DISTRIBUTION AND FOOD OF THE FISHES OF GREEN 

 LAKE, WIS., IN SUMMER. 



By A. S. PEARSE, University of Wisconsin. 



CONTENTS. 



Page- 

 Introduction 255 



Distribution of the fishes 256 



Food of the fishes .' 262 



General remarks on foods 266 



Discussion and conclusions 270 



Bibliography 272 



INTRODUCTION. 



Green Lake is of particular interest on account of its depth (237 feet). It measures 

 1 1.9 km. in length, 3.22 km. in width, has a maximum depth of 72.2 m., and a mean 

 depth of 33.1 m. Its area at a depth of 70 m. is 2.1 km.^ The water is very clear and 

 the plankton content rather poor. The shores are for the most part sandy or stony, 

 and the slope of the beaches is usually deep. 



During the summer of 19 19 the writer camped at the western end of the lake from 

 August II to September 5. In front of the camp was a considerable stretch of sandy 

 beach (frontispiece) ; the deepest parts of the lake and Spring Lake Creek (at the south- 

 west comer of the lake) were readily accessible by rowboat. Temperatures were 

 taken once each week and are recorded in Table i. 



Table i. — Temperatures of Green Lake in Degrees Centigrade, 1919.' 



Depth, in meters. 



Aug. 14 . 

 Aug. 20.. 

 Aug. 38. . 

 Sept. 4. . 



31. 7 



30. 7 

 19.7 



16.4 

 15.8 

 20. 6 

 19- S 



9-5 

 13-2 

 12.6 

 16.6 



8.1 

 9-5 

 9.1 

 9.9 



6.4 

 6.6 

 6.0 

 7-1 



S-7 

 S-8 

 6.0 

 6.15 



5-2 

 5-5 

 5-8 

 S-I 



S-o 

 S-o 

 S-o 



4.9 

 4.9 

 4.9 

 4.8 



' The deep-sea thermometer used in taking the temperatures was loaned by C. Juday, of the Wisconsin Geological and 

 Natural History Survey. 



