, Guy Bellamy, Leonard Durham, and Oliver Dick, employed by the Department of Conservation. Charles Stubbs in 1947, Maurice G. Kellogg in 1948, 1949, and 1950, Stacy Gebhards in 1951, and Charles R. Peters in 1952 served as test anglers. The pho- tograph for the frontispiece and the aerial photographs were made by Charles Scott, formerly employed by the Illinois Natural History Survey and now picture editor of the Milwaukee Journal. The other pho- tograph was taken by George W. Ben- nett. The manuscript was read by Wil- liam C. Starrett and edited by James S. Ayars and Mrs. Diana R. Braverman, all of the Illinois Natural History Survey staff. EXPERIMENTAL PONDS AND THEIR WATERSHEDS The ponds selected for use in this ex- periment—Lauderdale, Hooker, Phelps, Wells, Boaz, and Elam, figs. 1-6—are stock-watering ponds built at the Dixon Springs Experiment Station in the period 1935-1940. All have earthen dams. All are fenced and, during the years of the experiment, cattle seldom had access to them. They are all within a 2-mile radius of the Experiment Station headquarters. In September, 1951, at a time when these ponds were full of water, thev ranged in surface area from 0.92 to 1.55 acres, and from 8.5 to 15.0 feet in maxi- mum depth, table 1. Since the only source of water for the ponds was surface run- off, there was always a reduction in water area and in depth during dry weather of late summer. Presumably these water level reductions varied in the six ponds in accordance with relative size of drainage areas, number of domestic animals using the water, shape of the pond basins, and rates of runoff, evaporation, and under- ground seepage. In the fall of 1953, after one of the driest summers on record, the reduction in surface area of the various ponds ranged from 13 per cent in one pond to 49 per cent in another, table 1. There was little difference between the late summer levels of 1953 and those of 1952, another dry year. We have esti- mated from general observations that late summer water levels in 1952 and 1953 w^ere 1 to 2 feet lower than those of most other years represented in this study. Al- though in 1953 Wells Pond showed the greatest reduction in surface area, in most years Phelps Pond showed the greatest reduction. The test anglers made weekly measure- ments of surface water temperatures through the summers of 1947 and 1948. Temperatures above 90 degrees F. were rarely encountered in the series of weekly readings. The maximum surface tempera- ture reading at any of the ponds was 94 degrees, observed at Boaz Pond, first on July 29 and again on August 5, 1947, and NO r-^ On On r~; no' 'vo' r-^ rf -"f * "^ 00 00 oo * * ^ O O O O ro CO ro CN Cn! (N " OO OO OC ' (N C^_ CN CS t^ r-^ r-^ r-^ so "^_ OO CO CO CO cN c^l On r- r-^ r-^ r-4 (N OO r^ r-^ r^ o t! S 4 HE W cs ^ v c < s fe u ., ° £i s ^ H E tJ< Tt< Tt< so OO OO OO r^ r-- r^ C O O O OC OO NO NO CO CO O O ON On OO -^. .— , copq—. ON ON q -H --!; On 0\ On 'r\ OO *' CO O OO On r--' ^. "A ^ * Tf On OO OO 00 ^H ^ C ^ ^ „ OC CO _ CO . . . c^i iJ ;^ 4J 60 bi) bh >^(X— C- 3 3 3 — NO O CO I^ '*' "^ CO C-l — —I ~^ ~ — ' ,- >. >. x^ ^ ^ >• rt rt rt o r\ n rt r^ OC ON o .— tN CO^ Tt* ^ VO VO U^ U-t CK ^ On On ^ On On o ii O £ O S Z £• J2 S , §•§:-& rv u a— ' O i;^ c/:i -t-* I ° •sc-jc; 8 4J V >^ _ij o 3 a .= X-*"N T3 J3 0^ O- •|zss inch bass were hatched in 1946. Green sunfish that later were caught occasionally in two of the ponds, Phelps and Boaz, may have been placed there accidentally with the 1-inch bluegills. The sizes of the fish used were the sizes most readily avail- able from Lake Glendale. Whereas Swingle & Smith (1942:13) suggested the use of fingerling bass and bluegills where both species were to be used in stocking in the fall of the year, we departed from their recommendation by using small adult bass as well as bass fingerlings. Each of the largemouth bass placed in the ponds was marked by removal of a pectoral fin clipped close to the body ; the bluegills were not marked. Fertilizing the Ponds Chemical fertilizers, which contained nitrogen, phosphorus, and potassium (N- P-K), were applied to Lauderdale, Hook- er, and Phelps each year, 1947-1953; no fertilizer was used in Wells, Boaz, or Elam. Numbers of treatments, periods of treatments in different years, and N-P-K formulas are given in table 7. In terms of the number of treatments given and total quantity of nitrogen, phosphorus, and potassium introduced during any single year, fertilization was lighter dur- ing the first 3 years than during the last 4, except that in 1950 the quantity of phosphorus applied to Phelps was slightly less than was applied in any of the previ- ous 3 years. As recommended by Swingle & Smith (1942:16), crushed limestone was used in addition to the nitrogen, phosphorus, and potassium fertilizers when ammonium sulfate was used to supply nitrogen (1947-1949). It was intended that the three ponds to be fertilized should be dosed at the same rates. Dosages ap- plied were computed from areas obtained from the best maps available in 1947. When the ponds were mapped by plane table in 1951, the maps that had been used were found to contain errors. These er- rors account for the different amounts of N-P-K applied to the three ponds in the years previous to 1953, table 7. The methods of treating the three fer- tilized ponds in the Dixon Springs experi- ment were similar to those described bv Swingle & Smith (1942:16-8). These August, 1960 Hansen et al.: Hook-and-Line Catch 355 authors recommended a formula for the amount of fertilizer to be used at each application but allowed for considerable flexibility in the number of applications to be given within a year. The N-P-K formula used in the ponds at Dixon Springs in 1947—1949 was similar to, but was heavier in phosphorus than, the one described by Swingle & Smith. The dos- age rate used at Dixon Springs in 1950- 1953 was a still closer approximation of the Swingle & Smith rate. The Swingle & Smith technique of dosing ponds as often as necessary to maintain blooms of plankton algae was followed only in 1950. Numbers of applications in other years (four per year in the period 1947-1949 and eight per year in the period 1951- 1953) were selected arbitrarily. The Swingle & Smith recommendation that fertilization be delayed in the spring until danger of overflow is past, usually April or May in Alabama, could not easily be followed at Dixon Springs, where rains heavy enough to cause overflow of the ponds often occur as late as June or July. Dosages were based on pond areas at full stage and were not reduced when pond areas shrank in midsummer. No attempt was made to replace fertilizer losses which may have occurred through overflow of water. The chemical compounds used as sources of nitrogen, phosphorus, and potassium were ammonium sulfate (or nitrate), su- perphosphate, and muriate of potash. These compounds were weighed separately as needed, then mixed, and broadcast into the shallow w^ater along the shore of each of the three ponds selected for fertiliza- tion ; most of the fertilizer fell where the water was 2 to 4 feet deep. Distribution of fertilizer was always made around the entire pond. When the ponds were treated only four times a year (1947-1949) the individual treatments were usually spaced 2 to 4 weeks apart. Treatments were postponed if blooms of aleae were so dense as to obscure the Secchi disc at a depth of 24 inches or less. They were postponed in 1947, also, dur- ing the period of decay of aquatic plants (mainlv Chara spp.) that had been killed bv earlier treatments. When the ponds were treated eight times a year (1951- 1953) many of the treatments were given at 1-week intervals, without regard to the density of the blooms, or to the transpar- ency of the water, as measured by the depth at which a Secchi disc was visible. There was no indication that these closely spaced treatments had any adverse effect upon the fish populations; dead fish were not reported in any of the ponds. Collecting Fishing Data Creel data were obtained through con- trolled public fishing and through test fishing by Illinois Natural History Sur- vey employees. Since two of the ponds — Lauderdale and Wells—were fished al- most exclusively by the test anglers and since certain data presented here from all six ponds were gathered entirely by the test anglers, it is appropriate to describe test fishing routines in some detail. At least one test angler fished each pond once a week from early June to early September, or about 12 times a sum- mer. Occasionally one of the test anglers was joined by another fisherman, usually a fellow staff member. The test angler fished one fertilized pond and one control pond on each fishing day ; Lauderdale was paired with Wells, Hooker with Boaz, and Phelps with Elam. Each pond was fished alternately in the morning of one week and the afternoon of the following week. The senior author of this paper, as well as the regular test angler, fished the six ponds throughout the summers of 1948 and 1949. In the other years of the ex- periment the test fishing was done prin- cipally by one man. Ordinarily a test angler fished the ponds for 2 hours on each visit, spending about 1 hour fishing with fly rod and/or casting rod with artificial baits and 1 hour fishing with fly rod and natural baits, usually worms. All captured fish were placed on string- ers until the end of the 2-hour fishing period ; then each fish was measured and weighed. Bass measuring 10.0 inches (total length) or longer and bluegills measuring 6.0 inches (total length) or longer were kept; the others were returned to the Dond. Considerable mortality occurred in hot weather, notably among small fish. The fish caught by the test anglers were measured to the nearest tenth of an 356 Ili.ixois Natural History Survey Bulletin Vol. 27, Art. 5 inch and they were weighed to the nearest 4-gram interval on a John Chatillon & Sons 1 ,000-gram spring scale. The weights were later converted to pounds. Public fishing was allowed in four of the ponds, Hooker, Phelps, Boaz. and Elam, under a special permit system. A grocery in Glendale and the Lake Glen- dale bathhouse were used as permit sta- tions. Fishermen were allowed to fish in Lauderdale and Wells if they accom- panied the test anglers on regularly sched- uled trips; few permit fishermen took advantage of this arrangement. Lauder- dale and AVells were excluded as regular permit ponds in order to be assured of an equal or nearly equal amount of fishing time on one fertilized pond and one con- trol pond. Under the now widely used permit svstem, each fisherman selected the pond where he wished to fish and was issued a 1-day permit for that pond in ex- change for his state fishing license. At the end of his period of angling the fisherman submitted his fish for counting and weigh- ing and recovered his state fishing license. Information recorded for each permit fish- ing period included time spent, types of baits used (plugs, flies, worms), and, for each species of fish, weight of the fish kept and an estimate of the number thrown back. The fish caught by the per- mit fishermen were not measured or weighed individually. One boat was kept on each pond for use by test anglers and permit fishermen. Fishermen supplied their own oars or sculling paddles. The use of minnows for bait was prohibited in order to guard against contamination of the ponds with unwanted species. Earthworms or catalpa worms were by far the most popular baits used by permit fishermen ; plugs were next in popularity. Throughout the experiment, anglers were limited by state law to 10 bass a day; they were also limited to 50 bluegills a day until that limit was removed on July 1, 1951. These creel limits were seldom approached by either the test anglers or the permit fishermen. A 10-inch legal size limit on bass was in force throughout the state until July 1, 1951. People fish- ing on the six Dixon Springs ponds were asked to continue observing the 10-inch limit until termination of the experiment. The ponds were open to fishing each day from 6 A.M. to 9 P.M., May 15 through the first Monday in September. The permit fishermen were not in- formed as to which ponds were treated with fertilizer, nor were they often re- minded that a test of pond fertilization was in progress. Although fishing regulations were posted at each pond there were some violations, including poaching. Gensusing the Fish Populations In order to determine the standing crops of fish (numbers and weights) in the Dixon Springs ponds, we killed the fish with rotenone and censused the popu- lations in the period September 8-17, 1953. Cube powder (5 per cent rotenone con- tent) was applied to the ponds at the rate of 3 pounds of powder per acre-foot of water. Fish were collected, counted, and weighed on the day the rotenone was in- troduced and on each of the succeeding three days. Because insignificant numbers of fish were found on the fourth day after treatment, no counts were made on that day or later. POND FERTILIZATION AND PLANT LIFE The use of chemical fertilizers in the Dixon Springs ponds resulted in increased abundance of plankton algae in each of the treated ponds and in periodic heavy growths of filamentous algae, particularly in one pond. The fertilization program was detrimental to the growth of rooted aquatics. Blooms of plankton algae, similar to those described by Swingle Si. Smith (1942), appeared in the fertilized pond^; each year. The blooms occurred after two to four applications of fertilizer. The number of treatments required to produce these blooms varied with the pond and the year. Blooms were much heavier in some years than others. They were light at Lauderdale, for example, in 1950 and 1951. The effect of blooms on water transparency may be seen in table 8. Light blooms were sometimes observed in the control ponds but these blooms seldom lasted for more than 1 week at a time. August, 1960 Hansen et al.: Hook-and-Line Catch 357 Once the blooms were established in the fertilized ponds they lasted as long as 2 to 8 weeks without further additions of ferti- lizer. When a bloom began to disappear, an additional application of fertilizer usuall}' resulted in an increase in its den- sity within 1 or 2 days. Ball & Tanner (1951:9) found that in North Twin Lake, Michigan, an increase in plankton followed each application of fertilizer. In the Dixon Springs ponds, surface growths of filamentous algae—probably stimulated by the pond treatments—were a hindrance to fishing in some years, but perhaps did not seriously affect fish yields or catch rates. Such growths were present in all three fertilized ponds in the summer of 1947, the first year in which fertilizer was used, and were especially heavy at Lauderdale Pond in the summers of 1948, 1950, and 1951. At various times during these 3 years filamentous algae covered 25 to 75 per cent of the surface of Lauder- dale Pond, fig. 7. Anglers sometimes had to clear away algae before fishing their favorite spots. However, Lauderdale pro- duced by far the best fishing in spite of this growth of filamentous algae. Sur- face growths were sometimes observed on the control ponds, but they covered only small areas and were present for only very short periods. The floating algae on Lauderdale was identified as Rhizoclon- ium sp. Heavy growths of filamentous algae in chemically fertilized ponds have been re- Table 8.—Average depths (in inches) at which a Secchi disc was visible below the surface of each of the six Dixon Springs ponds (weekly observations averaged by months), monthly averages for fertilized and for unfertilized ponds, and differences between monthly averages. The lower transparency of the fertilized ponds generally resulted from blooms of plankton algae. Year and Month 1947 lune* . . July... August . 1948 June . . July... August . 1949 June . . July... August. 1950 Tune . . July... August. 1951 June . . July... August 1952 June . . July... August Fertilized Lauderdale 56 51 15 17 17 20 30 14 22 39 34 58t 14 35 43 12 14 11 Hooker 33 17 26 21 16 21 20 19 13 12 15 39 33 27 13 12 19 Phelps 51 15 25 22 18 23 19 12 16 11 12 14 20 13 Aver- age 56 45 16 23 20 18 25 18 18 22 19 28 29 28 11 13 13 Unfertilized WelL- 36 41 36 31 37 25 37 39 39 28 29 30 26 50 20 31 14 16 Boaz 11 6t 16 20 21 33 35 35 28 39 36 23 35 48 44 40 39 Elam 62 63 30 31 29 30 33 36 33 36 38 38 42 56 39 22 20 Aver- age 36 38 35 26 29 25 33 36 37 30 35 35 42 41 38 25 25 Difference Between Averages Fertilized Clearer Unfertilized Clearer 19 3 9 7 18 19 16 7 7 13 13 27 12 12 Readings were begun late in the month. A single reading at Hooker <^ as recorded as very clear.' A single reading at Elam was recorded as 38 inches; no readings were made at Phelps or Boaz during June. tThe low readings at Boaz in 1947 were the result of nearly continuous muddiness, for which no cause could be found. , , , JThe reading was 108 inches at Lauderdale Pond on August 27, 1950. This was the highejt reading made at any lime in any of the six ponds. 358 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 Fig. 7.—Lauderdale Pond, August, 1950, with surface partially covered with a growth of filamentous algae, after the pond had been fertilized. ported by Patriarche k Ball (1949:29) in southern Michigan, by Surber (1945: 388) in West Virginia, by Zeller (1953: 286) in Missouri, and by Smith & Swingle (1942) in Alabama. Bottom-inhabiting filamentous algae (unidentified) were sometimes present in both fertilized and unfertilized ponds at Dixon Springs, but usually for only brief periods. However, such algae were found to be a nuisance to fishermen at Lauder- dale throughout the summer of 1952. Dense stands of Chara in the three fer- tilized ponds died in 1947, after three fertilizer applications; for as long as fer- tilizer was used (from the spring of 1947 through the summer of 1953) this plant remained extremely scarce. Chara nearly covered the bottoms of the three control ponds throughout the study. An increase in abundance of Chara was seen in Lauder- dale, Hooker, and Phelps during 1954 and 1955, the first years after 1947 in which no fertilizer was used ; however, in 1956 Chara had still not regained its prefertilization abundance. The disappearance of submerged weeds in ponds treated with chemical fertilizers was observed by Swingle & Smith (1942). These authors recommended winter fer- tilization to destroy undesirable sub- merged aquatic plants and periodic fer- tilization to prevent their re-establishment. Surber (1948^) reported that a variety of rooted aquatic plants had been killed after use of a chemical fertilizer at Deer Lake, New Jersey. Ball & Tanner (1951:11) found that chemical fertilizer all but destroyed Chara and Potamogeton in North Twin Lake, Michigan, but that each returned to its former abundance the year following termination of fertilization of the lake. POND FERTILIZATION AND FISHING SUCCESS The pond fertilization program at Dixon Springs can be evaluated by com- paring the three fertilized ponds, Lauder- dale, Hooker, and Phelps, with the three control or unfertilized ponds. Wells, August-, 1960 Hansen et al.: Hook-and-Line Catch 359 Table 9.—Numbers of largemouth bass, in various length classes, caught by Illinois Nat- ural History Survey test anglers in three fertilized ponds at Dixon Springs. Bass of less than 10 inches in length were returned to the water. Numerals in boldface type represent bass (marked by fin removal) used in stocking the ponds. Lauderdale 1947 1948 1949 1950 1951 1952 Hooker 1947 1948 1949 1950 1951 1952 Phelps 1947 1948 1949 1950 1951 1952 1 5 10 15 5 2C 5 3 2 3 2 2 4 2 2 1 2 5 1 3 2 1 1 1 1 69 23 34 57 39 1 1 2 25 60 40 52 17 28 43 14 50 10.8 72 11 11.7 48 16 2>2> 13 11.4 47 11.4 58 11.7 50 30 12.0 77 24 10.6 28 10.9 41 10,4 10.1 10.6 23 46 10.0 14 16 10.2 61 10.3 16 10.8 38 11.7 75 12.0 29 *Each number designating inches represents the mid-point in a length class; for example, the number 4.5 includes the bass of 4.3-4.7 inches total length. 360 Illinois Natural History Survey Buli.i-tin Vol. 27, Art. 5 Table 10.—Numbers of largemouth bass, in various length classes, caught by Illinois Nat- ural History Survey test anglers in three unfertilized ponds at Dixon Springs. Bass of less than 10 inches in length were returned to the water. Numerals in boldface type represent bass (marked by fin removal) used in stocking the ponds. I 1 Length Class, Inches* Wells 1947 1948 1949 1950 1951 1952 BOAZ 1947 1948 1949 1950 1951 1952 Elam 1947 1948 1949 1950 1951 1952 5.0. 5.5. 6.0. 6.5. 7.0. 7.5. 8.0. 8.5. 9.0. 9.5. 10.0. 10.5. 11.0 11.5. 12.0. 12.5. 13.0. 13.5. 14.0. 14.5. 15.0. 15.5. 16.0. 16.5. 17.0. 17.5. 18.0. 18.5. 19.0. 19.5. 20.0. 20.5. Total 2 3 2 1 8 9 15 7 8 7 3 1 15 50 44 19 12 30 34 16 13 43 71 50 36 21 Number in 10- inch class or larger . . Average length of fish, 10-inch cla.<(s or larger . . Per cent in 10- inch class or larger . . 15 11 15 12 16 17 12 20 12 11.1 100 12.4 22 11.2 34 11.2 60 11.7 84 12.1 77 10.6 13.0 10.3 11.0 11.2 11.3 11.0 11.5 11.9 10.6 10.7 11.81 89 33 7 35 44 69 100 12 13 36 56 57 •Each number designatinK inches represents the bass of 4.8-5.2 inches total length. the mid-point in a length class; for example, the number 5.0 includes August, 1960 Hansen et al.: Hook-and-Line Catch 361 Boaz, and Elam, with respect to the sizes of fish caught, the annual fish yields, and the catches per fisherman-hour. Sizes of Fish Caught Length distributions of all bass and all bluegills caught by the test anglers are shown for the six ponds in tables 9, 10, 12, and 13; these tabulations include the bass under 10 inches and the bluegills un- der 6 inches that were put back in the ponds after measurement. The average weights of fish caught and kept by test anglers and permit fishermen are shown in tables 11 and 14; lengths of fish caught by permit fishermen were not recorded. Few of the bass caught by test anglers measured more than 13 inches; the only Table 11.—Average weights (in pounds) of individual largemouth bass harvested by hook and line from each of the Dixon Springs ponds in each of 6 years. Data from which the figures were derived are in table 20. Pond 362 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 ones over lb inches were caught in a fertilized pond, Lauderdale. The bass of 10 inches or longer taken by the test anglers from fertilized ponds, table 9, were smaller on an average than those from the control ponds, table 10; those from the three fertilized ponds averaged 11.5, 10.5, and 10.8 inches; those from the three control ponds averaged 11.6, 11.2, and 11.3 inches. The individual bass harvested by test anglers and permit fishermen from the control ponds had a higher average weight than those from the fertilized ponds, table 11. The number of captures of marked bass, those with which the ponds had been stocked in 1946, are indicated in tables 9 and 10. Few marked bass were caught after the second season of fishing. The marked bass grew faster in some ponds Table 13.—Numbers of bluegills. in various length classes, caught by Illinois Natural His- tor>' Survey test anglers in three unfertilized ponds at Dixon Springs. Bluegills of less than 6 inches in length were returned to the water. Length Class, Inches* August, 1960 Hansen et ah: Hook-and-Line Catch 363 than in others. The rate of stocking of the fertilized ponds, which was three times that of the control ponds, may have re- sulted in at least a temporary state of over- crowding and a consequent retardation in growth of the bass placed in two of the fertilized ponds, Phelps and Hooker. Size distributions of bass caught by test fisher- men in 1947 and 1948 indicated no over- crowding in Lauderdale or in any of the controls. While the size distributions of bluegills caught from fertilized and control ponds were similar, the fertilized ponds yielded bluegills of larger average size, and more bluegills of extra large size (8-8^/2 inches), than the control ponds, tables 12 and 13. The individual bluegills kept by the test anglers and permit fishermen, 1948-1952, averaged at least one-fourth pound every year at Phelps and in 4 out of 5 years at Lauderdale and Hooker, table 14. In each of the control ponds. Wells, Boaz, and Elam, the individual bluegills averaged one-fourth pound or heavier in only 1 out of 5 years. For all years combined, bluegills harvested from the fertilized ponds averaged 0.27 pound per fish, those from the controls 0.22 pound. The three largest bluegill specimens caught by the test anglers came from the fertilized ponds ; their lengths and weights were 8.6 inches and 0.51 pound, 8.7 inches and 0.53 pound, 8.7 inches and 0.55 pound. However, these were not the largest bluegills caught in the fertilized ponds. On June 3, 1951, a permit fisher- man on Phelps Pond caught 12 bluegills that averaged 0.63 pound per fish. Annual Hook-and-Line Yields The recorded hook-and-line yields from the ponds in this experiment are probably not the maximum yields of which the ponds were capable. More fishing might have been done, and more fish might have been removed, if the ponds had been open to year-round fishing, and if there had not been many other places to fish in the neighborhood—other farm ponds. Lake Glendale, and large and small streams. Some fishermen may have avoided the ex- perimental ponds because they preferred fishing where permission to fish and re- porting of catches were not required. The true hook-and-line yields were somewhat higher than the recorded yields because the records did not include the fish taken by poachers. Fishing effort in man-hours per acre and yield in terms of the number and weight of bass and bluegills harvested per acre are given in table 15. The actual recorded numbers and weights of fish re- moved from the ponds, data from which per-acre yields were computed, are shown in table 20. Yields of bluegills from most ponds increased somewhat between the early and late years of the experiment. During 1947, in the first summer of fish- ing, the yield of bass measuring 10 inches or larger was much greater from Lauder- dale Pond than from Hooker or Phelps or from any of the control ponds, table 15. This high 1947 yield, 51 fish per acre (47 fish), was not equaled in later years at Lauderdale or at any of the other ponds during the period of the study reported here. The annual hook-and-line yield of bass and bluegills combined averaged 48 pounds per acre from the fertilized ponds and 25 pounds per acre from the control ponds, table 16. The highest recorded 1- year yield from a fertilized pond (Lauder- dale) was 88 pounds per acre, from a control pond (Boaz) 42 pounds per acre, table 15. Presumably, higher yields from the fertilized ponds can be attributed for the most part to the better bluegill fish- ing. It should be noticed that the fer- tilized ponds were fished more intensively than the controls. In fertilized and con- trol ponds where total hours of fishing were about the same for the whole experi- ment (Lauderdale and Wells, Phelps and Boaz), the bluegill yields of fertilized ponds exceeded the bluegill yields of the controls in both numbers and pounds per acre, table 16. For the control ponds in the 5 years in which both species were caught, the total bass yield in pounds (actual, not per acre) almost equaled the total yield of bluegills, table 17; the bass yield exceeded the bluegill yield in two of the control ponds. In the fertilized ponds the total bluegill yield in pounds was three times the bass yield. Published data showing the effect of pond fertilization on hook-and-line yields 364 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 are scarce; no such data have been found for ponds stocked with bass and bluegills alone. Dugan (1^51:415) published an- nual yields of a number of fertilized ponds in West Virginia, some of which con- tained a bass-bluegill combination, but he did not have yield data from unfertilized ponds containing this combination. In two of the West Virginia ponds, yields of bass and bluegills were higher than the yields in the fertilized ponds at the Dixon Springs Experiment Station, but the West Virginia ponds were fished more inten- sivelv. In Alabama, Swingle (1945:305) showed a large difference in annual hook- and-line yields between a fertilized pond and an unfertilized pond, each containing Table 15.—Man-hours of fishing per acre and number and weight of fish per acre removed by hook and line from each Dixon Springs pond during the years 1947-1952. Catch data from which figures were derived are in table 20. Years in which fertilizers were applied to pond watersheds are indicated by S (for spring preceding the fishing season) and F (for fall near the end of the fishing season). Additional data on watershed fertilization are shown in table 5. August, 1960 Hansen et al.: Hook-and-Line Catch 365 Table 16.—Average annual number of man-hours of fishing per acre and average annual hook-and-line yield of largemouth bass and bluegills per acre for the 5-year period 1948-1952 at the six Dixon Springs ponds. Data for individual years are shown in table 15. 366 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 0* ^ c ^•5 OS August, 1960 Hansen et al. : Hook-and-Line Catch 367 caught by the test anglers ; these fish included some too small to keep. The efforts of fish managers often are directed toward increasing the numbers of large fish in a population by reducing the abundance of small fish, that is, by thin- ning stunted populations. These efforts may not be appreciated by a group of fishermen who are less concerned with the size of fish than with the number of fish they catch. This group includes many children and some adults. The rates at which the test anglers at the Dixon Springs ponds caught bass and bluegills above certain minimum lengths are shown in tables 18 and 19. The catch rates for bass less than 10 inches long and bluegills less than 6 inches long are not harvest rates, since these fish were re- turned to the ponds after they were meas- ured ; some of these fish may have been caught more than once. The fisherman who prizes any fish, no matter how small, would have found the fertilized ponds slightly better than the control ponds for bass fishing but the con- trol ponds slightly better than the fer- tilized ponds for bluegill fishing. The control ponds proved better than the fer- tilized ponds for the capture of bluegills measuring 5 inches or larger. The fisher- man interested in keeping only the fish of moderate to large sizes, for example, bass over 12 inches and bluegills over 7 inches, might have found the control ponds a little more satisfactory for bass fishing and the fertilized ponds a little more satisfactory for bluegill fishing. The bass fisherman interested in keeping only extra large fish would have found all of the ponds disappointing. Catch Rates for Fish That Were Harvested.—We turn now to a consider- ation of catch rates based on fish that were actually harvested. The hook-and-line catch rates for fish harvested from the six ponds at Dixon Springs are given in table 20. It is evi- dent from this table that Lauderdale pro- duced better fishing each year (bass rates added to bluegill rates) in terms of both number and pounds per man-hour than any of the other ponds. It was the only fertilized pond that consistently produced better catch rates (bass and bluegill com- bined) than any of the control ponds. Lauderdale produced better bass fish- ing, in terms of number of fish per man- hour, than any of the controls in 5 out of 6 years and, in terms of pounds per man- hour, than any of the controls in 3 out of 6 years, figs. 8 and 9. In 4 out of 6 years the other fertilized ponds produced poorer bass fishing than any of the control ponds. However, as mentioned earlier, bass fish- ing in Phelps Pond may have been poorer than it should have been in the first year of fishing as a result of relatively heavy stocking. In each year but 1949 Lauderdale led all other ponds in bluegill fishing, figs. 10 and 1 1 ; in that year Phelps led in both number and pounds of bluegills per man- hour. In several different years some of the control ponds had bluegill catch rates that were equal to or better than the catch rates in Hooker or Phelps. The catch rates averaged for six sea- sons of bass fishing and five of bluegill fishing are shown for each pond at the bottom of table 20. Lauderdale ranked well above any of the other ponds in catch rates (bass rates added to bluegill rates). Hooker and Phelps ranked below Wells and Elam and about on a par with Boaz. The three fertilized ponds ranked 1, 5, and 6 in terms of both number and weight of bass kept per hour; 1, 3, and 4 in terms of number of bluegills kept per hour; and 1, 2, and 3 in terms of weight of bluegills kept per hour. In terms of the weight of bluegills kept per hour, two of the fertilized ponds, Phelps and Hooker, outranked the controls by very small margins. However, the fact that all three fertilized ponds outranked the three con- trols is a strong indication that fertiliza- tion was a benefit to bluegill fishing, though the benefit may have been small. At Broadacres Lake, North Carolina, King (1943:209) found that the catch rate was a little lower the year fertilizer was used than the year before. At Crecy Lake in New Brunswick, Smith (1954:2) observed a better catch rate of brook trout after the lake had been fertilized, but this better catch rate may have been due in part to other management efforts car- ried on at the same time, for example, the addition of young trout. There is a statistical possibility that the fertilized ponds, Lauderdale, Hooker, 368 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 •~ i) I- a E 2 >.t Q. O XU tB .Si 3 " ^ -S «2 O w •on « (« "« "^^^ .sis j= a « en C «-o •« ^ C -S O CS ^ u «. ° 3 u ce O V V c C i- « 3 e E = § V c c a ^ w ^« ^3 c 2 O 2 I > 4> O A ^ a»U 0) CC CQ Oh E tr ij c E S- -a w t- o b^ "^ I a,* E S- Z O. ^^I c o oooo oooc> oooc oooc> -hOO>~< 000<2> — O—"-( OOOC; OOOC) —'00 000=:^ vC O oc CC W-1 Tj-— Ol -H W-, oi On ^j CNOO*-! — OOCs ^ — ri >-. •^ ON O <^, C~l O O "-, o o -^ --^ 00 ON *n oo — -^ r4 — (z d> <:i ro sC ^ =C' Tf o o -. d d d <^' j^ oo r^ tv d d d c OOOC; OOOCs CN oo r-1O CN ro ro oo >^ ro Ol CO ro O "^ ro — lo Q (U d u o a So o: Co fa J I Oh ''^ D > PQ M E 2 c:; u. J X 0, "^ ::3 ^ I fa. _: ± 0- ^ D :^ a it; •^ 2 " S u u ?; = § a.^tD 370 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 and Phelps, would have ranked better as Illinois Animal Science Department, tells bluegill fishinfi ponds than the controls us that where relative productivity of even if no fertilizer had been used. H. W. ponds is unknown the random selection Norton, statistician in the University of of the three most productive ponds as the i 1.2 I .0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.0 LARGEMOUTH BASS 1947 1948 1949 1950 1951 1952 Fig. 8.—xNumber of largemouth bass kept per man-hour of angling in fertilized (F) and 'jnfertiiized ponds; data from table 20. August, 1960 Hansen et al.: Hook-and-Line Catch 371 0.7 0.6 0.5 a: g 0.4 0.3 o Q- 0.2 0.1 0.0 - LARGEMOUTH BASS -4-F 1947 1948 1949 1950 1951 Fig. 9.—Weight of largemouth bass kept per man-hour of angling in fertilized (F) unfertilized ponds; data from table 20. 1952 and ones to receive treatment could occur once in 20 times. Although the ponds were chosen for fertilization on an arbitrary rather than on a purely random basis, we had no advance knowledge of how the six ponds might rank as fish-producing waters. The wide variation in catch rates for the three fertilized ponds at Dixon Springs points to the need for studies of catch rates on ponds before, as well as after, fertilization. A study of this kind is now in progress. Wells, Boaz, and Elam, the three control ponds of the study reported here, were restocked in 1954 and fertilized for two seasons. Bluegill catch rates in each of these ponds were better after fer- tilization than before. The fact that bass fishing in both Hooker and Phelps for the period 1947- 1952 was inferior to bass fishing in each of the control ponds, table 20, suggests several possible conclusions: (1) fertili- zation was of no help to bass fishing, (2) the benefits of fertilization varied greatly from pond to pond, or (3) no positive correlation existed between the fish population of a pond and the catch rate. The rotenone census of the fish populations showed that poor bass fishing in Hooker and Phelps may not have been due to scarcity of usable-sized fish in these ponds so much as to the difficulty of catch- ing them. That fishing for both bass and bluegills was generally much better in Lauderdale than in the other fertilized ponds is not easily explained, unless possibly by the lighter fishing pressure, as discussed in the section "Fishing Pressures and Catch Rates." At the time of the 1953 rotenone census, the number per acre of usable- sized bass was smaller in Lauderdale than in Phelps; the number per acre of usable- 372 Ii.i.iNois Natural History Survey Bulletin Vol. 27, Art. 5 4.0 3.0 2.0 0.0 BLUE GILL LAUDERDALE (F)- HOOKER (F) A PHELPS (F) WELLS •• BOAZ — ELAM X 1947 1948 1949 1950 1951 1952 Fig. 10.—Number of bluegills kept per man-hour of angling in fertilized (F) and unfer- tilized ponds; data from table 20. sized bluejj;ills was smaller in Lauderdale than in Phelps or Hooker, table 24. I'hree factors may have been favorable to the growth of fish in Lauderdale for 1 or 2 years at the beginning of the study but not during the last 4 years. ( 1 ) Be- fore the stocking of the ponds for the ex- periment reported here, fish-food organ- isms—invertebrates as well as larval am- phibians—had a longer time to build up their populations in Lauderdale than in Hooker or Phelps. In 1946 Lauderdale was without fish for 6 months prior to stocking (May to November), Hooker and Phelps for onlv 2 months (September to November). Brown & Ball (1943: 267) showed that certain fish-food organ- isms as well as fish were destroyed by the rotenone treatment of Third Sister Lake, Michigan. Ball Si Hayne (1952: 44—5) showed evidence of an expansion in fish-food organisms in a lake after all fish had been removed. (2) In November, 1946, Lauderdale was given a slightly heavier stocking in terms of fish per acre than the other ponds ; this heavier stock- ing might account for the better bass fishing in 1947. Presumably the initial advantage in numbers would have ceased to be a factor in 1948 or 1949, when the offsprinir of the fish used in stocking the pond reached harvestable size. (3) Lauder- dale had been dosed with fertilizer in 1945. As a result of an error in the reported area of the pond, Lauderdale received more fertilizer in terms of pounds per acre at full stage than either Hooker or Phelps. However, water levels in mid- summer were always much lower in Phelps than in Lauderdale, so that Phelps August, 1960 Hansen et al.: Hook-and-Line Catch 373 was probably dosed at least as heavily as Lauderdale after about the middle of July each year. We have shown in table 8 that Lauder- dale was often clearer than Hooker and Phelps, a condition that might have as- sisted fish both in finding food and in locating baits. On the other hand, it is possible that the clearer water increased the chances that the fish might be fright- ened by fishermen. Trends in Catch Rates.—Certain trends in the yearly catch rates were ob- served for both fertilized and unfertilized ponds at Dixon Springs, but trends dif- fered from one pond to another. In some I.I 1.0 0.9 0.8 0.7 - o 0.6 h 0.5 - o D- 0.4 I- 0.3 - 0.2 - 0.1 - 0.0 - BLUEGILL LAUDERDALE (F) 1947 1948 1949 1950 1951 1952 Fig. 11.—Weight of bluegills kept per man-hour of angling in fertilized (F) and unfer- tilized ponds; data from table 20. 374 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 e o .2© • o Si vQ s E'5 u.£ S J= o «> ^ i; 4) (A •0* > •S2 " s e o c ^ 7 N 4) August, 1960 Hansen et al.: Hook-and-Line Catch 375 ponds, bass catch rates changed only slightly during the experiment ; in others, catch rates were high at the beginning, dropped off for 1 or 2 years, and then improved toward the end of the experi- ment. The notion of many fishermen in Pope and Johnson counties that bass fish- ing in small ponds is best the first year they are fished was borne out in the fish- ing results only at Lauderdale and Wells, figs. 8 and 9. The observed depression in bass catch rates seen in some of the ponds in the second or third year after being stocked probably was due to a reduction in the numbers of the original stock of bass as a result of angling and natural mortality, combined with a delay in population re- placement through reproduction. In all of the ponds except Phelps and Lauderdale, figs. 10 and 11, bluegill catch rates were highest during the fourth year of bluegill fishing (the fifth year after stocking). Phelps Pond furnished its best bluegill fishing in the second year and Lauderdale in the fifth year of bluegill fishing. The most common trend in bluegill catch rates—one that was ex- hibited by four of the six ponds—was a general improvement in rates over the first 4 years of bluegill fishing, 1948-1951. Three of these four ponds showed con- spicuous declines in catch rates in the fifth year, 1952. Fishing Pressures and Catch Rates.—Benntn & Weiss (1959) re- cently showed that ponds in Illinois sub- jected to comparatively light fishing pres- sures—Ridge Lake, Big Pond, and the ponds in the present experiment—pro- vided better catch rates than ponds in the Busch Wildlife Area, Missouri, that were subjected to extremely heavy fishing pres- sures. Although we were unable to discover a clearcut relationship between fishing pressures and catch rates in the Dixon Springs ponds, we found that the two ponds with the smallest total number of man-hours of fishing, Lauderdale (fer- tilized) and Wells (unfertilized), had the highest catch rates of bass of desirable sizes, table 20. We have tried in the following discus- sion to eliminate fishing pressure as a possible factor in catch rate calculations by comparing only those ponds that were fished at approximatelv equal rates, table 21. Under equal or nearly equal fishing pressures, bass fishing was in some in- stances better in the fertilized ponds, in other instances better in the controls, but bluegill fishing was consistently better in the fertilized ponds. The catch rates shown for Lauderdale (fertilized) and Wells (control) are of special interest because fishing in these two ponds was done almost entirely by the Natural History Survey test anglers, assuring that not only the number of hours but fishing skills and fishing meth- ods were nearly the same in a given year. In the 4 years that Lauderdale and Wells are represented in table 21, bluegill fishing in terms of number of fish caught per hour was 1.9 to 5.2 times as good in Lauderdale as in Wells—in terms of pounds caught per hour, 2.3 to 4.9 times as good in Lauderdale as in Wells. In the same 4 years, bass fishing was notably bet- ter in Lauderdale than in Wells in 1 year, better in Wells than in Lauderdale in 1 year. Over the entire period of study, total hours of fishing were nearly equal for Lauderdale (fertilized) and Wells (un- fertilized), each fished about 300 hours, and for Phelps (fertilized) and Boaz (unfertilized), each fished in the neigh- borhood of 500 hours, table 20 (bottom). The catch rates for bass, in 6 years of fishing, were better in Lauderdale than in Wells but better in Boaz than in Phelps. The catch rates for bluegills, in 5 years of fishing, were considerably better in Lauderdale than in Wells and somewhat better in Phelps than in Boaz. Fertilization Rates and Catch Rates.—As described in the section "Fer- tilizing the Ponds," the N-P-K formulas used in the period 1947-1949 were dif- ferent from the ones used in later years, table 7. As a consequence of changes in the fertilizer formula and in the number of treatments, the ponds received about 2.0 times as much nitrogen, 1.3 times as much phosphorus (PoO,), and about 3.2 times as much potassium (KoO) in 1951 and in later years as they had received each year in the period 1947-1949. Al- though the number of fertilizer applica- 376 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 Table 22.—Catch rates (number and weight of fish per man-hour of fishing) of largemouth bass and bluegills from Dixon Springs ponds in two periods, one of comparatively light (1947- 1949) and one of comparatively heavy (1951, 1952) fertilization. Details of pond fertilizaticn program are shown in table 7. Figures were derived from data in table 20. Period of FV.rtii.ization Largemouth Bass Number Per Hour Pounds Per Hour Bluegills* Number Per Hour Pounds Per Hour Light (1947-1949) Fertilized ponds. . Unfertilized ponds Difference Heavy (1951,1952) Fertilized ponds . . Unfertilized ponds Difference 0.27 0.23 0.23 0.35 -0.12 0.16 0.17 -0.01 0.16 0.27 -o.n 1.05 0.65 -^0.40 1.88 1.46 -^0.42 0.26 0.13 -\-0.13 0.55 0.32 •Bluegill fishing in 1948, 1949, 1951, and 1952 but not in 1947. tions j^iven annualh' in 1951—1953 was double the number given in 1947-1949, the amount of phosphorus (the compo- nent generally considered to be most im- portant in pond fertilization) was in- creased only about one-third. Catch rates may be compared for the vears under the lighter treatment (1947- '1949 for bass, 1948 and 1949 for bluegills) with the vears under the heavier rates (1951 and 1952), table 22. Bass fishing, as judged by differences in catch rates be- tween fertilized and unfertilized ponds, was relatively better under the lighter treatment ; bluegill fishing—especially in pounds caught per hour—was better un- der the heavier treatment. Since bluegill catch rates improved in the control ponds as well as in the fertilized ponds during the period of the heavier treatments, blue- gill fishing might have improved in the fertilized ponds even if the rate of fertili- zation had not been increased. POND FERTILIZATION AND STANDING CROPS When the standing crops of the Dixon Springs ponds were determined by ro- tenone censuses in September, 1953, the ponds had been closed to all fishing for the 12-month period preceding the census. Fertilization of Lauderdale, Hooker, and Phelps had been continued during the summer of 1953 in approximately the same manner as in 1951 and 1952, table 7. For each pond the standing crop in pounds peH acre was computed from the reduced area" of the pond at the time of the census, rather than from the area at full stage. Both full stage and reduced areas are shown in table 1. Studies bv Brown k Ball (1943), Ball (1948), Carlander & Lewis (1948), and Krumholz (1950a) demonstrated that in some situations considerable percentages of the populations of fish killed by rote- none are not recovered in the census op- erations. A possible hindrance to the re- covery of fish in the control ponds at Dixon Springs was a dense growth of Cham in which dying and dead fish might have become entangled. The possibility that the Chara interfered with the re- covery of fish was not investigated by un- derwater examination. We know of no reason other than the possible effect of Chara to believe that the percentage of fish recovered was different in fertilized than in unfertilized ponds. Bass collected from the ponds after the rotenone treatment were grouped into two length categories— those 10.0 inches (total length) or larger and those smaller than 10.0 inches. The bluegills collected from the first four ponds examined (Lauder- dale, Phelps, Wells, and Boaz) were divided into four length categories as fol- lows: 1.0-1.9, 2.0-3.4, 3.5-5.9, and 6.0 inches or larger. Natural size groupings permitted the rapid sorting of fish into the various length categories, for the most August, 1960 Hansen et al.: Hook-axd-Line Catch 377 part without actual measurement. Blue- ^ills collected from the other two ponds (Hooker and Elam) were grouped into two categories : under 6.0 inches and 6.0 inches or larger. The populations of the first four ponds varied considerably with respect to abund- ance of bluegills in the four length cate- gories, table 23. The variations appear to have been unrelated to the fertilization program. Lauderdale Pond was char- acterized by an absence of bluegills 1.0- 1.9 inches long, by an abundance of blue- gills 2.0-3.4 inches long, and a relative scarcity of bluegills 3.5-5.9 inches long and 6.0 inches or larger. This pond, in which bluegill fishing had been better than in any other, was more remarkable for the weight of 2.0-3.4-inch bluegills (95 pounds per acre) than for the weight of bluegills measuring 6.0 or larger. Two population characteristics were seen in these four ponds, table 23. ( 1 ) While the ponds appeared to be quite densely populated with bluegills under 3.5 inches, they showed no evidence of overpopulation with bluegills of 3.5 inches or longer. (2) In number of bluegills per acre in each of the four ponds, great dif- ferences existed between the two smaller length categories and only minor differ- ences between the two greater length cate- gories. Of the fish that, according to tables 12 and 13, were likely to be caught by anglers (those 3.5 inches or larger), the ones measuring 3.5-5.9 inches were about as numerous as those of greater lengths. The number and weight of bass and bluegills (in two length categories for each species) recovered from each of the six ponds in the rotenone census are shown in table 24. Just as there was overlap in the catch rates for fertilized and unferti- lized ponds, there was also overlap in the standing crops. Bass 10 inches or larger, bluegills 6 inches or larger, and bluegills smaller than 6 inches were a little more abundant in the fertilized ponds, while bass smaller than 10 inches were more abundant in the control ponds, table 24. Eass of all lengths were more abundant in the control ponds, while bluegills of all lengths were more abundant in the fertilized ponds. The weight per acre of bass of all lengths was nearly the same in fertilized as in control ponds; the weight per acre of bluegills of all lengths was higher in the fertilized ponds. The three fertilized ponds averaged 292 pounds of fish per acre (bass and bluegills of all lengths) ; the controls averaged 238 pounds Der acre (ratio 1.2:1). In Alabama ponds treated nine times a season with 6-8-4 fertilizer at the rate of 100 Dounds per acre per treatment and NaNO. at the rate of 10 pounds per acre per treatment—roughly equivalent to the annual treatments applied at Dixon Springs in the period 1951-1953—Swingle (1947:24) found that the average stand- ing crop (weight per acre) of bass and bluegills of all sizes in three fertilized ponds was about double the standing crop in the control pond (ratio 2.0:1). In this Alabama observation, an overlap was Table 23.—Standing crops, in terms of number and weight (per acre), of bluegills recov- ered in the rotenone censuses of four of the six Dixon Springs ponds, September 8-17, 1953; the fish were separated into four length categories. The data from Hooker and Elam ponds are not included in this table because the bluegills from those ponds were separated into only two length groups, under 6 inches and 6 inches and longer. 378 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 •a o .S e CO tl §s •M ^QV N S *•* 4) e « 5 — ££^ Ak U 03 ^•^^ ''Is S ^^ •^ 1. U «-c 2 1 = 2 U 4> IB «•£ « u ** « (" « ^ a S •ae «> -Of •^ OS 4) b O » 5^ B cs as '^ " C u® •- 4) O S.E «> o « S u aj: ^ « « c c ^ a 2 cn « 2 Csl J- -00 3 ^J «1 £ o z: Q. August, 1960 Hansen et al.: Hook-and-Line Catch 379 found between fertilized and control ponds in standing crops of bass but not of blue- gills. In another experiment in which Ala- bama ponds were treated 12 times a sea- son with 6.6-8-2, each time at the rate of 120 pounds per acre, Swingle (1947:22) found that the average of the standing crops of bass and bluegills of all sizes in three fertilized ponds was nearly three times the standing crop in the control pond (ratio 2.9: 1 ). That Alabama ponds showed a better response to fertilization than the Dixon Springs ponds under similar treatment is possibly explained by differences in natural fertility of the Alabama and Illi- nois ponds in question. It might be easier through direct fertilization to double or triple a low standing crop of fish in an area of low soil fertility than in one of somewhat higher soil fertility. The un- treated Alabama ponds, 6 to 12 months after being stocked, contained 100 to 125 pounds of bass and bluegills per acre (Swingle 1947 : 22, 24), whereas the three untreated ponds at Dixon Springs, 6 years after being stocked, contained 169 to 308 pounds of bass and bluegills per acre, table 24. It is possible that in the 6- to 12- month periods between the stocking and draining of the Alabama ponds the stand- ing crops had not had time to reach maxi- mum levels. Krumholz (1948:405, 409) found that ponds stocked in May or June with bluegills alone or with bluegills, largemouth bass, and other species con- tained much larger standing crops the second October than the first October after being stocked. Ball & Tait (1952:6, 17) used some- what less fertilizer in southern Michigan ponds than was used at Dixon Springs in 1951-1953 and obtained a slightly better response from the treatments. Three Michigan ponds were treated five times a season with 10-6-4 fertilizer at the rate of 100 pounds per acre each time. The fertilized ponds had standing crops of bass and bluegills that averaged 365 pounds per acre, and three similar, un- fertilized ponds had standing crops that averaged 261 pounds per acre (ratio 1.4:1). There was a very wide range in the standing crops of the fertilized ponds, 165 to 721 pounds per acre; the standing crops of the unfertilized ponds ranged from 209 to 379 pounds per acre. In West Virginia, Surber (1948/*) studied the effect of various rates of ap- plication of 10-5-5 fertilizer on the blue- gill production in hatchery ponds. Three groups of ponds were treated five to seven times a growing season at rates of 100, 200, or 300 pounds of 10-5-5 fertilizer per treatment. Combining the data of Surber (1948Z': 201-2) for summer and fall hatchery crops (but omitting the data from a pond in which there was abnor- mally high mortality) we find that crop weights were 1.9, 2.3, and 2.3 times as large in the three groups of fertilized ponds as in the control ponds. STANDING CROPS AND FISHING SUCCESS For many years aquatic biologists have been interested in the standing crops of lakes and ponds as a basis for predicting hook-and-line yields. Thompson (1941: 213) thought that central Illinois lakes stocked with bass, bluegills, and crappies could give sustained annual hook-and-line yields that would amount to half their carrying capacities. He thought that the corresponding yields for southern Illinois lakes might be close to three-fourths of their carrying capacities. By carrying capacity, Thompson meant the total amount of fish in a lake at saturation point, or the maximum standing crop. Krumholz (1950^:29) estimated that In- diana ponds were capable of giving sus- tained annual yields of "as much as half and perhaps more" of their standing crops. Neither Thompson nor Krumholz spec- ulated on the amount of fishing time that might be required to bring about such yields. We may now compare the hook-and- line yields of the Dixon Springs ponds during the last 3 years of fishing with the standing crops as observed in the 1953 censuses, table 25. The hook-and-line yields were for the most part made up of bass more than 10 inches and bluegills more than 6 inches total length ; the stand- ing crops included all fish, irrespective of size. For each Dixon Springs pond, the 1952 yield alone, as well as the average yield 380 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 for the years 1950, 1951, and 1952, amounted to a much smaller percentage of the standing crop, as observed in Septem- ber, 1953, table 25, than the sustained yield estimates of Thompson and Krum- holz. Percentages were higher in the fer- tilized than in the control ponds. The most heavily fished ponds in 1952 were Hooker, Phelps, and Boaz. The 1952 fish yields in these three ponds were respec- tively 11, 19, and 14 per cent of their observed standing crops. The largest yield in relation to standing crop (28 per cent) was recorded from Lauderdale Pond, where fishing in 1952 was lighter, rather than heavier, than in Hooker, Phelps, or Boaz. If, as is possible, fewer fish were recovered in the rotenone censuses than were actually present, the true percentage values would be even lower than those shown. On the other hand, if unreported yields of fish taken by poachers could be determined and included in the calcula- tions, the percentages for at least some of the ponds might be higher than those shown. Figures representing the 1952 bass har- vest and the numbers and weights of harvestable bass in the ponds at the time of the 1953 census are shown in table 26. Similar figures for bluegills are shown in table 27. If the 1953 fish census gave a close approximation of the population of harvestable fish in 1952, the efficiency of the 1952 fish harvest (the fish caught in relation to the fish present) appears to ha\e been greater for bass in the control ponds and for bluegills in the fertilized ponds. The relations between catch per hour and the abundance of fish of desirable sizes are shown for bass in table 28 and for bluegills in table 29. Data in these tables, especially the ratios expressed, seem to indicate that in the fertilized ponds bass fishing was poorer than would be expected from the numbers of 10-inch or larger bass present and that bluegill fish- ing was better than would be expected from the populations of 6-inch or larger bluegills. Swingle (1945:305) observed that the catch in fertilized ponds was usually greater than would be expected from the increases in their fish-carrying capacities, but he did not say whether his observa- tion applied to both bass and bluegills. He attributed the phenomenon to the blooms of microscopic algae, which he be- lieved helped to conceal the anglers from the fish they were trying to catch. Results of the Dixon Springs experiment indicate that if plankton algae helped to conceal the fishermen from the bass it may also have helped to conceal baits from these fish. We have ordinarily assumed that the pond containing the largest population of Table 25.—Standing crop of largemouth bass and bluegills (fish of all sizes) in the 1953 rotenone census of the six Dixon Springs ponds, and the hook-and-line yield of largemouth bass and bluegills during the last years of the experiment, 1950-1952. Yield data are from table 15, standing crop data from table 24. Pond August, 1960 Hansen et al.: Hook-and-Line Catch 381 fish of desirable sizes is the one likely to prisingly little correlation was found be- provide the best fishing. However, sur- tween numbers of bass and bluegills of Table 26.—The 1952 hook-and-line yield of largemouth bass (number and pounds per acre) as a percentage of the 1953 rotenone census figure in each of the Dixon Springs ponds; also the ratio of fertilized to unfertilized ponds in number and pounds of bass per acre. Basic data are from tables 15 and 24. Pond 382 Illinois N.atural History Survey Bulletin VoL 27, Art. 5 desirable sizes in the several ponds in the 1953 census and the record of fishing suc- cess in the same ponds in the preceding years, tables 26-29. Lauderdale, the pond Table 28.—Number and pounds (per acre) of largemouth bass of at least 10.0 inches total length in the 1953 rotenone census, the hook-and-line catch rate for 1952, and the average annual hook-and-line catch rate for 1950-1952 in each of the Dixon Springs ponds; also the ratio of fertilized to unfertilized ponds in number and pounds of bass per acre and per hour. Basic data are from tables 20 and 24. August, 1960 Hansen et al.: Hook-and-Line Catch 383 that had generally furnished the highest yields and catch rates did not at the time of the census contain the largest popula- tion of fish of desirable sizes, while Phelps, which had consistently furnished poorer fishing than Lauderdale, contained a rela- tively large population of bass and blue- gills of desirable sizes, tables 28 and 29. Assuming that our data were adequate for the comparison just made, we may conclude that our failure to find a closer relationship between standing crops and fishing success was due to one or both of the following reasons : ( 1 ) the stand- ing crops were not the same in all years of the experiment; (2) catch rates were greatly affected by some factor other than the size of the standing crops. FIELD FERTILIZATION AND FISHING SUCCESS The application of chemical fertilizers to fields draining into ponds is sometimes thought to be a benefit to fish production and fishing in such bodies of water. This line of thinking is consistent with the widely accepted idea that fertility of the land comprising the watershed of a lake or river has a profound effect on fish production. Little has been said in the literature of pond fertilization, however, concerning the extent of the benefits to pond fishing that may be derived from watershed treatment. The quantity of fertilizer that might reach a pond in runoff from its watershed would vary from one pond to another and would be difficult to estimate. It would depend, for example, on the size of water- shed, the kind and amount of fertilizer used, and the extent to which it was mixed with the soil as it was applied. It would also depend on the time lapse between fertilizer applications and occurrence of rainstorms, the severity of the storms, the tendency of the soil to erode, and the den- sity of protective vegetation. Part of the fertilizer washed from fields into ponds would later be lost over the pond spill- way. Phosphorus applied to fields as rock phosphate is slowly soluble and, theoret- ically, would be of less benefit to a pond than phosphorus applied as superphos- phate, which is readilv soluble. However, phosphorus applied to fields in the form of superphosphate combines rapidly, in the presence of moisture, with elements in the soil to form slowly soluble calcium phos- phate and relatively insoluble compounds with iron and aluminum. Except for the superphosphate that might be washed from a field into a pond very soon after a soil treatment, the phosphorus carried into a pond from its watershed would be in a relatively insoluble state. Nitrogen and potassium would be present in runoff for a comparatively short time, probably less than a year. Nitrogen is taken up quickly by plants or is lost into the air, while potassium salts tend to leach downward into the soil, where they cannot be re- moved by water running over the soil surface. In the period 1935-1937, previous to the beginning of the study reported here, fields surrounding each of the Dixon Springs ponds were given an application of crushed limestone, and fields surround- ing three of the six ponds (Lauderdale, Wells, and Elam) were treated with superphosphate, table 5. In the course of the study, the water- shed of each pond was again treated with crushed limestone ; for the first time each watershed was treated with rock phos- phate and each watershed except that of Phelps was treated one or more times with chemical fertilizers supplying nitro- gen, phosphorus, and potassium, separately or all three in combination, table 5. Barn- vard manure was applied to one of the "fields. Actual demonstrations of the effect, on fishing success, of crushed limestone ao- plied to ponds or pond watersheds in the United States seem to be lacking. In Europe, Schaeperclaus (1933:162) re- ported that applying lime to pond bottoms protects the health of fish and produces favorable "biological conditions, which react to increase the yield." Because the watersheds of all Dixon Springs ponds received approximately equal applications of limestone, no conclusions can be drawn as to what effect, if any, liming of the watersheds had on fishing success in these ponds. Although phosphorus is generally be- lieved to be important as a pond fertilizer, its value to fishing when applied to pond 384 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 watersheds is difficult or impossible to de- termine from data gathered in the Dixon Springs experiment. The water of Boaz, the only control pond that had no record of superphos- phate, rock phosphate, or complete fer- tilizer application to its watershed until 1949, had a higher phosphate content in 1947 than the water of any of the other five ponds at Dixon Springs, table 3. It is interesting to compare catch rates in Boaz with catch rates in the other con- trol ponds before rock phosphate was ap- plied to part of the Boaz watershed in the fall of 1949. Superphosphate had been applied to the Elam watershed in 1936 and to the Wells watershed in 1937. In the years 1947-1949, bass fishing was not so good in Boaz as in Wells or Elam. In 1948 and 1949, bluegill fishing was slight- ly better in Boaz than in Wells but not quite so good as in Elam, table 30. Table 30.—Catch rates (number and pounds of fish removed per hour of fishing) at Dixon Springs ponds, 1947-1952. Years in which fertilizers were applied to pond watersheds are indi- cated by S (for spring preceding the fishing season) and F (for fall near the end of the fishing season). Data are from table 20. Additional data on watershed fertilization are in table b. Pond Year Largemouth Bass Number Per Hour Pounds Bluegills Per Hour Per Hour Number Pounds Per Hour Fertilized Lauderdale. Hooker . Phelps. Unfertilized Wells Boaz Elam. 1947 August, 1960 Hansen et al.\ Hook-and-Line Catch 385 Bass catch rates improved in Wells Pond in 1951, following fertilizer treat- ment of its watershed in the fall of 1950, and in Boaz Pond in 1950 and 1952, fol- lowing treatment of half of its watershed in 1949 and the other half in 1951, table 30. A drop in the bass catch rate oc- curred in Elam Pond in 1952, after treat- ment of its watershed in the spring of that year. Bluegill catch rates rose slightly in Boaz in 1950, following treatment of half of its watershed in the fall of 1949, and in Wells Pond in 1951, following treat- ment of its watershed the previous fall. The bluegill catch rates improved in Boaz in 1951, following treatment of part of the watershed in the spring of that year, but they declined in 1952, after treatment of another part of the watershed in the autumn of 1951. They declined in Elam in 1952, following application of fertilizer to its watershed in the spring of that year. That the field treatments may not have been the cause of improved bluegill catch rates in Wells is indicated by the trend in catch rates leading up to the field treat- ment of 1950; bluegill catch rates were showing year-to-year improvement before this treatment. Examination of the catch rates for the directly fertilized ponds, Lauderdale, Hooker, and Phelps, in the fishing seasons following both direct and indirect fer- tilization shows that in some cases bluegill fishing was better in the season after a field treatment than before, table 30. However, in most of the cases the im- proved fishing could have been caused by the increased rates of pond fertilization, which were begun in the spring of 1950, rather than by the field fertilization. While the evidence that field fertiliza- tion may have helped fishing in the Dixon Springs ponds is inconclusive, we should perhaps state our conclusion on pond fer- tilization as follows: that, in addition to any improvement in fishing success that might have resulted from watershed treat- ments, there is evidence of improvement in bluegill fishing from direct fertilization of the ponds. The pond owner who strives for better bluegill fishing should therefore not depend upon field fertiliza- tion, but should apply fertilizer directly to the pond. ECONOMICS OF POND FERTILIZATION Some pond owners will be interested in knowing whether the higher fish yields from fertilized ponds offset the cost of the fertilizers. At current (1960) prices quoted by dealers in farm fertilizers, the treatments used on the Dixon Springs ponds in 1947- 1949 would cost approximately $10 per surface acre of water per year; the various treatments used on the three ponds in 1950 would average close to $15 an acre, and the treatments used in 1951-1953 would cost $20 per acre per year. In the following computations, cost for fertiliz- ing the ponds does not include wages for men to do the mixing and spreading. For the 5-year period 1948-1952, the average annual hook-and-line yield (bass and bluegills combined) from the ferti- lized ponds was 48 pounds per acre and from the control ponds 25 pounds per acre, table 16. Although the fertilized ponds were fished somewhat more heavily than the controls, we will assume that most of the 23 pounds greater annual yield of the fertilized ponds was attrib- utable to fertilization. Dressed weights of bass and bluegills would amount to about two-thirds of their live weights. The 23 pounds additional fish yield would there- fore shrink to about 15 pounds in dress- ing. The average yearly cost for fertilizer over the 5 years, 1948-1952, was about $15 per acre; therefore the cost of the extra yield was approximately $1.00 per pound of dressed fish. Using data in table 16, we can make a similar computation for the same period for certain fertilized and unfertilized ponds having nearly equal fishing pres- sures: Lauderdale and Phelps to repre- sent the fertilized ponds, Wells and Boaz the untreated ponds. The total fishing pressure for the two fertilized ponds (164 hours per acre per year) was nearly the same as that for the two control ponds (157 hours per acre per year). The per- acre yield averaged 47 pounds annually from the two fertilized ponds, 28 pounds annually from the two controls, a differ- ence of 19 pounds as live fish or 13 pounds as dressed fish. Here the larger yield of the fertilized ponds was obtained 386 Im.ixois Natural History Survey Bulletin Vol. 27, Art. 5 at a cost of about $1.15 per pound of drciised fish. Usin^ selected data in table 15, we can compare costs for the periods of compara- tively lijiht and comparativel\ heav\- fer- tilizer treatments. In the followintj: com- putations, we have omitted data for 1947, as before, and have also omitted data for 1950, when the three ponds were ferti- lized at three diflferent rates. For 1948 and 1949, the annual yields from the fertilized ponds averaged 15 pounds per acre more than the yields from the con- trols— 10 pounds in terms of dressed fish. Since the annual cost of fertilizer in 1948 and 1949 was about $10 per acre, the ad- ditional yield of dressed fish cost approxi- mately $1.00 per pound. For 1951 and 1952, the annual }ield was 26 pounds greater per acre in the fertilized ponds than in the controls, or 17 pounds dressed weight. 1 he cost of fertilizer during this period was about $20 an acre, making the cost of the additional yield approxi- mately $1.18 per pound of dressed fish. Also, we can estimate the cost per pound of fish attributed to fertilization in each of 4 years by comparing the rec- ords for Lauderdale and Wells, two ponds that were fished at nearly the same rates in most years, especially 1948—1951, and were fished in nearly the same way by the test anglers. As table 15 shows, the per- acre yield of bass and bluegills from Lauderdale was greater than that from Wells bv 20 pounds in 1948, 17 pounds in 1949, 42 pounds in 1950, and 30 pounds in 1951. AVhen we divide the ap- propriate cost figures, $10 an acre in 1948 and 1949, $20 an acre in 1950 and 1951, by the dressed w^eights (13, 11, 28, and 20 pounds), we find that the greater vields from Lauderdale Pond cost ap- proximatelv $0.77 a pound in 1948, $0.91 in 1949, $0.71 in 1950, and $1.00 in 1951. In the vicinity of Dixon Springs, the approximate retail price of dressed carp from the Ohio River is 25 cents a pound, of dressed channel catfish 60 cents a pound. If we were to judge the pond fertilization program at Dixon Springs solely bv the dollar and cents food value of the fish produced, we should conclude that fertilization was not economically justified. However, as a rule pond owners will not base their decisions to fertilize or not to fertilize their ponds solely on economic grounds. Instead, they will base such de- cisions largely on the belief that fertiliza- tion will or will not provide them and their families with more fishing fun. In some instances, the size of the pond, the type of ownership, and the financial position of the owner will influence the decision. For example, a pond of an acre or more might be left unfertilized and a pond of one-half acre might be fertilized, because the smaller pond requires a small- er outlay for fertilizer. A pond owned by a single individual might be left unferti- lized and an equivalent pond owned by a club might be fertilized, because the cost of the club-owned pond can be borne by several members and requires no great out- lay- for any one individual. A pond might be left unfertilized if owned by a person who has a small cash income, or who fishes principally for food, and an equivalent pond might be fertilized if owned by an in- dividual who has a moderate or large cash income, or who fishes principally for sport. As the Dixon Springs experiment shows, ponds seem to dififer in their responses to fertilization ; fertilization might be eco- nomically profitable in some ponds but not in others. ANGLERS' EVALUATION OF PONDS While we have shown that pond ferti- lization was of some benefit to bluegill fishing, there is a question w^hether the differences between fertilized and unfer- tilized ponds in the quality of fishing were great enough to be detected by fishermen. No comments were heard or reported that would indicate that the permit fishermen thought that Hooker and Phelps (the two permit ponds that were fertilized) pro- vided them with better fishing than the unfertilized permit ponds or other unfer- tilized ponds in the neighborhood. The test anglers, who visited all six ponds at weekly intervals, generally had the most success at Lauderdale Pond. Their pref- erences were recorded only after the 1952 fishing season, but it was obvious from our conversations with them that Lauderdale was the favorite among the six ponds. August, 1960 Hansen et al.: Hook-and-Line Catch 387 Charles R. Peters, test angler in 1952, stated that Lauderdale had given him the most pleasure, and he rated the other ponds in the following order: Elam, Phelps, Wells, Boaz, and Hooker. Thus, he ranked the fertilized ponds first, third, and sixth. Examination of his catch rec- ords suggests that his reaction to various ponds might have heen affected more strongly by his success in catching bluegills than by his success in catching bass. Use by the public was somewhat more intensive for the two permit ponds that were fertilized (Hooker and Phelps — especially Hooker) than for the two that were not (Boaz and Elam), table 20. It seems doubtful, however, if catch rates were enough higher for the fertilized ponds to explain their greater popularity with fishermen. Hooker and Phelps ponds were seldom as good as the unfertilized ponds for bass fishing and in some years were not so good as one or more unferti- lized ponds for bluegill fishing. Time spent by permit fishermen in the 6 years of the experiment totaled 924 hours at Hooker, 374 hours at Phelps, 356 hours at Boaz, and 217 hours at Elam. The 6- year average catch-per-man-hour rate for bass in the most heavily fished fertilized pond (Hooker) was below the rate for the least fished control pond open to the public (Elam). The bluegill fishing in Hooker was inferior to that in Elam in terms of number of fish per hour but essentially the same in pounds per hour. The differences in fishing pressure on the four permit ponds may have been re- lated to the various inconveniences fisher- men put up with in getting to and from each pond, such as the number of gates to be opened and closed, the number of fences to be climbed, or the walking dis- tance to the pond. Hooker Pond was the easiest to reach, Elam Pond the most dif- ficult. The inconveniences of reaching Phelps and Boaz were about equal. Quite possibly the availability of shade, ease of walking around the ponds, and general attractiveness of the ponds were factors that made the fishermen decide to fish certain ponds more often than others. Fishermen were not guided to the ferti- lized ponds by news releases or other publicity; only a few of them knew that some ponds were being treated. SUMMARY 1. Six ponds, each of about 1-1^ acres, in southern Illinois were used in an experiment, 1947-1952, to measure the ef- fect of pond fertilization on sport fishing. The effect of fertilization was measured by the sizes of the fish caught, the annual hook-and-line yields, and the catch rates per fisherman-hour. 2. The ponds were stocked with large- mouth bass 6 to 10 inches long (total length) and bluegills about 1 inch long. 3. Three of the ponds were treated with chemical fertilizers containing nitro- gen, phosphorus, and potassium, in some years at rates less than, and in others at rates approximately equal to, the mini- mum rate suggested for ponds in Alabama by Swingle & Smith (1942:16-8). The other three ponds (the controls) were not treated. 4. Creel data were obtained through ( 1 ) public fishing under a permit system that allowed fishermen relatively free ac- cess to four of the ponds and (2) test fishing by anglers (one each year) em- ployed by the Illinois Natural History Survey to fish each of the six ponds for a 2-hour period each week. 5. In 1953, after the ponds had been closed to fishing for a year, the fish in all six ponds were killed with rotenone, and a census was made of the fish population of each pond. 6. Growths of filamentous algae, which appeared on the fertilized ponds in some years, were at times a hindrance to fisher- men. 7. Dense stands of a water plant, C/tara spp., died in the fertilized ponds in the first summer of treatment, while equal- ly dense stands of this plant continued to grow in the control ponds. 8. Blooms of plankton algae were den- ser and more prolonged in the fertilized than in the control ponds. 9. The bass taken from the fertilized ponds averaged smaller but the bluegills larger than those from the control ponds. Bluegills of 8—81/2 inches were more com- mon from fertilized than from unferti- lized ponds. 10. During the 5 years of fishing for both bass and bluegills (in the year after the ponds were stocked, bluegills were too 388 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 small to be kept), the total harvest of bass, by weijjht, was slightly less from the fertilized ponds than from the controls; the bluegill harvest from the fertilized ponds was 2.7 times that from the con- trols. The ratio by weijiht of bass to blue- gills was 1 : 3 in the fertilized ponds, 1 : 1 in the controls. 11. One of the fertilized ponds was superior to all others in both bass and bluegill fishing. The three fertilized ponds ranked 1, 5, and 6 in terms of both num- ber and weight of bass harvested per hour ; 1, 3, and 4 in terms of number of bluegills harvested per hour; and 1, 2, and 3 in terms of weight of bluegills harvested per hour. 12. There is a statistical possibility that through chance alone the fertilized ponds would have ranked better than the controls as bluegill fishing ponds even if no fertilizer had been used. 13. No well-defined year-to-year trend in catch rates for bass was observed dur- ing the experiment. The trend in bluegill fishing in both fertilized and control ponds was toward year-to-year improvement in the first 4 3'ears of bluegill fishing. 14. The two ponds, one fertilized and one control, with the smallest total num- ber of man-hours of fishing had the highest catch rates of harvestable bass. Under equal or nearly equal fishing pressures, bass fishing was in some instances better in the fertilized ponds, in other instances better in the controls; bluegill fishing was consistently better in the fertilized ponds. 15. In September, 1953, the standing crops of bass and bluegills (all sizes) in the three fertilized ponds averaged 292 pounds per acre, in the three controls 238 pounds per acre (ratio 1.2:1). The num- ber of bass 10 inches or longer was ap- proximately the same in fertilized as in control ponds; the number of bluegills 6 inches or longer was 1.3 times as great in fertilized as in unfertilized ponds. 15. The hook-and-line yields of bass and bluegills in 1952, the last year the ponds were fished, were equivalent to 20 per cent of the 1953 standing crops in the fertilized ponds and 16 per cent of the standing crops in the control ponds. 17. Judged by the populations of fish of desirable sizes present at the time of the 1953 census (bass 10 inches or longer, bluegills 6 inches or longer), the hook- and-line harvest appears to have been more efficient for bass in the control ponds and more efficient for bluegills in the fer- tilized ponds. 18. Surprisingly little correlation was found between numbers of bass and blue- gills of harvestable sizes in the ponds in 1953 and the record of fishing success in the preceding years. 19. The fertilization program used at Dixon Springs was of apparent benefit to bluegill fishing but of doubtful benefit to bass fishing; any benefits derived from direct fertilization of ponds were in ad- dition to benefits that may have resulted from fertilization of the pond watersheds. 20. Comparison of yields from the fertilized and unfertilized ponds at Dixon Springs shows that the greater yields of fish from the fertilized ponds were ob- tained at costs estimated to range from $0.71 to $1.18 a pound. 21. Whether the improvement in the quality of bluegill fishing attributed to fertilization was great enough to be de- tected by fishermen is questionable for at least two of the three fertilized ponds. LITERATURE CITED Ball, Robert C. 1948. Recovery of marked fish following a second poisoning of the population in Ford Lake, Michigan. Am. Fish. Soc. Trans, for 1945, 75:36-42. 1949. Experimental use of fertilizer in the production of fish-food organisms and fish. Mich. State Col. Ag. Exp. Sta. Tech. Bui. 210. 28 pp. Ball, Robert C, and Don W. Hayne 1952. Effects of the removal of the fish population on the fish-food organisms of a lake. Ecology 33(1) :41-8. Ball, Robert C, and Howard D. Tait 1952. Production of bass and bluegills in Michigan ponds. Mich. State Col. Ag. Exp. Sta. Tech. Bui. 231. 32 pp. Ball, Robert C, and Howard A. Tanner 1951. The biological e'^ects of fertilizer on a warm-water lake. Mich. State Col. Ag. Exp. Sta. Tech. Bui. 223. 32 pp. Bennett, George W., and Gilbert F. Weiss 1959. Fishing pressure and the empty creel. 111. Wildlife 14(3) :8-9. Brown, C. J. D., and Robert C. Ball 1943. An experiment in the use of derris root (rotenone) on the fish and fish-food organisms of Third Sister Lake. Am. Fish. Soc. Trans, for 1942, 72:267-84. Carlander, Kenneth D., and William M. Lewis 1948. Some precautions In estimating fish populations. Prog. Fish-Cult. 10(3): 134-7. Davis, H. S., and A. H. Wiebe 1931. Experiments in the culture of the black bass and other pondfish. Report of the United States Commissioner of Fisheries for the fiscal year 1930, Appendix IX: 177-203. (U. S. Bur. Fish. Doc. 1085.) Dugan, R. Franklin 1951. Fish production records on some West Virginia farm ponds. N. Am. Wildlife Conf. Trans. 16:403-21. Fehrenbacher, J. B. 1959. Characteristics of the soils on the Dixon Springs Experiment Station of the University of Illinois College of Agriculture. 111. Univ. Agron. Dept. Mimeo. AG1841. 5 pp., map. King, Willis 1943. Lake management studies in the Sandhills Wildlife Management Area. Am. Fish. Soc. Trans, for 1942, 72:204-11. Krumholz, Louis A. 1948. Variations in size and composition of fish populations in recently stocked ponds. Ecol- ogy 29(4) : 401-14. 1950a. Some practical considerations in the use of rotenone in fisheries research. Jour. Wild- life Mgt. 14(4) : 413-24. 1950^. Indiana ponds: their construction and management for fishing. Lake and Stream Sur- vey of the Indiana Department of Conservation, Division of Fish and Game, and In- diana University. (Ind. Univ. Zool. Dept. Contrib. 435.) 35 pp. Maciolek, John A. 1954. Artificial fertilization of lakes and ponds: a review of the literature. \J. S. Fish and Wildlife S:rv. Special Sci. Rep.: Fish. 113. 41 pp. Mortimer, C. H., and C. F. Hickling 1954. Fertilizers in fishponds: a review and bibliography. Her Majesty's Stationery Office, London. Colonial Office Fish. Pubs. 5. 155 pp. Neess, John C. 1949. Development and status of pond fertilization in central Europe. Am. Fish. Soc. Trans, for 1946, 76:335-58. Patriarche, Mercer H., and Robert C. Ball 1949. An analysis of the bottom fauna production in fertilized and unfertilized ponds and its utilization by young-of-the-vear fish. Mich. State Col. Ag. Exp. Sta. Tech. Bui. 207. 35 pp. ' ' Schaeperclaus, Wilhelm 1933. Textbook of pond culture: rearing and keeping of carp, trout and allied fishes. (Trans- lated from the German by Frederick Hund.) U. S. Fish and Wildlife Serv. Fish. Leaflet 311. 260 pp. Smith, E. v., and H. S. Swingle 1939. The relationship between plankton production and fish production in ponds. Am. Fish. Soc. Trans, for 1938, 68:309-15. [389] 390 Illinois Natural History Survey Bulletin Vol. 27, Art. 5 1942. The use of fertilizer for controlling several submerged aquatic plants in ponds. Am. Fish. Soc. Trans, for 1941, 71:94-101. Smith, Lloyd L.. Jr., and John B. Movie 1945. Factors inHuencing production of yellow pikcperch, Stizostcdion vitrrum vitreum, in Minnesota rearing ponds. Am. Fish. Soc. Trans, for 1943, 73:243-61. Smith, M. W. 1952. Fertilization and predator control to improve trout production in Crecy Lake, New Brunswick. Can. Fish Cult. 13:33-9. 1954. Planting hatcherv stocks of speckled trout in improved waters. Can. Fish Cult. 16:1-5. Surher, Eugene W. 1945. The effects of various fertilizers on plant growths and their probable influence on the production of smallmouth black bass in hard-water ponds. Am. Fish. Soc. Trans, for 1943, 73:377-93. 1948a. Fertilization of a recreational lake to control submerged plants: effects of fertilization program upon bathing, boating, fishing. Prog. Fish-Cult. 10(2): 53-8. 1948/;. Increasing production of bluegill sunfish for farm pond stocking. Prog. Fish-Cult. 10(4) : 199-203. Swingle, H. S. 1945. Improvement of fishing in old ponds. N. Am. Wildlife Conf. Trans. 10:299-308. 1947. Experiments on pond fertilization. Ala. Poly. Inst. Ag. Exp. Sta. Bui. 264. 34 pp. Swingle, Homer S., and E. V. Smith 1941. The management of ponds for the production of game and pan fish. Pp. 218-26 in A symposium on hydrobiology. University of Wisconsin Press, Madison. ix-(-405 pp. 1942. Management of farm fish ponds. Ala. Poly. Inst. Ag. Exp. Sta. Bui. 254. 23 pp. Thompson, David H. 1941. The fish production of inland streams and lakes. Pp. 206-17 in A symposium on hydro- biology. University of Wisconsin Press, Madison, ix + 405 pp. Thor, A. U., and W. C. Jacob 1955. Percentage of soil samples by counties testing very low, low, slight, medium, high, and verv high in Illinois, 1955. 111. Univ. Agron. Dept. Mimeo. AG1750a. 4 pp. Zelter, Howard D. • j • 1953. Nitrogen and phosphorus concentrations in fertilized and unfertilized farm ponds in central Missouri. Am. Fish. Soc. Trans, for 1952, 82:281-8. Some Publications of the Illinois Natural History Survey BULLETIN Volume 26, Article 3.—Natural Availability of Oak Wilt Inocula. By E. A. Curl. June, 1955. 48 pp., frontis., 22 figt., bibliog. Volume 26, Article 4.—Efficiency and Selec- tivity of Commercial Fiahing Devices Used 00 the Mississippi River. By William C. Starrett and Paul G. Barnickol. July, 1955. 42 pp., frontis., 17 figs., bibliog. Volume 26, Article 5.—Hill Prairies of Illi- nois. By Robert A. Evers. August, 1955. 80 pp., frontis., 28 figs., bibliog. Volume 26, Article 6.—Fusarium Disease of Gladiolus: Its Causal Agent By Junius L. Forsberg. September, 1955. 57 pp., frontis., 22 figs., bibliog. Volume 27, Article 1.—Ecological Life History of the Warmouth. By R. Weldon Larimore. August, 1957. 84 pp., color frontis., 27 figs., bibliog. Volume 27, Article 2.—A Century of Biological Research. By Harlow B. Mills, George C. Decker, Herbert H. Ross, J. Cedric Carter, George W. Bennett, Thomas G. Scott, James S. Ayars, Ruth R. Warrick, and Bessie B. East. December, 1958. 150 pp., 2 frontis., illus., bibliog. $1.00. Volume 27, Article 3.—^Lead Poisoning as a Mortality Factor in Waterfowl Populations. By Frank C. Bellrose. May, 1959. 54 pp., frontis., 9 figs., bibliog. 50 cents. Volume 27, Article 4.—Food Habits of Migra- tory Ducks in Illinois. By Harry G. Ander- son. August, 1959. 56 pp., frontis., 18 figs., bibliog. 50 cents. CIRCULAR 42.—Bird Dogs in Sport and Conservation. By Ralph E. Yeatter. December, 1948. 64 pp., frontis., 40 figs. 48.—Diseases of Wheat, Oats, Barley, and Rye. By G. H. Boewe. June, 1960. 157 pp., frontis., 56 figs. Single copies free to Illinois resi- dents; 25 cents to others. BIOLOGICAL NOTES 33.—A New Technique in Control of the Houi Fly. By Willis N. Bruce. December, 195 8 pp., 5 figs. 34.—White-Tailed Deer Populationt in III nois. By Lysle R. Pietsch. June, 1954. : pp., 17 figs., bibliog. 35.—An Evaluation of the Red Fos. I Thomas G. Scott July, 1955. (Secoi printing.) 16 pp., illus., bibliog. 36.—A Spectacular Waterfowl Migratit Through Central North America. By Frai C. Bellrose. April, 1957. 24 pp., 9 figs., hi Hog. 37.—Continuous Mass Rearing of the Eur pean Corn Borer in the Laboratory. 1 Paul Surany. May, 1957. 12 pp., 7 fig bibliog. 38.—Ectoparasites of the Cottontail Rabbit Lee County, Northern Illinois. By Lewis Statmard, Jr., and Lysle R. Pietsch. Jui 1958. 20 pp., 14 figs., bibliog. 39.—A Guide to Aging of Pheasant Embryi By Ronald F. Labisky and James F. Opsal September, 1958. 4 pp., illus., bibliog. 40.—Night-Lighting: A Technique for C« turing Birds and Mammals. By Ronald Labisky. July, 1959. 12 pp., 8 figs., biblic 41.—Hawks and Owit: Population Tren From Illinois Christmas Counts. By Richa R. Graber and Jack S. Golden. March, 19< 24 pp., 24 figs., bibliog. 42.—Winter Foods of the Bobwhite in Southe Illinois. By Edward J. Larimer. May, 19( 36 pp., 11 figs., bibliog. MANUAL 3.—Fieldbook of Native Illinois Shrubs. 1 Leo R. Tehon. December, 1942. 307 p 4 color pis., 72 figs., glossary, index. $l.\ 4.—Fieldbook of Illinois Mammals. By Dons F. Hoffmeister and Carl O. Mohr. Jul 1957. 233 pp., color frontis., 119 figs., gl( sary, bibliog., index. $1.75. List of available publications mailed on request. 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