“r004: s1: :3 m: Tifffiiiif FISHES FROM mam" v 6.4163 4 pg}! h ‘4‘." BLUE- ECELL (LEE’UFM rfl§*flfl{ £133), ERALSSY I’AENNOEV [E'E‘Ebfi§1“§u: hgnk van?) mm Nflmzigmq ELACKNGSE SHE?" E. ([le “5335 ‘WWWWI-mk'.” “GE-3mm" 31".} “manna-”:31” Thesis far {he Deg?“ 0f ’3‘- u'ih 2': mmmm c ATE. (mi; A. Ra £25 TEE? ha. 5s. "2“: ECHO“? ...\.". . . 0-169 |\||II||||||II!||I\||I|I||||!|I||| ' 3 1293 10490 956 This is to certify that the thesis entitled “Food studies of three fishes from Northern Michigan ponds, bluegill (Lepomis machrochirus), brassy minnow (lognathus hankinsoni) and northern blacknose shiner (Notrogis hot erolepis ) " presentefi‘bg Jack Ransbottom has been accepted towards fulfillment of the requirements for M. S. in 20010.33r degree filmy-T671 Major professor Date “aI'Ch 10, 1952. -- .Fw—r" -—«-—- v n A ---._ "FOOD STUDIES OF THREE FISHES PROM hORTHERN MICHIGAN PONDS, BLUEGILL (Lepgmis macrochirus), BRASSY MINMOW (gybOgnathus hankinsoni) AND NORTHERN BLACKNOSE SHIEER (Notropis heterolepis)." By Jack A. Eansbottom A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1951 THESES ¥////53; (a; L/ ACKNOWLEDGMENTS The author extends sincere gratitude to Dr. Peter I. Tack for assistance given throughout this investigation and to Dr. Robert C. Ball who made available his library at all times. 5311584 TABLE OF CONTENTS PAGE IETRODUCTION . . . . . . . . . . . . . . . . . . . . . DESCRIPTION OF POND "A" AND RESERVOIR . . . . . . . . ETERODS AND PROCEDURE . . . . . . . . . . . . . . . . Collection of specimens . . . . . . . . . . . . . . Laboratory procedure . . . . . . . . . . . . . . . (Odd-(101 THE BLUEGILL . . . . . . . . . . . . . . . . . . . . . Literature survey . . . . . . . . . . . . . . . . . lO Tood analysis . . . . . . . . . . . . . . . . . . . 13 Discussion of Table I . . . . . . . . . . . . . . . 17 THE NORTHERN BLACKROSE SEINER . . . . . . . . . . . . 19 Description . . . . . . . . . . . . . . . . . . . . 21 Distribution . . . . . . . . . . . . . . . . . . . 21 Literature survey . . . . . . . . . . . . . . . . . 22 Food analysis . . . . . . . . . . . . . . . . . . . 25 Discussion of Table II . . .'. . . . . . . . . . . 29 THE BRASSY Mihh W . . . . . . . . . . . . . . . . . . 54 Description . . . . . . . . . . . . . . . . . . . . 34 Distribution . . . . . . . . . . . . . . . . . . . 35 Literature survey . . . . . . . . . . . . . . . . . 58 Food analysis . . . . . . . . . . . . . . . . . . . 41 DiscuSSion Of Table III 0 O O O O O O O O O O C O O 45 S I: :IITJARY o o O The Bluegill The northern blacknose Shiner (Table of Contents The Brassy minnow . General . . BIBLIOGRAPHY . continued) PAGE TABLE I. II. III. LIST OF TABLES PAGE Stomach and Intestinal Contents of 92 Bluegills 16 Stomach and Intestinal Contents of 56 Northern Blacknose Shiners . . . . . . . . . . . . . . . 27 Stomach and Intestinal Contents of 48 Brassy I'I'Ii n n CV! S o o o o o o o o o o o o o o o o o o o o 4 5 PLATE II. III. LIST OF PLATES PAGE A Map of the Michigan State College; Lake City, Michigan, Experiment Station Reservoir and Experimental Ponds . . . . . . . . . . . . 4 Blacknose Shiner Minnow Figure 1. Drawing of Exposed Gill Chamber to Show Stubby Gill Bakers . . . 52 Figure 2. Drawing of Pharyngeal Arches to Show Terminal Hook . . . . . 32 Brassy Minnow Figure 3. Drawing of Exposed Gill Chamber to Show Short Gill Rakers . . . 57 Figure 4. Drawing of Pharyngeal Arches to Show Teeth With Plat Grinding Surfaces . . . . . . . . . . . . 57 INTRODUCTION The food studies conducted on the three species of fish presented here represent a part of a long-range research problem constructed by Dr. Peter I. Tack, Head of the Depart- ment of Fisheries and Wildlife of Michigan State College. That problem concerns effects, direct and indirect, of ferti- lization of small ponds upon the aquatic environment and its population. This report will contribute to that original problem as a presentation of data collected from control ponds or unfertilized water and indicate what foods the fishes might normally take in their natural environment. Couey (1935), Forbes (1883), Pearse (1915-16) and Reig- hard (1915) contributed much to the understanding of the food habits of the Common bluegill (Lepomis macrochirus) and have presented some results of the earlier work that was done in this country on the feeding habits of fish. Their contri- butions have possibly laid the groundwork for fertilization experiments and the accompanying food studies on Bluegills. Since the Bluegill is a popular sport fish and common in most of our ponds, lakes and streams it received much atten- tion. As a prolific and easily propagated pond fish it has entered into the fertilization experiments on farm ponds that have received so much publicity in recent years (Howell, Swingle and Smith 1941, P. I. Tack 1946, Patriarche and Ball 1949). Much of this work was done in an effort to learn if fertilization caused an increase in the amounts of phyto- plankton and zooplankton present in ponds. The food analyses were conducted on the fish present so as to ascertain if phytoplankton and zooplankton as well as invertebrate animals were being utilized by the fish.with a subsequent increase in their size and weight. The minnows of our inland lakes and streams have been seined and trapped so that their numbers have been seriously diminished. It is widely believed that the seining and trap- ping of these fish is a direct cause of a decrease in the food supply of our game fishes. For this reason restrictive laws have been passed by many states preventing indiscriminate har- vesting of these important forage fish by commercial bait dealers. Recently there has been much experimentation by the state departments of conservation of Michigan, Minnesota, Wisconsin and Ohio with the propagation of minnows in an effort to find species that can be easily reared for bait and forage in small ponds. With the great increase in fishing pressure that has come with the postwar years it is evident that more re- strictive laws will be passed and there is a definite need for more biological studies on possible bait and forage species that can be recommended to the bait dealers. 3:8 maeamfiammam a: anmeam 302.3% mafifimamxm .2350? £63 8M3 “Romance meaem 7231.55 mama so main is H mefim gzoaumagmmm 75:23.» FZMZEMQXM >._._U mxj Hum-300 mFde 26.10.} DESCRIPTION OF POND A AND RESERVOIR Plate I (page 4) is a map showing the experimental ponds and the reservoir located on property of the Michigan State College Experiment Station. The experiment station is lo- cated in Missaukee County of northern Michigan just a few miles south of Lake City. Mosquito Creek arises from subsurface waters in the northwestern portion and flows in a southeasterly direction through the college property. During 1944 this creek was dammed near its upper end forming the reservoir which supplies a head of water for the four experimental ponds. The ponds lie on the downstream side of the reservoir and can be indi- vidually drained or filled. The reservoir is shallow with a muck and peat bottom which overlays a sandy acid soil. The part representing the old creek bed is gravel covered with organic debris. The bottom is littered with many stumps and fallen trees. The shallow shore areas are well covered with emergent vegetation, most of which is alder, dead and alive. At the time of col- lection of the Bluegill specimens, huge beds of Potamogeton grew in the shallows and bordering a bed of Chg3§_in the northwest end. Water smartweed also grew at that end on the north side and much filamentous algae was observed on the bottom in most places. The entire bottom then appeared silted which was in part due to drainage received from the high fields to the south. The reservoir with its snore vegetation gives the appear— ance of a typical bog swamp. It is shallow with a maximum depth of approximately eight feet. It is from this water that the Bluegills were collected. The minnow species were collected from Pond "A". This pond was constructed over sandy acid soil that was previ- ously covered with a layer of muck. The muck was removed. The sandy soil was scooped out and with fill that was brought in formed the sides of the pond. The bottom of Pond "A" is sand except for a few square yards of gravel at one end. It was covered with a heavy layer of plant ooze. This ooze was formed from mats of con- jugating Spirogyra which floated upon one third of the pond's surface in August (Schmid 1949). Decaying Chggg contributed to a lesser extent to the amount of ooze present. It is be- lieved that the mats of Spirogyra shaded out the Chggg and caused it to quickly decay. The ooze formed by this decaying algae was observed to be a foot thick when the pond was drained in April, 1949 (Schmid/l949). Ponds "A" and "b" were drained April 22, 1949. On April 25d, they were filled and 20 adult Bluegills were put in Pond "A" and 21 in "B". On May 5, 1949 when Pond "F" was being lowered, hundreds of minnows came up below the outlet of that pond. Pond "A" is subject to direct contamination by fish fry from the outlet of the reservoir (Plate I). It is from 7 these sources that the Blacknose shiner and Drassy minnow fry originally entered Pond "A". Several schools of minnows were observed in "A" on May 27, 1949. Pond "A", a control pond, has never been fertilized. No fish other than the Bluegills have been introduced into it. METHODS AND PROCEDURE Collection of Specimens All of the young Bluegill and minnow specimens were glass-trapped. Their capture was successful without putting bait or decoys in the traps. The fish upon removal from the traps were immediately placed in jars containing ten per cent formaldehyde. The Bluegills were trapped in open spaces of the Chgrg bed at the northwest end of the reservoir, the traps often being placed on a submerged stump or log. In capturing the brassy minnows and blacknose shiner minnows, the glass traps were placed on the sandy bottom near the sides of Pond "A". Laboratory Procedure hany stomachs were found to be empty due to digestion and regurgitation so it was decided that the contents of the intes- tines would also be included in the food analyses. 8 After being measured for total and standard lengths the fish were dissected and the entire digestive tracts carefully removed and each placed in a vial containing four per cent formaldehyde. A proper label was assigned each digestive tract until future examination. The contents of a vial were later emptied onto a petri plate. Water was added and the stomach and intestines were cut open lengthwise. This necessitated much time and care being spent on the long coiled intestines of the Brassy min- nows. Attention was given miuzous which sometimes enveloped organisms and debris and a probe was used to separate the latter. Analyses were performed by examination with a dissecting microscope. Examination of the Bluegill and Blacknose shiner stomach contents was made with fifteen power magnification while forty magnifications were used for identification of minute specimens. Examination of the Brassy minnow intes- tinal tracts required constant use of forty diameters magni- fication and the presence or absence of_the smaller nonfila- mentous algae was confirmed by examining five or six random samples taken from each digestive tract. This latter examin- ation, under one hundred and fifty power and higher magnifi- cation, was made to learn if Diatoms or other nonfilamentous algae were being utilized to any appreciable extent. A11 identifiable organisms were counted and recorded. For partially digested organisms, care was exercised so as to eliminate the counting of other members from the same body. THE BLUEGILL The Bluegill (Lepomis macrochirus macrochirus) is easily propagated and its habits adapt it especially to cultivation in ponds (Howell, Swingle and Smith 1941). It is easily caught by the angler at all times of the year and its firm flesh proves delicious when properly cooked. It grows quite rapidly and finds suitable habitat plentiful. For these reasons the Bluegill has received much attention in fertili- zation experiments. There is some speculation as to whether the food a fish eats depends more upon its availability and its size or upon an actual preference exercised by the fish. Hess and Swartz (1940) emphasize the importance of preference in their sug- gested "forage ratio". The latter is a ratio of the percen- tage of occurrence of an organism in a population to the per- centage of occurrence in the fish's stomach. In accordance with its difference from one, this ratio suggests that the difference is due to either availability or preference. It does not, however, consider availability in relation to fish so much as it does to the sampling device of the investigator. 10 Literature Survey By use of the "forage ratiofi,Patriarche and ball (1949) established an actual preference for midge larvae by young— of-the-year Bluegills. They found midges to be a staple in the diet of Bluegills taken from four small ponds. Howell, Swingle and Smith (1941) concluded that for Blue- gills weighing over one ounce, midge larvae and pupae were the most important food in Alabama lakes and ponds. They suggest that these fish resort to vegetable food only when the animal food is not available or denied them by reason of competition. Studies by Forbes (1885) and Reighard (1915) indicated this. and they reasoned that the vegetation was not taken acciden- tally by the Bluegill. McCormick (1940) in a study on 100 bluegills collected from Reelfoot Lake, Tennesee found fifty two per cent of the food by volume was plant material, mostly Ceratophyllum and thirty four per cent by volume was Chiron- omid larvae. Rice (1941) examining eighteen Bluegills of an average length of one hundred fifty millimeters found forty per cent was plant material consisting of filamentous algae and duckweed. Leonard (1940) collected forty two bluegills in one day and separated them into size groups. Plankton, small mayfly nympths and Chironomids were the exclusive diet of nine speci- mens with an average standard length of 21.8 millimeters. Plankton, Chironomids and aphids bulked about the same in the 11 diet of fifteen specimens with an average standard length of 40.4 millimeters but Odonata were almost as abundant. This group also took terrestial insects in small numbers and he concluded that they probably fed more on the surface at this length. Eighteen of his specimens with an average standard length of 117.8 millimeters fed almost exclusively on dragon- fly nymphs. Vegetation did not figure in the diet of these fish nor did water mites (gydracarina). Howell (1942) collected twenty Bluegills, all over ninety one millimeters in length, from an unfertilized pond and found the plant £3153 to represent the greatest volume of the food in 40 per cent of the stomachs. The Najas was present in 70 per cent cf the stomachs. Midge larvae ranked first by volume in 50 per cent of the stomachs. gydracarina were found in 10 per cent of all stomachs. Thirty-three Blue- gills, ninety one to one hundred fourteen millimeters long collected from a fertilized pond had fed predominately on insect larvae. These specimens, however, were collected at four different periods from June through November and the specimens collected in June when insects were abundant con- tained predominately insect larvae and vegetation did not represent a major portion of their diet. Couey (1935) reported insects to be the predominate food of small Bluegills with chironomid larvae constituting l2 twenty one per cent of the total. The insect food decreased in the contents of the medium size group and was again in- creased in the larger specimens. Plant food represented thirty four per cent of eighty two specimens ranging from ninety to one hundred forty millimeters in length. This was true for specimens collected from one lake and two hundred thirty three bluegills taken from two other lakes had eaten no plant food and their contents showed 49.5 per cent in- sects and twenty per cent dhironomid larvae. Ewers and Boesel (1935) reporting on fifty three Blue- gills, total length range of twenty one to thirty seven millimeters, taken from Buckeye Lake, Ohio, found Crusta- ceans constituting 86.2 per cent of the total contents. The percentage of Crustaceans was equally divided between Clad- ocera and Copepoda. They reported that the fish fed largely on small Crustaceans. Hyallela represented 14.5 per cent and insects 12.2 per cent of the total volume. Bennett (1948) found Cladocera and Chironomid larvae to be the staple diet of Bluegills of all sizes with Clado- cera forming a large percentage of the stomach contents during the spring and fall. It is during these seasons that Cladocerans reach a peak in deep lakes. He reported only a trace of Hydracarina for one year. Tanner and Ball (1951) reported midge and mayfly larvae by numbers and volume to constitute the major diet of twenty 13 eight adult Bluegills taken from North Twin Lake in northern Michigan. Aquatic plants made up 20.2 per cent of the con- tents by volume, Hydracarina 8.3 per cent by numbers and two per cent by volume. Food Analysis The contents as found in the stomachs of ninety two Bluegills are presented in Table I on page 16. These fish ranged in total length from thirty eight to sixty one milli- meters, averaging 50.4 millimeters. One hundred digestive tracts were originally examined, eight were found to be empty and were not included in the tabulations. Crustaceans constituted 55.9 per cent of the total num- ber of organisms and insects 33.1 per cent. Cladocerans were observed to be the most abundant of all organisms forming approximately My four per cent of the total number. Copepods numbered one hundred twelve and com- prised twelve per cent of the total number of organisms. Ostracods formed 8.6 per cent of the total. 0f the Mala- costraca, only thirteen Amphipods were found. Chironomid larvae comprised almost the entire per- centage of insects found and formed 28.3 per cent of all organisms. The next highest number of insects found were Trichoptera larvae (microcaddis) which formed only 2.3 per cezrt of the total number of organisms. Zygoptera naiads 14 were found in nine digestive tracts and constituted 1.3 per cent of all organisms. The mayfly naiads were not readily available and only one was found. All other insects, mature or immature, were insignificant in number. Water mites (fiydracarina) were found in number to repre- sent 10.5 per cent of all organisms. Like the Chironomdds, the water mites seem to prefer a muck bottom with vegetation. Ninety eight were found in thirty six stomachs. The higher aquatic vegetation listed represented small stem and leaf parts and represented a negligible volume appearing in significant amounts in only a few stomachs. It could be considered decayed vegetation taken in by the fish as they searched for midge larvae or mites in the bottom debris. This accidental ingestion also probably accounts for the inorganic debris found which consisted for the most part of small crystals of sand. The filamentous algae were principally Oedogpnium, Spirogyra and some Ulothrix, and always constituted an in- significant part of the total contents of any one stomach. The terrestial vegetation recorded consisted entirely of the lemmas of reed canary grass which grew in abundance along the shores of the reservoir. They were found in nine stomachs and might have been ingested by the fish as possible insect naiads. The Coleoptera and Hemiptera were digested beyond iden- mesa .H mmnzmaamm azaeHmoHs .weHo amen «acueeem ezmaHmamxm memnqoo mesem z Hwfiaummaaoe ’S.UI1$ I’))"’*l‘l\f" ‘z>l‘ m>.© III.) )0) 17 tification except for one water boatman (Corixidae). The nonfilamentous algae were chiefly Diatoms and Des- :mids and were found to be quite scarce in numbers. ~Discussion of Table I Stomach analyses conducted on the fingerling Bluegills revealed that Entomostracans and Chironomid larvae were the Inain staples of their diet. Together they represent 82.9 per (went of the total number of organisms taken by the ninety two Ifiishu Scuds (Amphipods) represented only a small number of tile crustaceans taken and only 1.5 per cent of the total num- bexr of organisms. The latter represent a subclass (Malaco- stxraca), the larger-sized crustaceans and those observed were C(Dnsidered individuals of a small size. The Cladocerans and Ctlironomid larvae were all small-sized individuals. Higher aquatic vegetation and algae appeared only in \nsry small quantities indicating that these fish were not :Selecting plant items for food. This latter evidence is sup- IDorted by reports on earlier studies conducted by Leonard (1940), Ewers and Boesel (1935), Moffet and Hunt (1942) and lbennett (1948). These investigators found Cladocerans and (Ihironomid larvae represented staples in the diet of small bluegills. All insects, other than the Chironomids, were found only in small numbers. The Trichoptera were the small microcaddis 18 larvae and represented the greatest number, twenty one indi- viduals being found in fourteen stomachs. These adult insects were food organisms of a size too large for the fingerling Bluegills. The mayfly naiads (Ephemeridae) were evidently not available for the fish. hydracarina were taken in numbers by these small blue- gills and the study indicates that those Bluegills in an en- vironment favoring the water mites, might choose these organ- isms as a relatively important part of the diet. The latter are found in abundance in water of a moderate depth with con— siderable plant growth. Tanner (1950) reported that water mites represented 8.5 per cent by number of the total organ- isms taken by twenty eight adult Bluegills. The Bluegills of this study were collected from an en- vironment that definitely favored an abundance of water mites and midge larvae. The midge is more likely to be taken by Bluegills of different environments due to its cosmopolitan range, distribution and abundance. It is generally found in great numbers in most fresh waters. An interesting result of this study was the small num— ber of scuds, Amphipoda, taken by these fish. Other studies by Ewers and Boesel (1955), ball and Tanner (1951) and Leonard (1940) reveal similiar results. A review of the previous studies did not reveal that fingerling Bluegills were taking vegetation, higher aquatic 19 or algal, as a consistent part of their diet. Those investi- gators finding vegetation representing a considerable per cent of the contents (Couey 1955, Howell 1942, Rice 1941, and McCormick 1940) were examining specimens all of a longer length (over ninety millimeters) than those collected for this study. There appears to be quite some variation in the staple organisms taken by different size groups listed by investi- gators in the past but the above remarks pertain to all re- viewed for this paper. Table I indicates that the Bluegill fry soon after hatching subsist mainly on zooplankton but sufficient bottom dwellers were found so that the diet must certainly reflect the population of bottom fauna. It seems to indicate that size and structure of the organisms are limiting factors for fingerling bluegills. THE NORTHERN BLACKNOSE SHIRER Minnows are an important link in the chain of food pro- duction of most waters. They are small fishes never reaching a size that allows them to seriously prey on game species. They represent natural forage for the game species and draw attention away from the fry of the latter. They compete with the latter for food organisms, mainly Crustaceans. It is be- lieved that their numbers have been diminished in our lakes, 20 streams and ponds through harvesting by bait dealers. In a search for possible bait species much attention has been given their propagation in ponds. It seems particular attention should be given those species that are vegetable feeders or "bottom ooze" feeders assuming that they will offer little competition to the game fish. Also, it seems advises- ble that the species should be prolific, spawning late and in numbers so great as not to be easily depleted by predators, game fish or others. The vegetable feeder would probably re- quire less attention in the matter of feeding and selection of a pond. The horthern fathead minnow, mainly a vegetable or "bot- tom ooze" feeder,has proved to be an excellent bait and forage fish easily reared in small ponds. Attention was also given the Eastern silvery minnow (gybognathus nuchalis regius) with successful propagation in a pond devoid of vegetation (Raney 1941). The Bluntnose minnow (hyborhynchus notatus) with feeding and breeding habits quite similiar to the Fathead minnow (Pimephales promelas) has also proved to be an ideal minnow for propagation in small ponds. The Bluntnose and Pathead minnows are not strictly "bottom ooze" feeders as is the Eastern silvery minnow which belongs to the same genus as the Erassy minnow (Hybognathus hankinsoni). Little is known of the habits of the brassy minnow and Raney's success with the Silvery minnow has probably directed attention to 21 its possibilities. The Northern blacknose shiner (Notropis heterolepis heterolepis) has received little attention concerning its feeding habits. It has not been considered a possible bait species because it is not hardy enough to withstand long- distance hauling by truck or the close confinement of the min- now pail. In its natural environment it is a competitor or ”weed species" and offers forage for the larger predators. Everman (1901) reported that the Blackness shiner was quite effective as a bait for Yellow perch and that some anglers found the larger ones very good for small Largemouth black bass. He mentioned that for Yellow perch there is no better minnow if the larger ones are selected. Description It is a rather small minnow reaching a length of a little over two inches. It is slender with a dark lateral band ex- tending over the snout. Black spots bordering the lateral line pores converge ventrallyto form cresent-shaped bars. Distribution Hubbs and Lagler (1947) reported that the Blacknose shiner was found in the waters of southern Canada from Saskatchewan eastward, including part of the Hudson Bay drainage; south to 22 Maine, New Hampshire and the Lake Champlain basin; to the head- waters of the Hudson and Susquehanna systems in New York and of the Ohio basin in new York and Pennsylvania. It extended westward to Iowa and North Dakota and was represented south- ward in the Mississippi Valley by another subspecies. It is found throughout the Great Lakes region its characteristic habitat being weedy glacial lakes and connecting streams. Literature Survey Little has been written of the feeding habits of the Northern blacknose shiner consequently information concerning shiner minnows of the same genus with a similiar range of dis— tribution has been borrowed from the literature. Also in the past, the Blacknose shiner (Notropis heterolepis) and the Bridled shiner (Notropis bifrenatus) have been confused when they occurred in the same water and some information sup- posedly pertaining to the Blacknose shiner has been disre- garded. Hankinson (1920) reported that the alimentary tracts of Michigan blacknose shiners contained Entomostraca, insects, filamentous algae and Diatoms. Forbes (1885) concluded that young Cyprinidae drew almost indiscriminately for their food supply upon protozoa, algae and Entomostraca. Ewers (1935) examined the stomachs of fifty eight Lake 23 emerald shiners (Notropis atherinoides) averaging 61.3 milli- meters total length and found Crustacea to constitute 66.7 per cent by volume (Copepoda 29.5 and Cladocera 37.5 per cent) and insects making up 12.4 per cent with midge larvae predo- minating among the insects. Boesel (1957) reported that sixty Mimic shiner stomachs (kOtropis y; volucellus) contained 54.6 per cent by volume of mayfly naiads, midge pupae and adults while Crustaceans con- stituted 25.2 per cent with Entomostraca being abundant. These fish averaged 45.8 millimeters total length and ranged from twenty nine to seventy one millimeters. It was observed that the contents of the larger fish were mainly insects and those of the smaller were entirely Crustaceans. There was no evi- dence of a progression in this direction relating to the in- creased size of the fish. I In this same study, stomach contents of thirty seven Northern sand shiners (Notropis deliciosus stramineus) were examined and Crustaceans were found to be inconspicuous. The contents were in poor condition and debris was classed as sixty per cent of the total volume but insects made up most of the organisms found (35.5 per cent) and midge pupae and larvae were abundant. ho vegetation was found other than a trace of algae in two stomachs. The contents of one hundred ten Spottail minnows (Notropis hudsonius) with total lengths ranging from nineteen to eighty seven millimeters were studied. 24 It was found that these fish had fed on different animals in different evnironments and the specific type of food did not vary regularly with the size of the fish. Cladocerans and in- sects (Diptera predominating) were equal in volume and com- prised seventy five per cent of the total. Concerning Shiners in the Des Moines River, Starrett (1950) mentioned that the Spotfin shiner, Central bigmouth shiner (Notropis d;_dorsalis), herthern common shiner (fig; tropis cornutus dorsalis) and the Rosyface shiner (Notropis rubellus) tend to feed at or near the surface more than most of the Shiners commonly found in the river. The genus No- tropis (Notropis deliciosus excepted) were classed as semi- specialized feeders and all drew heavily on insect larvae and adults throughout the four seasons. He did not list Crustacea in his tables but mentioned that the Central bigmouth shiner showed more of a preference for Entomostraca than any of the other minnows and fed occasionally on phytoplankton during the summer. However, the scarcity of Entomostraca and midge larvae in the river was recognized and Starrett considered that scarcity to be a limiting factor for some minnows. Forbes and Richardson (1920) and Hubbs and Cooper (1936) in their investigations on minnows attempted to relate the feeding habits to the morphological adaptations of the fish. Forbes and Richardson (1920) mentioned that few and short gill rakers were characteristic of the mud-eating minnows. They 25 also mention that fishes as small as the minnows do not need specially developed gill rakers, since the gill arches them- selves are so small and the spaces between them so small that any object large enough for food would not go out through the gills with the respiratory current. However, they also men- tion that the Golden shiner (Notemegonis crysoleucas), and the Blackchin shiner (Notropis heterodon) took large numbers of Entomostraca and would make them their sole food in ponds where the latter were abundant. The Golden shiner has long fine gill rakers and those of the Blackchin are unusually developed. These species also have hooked pharyngeal teeth. Reporting on the food of eighteen Blackchin shiners, they mention that it was peculiar in respect to the large percen- tage of Entomostraca included and attribute the fact to the well developed gill rakers and the small size of the fish. Mention was also made of the abundance of small Crustaceans in the waters from which the two species were taken. These fishes, however, showed a varied diet with insect larvae and algae being principal items. Food Analysis The intestinal tracts of forty Elacknose shiner minnows were examined and the contents classified and recorded. The intestinal tracts of four minnows were found to be empty and the percentages presented in Table II (page 27) were tabu- mama .ma mmuoaoo “zaeHmoHa .tho amen “zowaaan Haaaazamxm meeqqoo sheen zaeHmQHa .=<= 220m acme amaomqqoo mmaszn mmoaao nw.H HdeB ¢H.O m.m mm.o ©.m ¢H.O m.m ®@.O b.0H bw.H ®.on mm.wm ¢.¢m mm.mn ¢.¢m am on 0 fi hm ®r40h4 mm mfianoo cansmAOQH manned oaammao coauwpomo> oprswm aonwfin mamas maopnoEmHHMnoz omwae muopnoEmHHm wrimri mom bum os>ama sampmfia omoaoomm meadow owUHEonoaano os>ama omnfisonoafino macaw“: 9.. 955a. snoowapmo spooomwao mwomoaoo wommemowoflmm mEmHnswao ho mamsmfi>aqu gonads Hmpou mo omwpnooaom do owwpnooaom IQOO msmanwwao mnacamp massea>aeea Ho managed mnmficmwao we henna: Hence .EE mn.mn npwsoq Upwpcwpm ommao>¢ .88 .EE no.0m npwnoq Hence ommao>¢ me-mm spaced ewaequm .ss mourn summon fleece mmM£Hflm mnOSMOdqm zmflmamoz *on ho nezfiazoo ddzHHntzH 924 2042083 HH mqnde 28 lated on a basis of thirty six total specimens. The average total length of the specimens was 50.97 millimeters, the range extending from thirty seven to sixty three millimeters. The average standard length was 59.38 millimeters with the range extending from twenty eight to forty nine millimeters. The females were slightly larger than the males with an average total length of 52.5 milli- meters, the latter averaging 50.0 millimeters. The average standard length for each was 40.5 and 38.55 millimeters res- pectfully. Entomostraca constituted amost the entire total of or- ganisms by number, 98.57 per cent. Of this percentage, Cladocera represented 56.84 per cent, Copepoda 39.86 per cent and Ostracoda 1.87 per cent. A Chironomid larvae was found in each of six digestive tracts and one adult was recorded. Two bark lice (Psocidae) were found and one dipterous larvae. All insects, larvae and adults, constituted only 1.43 per cent of the total num- ber of organisms. It was interesting to note that most of the Crustaceans observed in all digestive tracts were much smaller than those found in the tracts of the Bluegills taken from the reservoir and the Brassy minnows taken from Pond "A". Some of the Cope- poda recorded were observed as the nauplius, metanauplius and other early stages. Also many young Cladocerans were recorded. 29 The filamentous algae found in seventy five per cent of the tracts, consisted mostly of Spirogyra with some Oedoco- nium and was observed as abundant in only a few of the speci- mens. It appeared as traces in all other specimens. The nonfilamentous algae found in four specimens were Closterium and Kerismopedium, both appearing only as traces. The higher aquatic vegetation recorded was observed as traces in five specimens. The organic debris listed was most often parts of crus- taceans or their eggs. The contents of the specimens were in poor condition and more difficult to record than those of the other two species. In recording the number of Copepoda it was more or less a matter of matching tails with cara— paces of these small animals. Organic debris was recorded for 83.53 per cent of the specimens but is relatively im- portant only as an indication of the condition of contents. The inorganic debris represents small crystals of sand found in twenty three specimens, 65.89 per cent of all speci- mens 0 Discussion of Table II The food study conducted on the Blacknose shiner minnows from Pond "A" revealed that they subsisted mainly on Ento- mostracans. Insects represented only 1.45 per cent of all organisms found. hone of the literature reviewed for any of 30 the species of hotropis revealed such a high percentage of Crustaceans. There is little information concerning the food of the Llacknose shiner. Forbes and Richardson (1920) reporting on a related species, the Blackchin shiner (Notropis heterodon) reported finding unusual amounts of hntomostraca and mentioned that perhaps the unusual develOpment of the gill rakers ac- counts for this. Aquatic insect larvae, mainly Chironomid, represented the other organisms found in their eighteen speci— mens. The gill rakers of the Blackchin shiner are well-devel- Oped and rather long while those of the Blacknose shiner are short, well-rounded and few in number (Plateifl; Figure l on page 52). It appears that no relationship between the food and the gill rakers exists here. It is interesting to note that the pharyngeal teeth of the Blacknose shiner are hooked or recurved (Plate I, Figure 2 on page 52) as are those of the Blackchin shiner and Golden shiner. It is in these latter species that Forbes and Richardson (1920) reported finding Entomostraca appearing in abundance. It appears that the specimens examined for this study fed almost exclusively on Entomostraca and this is not due to any development of the gill rakers. As for size, this species does compare with the blackchin shiner and this might be a factor in the selection of the food organisms for it was ap- M002 Q no need gouache .moapmoamapqoea weappaanom noapavnoo one omen a mo mEopH* Ill H¢.OH m deodomoo nn.w m «accommao no.m m mmoowaumo ma b©.©a m mz¢m0 on zoae¢emmM> 0HH¢:W&.mmmem woman mb.m© an m¢mQ< mbeezm3 meSUH>HUnH mamanmmao.mnacawp mfimfinmmao yo me coapmfifipmm no ommucooaom ance mamsmfl>fimna Ho Aeneas gonad: Hence .EE m.¢¢ npwnoq cnmmnmun omwno>« .55 $0.00 dawned Hence owmno>¢ HHH mqm¢e .ss om-mn season enaeaapm .ss Hands hemmed Hence EOBBOM mo mHnMH¢z¢ z¢ mzozaHE Mwm¢mfl mv ho weamezoo udzHBmmBzH 93¢ mU