Pond Boss Forums STOCKING A NEW POND Raising Forage and Bait Gambusia On - err, Under - Ice

I am conducting an experiment this Winter to see how Gambusia will fare through a Central Ohio Winter. Two of the most common negative thoughts on the Gam's chances of making it through a cold Winter - 1) deprived of their ability to leap out of the water and escape hungry mouths, they will be eliminated by predation under ice cover, and 2) they will be killed by low temperatures - will be examined.

I have Gams in three different BOW this Winter, my 1/2 acre new pond (where 100 Gams stocked in June produced 100's of thousands to millions of offspring by Fall), my 1 acre established pond (where about 500 Gams transferred from the new pond during the Summer produced a smaller number of offspring, that nonetheless could be found in the shallows around the entire perimeter by Fall), and a 100 gallon horse trough (which had about 30 Gams put in it in early Fall).

These three locations have vastly differing levels of predation. In the new pond, the largest number of Gams face a small number of predators (a little over 300 total YP, SMB, RES, and BG, plus a lonely Walleye). The middlin' number of Gams in the big pond have a much bleaker outlook, being faced with well established populations of LMB, HSB, CC, BG, and RES. The 30 Gams in the horse trough have no predators to worry about at all.
Obviously, final results will not be known until Spring. I suspect the Gams in the big pond will likely be gone by then, but I think the species will still be present in the new Pond next year (is there any way 300-some small predators can eat what must be well over 1000 Gams apiece over the Winter?).

I do have some preliminary results on the question of Gams' cold-water survival abilities. We have had ice on the ponds for about 10 days now, and active Gams can be seen where the edge of the ice melts at the shoreline of the new pond on sunny afternoons. In addition, I forgot to plug the tank heater in the horse trough in one night this last week, and the Gams in it survived temperatures cold enough to put an inch of ice on the top and sides of the trough - the water temp must have been 32 degrees.

NOTE: These Gams, of a species not listed by the source, but described as "Winter hardy", are one of many species of Gambusia found throughout the country. Other species, native to southern climes, would undoubtedly have a harder time surviving in cold water.

Interesting experiement, Theo. I know your predator fish will feed during the winter, but you'd think the gams have a chance with the slower metabolism of the predators. That is, if they can survive the cold water.

They thrive in the shallows even in our hot South Texas summers. There's no telling what the water temps can be mid-day in 1' of water or less when the air temps are well over 100. They're hardy little guys.

Neat study. Info on the source would be good. It is not short term cold usually that kills the fish but extended time ( week +-) below there thermal limits. The limit is usually several degrees warmer than their lethal minimum. For example tilapia start the process of dying (cold ,stiff , lethargic swimming) about 5 degrees above their thermal minimum and stay that way for a week or so as the temp continues to drop. By the time they succumb the temp has reached the thermal minimum.

SRAC Tilapia

The intolerance of tilapia to low

temperatures is a serious constraint

for commercial culture in temperate

regions. The lower lethal temperature

for most species is 50 to 52o F

for a few days, but the Blue tilapia

tolerates temperatures to about

48o F.

Tilapia generally stop feeding when

water temperature falls below 63o F.

Disease-induced mortality after handling

seriously constrains sampling,

harvest and transport below 65o F.

Reproduction is best at water temperatures

higher than 80o F and does

not occur below 68o F. In subtropical

regions with a cool season, the number

of fry produced will decrease

when daily water temperature averages

less than 75o F.

Theo,

Back in the day we used to get ice thick enough to walk across the ponds at least once every year. Our southern gams survived well. I'm betting your more adapted subspecies won't have a problem at all. All bets are off if we have an unusually long string of days in the teens or lower.

Jones Fish

It always amazes me to see the prices that people get for those little guys.

I guess that makes me a millionaire.

Well you're sitting on a gold mine, Trebek!

IME they are only moderately hardy in cold temps. Some make it, most don't. But it really doesn't matter because before long you have hundreds again.

I haven't seen any Gams in the ponds during the brief periods they have been ice-free in the last month. But the Gams in the watering trough are still swimming around AOK.

Theo, How much daily variation of water temperature does the heated water trough have during days with temps in the single digits?

I've never had a thermometer on it, Bill, so I can't be certain. Normally "not frozen" is all the temp data we need.

When it's really cold, like the night before last, there will be some ice up on the rim of the water level. The heating element is probably working full blast to try and keep the water at "40 deg F" then. Other than times like that, is should stay fairly constant if the air temp is, say, between 15 and 40.

I did have it unplugged for a night (or two?) and it got 1"-2" of ice all around the sides and on the top. That was probably the most variation there has been this Winter (downward, anyway).

After a few days of warm temps and rain, the ice on my ponds was down to a very unsafe-looking thin layer, melted at the edges, yesterday. In the new pond (with the most Gams and the fewest predators), Gams were cavorting at the surface next to the ice. I saw 2 of them swim in 1/4" of water over the ice for a while.

Gams are a hearty bunch that is for sure. Their reproduction rate is off the charts, makes rabbits look like monks.

Oh and why no photos Mr. Moderator???

We have had almost 6 weeks of ice cover on the pond. After 2-3 warm days, it is thin at the edges. I saw 30-40 Gams active under thin ice in shallow water this afternoon.

Thanks for the update, Theo. Any news on the water trough gams?

I have not seen them at a glance for a couple of weeks (poor lighting at times I was at the barn). I strongly suspect they are OK, however.

I think you will be pleasantly surprised at how many pull through the winter, even under heavy predation... By July there will be so many in your pond you'll wonder if they ever stopped breeding during the winter!

Theo will probably retire selling them as "Northern Cold Tolerant Gambusia" Just think Theo, you could quit farming!!!!

You guys have me interested in these GAMS. Presently I have stocked my pond with golden shiners and fhm. I wonder if they would be a good addition to my S.Mich farm pond. I know that they are marketed as big time mosquito larvae eaters. I could over winter some of them in my greenhouse aquaponics system for the next year's brood stock. I also have a good sized drainage ditch that I was thinking of damming up for the propagation of some fatheads, and I could allow the gams to get started unmolested in there if the fhm and the gams would get along??

IME FHM will do okay with Gambusia in the same pond - IMO FHM numbers are somewhat lower than they would be without the Gams (prresumably due to egg predation).

Whether I would use them in a pond depends on what species I am going to manage it for. Gams are IMHO good for feeding small mouths (BG, YP), but I would probably not use then as initial forage if managing for large predators. GSH, for example, are a better choice there.


If I did really well at it financially, maybe I could afford to continue farming.


Live Gams sighted in the trough yesterday.

Theo:

They should pull thru the winter just fine. I had Jones deliver a dozen 2 years ago along with some other fish, and I put them in a 100 gal trough that I was using as a small pond by the house - no other fish in it.

I plugged in the heater just enough to keep the ice off of an area about 1' in diameter every other day during the winter last year (2007/2008) and they were still there in the spring. I upgraded to a 300 gallon one this winter, above ground level but surrounded with dirt, and have plans to run it down to the 100 gallon one this year (that'll be buried in the ground)via a man made "stream" and circulate the water back up with a koi pond pump/filter.

Remember, gambusia are native as fart north as central Illinois in the Midwest and Maryland on the east coast... They are pretty darn cold tolerant. They have done well for 20 plus years in a 2.5 acre pond in the mountains of central PA under heavy predation.

Michfish, you may be able to get them to overwinter in your pond without any special things being done. I realize central PA is not southern Michigan, but the weather isn't too far off.

I think gambusia give bass a good jump start in life. Often times when other species fry has outgrown the mouth size of young bass, there is a ready supply of gambusia babies ready and waiting to be eaten!

I have numerous sources of gambusia. If anyone wants to try some, if you are willing to pay the costs to ship a few your way when the weather warms I don't have any issue rounding some up for you... Just let me know!

They are hardy when it comes to transporting... Before 9/11 I remember catching some spotted gambusia (never seen one check this link http://www.aquabid.com/cgi-bin/auction/auction.cgi?fwlivebearersw&1234502416 )and putting them in a small tupperware container and flying them back with me from FL. They survived the flight just fine!

Thanks for the offer. I'll probably get back with you when the weather mellows a bit. It's 55 degrees and raining here today. Very strange. And I just finished building my ice shanty????
My surface water fed pond is far over its banks and is making me nervous. At least there is nowhere to overflow but on my own property. The drain is working but not as fast as it is coming in!! I planted 60 pounds of fhm last fall and I hope to see sings of them still being around. Are the gams really better at eating mosquito larvae than the other fish and minnows in my pond?

Probably not. Darn near every fish eats mosquito larvae when small.