Before i say anything , this is going to be long but im trying to get help with stocking rates on something very few people have done before, I assume. I'm hoping that experts can analyze this data and maybe we can come to some kind of concensus. Greg, Have you tried pasting that link? it works when i click on it. Wish i could tell you how but I'm no computer wiz. I'll give you the meat. But understand that I live in Brownsville, TX (born in Ga though)and the tilapia in my area live year round. avg winter temps are about 65 degrees. So to answer your ?about the BG. How long does it take for a BG to get to 1-1.5lbs? and how long till their 3-4lbs? Which on fights better? I truly dont know YET. Of course this depends on if you can catch them. So if i leave out the aggressive BG maybe the tilapia will be catchable. If not I'll stock the BG. And lastly at the risk of being black-balled from the forum, I truly prefer the taste of tilapia to BG. And I've eaten lots of both. Unfortunatly The best part, the data table i cant paste because it doesn't make sense but I'll give you the bottom line. From what I see
that if you stock LMB on the very heavy side with tilapia that you get FANTASTIC growth of both species, the Bass growth is in the first thread. In the pond they put the 494 bass in the tilapia growth was this: 590 brood tilapia- 150grams/ea=5.2oz and 6mths later avg harvest wght was 475 grams=1.04lbs, ranging from 182-650 grams. largest at 1.4lbs. with >20,000 juveniles. total unexploited juvenile biomass at harvest was 376kg=828lbs and total tilapia biomass was 655kg=1444lbs


POLYCULTURE OF LARGEMOUTH BASS (Micropterus salmoides)
WITH BLUE TILAPIA (Oreochromis aurea):
USING TILAPIA PROGENY AS FORAGE
William A. Wurtsa, D. Allen Davisb, Edwin H. Robinsonc
aCooperative Extension Program, Kentucky State University, P. O. Box 469, Princeton, KY 42445
bUniversity of Texas at Port Aransas, Port Aransas, TX 78373
cMississippi State University, Delta Branch Experiment Station, P. O. Box 197, Stoneville, MS 38766

1. Introduction
The proliferation of tilapia in public waters, their ability to reproduce rapidly and
their acceptance as forage by piscivores have generated interest in the use of largemouth
bass to manage tilapia reproduction and proliferation. Research by Schramm and Zale
(1985) indicated that largemouth bass (Micropterus salmoides) show a preference for
blue tilapia (Oreochromis aurea) over indigenous forage; this was dependent upon forage
size and availability as well as vegetative cover. Swingle (1960, 1966) examined the
ability of largemouth bass and peacock bass to utilize tilapia spawned in tilapia
production ponds. The addition of piscivorous predators reduced the total number of
tilapia (juveniles) while increasing the number of harvestable (large) tilapia.
The present study was designed to evaluate the use of largemouth bass to control
tilapia reproduction as well as to provide base-line information concerning the number of
bass that can be supported by the progeny of a fixed density of tilapia broodfish.

2. Materials and Methods
Five 0.04-ha ponds were stocked with largemouth bass fingerlings at the
following densities: 124, 247, 494, 988, and 1136 fish/ha. The mean weight of
individual fish stocked at densities of 124-988/ha was 17.3 g; 60.6 g bass were used at the
1136/ha density. Tilapia broodfish (150 g) were sexed and stocked at a density of 590/ha
and a ratio of one male to three females; 340 g broodfish were stocked with the 60.6 g
bass. Additionally, each pond was stocked with crawfish (Procambarus spp), 45 kg/ha,
and top minnows (Gambusia affinis), 30 kg/ha, to provide forage until juvenile tilapia
populations had become established.
A 32% protein, floating catfish feed was offered for the first three weeks of the
experiment at a daily rate of 14.4 kg/ha to provide nutrients for tilapia broodfish and to
stimulate natural pond productivity. After three weeks, feed was offered at a fixed daily
allotment of 7.2 kg/ha until water temperature fell consistently below 15° C (the first
week of November 1985). Fish were stocked 14 June 1985 and harvested from 17 to 21
December 1985.
Temperature and dissolved oxygen levels were measured in each pond three times
weekly. No supplemental aeration was used. Well water was pumped into ponds
continuously when freeze warnings were in effect to protect tilapia from low water
temperatures. Since it was presumed that tilapia activity in the bottom sediments would
affect turbidity, secchi disc measurements were initiated after tilapia populations were
well established, approximately 3 months after stocking, and continued once weekly to
assess water clarity. These data were intended as an indicator of visibility as encountered
by the bass.
At harvest, individual weights, total biomass and survival of bass were
determined. The gut contents of bass were examined to determine if they were
consuming tilapia. Final biomass of the original tilapia broodfish and total biomass of
unexploited juvenile tilapia were measured. Mean individual weights of tilapia broodfish
were calculated by weighing the largest tilapia harvested from each treatment, equal in
number to tilapia broodfish stocked. Broodfish survival was assumed to be 100% in each
treatment. No mortalities were observed among broodfish during the course of the
experiment.
Final weights of bass and secchi disc measurements among stocking densities
were compared using one-way analysis of variance and multiple comparison tests. Data
means were compared using Scheffe’s test for data sets of unequal size and Duncan’s
multiple range test for data sets of equal size (Ott, 1977). Results are reported significant
with p set at the α ≤0.05 level for both one-way analysis of variance and multiple
comparison tests. The correlation coefficient, R2, is reported for significant, analysis of
variance findings.
3
3. Results
The data presented in Table 1 indicate that, at harvest (Figure 1), bass in the high
density ponds (988 and 1136 bass/ha) were significantly smaller (R2 = 0.894) than those
in low density ponds (124, 247, and 494/ha). Bass from the highest density pond had the
highest survival (Table 1). Bass mortalities were observed during the first seven days
following stocking. Gut contents of these fish revealed no food items.

Harvest weights of individual tilapia broodfish were greater in ponds stocked with
high bass densities. Broodfish weights were similar in ponds stocked with bass densities
of 124-494/ha (Table 2). Total tilapia biomass ranged from 655 to 907 kg/ha in low
density bass ponds and from 442 to 840 kg/ha in high density bass ponds (Table 2).
Numbers and biomass of unexploited tilapia were comparatively larger in low density
bass ponds than in high density ponds (Table 2). In addition to many big juveniles, ponds
stocked with bass densities at or below 494/ha had several kg of tilapia fry (819/kg).
Each kilogram represented approximately 20,000 fry/ha.
Dissolved oxygen concentrations and temperatures ranged from 2.8 to 15.0 mg/1 and 8°
to 31° C (Table 3). Secchi disc measurements were from 24 to 117 cm. Throughout the
growing season, mean seechi disc values were significantly higher (R2 = 0.65) in high
density bass ponds (Table 3). The high density ponds had substantial filamentous algae
blooms.

4. Discussion
In certain situations, tilapia have been shown to be an important source of forage
for largemouth bass (Noble et al., 1975; Schramm and Zale, 1985). No tilapia or other
food items were found in the stomachs of bass in this study. Presumably, this resulted
from reduced intake in response to the 28-day period of cold weather preceding harvest.
It appears that tilapia were consumed as is evidenced by the low densities of unexploited
(juvenile) tilapia in high density bass ponds (Table 2). Ponds stocked with high densities
of bass, which produced significantly smaller bass at harvest (Figure 1, Table 1),
apparently did not have a sufficient forage base for optimum bass growth. Tilapia
broodfish in ponds stocked with low bass densities were substantially smaller at harvest
than broodfish in ponds with high bass densities. The tilapia-bass interactions observed
in this study, with respect to number and size of tilapia at harvest, are similar to those (as
discussed in the introduction) reported by Swingle (1960).
Since multiple spawns would be expected from tilapia broodfish and sexually
mature offspring, ponds stocked with a fixed number of tilapia broodfish should supply a
relatively stable forage base. The bass population that could be supported by a tilapia
based forage system would depend on the rate of forage production (spawning) and the
rate of forage consumption (predation). That is, a given number of bass should be
capable of controlling the spawn of a given number of tilapia.
One might be tempted to define these interactions with Swingle’s (1950) F/C
(forage biomass/carnivore biomass) ratio. However, that relationship does not apply well
in this example. It is the total spawn (tilapia juveniles) and therefore, the original density
of female tilapia broodfish that is important. To avoid confusion, the tilapia-bass
relationship in this study will be represented as the ratio of female forage broodfish (FB)
to piscivore (P) densities (FB/P).
The optimum FB/P value is dependent upon production goals. If one’s objective
is to produce large tilapia and to reduce or eliminate unwanted spawn, bass should be
stocked at high density. If bass size is to be maximized, bass should be stocked at low
density. The results of this study suggest that a FB/P ratio of 1.4 is adequate for
production of large bass. Values near 0.7 would produce large tilapia and minimize
spawn.
Based on the results of this study, it seems feasible to maintain tilapia/bass ratios
for one production cycle in a temperate climate. Tilapia could be marketed as a food fish
crop. Bass harvested from such a system could be used for management of sport and
recreational fisheries. The technique of culturing predatory fish with a prolific forage
species has potential for other game fish, particularly species of high economic value and
whose food requirements are not readily satisfied with commercial feeds