Biological Survey — Erie-Niagara Watershed 15 



tions and contribute a requisite type of data to a proper under- 

 •standing' of conditions. 



The full report of the biologist includes a description of the 

 bottom conditions prevailing along the shore, in the harbors and 

 in the Niagara river. A tabulation of pollution conditions in the 

 streams of the watershed provides data of importance to each 

 community in which studies have been made. The types of pol- 

 luting substances which enter the river system are discussed in 

 their relation to fish life and to the organisms associated with 

 them in the capacity of food of fish either directly or remotely. 

 The mileage of streams noticeably affected by the polluting wastes 

 is estimated at about 54 miles, 49 of which would be suitable for 

 fishing streams. 



One of the foremost difficulties confronting one in the investi- 

 gation of polluting conditions is to establish proof of the effects of 

 pollution on the fish themselves. These difficulties require methods 

 which can be translated into means for detecting these effects. The 

 physiologist in his investigations during the survey has given 

 emphasis to new considerations in the study of pollution by using 

 the blood of fish as a test of the effects of pollution. These studies 

 of the blood furnish new clues of such injury. The studies this 

 season have made important contributions to our knowledge of 

 normal blood values in fish and the effects of weak acid solution. 



Pollution damage to either young or adult fish cannot be always 

 estimated adequately by the usual means of a minnow test. The 

 emphasis, therefore, on the blood test enables us to change our 

 strategy by placing more reliance on methods showing why the 

 fish die rather than on how long it takes them to die. 



Stocking Lists and Maps. — A key map of the watershed affords 

 a convenient guide in locating the particular quadrangle, county 

 or township in which the reader is interested. It also serves to 

 orient in the watershed the quadrangle maps* (U. S. G. S. topo- 

 graphic maps) adapted for purposes of record in the survey. On 

 these maps all streams are shown with suitable indications of 

 dry and permanent streams, the ])resence of springs, pollution 

 outfalls, favorable places for fish planting and the appropriate 

 species. Accompanying the maps are the stocking lists which set 

 forth in tabular form the name of the streams (if not named then 

 numbered), the mileage available for stocking and the stocking 

 ])olicy per mile. By reference to these tables and maps the loca- 

 tion of the best places to plant fish and the calculation of the 

 number per mile may be determined readily. 



Certain species, such as, bluegill sunfish and crappie, which 

 have not hitherto been planted in the watershed are recommended 

 for suitable waters. These additions should improve basically the 

 fishing for ''pan fish," giving greater diversity to this activity. 



The Colored Plates. — The reproductions in color (Plates Nos. 

 1-8) command attention in one or more directions according as they 



See maps following App. III. 



