Table 5.— The numbers of green sunfish and BG Fy hybrid sunfish placed in an 0.8-acre pond and the numbers and the 
percentages of the original stock recovered 10 months later. 
Category 
Fish used in stocking (July 10, 1958) 
Fish trapped and removed (April 29-May 8, 1959) 
Fish recovered during rotenone census (May 8-11, 1959) 
Total fish recovered (trapping and rotenone census) 
Fish unaccounted for 
Green Sunfish BG F, Hybrids 
171 100 100 
123 72 68 
4 v2 15 
17-7 74 83 
26 
Table 6.— Number and weights of green sunfish and BG Fy hybrids of various length classes recovered 10 months after 
release in an 0.8-acre pond. 
Green Sunfish 
BG F, Hybrids 
Total 
Length, [| womnes om Weighs 
Inches of Fish Range, Average of Fish Average 
Grams Grams | Pounds 7 Pounds 
*The average total length of green sunfish males was 4.9 inches, females 4,4 inches; BG Fy hybrid males 5,3 inches, females 5.0 inches. 
GR F] Hybrids vs. Green Sunfish and Red-Ear Sun- 
fish. —During the period August 1-15, 1958, 200 GR Fy 
hybrids averaging 4.6 inches total length, 200 green 
sunfish averaging 4.2 inches, and 200 red-ear sunfish 
averaging 3.5 inches were placed in a 1.l-acre pond 
that contained no other fish. During the spring of 1959 
(April and May) some of these fish were taken by hook 
and line, some were trapped, and the rest removed by 
rotenone treatment of the pond. One hundred forty-nine 
GR F] hybrids, 136 green sunfish, and 127 red-ear sun- 
fish were recovered. The numbers of fish recovered by 
each of the three methods of collection, the length- 
frequency distributions, and the range of weights are 
shown in tables 7, 8, and 9. 
12 
The population densities in this pond were low. 
When the experiment was terminated, there were 26, 
21, and 14 pounds per acre of GR Fy hybrids, green 
sunfish, and red-ear sunfish, respectively, in the pond; 
the fish ranged in length between 4.5 and 7.0 inches. 
This pond had in the past supported more than 150 
pounds of sunfish per surface acre. Fish in this ex- 
periment grew at an exceedingly rapid rate; they in- 
creased in length about 2 inches (average) and nearly 
doubled their weight between August of 1958 and late 
May of 1959. The results of this experiment give addi- 
tional support to the concept that in uncrowded ponds 
there is little difference in the growth rates of hybrid 
sunfish and their parent species. 
