Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations The 14 Year Tilapia Conundrum

Goals: 1. self-sustaining Tilapia Population In pond.
2. Occasionally observe signs of the size & health of the population.

The Pond: 3 2/3-acre(surrounded by 10 homes) 30+ year old retention pond in Northeast FL. The pond has little to no structure & the only shelter is weeds along the bank & here & there in the center of the pond. The water is a murky green brown with visibility ending at 3 feet. The average depth is about 7-8 feet & maximum depth at approximately 12 feet. The water level is very stabile throughout the year. The pond’s original populations include LMB, CNBG, CGC, RES, MF, Eels, Br. Catfish, Bowfin, snails, mussels, clams, crayfish, shad, gold shiners. Regular visitors include River Otter, GBH, Anhinga, Osprey, Muscovy ducks & Canada Geese. In varying years TGC, & TP were added to the pond. Six-foot gators routinely take up residence & are eventually eliminated by the county gator trapper.
The 14-year Tilapia history: I have never seen the signs of a Tilapia weather kill. Never seen a school of Tilapia swimming in the warm shallows or warm surface water. Never seen an occasional Tilapia swimming near the bank. I have never caught a Tilapia, but never fished for one either. Never seen a male & female on a spawning bed. I have seen 2-3 Bull Tilapia 20+ inches on spawning beds in the warm shallows in the early Spring but never with or courting a female. The males display & chase each other away from their territory. Once the water warms, they disappear not to be seen again till the next early Spring. I have only observed one dead Tilapia, 23+ inches, old age I suppose. The buzzards quickly found him & feasted. This winter has been exceptionally warm, I have not seen these large tilapia on their beds ? This area of Florida has wild self-sustaining tilapia populations in some public ponds. How they got there no one is talking.

Past Tilapia Stockings:
Year # Size
09 300 2-3”
10 50 3-4”
11 600 2-3”
12 600 2-3”
13 400 2-3”
20 400 4-6”
21 400 4-6”

Except the “50” from Texas, all the fish were from a local fish farm managed & owned by an emeritus professor (fish were his specialty) & his family. It seemed to me that over the years with just a few mature fish surviving, I would have a noticeable population. I certainly though the larger fish would make a difference, although everything has remained the same. I thought they 4-6” were big enough to evade predators & soon begin reproducing. I do not see any change in the LMB either. I have not done relative weights.
I am not going to electro-fish. If I spend $ on anything it will be for more 4-6” Tilapia.

The answer is: ??
All is probably normal for your area. They are reclusive & you will very rarely see any of them. All are on the bottom out in the middle of the pond doing their thing. Just chill.

You have never stocked enough for your pond size & # of predators in any one year. Reduce predators & then stock X amount in any one season.

You have one particular problem that you have not addressed & it is _____.

Your comments & suggestions are much appreciated.

I'm interested to hear what everyone thinks.

One thing you didn't mention (if you did I missed it).. Has the state of aquatic vegetation shifted any???
Pretty sure a 15" LMB would consume a 4" TP, maybe even a 5".
My personal opinion is that you have strong natural predators. Every year will be different in growth and numbers as well as the type and amount of aquatic veggies. TP can change the algal structure which can affect other species as well.
My 2 cents... sounds like a well balanced system to me.

Answer:

Stock at least 26# of tilapia in each pond, and make sure that they are between 1/3 to 1/2 the size of the largest LMB in there. Stock pure blue Tilapia, not hybrids, because the hybrid tilapia will have offspring that are mostly male - NOT what you want for long term reproduction. Talk to the "emeritus professor" and ask him what species Tilapia were stocked. If he says a hybrid, ask him about their reproduction numbers and what percentage of Male/Female Tilapia come from that spawn.

A Largemouth Bass can and WILL eat Tilapia up to about 1/3 their body length, maybe a wee bit longer if they are hungry enough. The Gators and Otters can eat the biggest Tilapia that are in there, so your only option is to stock enough that are large enough to evade getting eaten by the Bass to at least pull off 1 spawn before they get eaten by something else.

What is the bottom habitat like? Muck/mud, Clay, sand or pea gravel? If the first two, put 6" thick pea gravel in 1'-3' deep areas that are about 4'x6'. As you have observed, only one male will make a nest in that area. I would put down some Geotextile fabric first so the pea gravel doesn't disappear into the mud/muck. If you have sand, they will use that to make beds on.

There has not been much change in the aquatic vegetation since I stocked the Grass Carp following state wildlife recommendations per acre (15 TGC 60 total). Till they died off the bottom was bare. I only stock 6-10 total as needed now & I am happy with the weed control. I have not noticed any change after stocking the TP. The murky green color & much reduced visibility is something new the past few years. It is very interesting how the pond & populations have changed. Bowfin & Brown Cats have been removed or under control. My thoughts that this summer would be one to remove as many remaining Cats as I could. Although, I have not seen a black ball of just hatched catfish near a bank in years. In the beginning it was a routine thing to see in the spring. Thank you for your thoughts.

Do a seine survey.

Geotextile fabric, What is the best style & weight? Mat or woven? I have looked on-line & see fabric in a 2oz to 8oz range. I only want to do it once & have it last but I do not want to worthlessly over spend. Anything I do to the pond is for fun & amusement it is not an I have to thing. The closest I can get a gravel load dumped is 200 ft from the pond. All the rest is hand & back work. Wish I had thought of the geotextile barrier when I tried to do BG beds long ago. Gravel has sunk into the sand & clay.

The beds, in water how deep?

I have read about people doing seine surveys. How big must the net be to be effective?

Two bull tilapia are back & challenging one another. No females have been seen as usual.

Maybe rent a tractor with a front end loader.

No wonder they are fighting!

I agree with Theo about the tractor.

I can get a 32hp JD or Kubota with FEL (and trailer) for $200/day in my area - including the taxes and damages waiver.

If you do a Friday afternoon rental, then you can have the equipment until first thing Monday morning for a 1-day fee. (If you don't go over 8 hours on the meter.)

I love that deal on jobs where I work the equipment for a stretch, then work by hand, then back to equipment.