In addition I found an article that provides that BG , as common sense would tell you , eat a bunch of tilapia yoy/fry. So the tilapia will take pressure off the BG because they are an alternate source of food for LMB and they provide food for a lot of BG. Better fed BG are in better condition and produce more BG egg/fry. Further since 3-4in BG are the biggest predator in #s on small BG (yoy/fry) and they are eating yoy tilapia you may get higher survival rates for BG yoy. Thoughts or comments ?

Vulnerability of Redbelly Tilapia Fry to Bluegill

Predation with Changes in Cover Availability


WESLEY B. BICKERSTAFF � AND CHARLES D. ZIEBELL

Arizona Cooperative Fishery Research Unit 2

WILLIAM J. MATTER

The University of Arizona


ABSTRACT

The successful use of redbelly tilapia (Tilapia zilh') to control aquatic plants in ponds with game

fish depends on high survival of tilapia young. We tested the vulnerability of redbelly tilapia fry

under parental care to predation by bluegill. Experiments were conducted for a 3-day period in

5.5-m diameter pools at three levels of artificial plant cover (25, 50, and 75%) and at two densities

of predators (15 and 20 per pool). Predation rates on 14-day-old, unprotected fry also were deter-

mined. Fry survival was lowest with 25% cover (mean 40%) and highest with 75% cover (mean

72.5%). The survival of fry at 50% cover (mean 68.2%) was significantly higher than survival at

25% cover, bnt there was no significant difference in fry survival between 50 and 75% cover. Fry

survival was poor without parental care, ranging from 6 to 34%. Extrapolation of the survival data

indicated that too few Tilapia zilli, when stocked with predatory game fish, would survive to the

size where they could adequately control aquatic plants.