May 13-16, 1958, 327 hybrids, which averaged 6.8 inches 
and ranged in length from 5.2 to 8.1 inches, were trap- 
ped and removed from the pond. 
BG Fy Hybrids. — Sixty-one (200 per surface acre) 
hybrid fry were placed in a 0.3-acre pond on July 3, 
1956. Less than 3 years later, on May 8, 1959, this 
pond was treated with rotenone, and 10 Fy hybrids 
were collected, fig. 5; they averaged 8.6 inches and 
the hybrids were recaptured. After 2 growing seasons, 
these 44 hybrids averaged 6.9 inches and ranged in 
length from 5.2 to 7.5 inches. 
GROWTH OF PARENT SPECIES AND F, HYBRIDS 
Two experiments were conducted to directly compare 
growth rates of hybrids with those of their parent spe- 
Fig. 5. — Seven of 10 BG Fy hybrids collected from a 0.3-acre pond after approximately 3 years of growth. These hybrids 
averaged 8.6 inches in total length and 0.74 pound in body weight. 
ranged in length from 7.2 to 9.2 inches. In weight the 
fish averaged 0.74 pound and ranged from 0.50 to 0.86 
pound. 
GB Fy Hybrids. —- On August 26, 1957, 322 (800 
per surface acre) hybrids, which averaged 1.5 inches 
total length, were placed in a 0.4-acre pond. Wire traps 
were set in this pond on October 18, 1959, and 44 of 
10 
cies. In the first experiment, a pond which contained 
no other fish was stocked with equal numbers of BG Fy 
hybrids and green sunfish of approximately similar 
ages and sizes. In the second experiment, another pond 
was stocked in a similar manner with GR Fj hybrids, 
green sunfish, and red-ear sunfish. In both of these 
experiments the population densities of fish were con- 
