TABLE 17.— HOOK-AND-LINE CATCH FROM FORK LAKE, 1939. 



Date 



Bait Used 



Nmnber 



of 

 Persons 



Hours 

 Fished 



Number 



of 



Fish 



Fish Per 

 Man-Hour 



Pflueger pippin 



Womis and spinner 



Spinner fly 



Spinner fly 



Trout flies 



Worms and Pflueger pippin. . . . 

 Trout flies and Pflueger pippin. 



Trout flies 



Trout flies 



Suet and grasshoppers 



Flies and small hair crayfish. . 



Iferch 34. 



April 11. 

 April 13. 

 May 28. . 

 May 30. . 

 June 22 . 

 June 28 . 

 July 25 . 

 Sept. 8 . 

 Sept. 18. 



TOTAL MAN-HOURS 55.2 



TOTAL FISH CAUGHT 241 



AVERAGE CATCH PER MAN-HOUR . . . 4.37 



1 

 2 

 1 

 1 

 2 

 8 

 2 

 3 

 1 

 2 

 1 



2.00 

 2.00 

 0.33 

 0.33 

 4.50 

 2.13 

 2.00 

 2.66 

 2.00 

 3.00 

 2.50 



4 

 2 

 

 



39 

 131 



11 



25 

 4 

 5 



20 



2.00 

 0.50 

 0.00 

 0.00 

 4.33 

 7.69 

 2.75 

 3.13 

 2.00 

 0,83 

 8.00 



Success of fishing seemed to depend upon the transparency of the water; as the water 

 became clearer, the catch of fish increased. Table 18 shows this relationship. 



TABLE 18.-- -CORRELATION BETWEEN TRANSPARENCY AND FISHING. 



Transparency, Feet 



Number of Fish 

 Per Man-Hour 



0.5 to 2.0 

 2.0 to 2.5 

 3.5 to 4.5 



2.04 

 2.86 

 6.53 



Bass and bluegills feed by sight, and as the water clears the field of vision in- 

 creases, allowing the fish to see both food and baits at greater distances, 



EROSION CONTROL 



In view of the apparent effect of transparency on fishing, erosion control becomes an 

 important item in management practices for artificial lakes. In 1938, Dr. Lee E. Yeager, 

 Forester of the Natural History Survey, suggested a plan of erosion control for Fork Lake, 

 This plan has been partly carried out and is being continued in 1940, A small area of raw 

 subsoil along the shore north of the dam needs to be revegetated. Here lespedeza is re- 

 commended for planting after a layer of dark loam has been worked over the clay surface. 

 Several small gullies on the slopes above the lake need to be controlled by check dams of 

 heavy sod. These dams should be about 15 feet apart. The silt which collects between 

 them should be planted to lespedeza. Soil-binding shrubs should be planted on the lower 

 face of the dam and the steep slopes around the lake. 



DISCUSSION 



More than a half century of fisheries Investigation carried on by the Illinois Natura! 

 History Survey and Its predecessors, the State Laboratory of Natural History and the State 

 Musevim of Natural History, have forced us to the conclusion that rather complete informa- 

 tion on a few individual bodies of water over a long period of time can give more valuable 

 information than a much larger volume of data taken at various seasons from hundreds of 

 different localities. Fork Lake is being i;ised intensively as an experimental lake until 

 the time when the experimental lakes at Fox Ridge State Park, near Clmrleston, and Dixon 

 Springs Lake, in extreme southern Illinois, are completed and put into operation, ^ 



Although Fork Lake has an area of only 1.38 acres, our fisheries Investigations there 

 have given us much valuable experience in planning the investigational program to be 

 carried out in these larger lakes (23 and 82 acres, respectively), 



A deliberate attempt has been made to simplify the investigations at Fork Lake by 

 limiting the fish population to largemouth bass and bluegills. The yield during 1939 was 

 162 pounds per acre and we propose to attempt to double it during 1940, The carrying 

 capacity of this lake for carnivorous fish, as estimated from the 1938 census, is about 

 300 pounds per acre. Since the fish population now consists mostly of yearling bass and 

 yearling bluegills, it does not seem likely that the food resources of the lake are being 



22 



