.... ...x .mw ...... my um Cm an; ash. A: ..an .3 ,v. 3 fi em a k G A M E .. o9”... .. 3... VJ“... L a ...... a... . . .m L ......H m7”. ..N w”... ..b o It . 0, mm C u c .....M“ .V 1 .‘VO nfi”. 5" 9‘. w r . 3. ...... 1m ”-8 n 11.... . ... d Md...“ u WWW . r g w..- 2 . . D A m... 5 O J hm: t 1 «MI T “U G! \ .u... 3 ...? m 5 3 ¢ . i.‘ no u .Htt I‘M: a. W“ “(V “$5 0 N ,. .. ..u. ... Alyv "Von... h... A a u T. M” ..M G a) .7. w an. a“ .... Hun .u I .IJ c an flu in & {nu H a .sa‘ .‘1. a! I c l- ?9 4“ n» t at... a "is K)! V0 7%.. an. 1M0». 6 .. T. a s. an t» . a. i w I at. ‘ .H .L. g... r _:,:___:__E_,23212::22:25; 'i'tifiéilii This is to certify that the thesis entitled A Laboratory Study of Natural Food Conversion And Growth Rates of JJargemoutfll and Smallmouth Black Bass presented by Wells E . Williams has been accepted towards fulfillment of the requirements for _M_-S_-_degree mm <31: Wildlife a Z; ,2 242%, Major professor 20, 19514 ph R: Date h' 0-169 A LABORATORY STUDY OF NATURAL FOOD CONVERSION AND GROWTH RATES OF LARGEhOUTH AND SIJZAIJMOUTH BLACK BASS By Wells Eldon Willians A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1951» THESIS ACKNOWLEDGMENTS The author wishes to express his sincere thanks to Dr. Peter I. Tack, under whose able supervision this investigation was undertaken and to whom the results are herewith dedicated. He is also greatly indebted to Dr. Robert C. Ball for his valuable suggestions and guidance. Particular thanks are given to Robert B. Chapoton, a graduate as— sistant who aided in making collections, and to Jack Hernly of Lansing, Kichigan, without whose kindly help this paper might not have been writ- ten. 331296 TABLE OF CONTLNTS Acknowledgnents . . . . . List of Tables and Figures . I. Introduction . . . . II. Lethodology and Procedures A. B. C. D. E. III. A. B. C. D. E. "1 Po Previous Studies . Aquaria . . . . Weight and Length Deterninations Forage Fish and Feeding . Treatment of Diseased Fish . Statistical hethods Food Conversion . Weight Gains . . Growth Rates . . Length Gains . . Effect of Size of Prey on Feeding Presentation and Analssis of Data Effect of Diseases on Growth and Conversion IV. Summary . . . . . Selected References . . . {\J 10 10 ll l2 15 15 18 is 20 22 23 Figure I. Table Table Table Table Table Table l. 2. \0 LIST or TABLES AND nevus Photograph showing aquariur set-up used in feeding Stud; 0 o o o o o o o o o o o o o o o 0 Weight data and food conversion for 21 snalluouth bass . Weight data and feed conversion for five largenouth bass 0 o o o o o o o o o o o o o o o o Sunmary of statistics for comparison of mean weight gains between largenouth and snallnouth bass . . . . Comparison of feeding rates to instantaneous growth rates of largenouth and snallnouth bass . . . . . Length data by species for 26 bass studied . . . . Sunnary of statistics for comparison of mean weight gains for diseased and disease-free smallnouth bass. . 13 11'; 16 l7 l9 A INTRODUCTION It has been previously demonstrated that growth rate is an impor- tant factor in the life history studies of fishes (tester, 1932), and that ultimate fish yields depend upon the availability of food and the efficiency of its transformation into the various fish body tissues. An experimental method of providing maximum yields consists of provid- ing maximum food availability by the use of shortened food chains, which eventually leads to consideration of the efficiency of food conversion (Swingle, l9h9). Food conversion factors are obtained by dividing the« weight of food consumed by the amount of gain in body weight, and prove useful in evaluating yields, since they establish a relationship between the amount of food ingested and the increase in body weight of individé ual fish fed. In order to add in some small measure to the existing knowledge concerning feed conversion and fish growth, the present study was de- signed to test the efficiency of conversion and growth rates of 21 small- mouth bass, Micropterus dolomieu dolomieu, and five largemouth bass, gigropterus salmoides salmoides, fed twice daily on known weights of forage fishes in the laboratory. Previous Studies The current literature contains few comprehensive reports concern- ing feed conversion studies, although some workers have accomplished notable work in this respect. Thompson (1941) found an average conver- sion factor of 2.5 for twenty largemouth bass ranging in size from fin- gerlings to one pound in weight, fed live minnows at an average tempera- ture of 70 degrees fahrenheit in individual aquaria. For simplicity, conversion values for bass of all sizes were adjusted to those of ten- inch bass. He stated that maximum food conversions were obtained by feeding from 3.5 to A.O percent of the initial body weight daily, and that food was utilized less efficiently when larger amounts were fed. This suggests that greatest efficiency of food conversion may be attained at submaximum levels of feeding. Earlier, Kingsbury (193h) estimated that about nine pounds of food were required to produce one pound of bass at an average temperature of 70 degrees fahrenheit, using a variety of artificial foods. In a later study, Kingsbury and Royce (1935) re- ported that young bass fingerlings held in hatching troughs required about fifteen percent of their body weight daily in order to convert food to flesh, varying with temperature and the type of diet. Prather (1951), by selecting annually from fast-growing individuals fog brood stock over a six~year period, was able to produce fast-growing yearling bass that converted an average of 2.06 pounds of live forage fishes to one pound of body weight. The bass were fed twice weekly in outdoor ce - ment aquaria twelve feet in diameter and two feet in depth. During the first year of the study, fish were fed from .5 to 9.5 percent of their initial body weight daily, but since it was found that those individuals fed at the highest rate were unable to consume all the food given them, he fed five percent of initial body weight daily in later experiments. An average conversion factor of about four was found by Lagler and Kruse (1953) in an experiment with four largemouth bass and three small- mouth bass held in individual aquaria placed out-of-doors and supplied with running water from a nearby lake. The bass were given an average two-day diet of three species of live forage fish for a period of about four weeks. METHODOLOGY AND PROCEDURES The experimental work was conducted in the fisheries laboratory of the Fisheries and Wildlife Department at Michigan State College in East Lansing, Michigan. The feeding program was carried on over a period of fourteen weeks, beginning on December 1, 1953 and ending March 9, 195A. For the study, a total of 26 fish were used, 21 smallmouth bass and five largemouth bass collected by the use of an electric shocking apparatus from the Ned Cedar and Looking Glass Rivers near East Lansing. No at— tempt was made to collect any particular size or age class for the ex- periment. Captured bass were placed in individual glass-sided aquaria in the laboratory, and were fed approximately all the live food they would con— sume for one week previous to the initial weight and length determinations. Weights of forage species fed during this adjustment period were not re- corded. Aquaria Four of the aquaria used had a capacity of about fifty gallons, and were divided by glass spacers into four approximately equal compart- ments of about 12% gallons (see Fig. I). Four smaller aquaria were di- vided into two compartments of about It gallons each. The largest bass in the sample was placed in a large museumptype display aquarium with a capacity of slightly over 100 gallons. Spacers used were of double-strength glass plates cut about one- quarter-inch less than the inside width of the aquarium and high enough l I Y! I 1.35.:mgh .mpspm mafieoom esp ma non: autumn saddened MCfizonm :anMOponm H mmDUHm 9 so that approximately two inches of the plate extended above the water level. Installation of spacers was accomplished by placing short lengths of 1/8-inch rubber tubing over the edges and forcing them into position. Some space was left between lengths of tubing to allow oxygen diffusion to all compartments of the aquarium (Fig. I). By the use of these glass spacers, cannibalism was prevented, no marking of fish was necessary, and bass could be fed and observed individually. Double-strength glass plates were used to cover all aquaria. Aquaria were filled to capacity with tap water (assumed to be chlor- inated) and aerated for 24 hours before bass were introduced. One aera- tor was placed in an end compartment of each aquarium. It was assumed that by using tap water, little if any plankton would be available for food. Consequently, no plankton measurements were deemed necessary. water was added only when needed to keep aquaria filled to capacity, and once each week, excrement and accumulated materials were removed by siphoning with a short length of hose to prevent putrefaction. weight and Length Determinations Individual bass were weighed and measured at the beginning of the experiment, three times during its course, and again at its conclusion. Forage species were weighed in water to the nearest .1 gram, and excess water was allowed to drain off before weighing. Bass were weighed in the same manner as the forage species, but were first anesthetized by immersing in a one percent solution (by weight) of ethyl ether until loss of equilibrium was apparent. The length of time fish were allowed to remain in the solution varied with the size of the fish, although g;enerally, about thirty seconds was found sufficient to make them un- lO stable enough to handle easily. Length measurements were made to the nearest millimeter by the use of a home-made fish measuring board. Forage Fish and Feeding Bass were fed live forage fishes twice daily, at about 7:30 A.M. and 5:30 P.M. Dead forage fish and those not consumed by the subsequent feeding time were removed, weighed and subtracted from the record. Temperature in degrees.f;hrenheit was recorded during each feeding period from a chemical thermometer placed in each aquarium. Cement tanks in the laboratory were used as holding tanks for for- age species. Included among forage species were Eucalia inconstans, Pimephales promelas, Lepgmis machrochirus, Notropis heterolepis, Notropis atherinoides, Chrosomus eos, Notemigonus crysoleucas auratus and Notropis cornutus. Treatment of Diseased Fish During the course of the study, it became necessary to treat two of the smallmouth bass for fin rot and three for fungus. Individuals infected with fin rot, apparently a bacterial infection for which the causative organism has not yet been isolated in pure culture (Davis,l953), were treated by immersing in a three percent NaCl solution for about fifteen minutes; the treatment was administered daily for one week. 180th of the fish treated for the disease showed marked improvement af- ter five of the salt treatments, and effected fins showed new growth in about 10 days. For treatment of the fungus (Saprolegnia) a 1:10,000 solution of Imalachite green oxalate was made by diluting .38 grams of malachite 11 green lustrous crystal into one gallon of water, and infected fish were immersed in the solution for about two minutes. After three treatments spaced two days apart, the effected individuals showed improvement, and in two weeks the fungus had completely disappeared. Statistical Methods Statistical procedures used in calculating differences in mean weight gains were those presented by Snedecor (1950), and all computa- tions were made on a computing machine. Analyses of data by statistical methods were made only on order to simplify interpretation of data. l2 PRESENTATION AND ANALYSIS OF DATA Food Conversion water temperature during the experiment ranged from 67 to 77 degrees fahrenheit, with an average temperature of 70.3 degrees for the lA-week period. The conversion factor for both bass species was found to be 5.6, with that for smallmouth bass 5.63 (Table 1) and that for the largemouth bass 3.81 (Table 2). The average value for the entire sample closely coincides with the ratio of five to one as used by several German work— ers and suggested by Richardson (1921) for fish living primarily on ani- mal food. Individual bass varied considerably in the ability to convert food to flesh, as was indicated by conversions ranging from 2.1L to 15.33 (Tables 1 and 2). The application of the regression formula (Snedecor, 1950) to ini- tial weights and food conversion rates of 16 smallmouth bass studied (those treated for diseases were ignored in the calculation) supports the xtwthat larger fish utilize more food in maintaining the body and. thus are less able to convert food to flesh. Although the "t" test is not significant for the data presented, the sample estimate cannot be ignored, since there is evidence to support some relation between the initial body weight and feed conversion. Conversion rates, therefore, can be partially predictable, each gram increase in initial bod; weight (xxrresponding to an increase of .0025 in the food conversion rate of snaullmouth bass in the sample. The use of the regression formula nay leaxi to predictions of conversions fer larger populations, and may be TABLE 1 13 WEIGHT DATA AND FOOD CONVERSION FOR 21 SMALLMOUTH BASS Initial Wt. Final Wt. Total Wt. Amount of food Conversion (grams) (grams) gain given (grams) factor (grams) 1, 21,. 2O 52 2.60 5 25 20 56 2.80 8 22 1A 51 3.64 13 33 2O 82 h.lO 22 33 11 89 8.09* 22 57 35 107 b.03 2A 31 7 31 A.A3 26 33 7 5 7.86 31 L6 15 79 5.27 34 A9 15 98 6.53 39 A5 6 92 15.33* 39 66 27 120 A.hh A0 55 15 98 6.53 55 98 A3 112 2.60 {16 81+ 38 151. 5 . 5o 60 113 53 198 3-7A 87 117 30 237 7.90% 9A 121 27 252 9.33* 111 11m 33 121 3.67 112 177 65 309 A, 75 119 1A0 21 283 13.48% Average food conversion factor: 5.63 * Denotes conversion factors for fish treated for diseases. 1A TABLE 2 WEIGHT DATA AND FOOD CONVERSION FOR FIVE LARGEMOUTH BASS Initial Wt. Terminal Wt. Total Wt. Amount of food Conversion (grams) (grams) gain (Cm) given (grams) factor [161; 526 62 I109 6. 59 27 38 11 63 5.73 22 72 50 107 2.1A 20 75 55 129 2.34 19 ' an 25 .57 2.28 Average feed conversion factor: 3.81 15 valuable in studies aimed at determining amounts of food utiliZed by fish for maintaining the body. Undoubtedly this sample was too small to yield a valid regression coefficient. However, the method may prove to be of considerable value when large samples are involved. The average food consumption for all bass studied was A.3 percent of the initial body weight daily. This value is only slightly higher than the optimum rate of feeding suggested by Thompson (19A1). lesults of the present study indicated that most efficient conversions were ob- tained by feeding from five to about thirteen percent of the initial weight daily (Table A). Weight Gains In comparisons of weight gains between the two bass species, it was evident that significant weight gains occurred (Table 3), with the largemouth bass showing greater weight gains than smallmouth bass. To— tal weight gains for individual bass ranged from seven to 62 grams (Ta- bles l and 2). The largest weight gain for one individual, as compared to initial body weight, was shown by the smallest bass in the sample. This fish gained five times its starting weight during the IA-week peri- od. Growth Rates Instantaneous rates, expressed as the natural or Naperian logarithms of the simple quotients obtained by dividing the terminal or final weights by the starting or initial weights of bass studied, were selected to .represent relative growth rates (in weight) of fish in the sample. The Icelationship is expressed by the formula 1::Loge Yt/Yo where i is the TABLE 3 SUMLARY OF ST TISTICS FOR COLPARISON OF EEAN WEIGHT GAINS BETWEEN LARGEEOUTH AND SMALLMOUTH BASS Species Number Degrees Mean Wt. gain Sum of squares observed freedom (grams) Smbl 21 20 2A.h 595.36 lmb2 5 A t0.6 16b8.36 Sum :- 21. Difference:16.2 Sum 222143.72 Pooled variance :— 22A3.72/2£+ : 93.1.8 Standard deviation from meany .h8 2l _—_ [”81 21 5 t = 16.2/A.8l = 3.37% l Denotes smallmouth bass. 2 Denotes largemouth bass. .mUSom one mcwpso mommomwe pom woodman mmmn mo mopwp :p3oam mdomcdpcmmeH mopedma * l7 .mmdn SpSOEHHdEm mopocoa “amen spSOEmMpwH mopocmo N H *00HOO. mH. 4.N mm 04H mHH = 50400. om. m.N mm 55H NHH = monoo. um. N.m 4m 44H HHH = *mmmoo. 0N. b.N mm HNH 40 = *NOmoo. mm. m.N mm bHH hm : ommoo. mm. 4.m ma mHH 00 : 4H400. Hm. m.N mm 4m 0m : omeO. mu. H.N mm mm mm : mmmoo. mm. m.N mm mm 04 : *04HOO. mH. 4.N 00 m4 on : NMmoO. on. 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