THE ECOLOGY. AGE AND GROW?H RATE OF THE CENTRAL JGHNN’Y DARTER, emaogrgmA. 131% ‘W aRAHNESQUE), AUGUSTA CREEK, met-emu Thesis far #116 Deg?» 9? Ph. D. MECHIGAN STAKE URWERSlTY Edwarfi Phelps Spears 1958 This is to certifg that the thesis entitled The ecology, age and growth rate of the central Johnny Darter flheostoma nigrum nigrum "Rafinesque" Augusta Creek, Michigan. presented by Edward P. Speare has been accepted towards fulfillment of the requirements for M degree in M AZLHDW Major professor Date November 11;, 1958. 0-169 TJ" Way‘s. f' - I “9 HULL» ‘y."\'\v-‘- “Vru-fl. (Rx? } THE ECOLOGY, AGE AND GROWTH RATE OF THE CENTRAL JOHNNY DARTER, ETHEOSTOMA.NIGRUM NIGRUN (RAFINESQUE), AUGUSTA CREEK. MICHIGnN by EDWARD PHELPS spm AN ABSTRACT Submitted to the School for Advanced Graduate Studies of Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSLPHY Department of Zoology 1958 Approved é :Zg. 7Q 39min; co restatioze it. maps were set 34:3. Recoris 797831 that in P. 4 e o r 7" .ln;‘“°)' év/U . 3‘ .4 ‘ 5J2 PumllCflLl' h,- i ‘, b-engCQl -rE t iefise E11: 1/ {There 1 ‘ul‘eliv e, C V. i‘ ‘1 age‘groxp \‘R “tn . q l'x V llei H the ‘8‘} \ ”any. AN ABSTRACT Seining collections were made during 1957 and 1958 at ten stations in Augusta Creek, Michigan. Three ecological groups were set up by combining stations with similar hab- itats. Records of the numbers and kinds of associated fish reveal that in E-I (pools) the Johnny darter constituted 60% of the fish pOpulation; E-II (riffles), 53%; and E-III (rapids), 20%. The next most abundant fish in the stream were Rhinichthys and gemotilus. certain ecological factors of the Johnny darter were studied, including the associated fish, aquatic plants, aquatic insects, and algae. Monthly tests were also con- ducted for temperature, alkalinity, 9H. and oxygen concen- trations at each station during 1957. "Envirographs" of the ecological factors show that the Johnny darter has an ecological preference in the Augusta Creek for quiet areas with dense aduatic plants. Qérhere is evidence to suggest homogeneity of the darter papulation for the stream and differences in sex ratios for all age-groups are not significant. First year darter growth is equal for both sexes. after which the males ex- ceed the females by32.5 mm. The coefficient of condition is slightly higher for young-of-the-year than for older fish but is equal for both sexes. Values for the length-weight relationship are also given. :357m 1355 3‘ .c‘ci difference he. The “'91“ he oldest. fish Charles 39" Ml”; full {Halal {asses of eggs. um “uni mm: 8.101)! 60 eggs nut 65% of tm "femurs 1r. Argon“ is from I 11; necks 1r. tr. ”filed that use ilmltgnla was Fall age-group prOportions showed 8% for the 1956 year class, 43% for 1957, and 49% for 1958. Growth rates of 1957 and 1958 young-of-the-year were compared and no signif- icant difference was found despite an earlier 1958 spawning date. The mean survival rate was determined as 2.0 years. The oldest fish taken was a male. Age-group IV. 58.2 mm. Ovaries develoP slowly from June through September and reach full maturity by January. Ovary counts showed three classes of eggs; ripe, deveIOped, and immature, all in about equal numbers. The three-year-old females lay approx- imately 60 eggs per OVary and may spawn twice in one season. About 65% of the one-year-old males and 86% of the females were mature in their first Spawning season. The spawning period is from May 1 to June 1, but may vary by as much as two weeks in the spring. Field studies of egg-batches re- vealed that about 18% of the eggs laid die before hatching. Saprolegnia was commonly found on the unviable eggs.) THE; 30.22:: 304.23.“! 1 (an; THE ECOLOGY, AGE AND GROWTH RATE OF THE CENTRAL JOHNNY DARTER. ETHEOSTOMA NIGRUM NIGRUN (RAFINESOUE). AUGUSTA CREEK, MICHIGAN by EDWARD PHELPS SPEARE A THESIS Submitted to the School for advanced Graduate Studies of Michigan state University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of zoology 1958 Approved i ;fi :7 .W — The author ”mm assist.‘ PW 1- Tacit, ( W members or Ml, but cape h «8“! '0 R081 We“. and 1 I summing the ACKNOWLEDGMENTS The author gratefully acknowledges the scientific and personal assistance given him throughout this study by Dr. Peter I. rack. committee chairman. Sincere We are due many members of the lichigan State University teaching Staff, but especially to Dr. Clarence Schloemer who guided my field worn at the Kellogg Biological Station, to Dr. Eugene I. Roelofs for his help with respect to the scale critique, and to Dr. George A. Petrides for his suggestions concerning the population studies and random sampling. For all photographs of the stream. equipment, and Prepared slides, the author is indebted to Mr. Roger Tharp 0‘ Olivet college. My particular thanks go to my wife. Patricia. for her constant encouragement and literary criticism without Ihicll this study could not have been finished. ii TABLE OF CONTENTS Acknowledgments . . . . . . . . . . . list of tables list of figures . INTRODUC T ION A. Early darter studies . . . . B. Recent darter studies . . . . C. Purpose of this paper . . . . aUC-UST&CREEK........... A. B. C. D. METHODS A. B. CENTRAL B. C. D. V‘ A. Stream description . Limnological factors 1. 2. Oxygen . . . 3. 4. 5. Stations e e e e e Ecological groups . Alkalinity . . PH 0 e e e e e Special tests . AND HATER IALS . O O O C O O 0 Collecting techniques 1. 2. Methods and materials 1. 2. 3. 4. 5. 6. JOIImNY DARTER O O O O O O A- General description . . . 1. 2. 5. Synonomy . . . GeographiCal distribution Darter habitat . . . . . Micro-habitat . . . . . . Johnny darters Associated fish Weight .... . . . Length . . . . . Preserving . . . . es Sex determination Validation of techniqu Scale sampling . . . Etheostomidae . . . General description Taxonomy..... . . . iii Page ii vi P kn» (DDD¢HOODQCDOHb o» topaw C0 01 OLNIUODNCOODNWDOD OJwWDGHw-Q2LF ‘ ‘e "o 1‘- “ v 13.33.10 MTu (J .1.- dme mi 1.;6 D. AGE AND D. E. F. REPRODUCTION................. A. B. C. TABLE OF CONTENTS. continued RATE OF GROWTH . . . . . . . . . . . . . Scale method . . . . . . . l. Perch family . . . . 2. Scale taxonomy . . . 5. annulus formation . 4. circulus analysis . A36 and rate of growth . l. Pepulation study . . 2. Geographical influenc age-groups . . 3. Seasonal growth . . . . . . . . . 6 on mean leng t 4. Homogeneity of ecologiCal groups and Stations e e e 'e e e e e e e 5. Post-hatched growth 1957 v . l958 Survival rates . . . . . . . . l. TheoretiCal natality . . 2. Ecological natality . . 3. Mean survival rate . . . Papulation structures . . . . l. Preportion of age-groups ing season . . . . s t end of n spring 2. Fraportion of age-group fall seasons . . 3. Sex ratios . . . . . . coefficient of condition . . Length-weight relationship . eeeep-I-omceee Secondary sexual characteristics 1. Spawning coloration ,... 2e Genitalia e e e e e Gonad develOpment . . . . 1. Seasonal changes . . 2- Gonad regeneration . 5. Fecundity . . . . . Spawning . . . . . . l. Field studies . . . 2. Spawning dates . . . . 5. Number of eggs Spawned 4e E88 Viability e e e e 5. Number left unspawned 6. Spawning act of laborat Hatching . . . . . . . . . . 1. Embryonic develOpment 2e P08t‘hatChed fry e e .00.... .00....00... Seeeeeeeeeeeee p... DeeeeeeeeeeOOe (fl e00m.e0eee n) 0 0 0 (.0 0 0 . 0 0 0 0 C 0 0 0 0 FY e oOeOeeceeeeeeoe eee 0.. eee iv meooeeee eeees eschew mm sm>Hm mama * 10 5H mm am am ma ma ma woma.mm.aaon m.e~ m.ma o.ma ma em «a on .mmmd.om .saom mm mm em mm mm -- om swam .m .ms< mm on an em ma ma -- swam .om mass ma em . nm am am pa ma snag .H has» *Xeeao hexawo mexaao hexaac .aoczb .aoczh a .mam even spasmsd oaapag soaamnm mam Baden o>on< mmmflm monuem Hexadc II .lcxsq xoeheseH xhounoeam 1"‘1. ‘.l mama 924 NmQH .216Hmowfl .xmmmo sBmDODd OZHZHOfiQ< mmxdd mam madmOHBzmo mammdQQ.ZH ZM>HO mflflohdmmmfima mmkd; .%.H mqmde ¢.mH|m.© «.aa ¢.&a N.HH O.m O.® 0.0 N.b O.m ¢.N« n.aa n.ma m.aa NO «mmlnod ¢Om Had bra «MN mam flow HON nod and SAN nod mom .O.E o.m-o.a 0.5 o.m n.m 0.5 m.a m.a m.s o.o o.m m.a 3.5 w.a ma .msoa emamm .oo: £52 .900 .amom .m3. :3. 22:. he: 3:3 33: .nom .93.. mama 'lel I! I .- I. hnmd .Z£¢HmoH: .xMflMO,¢HmD¢D< 20 flat: mOZHmtflm A1 w.d mamas - y l“ Flu 1d C. STATIONS. The stream Was divided into ten stations nearly equally spaced over the 14.5 mile course. Each station was identified with a bridge-crossing and extended uP or down stream approximately 100 yards. The upper limit was determined by a sharp change in the stream bottom. depth, or other natural occurrence. Thus each station was limited to a particular habitat type. (Figs. 1.1-12) Station 1. Origin: upper end of stream; NH i Sec. 23. T. l N. R. 9 w, Barry 00.; westward from bridge on Litts Rd. 150 yds. to margin of Pitchfork Swamp; rate slow. 1/3 ft. per sec.; width 12'; depth 8"; bottom sandy; §2arganium. gtheostoma, and lendiggedidae all very abundant . Station 2. Origin: bridge crossing on Co. Road 400; NE ‘3‘: Sec. 26. T. 1 N, R. 9 W, Barry 00.; northward 200 yds.; "“3 slow, fi'/sec.; width 20'; depth 10"; bottom sandy; W abundant among Typha. Potamogeton. and Spargan - fl; insects Notonecta and 51935 common; Spirogyra in small .ddies. Station 3. Origin; 400 yds. below bridge on nann Road; S“ % Sec. 26. T. 1 N. R. 9 11. Barry 00.; southward 100 yds. thrOugh woodlot; rapids; rate l'/sec.; width 12'; depth 5"; bottom gravelly; Poecilichthys abundant; Nasturtium and ILLS at the margins only; mold and algae on submerged rocks . Vanni" .....VIWta , l..\w.A v...” M M. ‘ Q .11... I. 1.... Man .. . . A. all I" flu A i mi. 11; c. a..._1.. 57/... x i .. . Iqi if-..” ‘A file 1.2 Station 1 Fig. 1.1 Head waters Fig. 1.4 Station 3 Fig. Station _2 1.3 Fig. 14 making bottom dark in color. Station 4. Origin; bridge on Sheffield Road; SE i Sec. 34. T. 1 n. a. 9 w. Barry 00.; southward 150 yds. to Aorn's fence line; rapids; rate 1'/sec.; width 15', (19131.11 7"; bottom gravelly; Semotilus. Rhinichthys, and Wpredominant; Typha and Scripus at margins only. Station 5. Origin: bridge on Lepper Road. NW it See. 5. ‘1'. l s, R. 9 VI. Kalamazoo co.; westward 200 yds.; some x'1f‘fles; rate 1.3'/sec.; width 21'; depth 8"; bottom Pfibbly to gravelly; Poecilichthys abundant among Johnny darters; .tufts of gotamogeton natans within stream proper; silt. greatly reduced. Station 6., Origin; bridge on Lepper Road. NW % Sec. 10. T' 1 S. R. 9 Vi, Kalamazoo Co.; northwest 100 yds.; rapids; ”'00 2'/sec.; width 25'; depth 7"; bottom gravelly; ....EthGOstom very few as are aquatic plants. mborhynchus Pmdominates . Station 7. Origin; bridge on 0 Ave. E... SW i— Sec. 10. T- 1 S. R. 9 u, Kalamazoo Co.; westward 200 yds.; riffles; rate 2'/sec.; width 18'; depth 13"; bottom gravelly to P9331113]; gtheostoma and ghinichthys abundant. Scattered W- Fig. 1.? Station 6 Fig. 1.8 ‘Station 7 16 Station 8. Origin: bridge on Route 89 southward 25 yds. and northward 80 yds. from Lookout Point Bridge in Kellogg Forest Tract; NE % Sec. 21. T. 1 S. R. 9 w; Kalamazoo 00.; bottom sandy, rate moderate, 1'/sec.; width 18'; depth 25". Many species of associated fish. hum- Station 9. Origin; bridge on EF Ave. 13.. sw i Sec. 27, ; T. 1 S, R. 9 w, Kalamazoo 00.; northward 100 yards; strong 3 twipids; rate 2'/sec.; width 50'; depth 11"; bottom gravelly; [ Qatostomus in deep holes, Qottus in silt margins. Etheostoma in Specialized areas only. Station 10. Origin; dam site below augusta, SW 2 Sec. 54. T. 1 S. R. 9 W. Kalamazoo 00.; southward 80 yds. to Junction with Kalamazoo River by-pass; rate variable de- Pending upon position of dam gates; no aquatic plants; alga.gladqphora in swifter parts. . l4 . ‘r 1 I. I1.“- r (I K outlet 18 D. §00LOGICAng§Qg§§, By correlating the data on stream characteristics given in Table 1.7, the ten stations were then combined into three ecological groups identified as E-I. E-II. and E-III. consideration was given to the following factors as they collectively constituted a.part- icular ecologiCal setting in which the Johnny darter found its niche; rate of flow, bottom type, silt deposition, aquatic plant abundance. species of associated fish, algae, and aquatic insects. Separate species lists are given under Ecological Analysis. (See chapter on Ecological Analysis.) E-l Aigtations li 2L 8) This ecological group charact- eristically has a slow rate of flow (%'/sec.), a sandy- silt bottom, and is covered with snail shells of Planorbis, Amnicola, and the tiny white broken parts of the clam Sphaerium. Fine soft silt piles up at the margins shift- ing frequently as the depth of water and consequently the rate of flow varies. Sparganium,'§agittaria. and Anacha- 533 form dense mats at the center of the stream in the upper portions and at the silt-laden sides of the lower section. The width averages 12' and the depth 6". In September filamentous algae_§pirogyra and gladOphora form long "algal rapes" and cover the larger stones in small riffled areas. TABLE 1.7 ECOLOGICAL COMPARISON OF 10 STATIONS ON AUGUSTA CREEK 195.7 1.9 uommoo} . P—fi—t ‘puniif‘ a I 3 ' uommoo C0 '5 'ptmqv g uommoo to 2.3 'ptmqv Q In uommoa ' 3'3 : 4‘" 'punqy f a 3 t? 3(an 0’ > ° 9 '1' J 111811 I m Pitts $5 :3 to Kpues g erqs I 8 [nuns ; Sptdsu‘. 0 eqemepon » z 33 acts I etiqen £31003 3 E Ktqqad . ‘9 Kptres 1 5 e'inpon ‘ re «4 3: 0mm mortsus '3 . eqeaepofl 3‘ 9 dead sucttvts X I I I x I I I I I I I I I x I I I I I I x x I x I I I I I ' x x I x ' x x I I x I I x x K I I x I I K x I x I I x I x x x I x I I I I I I I I I :4 I I x x I I K x x N N I I I I I x x I I I ' ' X >4 x x ' l X K ' K N I I 10 20 This represents the optimum of conditions for repro- duction. protection, and food sources. this latter being supplied first in the form of algae for the fry (goelo- sphaerium. glosterium, Scenedesmus) and secondly as insect larvae for the adults (midges). Their natural fish preda- tors. the large and small mouth bass. are very rare. From this ecological setting, approximately 50% 0f the 2000 darters used in this study were taken. gtggLi(§tations 5. 7. 10.) This group is characterized by their scattered deeper holes. These render an abundance of associated fish but because of the shallowness of the rest of the station and its resultant swifter current and rocky bottom, the Johnny darter is found in isolated areas only. Here the bottom is pebbly to sandy. Depth is 8" and the width averages 15'. Larger rocks break the surface and form backeddies. Silt is reduced at the edges and the aquatic plants are not abundant. consisting mostly of £93- amogeton and Nasturtium in isolated areas. Algae such as ggadqphora and molds are profuse on the larger rocks. The aquatic insects are not abundant as in E-I. Present also are Planorbis, amnicola, and QEEEEEEE but in reduced num- bars. The western black-nosed dace Rhinichthys and Semoti- lus are the most abundant associated fishes. Often lumber, iron wire, and hardware debris litter the blackish, firm pebbly, unchanging bottom. Fig. 1.13 Ecological Group I Fig. 1.14 Ecological Group II '0 22 The lack of aquatic plants is reflected in the reduced kinds and numbers of the "desired" aquatic insects such as Chironomids and Ostracods. There are few breeding areas supplied with stones large enough for satisfactory egg- laying.1 The gravelly. pebbly bottom is less effective in providing a natural cover than is a speckled sandy bottom. Here the Johnny darter constituted only 33% of the catch taken at these stations. ‘§;;;;f (Stations 3. 4L_5; 9) This ecological group is typified by its rapids and broken surface water. The bottom is stony and gravelly. A.b1ackish mold and blue- green algae grow on most of the stones. The sand has washed away and there is little silt at the sides of the stream. It averages 5" in depth and 24' in width. This group is devoid of aquatic plants in the stream proper. Nasturtium; Pontederia, and Decodon are found at the sides in the quieter regions. Small patches of Potamogeton exist at station 9. There is very little muck and consequently few aquatic larvae (Table 6.4). Semotilus; Notrqpis, and Bhinichthys are the predominant associated fish. 0f the total catch for this group, Etheostoma nigrum nigrum com- 1. only six of the ten "nesting plants" were used in 1957 while 13 of the 15 were used in 3-1. Those utilized were in back-eddies at the extreme edges of the stream in quiet water. 1.15 Fig. EcologiCal Group III 24 prised only 23%. Dense shade from surrounding woodlots render the bottom a dark color. Wild roses and red osier dogwood crowd the banks. From all standpoints, this would be considered a less favorable habitat for the Johnny darter. METHODS AND MATER IALS At COLLECTING TECHNIQUES 1. iohnny darters. collections made in augusta Creek, Michigan, between Sept. This study is based on seining 15. 1956 and Sept. 28, 1958. Nearly 2000 darters were taken and of these, 1200 were studied for such factors as age and rate of growth, sexual dimorphism, age groups, mortality rates, spawning ecological preferences within the stream and seasonal changes in the condition factor K. All collections were made with a one-man darter-net, Cfig. 2.1), except the collections made at Station 2 in September of 1957 and 1958. These were made with a two-man 25 25 six-foot common-sense-seine of %" mesh. These collections were used for p0pulation studies as the entire number of 245 fish (1957) and 300 fish (1958) were taken from one small area of the stream 80 yards long. Use of traps and two-man seines were generally ineffective. By means of the darter-net, fish lying on the bottom, between rocks, and among roots were successfully taken. Most of the seining was done downstream, but in some of the quieter waters, individual fish were sought by sein- Dng upstream. The latter method was used almost exclusive- ly at Station 10 due to the debris of iron, lumber, and Wire on the stream bottom. That the fish of this study represent a random sample is suggested by the fact that no effort was made to avoid 3'0 cky places, brush, shallow or deeper holes. The entire area of a given station was carefully seined. Fish of all 1el'lgths and ages were taken from nooks and crannies, in @391.) and shallow water, throughout the entire growing sea- BOrI. Due to the heavy matting of the algae which formed on thi’ inner surface of the net, fry as small as 20 mm. were eSally taken. At the same time, the technique used was adequate to capture the older and larger fish of 50 mm. The average length of the station was 100 yards. The maJOt‘ity of fish in this study were taken on the silt margins and sandbars located in six to nine inches of water. 27 2. Associated fish. Representatives of all associated fish were kept in proportion to the numbers actually cap- turmi. For example, in August 1957 several score of yellow bullheads (Ameiurus natalis natalis) were picked up in the normal seining activities at Station 1. Only a few hand- fuls of these were retained. The above method applies to flgtropis cornutus frontalis of most deeper stations and to Bgecilichthyscaeruleus caeruleus in the swifter rapids. These assOCiated fish were identified by the use of Hubbs and Lagler's Fish of the gggat Lakes Region (1949), then were wrapped in cheese cloth and preserved in 10% formalin. 3- METHODS AND mgrsngts l. §ex determination. The sex of each darter was de- teI‘mined by examination of the external genitalia and then by (dissection of the gonads. The males have a single palp 0P labium directly behind the vent; the females, two palpi (f is. 5.1). These palpi were not easily distinguishable in fish less than 20 mm. in length. Body color aided in iden- tif'ication only during the spawning period. All fish measured were also examined for gonad devel- °Pnu3nt. The method of rating the gonad growth as suggested bY'Il. c. Beckman and found in Lagler's Freshwater Fisheries EEEJEggy.(l956;14l) was used. This evaluates the condition °f tohe gonads during the spawning season as immature, ripe, or 3pent, and during the post-spawning season as immature 28 and mature. 2. Weight. All fish were weighed to within one-tenth of a gram on a Fisher platform balance. Before weighing, each fish was dried in cheese cloth for one-half minute (see validation of techniques). Newly hatched fry and fish less than 20 mm. long were below the accurate range of this seals and were thus recorded as weighing 0.1 gram. (fig. 2.2) -*fig. 2.2 Fisher platform balance 3. Length. The fish were measured to within one-tenth Of One millimeter with a modified vernier (fig. 2.3). This °°rlsisted of a vernier calipers fastened to a standard 50 ‘bhat the movable arm might pass over a fish supported on El block and located between the measuring arms. Each riSkI was placed on the support with the snout Just touching tn” ”zero-arm". The slider was then moved over the fish so 29 that its "indicator arm" was directly over the tip of the tail and then over the vertebral column terminus. These limits were read directly from the vernier scale and re- corded as total body length and as standard length. 4. Preserving; Darters, Aquatic PlantsL Esects, Algae. The darters were preserved in 10% formalin. The same solution was used for the aquatic insects. Some herbaria mounts were made of the less abundant aquatic plants for future study on this stream. Most of them were identified in the field. Fassett's Manual of lunatic Plants (1940) was used for this identifiCation. Algae were collected at Various times of the year and preserved in 6-3-1. Pres- °° tt's keys in Algae of the Western QLeat Lakes A_r_e_a_ (1951) 38I‘ved for the identification of these plants. 25. Validation ofggeghniques. To determine the validity 0f 'the methods for measuring the fish, control tests were °°rnaucted. The questions of how much excess water remained on 'the fish at the time of weighing and how much of the °Piginal body length and weight are lost due to preserving are; answered in Table 2.1 and 2.2. Before weighing, each fisti was wrapped and dried in cheese cloth for about 20 Seconds. This removed the excess water without drying out the lbody. To test this method, five fish, all of different "sights, were successively dried and weighed five different 30 times. Table 2.1 shows that the greatest difference be- tween any two weighings of the same fish is 0.1 grams -- and because the scales read accurately to only one-tenth of a gram, it was assumed that this method of drying before weighing provided good and consistant data throughout this study. TABLE 2.1 VARIATION IN WEIGHTS OF THE SaME FIBH WHEN hElGHED SEVERaL TIMES ONEAFTER THE OTHER“ \ Weighing tries .Fish Greatest First Second Third Fourth Fifth difference \No- --~___ 1 3.8 3.7 3.7 3.8 3.7 .10 2 3.1 3.05 3.1 3.1 3.1 .05 «3 1.3 1.3 1.2 1.3 1.3 .10 ‘4. 1.1 1.1 1.1 1.1 1.1 .00 \\““‘:?_ 0.2 0.21 0.2 0.1 0.11 .10 'wData given in grams. A‘q Cu, V ‘e . f! I U.. 31 A second study measured the differences in length and weight between living fish and the same fish when pre- served. The weight and length of a living fish were recorded and then redetermined once each month for four months in the preserved state. Table 2.2 shows that pre- serving the fish causes it to lose about 1% of its original length and about 3% of its original body weight. While these results are in agreement with what Van Oosten (1929) found for the lake herring and Shatter (1936) for trout, it should be noted that these observed differences could be accounted for as human errors and as limitations of the scales and vernier. No effort was made to compensate in this study for this loss of weight and length -- but whenever length or weights are compared, the fish are taken all from the same collection. 00 n ean03 hues ascamauo no whoa psoouom emsuo>< 0H u namCeH hvop Hecflmngo no mmoa unease; omsho>< 0H. 00.0 00.0 00.0 00.0 00.0 00. 0.00 0.00 5.00 0.00 0.00 0H 0H. 00.0 00.0 00.0 00.0 00.0 00. 0.00 0.00 0.00 0.00 0.00 0 #0. 05.0 00.0 00.0 00.0 00.0 00. 0.00 0.00 0.00 0.00 0.00e 0 it 00.0 05.0 00.H 00.H 00.0 0¢. 0.H¢ 0.Hv >.H¢ 0.H¢ 0.d¢ b 00. 00.0 05.0 00.0 00.0 00.0 Oa. ¢.00 0.00 0.00 v.00 0.00 0 00. 00.0 00.0 00.0 00.0 00.0 00. 0.00 0.00 0.00 0.00 0.00 0 00. 00.0 65.0 00.0 00.0 00.0 00. 0.H¢ v.00 0.H¢ 0.H¢ 0.H¢ v 00. 00.0 65.0 00.0 00.0 00.0 00. 0.00 0.00 ¢.00 0.00 0.0¢ 0 0H. 0a.a 0H.H 00.H 00.a 00.H I 0.¢¢ 0.¢¢ H.0¢ 0.0% 0.0v 0 00. 00.H 00.H 0¢.H 0¢.H 00.H 0¢. 0.0¢ 0.0¢ 0.0% 0.0¢ 0.0¢ a amoq .mmum .meum .moum .meum o>ad< smog .meum .ueum .moum .mmhm o>HH< .oz nsmua menu .can .>oz .000 .9000 .22. 0:50 .cmw .>oz .900 .9000 swam means 5 Emacs .ss S 533 nuswcsem $2 .8. shamanism. 20 H @5958 m>on< m .02 23.2.3 some amuse. mm: .efifimmamm as man 33 $83: as. mesaammm 30m 0. 0 W438 " l~w H 53 6.:50eile sampling. Scale samples were taken from the mid-bodJr on the left side at the tip of the pectoral fin Just belxaw the lateral line (Garlander, 1943). Other areas were tesst sampled, but this one gave the largest scale size withiniiform shape. approximately ten scales were removed and p1a<=ed in scale enVelopes. During the early part of the investigation, permanent mounts were prepared for rwading.. Later the scales were studied directly by plac- lng thenn in water and reading them under the low power of a coupounc1 microscOpe. A.fish was considered to be one year 01d wheri taken in its second summer. It would thus have °neifluuA1us and would have passed through one winter. It "35 cons idered to be in Age-group I and of a Year-class one less than the year of capture. Young fish taken be- fore the first of January showed no annulus and were re- garded as being in Age-group 0- Fig. 2.3 Vernier calipers CENTRAL JOHNNY DARTER A. GENERAL DESCRIPTION (1. Etheostomidae. Bailey (1956;369) lists the major characteristics of the genus gtheostoma as follows: Breast, interpelvic Space, and belly variously marked or covered Vith normal scales, but never with a. median series of en- larged and modified scales. (Pelvic fins separated by a Space which varies from nearly as wide as the pelvic base ‘0 less than half that distance. Caudal fin forked, t'1“m<=iat.ed, or rounded posteriorly. Lateral line, infra- orbital canal and supratemporal canal complete or incom- elete. vertebrae .52 to 41%) 2. general description of the gentral Johnny darter. (The Central Johnny darter is a small awl-like fish living on the bottom of streams among aquatic plants in riffles of moderate swiftness. The body is brownish above with small black or dusky "I" markings on the sides and caudal peduncle. The mouth is inferior and the lips are prominent in the 7 larger fish. The overly large pectoral fins and well-devel- Oped pelvic fins serve as "resting" organs 01' support. This fish moves with swift darting motions and often buries itself with only the large dorsally located eyes protruding ab 0V3 the sand. The body is somewhat depressed, being 34 35 flattened above and below. The body surface feels rough to the touch, this characteristic giving to the species the nickname of Sandpaper darter. During the spawning season the males are a deep velvet black and display various Iigwagging activities as part of the mating behavior. “any who have fished a stream for years are never aware of the 1r presence .) 3. Taxonomy. (considerable study has been made of the “rial and prOportional characteristics of this fish, and the following generalizes its taxonomy sufficiently well: lateral line complete or nearly so (Bailey 1956:3269); ‘here are more than 10 pared-scales and the scale rows on ”19 body exceed 40; pores of the preOperculomandibular canal are 9 or more; anal spine very thin, single and flexible; premaxillae protractile. There is a dark bridle on the snout which is interrupted at the midline. Breast, mflied; cheek naked or with few small scales behind eye; nape naked or with few scales. The scales of the Johnny darters completely cover the body except for the head, parts of the cheeks, and fine.) The eastern subspecies Etheostoma nigrum olmstedi (Storer) arm‘s only the cheeks scaly, with the nape and breast un- sealed. The western form found at the base level of the Great. Lakes, gtheostoma nigrum eulepis (Hubbs and Greens), has the breast completely scaled; cheeks usually moderately inner concern e: liner. al.1180315, L \ criteria ,_ BEL treat, an “M {m Q“ 00“ 30 M (The to hang \LQL titty \Q T! Q)“, If, I 36 scaled, and nape completely scaled (Bailey 1956). (The darter concerned with in this study is the Central Johnny darter, gtheostoma nigrum nigrum, and it shows both cheeks, breast, and nape as naked. It is usually upon these two criteria -- geographic location and nakedness of the cheek, breast, and nape -- that these subspecies are separated from one another.) 3 . SYNONOIIY {The following synonomy is taken from Check List of Fishes of North and giddle gmerica by Jordan, Evermann, and Clark, 1955. page 287. It. gives well enough the early generic changes. EOleosoma nigrum (Refinesque). Johnny darter; M Simon. Eastern United States, Ohio Valley, Great Lakes region, and upper Mississippi, west to Colorado and north to Manitoba.) Awostoma nigrg Rafinesque, Ichth. Chiensis, 1820, 37, Green River, Ky. flgosoma maculatum Agassiz, Lake Superior, 1850, 305, Lake Superior. Eliasoma olmstedi brevipinnig COpe, Jour. Acad. Nat. Sci. Phila., VI, 1868, 214, Kiskiminitas River, Pa. R‘Qgilichthys beani Jordan, Proc. U.S. Nat. Mus., V1.1, 1884, 479, Tabo creek, Mo. “I m was , l ‘1 ‘ ”—f 3,. ‘1 mini genus L we Johlmy dark There at gnu-,1 dam! hm hm ! ikles \F‘ thallium “Q silt: 2.; \ ~ “05“ {M \r 37 In 1956 Bailey (1956) proposed the return to the original genus of gtheostoma. and he has included all of the Johnny darters under this heading. C. GEOGRAPHICAL DISTRIBUTION. There are three subspecies of the Johnny darter; the Central darter (g. n. nigrum), the Eastern darter (E. n. gimstedi), and the western darter (g. n. eulepis). These are found most typically throughout the eastern United States (Forbes and Richardson, 1920). Here they are abundant and ubiquitous in their habitat selection. The two subspecies §theostoma nigrum olmstedi and Etheostoma nigrum eulepis have, however, accepted widely different habitats and are thus localized in their distribution. gfiheostoma nigrum olmstedi has the more easterly dis- tFibution extending from the Canadian Maritime Provinces 8(>1..1*r.h\m=trd to the Ottowa River. In the United States it 1nintludes the eastern part of the Lake Ontario drainage, "here in the lower elevations it intergrades easily with Etheostoma nigrum nigrum. Its southern range extends along “‘3 atlantic coast east of the Alleghenies to North Caro- lina. inhabiting the quiet waters and riffles of the 8"]filler streams. (Hubbs and Lagler, 1949). fleostoma nigrum nigrum. occupies the central area or this darter distribution. Its range extends from Sas- km'<>1'1ewan to western Quebec along the northern United States i i, n throughout} \. W3 Pie-erupt: ta iPPdhchi-e; than Iceman \ m the eqS’Verx EWOSM ~— ku‘j W “XE ‘m E“ .' Q tie it. 38 and throughout the Great Lakes region, except in those areas pre-empted by Etheostoma nigrum eulepis; eastward to the Appalachian Mountains; south to the Gulf of Mexico, then westward through the Arkansas River drainage systems to the eastern slapes of the Rocky Mountains. (ibid.) lgtheostoma nigrum eulepis is confined quite specifi- Cally to the northern lakes of the Mississippi River drain- age and to the base-level lakes marginal to Lake Michigan “1 Wisconsin, Indiana, and both peninsulas of Michigan. It is further limited to Lake St. Clair and the Detroit River; also to inlets and bays near the islands of Lake EI‘ie in Ontario, Ohio, and Pennsylvania. (ibid.) D. DARTQ HABITAT 1. general habitat. (The Central Johnny darter inhabits smalistreams and lakes, differing from other darters such 9‘8 the Iowa darter which prefers larger lakes and streams (Eddy and Surber, 1947). Occasionally the Johnny darters are, found in small rivers or shallow parts of glacial lakes (Adeims and Hankinson, 1928; Forbes and Richardson, 1920) but. in uichigan they tend to inhabit the small inland st'I‘eams and brooks whose depth is only a few inches in the Sunliner and whose bottom is dense, soft, silt-sand. Lariamre, Pickering, and Durham (1952) found the Johnny darzer in deeper waters than the other darters they collect- ed, and in greatest numbers in those areas where it was 39 associated with sandy bottoms.) Starrett (1950) in his study of Boone County, Iowa, reports Boleosoma nim nigrum (Etheostoma) as being the most abundant and widely distributed darter in the county, and that this Species showed no particular habitat preference. In the Augusta creek, however, this Species does show a strong habitat preference. It was observed at Stations 4: 5. and 6, that above the bridge construction which determined one limit of the station, there was a distinct shift in habitat type from that of the area.below the bridge. @pstream the water is deeper, slow-moving, the b0ttom sandy, and aquatic plants and insect larvae are abmldant. Here the darters abound.) Downstream thO water 13 8Wifter in character, shallow with rocky bottom. The Shade is dense and there are no aquatic plants, few insect larvae, and the silt margins typical of the weed matted “(198 of the area above the bridge are, gone. Here the darters are rare. Thus within a distance of 100', darters e9 7979)OC2)72' //j \\\\ ‘ 11m ,,,,,,, ws, (cockerell, 1913).) Raney et a1. (1948:231) State tbhat the scales of Etheostoma are much like those of StLZOSteedion, but differ from them in having no annulus on the lateral field, such as occur in the yellow perch and centrarchid scales. The radii are somewhat more numer- °u3 truan in Perca flavescens or stizostedign vitreum (Evans, 1915.) Fig. 4.1. Scale of Central Johnny darter 43 3. @nnulus formation. {It can be shown that a new annulus is formed each year in the spring and there is evidence to suggest, that the time of this formation is dependent upon three factors; (1) temperature of the water -- at least 17°C- (Hankinson 1919). (2) latitude (Haney et a1. 1943), and (0) degree of maturity.) Haney and Lachner (1945) found that the annulus did not form until after spawning in the older fish of gtheostoma olmstdi (Storer) and Etheostoma Engimanum (Jordan). (Table 4.1) That a new annulus is formed each spring is clearly evident. from a study of scales taken on advancing dates from the first of March to the last of September. These data Suggest that the annulus is completed by March 15th (see Table 4.8). Scales of fish taken from the same loca- tion (Station 2) throughout the year show wide circuli in the spring and early summer when growth is more rapid; “03°F circuli in the winter when growth is reduced or at a standstill. (see fig. 4.4 and 4.5 of Plate I.) Secondly, rm“ a study of the newly-hatched young it was observed that during the first spring and summer, the young showed the type or circulus pattern which is seen in the anterior parts or Older scales, namely between the focus and the first Year-mark (see fig. 4.2). Haney and Lachner (1943:2331) have interpreted "the point on the anterior field of the s .- cqle which is laid down between the cessation of growth in 4 4 .asaufi: a scab Abmmav ashmmm_ .noas .xmohu a .noh na as: ma .as: madman 00m ssoumoonpm magnum xeoau spasmsm : -azi; -rsz1::a%.:fi.tél-l?lrth sopmhm so «Haswaepsflw upam osmocoa Annmav A.xOmesv massaaonsflh .w.z .Lopmo no hampsnaau ma .aqd oxmq 00m envenoado uzoom hsoz .xoouu Mosam as: no it- - ...... '14 amen an .Aommflvcom masaaaonsaa steam ca nuasnoam massaaonmflw xcmoh ¢ £ monaoh e nanosepso mm -mm has assets Anemav «sausage .nm as: he: osom.mm to own gamma no Edam“: causaco oxsq eaouom no amsA umm as: was scam moauom.s= .saomooamm. xaow eoz hum so>sm Lash cesarwW 1:;ll seesaw s~-~ as: .saa Aneaav assessao amaam «can: .55: no daam< no :H.nxe hecnosq mmummm. xao» :oz sesamsm seams .mx: m pea name used N aha cad henna new mammmmflmm access no noflhspsnaaa Hausa an H Hausa Anemav saaamau> .x3 and costume .am4 a“ aocnosq .mmmm. no Eopmhm seesaw eaouom we» 902 .x: ama use henna .N0a .naddduddm. ao>am aoash aesnm awash open soammm.oo«aom magma .mmHusam moaoomm acapsooq seesaw usascc< madnnsmm seesaw was Losses .oz seesaw 5|:nsva anaemia.“ gamma magmas EE @3333 agkha as mmsamas azmmaaaaa so onaasmoa maqszz<.ao mass was d.¢ m4m<9 45 Fig. 4.2 showing spring Fig. 4.3 showing key and fall growth of circuli characteristics of three rows of subapical cells *Fig. 4.4 showing rapid *Fig. 4.5 showing slower Bl‘owth of male, growth of female, Auge-group I Age-group II PLATE I * Figul‘es 4.3 and 4.4 are reproductions of drawings of scales 46 the fall and Just before the resumption of growth in the Spring...as an annulus, or year mark." I have followed his interpretation and have designated these marks by Roman numerals. Scale data taKen from fish of approximately the same length and of different age groups show the relative rates 01‘ growth between the two sexes. The fish start out at approximately the same rate of growth. Soon, however, the male exceeds the female so that a male in its second summer 18 as long as a female in its third summer. This dif- ference in rate of growth continues until they are both in their fourth summer. Then the rates level off and death ensues . 4. girculi analysis. The circuli are laiddown with irregular spacing throughout the year (cooper 1951). Such f‘itct'Ors as water temperature and food availability alter their deposition. The first circulus space following the “mm-line is quite wide and is followed by two other such Spaces. Each space is approximately three times as wide as the Circuli spaces of August, and four times the spacing of November and December. On or near Mdy 1. growth is slowed “"1 for a period of approximately 30 days. This is during ”1° Spawning period when the number of circuli laid down per unit of time seems to remain the same but they are much closer together. Seventy fish. taken on June 6' showed no nl. 4 : = 0.00 a anhdnm nmzfi : = m.v¢ h = : m.mn S nozoam eoz o.vm : .Hosoo Haas n.sm a mdoaoo sosoac a.nn a on noes: .. .. eds a 33%;..zmmma E. ..--.. .. was a s s s on 2 mSHzOLHo a o.m¢ h s : H.vn h ao-oam so: oz on : agenda masons a.e¢ a osmaao masons m.nm : ma note: = s as a = = as w::ainpzzu = o.mn a e : aw h = = m.¢¢ h a : 0.0N : season .5:d< om .h cosuow .3CQ< 0m 5 weapon .sac< a.mm E m nous: II I-.. - ..|-|l .--ilrv'a. : : QOQN rm .. : Gown 2 astoum oz m.¢n a H none: Camuss madam .38 Kom mWwass canon !1umm umwm iI.mwwwss mamom .53 New 09d: .q.m .A.m .4.h uHH asoamnem< HH muoLMuow< ohms .mmdssma aza.mmm<: aszaaamzs as assess: H asoumuoms mafia ac 202.5:QO m5. 20238 @4323. $2 .8 an: N.¢ Mdm<fi 4a statistical difference between spawned and unspawned indiv- iduals in the average number of circuli laid down for both sexes. There is no evidence to suggest that growth begins after spawning. Rather it seems to begin earlier and is slowed down during spawning, as suggested by the closeness 01‘ the circuli. Further retardation of this growth is sug- gested by fig. 4.8‘ showing the mean length of Age-group I males for each month of the growing season. At the onset an increase of 0.3 mm. per day is normal. Thus an increase or 7 mm. for the period of lay 9 to June 1 would be expect- ed as shown by the dotted line. The actual growth achieved, 2 mm., indiCates a near standstill. Following the spawning Period, the normal "seasonal" rate of increase returns. Thus, on either side of the May growth period, there are 8inglelarge circuli spaces. One of these spaces, that an- t'er‘ior to the May circuli group, is formed about June 1 immediately following the spawning activities. Normal summer growth continues throughout July and Au- guat, with a reduction in number of circuli and spacing be- t"98n them. Then in August there seems to be a Jump in the growth rate. This I have called a "Bumper-circuli-space". (See plate 11.) This new growth is probably due to the in- crease in the abundance of insect larvae. Then begins the fall and winter growth period. Here the circuli crowd in “9°11 one another and become greatly reduced in number. Fin- ally by February, the year mark starts to form and is com- 49 .noaa .xoeao sumzws< .COmsom mcHBOLm ozooom one asonmsoanv Comma .4.m .53 we ”canon souflmonashm no mflmhamcs «asoaao o.v .mHL Campus oasom gueoam Lenso>oz naloam honoaoo A amdms< seesaw anasoaao Lomssme zasoam m.ho5§5m unooom a cash seesaw msasoaao somasms «asoaao cacao e .on he: a H >dx soon aatad sand Hata< naloum madame sea a sand nous: «asoaao n s msassc< use» and no Hash :aeoam m.a0835m and nasoumumcdaumcfinoadm msooh HH Hakim 50 plated by larch l. (Creaser 1926) B. AGE AND RATE OF GROWTH 1.(Population study. Fish (1935) reports the new-born fry as being 5 mm. in length. At the end of the first week, it is approximately 6.6 mm. and by the end of the first _ month, 10.20 mm. Hubbs (1921) gives the figure of .34 mm. ‘ as the rate of increase per day for a monthQ Spring-of- '_ the-year fish taken in buns 1958 showed a mean length of E 15.9 mm. with a range of 14.5 to 18.2 mm. when both sexes were grouped. Figure 4.6 shows that there is little dif- f6Pence between the males and females in the rate of growth for the first year. ("At the end of the first growing season, the mean standard length for the males is 28.5 mm. and 37.6 mm. for the females. This difference increases, how- "91‘. throughout the second year and remains about constant for the third and fourth year if this latter upper age limit. is achieved. Two-year-old males average 2.5 mm. lon- ger than females of the same age.) (fig. 4.5) While the males show an advantage in growth size over the females, the latter appear to show greater survival ”"91“. Thus Table 4.12 indicates that there is an increase in tohe prOportion of females per age group as the fish grow older. at the end of the first summer. the males constitute 51% 0f the first-year-fish, the females 49%. But by the end 0: the third summer, the females make up 60% of the Age- ‘1! *- 51. group 11, population. It should be noted, however, that while the figures suggest a slight increase in the pro- portion of females, these differences are not significant at the 5% level when tested with Chi-square. That this is the normal papulation change, however, may be indicated by comparing the sex ratios of other dar- ters with that of gtheostoma nigrum nigrum.) Thus Raney and Lachner (1943) in their studies of ggleosoma nigrum olmstedi throughout New England collected fish which included all four age groups. The percentage of females for Age-group 0 in New England was 43%, for Augusta Creek, 49%; Age-group I New England 43%, augusta Creek 51%; and age-group II New England 57%, Augusta Creek 607:. It can be seen that these Patios show the same tendencies as that of the Augusta Creek fish. (The upper maximum longevity of fitheostoma nigrum nigrum $8ems to be four full years. of life, 1.6. four completed Summers and perhaps the fourth winter.) Of the 612 fish t“ken by Haney and Lachner. three were of age-group III and these were all females. A similar collection of- 357 f 1811 made in Augusta creek in the spring of 1957 contained “ent males and eight females of Age-group III. A male. S'L- 58.2 mm., believed to have completed_its fourth winter, was the oldest fish captured during this study. It is in- t'eresting to note that the longest and oldest fish taken by 52 May and Lachner in Connecticut in 1943 was also a male, S.L. 88 mm. In September of 1957, a large collection was made at Station 2 and the mean lengths for each age-group per sex are given in Table 4.3. It was found that the mean length for the three-year-old females was far above that expected. Thus two more collections, one on October 12 and a second on November 23, were made at this same station. From among the approximately 200 additional fish, 6 two-year-old fe- males were taken. These showed an average standard length 01’ 43.0 mm. and a range of 5 mm. extending from 41 to 46 mm. These data fit more closely the mean length for Age-group II females as suggested in Figure 4.7;. Because of the close- ness of this fit, it is improbable that the inclusion of still larger samples would change this mean significantly. 53 spec honsepmem can ow cause one: Lense>oz was accepoo Eon“ swam assoHpchs sens m.¢¢ on amassed ms: esas> mane* *H.©¢ w.©¢ n.a¢ A.n¢ o.hN m.mm dea u I ma dd an an an on mcosaoomm no .02 I I I I IMOflNHII IIHfiMNIHI com IPHHPNH I I H ha a m as ea norm IHNNI ¢H ma no no Hm md be mv MG a¢ an mm an an mm hm mm mm Ch 0: Oh HHH .8 .h HH H .2 .h 0 VIZnIII'III III" I'lllll mamaosfiaafia names; anOLMnom< usnesssm soma .muH: .xmmmo <9m:¢:< .mmmamsa wzzmow mam ac anomcnmc<.moam deed Edam”: Aemmav EnamH: I I ¢o¢v 000v neHv Henv ”Lamomm “EOQWOWSJLM Anemav Loczomq sszmsamnoa n u n6... mém «.mn 0.5 can henna .msomooaom 7 Anemsv Homemade _ nuanced EdamH: o.mv 0.0m v.n¢ N.Hm w.mn m.vn use hocmm sEomooHom v Mk .2 1I‘:4M-w .3 .;.m .2 ftrult MVLLoBI. moaooam HHH HH _ H mQSOthow< omhnk mmem.mm v on.om m I I m H¢.¢m o Ob.mm o I I o mn.nm ma on.¢m @ I I e mo.¢m am om.mm OH I I n 00.0N Ow Om.Nn m I I ........HHIQ namaoe mm.mw ma I I I I OH mo.mm ea Om.mm m I I b 00.nm b I I I I m mfloom ab Om.mm mm ON.ON ha .........HIm mdseoa on.om OH ON.MN b I I n Om.mm ow Ob.NN b on.mH m m mm.bm He om.mm ow OH.HN Na d Summoq .sstlIEIeillmmmmmA .Esxa newcoq .mem see: .02 can: .02 use: .02 acoapuam was masons m pmsms< an hash em scan Hmoamoaoom AmthmquAHH 2H .4.mv .nmmsamu nmxmm myom .zmmHmon .xwmmo «Hmocat $3 4.22 .5223 623% 62835 4.2. 30mm 92.8.38 ngmiIkoézbg o.v wands 61 is not reflected in the growth achieved in the one-year-old fish as it is in thesunfish, for instance, but rather it shows up in the abundance of darters supported by any station or ecological group. There seemed to be no differ- ence in growth achieved by all age groups at the end of the growing season regardless of the station considered. Thus two-year-old males at station 2 averaged 43 mm. and those at station 7, 44 mm. 5. Pot-ItohatchixyggrowthL 1957 vs. 1958 It was desired to Know if the young-of—the-year in 1958 had an advantage over the same age-group fish in 1957, this advantage accruing from the 20-day advance of the spawning season in 1958. D1 1958, Spawning began early in April but was followed after a few days of high warm temperatures by the normal 001d nights and rainy days. Thus not until the middle of May were the expected spawning temperatures (18°C.) recur- rent, in the stream. Table 4.7. suggests that this early Period of hatching did not aid the fish, and that growth "as retarded until normal Spring temperatures prevailed. Thus had they continued growing during this 20-day period, they would have accomplished a 10 mm. increase over the exPected average for that date. The data, however, show that on June 27, 1957, the mean length for the young-of-the- Yea I 1" Was 20.2 mm., and that on June 27 of 1958, the aver- l. . some fish taken on June 25 were averaged into this data. 62 age length was only 17.8 mm. Comparison of the July and August collections for the same dates in 1957 and 1958 substantiates the statements above. (Thus it may be inferred that early or late spawning does not greatly affect the mean length for a given age group for the first year. Where cold weather follows the early warm spells which set off spawning, growth is checked until normal temperatures continue through the early weeks Of spring and summer:) Ten to fifteen days benus at the beginning or at the end of the growing season does not éaffect the overall growth pattern. (See Table 4.7) C . SURVIVAL RnTES 1. Theoretic natality. The fecundity of the Central IIOhnny darter is not high as regards fish in general, but is amply sufficient to maintain an abundant p0pulation in the Augusta Creek. The average number of eggs per female hi given in Table 5.3. (The older females lay two to three td-mes as many eggs as the smaller one-year-olds. Thus a 30kt11 one-year-old female would average 60 eggs laid and a laJPge three-year-old, 160 eggs;> At Station 2, within a run or’ 50 yards, in a stream area abundant with fish, some “Verity possible nesting sites were observed. Assuming that 8“(:11 of these were utilized by an average-sized female of “3 nmn laying 76 eggs, this area of the stream would pro- duce 1520 eggs. Actual field studies show this manner of 63 0986 madnoadn 2362 .N open masseuse Gees .H m.mm am am .saem a.am 00H am .eaem m.mm He a .mse n.em Hes m .me< m.mm as ea sass o.em mm as mass m.es as am ones m.om as am ease m.es nu ma ease m.oa mm as case e.aa s 0H ease o.na a o ease 0 00m mod as: m com mom sea 0 con and .sad 0 00m Hos as: .... ....s ..I-I---.-.....:. ..m I, I - Mam--. .a.m .oz ease .a.m .02 open Gee: adaoa cue: fleece mama sums .moHa .gmmmo seasons .msmzmemmm success we: .mmmd aze $2 a 233 misfismadoézsos so seem Eggs .3 zoaqusg b.v Mdmfih 64 reckoning to be inaccurate as the egg deposits are made more abundantly in certain areas than in others, such as ahead of rapids or small water falls. .4 further note of interest lies in the observation that when 10 tile pieces were placed in this same run of 50 yds., some 6,500 eggs were laid in a period of three weeks. While it is not known what porportion of ripe females successfully find "spawning rocks", and thus the real theoretic natality re- mains unknown, the data does suggest that where these Spawning places are available, an enormous number of eggs Can be laid within a short length of stream. 2. geological natality. (Only about 857. of the eggs laid eVer reach the hatching stage. Strawn and Hubbs (1956) hav. suggested that 90% of the eggs would normally be ferti- 112 ed, and field observations support this concept.) 0f the 9888 laid, approximately 1% develop a gr0wth of Saprolegnia within the first ten days. By the 14th day, only 85% of the original eggs are still viable. (Table 4.8) @arge losses may be experienced from predation of the blunt nose minnow (minincus notatus) which uses the same nesting site.) A 8°°°11ci factor, that of storage of spawning sites, lowers the ECOlOgical natality. Actual stream studies showed that many yards of the stream bed were inhabited by the darters with only one or two small pieces of wood, clam shell-‘3. 0? s . . unken stones to serve as nesting Sites. In those areas 65 Rom u acoEAOHo>oo no mhso «a Looms .mcanopsn as ammo manda> no emspcmoaom epsaaxohmm< o o 0 00¢ as an as: ea as 9 0s com «a as as: ma om as as m as con as am ass 0a a s a com a as ass ma s s 0 0s a ma as: as w a a o, , ..:mwm as em as: m a m o ooa as am ass m s a o oo oH ma as: a a.em a o o o on m ma ass a e n s 00H a ma ass a as ma 0 00H m ma as: n R when mmmm mmmm mwmm ammo . .02 ads :x: go new napsa>ca neon kudos no nousm seen .ahdo .oz cansa> useo Lem .>£ go .02 no .02 no .02 .oz .xoumq4 snma .zcewmoas .smamo «amass: .mmem43 szzmoa qsmazmo .593 44535 no 38 “32> .5 motszmommm m.¢ m4m88 1956 would normally represent 207, of the fall pop- “lat, ion. This difference between the observed 43% and the oxPteczted 20% indicates the success of this year class. 3- grOportfiion of age-groups in spring vs. fall seasons. “'10 differences between the abundance of the various age- groups as found in the spring and fall seasons is indicated by 00mparing the data of Tables 4.9 and 4.10. Thus it may be understood that during the winter -- and perhaps direct- 68) ’Olf . l . ultll... mflflok Imm4 r1}, .1 Isn't; l-‘|"\'ll. NN . 0 Na «we Nae mementos? a on boa .;-- ass as» masses a .m; 1w .I;w. :1 anw‘; w an aw..-n. -mm:i. 0s as .>02 - - - - om ea om an as as .soo - - as am as was we ooh mam mm .aasm Nil eEde e02 1.“ .1. ESQ emVsZL liWén tHEduQ .02 R efiflxm .02 £09.60 ‘ FDQH HHH-emma.ao.as ~H-mnma.ao.aw H-0nma.ao .a» o.smma sumac use» asses «sen poms .anamoas .mummo seasons .qaxa may 2H 5903.300 mafiafiq wzzmoh. mmm. r8 Abomaanmcdx mean .3 mcézmommm m.v 39w.“ 69 was?" nomww‘ fl 0 0H 55 a momshepd J_ 3 S was _ 0 man 338 . m o a m 3 mm «3 .. 0 PS as: n n on on so on .. o 3 33.1 3 ma nm S S on .. 0 so sous: u .02 “w . .02 a .02 a .oz :38 SK: lulllia :HMH JHH u I: .3150: «.309 mean zomém cagafim mma 2H maBMCQ Exes .mo mDOmOcmd< moatm ho Mwathzmomflm $3 .zaommoas £35 538... CH . hv H.499 |w 7.0 ly after the early frosts of October1 -- the three-year-old fish tend to die off and be removed from the pepulation. Two-year-olds of late September, October, and November, if they had lived through the winter to March 15th, would at this time be classed as three-year-olds; and the three- year-olds of the previous fall would become fish with four annuli. The number of three-year-old fish per 100 collect- ed in the spring is far fewer than the two-year-old fish captured per 100 in the fall. The two-year-olds of the fall represent approximately 8% of the pOpulation while the three-year-clds (after the new annulus formation of Febru- ary) make up only 5% of the Spring pOpulation. 1- F011 owing the first hard frosts of late October, I began to experience fewer and fewer large fish in the collect ions made in the same routine manner as in the Emm"Her and fall . 71 5. gex ratios. Twenty-three collections were made between March 1 and May 18, and 287 Age-group I fish were taken from selected stations representing each ecological group. These were studied with a view to determining if the sex ratio was different between the ecological groups or was essentially the Same for the stream as a whole. Table 4.11 shows these relationships. Chi-square tests show that for fish of age-group I, there is no reason to suSpect that the sex ratio is other than one to one, either within groups, between groups, or for the entire Stream , The same seems now to be true of the older age groups. Thus while the percentage of females within Age-group II and III is higher than for Age-group I, the sex ratios for these age-groups is not significantly different at the 5% level. (Table 4.12) 7.2 .aa .1 iii zadwmv .Hm>oH an ass as scaoaaaamam sozs n *H.m ".m.o - o.m A.soaemx H an.o an eeH an omH ham Hopes n so.m moassymano Ho 53m H 0.0 mm mm mm mm on HHHIH H o.m on on we on Na HHum H m.n me om hm mm mmH Hum .m.o oasswm moHesoh moHsz mcHssch moHsz anh macaw ano oouoomxm concomxm .oz .02 .02 gm: MMddenHmo ho mMDHc> 92¢ mammmaomwm HuH c_mfl323 amaomkxm nmmmzbz maHa. mmbomc 4¢0H00400m mamma ZN H maammumo< mm4<33h 924 mflqdfi ho mMmSDZ HH.¢ Mamie 73 .HopaH an on» as 0Hpsa oeuoeaxo HuH s Sou» asoaommHo hHacsOHuHsmHm 9023 soa.H . see. soc. otssra-aso “Om oe “Hm Roe Kmv NHm aseoaom emmno>4 me ma me an no as am .poz - - an we as on He .soo on me am we me as sea .saom ee Hesoh aoHsI aoHe—Bh meHsa eeHsaeh Q3 «.3 .33an rm 3 u R u N u u . 02 Sad uH u o unsoumuemw mmpoaeuuae ezuoza>a4 mama mensam me 2H aazamo NH . v H499 74 E. COEFFICImT 0F CONDM The coefficient of condition de was determined for each.¢age-group for both sexes, using the formula K = W/lj5 (Lagler 1956;159). Age-groups 0, I, and II for both male and females were collected from station 2 on September 28, 1957.. Table 4.15 shows that the coefficient of condition Changes slightly with increase in age and that both males and females exhibit a firm robust condition throughout life. TABLE 4 . 13 COEFFICIENT OF CONDITION K51, FOR JOHNNY DARTERS TAKEN AT THE END OF THE GROWING SEASON AUGUSTA CREEK, MICHIGAN, 1957 Male Female iHZG Kg' age K. w 01' Group 51‘ \ O 1.8 O 1.9 I 1.5 1 1.5 II 1.5 II 1.5 75 F. LENGTH-WEIGHT RELnT IONSHIP. The length-weight relationship was determined for fish selected at random from all three age-groups taken on September 28, 1957 at the end of the growing season. When separate curves for males and females are drawn, they co- incide closely. Thus curve B of figure 4.10 shows the length-weight curve when both sexes are plotted simultan- eously. This curve is based on the absolute values and curve ,1 upon the log-log transformation. The formula 1.03 I : log a + n log L was used to de- termine the intercept and true slcpe of the length-weight line of regression where values of a and n were .00002207 and 2.8983 respectively. The following formulae we‘re used '60 determine the above two unknowns; £8103 w)(1og LE] - ( i Log 17) ( 2 log L) where n : ([(103 Ma] - (1 log 102 N ((103 W) - niéuog 1.)] and log a. = N Thus where a given fish length is known and its weight 18 deg ired, the formula I : a. 1..n gives a reasonably close r“ for values between 20 and 60 mm. 76 Z /.3 A! 379” {35'3“ /-6 /.7 e ‘zo .J -v '3 -2 .I :2 /.6' .0 30 L93 in 5% Z7\°( ‘9 .. g /.b g;.«: 55 i4 ‘3 73 ‘1: {a a Q 3 1.; «Q 'A ./o 20 24 23 32 36 40 44 48 die 6’3 Mao/a;4/ [908/] in m-‘fl'me/er: Fig. 4.9 Length-weight relationship in Johnny darter of augusta. Creek, Michigan, 1957. curve B shows the absolute Values; curve A the log-log transformation. REPRODUCT ION A. SECONDARY SEXUAL CHARACTERISTICS 1(Spgwning coloration. During the last two weeks of March, the males begin to take on their characteristic spawning colorations. The cheeks, lips, breast, and back 0! the head become a deep bluish-black. The ventral and dorsal fins look slate-like in color, except the very tips of the spinous and soft rays. The caudal fin deepens to a Bray ish-black and the scales along the belly become spotted with black pigment. The female does not take on this black coloration but becomes browner generally. The seven dark bands upon the back blend into one another and extend Slightly downward along the flanks and the "w" markings become broader. The caudal peduncle turns a depper olive Swan.) in April 1958, pairs of ripe individuals were placed in btattery Jars at stream temperature of 12°C. These were allOwed to come to room temperature slowly and observations "'8 made on the behavior and coloration changes. Several pairs were kept at 4°C. as controls. llales whose fins were only slightly darkened when in the Stream now became very black and showed intense sexual bahshrior of wigwagging and territorial guarding. Approx- imately 12 hours after the temperature had reached 20°C., 77 78 males and females spawned. Several hours after spawning, a certain male had lost its blackish color and became a speckled brownish-gray. When, however, he was put into another aquarium containing 5 ripe female, the darker coloration returned within several hours. It would appear that this spawning coloration was a M~8hly variable trait, capable of being "turned on" or 'ioff" ‘18 a special sexual response. 2. genitalia. By April 15th, the genitalia of both sexes become distended. The two pa-lps of the female become erect, being pushed upward by an enlarged bursa which lies between the genital pore and the ventral fin. The body wall is en- larged and the scales slide pass one another. The male palp likewise is swollen, densely Speckled with black pigment at, ’ohe tip, and is somewhat erect. The genital bursa if present is much reduced . Fig. 5.1 Genitalia of the Johnny darter seen from the ventral surface. Left; Female Right: Male 79 4- -' —‘. , {Pan-rm.- .‘f- ‘ ‘3‘; 9‘ WY." ...- ( ‘ . ‘ yam :- - r 9 ...A "k“ I, U . . W. Fig. 5.2 Male 40 mm. showing sexual coloration april 15, 1958 'v *1!me? i “HM!"a -"~’-n3?- 53' v”. M‘ M 3% firmwaa h—fl‘ V 3‘: --— Fig. 5.3 Female 40 mm. showing sexual coloration uprll 15. 1958 80 B . QONAD DEV ELOPMENT l. éeasonal changes. Following the spawning act of May, there is a period of nearly three months before the gonads begin to redevelop to the point of producing grossly visible eggs. In the female there are present at the time of spawn- “6T , ...-“ ,_.___.-_,.. - E33” ‘ _‘ a” ing three"'sets" of eggs each at a different stage of devel- °Pment. During the spawning act or acts, approximately one- third of these eggs are laid. This leaves one-third to be ripened by next Spring and one-third as undevelOped. In the smaller fish there are fewer ripe eggs. (Table 5.5) COOper (1955) found in the Golden Shiner (Notemigonus crjsoleucas auratus) that maturity was apparently related to size at the end of the first year of life, and that within any one locality, maturity was dependent upon size rather than upon 380- This same characteristic of gonad development seems to be true with the Central Johnny darter. Of the 174 fish ex- amined in March, April, and may, all in their first spawning Y9“? and between 22.9 and 45.9 mm., 357, of the males and 14% °f the females were immature. All fish, male and female, TABLE 5.1 PERCENTAGE OF MATURE AND MATURE MALES AND FEMALES IN THEIR FIRST SPAWNING SEASON \— liales Females Wow I ,. __ an...” Asa-arena! ' No. No. % No. No. % No. 91 Wure Mature 1mmat.lmmat,Exam.Mature Matureimmat.1mmat. “8 77 65 41 35 56 48 as s 14 \ "‘In 81 over 31 mm. were mature in their first spawning season. One-year-olds, taken in the Spring of 1957, all born in the spring of 1956, showed a length variation of some 23 mm. This difference is a result of at least three ecol- OSICal factors which collectively serve as a strong deter— rent. to growth. a){§pawning date. The Spawning season is a month and a half long. some fish may have hatched by May 15, while Others are not free from the egg until June 15. Thus a fish bOPn on the 10th of June as compared to that born early in lay has a shorter total growth period until May of the next Year) ' b) spring-growth period. ”Since the biggest part of the “PS1; year's growth is in the early spring, a difference in birth dates is influential. Not only has the fish born on June 15 a shorter total growth period, but he misses the mHid. growth which takes place in the May 15 fry before the lat-er ones are hatched. This results in sharp differences in t'O‘tal fish length among the one-year-olds. Variations thug appear as differences in length, weight, and the state of gonad develOpmentQ c) pterspecies competition. The area inhabited by the p°3t~hatched Johnny darter is the same habitat as that of the y°uxlsz of Cottus bairdii bairdii, found in abundance through- c ut. the stream and occupying the same habitat as the Johnny a'C-nun-;\. on.” . . ‘ _-. s | a ‘ 'vq 82 darter generally. This competitor has, however, an ecolog- ical advantage over the darter because it hatches before the first of the darters. The two Species remain closely associated until the middle of July, at which time the Johnny darters move to the more sandy areas and the cottus to those of muddy bottoms. 2. gonad regeneration. In order to determine the rate at which regeneration of the gonads takes place, a standard- ized method for comparing the size of the gonads was est-v ablished. Thus two sets of comparator tubes were set up, the one bearing testes, the other ovaries. inch set of twelve tubes contained gonads taken from fish captured in April through March of the following year. Spawned gonads removed in July were rated as l and those in April as 10. These two dates represent the minimum and maximum stages of develOpment. After these two terminal criteria were estab- lished, the remaining 10 tubes were ordered according to gonad develOpment- Fish studied throughout the late fall, "int-er, and Spring months were then evaluated according to their degree of ripeness by comparing their gonads with those in tha tubes. Thus a two-year-old male, taken in September, would be identified as; male, II, mature; (devel. -5). Figure 5.4 shows that most of the regeneration takes place after September of the spawning year. Gonad development is 31 0" through the summer but speeds up rapidly during the 85 OH OH OH OH OH m.m m.m a.n m.a a.a v 0a .>oo mo .homohm .nm: .noh .cau .oon .>oz .Soo .paom .m3< keen ease as: .amt nude: .02 Ha 0H m m s m m w n m H ma ends .meoo mama mom<= mODQmmH bmma AHMhd .2920: mudm DZHmDQ ZflMHBma Qtzow mudmm>f N.m mania i u q...» a card. Mr.» A . . eon— . n ..Y .5: t ..p dung! to"... i.e....wll I ' nowasaocomon venom hanacoa mcagonm v.0 .mah S ..— h n 2 O m < h h I < A. ‘ q U ‘ 1‘ 1‘ \ 84 a” “ fl “ ' ‘9 w~lb d .lo'oEi O / 85 fall. During February, March, and April, the eggs enlarge, food supplies are increased, and approximately one-third of the eggs become ripe. 5. Fecundigy, Eggs become grossly visible during late august and early September. They continue to develOp ‘Jurough January and become fully ripe by Hpril lo. The 0333 in unSpent ovaries may be divided into three classes: Class 1, eggs fully ripe, possessing a large oil-drOplet, Orange in color and 1.5 mm. in diameter; Class II, eggs smaller (1 mm. in diameter), lighter orange and with little .focxi supply, no visible oil droplet; Class III, eggs less than .5 mm., whitish in color and without oil or food mater- Jhtl. Table 5.3 shows the average number of eggs of each Cletss for various fish sizes. In general the larger fish he)? more eggs, and my findings suggest that only the larger two-year-olds and some three-year-olds Spawn twice. Data l“Ken from actual field count suggest that 50 to 100 eggs Te‘tBLE 5 o 3 a-vamcs NO. or UNsx-aw-Ndo 1::ch IN FISH or DIFFERENT SIZES TaKEN APRIL 13 THROUGH MAY 18, 1957-58. (DATA GIVEN FOR ONE OVARY.) \ Size Total per Class class Class floup may I II ,M III sol-:55 mm. 96 so 27 38- 36-40 mm. 11:5 38 27 48 41-45 mm. 164 59 as 68 \ 8.6 are laid in one batch, depending upon the size of the female. (Tables 9 - 11) C. S éWNING 1. Field studies. In the spring of 1957, a number of "nesting plants" were placed at different areas in the stream. Pieces of broken drainage tile, numbered 1 through 25. were deposited in groups of five at the odd numbered Stations. In addition, ten more pieces were used at Station 2 and were lettered A through J, and a third set labeled 3 through 2. was used within a stream enclosure. In 1958, the nesting plants at station 2 were again studied. Tables 5.4 and 5.5 Show the results of these Spawning observations. seining collections and field obserVations were also made on “18 breeding grounds during April and May 1958 in order to 0hE’terve breeding behavior. Early in April, the males move out of the areas of d°°Per and swifter water to those which are shallower and “Owe;- moving. They investigate the new habitat and locate a flat stone under which they swim and take up their vigil. (Barley and Lachner (1959) and atz (1940) suggest that in thfi\03toma nigrum nigrum there is only one male to a nesting Site or stoneJ and that this is in contrast to gtheostoma EBLW olmstedi which may permit three males to share the Same nesting stone at the same time.(I found that any male Of , . gheostoma nigrum nigrum which has located his "breeding 82 t. a a finalist ...- Ii? m.ba ”mafinopsn on when gonads .>< mma "and: not ammo mo sensed .>£ 0H "Adsuamooova names we access Hopes on 3 S 22. 3 one. an as: can e 32. 3 3 An ease so onseoaoea ca seen dado as an: on em as: m as ea as n ones a ease as so: can em as: x an as mu m ease a anon on ass can as an: N an an on 9 ends a ones as as: on as an: a an S 3 n econ a one. 3 as: on 3 so: a 3 an an n edge a econ «a as: on on as: > a an on n ease H ones «a sex com ea an: a n on ea mm as: an ass on as: can as as: a e as ea an as: am as: as as: as ea as: e o on an am so: a ones as so: on as as: m n A.saoesaooea one as deans a an: 00¢ «a as: as e an em as as: am as: a as: on ea as: on n S 3 S as. 3 as: a sea 03 a as: 3 m as on a ones on as: a as: 0e a as: a a .00 .meos mcanoasm someono echoes: mama assoc canon .02 .02 Loss! on when coma one: cans oaoah open adeam noaem omsaobd nonesz «weak .xondqs .xoamgd madamoz mmm Emma mkz<4m GZHBmmz ZO mZQH94>mMmmO QAMHK ho nBADmmm «to "39¢ . “\ gainfmlia 4' , U nflnw.::ttrtmwws na as em as: an as: n as: on on as: a as as as as so: as as: a sea oon m an: a as man ea a so: A as: on seams ooo an Hands a an as on on as: «a as: on Hands con mm sands m ea as am ma as: «a as: as aaaaa con ea Hanna m as as OH on as: an an: n as: one a as: a on an as as as: «a he: an Hands an m as: a on as 0H m as: a as: am Hanna ooe em diode a ma ma as a sex, n he: an Hands can a son a as w 2 2 on Seas mm 2.34 as Sade. com S Sea: a 3 as ea on Hands on sagas ea Hands coo ea aaaaa a a ma as a as: n as: an Hana: 0H m as: m m an as ea ass ea as: a so: can a an: o a ea an on an: «a so: an Hanna on a as: o e on as an as: an an: em Hanna on m as: o n on On em Hates mm Hanna an Hates ooo ea Hausa o a ed on ma as: ed as: om Hedda com on sagas m n ea mm as as: ed as: as Hanna ooe ea Hands m m on on as as: ea so: on Hands com on Hands a a oo.meea wsanopsm ooxoonu canoes: owed assoc endow .02 .02 hope; 0» who: ones can: coda edema open endam noadm .hehd gonadz Hecah .xonaa4 .xOhamd mzapmoz mmm as: 223 cases 20 azozesfiamo 33 .3 23% 6.0 mamxh 89 stone", guards it against all intruders and drives off with ferocious attacx all other males who wander near his acclaimed territory. The site for the nest is usually upstream from a small or slow-moving rapids, at the side of the stream, and at a depth of approximately 8“) Fish (1935) reports finding nests in water approximately 1' in depth in the Great Lakes. (The bottom may be gravelly. marly shoals (Hankinson 1908), or stony and shallow (Bankinson 1952). Haney and Lachner (1959) found Sandy bottoms best) "Nesting plants" placed on one inch of mud in the Augusta Creek at Station 1 were “Gt used. Those on Sandier bottoms were most frequently em- Ployed and those over gravelly bottoms only oceasionally. N0 effort is made by the male to excavate further the natural nesting site. Something a little more than the ulicl{mess of the body is all that is required. Eggs have, howeVer, been laid on tile-channeling raised well over 1%" from the stream bed. The eggs are most commonly attached to flat stones about 5" across. Hankinson (1919) reports finding eggs on "ooden Splinters, mussel shells, and pieces of tile. several hundred eggs may be laid in one or more clusters. The 03g "patches" are about 3" in diameter. These are all c108ely packed and sometimes have one layer upon the other. Fleld observations suggest that the same nest is often used 90 by several females and that polygamy is probably the case. Hankinson (1952) reports having made similar observations. between May 9 and June 17, 1957, some 28 nesting plants were studied about every ‘7 days. Fifteen of these were successful and 2,000 eggs were observed in the field or brought into the laboratory. ObserVations were also made on aquaria-spawning individuals. 2. spawning dates. The spawning period for the stream beg ins around April as, when the water temperature. is approximately 1800., this temperature having been maintained for about four days prior to the early spawning date. Spawning continues until approximately June 10 with most of the actual egg-laying taking place between May 1 and May 28. (See Table 5.6) some one-year-olds spawned in the first TISBLE 5e6' 45AM ING DATES OF BOLEOSOMA N IGRUM BY VARIOUS aUTHORS Name of worker Year Location Egg-laying dates \ . Harikinson 1908 Walnut Lake May 16 - June 19 South Mich. F9rbes and 1909 Illinois Last day of April Richardson ' to first of June Hankinson 1919 Charleston May 1 - June 17 ll 1 inc is ‘ 91 week of may but no two-year-olds epawned as early as this. By May 18, all the one-year-olds had spawned and the two- and three-year-olds Spawned after this date only. By May 28. all mature fish had spawned once and some of the older fish twice. (Table 5.7) «3» Number of eggs spawned. when one compares ber‘ of ripe eggs of the different age groups with of eggs per batch as found in the field, there is d good correlation. The observations made on the tile showed that the eggs were laid in batches of multiples thereof. often several sets were found the num- the number observed pieces of 50 or together, each at a different stage of development, suggesting that several females had used the same nesting site. (Table 5.8) 92 I a OOH N mm mm mm on pH mafia OOH H mm ma hm do mm 05 o endfi a u mm to vm we mm mm mm ms: . .. o n so an em 3 3 as: - - o H 3 an me an a .3: .dm . adxm . am . ESQ . mm . 533 coceemm no >Lenno u 62 u .02 u .02 u .02 33 a: HH H mach no a an assuage «nauseouom bmma 48H: .vnammo Swan—03¢ 2H 3.319 .0 mzafi 924 m as: zamshmm madam a was; how .mo azsstmm mgtezmommm v.0 mqmda 93 madness: use: oom Aoomv ooe meanoaen use: 00m mnemoae>ec cow was moonmnmm< madness: use: 0nd mcaaoae>ee ova m can masaoao>oa ova M AooHV madness; use: oma madness: 00H w HH QsoaMnemt 1 messages on mcaaoam>oe com Acme . 0mm madness: use: on madness: on H Qsoamuom< assoc «assoc monoasm mmnoaem fleece sossm mamcam osmcam moasnpo asom cannon owned Assam mmwm omsm .oz mafidoo Uaowh 358 .83 seas .mmoaum mums azuammz 20 @2330 ms 59mg wzzmoa so 22:8 59368 m.m flqmda ' 4 .19”: .... “a.” p .. ..l Er. o‘f l 1.‘Iei1‘lr‘w.‘i . .hns>o eco Lou ce>Hw mH dose was .uedzsmm coco» bmmH CH cmeomHHoo one: :mHha mNH mm mm mm .53 on H m as: m - on ma «HH .ss mm H mH .sac H as an mm mm .sa as H nH .saa .H HnH so am He .sa «.90 H 9H .tas H _4 eoH am He an .52 m.ns H mm .ss: a as ma me mm as .as H.em H a an: H noH an an on .35 an H a ass H on em nH Hm .es o.mn H a ass H am an on an .ss e.mn H a as: H as om mH mm .95 on H a as: H .I macho -;3-:ummIMHmc :stzummtmnw .Es m.H newneq msoum mesa .oz hem HHH mesao HH mosao H mmmao .odmpm nemm CoHosom Hench mmmm audasaEH mmmm .Heben mmmm esam in: mm 2 Ha 2.82.3 gazes e392 95H 5 2238 8a m.n Hano one anon you ce>Hw mH some use bmmH CH copooHHoo one; anhs HmH no as as .as an HH m sea m mHH as an son .23 ca HH MH HHpaa m aoH no am no .52 an HH nH Hprs m nHH on an on .5: an HH nH HHsas m amH om am we .es en HH mm notes a am on em on .as an HH mH an: H 5 as ea em on .53 mm HH a an: a q. aoH an on as .53 as HH a as: m 00H as «H He .52 ca HH mH as: n as as mH an .55 an HH eH as: n eHH an em en .es an HH mH ass a emH on as on .as an HH nH HHsaa H shape .52 0.0 .38 o.H .Es m.H nmeeA;!1m1mLm one: .02 hem HHH cacao HH emsao H mmmao .chan Iowa :cHasam Hones emwm onzadaau mmmm .He>en emmm emHm . $.23 0v on on meozmq amo one new Ge>Hm moSHs> one .wnma one bmma mQHhso sexes ansa l'l ?‘| it 9" 'l ’I I- III oHH as a ma .3 3 HH 2 as: a HoH on a we .53 we HH mH as: n HaH om am we .25 we HH m as: m mmH an as as .as He HH m sea m mom om on «a .se m.me HH mm HHpaa m HeH Oh as an .as me HH nH HHsas m eeH we on we .35 as HH nH HHsa< m % 3H S 5 3 .as 3 HH 3 H2}. m eeH . as ow om .as me HH nH HHtac m omH no we as .55 as HH mm note: a mum mm on em .sa o.He HH nH HHsaa H 50H Ha as as .55 H.He HH nH HHtaa H hae>o .38 0.0 .33 o.H .Ee m.H namGoA macaw , even .oz and wHH mmeHo HH mmsHo H mmeHo .edsam .nems COHasHm Hence mmmm choosesu mmmm .He>oa mmmm omHm is .... s 2 as? asses .aHHHHH Has a sea as Ha.n Mange 97 4. Egg viability. Between May 19 and May 24, eleven new egg batches were discovered over a. half mile strip of the stream above Station 2. All the eggs in each batch were recorded. This included the living eggs, those with a. mold on them, plus those which were completely dead and white in color. For batches of 150 eggs there averaged 2 eggs with mold and 6 which were dead. The former were identified by the long white filaments which grew on the egg, and the latter were white and milky in color. During the first 5 days about 5.9% of the eggs become unviable and by the 10th to 12th day this has increased to 10%. Thus at hatching on the 14th day, about 85% of the original batch are still living and hatch successfully. (Table 4.8) In the laboratory, once a mold had started, it ran quickly over all the eggs and destroyed the entire batch Within 6 days. This was at temperatures of approximately 20°C. in the field (natural waters) it was observed that only a very few of the eggs develop the mold and that it does not spread throughout the other growing eggs. Occas- 1Dually, however, a batch of 60 to 100 eggs was found, all ‘883 of which were milky white and dead. These were un- doubtedly unfertilized.l 1‘ 1n the laboratory, females unattended by ripe males laid eggs in the normal way under rocks, and where there were no stones, upon the bottom of the aquarium. 98 5. number left unspawned. A short study was made on the number of ripe eggs left as unspawned in the body cavity of spent females. Twenty fish were examined and all had spawned completely. (6. spgwning act of laboratorl mating. Preliminary to the spawning act and as part of the courtship, the male in the presence of a ripe female begins wigwagging his pect- oral fine. This is done slowly at first, only several times a minute. Later the wigwagging becomes more rapid and vigorous. Often this act of courtship is initiated from within the "nesting house”. Then with short violent Jerky motions, the male nudges the female toward the nest- ins guarters. This he does by biting at her caudal fin and butting his head against her caudal peduncle. After several failing attempts to inveigle her to enter, he may x‘Oturn to the nesting site only to begin the courtship activities again. Once inside, the female then makes several passes up- sSlozle down along the surface of the nest roof. She may °ither brace herself with the stiff dorsal fins, or by the act, ion of her pectoral fins remain for a brief moment prfissed against the mid-roof without support. The male “manwhile keeps up his sporadic wigwagging. After several momerlts rest, the female then inverts her body against the mdersurface of the "nesting rock" and deposits several 99 minute orange eggs. The male follows her in an inverted position and fertilizes the eggs as she moves about. Once initiated, the egg-laying may continue for several hours.) (The eggs are about 1.5 mm. in diameter and are laid side-by-side very closely packed together. Several batches containing 600 eggs are sometimes laid without overolap. in areas too small to accommodate all the eggs to be‘ laid, a double layer is employed. At the completion of the spawning act, the male guards the nest and Cares for the eggs. (Hankinson, 1908, 1952; Adams and Hankinson, 1928; Seal 1892, ntz 1940) This guarding continues unceasingly and he drives from the ill-reel all other males. Mame and Hankinson (1928) suggest that this guarding is really territorial defense rather than an actual guarding of the eggs. While engaged “in this care, the male directs himself in such manner as to hflVe his tail lie under the eggs. He then moves, his tail back and forth while holding his position with his pector- 318 (Atz 1940). This stirring action apparently aeriates the water and cleanses the eggs. Newly laid eggs brought into the laboratory and left unaeriated quickly developed a. white mold (Saprolegnia) E) A.c3smm on he: pom on mason NH you use: cease 0: .sse as: so code eds: .csmmm nod casozv hounds .m Loaunc.d .ooma ma m as: .E.s m m A.heausc soncasm ca amouopca on £00» odds henna «conduou oasamu was vodka was: .easa no: casogv Lowhsu .m Leausc.b .ooma ma n ma: .8.s m a Assasmoh ozv - - .hs amass .Ho aso> .ooha-oe ed as deems .s.s «a m mm .ssn.so nod - .s.a o ssosm xosam .oosa «a om Hausa .s.s 0a a no .ss so ooh .s.a o .s.a o seosm xosam .ooea-os as as sass: .s.s OH H 0 m 3238. o5 .. .. 55.8 ..B .233 .oomm a .8 3.14 .s.s «a a Amuasmeu ozv n I .Ln xusa xodam .oomm 0 ma Hau1< .s.d m .N A.:uoa aXes aqua mmv es .san.mo «ma .s.a n .s.a m .ss xhsn .Ho aso> .oosa a ma assoc .e.s a a Assassos oz“ . - seoam .Hh aooa .uomm a ma Hausa .s.s 0a m an .as mo..o~a .s.s n .s.s ma :sosm .ao aooa. .oomm n ma Hausa..s.s oa a agape .A.m dang wcaasq we: oHsth eds: .maes .02 span cage .02 tom swam was -mas sodossoaoe 0mm seas sass ummu «cook oaak mBZDoo cow Qz< mama ozuzsamm Macadmomdq Sin 39a 101 D. HATCHING 1. Embryonic develoyment. In the spring of 1957, sever- al nesting plants bearing freshly fertilized eggs were brought into the laboratory and their embryonic growth was studied. Every day until hatching, one or two eggs were preserved for future study. Following hatching, samples were removed every second day. Upon study, the details of their develOpment were recorded. (See Table 5.13 for Summary of this develoPment.) (The ripe central Johnny darter egg measures approxi— mately 1.5 mm. in diameter. There are present a large oil droplet, yellow yolk material, and a thin egg membrane 1which swells quickly in the presence of water. The eggs reu‘uire constant circulation of the surrounding water in Order to receive a sufficient oxygen supply. This is ufinally accomplished by the male who beats his fins and tail while guarding the eggs. Both unfertilized eggs and uI‘Auaeriated eggs quickly develop the mold Sagrolegnia. Strawn and Hubbs (1956) found that normally about 90% of the eggs laid in their natural habitat were fertilized. 1319 percentage of growing embryos within batches of 100 or more eggs which the author studied in the field compared f<=urorab1y with this figure. Not all the eggs laid remain lttached to the substrate, for the male knocks off many While struggling to keep at the side of the moving female. 102 .asmaoa soon assos one Lou no emstm>m mohosome masmnov shoe and goods some momusa and“ asuopoea massacm> and omusa names «.83 o newcoq om mass @a venous: .coxoun ease mmo «Hanan poaaouo aao “Medan toaoo mmcoupm aceaepos zoom on mass ma madness: usoz .oeaoao>eo Hams ad odouucdu "Has: hoop Hanson :« aceamwa uxusd hue> to: mmm ma have 0H vacancwh .mcaansouao ma cooan ass muoupm mu amen annex «hexoasu meme «weaken ad ocoao>oa ma mane a anon ausem .Lsoaam on madczamon acoamaa assesses nose aoaaouv ado “anon on mcancdmon swan mmcauuehw pa mass e mauuuezw has a ouoaoamsam .83 m.a .sau momhma aoaAOLc Mao memento no uoaoo sawda a mmmm ma mass 0 msacemam moaumnnoaosusno canohhnem .o mootmen acoeaoaopoa onesaoaopen .mfima one no cams no emsam .mmma mZOHB<>mMmmO HM094m0m<4 .xmhmda MZZIOfi Admezmo ho 8233m04m>ma onoammIH 3....“ 339 103 Further, some eggs may be eaten by the male or female immediately after being laid.) This was observed several times in the laboratory. The incubation period is approximately 17 days depend- ing upon the water temperature. Jaffa (1917) gives the incubation period of the Iowa darter in the laboratory when the temperature was 13°C. to 16°C. as approximately 18 to 26 days. These darters were 3.4 mm. long when hatched.[During the incubation period of the Johnny dar- ter, the egg remains round and it soon appears a darker orange. Two prominent black spots are the embryonic eyes at 8 days. The body trunk is conspicuous and the myotomes become visible at 10 days. Prior to hatching, the oil dr0plet becomes reduced and is very nearly absorbed by ha tching t ime D (a. Post-hatched frl. Fish (1935) lists the following as characteristic of the post-hatched larvae: fry are about 5 mm. in length; mouth very inferior with the upper ,jaw PPOJecting; a large silvery black eye; myomere count of 15 to the vent plus 19 to ‘42 behind the vent, and an em- hr‘lronio marginal fin fold which originates directly behind the head. At the 5.6 mm. stage, the fish is characterized by Very large pectorals extending past the middle of the yole‘ ..7\_ 104 region and by large well-imbedded eyes which have moved higher upon the head. In the more advanced stages, the protractile pre- maxillaries and single anal spine help to distinguish the individual. The adult characters do not become apparent until the 15 mm. stage is reached, but by the time the young females reach the 35 mm. stage, adulthood is attained.) ECOLOGICAL ANALYSIS A... A SSOCETED SPECIES 1. Associated fish. Fish were collected from each of the ten stat ions during a ten month period, extending from April 15 to Nov. 2.0, 1957. Unusually high water prevented Some stations from being sampled once each month. The Species were sorted and recorded for each station. 'A longitudinal distribution of these fish is shown in Table 6.2. By lumping together the total catch of those Stations making up a given ecological group, the three me at abundant species in any ecological group was deter- m«‘Lned, Table 6.1. It can be seen that E-I with its slow- moving waters, sandier bottom and abundant aquatics, stands in direct contrast to E-III in its capacity to produce Jol'lnny darters. This latter is characterized by rapids and gravel covered with fungal and algal growths. E-iI, having ecologiCal differences halfway between E-I and E-lil, shows an abundance intermediate to the two above groups. gtheostoma nigrum nigrum was by far the most abundant fiSh taken, constituting 41% of the total catch. Then f0Llow semotilus, Einiohthys, and gotropis in that order. Ecological Group I produced 65% of all the Johnny darters; E‘II. 24%; and 13-111 only 13%. This shows that gtheostoma 105 \\ \Rod adamaconu 3552.30 admonomm \\\\\\\\ Rom - sumac Emma: asaamoenam. m.o.v.n mogm \\\\\\\\Saen messages: 3. .3385 see as w wmww\ “ma magmasossoaas .s msauaosem m \\\\\§\\ Ram nah modes mdadvmhas m 3.332383 Cairn mmaam \\\\\\\\\\\\\\§ «on 3 «sopnoonsm. 2L. :um NRO asasasomaosaa 2.. adaavosom e\\\ no «natans «Hounds assemm. m.m.a noaam ..\\\\\\§\\\\\\\\\\\\\\\\\\\\\\ «.8 ease sees: 338.54 8: _ 7a woo woo Rom R0 asoum boa moaoeam noose macho asoucum s33: noose 133 no R assesses pmos manna «neon. adeamoaoom puma .mo 49m3034 .maomc 4<0H6300m $0.1m ZHEHP mmHommm 9245239,‘ smo: was ~.c mqua 107 xxxxxxxxxxx x>¢x>¢x:xu:x>< x>¢x>¢x>¢x> mQGflOHLOBQ Noam ...........................HBHH thED ..............m:ps4:osanouwdc mdxoaom . o . o . . . . . o . . . . . .mafiHOSHdm ”SLOQQOLBN . o . . o o . .flowSOH CU dQHSOHOfl QSLOAAOHOAN meaoexn OH m m b m m o n N H acoaaupn Tamoém Ginsu Ssfiz 30:63 .Sma .5633: Janus «Secs... .3 5: 5948034 no 2023253 qsfigfiozg N6 33..“ 108 nifl-um nigrum exhibits an ecological preference for sandy, weedy areas in contrast to shallow, rocky rapids. 2. Aquatic Plants. Aquatic plant collections were made during the summer of 1957 and the spring of 1958. The Species, relative abundance, and their distribution throughout the stream were recorded. Table 6.3 lists the more common forms found in the stream prOper. (Reference to envirograph (a) of figure 6.1 shows a Strong correlation between the Johnny darter and aquatic plant abundance. The rotting root stalks of m, Nuphar, and Sagittaria provide good areas for hiding when being pursued. Also the plant parts of floharis, 1&8 turt ium, and Potamogeton form a deep organic medium in Which the insects abound. Thus these contribute indirectly to the food source.) In such stations as 6 and 9 where the mil-lat ic plants of the stream prOper are reduced to a few scatot-ered, isolated plants, the Johnny darter population is likewise limited to a few individuals. 109 masco>hd anode: H¢H mum” mdmudnHmH 3 desvuoo daueveecom msz _dsopd«n 34HOMmmOHmwolnfim 1 $3 249 so; . enema e339. so mamas mags 2258 m6 Ema 115 B. ENVIROG H8 The effectiveness of the relative abundance of seven environmental factors within the stream is shown graphically in fig. 6.1 a-d. The graphs show a strong correlation be- tween abundance of aquatic plants, a sandy-silt bottom, moderate rate of flow and depth, as opposed to rapids with a dark, gravelly bottom. Other factors making up the en- vironment such as temperature, oxygen concentration, pH, and water hardness seem less effective in determining da. rt er abundance . it“ 116 Amassam seaward .aa .d4 ”season He>shm .uo “Bod“ no mass .»m «anew oopsaoomms .& .mhd Newman .ma4 «scopes mucus .om “names .QQ «tsetse handed .o.ov .mwsaans: Hsoamodooo msoaus> mo azadnmohapno mcawonm H.o .mah Ado loo ‘W ch .flh We” IV “0‘ ...K 8‘ 4» h. 117 C. ABUNDANCE (Despite the very high numbers of successfully hatched eggs per spawned female, the darters do not become overly abundant, due, I think, to shortage of food for the newly- hatched fry. They cannot successfully eat even the small- est of midges. Food for these fry must consist primarily of algae or large infusoria, both of which are available in limited amounts in those areas where the fry are hatched. These areas are usually sandy or silty with a slight current under the nesting stone. Thus there is considerable com- Petition for the limited amount of food. Because they are hatched in only a few inches of water, they are not eaten by other associated fish, as these latter Seek out the center of the stream with its deeper channel. The rainbow darter remains in the deeper rapids, the blunt nose minnow in the stream channel,and the black sided dace in the shallower rapids. There is, however, evidence to s“Sgest that these fry are eaten by the larger darters fre- iuenting these areas. as the fry hatch out and begin moving around upon thesilt shelf or leave the egg case in the Presence of the guarding male, they are quickly eaten. Once beyond 15 mm. they continue on to maturity or death from disease or perhaps crayfish predation.) 118 D. DISTRIBUTION The most limiting factor of distribution is that of stream gradiant and secondly, texture of bottom material. The stream gradient introduces three controlling factors simultaneously; (1) the swiftness results in a broken sur- face and rapids-like environment which is strongly inhabited by the larger, more aggressive rainbow darterl; (2) the bottom contains neither sand nor silt but remains very peb- bly to stony which bottom is avoided by the Johnny darter; and (3) the aquatic plant abundance is reduced. Thus a rapids affords competition for food, and territory; lack of protective coloration from the background; and a more limited source of food dependent upon the muck of decaying plants. (The most perfectly adapted habitat in the Augusta Creek for the Johnny darter is thus a quiet to slow-moving area, about 6" to 8” deep, over a sandy to sand-silt bottom, at the sides and margins of the stream, in areas brightly lighted near heavy bottom vegetation.) The larger fish tend tooccupy the deeper, more sandy holes (Table 6.2) but the bulk of the pOpulation is found in areas as described above. This habitat preference varies somewhat from what Trautman (1950) found in Ohio. While the larger fish both in the 1. Laboratory observations made on these two fish in the same aquarium showed the rainbow darter Poecilichtgys caeruleus c. to be more aggressive and to defend a larger territory. , v . . . . Q . e v ' ~ ‘ I V . A . . I ‘ i ’ . . c' - ec_ 0 w ‘ I . . e, v . v ‘, e- » . . e .. o .’ . ' | . .' ' V, . ‘ ' u ' _. , ' _ x . . . - . h w . .1 " . o " . v o . I w . ,rl- ' . . v v I . . .~ v . . I Q ' . . ..' _ . . _ . ' . ~ 1 - . 1 .l ' .- . ... . D ~' . . . i e I x a S . . w . . o . . . q ‘ . . e . _, . 'A . I . ' . , p . O . D . . .e. , ‘ o .. i .V A V .v a. I, 1‘ . i .I O . e . - A . u I ‘ ~ . . .1 . 1‘ " ~| ‘ 119 Augusta Creek and smaller Ohio streams seem to prefer a sandy-gravelly bottom first, he suggests that in the Ohio stream they accept a "gravel-boulder-bedrock* secondarily, and in preference to a silt bottom. I, however, found few to none on the large rocky-boulder type of bottom, and took ‘tremendous numbers, particularly spring-of—the-year fish «mff the silty margins. This would suggest that "preference Inabitats" are correlated with size. There seems to be no severe competition from the asso- ciated fish. There may, however, be slight predation upon tale fry from Northern small mouth bass, Micropterus §g>lomien dolomien (Haney and Lachner 1943) and from the pickerels, Esox app. (Hunter and Rankin 1939) which use the JOhnny darter as supplementary food. Competition may also occur between the Northern Common Shiner, NotrOpis cornutus Lrontalis, mborhynchus, and the Johnny darter at the time 01' spawning. The former spawn at about the same time and jJilz‘elatively similar habitats. Because of the multitude of POSS ible spawning sites, however, this competitive pressure 13 vGary low. LPerhaps of least ecological importance is the variation h) cklemical and thermal factors from the source to the out- l.t" Table 1.6 shows very little variation in such critical famt-01’s as temperature, oxygen availability, and pH concen- t rat-ions. All remain within tolerable limits. Normal lower 120 limits of oxygen at 5 p.p.m. (Lagler 1956;254) were never exceeded. Jewell and Brown (1929) recorded pH readings of 8.0, 8.2, 8.4, and 8.6 in Michigan where darters were cap- tured and coker (1925) took specimens at concentrations of 7.2 to 7.4. Jewell and Brown (0p. cit.) felt that a range of pH 7.2 to 8.6 as found in natural waters did not affect the distribution of fresh-water fish. The other chemical factors measured were alkalinity and 002 and these remained relatively constant throughout the three year period of study. while there is a slight gain in alkalinity from head waters to outlet, this shift is slight and offers no limiting pressure. That the darters are found in such chemical environ- ments should not suggest that these factors determine their distribtution -- but rather that they have wide ranges of to l erance . 13'- EQQJLOI" JOHNNY DARTE (a number of investigators have studied the basic foods of the Johnny darter, (Forbes 1880). None, however, have done so extensively and this study yet remains to be done. Thus there is little known about the differences in food Preference between the young and older fish, between the availability of the food and their chosen habitat. There is ' however, some evidence to suggest that the shift in mi . c"‘°~hab itat as a lateral movement experienced during July 121 and august is correlated in the younger fish with their new food requirements as they grow during their first summer. Thus Fletcher (1957) has suggested that the newly hatched fry require infusoria for the first week, while Kidd (1929) reports finding colonies of algae and diatoms in the stomachs that he examined, among them being gomphosphaeria, Qleosphaerium, glosterium, Scenedesmus, W, Mi..." fliscus, and gagilaria. It should be noted that these are found in the small eddies, inlets, and upon the silt shelf; the QXact micro-habitat of the newly-hatched fry. Heimbur- 391‘ (1918) found that the food of the adult Central Johnny darter consisted almost entirely of the larvae of chirono- midae, while the young eat mostly Entomostraca. He further noted that the young eat more of the chironomidae as they b°<><>me larger. An early study made by Pearse in 1921 coxlearned 10 specimen taken in June and July from Wisconsin lakes upon sandy shores, and he lists their stomach contents as being 78% chironomid larvae, 3% Helea larvae, 2% maggots, 5' 5% cyclOps, 15% ostracods, and some sand making up about 0‘5%. The insect data collected over a three year period from all ten stations shown in Table 6.4 shows the availabil- ity Of this food in Augusta Creek.) 122 ma . . . mvoomupmo men 0 e e e WQOHOEO m . . . . snowmen n . .es>Lsa madam we . . cabana estuac vasomotano daemoeaom anma anthem mmach osu«Eocotano saomoedom. mama Lomasnauo: a 333. Bataat deenomosoacm daemooaoa. mama aomasnsHom maoasae mas mamas Bahama i aflohouudn «Eomoedom mmma dUHx Edam“: daaoasucu daemooaqm puma Lonoaeah R vooh medoeam use» LoasmHemo>CH ospasq mmomaa< mDOHm<> Mm zm>Ho m< mmamda wzzmow ho 0.0 mamsB mock camdm 123 F. EREDATORS (in their study of predation on the Johnny darter 4§91eosoma nigrum olmstedi (1942) and in their investigation of stomach contents of the fish of streams of Central New York (1942), Raney and Lachner found that in 31 stomachs of the Yellow pikeperch Stizostedion vitreum vitreum, 81.6% had recognizable Johnny darters (ggleosoma nigrum olmstedi) and this quantity constituted 80.6% of the estimated volume of all food. Further, these darters represented 61.4% of the frequency of occurrence of all food. They also found it as an important item in the diet of the northern small mouth bass (ggcropterus dolomieu dolomieu) where these two occur- red together in the streams of Central New York. Hunter and Rankdn (1939) found it as the food of the pickerels (gggx £22.). Embody (1910) observed that grgleosoma nigrum nigrum served as food for the King Eider.) 0f the 2,569 associated fish taken throughout the en- ‘tire stream, only two Specimens of the northern small mouth luass (all immature) and two small specimens of the mud piCkerel (isox ameriCanus vermiculatus) were captured. Therefore it is concluded that predation from such fish is slight. (Real predation pressure may, however, be experienced frxnn the blunt nose minnow (Hyborhynchus notatus) which Hggucinson (1908) reports as a most persistent predator of ,’ . r t ' U ‘ . ‘e . O 4' v, , w . . .' b . . O. . - . . ’ ’ C ‘ ‘ 1". . . v f . , ._,‘ . II o ' c I ‘ w .‘ . ' ~ ' u a ' V ‘ '. l o' . , -. - a ’ V 4 w . . -, I ~ ' D , .‘ _ t v _.e .» . . SL ~ , v . . _ . . -, _ . . , _ , . . ‘ .o_ _. I 1‘ ' » , . . , V . i l t I . . v, Q 1 n ' . ,y . i .‘ ‘ l ‘ I, t . ,. a . _ ‘ O - . “ t. C t 9. . . ‘ I I t l 1 . v F . . O, ‘ a ‘ u ' l a . G ’ J " l I . r .. - . I , . ‘ I . I . ( I O \ A . . .1. t . o a ,. .4 g I _ , _ a . . . I .. — . . l . . I 1 K . . . . I 1 . 124 the Johnny darter eggs. This fish was taken abundantly throughout most of the stream. Abbott (1873) reports finding Boleosoma olmstedi in the claws of a crayfish where it was captured when hiding. This is perhaps the one important source of predation) In the augusta creek, the crayfish are as abundant as the darters. Any weakened specimen or any specimen which is morphologically handicapped is quickly eaten by this ever present death trap. The darter's defensive pattern of scurrying under stones increases its vulnerability to capture. Into the waiting claws of these crayfish the darters swim as an avoidance reaction to some lesser out- side danger. Thus the pOpulation is constantly being reduced and the weak and dying are quickly eaten. That this is so is seen he the fact that of the 65 fish tagged, clipped, or in some other way impaired, none were ever recaptured. 125 G. DisghES (little is known of the diseases attacking the darter group. .atz (1940) found ichthyQphythiruis maltifillis (Fouquet) to be the cause of death of a darter which he had in his aquarium. Many trematodes, particularly in their earlier stages, attack the Johnny darter) Among these are Neascus Vancleavei and égygia angusticauda. Cestodes such as Ligula intestinalis and Proteocephalus amblOplitis and acanthocephalans such as Neoechinorhygchus cylindratus and Lgptorhynhoides thecatus have been reported in darters by van cleave and Mueller (1934). (The well known "Black pinhead" parasitizes the Johnny darter and two and three-year-old fish are heavily infested. The older females appear to be more densely covered than smales of the same age.) Fish taken from stations of E-I are more heavily infested than those of E-II. Cit would seem from this that the slower—moving waters of Station 1 éuui 2 plus the heavy silt bottom harbor this parasite to a more prominent degree than the swifter and sandier bottoms of station 8 and 105 REFERENCES CITED Abett. C.C. 1873. Notes on the habits of certain crawfish. Amer. Nate, V010 7. 1873’ pp 80-840 Adams, 0.0. and Hankinson, T.L. 1928. The ecology and economics of Oneida Lake fish. Bull. New York State Coll. Forestry, Syracuse U. l (4); 235-548. Adamstone, F.B. 1922. Rates of growth of the blue and the yellow pike perch (Stizostedion vitreum) in Lake Erie. Univ. Toronto Stud. Biol. Res. Lab., No. 5:77-86. atz, J.W. 1940. Reproductive behavior in the eastern Johnny darter, Boleosoma nigrum olmstedi (Storer). Copeid, NO. 2.100-106. Bailey, Reeve M. 1956. key to identification of fishes of Iowa; found in Iowa fish and fishing by Harlan and Speaker, 1956. State Conservation Commission, lowat Baten, W.D. and TdCK, Peter I. 1952. Relationships of weight and body measurements of adult smelt, Osmerus mordax (Mitchill). The Pro- gressive Fish-Culturist. Vol. 14, No. 2, April 1952, pp 50-55. Garlander , Kenneth D . 1943. Length-weight relationship of Minnesota fishes. Minn. Bur. Fish. Res. 35 pp, typewritten. cockerell, T.D.A. 1913. ObserVations on fish scales. Bull. U.8. Bur. Fish. 32(1912) 119-174, 9 p1., 52 text fig. coker, R. E. 1925. ObserVations of hydrogen-ion concentration and of fishes in water tributary to the Catawba River, North Carolina. Ecology, 6; 52-66. 125 127 COOper, Edwin L. 1951. Validation of the use of scales of brook trout, salvelinus fontinalis, for age determination. Copeia, 1951, No. 2, June 8, 1951. pp 141- 147. Creaser, Charles W. 1926. The structure and growth of the scales of fishes in relation to the interpretation of their life- history, with special reference to the sunfish Eupomotisggibbosus. Misc. Publ. Mus. 2001., Un. Mich., 17; 82 pp. Deason, H.J. 1933. 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No. 10, issued Sept. 14, 1932) pp 293-398. 128 Fletcher, Alan M. 1957. A rare darter-Spawning. The Aquarium. Vol. XXVI Mdy; NO. 5. P 202. Forbes , Stephen a. 1880. The food of the darters. amer. Nat. 14; 697-703. 1909. on the general and interior distribution of 111- inois fishes. Bulletin of the Illinois state Lab. of Natural History, Vol. VIII, Feb. 1909, article 111. F‘ orb es and Richard son 1920. The fishes of Illinois, second edition. Nat. Hist. Surv. £11., Vol. 3, Figs. 1-76. Many col. p1ts.; atlas, 103 maps. Gosline, Wat. 1947. some meristic characters in a population of the fish, Poecilichthys exilis; their variation and correlation. Occ. Pap. Mus. Zool. Univ. Michigan No. 500; 1-23. Hankinson, T.L. 1908. A,biOlOQiCdl survey of Walnut Lake, Mich. State BOard of Geol. Survey of Mich. 1907 report, pp 157-288. B1. 63. 1919. Notes on life-histories of Illinois fish. Trans. Illinois State Reademy Sci., 12:123—150. 1931. ObserVations on the breeding habits and behavior of fishes in southern Michigan. Pap. Mich. Acad. Sci., Arts, and Letters (1931) 15: 411-425. Heimb urger, H.V. .1913. The factors that determine the distribution of Boleosoma nigrum in Douglas Lake, Cheboygan County, Mich. Rept. Mich. Acad. Sci. (15);120. H119. R. and Jobes, raw. 11940. Age, growth, and production of the yellow perch, Perca flavescens (Hitchill), of Saginaw Bay. Trans. Amer. Fish Soc. 70; 102-122. 129 Hubbs, Carl L. and Lagler, Karl F. 1949. Fishes of the Great Lakes region. Cranbrook Institute of Science. Bulletin No. 26. Hunter, George W. 111 and Rankin, John S. Jr. 1939. The food of picxerel. Copeia, 1939, No. 4, pp 194-199, fig. 1-3 Jaffa, Bertram B. 1917. Notes on the breeding and incubation periods of the Iowa darters,‘§theostoma iowae (Jordan and Meek). Copeia 47: 71-72. Jewell, Minna E. and Brown, Harold W. 1929. Studies on northern Michigan bog lakes. Ecology Vol. X, No. 4, Oct. 1929. Jobes, F.W. 1933. Preliminary report on the age and growth of yellow perch, Perca flavescens (Mitchill) from Lake Erie as determined from a study of its sCales. Pap. Mich. Acad. Sci., arts, and Letters 17; 643-652. Jordan, D.S. and Copeland, H.E. 1876. Johnny darters. The Amer. Nat. 10:335-341. Figs 3. Jordan, Evermann, and Clark 1955. Check list of the fishes and fishlike vertebrates of north and middle America north of the northern boundary of Venezuela and Colombia. U.S. Dept. of the Interior. Appendix X to the Report of the U.s. Commissioner of Fisheries for 1928. Kidd, Patience Ellis 1927. The food of Minnesota fishes with Special refer- ence to the algae. Trans. Am. Fish. Soc. Vol. 57. Lachner, Em. and Westlake, E.F. and Handwerk, P.S. 1950. studies on the biology of some percid fishes from western PennsylVania. The Amer. Midl. Nat. 43(1): 93-111e 1.3.3181“. Karl Fe 1947. Lapidological studies. 1. Scale characters of the families of great lake fishes. Trans. of the ‘ American Micros. Society, Vol LXVI, No. 2, April 1947. pp 154. 130 1956. Freshwater Fishery Biology. Wm. C. Brown 00. Publishers. Dubuque, Iowa. W.’ CeTe 1936. The life history of the fan-tailed darter, gatonotus flabellaris flabellaris (Rafinesque). The Amer. nidl. Nat. 1725): 816-830. Larimore, R.w., Pickering. Q.H., and Durham, L. 1952. an inventory of the fishes of Jordan Creek, Vermillion county, Illinois. State of Ill. Dept. of Registration and Education. Natural History survey Division. BiOIOgical Notes No. 29, Utb‘m. Ill. noenkhaus,‘I.J. 1898. material for the study of the variation of gtheo- stoma caprodes (Rafinesque) in Turkey Lake and Tippecanoe Lake. Proc. Indiana acad. Sci. 7:207-228. Pearse, A.S. 1921. The distribution and food of the fishes of three Iisconsin lakes in summer. Univ. of wis. Studies in Science, Number 3. Madison, 1921. Petravicz , J .J. 1936. The breeding habits of the least darter, Hiero- perca.punctulata. (Putnam) Copeia, No. 2:77-82. .Petravicz, Walter P. 1938. The breeding habits of the black-sided darter, ugadropterus maculatus. cepeia 1:40-44. Prescott, 0.1. 1951. Algae of the western Great Lakes area. Cranbrook Institute of Science. Bulletin No.31. ‘ Raney. 52.0. and Lachner, E.A. 1939. observations on the life history of the spotted darter, ggecilichtgys maculatus (Kirtland) Copeia No. 3; 157-165. .1942. studies of the summer food, growth, and movements of young yellow pike perch, Stizostedios v. vitreum in Oneida Lake, N.Y. Journ. Wildlife Hanagement, Vol. 6, No. 1, pp 1-16. ”WE—... if -—v _ 131 1943. Age and growth of Johnny darters, Boleosoma olmstedi (Storer) and Boleosoma longimanum (Jordan). The Amer. Mid1.Nat. 29(1): 229-238. Reeves, C.D. 1907. The breeding habits of the rainbow darter. (Etheostoma caeruleum Storer), a study in sexual selection. Biol. Bull. 14(1):35-59. Reighard. Je 1913. The breeding habits of the log-perch (Percina caprodes). lich. acad. Sci. 15th Rept.: 104-105. Schneberger, Edward 1930. Growth of the yellow perch (Perca flavescens Mitchill) in Nebish, Silver,fi and Weber Lakes, vilas county, wis. Trans. misc. Acad. Sci., Arts, and Letters 29:103-130. Seal, w.P. 1892. ObserVations on the aquaria of the United States fish commission at Central Station,‘washington, D.C. Bull. U.S. Fish Comm. (1890)10:1-12. shetter, David S. 1936. shrinkage of trout at death and on preservation. Ichthyological Notes. Cepeia, No.1, Hay 10, 1936. snedecor, c.w. 1946. Statistical methods applied to experiments in agriculture and biology. Collegiate Press. Ames, Iowa, 1946. starrett, William C. 1950. Distribution of the fishes of Boone County, Iowa, with special reference to the minnows and darters. American Midi. Nat. 45(1): 112-127. stone, F.L. 1947. Notes on two darters on the genus Boleosoma. COpeia, No. 2; 92-96. Strawn, Kirk, and Hubbs, Clark 1956. observations on stripping small fishes for experi- mental purposes.- Copeia 1956, No.2, May 29, pp 114. 132 Theroux, Frank 8., Eldridge, Edward F., Mallmann, W.L. 1943. Laboratory manual for chemiCal and bacterial analysis of water and sewage. McGraw-Hill, New York. ‘Vasicleave, Harley J., and Mueller, Justus F. 1934. A biological and ecologiCal survey of the worm parasites. Bull. N.Y.St. Coll. Forestry, Syra- cuse U., Vol. LV, No. 3d (Roosevelt‘fiild Life annals V01. 3, No. 1). pp 161-334, pls. 1-40. Van Oostan, John 1929. Life history of the Lake Herring of Lake Huron, as revealed by its scales, with a critique of the scale method. U.S.Bureau of Fisheries, Document No. 1053, pp 276-279. Walch, Paul S. 1948. LimnologiCal methods. The Blakiston Co., Philadelphia. 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