Carrying Capacity and Sfandiiig Crop 67 



October in 1955. With the exception of about 700 sniallmoutli bass that 

 were stored in the pond from October, 1952, to Marcli, 1953, tlie fish 

 population has consisted of the four species hsted above. In the 1950 

 census (Table 4.1), the bluegills and the bullheads dominated die popula- 

 tion; and when fish were restocked following die first census, only 1093 

 bluegills and 1069 bullheads were returned. In die 1950-1952 period, the 

 bass made the greatest gains (80 fish expanded to 1057), die bluegills 

 increased about 2.5 times, and the bullheads dropped from 1069 to 63 

 individuals. This reduction in bullheads reflected poor reproductive suc- 

 cess and a heavy hook-and-line yield. Following the March, 1952 census, 

 fish replaced in the pond were 541 bass weighing 72.1 pounds, 569 blue- 

 gills weighing 140.6 pounds, 16 warmouth weighing 4.2 pounds, and 

 36 black bullheads weighing 25.6 pounds. The fishing in Arrowhead Pond 

 in 1953 was rather light until October when fishermen discovered that 

 smallmouth bass taken in draining another lake were being stored in 

 Arrowhead. Then, it appeared that considerable poaching occurred. 



Following the 1953 census, 104 largemouth bass weighing 56.1 pounds, 

 834 bluegills weighing 91.6 pounds, 427 warmouth weighing 41.3 pounds, 

 and 30 bullheads weighing 14.8 pounds were returned to the pond. 



During die process of draining the pond in March of 1955, the outlet 

 valve was opened wide at night by someone unknown. The next morning, 

 the fish were scattered along the outlet channel for several hundred 

 yards, and footprints indicated that some pre-dawn collection of fish may 

 have taken place. Thus, the 1955 census may be short some large bass and 

 large bluegills. 



The four censuses of Arrowhead Pond showed a range of standing 

 crops from 164.3 to 254.5 pounds per acre. The total poundage was lowest 

 when the bass were the most numerous and highest when bluegills and 

 bullheads were abundant. All of these fish except the warmouths appeared 

 to be in competition, each species ready to "take over" the pond if an 

 opportunity should arise. 



The fish population of Ridge Lake ( central Illinois ) has been censused 

 by draining 8 times in the past 20 years ( Bennett ^^ and unpublished 

 data). Numbers and weights of fish per acre taken in these censuses are 

 listed in Table 4.2. The time interval between each of the first 5 censuses 

 was two vears; between the fifth and sixth and the sixth and seventh 

 censuses, three years, and between the seventh and eighth censuses, three 

 and one-half years. Each September, 1951 through 1955 inclusive, the 

 water level of Ridge Lake was lowered to reduce the surface area during 

 the fall months so that the fish populations exposed in the 1953 and 1956 

 censuses were hardly comparable to the others. Table 4.2 shows that 

 after 1945 the population was composed largely of bass and bluegills. 

 No bluegills were stocked until 1944, a year after the 1943 census. War- 



