May, 1945 



Bennett: Overfishing, Onized Lake 



405 



few managed to escape for two more sum- bers of fish per acre ranged from 10,119, 



mers. None had completed the sixth year where a large number of minnows were 



of life. present, to 1,124; the average number per 



The hook-and-line yield of 349.95 acre was 3,434. The fact that Onized 



pounds per acre in 1939, table 4, is judged Lake contained more than the average 



Much of the angling at Onized Lake is done by families or other small groups that use the 

 club grounds for picnics. Because fishing is incidental to other uses, the angling pressure on this 

 body of water is less closely related to the catch of fish than on most other lakes. 



to be about three-fourths of the carrying 

 capacity of Onized Lake for the species of 

 fish then in the lake. The carrying capac- 

 ity, on the basis of that found in other 

 similar ponds, is believed to lie between 

 450 and 500 pounds of fish per acre, as the 

 average for Onized Lake and 21 other 

 small Illinois lakes censused was 446.5 

 pounds per acre (Bennett 1943). In the 

 final census of 1941, the total weight of 

 fish in Onized Lake was only 221.09 

 pounds per acre, table 7, plus a few pounds 

 for the numerically abundant 1941 brood 

 that was not recovered. The number of 

 fish collected per acre was 4,586. In the 

 21 other small lakes mentioned above, 

 which were censused in a manner similar 

 to the census of Onized Lake, the num- 



number of fish per acre, although over- 

 fished, indicates that numerically the pop- 

 ulation was maintaining itself (in spite of 

 no additional stocking), and that, with 

 reduced fishing pressure, the population 

 would have increased rapidly in total 

 weight, until it approached the carrying 

 capacity of the lake. 



Summary 



1. Onized Lake, a small pond of 2 

 acres, offered an excellent opportunity to 

 study overfishing because it was fished in- 

 tensively and a creel census was made of 

 the catch. 



2. The creel census covered September 

 and October of 1938, the fishing seasons 



