ECOLOGICAL NOTES ON THE FISHES OF 

 WALNUT LAKE, MICHIGAN 



By T. L. Hankinson 



It is well known to ichthyologists that different species 

 of fishes live under different conditions in our bodies of 

 water ; some prefer shoals, others deep water ; some spend 

 much time near the surface; and every kind has a habitat 

 which it prefers and in which it best thrives. Investigations 

 to find out these habitats and the relations of the fishes to 

 them promise interesting and important results, especially 

 to fish culturists. Such was the chief purpose of the work 

 on fishes of Walnut Lake in Oakland County, Mich., done 

 by the writer for the Michigan Biological Survey in the 

 spring and summer of 1906. With the assistance of Mr. 

 Elmer McDonald and Mr. Ellis Michael in the field and by 

 means of valuable suggestions from Prof. J. E. Reig- 

 hard and Mr. Charles C. x\dams and from a number of 

 other scientists acquainted with methods of studying aquatic 

 life, some results in the way of data and generalizations of 

 ecological importance were obtained, which will be con- 

 sidered in this paper.* 



Walnut Lake is one of the many small lakes of the more 

 recently glaciated part of the country, which includes 

 Michigan. It is about a mile in length and some less in 

 width, being roughly oval with a very irregular shore-line. 

 Its surface area was about 230 acres. The maximum depth 

 found by the surveyors was slightly over a hundred feet. 

 Its bottom, in the shallower water, was for the most part 

 of a very pure marl. The drainage of the lake is poor, 

 there being no natural outlet, but an artificial one connects 

 its waters indirectly with those of the Rouge River. The 



*For details concerning the work at Walnut Lake see T. L. Hankin- 

 son, Report of the Michigan State Board of Geological Survey for 1907. 



