The conditions which make Western Lake Erie especially subject to 

 pollution are: (1) the presence of large industrial communities on the 

 shores of Maumee, Raisin, and Detroit Rivers, which empty into this part 

 of the lake; (2) the extreme shallowness and consequent small volume of 

 waterj(3) the presence of two peninsulas and numerous islands which par- 

 tially separate this area from the rest of the lake and v±iich tend to 

 prevent free outflow of the vfater. The importance of V.'estern Lake Erie 

 in the fishery arises from the facts that (1) lart^e numbers of fish are 

 caught there, (2) the area is used as a spawning groiind by all of the com- 

 mercial species except, possibly, the blue pike-perch. Because of the 

 supposed intensity of pollution here and the unusual opportunity for it to 

 be harmful to fishes, particularly during their early s tages of development, 

 it was generally believed that investigation should center in the western 

 part of the lake. It was believed, too, that, if it could be shown that 

 pollution was not the controlling factor in the depletion of the fishery 

 here, pollution could be ruled out as a controlling factor elsewhere in the 

 Great Lakes. 



The present report includes the results of a series of limnological 

 investigations begun by the Conservation Division of the State of Ohio in 

 1926, and continued in parts of the years 1927, 1928, 1929, and 1930. A 

 history of these investigations will be presented in later pages. 



Previous Investigations in Lake Erie 



Prior to 19-6 no comprehensive survey of the physical, chemical, and 

 biological conditions in Lake Erie had been made. This should not be taken 

 to mean that nothing was knovm of such conditions. On the contrary there 

 had been accumulated, over a period of years, much information concerning 

 morphometry, temperatures, currents, chemical :;nnstituents of the water, 

 the kinds and general abundance of the plants and animals, and many related 

 subjects. The literature covering the flora and fauna of the lake was par- 

 ticularly extensive as a result of the activities of investigator 3 at the 

 Lake Laboratorj' (later the Franz Theodore Stone Laboratory) of Ohio State 

 University (see bibliographies compiled by Miller (1933) and Osbom (193^)). 

 In addition there had been some studies of the abundance of plankton, and 

 numerous sanitary surveys to determine the suitability of the water for domes- 

 tic consumption. 



The nearest approach to a limnological survey such as the one reported 

 here, was the investigation begun in 1898 under the auspices of the United 

 States CommiFsion of Fish and Fisheries. In that year Professor Jacob E. 

 Reighard was placed in charge of a staff of workers and a laboratory at 

 Put-in-3ay. During the four years that the laboratory was maintained, 

 much v;as learned of the organisms of the lake, but the original plans for a 

 unified program of research were not realized. Following the abandonment 

 of the laboratory in 1902, limnological investigations of the survey type 

 were not taken up again until I926. 



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