American Fisheries Society 183 



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 due 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 fish- 

 eries standpoint, 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 occasional resort, and lead- 

 ing also to a classification of them in definite groups and 

 kinds, each kind containing similar waters with similar 

 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 organisms in their neighbor- 

 hood, and determined at so many points and in so many 

 ways by the whole local system of things — biological, 

 chemical, and physical, aquatic and terrestrial, climatic and 

 seasonal — 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, conse- 

 quently, 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 culminates 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 thou- 

 sand 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 as- 

 semblage of situations, each situation perhaps many times 



