Bulletin ILi/llslOIS NATURAL HISTORY SURVEY lh« Stale of lllinoii Stocking and Sport Fishing at Lake Glendale (Illinois) DONALD F. HANSEN SEP 15 1966 ^^^^^^mm^^^^^^ SEP 23 ms STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION NATURAL HISTORY SURVEY DIVISION Urbana, Illinois ILLINOIS NATURAL HISTORY SURVEY Bulletin Volume 29, Article 2 p , h h a .^ , ,' Printed by Authority of July/ 1966 the State of Illinois Stocking and Sport Fishing at Lake Glendale (Illinois) DONALD F. HANSEN STATE OF ILUNOIS DEPARTMENT OF REGISTRATION AND EDUCATION NATURAL HISTORY SURVEY DIVISION Urbana, Illinois STATE OF ILLINOIS DEPARTMENT OP REGISTRATION AND EDUCATION BOARD OF NATURAL RESOURCES AND CONSERVATION John C. Watson, Chairman; Thomas Park, Ph.D., Biology; L. L, Sloss, Ph.D., Gcologij; Bogek Adams, Ph D D Sc Chemistry: Robekt H. Anderson, B.S.C.E., E iigineering ; Charles E. Olmsted, Ph.D.. Forestry; W. L. Everitt, E.E., Ph.D., Representing the Presulent of the University of Illinois; Delyte W. Morris, Ph.D., President of Southern Illinois University. NATURAL HISTORY SURVEY DIVISION, Urbana, SCIENTIFIC AND TECHNICAL STAFF H.uiLow B. Mills, Ph.D., Chief Herbert H. Ross, Ph.D.. As:e cialist William R. Edwards, M.S., Associate Wildlife S/"- cialist William W. Cochran, Jr., Assistant WUdlife S/"- cialist Helen C. Schultz, B.S., Technical Assistant Emory F. Bowers, B.S.. Technical Assistant Lucinda Janis, Technical Assistant Judith A. Kadner, B.S., Technical Assistant Robert D. Crompton. Field Assistant William J. Francis, Ph.D.. Research Associate* J.\CK A. Ellis. M.S., Research Associate* James A. Bailey. M.S., Research Associate* Gerald G. Montgomery, M.S.. Research Associate* William L. Anderson. M.A., Research Associate* George B. Joselyn, M.S.. Research Associate* Gerald L. Storm, M.S., Field Ecologist* Ronald L. Westemeier, B.S., Research Associate* St.\nley L. Etter, M.S.. Research Assistant* Roger J. Siqlin, M.S., Research Assistant* Robert E. Hawkins, B.S., Research Assistant* Larrv D. M.\rtoglio. M.S., Research Assistant* Keith P. Dauphin, Project Assistant* Section of Publications and Public Relations Owen F. Glissendorf, M.S., Technical Editor and * Head Blanche P. Y'dung, B.A., Associate Technical Edi- tor Robert M. Zewadski. M.S., Assistant Technical Edi- to-r Wilmer D. Zehr, Technical Photographer William L. Taylor, Technical Assistant Section of Aquatic Biology George W. Bennett. Ph.D., AqiuUic Biologist and Head William C. Starrett, Ph.D.. Aqiuitic Biologist R. W. Larimore, Ph.D., Aquatic Biologist David H. Buck, Ph.D., Associate Aqitatic Biologist Robert C. Hiltibran, Ph.D.. Associate Biocheynist Donald F. Hansen, Ph.D., Associate Aquatic Biol- ogist William F Childers, Ph.D., Assistant Aq^Mtic Biologist Paul A. Fishman. B.S., Research Assistant Maryfran Martin, Technical Assistant Claude Russell Rose, Field Assistant Charles F. Thoits, III, B.A., Research Associate* David L. Thomas. B.S., Research Assistant* CONSULTANTS- Herpetology, Hobart M. Smith, Ph.D., Professor of Zoology, University of Ulinois ; Parasitology Norman D Levine. Ph.D., Professor of Vetei-iivary Parasitology and Veterinary Research. University of 'uiinois; Wildlife Research. Willard D. Klimstra, Ph.D., Professor of Zoology and Di- rector of Co-operative Wildlife Research. Southern Hlinois University; Statistics, Horace W. Norton. Ph.D.. Professor of Statistical Design and Analysis, University of Illinois. Technical Library Doris F. Dodds, B.A., M.S.L.S., Patricia F. Stenstrom, B.A., Technical Librarian 4 Technical Librarian- M.S.L.S., Assistant My of Illinois, Agricultural Extension' Service IIlino"is Department of Conservation, National Science Foundation, United States Depart- ment of Agriculture, United States Fish and Wildlife Service, United States Public Health Ser\'ice. and others. Employed on co-operative projects with one of several agencies: Universi . _ 'n:--:- T» * * „* nn^cni-Troti^i, Natlonal Science Foundation, United States Depart- Contents Acknowledgments 106 Lake Glendale 106 Study Procedures at Lake Glendale 109 The 1940 Stocking 109 The 1946 Stocking 110 Creel Census Ill Fishing Regulations Ill Length Measurements 112 Population Censuses 112 The 1946 Census of All Species 112 The 1950 Census of the Bass Population 117 Study Procedures at Pounds Lake 120 Quality of Fishing Following Two Programs of Stocking 121 Analysis of Bass Fishing 122 Analysis of Bluegill Fishing 133 Fishing for Warmouths and Green Sunfish 137 Efforts to Impro\'e Fishing 138 Growth of Fishes 138 Growth of Original Bass 139 Growth of Bass in New Broods 140 Growth of Original Bluegills 144 Growth of Bluegills in New Broods 145 Census of Population and Standing Crop 145 Factors That Determine Fishing Effort 148 Discussion 150 Summary 152 Literature Cited 155 Index 157 This report is printed Inj authority of the State of Illinois; IRS Ch. 127, Par. 58.12. It Li a conlrihtition from the Section of A E c c ^ II O . o- c •- o £^ ,- E ° c .il vt Ui ° «) -° i £ -o 3 C o o oi a; ° E is Z o ? ^ tc 118 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 that remained in the channel are shown in Table 2. In the marking operation, 154 bass measuring 7 to 12.5 inches were marked by removal of the right pectoral fin. The area of skin from which a scale sample was removed served as a mark for each of 79 bass longer than 12.5 inches. The population estimates of bass of the two size categories shown in Tables 3 and 4 were obtained from the Schna- bel formula cited by Ricker (1942:231) for estimating the size of a population Table 3.—Estimates of number of 7— 12. 5-inch largemouth boss remoining in Lake Glendole after part of tfie population had been removed in the draining operation of October, 1950. The Schnabel method of computing populations from recovery of marked fish was used. The bass in only the first four samples were marked. Because of the length of time the marked fish hod to mix with the unmarked fish, the lost populotion estimate is assumed to be the most nearly accurate. This estimate {2,415 fish) is only slightly lower than the one obtained from sample 5 (before 439 bass in samples 5, 6, and 7 had been withdrawn) and was used in calculating the total population (Table 2). July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 119 while marking is in progress. The pop- ulation at any one sampling time is 1 , , r , ^ (AB) computed by the tonnula ^,' . , in which A is the total number of fish in the sample, B is the number of marked fish in the entire population when the sample is taken, and C is the number of marked fish in the sample. The last in each series of population estimates (for example, the estimates based on Sample 9, Table 3, and Sample 11, Table 4) is assumed to be the most nearly accurate in the series. The samples used in the mark-and- recovery estimate were obtained with an electric shocker carried in a boat ( Fig. 5 ) ; the current was furnished by a 115-volt, 11-ampere generator. Sam- ples were obtained in several runs, each covering about one-sixth to one-half of the 1,300-foot section of channel. All parts of this 1,300-foot section were covered in the course of the sampling. Because of the high turbidity of the water, only the fish that rose to the surface could be collected. Fish of each of the two size categories shown in Tables 3 and 4 were not observed on all sampling trips with the shocker; hence the difference in number of sam- ples shown in these tables. In other tests of the accuracy of mark-and-reco\ cry estimates of large- mouth bass populations, a high degree of accurac)' was reported in one pond (Carlander & Moorman 1956:663), moderate accuracy in three ponds, especially for bass more than 1 year old (Buck & Thoits 1965:606-607), and considerable inaccuracy in two ponds (Kruniholz 1944:290; Hundley 1954:167). The degiee of accuracy of the 1950 mark-and-recovery estimate of bass at Lake Glendale is perhaps fairly liigh due to the fact that the bass were concentrated in a small volume of water instead of being spread oxer the entire 82 acres. Because the bass were concentrated in a small space, there should have been the good mixing of marked and unmarked fish that is es- sential to obtaining close estimates of populations. A much larger percentage Fig. 5.—Electrofishing for a mork-and-recovery estimote of the number of lorgemoutf> boss re- maining in tfie stream channel after most of the water in Lake Glendale had been drained oflF in October, 1950. 120 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 of bass over 12.5 inches than below tliat length were marked, and the ac- curacy of die estimated population was therefore probably better for the larger bass than for the smaller ones. STUDY PROCEDURES AT POUNDS LAKE At the time Lake Glcndale was stocked in April, 1940, the Natural His- tory Sun'ey also stocked Pounds Lake (Fig. 6), a 32-acre lake that had just been built on U.S. Forest Service land in Gallatin County, 40 miles northeast of Lake Glendale. A water sample from Pounds Lake, collected in May, 1963, had a total hardness of 26 ppm, which was similar to that of Lake Glendale and the ponds at Dixon Springs. Pounds Lake was stocked at the rate of 1.7 adult bass and 3.6 adult bluegills per acre. The fish were of the same sizes as those used in stocking Lake Glendale. (Lake Glendale was stocked at the rate of 0.9 adult bass and 2.6 adult bluegills per acre.) The Pounds Lake stock (55 largcmouth bass and 120 bluegills), like the stock for Lake Glendale, came from Lake Chautauqua near Havana, Illinois. A rotenone treat- ment of the stream that feeds Pounds Lake, applied in 1939 before the water was impounded, failed to eliminate all of the green sunfish and yellow bull- heads, Ictuhirits luitalis (Lesueur), in the stream. These species reproduced in the lake but were never very abun- dant. Five hundred mosquitofish, Garn- biisia affinis ( Baird & Girard), were re- leased in Pounds Lake by the local forest ranger in 1940. The gizzard shad, Dorosoma cepedi- anum (Lesueur), a favorite forage fish of bass, was present in Pounds Lake in H Fig. 6.—Fishermen with bluegills at Pounds Lake, May 16, 1942. July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 121 the fall of 1947 when the lake was drained, but scales examined from shad collected at that time suggest that this fish was introduced late in 1946 or early in 1947. Pounds Lake, like Lake Glendale, was opened to fishing on May 15, 1942. Subsequently, except in 1943 and 1946 when the length of the fishing season at Lake Glendale was extended, the two lakes were opened to fishing each year on May 15 (the first day of the largemouth bass season in southern Illinois) and closed some time in Sep- tember. Tlirough the cooperation of the Pounds Lake boat concessionaire, creel censuses were made for 6 weeks in 1943 and dirring most of the next three fish- ing seasons. The Pounds Lake record included numbers of fish kept by boat fishermen, but it did not include the weight of the fish kept or any data on baits. This record is assumed to have covered most of the fishing that was done during the periods shown in Table 8. Tlie census co\'ered neither pri\'ate boats nor bank fishing, but Es- den Jerrels, the concessionaire, pointed out that \'ery few private boats were brought to the lake in the 1940's and that bank fishing at that time was very light. In the years 1943-1945, a report was made out for each boat party, including tlie parties that returned without fish; it showed the number of fishermen in each boat and the number of each species of fish kept by the party. In the 1946 season, records were made for only those trips in which some member of the boat party kept one or more fish; therefore, the catch per trip for that season was not computed. QUALITY OF FISHING FOLLOWING TWO PROGRAMS OF STOCKING The success of a fish-stocking pro- gram may be measured by the quality of fishing as well as by fish-growth rates, size of standing crop of fish, and "balance" of species in the population. The quality of fishing for bass and bluegills was markedly different in the two study periods at Lake Glendale. Bluegill fishing was decidedly better in the first period, after the lake had been stocked hghtly in 1940 and kept closed to fishing for 2 years. Bass fishing was better in the second period, after the lake had been stocked more heax'ily in the fall of 1946 and opened to fishing the following spring. The 2-year delay in opening the lake after the first stocking was necessitated by the small number of fish used in the stocking. The first period, besides being the better of the two for bluegill fishermen, was also better for those fishermen who were not concerned about the kind of fish they caught; this period was the better in percentage of trips resulting in the capture of one or more fish (Table 5), in the total number and weight of fish harvested annually, and in the average number and weight of fish harvested per trip (Tables 6 and 7). Striking differences between the two study periods were found in the ratios of total weight of bass to the total weight of bluegills har\'ested annually. Following the 1940 stocking, annual yields of bluegills (by weight) were 4 to 12 times as large as bass yields, while, for the first three seasons follow- ing the 1946 stocking, bluegill yields were smaller tlian bass yields (Table 7 ) . But the catch of bluegills increased each year after 1947 until in 1950 the weight of bluegills finally exceeded that of bass. In three small unfertilized ponds at Dixon Springs (Hansen et al. 1960:365), the yields of bass were ap- proximately the same as the yields of bluegills, whereas in three small fertil- ized ponds in the same study area the yields of bluegills were three times those of bass (each average based on three ponds fished for 5 years ) . The 1940 introductions of fish at Pounds Lake and at Lake Glendale, with fewer than two adult bass and four adult bluegills per acre, was fol- 122 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 Table 5.—General information concerning sport fishing at Lake Glen dale in the years following the 1940 stocking (first period) and after the 1946 stocking (second period). The data were derived from creel censuses. First Period Second Period Type of rnformation 3S July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 123 2-0 .. o O V O v -2 -o ± 8 0) .E i ^ D ^ D -E c j: °> « -D "^ o - ^ .;2 'w 1 U 1_ V 0) '. "- -D O v E ^ . — O — O C5 ° =c2 fe. i^'o> lO ^ 124 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 — O •^ E O = o o= J3 o _ T3 -SI i? a «= o ^ i_ o -o~ E U 3 Q. C '-3 -- 2e 2 <^ 05 ' . lO o July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 125 126 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 40 20- 60- 40- I July, 1966 Hansen: Stocking and Sport Fishinc at Lake Glendale 127 Table 9.—Hook -and- line catch rotes in southern Illinois waters in which different stocking pro- cedures were used.* 128 Illinois Natural History Survey Bi'lletin Vol. 29, Art. 2 Like the total bass hanest (Table 6), the han'est of bass with artificial baits was considerably better in 1947-1950 than in the earlier period (Table 10). In the fishing done with worms, the bass har\'est showed some improve- ment in the second period, but not one that fishennen would ha\'e noticed. In most years of each period, fly rod lures produced the best bass fishing in terms of number of fish harvested per trip, but casting rod lures produced the best bass fishing in terms of weight of fish harvested per trip ( Table 10 ) . The years 1947 and 1948 were the best in either period for catching bass on flies Fig. 8.—One fisherman's siring of largemoulh bass caught at Lake Glendale on the day the laler cent of the bass harvested in 1942 were caught on the first day of the season; 75 per cent were caught during the first 15 days of fishing. Most of the bass har\'ested the first day were caught during the first 4 hours. The good fishing started at 6 am and ended with the arrixal of a cold front and a shaip droD in temperature at about 10 AM. The early season declines in other years, most noticeable in 1948 and 1949, were not as sharp as in 1942. The phenomenon of a high rate of catch of bass at the beginning of a fisliing season, followed by a rapid de- cline, has been reported at other lakes by Dill (1946:59-60), Bennett (1954: 256-261), and Bowers & Martin (1956: 8-9 ) . Many of the fishermen at Lincoln Trail Lake, east-central Illinois, on the opening day of the 1958 fishing season reported that they caught the majority of their largemouth bass in the first 2 Table 10.—Catch of largemouth boss, and catch per trip, on various types of boit at Lake Glendale. Fishing with spinning rods and spinning lures had not become popular at the time of this study. 130 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 Table 11.—Harvest of largemouth boss at Lake Glendale during first 15 days of the 1942 season. The lake was closed to fishing on Monday of each week. Julv, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 131 ulation of fish of han'estable sizes. Eschmeyer (1942:110) estimated that the harvest of game fish at Norris Res- en'oir in June, 1940, was about 14 per cent of the population of legal-size game fish at the beginning of the fish- ing season and diat the harvest for the entire fishing season (June-November) was only about 20 per cent of this pop- ulaHon. 'Bennett (1954:259-260) found at Ridge Lake that the best bass fishing in each of four seasons occurred on the morning of the opening day and dropped off shar^Dly after only a small proportion of the bass population had been caught. The real reason for the drop in bass fishing success in the course of the opening day of fishing at Lake Glen- dale remains unknown. Several factors may ha\'e been involved. A substantial number of the least wary bass, the most Table 13.—Size distribution of lorgemouth boss caught at Lake Glendale by Natural History Survey test fishermen, 1944—1950. Most of the fishing was done with fly rods and small popper flies. An asterisk (') following a number indicates recorded fin-clipped bass of the 1946 stocking, except as noted for 1948. The legal length of bass at the time of this study was 10 inches. The 10-inch class (below broken line in table) includes fish measuring 9.8—10.2 inches. Length Clann, 132 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 Table M.—Size distribution of lorgemouth boss caught at Lake Glendale by sport fistiermen under the permit system, as indicated by a sampling of the boss caught. Meourements in 1942 and 1944 were made by Natural History Survey biologists, those in 1 947—1 950 by creel-census clerks. The size dis- tributions of boss caught by test fishermen are shown in Table 13 and the total bass harvest in Table 6. July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 133 age weight of the bass taken on flies was greater in the second period (Table 12). In 1948, the average weight of the bass taken on plugs was about the same as that of the bass taken on flies or womis. In most other years the bass caught on plugs averaged about a quar- ter pound to more than a pound heavier than those caught on flies or worms. Although the difference between periods in ax'erage weights of bass har- vested was small (Table 12), tliere were important differences between One reason the test fishermen caught very few large bass may have been that they fished almost exclusively with small flics and poppers. Also, the test fishermen started fishing 2 to 4 weeks later in the season than other fishermen, which in the opinion of some fishermen in soutlicrn Illinois re- duced their chances of catching large bass. According to reports made by sport fishermen to the census clerks, more small bass were caught and thrown back in the lake in 1942-1946 than in Table 15.—Number of largemouth bass kept and number thrown back by fishermen at Lake Glen- dale. 134 Illinois Natx'ral History Survey Bulletin Vol. 29, Art. 2 lakes in southern Illinois. The bluegill han'est per trip at Lake Glendale in this period was about the same as at Pounds Lake, although the best single year was observed at Pounds (Table 8). Bluegill fishing at Lake Glendale in 1943-1946 ( the 4 best years ) was not as good as bluegill fishing in three un- fertilized ponds near Dixon Springs (Hansen et al. 1960:368-369), but it was better than that recorded in 1961 at two other southern Illinois lakes, namely, Murphysboro (160 acres) and Horseshoe (2,400 acres) (Lopinot 1962: 20-21 ) . The catch rates reported for Fig. 9.— Bluegills caught at lake Glendale on opening day, May 15, 1942. July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 135 bluegills taken on flies were better at (Table 16). The stocking rates used at Lake Glendale in 1943-1946 (Table 16) Muq>hysboro, Crab Orchard, and than at Lake Murphysboro in 1955 Horseshoe lakes are not known. The (Lewis et al. 1957:35). The catch rates three lakes contained a greater variety reported for bluegiUs taken on cock- of fish species than Lake Glendale. roaches at Crab Orchard Lake ( 61 A\'erage weights of bluegills kept by hours of fishing) were considerably bet- Lake Glendale fishermen were similar ter than the catch rates for bluegills in the two periods (Table 17). Only taken on flies, worms, or miscellaneous in 1942 and 1948 did the bluegills aver- baits at Lake Glendale in any year age more than 0.25 pound each. The Table 16.—Catch of bluegills and catch per trip on various types of bait at Lake Glendale.* First Period Second Period 136 Illinois Natural History Survey Bulletin- Vol. 29, Art. 2 length distributions of bluegills caught most of the large bluegills caught by by test fishermen is shown in Table 18. sportsmen in 1942 and 1943 were fish (No record was made of lengths of belonging to the first brood produced bluegills caught by other fishermen.) in the lake (in 1940). However, the The length distribution of bluegills largest bluegills caught in these years captured in hoop nets during the early —some measuring up to 10 inches — spring, 1941-1950, is shown in Table were from the original stock ( 215 blue- 24. gills). All of the bluegills harvested by In each year after the light (1940) sportsmen in 1947 were fish used in the stocking, the number of bluegills kept 1946 stocking, and the largest bluegills exceeded the number thrown back in har\'ested in 1948 and 1949 were from the lake (Table 19). Not until the the 1946 stock (Table IS). In contrast, fourth year after the hea\'ier (1946) Table 18.— Size distribufions of bluegills caught at Lake Glendale by Natural History Survey test fishermen, 1944—1950. An asterisk (') following a number indicates recorded fin-clipped bluegills of the 1946 stocking. Most fish were caught with fly rod and small popper flies. July, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 137 stocking did the number kept exceed the number thrown back. In each year, the percentage of the catch thrown back was lower for bkicgills than for bass (Tables 15 and 19). Bluegill catch rates at Lake Glendale reached a plateau in the fourth grow- ing season ( 1943 ) after the 1940 stock- ing (Table 6). The catch rates showed steady impro\'ement through the fourth growing season ( 1950 ) after the 1946 stocking. As late as 1950, however, the quality of bluegill fishing during the second period was not up to that ob- ser\'ed in the better years of the first period. At Pounds Lake, bluegill catch rates rose to a peak in the fifth growing season ( 1944 ) after the 1940 stocking (Table 8). In the three unfertilized ponds near Dixon Springs (Hansen et al. 1960:384), there was a tendency toward a gradual improvement in blue- gill catch rates, with peak rates coming in the fifth or sixth growing season after the stocking. Annual harv'est rates of bluegills, in number per trip at Lake Glendale, were one and a half to five times as good with worms as with flies (Table 16). Unexpectedly large numbers of bliiesills were caught by sport fisher- men and test anglers while plug fishing for bass. For example, in 1950, 101 bluegills were caught on plugs in 424 trips and 141 on flies in 201 trips (Table 16). Fishing for Warmouths and Green Sunfish Since the numbers of warmouths and preen sunfish introduced into Lake G'endale are unknown, and the num- bers that sur\'i\'ed after the 1946 census are also unknown, a comparison of cjuality of fishing for the years 1942- 1946 and 1947-1950 would have little meaning in this evaluation of stocking rates. The numbers of warmouths caught increased from year to year in 194.3-1946 and again in 1948-1950, but the species did not become important during either period (Table 6). The numbers of green sunfish har- vested by fishennen declined in the period 1942-1946 from an initial high in 1942 but increased in the later period (Table 6). More green sunfish of harvestable sizes were reported in the 1946 creel (Table 6) than were found in the population census at the end of the fishing season (Table 27). At no time was fishing as productive for warmouths or green simfish as for bluegills (Tables 6 and 7). In 1942, the weight of the green sunfish harvest was nearly equal to the weight of the har- vest of largemouth bass (Table 7). It would appear from the number of har- \estable fish in the population at the time of the census in 1946 (Table 27) and the number harvested by fisher- men in that year that green sunfish were more \'ulnerable to capture than any of the other species at Lake Glen- dale; the green sunfish were followed in order of vulnerability by the large- mouth bass, bluegill, and warmouth. Larimore (1957:70) found that in one Illinois pond largemouth bass of the original stock were more susceptible to capture than warmouths of the orig- inal stock. Lake Glendale warmouths showed a preference for live baits. In 1946, 842 fishermen using worms caught 205 war- mouths, while 222 fishennen using arti- ficial flies caught only 8 warmouths (not shown in tables). Larimore (1957: 69) stated that the warmouth in most of its range is taken more commonly on natural baits than on artificial baits. The green sunfish at Lake Glendale apparently showed a preference for artificial flies. In 1943, the first year in which bait records were kept at Lake Glendale, 162 fly fishermen caught 159 green sunfish, whereas 664 worm fish- ermen caught 227. Howexer, most of the fly fishing was done along the margin of the lake, a region preferred by green sunfish, whereas a consider- able part of the worm fishing was done offshore in water deeper than that u.su- ally frecjuented by green sunfish. 138 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 EFFORTS TO IMPROVE FISHING Following the light stocking at Lake Glendale in 1940 and before any thought had been given to a new stock- ing (as finally carried out in the fall of 1946), a number of experimental at- tempts were made to impro\'e fishing in the lake. None of these attempts was effective. For example, in early September, 1944, when the lake level stood 19 inches below full stage, the level was dropped 40 inches more. This drop resulted in a 22 per cent re- duction in the lake area, from a normal area of 82 acres to 64 acres. This is not as much of a reduction as is recom- mended for a successful drawdown (Bennett 1962:160). Tlie lake level re- mained low through the fall months, rising only 6 inches during a period of 12 weeks, September S through No- vember 30; the lake refilled during the winter. It had been speculated that re- moval of the water from the fringe of cattails surrounding the lake would expose young bluegills to predation by bass and increase the growth rates of the bluegills (through reduced compe- tition for food). However, the young bluegills received protection from underwater plants, particularly chara, as the water dropped below the level of the cattails. Little change could be seen in sizes of bluegills caught after this slight reduction in water level. Bluegills larger than 6 inches caught by test fishermen (Table 18) a\'eraged 6.6 inches in the summer of 1944 before the drawdown, 6.75 inches in 1945, 6.8 inches in 1946 (these averages not shown in table). Furthermore, bluegill catch rates changed only slightly in the 2 years after the reduction (Tables 6, 7, and 16). The reduction in water level was not followed by changes in catch rates of bass or in sizes of bass caught (Tables 6, 7, 10, and 13). Several changes were made in Lake Glendale fishing regulations in the hope that bass harvests might be improved. The restriction against use of live min- nows was dropped for the 1943 season; there was httle indication that min- nows were more eff^ective than other bass baits. In 14 trips in which min- nows were the only bait used, fisher- men caught only 2 bass of legal size. In 231 trips in which plugs were used in 1943, fishermen caught and kept 47 bass (Table 10). In another manage- ment attempt in 1943, the fall fishing season was extended to include the 12 Sundays in the period September 12 through November 28. During this special season of Sunday fishing, 32 fishermen using plugs harvested 12 bass weighing a total of 8 pounds. During the regular season. May 15 through September 11, 199 fishermen using plugs har\'ested 35 bass weighing a total of 63 pounds. The number of bass caught per trip was therefore much better during the special season than during the regular season, while weight per trip was slightly better dur- ing the regular season. During a special open season early in the spring of 1946, when fishing was allowed on the five Sundays preceding the regular May 15 opening, 155 fishermen using plugs har- vested 14 bass having a total weight of 27 pounds. During the regular 1946 season. May 15 through September 22, 179 fishermen using plugs harvested 6 bass weighing 15 pounds. GROWTH OF FISHES Because good sport fishing depends on the availability of desirable sizes of fish, the growth in both the original stock and the new broods was studied at Lake Glendale. Year-to-year growth was studied from changes in length- frequency distributions and, to a lim- ited extent, from examinations of scale samples. The scale samples used in making age determinations were col- lected either before or near the end of the growing season; thus, most of the uncertainties in fish ages caused by var- iations in time of annulus formation were avoided. In the first study period, when few largemouth bass were harvested (Table i Julv, 1966 Hansen: Stocking and Sport Fishing at Lake Glendale 139 14), most of the bass in the 12-15.5- inch range were "cannibals"—excep- tionally fast-growing indi\iduals that derive their name from the supposition (at least correct for hatchery-reared bass) that they feed principally on their slower-growing brood mates. At the start of fishing in the second study period, the bass har\'est was made up principally of fast-growing fish of the 1946 stock; toward the end of the period, they were made up principally of noncannibal members of broods spawned in the lake. Cannibals prob- ably made a less significant contribu- tion to the harvest during the second study period than during the first. In the years of fair to good bluegill fishing during the first period, and in the one year of fair bluegill fishing in the second period (1950), the bluegill har\ests were made up largely of fish from broods produced in the lake after the stockings. In 1947 and 1948, the poor bluegill han'ests were made up principally of fi.sh of the 1946 stocking. Growth of Original Bass Tlie largemouth bass with which Lake Glendale was stocked in April, 1940, grew rapidly. Those from which scales were obtained were found to have grown much more rapidly than is usual for bass in older populations. Bass of 10-14 inches (the sizes of the bass used in stocking Lake Glendale in 1940) ordinarily increase their weights at the rate of a quarter pound to a half pound a year. Six bass of the 1940 slock caught in hoop nets in March, 1943, had put on weight at the rate of 1 to 2 pounds per year. At that time, they ranged from 18.4 to 21 inches in length and from 3.7 to 6.4 pounds in weight. One of the 1940 original bass taken in the 1946 population census weighed 8 pounds, 9 ounces, and meas- ured 23.4 inches. This is the largest bass that has been recorded from Lake Glendale. The bass with which the lake was stocked in 1946 grew less rapidly than those of the 1940 stocking but more rapidly than bass in most old popula- tions. Shifts in the modes of the length- frequency distributions for bass caught Table 20.—Numbers of marked (fin-clipped) largemouth boss of three length categories used in stocking Lake Glendole in the fall of 1946, ond size distributions of port of catch of marked fish taken by sport fishermen over the next 4 years. Some marked fish were not meosured ond some fish with clipped fins were not recorded as having been marked. This table includes only fish that were recorded os marked. 140 Illinois Natural History Survey Bulletin Vol. 29, Art. 2 by sportsmen in 1948-1950 (Table 20) indicate that fin-clipped bass placed in the lake at lengths of 3-11 inches were caught at lengths of 10-16 inches in 1948, 11-17 inches in 1949, and 13..5-18 inches in 1950. The number of bass used in the 1940 stocking (70 individuals) was too small to ha\'e much direct influence on the fishing in 1942-1946. The number of bass used in the 1946 stocking (2,248 individuals ) was large enough and the giowth of these fish was rapid enough to contribute significantly to the catch, especially in 1948 and 1949. Growth of Bass in New Broods While most bass hatched at Lake Glendale in 1940 grew C(uite slowly, scale examinations showed that some individuals—the so-called cannibals — from the 1940 brood and a smaller number from the 1941 brood grew rap- idly. By the spring of 1942, after only two growing seasons, the cannibals had reached lengths of 10-15.5 inches ( Tables 14 and 21 ) . By the spring of 1943, the cannibals measured 11..5-18 inches, while most of their slow- growing brood mates measured onlv 7- 10 inches. Scales examined from large bass caught in hoop nets in March, 1942, indicate that the bass of 18. .5-19 inches caught by anglers in 1942 (Table 14) were fast-growing individuals of the original stock, rather than cannibals. At the time of the 1946 population census, 21 cannibals from the 1940 brood measured 17.8-21.6 inches, 10 cannibals from the 1941 brood meas- ured 17.1-21.0 inches, and 1 cannibal from the 1943 brood measured 17.1 inches. Measurements of these fish are included in Table 22. The large bass included in this table as members of die 1939 brood were either individuals from the unplanned stocking of 1941 or were members of the 1940 brood that had formed false annuli. Large bass included as members of the 1938 brood might have come from either the 1940 or the 1941 introductions. Cannibals measuring 10-14 inches in length made up part of the bass har\'est in 1948 ( curve B and part of curve C in Fig. 7), but most of the harvest in that year was deri\'ed from the fast- growing original stock of 1946 (curve A and the greater part of curve C). Undoubtedly, some cannibals were caught in 1949 and 1950, but the ex- tent of their contribution to the har\est in those years cannot be determined. As a result of the poor growth of most of the bass hatched in Lake Glen- dale in 1940-1946 and the small num- ber of cannibals in broods other than those of 1940 and 1941, bass of 11-17 inches were scarce in 1944—1946. This scarcity is shown by the sizes of bass caught by test fishennen (Table 13) and by other fishermen (Table 14), and by the sizes of bass in hoop-net samples ( Table 21 ) . Of the 6,861 bass in the 1946 popu- lation census (Table 26), 6,784 meas- ured 3-12 inches, 3 measured 12.5-17 inches, and 74 measured 17.5-23.5 inches; of the fish of 12 inches and smaller, not more than 20 are estimated to have been longer than 11 inches. Evidence from scale examination is that an exceptionally large brood of bass was produced in Lake Glendale in the first spawning season after each stocking, tliat is, in 1940 and 1947, that the lake became overstocked by these first bass broods, and that the over- stocked condition was maintained through natural reproduction in sub- sequent years. The major part of each brood was at least slightly stunted. Ap- parently, most of the slow-growing members of the 1940 and 1941 broods died in the lake, or were caught by fishennen, without reaching lengths much abo\e 10 inches. Fishing in the years 1943-1946 and 1949-1950 would certainly have been better if bass re- production had been less successful. The slow growth of most individuals of the 1940, 1941, and 1942 broods is suggested by the absence of significant shifts in modes in the length-frequency July, 1966 Hansen: Stocking and Sport Fishjng at Lake Glendale 141 distributions of bass under 10 inches collected in hoop nets in March, 1943- 1945 (Table 21) and also by scale ex- aminations. In March, 1944, hoop-net samples, the noncannibal bass of the 1940 brood (represented by 11 fish) averaged 10.2 inches after four grow- ing seasons; those of the 1941 brood (6 fish) averaged 9.2 inches after three growing seasons; and those of the 1942 brood (7 fish) averaged 8.1 inches after two growing seasons (these data not in tables ) . Approximately the same degree of stunting was obsen'ed in broods spawned after the 1946 stocking. Length data and scale samples col- lected from noncannibal bass at the Table 21.— Size distribution of lorgemouth bass tal