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UNIVERSITY OF 
 
 ILLINOIS LIBRARY 
 AT URBANA-CHAMPAIGN 
 
 
Digitized by the Internet Archive 
 in 2018 with funding from 
 University of Illinois Urbana-Champaign 
 
 https://archive.org/details/biologicalinvestOOforb 
 
IJ713 
 
 7f£ 
 
 i.3 
 
 Tilt LIBRARY 
 OF THE 
 
 UNIVERSITY OF ILLINOIS 
 
 Illinois State Laboratory 
 
 OF 
 
 Natural History 
 
 ■ A 
 
 Urbana, Illinois, U. S. A. v#;- i ■ 
 
 £ * 
 
 * *• 
 
 STEPHEN A. FORBES, Ph.D.; LE.D., 
 
 Director 
 
 BIOLOGICAL INVESTIGATIONS ON THE ILLINOIS RIVER 
 
 1. THE WORK OF THE ILLINOIS BIOLOGICAL STATION 
 
 l 
 
 2. THE INVESTIGATION OF A RIVER SYSTEM IN THE 
 
 INTEREST OF ITS FISHERIES 
 
 BY 
 
 STEPHEN A. FORBES 
 
 1910 
 

 
 % 
 
The person charging this material is re¬ 
 sponsible for its return to the library from 
 which it was withdrawn on or before the 
 Latest Date stamped below. 
 
 Theft, mutilation, and underlining of books 
 are reasons for disciplinary action and may 
 result in dismissal from the University. 
 
 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN 
 
 977 
 
 L161 — 0-1096 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE WORK OF THE ILLINOIS BIOLOGICAL STATION.* 
 
 Under the conviction that the present movement for an inten¬ 
 sive, scientific study of local faunas and floras is likely to grow, 
 and to dominate largely the work of many of our younger biolo¬ 
 gists, and that it will center at first in our universities, but will 
 come to require more or less independent biological stations for its 
 complete realization, I have thought that an outline of the efforts of 
 a few Illinois naturalists to work this field in a systematic manner 
 might be of interest and of advantage, both positive and negative, 
 to the members of this Society. 
 
 The establishment, on the Illinois river sixteen years ago, of a 
 small station devoted to this end was immediately owing to the co¬ 
 incidence of a circumstance and an accident, the circumstance being 
 the existence of a natural history survey of the state, in rather slow 
 and desultory operation at the time, and the accident being- the shift¬ 
 ing of certain courses in zoology at the University of Illinois from 
 one year to another in such a way as to leave the department with 
 much less than the usual amount of teaching to do during the year 
 1894, and with much more time, consequently, for outside work. 
 In view of these conditions and others which it is not necessary to 
 specify, I asked of the trustees of the LIniversity, in March, 1894, 
 an appropriation of fifteen hundred dollars a year, and a further 
 sum of five hundred dollars, to enable me to establish on the Illinois 
 river a permanent biological station for continuous investigation 
 work throughout the year; and in partial compliance with this request, 
 a sum of eighteen hundred dollars was made available for the pur¬ 
 pose. Two weeks after this vote, a station was actually opened at 
 Havana in leased quarters, with a temporary equipment provided by 
 the natural history survey and the University conjointly. As the 
 university appropriation was not available until the first of July, 
 the funds of the natural history survey were drawn upon for the 
 establishment of the work and for its maintenance for the first three 
 months, and the same source of supply was resorted to to meet all 
 deficits on station account up to July 1, 1895. At the biennial legis¬ 
 lative session of 1895 the Illinois legislature made an appropriation 
 of twenty-five hundred dollars for the equipment of the Illinois Bio- 
 
 *Read to the Central Branch of the American Society of Zoologists at Iowa 
 City, AprilJS, 1910. 
 
 1 
 
9 
 
 tmJ 
 
 logical Station (under that designation), and of three thousand dol¬ 
 lars per annum for its expenses. This legislative appropriation for 
 expenses was repeated in 1897 in a bill providing for the mainte¬ 
 nance of the natural history survey, and the work has been continued 
 under these auspices, and with approximately these appropriations, 
 ever since. The station is consequently a state establishment, sup¬ 
 ported wholly from state appropriations, for purposes of investi¬ 
 gation only,—a point in which it differs, I think, from everv other 
 American station of aquatic biology. 
 
 Its general objects, as defined by me in a formal report published 
 in 1894, were to provide additional facilities and resources for the 
 natural history survey of the state; and to contribute to a scientific 
 knowledge of the whole system of life existing in the waters of 
 the state, with a view to economic as well as to educational appli¬ 
 cations. It had for its immediate field the entire system of life in the 
 Illinois river and connected lakes and other adjacent waters; and 
 an intention was expressed to extend operations as rapidly as pos¬ 
 sible to the Mississippi river system, thus making a beginning on a 
 comprehensive work on the general subject of the aquatic life of the 
 Mississippi valley in all its relations, scientific and economic. 
 
 The special subject upon which I fixed at first as the point tow¬ 
 ards which our studies should tend, was the effect produced on 
 aquatic plant and animal life by the periodical overflow and grad¬ 
 ual recession of the waters of great rivers,—a topic chosen es¬ 
 pecially because it had never been studied, and because it included 
 in its scope nearly everything concerning the life of our waters of 
 any considerable interest either to the biologist or to the practical 
 man. As another result of our work I hoped that we should ac¬ 
 cumulate material for a comparison of the chemical and biological 
 conditions of the waters of the Illinois river at that time and after 
 the opening of the Chicago drainage canal, then in process of con¬ 
 struction. 
 
 The main features of the equipment provided, were a floating 
 biological laboratory, built especially for the purpose in 1895, a 
 steam launch, a number of skiffs, a variety of seines, pound-nets, dip- 
 nets, and other fishing apparatus, a plankton equipment, including 
 a centrifuge for the rapid condensation of the minute contents of the 
 collections, and a set of breeding-cages of special construction for 
 keeping aquatic insects under natural conditions but exposed to con¬ 
 tinuous observation. The laboratory boat was amply provided with 
 microscopes, chemicals, glassware, aquaria, and apparatus and ma- 
 
3 
 
 terials for the preservation of specimens and for ordinary micro¬ 
 scopic technic. It was equipped with tables and other essentials 
 for fifteen workers in addition to the station staff. It proved to be 
 admirably adapted to its objects, being as comfortable and satisfac¬ 
 tory a workroom for the investigator as were the regular labora¬ 
 tories of the University. It had, for our purposes, the very great 
 advantage of a thoroughly portable character, and it was repeatedly 
 moved from place to place at Havana, and established for months 
 at a time at various other points on the river. 
 
 Beginning in April, 1894, the work continued at Havana until 
 April, 1899 (five years), at which time it was transferred to Mere- 
 dosia, about forty-five miles down the Illinois. Here it remained 
 until June, 1901 (two years and two months), when it was moved 
 up the Illinois a hundred and sixty-five miles to Ottawa, the high¬ 
 est point on the river which it was possible to reach with our equip¬ 
 ment. After a year and five months at Ottawa, the station equip¬ 
 ment was transferred early in November, 1902, to Peoria for the 
 winter, and in May, 1903, it was removed to Henry, thirty-three 
 miles above. 
 
 After the organization of the Station, the survey of its field, 
 and the selection of substations for continuous work, it remained in 
 charge of Professor Frank Smith for the first fifteen months, after 
 which Dr. C. A. Kofoid was made its superintendent. Resigning 
 to take effect December 31, 1900, Dr. Kofoid was succeeded by Mr. 
 Thomas Large, who was in charge until the fall of 1902, and he was 
 followed by Mr. R. E. Richardson in 1903. 
 
 By the fall of 1903, after more than nine years of active opera¬ 
 tion, our accumulations had so far outrun our systematic studies 
 that a change of program was imperative; and the equipment was 
 laid up at Henry under a caretaker, where it remained out of use, 
 except as loaned to the Chicago Drainage Commission, until the sum¬ 
 mer of 1909. You all remember the Lincoln story of the Sangamon 
 river steamboat, which could make steam enough to run if it didn’t 
 whistle, but could only whistle by ceasing to run. Our biological 
 station has found itself, from time to time, in a similar predica¬ 
 ment. It has not had money enough to maintain active operations 
 in the field and to prepare and publish papers and reports at the 
 same time. So, after a nine years’ run, it beg*an to whistle, and 
 now, having blown its three long* blasts—two on the plankton collec¬ 
 tions and one on the fishes of the state—it has been running again 
 since last July. 
 
4 
 
 The field work of the first two years was comprehensive of all 
 aquatic forms and situations, including plankton collections, quan¬ 
 titative as well as qualitative, shore and marginal collections of 
 mollusks, insects, and crustaceans, dredgings from the bottom at 
 various depths, and collections of fishes and other vertebrates, by 
 means of various kinds of apparatus. The next three years were 
 mainly devoted to plankton work in the Havana district, and the 
 last four, spent mainly at Meredosia, Ottawa, and Henry, to work 
 on the fishes of the Illinois system. During our period of active 
 operation, approximately six thousand collections were made in all, 
 of which five hundred were fishes and two thousand were plankton 
 collections, the remaining thirty-five hundred consisting of insects, 
 mollusks, and a general variety of aquatic and subaquatic forms. Six 
 hundred and forty of the plankton collections were made at Ha¬ 
 vana by strict quantitative methods, and were thus available for a 
 comparative study of the product of various waters at all times of 
 the year. Two hundred and thirty-five of these were from the main 
 stream and four hundred and five from other stations adjacent. 
 
 Besides our purely biological work, weekly samples of waters 
 were regularly examined by chemical methods for three and a half 
 years, under an arrangement with the Water Survey of the state, 
 established in 1895. 
 
 I can not attempt, in this rapid outline, to present even in brief¬ 
 est summary the results of this work, but may be permitted to ab¬ 
 stract a few general statements from its two most important publi¬ 
 cations—the report on the fishes of the state and that on the plank¬ 
 ton collections, the former prepared by Mr. Richardson and myself, 
 and the latter by Dr. Kofoid. 
 
 From our fish collections it appears that the Illinois basin is thor¬ 
 oughly representative of the state at large. Of the hundred and fifty 
 species of Illinois fishes known to us, a hundred and twenty-eight oc¬ 
 cur in the Illinois or its tributaries. Of the twenty-three species not 
 found by us in that basin, eight are excluded by their definitely south¬ 
 ern range, six by their distinctly northern distribution, and four are 
 as definitely western, while the five remaining are so rare in Illinois 
 that they appear in any of our waters only by an unusual chance. 
 About three dozen of the hundred and twenty-eight species in the 
 Illinois basin have a marketable value as food. A dozen of the 
 best species are of really good quality, and half of these are among 
 the best freshwater fishes in the country. 
 
 From our plankton studies it appeared that the average ratio 
 of plankton organisms to the water of the main stream, year in 
 
and year out, was 2.7 parts per million, and the total average amount 
 of plankton moving down stream past Havana reached the astound¬ 
 ing aggregate of three hundred and fifty thousand barrels, or seven¬ 
 ty-five thousand tons, per annum, equal to eight and a half tons per 
 hour the year round. This was about fifteen times the total weight 
 of the fish then taken from the river each year. 
 
 Besides our plankton studies made at the various Havana sta¬ 
 tions, each representative of a characteristic aquatic situation, a 
 beginning has been made in a study of the system of the entire 
 stream, taken as a single unit of environment. For this purpose, 
 trips by steamboat were made for considerable distances, with con¬ 
 tinuous plankton collections throughout each trip. Longitudinal bio¬ 
 logical sections of the stream were thus made, aggregating four 
 hundred and fifty miles for the Illinois river and three hundred and 
 sixteen miles for the Mississippi, from St. Louis to Quincy and re¬ 
 turn. On the first trip, made in May, 1899, an iron pipe delivered 
 a continuous stream of water into a plankton-net which was lifted 
 and emptied every twelve miles. In all the other trips a steam 
 pump was used to supply a continuous current, which was passed 
 through a meter, enabling us to determine precisely the amount of 
 water strained. 
 
 By such studies one gets a vivid idea of the individuality of the 
 river as an organism, and of the complexity of its structure and the 
 sensitiveness of its physiological reactions. A stream like the Illi¬ 
 nois, with its flowing current, varying in rate in different parts of its 
 course, variously fed by streams, by lakes, by marshes, and by under¬ 
 ground springs, temporarily influenced and often profoundly af¬ 
 fected by local storms, by drouth, by floods, is a very different sub¬ 
 ject of study from a lake, and to me a far more interesting one. A 
 lake is sessile, simple, stolid, coelenterate; a river is motile, com¬ 
 plex, sensitive, and articulate: a lake has an aspect, a constitution; 
 but a river has a character, a behavior. The river has also a spe¬ 
 cial attraction to the student of biology in that it is more readily 
 analyzable than a lake, into distinct and largely independent sec¬ 
 tions or situations which can be studied separately and as a series. 
 
 For a discussion of our data of continuous collection, we have 
 divided the Illinois from Hennepin to its mouth, the part patrolled 
 by us, into six sections, each with its well-marked individuality. 
 The slope of the bed, the extent and nature of the bottom-land 
 waters feeding the main stream, the size, length, and number of its 
 tributaries, and the contributions of sewage waste from towns upon 
 
6 
 
 its banks, are the principal causes of differentiation in different parts 
 of its course,—differences which express themselves most vividly in 
 the amount and character of the plankton, but which are reflected 
 also more or less definitely in the general aspect of its biology. 
 
 Since last July our work has been carried forward under the 
 immediate charge of Mr. R. E. Richardson. It has been mainly 
 directed to a comparison of present conditions with those of the 
 period preceding the opening of the drainage canal, and to the col¬ 
 lection of materials for a fuller study of the food of fishes than has 
 hitherto been made and for a comparative study of the contents and the 
 physical and chemical condition of the bottom in several selected 
 situations, as related to differences in the plankton and other bio¬ 
 logical products. From weekly collections, begun August 20 and 
 continued for four months, we learned that the yield of plankton 
 in the main stream per cubic meter was then, at Havana, approximately 
 double that of our earlier period, notwithstanding the fact that the 
 water-level is about three feet higher on an average than it was 
 before the opening of the drainage canal. 
 
 Our main objects for the coming two or three years will be to 
 complete a comparison of present conditions with those of the former 
 time; to study the river as a unit with reference particularly to its 
 economic values, its protection, and its improvement; to work out 
 the details of its biological regimen by a study of the influence of 
 the various conditions affecting the course of events in various sit¬ 
 uations ; and to carry out comparative studies between the Illinois, 
 the Mississippi, and the Missouri—all readily accessible from our 
 location and by means of our equipment. It is a large, a fruitful, 
 and an important field of research, and we invite the cooperation of all 
 so situated as to contribute to our knowledge of any part of it; 
 and to this end investigators will be admitted to our Havana station 
 at any time after June 1. 
 
i 
 
 THE INVESTIGATION OF A RIVER SYSTEM IN THE IN¬ 
 TEREST OF ITS FISHERIES.* 
 
 We have in Illinois a river of the same name as the state, which 
 is in many ways one of the most remarkable streams in the country, 
 and in no respect is it more remarkable than in its natural adapta¬ 
 tion to the breeding and maintenance of a large and varied popula¬ 
 tion of fishes and other useful aquatic animals; in none has it made 
 a more remarkable record than in the supply of fish food which it 
 has produced and is now producing—not for Illinois only, but 
 for the country at large, sending out of the state, as it does, and 
 mainly into eastern cities, much the largest part of its catch. The 
 annual yield of the Illinois river in fishes only is over twenty-four 
 million pounds, worth at wholesale about $738,000. If this annual 
 output were turned into silver dollars, and these were placed in a 
 row, equidistant from each other, along one of the banks of the 
 stream, there would be a dollar every year for every two feet of the 
 river’s course from its origin to its mouth. 
 
 Furthermore, we have no reason to suppose that this stream and 
 its adjacent waters have yet reached their limit of economic yield. 
 The effect produced on them by the opening of the drainage canal 
 from Chicago, and the still greater effect due to the introduction of 
 the European carp, are examples of the fact that the original con¬ 
 dition of the stream may be largely changed for the better, and give 
 us reason to believe that it may be made a still more important as¬ 
 set than now, both for the people of the state and for the general 
 public who are the chief consumers of its product. Evidently this 
 is one of the natural resources of the state and country which should 
 be carefully safeguarded. A thoroughgoing, practical investigation 
 of this stream is now especially imperative because of the great 
 changes in progress at the present time in its environment and the 
 still greater changes contemplated or impending, which have affected, 
 or must certainly affect, greatly and permanently, its value for the 
 purposes which it now serves. Reclamation projects, for the pro¬ 
 tection, drainage, and cultivation of its bottom-lands; manufactur¬ 
 ing projects, threatening a various contamination of its waters; ca¬ 
 nalization projects and projects for the control and equalization of 
 its flow, in the interests of transportation,—all are being earnestly 
 agitated, and several of them are in process of active execution. 
 
 *Read before the American Fisheries Society, New York City, September 
 28, 1910. 
 
8 
 
 Although the problem of the maintenance and development of 
 favorable conditions in this stream is by these facts made somewhat 
 special, in many of its general features the Illinois is virtually like 
 all other rivers, and a satisfactory program for its investigation 
 would be readily adaptable, I believe, to many other streams, and 
 applicable in its main features to rivers in general. It is for these 
 reasons especially that I have ventured to ask the attention of this 
 broadly representative body to my special topic, and to ask your 
 criticism of its proposals now, when criticism can be made most 
 profitable. 
 
 Versed as you are in the literature and accepted methods of fish- 
 culture, I scarcely need remind you that principles of management 
 and methods of protection and improvement are not nearly so well 
 settled for the fisheries of our natural waters as they are for fish- 
 culture in artificial ponds, and that the maintenance and utilization 
 of our fisheries has been much less thoroughly studied for rivers, 
 either in this country or in the Old World, than it has for lakes. 
 This is, no doubt, in part because lake fisheries are, generally speak¬ 
 ing, both more important and more readily controllable than river 
 fisheries, and partly because the river problem is much the more 
 complicated and difficult of the two. The Illinois river has, how¬ 
 ever, so many lakes in its bottom-lands, merged with it in times of 
 flood, distinguished from it successively with the retreat of the 
 overflow, but connected with it and contributing to it at its lowest 
 levels, and the river itself has, as a home for fishes, so many of the 
 characteristics of a lake, that its problems, although complex and 
 difficult, do not compare unfavorably in importance with those of 
 any lake in the world of equal area. Its average fall through the 
 lower four-fifths of its course is only i% inches per mile, and 
 there are stretches of several miles throughout which its fall per 
 mile is only about a quarter of an inch. Its current at low water, 
 as it swings from side to side of its broad and level flood-plain, is 
 as slow, at the dams, as half a mile per hour, and although the mid¬ 
 stream flow at high water is of course much stronger, there are 
 even then extensive backwater shallows in which a fish could hardly 
 tell whether it was swimming upstream or down. 
 
 It is one of the most interesting features of our field of opera¬ 
 tion that we are able to bring easily into comparison the system of 
 life in this sluggish, lake-like stream with that of the swift Missis¬ 
 sippi, into which it flows, or that of the still swifter Missouri, whose 
 mouth is only twenty-four miles from its own. Even the Ohio, very 
 
9 
 
 different physically and biologically from either of the other three, 
 is not beyond our reach, and comparative studies of all these streams 
 have been begun by us this year.* 
 
 In such an investigation as is here proposed, the foundation in¬ 
 quiry which must fix our beginning' points and show where the prin¬ 
 cipal emphasis should at first be placed, is this: Just what is it that 
 we need to know in order that we may be in a position to do all 
 that we might hope to accomplish, and ought to undertake, for the 
 conservation and increase of our aquatic resources? To this in¬ 
 quiry I must make, at first, a general and perhaps a disappointing 
 answer. It is perfectly evident that if we wish to maintain or to 
 improve the conditions of life for the fishes of our rivers, we must 
 first know what the present conditions are, and which of these are 
 the most important to our purpose. We might, it is true, hatch 
 young fish by the million, and throw them out by the hundred thou¬ 
 sand, into all the sorts of waters which their species inhabit, without 
 any precise knowledge on cur part of the conditions in which they 
 will find themselves when set free, or any rational judgment of the 
 chance that they can survive to adult size. This sort of thing, 1 
 surmise, has sometimes been done, but I hope that it is, at any rate, 
 done no longer, and certainly it can no longer be defended as either 
 scientific or practical; it is simply ignorant. Intelligent plans for 
 their improvement require that we should know the conditions under 
 which our fishes live, and that we should be able to distinguish bene¬ 
 ficial conditions from injurious, and important conditions from un¬ 
 important. We need to know what our fishes require in respect to 
 the main essentials of their well-being—that is, to a suitable water 
 supply, to oxygen for respiration, to temperature in the different parts 
 of the year, to their food at all their ages, to breeding places, to 
 freedom of migration and other necessary movements to and fro, and 
 to freedom from injurious physical conditions, from poisonous gases 
 and solutions, from parasites, from diseases, from excessive com¬ 
 petition, especially for food, and from decimation by their enemies 
 
 It is commonly conceded I think, both by scientific students and 
 by practical fishermen, that the most general and rigorous limita¬ 
 tions upon the numbers of fishes are those set by their breeding 
 
 *Plankton collections, continuous for all practical purposes, have now been 
 made from the main streams of these great rivers, aggregating - 1010 miles for 
 the Illinois, 1195 miles for the Mississippi, and 46 miles for the Ohio. On the 
 Illinois river these collections were made, for ninety miles, from the station 
 launch; but for the remainder of this Illinois work, and for all that on the Mis¬ 
 sissippi and the Ohio, we have had the use of the steamer “Illinois,” kindly 
 placed at our disposal for this purpose by the State Fish Commission. 
 
grounds and their food supply, and that of these the latter is the 
 most important. We especially need to know, therefore, what the 
 more valuable fishes feed upon as fry, as young, and when full grown, 
 under various conditions, and at different times of the year; where 
 their food supply is most abundant; whether their most important 
 food resources are at all times sufficiently accessible to them, and 
 under sufficiently favorable conditions; what their food species feed 
 upon in turn; and so on down through the series of forms de¬ 
 pendent one upon another until we reach the primary sources of their 
 food, and the conditions of its greatest abundance and availability. 
 Next we need to know, for each important fish, its spawning times 
 and places; where such places are to be found; whether the fry can 
 escape from them in clue season, and if not, why not, and what can 
 be done about it; whether such most desirable spawning grounds 
 are present in the necessary abundance and of convenient access, and 
 if not, what can be done about that. All this involves, as it seems 
 to me, a systematic survey and description, from the fisheries stand¬ 
 point, of the whole congeries of waters—main river, tributary streams, 
 and connected lakes—so made as to lead to a clear discrimination 
 of their individual features as homes for fishes or places of oc¬ 
 casional resort, and leading also to a classification of them in definite 
 groups and kinds, each kind containing similar waters with simi¬ 
 lar surroundings. As soon, however, as we attempt to analyze, in 
 this sense, the environment and the needs of the more important 
 fishes, we find the essential elements of their welfare so interwoven, 
 in one direction or another, with those of virtually all the other or¬ 
 ganisms in their neighborhood, and determined at so many points 
 and in so many ways by the whole local system of things—biolog¬ 
 ical, chemical, and physical, aquatic and terrestrial, climatic and sea¬ 
 sonal—that there is evidently no fit way to our end except by a 
 general survey and analysis of that system as a whole. 
 
 My proposed program of investigation begins, consequently, with 
 a general natural history survey of the river and its tributary waters, 
 —with fishes, of course, in the lead, where they belong- biologically 
 as well as economically, since in them all the life of the waters cul¬ 
 minates and centers. A great river system however, is a large and 
 complicated unit to handle as one, and the Illinois with its two 
 hundred and seventy miles of length and its basin of twenty-nine 
 thousand square miles, proved to be too large a subject for us to 
 study with equal attention to all its parts. Such a river system may, 
 however, be readily analyzed into an assemblage of situations, each 
 situation perhaps many times repeated in different parts 01 the area. 
 
11 
 
 and a study of the river as a whole may be best organized and pur¬ 
 sued at first as a study of these typical situations out of which the 
 whole system is compounded. A large and varied group of such 
 characteristic features, all readily accessible from a single center, 
 was found at Havana, in the middle section of the Illinois basin, 
 and in that section, consequently, much the greater part of our work 
 on the river has hitherto been done. There we have gained, in the 
 course of years, a fairly exhaustive knowledge of the fishes of all 
 descriptions to be found in those waters, together with an approxi¬ 
 mate knowledge of the relative abundance of each in average years; 
 a knowledge of the preferred haunts and usual range of the various 
 species of fish, and some acquaintance with their annual migration 
 movements; a mass of data concerning their associations one with 
 another in the same situation and at the same time, and the compe¬ 
 titions for food and other necessaries which these associations ex¬ 
 press ; a fair acquaintance with both the average and the excep¬ 
 tional food of many of the species, including most of the really im¬ 
 portant kinds; a considerable body of information concerning their 
 breeding habits and their spawning times and places; an accurate 
 knowledge of both the composition and the quantity of the plankton 
 of our streams and lakes, obtained by several years of systematic 
 collection, measurement, and enumeration; a fairly full acquaintance 
 with the other animals and plants of the area—those which inhabit 
 the margin, live on the bottom, or lie buried in the mud; and a con¬ 
 siderable quantity of very interesting and really important material il¬ 
 lustrating the effect on the whole system of life of the Illinois river 
 produced by the opening of the Chicago drainage canal in 1900. We 
 have also majde many studies of the waters themselves in respect to 
 their physical and chemical characteristics and peculiarities under vary¬ 
 ing conditions and at various seasons, and have begun similar studies 
 of the mud and other materials of the bottoms of lakes and streams. 
 
 In this general field we now need merely to finish our studies 
 along special lines, and to extend somewhat the geographical range 
 of our detailed survey. We shall then be both ready and free to 
 take up special problems of immediate economic interest. Indeed, 
 much has already been done by us on such practical problems, as may 
 be seen from a few illustrations. 
 
 We learned a good many years ago—and this fact was first es¬ 
 tablished in Illinois—that virtually all our young fishes, whatever 
 their adult habits may be, live at first on the same kind of food. All 
 which hatch in like situations and at approximately the same time, 
 consequently, compete with each other when they first begin to feed. 
 
12 
 
 We have also learned that this first food—the minute plant and ani¬ 
 mal life of the water, called its plankton—is produced almost wholly 
 in the backwaters. Although flowing streams often carry an enor¬ 
 mous quantity of it, this mainly perishes presently in our great silt¬ 
 laden rivers. When, as in very low water in midsummer, the con¬ 
 tributions from the backwaters are reduced to a minimum, or per¬ 
 haps wholly cut off, the plankton of the stream also falls off to 
 little or nothing. Left to itself, indeed, even so slow a river as the 
 Illinois would virtually empty itself of plankton in a little while. 
 The fish-producing capacity of the stream is thus proportionate, other 
 things being equal, to the extent and fertility of the backwaters ac¬ 
 cessible from it, and contributing to it at the hatching time of 
 fishes. The plankton content of a stream at that time is, in fact, 
 an excellent index to the productive capacity of the waters as a 
 whole. 
 
 These facts have some interesting consequences, one of which 
 is that every useless fish is an injurious one, since it competes for 
 food, at least when young, with the useful kinds. By a useless 
 fish, however, I must be understood to mean one which is both val¬ 
 ueless to us and which does not contribute in any important way to 
 the maintenance of valuable kinds. 
 
 There is a notable harmony between the time of highest flood 
 in our great rivers, the spawning time of the bulk of our fishes, and 
 the climax period in the development of the plankton. All coming 
 together or following one another in quick succession, as they nor¬ 
 mally do, conditions are as favorable as possible for a large stock 
 of young fishes. The longer the period and the larger the scale 
 of the spring overflow, the better is the prospect for a heavy annual 
 contribution to the population of the stream. To this no doubt is 
 due the fact, clearly indicated by our recent river work, that the 
 plankton product of the Illinois system has been greatly increased 
 by the opening of the drainage canal from Lake Michigan and the 
 consequent raising of the average level of the river by about three 
 feet, this rise of river level of course resulting in a more wide-spread 
 and longer-continued overflow. 
 
 On the other hand, nothing can be more dangerous to the con¬ 
 tinued productiveness of these waters than a shutting of the river 
 into its main channel and the drainage of bottom-land lakes for agri¬ 
 cultural purposes. It is fortunate for our fisheries when one of these 
 lakes comes into the possession, or under the control, of a hunting 
 or fishing club, for this insures its maintenance. The time has come, 
 
13 
 
 in my judgment, when the state should consider seriously the policy 
 of preserving adequate breeding grounds and feeding grounds for 
 our river fishes, even if it has to acquire and maintain them, since 
 these waters are in imminent danger otherwise of being practically 
 depopulated. 
 
 It is another interesting conclusion from our recent work that 
 the enormous outpouring of Chicago sewage into the upper Illinois 
 improves rather than impairs its fitness for the maintenance 
 of fishes. The organic wastes thus emptied into the stream are laid 
 hold of by bacteria and Protozoa, and passed up by successive steps 
 to form the flesh and bones of fishes, and thus finally those of men. 
 The same may be said of the organic wastes of the towns along the 
 banks of the stream. 
 
 Still another conclusion of considerable practical interest may be 
 here mentioned, although it grew out of our aquatic work outside 
 the Illinois basin. One large section of the state of Illinois, com¬ 
 prising about a fifth of its area, is peculiar in the absence, or at 
 least in the unusual rarity there, of a considerable group of fishes 
 which are abundant elsewhere in the state and elsewhere in the sur¬ 
 rounding territory. Now this section, the conditions of which these 
 fishes evidently do not tolerate, is distinguished from the remainder 
 of the state by its geological history, and, as a consequence, by the 
 different character of its soil and of its streams. The soil is so 
 finely divided that its particles can not be wholly separated from the 
 water, even by repeated filtering with the finest filter papers, and 
 it thus remains persistently and perpetually turbid. The fishes which 
 seem to avoid this situation are, on the whole, those which we find 
 in other parts of the state to be relatively infrequent in very muddy 
 water. The inference is plain that it is the permanently muddy char¬ 
 acter of these southern Illinois streams, itself due to the geograph¬ 
 ical history of the district, which renders them unfit for these more 
 sensitive fishes. Any attempt, consequently, to increase the number 
 of such fishes there would be foredoomed to failure. Doubtless 
 there are many other instances of the same sort to be found in 
 other parts of the country, and it seems possible that various mys¬ 
 terious failures of attempts made to introduce new fishes are at¬ 
 tributable to some such cause, not taken into account because un¬ 
 known. 
 
 We have now a long- waiting list of special practical inquiries 
 which seem clamoring to be made. We need, for example, to ob¬ 
 serve most carefully the European carp, now undergoing enormous 
 multiplication in our interior waters; to learn the details and the 
 
14 
 
 variations of its food and its habits under different conditions; to 
 study the bearings and consequences of its spread and increase on the 
 welfare of our native fishes, and on the whole system of fresh-water 
 life; to watch for evidences of local over-population by it, to be sus¬ 
 pected when the carp or its competing species fall below the average 
 in size and plumpness, or when epidemic diseases appear among them; 
 to follow the course of events in its principal spawning grounds, 
 where our own observations show that tremendous losses, amounting 
 to a local extermination of the young, may occur under usual condi¬ 
 tions; and to determine, by the use of numbered tags, the range of 
 the wanderings of this and other fishes, and especially to learn how 
 far the various species usually go from the places where they were 
 hatched. We have a rare and remarkable opportunity in Illinois 
 to watch the progress of a biological revolution as important to the 
 life of our waters as was the Norman invasion to the life and his¬ 
 tory of England. Fortunately, we have for comparison with present 
 and future conditions, the materials and records of several years’ 
 systematic and connected work done on the Illinois river before 
 the opening of the drainage canal into Lake Michigan, and when the 
 carp was but just beginning to make its presence felt as a disturber 
 of the then existing order. 
 
 I can not, within the time limits of your program, go further with 
 the development of this subject, and I must content myself with 
 these sample fragments of its discussion. When the results of our 
 river work began to appear several years ago, a leading American 
 zoologist wrote me that the Illinois promised to become very soon 
 the best known—because the best studied— of any river in the world, 
 and we have been at work a good deal of the time since in an ef¬ 
 fort to increase still further our knowledge of that stream and the 
 public appreciation of its value. In the face of the gigantic inter¬ 
 ests—agricultural, industrial, commercial, and political—which are 
 now mustering along its course, with huge schemes in hand for 
 revolutionary operations upon its channel, its banks, and its back- 
 waters, we feel that we need all the backing and assistance we can 
 secure from those concerned in the preservation and development of 
 our native fisheries; and no agency, I am sure, is in a position to 
 give us more effective aid than this old and influential American 
 Fisheries Society. Especially we shall value your suggestions both 
 as to subjects deserving early investigation, and also as to practical 
 measures possible and desirable on the basis of such knowledge as 
 we now have or may presently acquire. 
 
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The valley of the Illinois from Starved Rock, near Ottawa, Ill. 
 
In Horse-shoe Canon, near Ottawa, 111 
 
 
1'he valley of Hie Illinois from Prospect Heights, above Peoria, 111. 
 
Characteristic views from the middle course of the Illinois River 
 

 Permanent overflow of Illinois River bottoms. In “cut road 
 leading into Thompson’s Lake. 
 
View of Flag' Lake, 1910. 
 
aboratorv-boat ami station launch. 
 
On the breeding- grounds, watching movements of fish, and searching for fish nests and fry. 
 
Mud-borer and equipment for collecting and assorting materials of bottom. 
 
Preserving - a plankton catch, in station launch. (Richardson, naturalist ; Allen, fisherman and engineer.) 
 
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UNIVERSfTY OF ILLINOIS-URBANA 
 
 3 0112 068175659