If the loss of fishes were complete, the body of water could be restocked with desirable 

 species during the following spring In order to produce good fishing by the second summer. In the 

 case of a partial kill, the relative abundance of the Individual species making up a population is 

 often radically changed; some species may be entirely eliminated and those that survive may be the 

 kinds of fishes least desirable for angling. Once these undesirable fishes spawn, and the young re- 

 place the lost population, the body of water may require draining and restocking If It Is to produce 

 a crop of hook-and-llne fishes. Even In lakes that contain only game and pan fishes, as for example 

 largeroouth bass, crapples, bluegllls, and bullheads, the elimination of the predatory bass by winter- 

 kill will allow the others to overpopulate the lake rapidly, with the result that stunting will 

 eventually ruin fishing. 



Early In the summer of 1941, I visited a water-filled gravel pit of about 50 acres, located 

 In Kane County, Illinois, where winterkill of fishes during the winter of 1940-41 was said to have 

 been conplete. Hundreds of pounds of largemouth bass, white crapples, bluegllls, and bullheads were 

 reported to have been piled along the shores following the melting of the Ice. However, at the time 

 of my visit, s^lne hauls In shallow water took thousands of small bluegllls and golden shiners. No 

 adults of these species were taken and probably only a few survived. The fish population then present 

 could not produce good fishing because of the elimination of the largemouth bass. Without bass to 

 hold the bluegllls in check, overpopulation and stunting naturally followed. The introduction of 

 several thousand bass flngerllngs during the summer of 1941 might have resulted In good fishing In 

 1942 for both bass and bluegllls. 



Following the winter of 1944-45, a severe winterkill of fishes was apparent In Gale Lake, 

 near Galesburg, Illinois. About 4, 000 pounds of fish carcasses were collected after the Ice went out 

 In March. Local observers reported that the fishes consisted of largemouth bass, white crapples, 

 bluegllls, green sunflsh, black bullheads, carp, buffaloes, and golden shiners. On the basis of the 

 carrying capacity of the lake. It Is estimated that about 80 per cent of the population (by weight) 

 had been killed. 



In September, 1946, the lake level was lowered and the fish population was censused. This 

 census showed clearly the composition of the population that survived the winter of 1944-45, and the 

 ability of this reduced population to replenish the lake. The species composition of the new popu- 

 lation was highly undesirable from the standpoint of angling. 



DESCRIPTION OF GALE LAKE 



Gale Lake was built by the Chicago, Burlington, and Qulncy Railroad Company In 1870-71 to 

 furnish a water supply. This 10-acre lake (map, frontispiece) originally had a maximum depth of about 

 20 feet, which by 1944 had been reduced to 10 feet by the deposition of silt In a period of over 70 

 years. As the valley floor Is relatively flat, the average depth In the main body of the lake Is ap- 

 proximately 9 feet. Runoff water from the land south of the lake enters the lake proper through a 

 south bay a few hundred yards In length. Deposition of silt has made this bay much shallower than thej 



rest of the lake. 



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