262 BULLETIN OF THE BUREAU OF FISHERIES. 



hundreds of hauls) there is no doubt that the opposite is true in Lake Mendota. The 

 Johnny darters are characteristic shallow-water fishes on sandy shores everywhere in 

 Wisconsin. Some lakes, however, have other species of darters more abundant along- 

 shore. For example, the Iowa darter {Etheostoma ioivcE, Jordan and Meek) is the abun- 

 dant one in Oconomowoc Lake. The minnows are characteristic more or less of all 

 shallow-water habitats. The perch ranges through all bottom habitats and is probably 

 the most versatile of our lake fishes. The pickerel, bass, and bluegill belong with the 

 shore vegetation, and, as vegetation is not very plentiful in Green Lake, these fishes are 

 not numerous. 



On the evening (6.30 p. m.) of September 2, a trot-line 20 feet in length, bearing 

 49 No. I Limerick hooks baited mth earthworms, was set outside a rush-grown bar 

 extending from the bay behind Blackbird Point (front.) westward; depth, 1.2 to 2 m. 

 Next morning (6.30 a. m.) the catch was i bluegill, 5 perch, i dogfish. At 6.50 p. m. 

 on September 3, 50 hooks were set inside the same bar (i to 1.5 m.) on 200 feet of line. 

 The catch at 6.50 a. m. on September 4 was 7 bluegills, 4 perch, i rock bass, i mussel, 

 Lampsilis lulcola (Lamarck). 



If these trot-line catches mean anything, they indicate that there are more blue- 

 gills inside the bar and that perch occur in equal numbers on either side. Perch, as 

 has been suggested heretofore, are versatile fishes which invade practically all available 

 habitats. Bluegills, though fitted to live among aquatic vegetation, are remarkably 

 quick to take advantage of any new sources of abundant food. An instance of this 

 was observed in Green Lake on the evening of August 22. The lake was very calm 

 and on its surface were numerous ants, of some species that had been making its nuptial 

 flight during that day. The whole surface of the west end of the lake was at intervals 

 marked by litde ripples caused by fishes feeding on the ants. All fishes observed from 

 a rowboat before darkness fell were bluegills, though other species were doubtless 

 taking advantage of this unusual supply of food. 



FOOD OF THE FISHES. 



The foods eaten by the fishes of Green Lake in 19 19 are given in the following lists. 

 The figures used in connection with foods all mean per cent by volume as estimated by 

 the writer at the time of examination; + indicates an amount less than o. i per cent. 

 Lengths of fishes are given in millimeters and do not include the caudal fin. Fishes are 

 arranged in alphabetical order according to scientific names. Summaries for all species 

 are given in Table 8. Unless otherwise mentioned all catches are off the sandy shore 

 at the east end of the lake (frontispiece) . 



Ambloplites rupestris (Raftnesque). Rock bass. 



August 16. — Depth, 8 m.; number examined, i; length, loS. Food: Chironomid pupa;, 2; cray- 

 fish, 98. 



August 22. — Number examined, i; length, 30. Food: Chironomus larva;, 25; mayfly larvs, 50; 

 Hyalella, 20; Eurycercus, 5. 



August 23. — Number examined, i; length, 47. Food: Chironomus larvae, 5; large blue water 

 mite, 30; ostracods, 2; cyclops, 12; Eurycercus, 3; Ceriodaphnia, 18; sand, 30. 



August 26.— 'HumhtT examined, 2; lengths, 192, 57. Food: Chironomus larvae, 2.5; C. pups, 

 2.5; crayfish, 50; Ceriodaphnia, 45.5. 



August 2y, 28. — Number examined, 2; lengths, 190, 208. Food: Crayfish, 100. 



