. Bulletin. Natural history; Natural history. Illinois Natural History Survey Bulletin Vol. 29, Art. 1 15 and Fig. 34). The 2-year-old white crappies of 1950-1952 had smaller av- erage lengths than the 2-year-olds of any other year of our study. The 2-year- old fish of 1953 showed a drastic in- crease in growth rate (as measured by WHITE CRAPPIE. 2 l&O-, eo- 1950 1952 1954 1956 1958 BLACK CRAPPIE ^ yeors ^ °1'^ 1954 1956 1958 We did not find that any correlation (;'^—) existed between the growth indices of 3- and 4-year-old white crap- pies and the Lake Chautau
. Bulletin. Natural history; Natural history. Illinois Natural History Survey Bulletin Vol. 29, Art. 1 15 and Fig. 34). The 2-year-old white crappies of 1950-1952 had smaller av- erage lengths than the 2-year-olds of any other year of our study. The 2-year- old fish of 1953 showed a drastic in- crease in growth rate (as measured by WHITE CRAPPIE. 2 l&O-, eo- 1950 1952 1954 1956 1958 BLACK CRAPPIE ^ yeors ^ °1'^ 1954 1956 1958 We did not find that any correlation (;'^—) existed between the growth indices of 3- and 4-year-old white crap- pies and the Lake Chautauqua water levels (Fig. 35). The calculated corre- lation coefficient may be misleading, since more than one age-group was in- volved in the computation. In 1953, a year of low water levels, the 2-, 3-, and 4-year-old fish showed increases in av- erage lengths (Fig. 34). In 1956, a year of low water levels, the 2- and 4-year- old fish showed increases in average Fig. 34.—Year-to-year variations in growth rates (as indicated by length I of 2-, 3-, and 4-year-old white crappies and black crappies at Lake Chautauqua, 1950-1959 (data from Table 15 and Table 18). average length in the fall), and 2-year- old fish continued to show good growth rates each year through 1959. The im- proved growth rates probably were re- lated to the comparatively small popu- lations of crappies present in the lake after 1952. The average lengths of the 3- and 4- year-old white crappies varied less from year to year than the average lengths of the 2-year-olds. After 1956, the average lengths of the 3- and 4-year-old fish de- clined slightly. By 1958 and 1959, the average lengths of fish of these ages had dropped to about where they had been in 1950 and 1951. The length data given here on the 3- and 4-year-old white crappies indicate that the increased re- moval of commercial fishes had no ap- parent beneficial effect on growth of these Please note that these images are extracted from scann
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