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Caught this little tilapia this morning-about three inches long. I haven't stocked any this spring 2011. It tells me two things-some are still in there and obviously they are spawning. Has anyone seen this occur this far north? thanks
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Last winter was very mild, doesn't suprise me...
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I have not heard of anyone that far north having over wintering unless they have springs. That can cause a real problem with carrying capicity.
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I just hope that some are getting adjusted/evolving an ability to withstand cooler conditions. How nice would it be to have full time Talapia in the north? IIRC some Eel grass was originally only native so of the Ohio river but thru the yrs (and I believe Bill Codys coaxing) it is now doing well up here.
CODY note: The eel grass that Bob-O refers to above is not the standard eel grass aka Valisneria americana . The eel grass I am working with is corkscrew or spiral eel grass a southern variety or subspecies adapted to warmer water, although it will survive much further north and in colder water than tilapia.
Last edited by Bill Cody; 09/28/12 09:08 PM.
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If they are overwintering it may cause a problem especially if any get out of the ponds and in other sources of water.
I think that is the fear most places try to put on us.
I am sure mine will not have a chance as my ponds are not that deep, do not have springs or wells tied to them.
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Last winter was very mild, doesn't suprise me... I'm pretty sure that is it. Nothing to be concerned about as a continuous problem year after year. That is unless mild winters will be the norm, which I doubt.
Last edited by Cecil Baird1; 08/27/12 11:14 PM.
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A few over wintering tilapia can fill up a pond and cause extreme biomass problems. One reason they work well is they don't over winter. If 75% of your carrying capacity is tied up in tilapia you might not like that very much.
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I just hope that some are getting adjusted/evolving an ability to withstand cooler conditions. How nice would it be to have full time Talapia in the north? IIRC some Eel grass was originally only native so of the Ohio river but thru the yrs (and I believe Bill Codys coaxing) it is now doing well up here. This would be horrible! Might result in tilapia being banned in more states than they are already.
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Caught 4 more last night about 6 inches long.
dentist by day pondboss by night
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Eat'em before it gets to cold or they overpopulate
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I missed this thread......Tilapia are the oldest recorded farmed fish...in over 6000 years, they have never acclimated to cooler climates. Also, reproduction in overwintering tilapia will rarely occur in northern latitudes due to a short photo-period.
As a side note to what ewest mentioned about tilapia taking up carrying capacity...what is often forgotten is that with tilapia consuming normally non-utilized nutrients in the pond, the "carrying capacity is drastically raised....generally, tilapia are ignored for carrying capacity concerns.
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I missed this thread......Tilapia are the oldest recorded farmed fish...in over 6000 years, they have never acclimated to cooler climates. Also, reproduction in overwintering tilapia will rarely occur in northern latitudes due to a short photo-period.
As a side note to what ewest mentioned about tilapia taking up carrying capacity...what is often forgotten is that with tilapia consuming normally non-utilized nutrients in the pond, the "carrying capacity is drastically raised....generally, tilapia are ignored for carrying capacity concerns. Unless you're pushing things in a non-aerated pond during the summer....... Then I believe they should be considered part of the carrying capacity because they need DO too!
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esshup, Do you think they need as much DO as the regular pond fish? I've only been around these fish the last three years and I still learn something new about them every day. Us old dogs can learn new tricks every once in a while .
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Rex???? A little help here! I know that the ones that we raised in a RAS over the winter went off feed if there wasn't enough aeration. I didn't have an O2 tester, but the other water parameters were O.K.
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I've had thoughts along a similar line. I don't know the first thing about Tilapia, other than I don't want them competing with my BG, but if they reproduce like gangbusters and eat FA....isn't the FA introducing or elevating the DO content to some degree?
It almost sounds like adding the initial brooders (the same as adding any other fish) will impact the biomass of the BOW immediately, then as reproduction takes hold and their numbers increase, AND they aggressively target the oxygen producing FA, the carrying capacity of the pond will be reduced?
What am I missing? Is it a case of having the Tilapia die out over winter and hoping that they don't contribute to eating themselves out of DO before they expire?
If stocked together with GC in an unaerated smaller BOW, is there cause for concern regarding too drastic reduction of aquatic growth, resulting in reduced DO available for the other fish species present?
"Forget pounds and ounces, I'm figuring displacement!"
If we accept that: MBG(+)FGSF(=)HBG(F1) And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1) Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT? PB answer: It depends.
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I have seen about 6 in the 8 inch category in the last few days. I guess they are moving to the warmer shallows during the day now.
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I hope to get out soon and see if mine are moving into shallow water yet and if any vegetation has come back. Pond seems clean this year.
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sprkplug, yes the FA makes O2, but I'll bet that if a study was done (ewest, has one?) you'd find that the majority of DO that is in a pond is "produced" by two things - the interaction between the pond surface and the air, and phytoplankton (i.e. "the bloom").
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There are three main sources of oxygen in the aquatic environment: 1) direct diffusion from the atmosphere; 2) wind and wave action; and 3) photosynthesis. Of these, photosynthesis by aquatic plants and phytoplankton is the most important. Oxygen, derived from photosynthesis, is produced during the day when sunlight shines on the plants in the water. Oxygen levels drop at night because of respiration by plants and animals, including fish. These predictable changes in DO that occur every 24 hours are called the diurnal oxygen cycle
Aquaculture of Tilapia and Pangasius; A Comparative Assessment
Michael V. McGee, PhD Caribe Fisheries Inc. Lajas, PR
Tilapia can survive exposure to as little as 0.6 mg / L D.O. for short periods of time and levels of 2.0 mg/ L are adequate to prevent significant stress. However, chronic exposure to D.O. levels below 3.0 mg/L will compromise feed utilization and growth rates as well as disease resistance. Thus, Tilapia are dependent on dissolved oxygen in water. Under conditions of intensive production Tilapia ponds are aerated to increase or sustain dissolved oxygen levels. Although effective, use of mechanical aeration can significantly increase production costs.
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So theoretically speaking, is it a plausible assumption that an herbivorous fish species of high fecundity, like Tilapia, might negatively impact their environment in regards to DO production?
Particularly if exacerbating circumstances existed, such as in a small, unaerated, shallow BOW, or perhaps when stocked together with another herbivorous species, (GC)? Or if the Tilapia were to overwinter?
I realize the chances of such an occurence may be miniscule, but does the potential exist?
I've wondered this for some time.
"Forget pounds and ounces, I'm figuring displacement!"
If we accept that: MBG(+)FGSF(=)HBG(F1) And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1) Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT? PB answer: It depends.
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I put some in a 1/4 pond so maybe we will se how they do in a small body of water. I am sure that none will overwinter here but you never know. If I decide not to add them next year we may find out if some did. But I think even if the water did not get cold enough to kill them, it would slow them down enough to be eaten by either the LMB or CC.
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Any water system with plants and or animals has the potential for BOD to be more than supply. The more living organisms and the more static the water the higher the chance. That is the exact reason overwintering tilapia can be a problem (to much biomass - BOD - for the available supply). It is simple - a water system is like a car engine - you can run it a long time at low RPM but if you run it at high RPM it is likely to break sooner.
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That's what I thought. Thanks Ewest.
"Forget pounds and ounces, I'm figuring displacement!"
If we accept that: MBG(+)FGSF(=)HBG(F1) And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1) Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT? PB answer: It depends.
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The following is all based on tilapia in a "typical" sport fishing BOW, and NOT overwintering...
This thread personifies why so many states classify Tilapia as an "invasive"..State biologists like to look at the papers, and deduce that Tilapia compete directly with every native species in a pond's ecosystem, so they are banned without further thought and ignoring real world proof. In the pond (where annual death of tilapia is a near certainty), the paper theories dissolve and leave the paper pushers scratching their heads in bewilderment, because every species that SHOULD be displaced (on paper) thrives.
Just some of the almost countless benefits to a pond is when tilapia aerate a pond to "farm" bacteria and Macrophytes, which become a "new" food source that would not otherwise exist absent tilapia. Tilapia fry/fingerlings also become the primary prey, greatly reducing pressure on "native" prey. Tilapia primarily only consume plants and nutrients no "native" specie can (thus, they are neither a load nor consideration on the "normal" carrying capacity or BOD). Tilapia DRASTICALLY increase water quality by increasing aerated water, aerobic bacteria and by reducing the toxins, such as hydrogen sulfides formed by anaerobic bacterias.
Stockings of 100 pounds, or more, per surface acre have yet to be shown detrimental in any pond or lake I am aware of. SEPM actually suggests stocking Tilapia at 100 pounds (or more) per surface acre in trophy bass waters on their website.
The fears and worries mentioned in this thread "seem" logical, yet the way tilapia function in water, not on paper, makes the fears a non issue.
In a sport fishing pond, consider Tilapia as adding a supplemental feed program, aeration and as a nuisance plant eradication program and NOT as a "Fish". And in the same way as supplemental feed and aeration create an "unnatural" increase in a BOW's carrying capacity, so will annual use of Tilapia...after 3 years of adding tilapia, the BOW will have a far higher carrying capacity (NOT including the tilapia weight).
Extremely little scientific study has been done on tilapia in a pond setting as we use Tilapia, and that is outside of the food fish production industry. From what I have seen in ponds, Tilapia seem to be somewhat self-limiting through cannibalism, from being so territorial and aggressive toward each other....they virtually ignore other species, even when nesting. I think Bob Lusk would agree, tilapia seem to defy all the rules other fish play by.
Tilapia, in short are not a burden on a carrying capaicity in a pond, they are a missing link in our waters that bring out a ponds true carrying capacity capabilty Without adding Tilapia in the weight, and after 3 years use, probably at a level at least 2-3 times higher....all with no effort other than writing the check to cover annual stocking...
Last edited by Rainman; 10/06/12 04:48 PM.
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How in the dickens can a tilapia increase aerated water?
It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.
Without a sense of urgency, Nothing ever gets done.
Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP
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