Pond Boss Forums MANAGING AN EXISTING POND Corrective stocking In need of more predation

Hey guys, been a while
I've got a shallow 3/4 acre pond in WI, currently running a 4 diffuser aerator. I have established populations of YP, GSF, and LMB; theoretically there should still be PKS but I have not seen them in a while. GSF between 4 and 6 inches have dominated the catches and I have seen smaller in the water. YP are present, I have caught 3 this year 8-8.5 inches. The only LMB I have seen were less than 2 inches and a single 7in individual that was rather thin. So basically I am worried that I need a predator to cut down on the GSF numbers, normally I would suspect they are stunted but their body condition is rather good. The LMB recruitment I am seeing suggests a decent population of adult fish, but I have not seen one in a long time. The poor body condition of the one bass I have caught this year suggests that I need to make some changes.
The other problem I have is too much chara and duck weed, but I already have a possible solution in the works. Namely a KASCO Marine AquatiClear Water Circulator - 1hp, which I already have but the power is not yet wired so it is not installed yet. The idea here is to move a little water so the chara cannot grow to the surface and the duckweed can't sit on top of it. I also am hoping that it can help dig the pond out a little bit as I could use some more depth.
Here is where I want some input;
1. Should I stock say 20# of fatheads in fall to bump the growth/health of the bass?
2. Should I stock a new predator to temporarily deal with the small sunfish?
3. If I want to sample the fish in a more effective way than hook and line, should I get a seine or fyke net?
My brainstorming for a predator is to stock either WE or CC. I understand that WE working is a long shot but I like that they absolutely cannot reproduce and become a problem. Also I kinda hope that my artificial current could help them survive summer, although my pond does not heat up that much. I have had CC in the past before a recent fish kill so I know they would survive, but I am not sure they would help as much as they are not as big of piscivores as WE. I am not too fussed if the WE do not work, and I would really like to find a source of Saugeye but what do you guys think?

I am the primary predator of our GSF. It seems to me that you, too, could be an effective reducer of the splendid GSF.

If I believe there's an imbalance between BG and GSF, I sit on the dock for and hour or two and haul them in. Some times it's GSF; other times it's BG. I chum a little to get them coming, then start with a double or triple hook rig on an ultralight spin or a 3 weight fly rod. Baits can be Berkeley Gulp or Powerbait grubs, crappie nibbles, earthworms, Creme trout worms, or nearly any other small rubber type baits. For me it's usual to hook 2 and often 3 sunfish on each cast. My water clarity is good, so I can sight fish for individuals that I'd like to remove.

At this rate you could pull 100, 200, 300 or more GSF out each week and reduce their population quickly.

Fyke nets are useful.

That scrawny bass actually indicates nothing except it hasn't been eating well or digesting its food. It seems there should be many many GSF fry and fingerlings for nearly all the bass in your pond. The opposite predation might also be occuring. The GSF may be gobbling up your young bass, limiting bass recruitment. A very good bait for big GSF in my pond is a 3" to 5" LMB.
I have no experience with WE nor CC in my pond. They both feed at night when YP and GSF tend to be motionless on the bottom so are easy targets.

The fatheads will feed the GSF. Stock Saugeye. They predate more on panfish than YP, WE are just the opposite.

If you could find 6" LMB to stock that would be an option too. 75 of them.

GSF population is predominantly between the sizes of 4" and 6". Maybe an average of 5".

So I think what is missing is enough forage at much smaller lengths. Keep this in mind. A 6" GSF is every bit as heavy as a poor conditioned 7" LMB. They are competing with little bass and have the advantage of being able to make better use of invertebrate prey as well. There are WAY TOO MANY 4"-6" GSF.

Sure the GSF are spawning but there aren't enough 1/2" to 3" GSF because there are WAY TOO MANY 4" to 6" GSF. They are cannibalizing their YOY.

IMHO, the OP needs to remove 4" to 6" GSF from the pond so that GSF YOY have better survival so the YOY can feed the LMB enough to grow well. Thinning some GSF will help the GSF grow better too.

This pond is forage locked in a sense. The populations are high and there is very little recruitment. Most of biomass is tied up in prey fish that are too big for the LMB to eat.

4Corners has good points. Abundant GSF can heavily reduce recruitment of LMB by eating eggs and fry. GSF have big mouths to eat big things for the fish's size. GSF are aggressive. I deal with GSF in a YP test feeding small pond. GSF like to hide in shallow shoreline habitats often making it hard for predators to capture them. GSF can be prolific and thrive living in rocky shoreline areas. For me GSF will readily enter unbaited minnow traps and fish traps with larger funnel openings. I can easily get 15-30 in each trap set. I'm trapping them daily now with lots of YOY GSF in the traps.. Strongly reduce GSF numbers before adding LMB unless you can add LMB big enough to right away eating GSF. But without strongly reducing the GSF the GSF will hinder reproduction success of LMB by eating eggs and fry. Walleye in my experience are not good predaors of GSF.

Thanks for the input guys,
Esshup, I really want to add saugeye, but I am not aware of a source that I can buy from to get them in WI or shipped to WI.
As far as harvesting out GSF, how many should I aim for and is there a relative weight chart for them for me to better track their body condition? I really wish I knew what my upper end LMB was so I could know if they can predate GSF but they have thus far eluded me. I am also hesitant to stock more bass as I am still seeing evidence of recruitment. I will try removing some GSF but I can only catch 1 or 2 at a time before they spook.

I was going to reply that you would probably be the best predator on GSF, but 4Corners already put up a good post on that.

In ponds with abundant GSF, I find them to be both aggressive AND easy to catch. That is a perfect combination for you to make a dent.

Do you have any kids, grandkids, local Boy Scouts that can help you fish? Most kids love catching tons of 5-6" GSF.

When you say you only catch 1-2 at a time is that on artificial lures or live bait?

In Kansas, my solution would be put 8-10 cedars trees with a cinder block around the pond in 3-5' deep water. Have kids fish with worms on a small hook under a bobber. The cedars act a "fish concentrators". I have had kids catch over 20 from a single tree (plus a few BG), and then we move on to the next tree for more.

Do you have any "fluffy" cover in the pond to concentrate the smaller fish? Do you have any heavier cover with open spaces in between? LMB need the latter as "ambush cover" to dine happily. They use up much less energy if they can just hide behind a tree trunk and then suck up a clueless panfish as it wanders past.

Good luck improving your fish populations. That should be an enjoyable problem to undertake!

My lures of choice have been 2 in paddle tails, 1 inch powerbait minnows, small flies, etc. Nothing has been super effective except when I used minnows at dusk, so live bait might be the ticket. As far as "fluffy" cover, that is a current issue with the pond. As I illuded to earlier the pond is basically weed choked, although I have a solution that is going in within a week barring hang-ups. I am not aware to what degree "too much" cover would restrict LMB feeding causing increased sunfish numbers/ decreased body condition, but I imagine it is possible. Could removing a large portion of this cover decrease sunfish numbers from increased predation? Not sure, but as it stands the pond is 95% covered in thick chara, only the aerators and a few random spots are open.

Yes, more open water will allow for more predation.

The standard reference (Wiley et.al 1984) for amount of plant cover in ponds for best or optimum (100%) all natural bass and sunfish production is to have 36%-40% maximum plant cover in the shallow areas aka littoral zone. The deep pond basin having no weeds. Weeds just around the shoreline areas maybe down to 5-6ft. . Fish production was still high with 80% fish production having plant cover percentages of 20% to 50% on ether side of the bell shaped curve. Regularly adding fish foods such as fish pellets to the system can enhance the fish production in ponds with low plant coverage.

IMO the more sumerged weeds you can remove from the pond the better the LMB will find, catch and eat GSF. The opposite is true. For initial good GSF control, I think you should basically work each year to kill all the underwater vegetation. Then while you are manually removing every GSF you can, bass eating GSF plus you focus your bass angling on removing the LMB larger than 12"-13". Then after several years ,,when you see evidence of very few remaining GSF and those survivors are basically large individuals (7"-9") then you can allow submerged plants to naturally return or beneficial ones be planted to improve the size classes of panfish. When GSF have been significantly reduced to large individuals, then you can supplimentally stock large individuals of other species of panfish, YP, PSF, Crappie (hybrids), CC.

If you want this problematic fishery to be a quick fix get the entire shallow 3/4 ac pond chemically renovated. It depends on how fast you want this fishery to be revamped and restarted. Renovation costs money but your time and efforts spent for several years getting the fishery turned around also has $$$$ value unless you want to do all this effort as a hobby and your time and efforts have low value. Doing all this for the best outcome could take up to 4 to 5 years.

IMO the long term goal as capital appropriation is to get the pond drained and and properly rebuilt with good deep basin structure to endure northern winters without needed aeartion. Michigan State univ Extension pond managemetn booklet describes best pond basin structure for northern ponds.
https://archive.lib.msu.edu/DMC/extension_publications/e1554/e1554-1989-print2.pdf


Wiley, et.al 1984. The relationship between aquatic macrophytes and sport fish production in Ilinois ponds: a simple model. North Amer. J. Fish Management 4:111-119.

I just want to comment on bait to catch your gsf, crickets. Thank me later

PondDragon, do you hand feed pellets or mealworms? If not, feeding could accustom the sunfish to your presence. Mine anticipate my throwing food every time they see me. As a result they are very quick to bite anything I drop into the water until I've pulled in several. After that I have to tantalize them with a different bait, different presentation such as movement or no movement, a small handful of their favorite food, nearly any other changeup.

Try the renegade pattern of dry fly fished wet. The double hackle seems to attract them. Chartreuse crappie nibbles will get their attention. These don't stay on the hook well so rebaiting after nearly every catch is needed. The couple of colors of GULP maggots that work best for me are natural and chartreuse. Power Bait Honey Worms are hot in my pond right now.
The various curly tail grubs and small Power Bait crayfish imitations surprisingly are ignored.

If Optimal BG pellets are floating on the pond's surface when I release a GSF, and I can visually track it after I let it go, I'll often see it head over and immediately start pulling Optimals from the pond surface. GSF are incredibly bold, aggressive feeder when they're hungry.

I do not formally feed anything in the pond, but if i see any grasshoppers or crickets on the way down I will throw them in. Yesterday, surprisingly, I threw in 3 grasshoppers while we were working on a new dock and they did not get eaten after 15 minutes. So either all the fish were spooked by our presence or it was just a bad weather day, either way the crickets/grasshoppers usually bring them running but not always. I might go buy a bag of dried mealworms and just work of habituating them instead of fishing for a while.

Bill, I absolutely agree with your ideas but there is a small issue. The pond itself is semi-natural and does not have a way to drain it, I really want to increase the depth but doing so by digging seems unlikely. My solution to both this and the vegetation issue was the pond circulator, in theory I am planning on it reducing weed coverage and, to some extent, increasing depth by angling the current down, kinda like power loading a boat. While this might add depth in places at the cost of reducing depth in others it is a sacrifice I am willing to make to get better deep basins. The pond was not always weed choked, this is a new phenomena that I believe is caused by the increased aeration making more nutrients available.
What is the purpose of removing large LMB in this scenario? I thought they would help with culling GSF? Either way, I have not been able to catch one in years so removing any seems heavy handed to me. I will double down on fishing for them once the circulator goes in (next week) and see if any normal bass techniques work.

I have 13,500 gph going into my pond from a 4" pipe. I can show you weeds growing 10 feet from that pipe in the current that the water coming out of the pipe makes. I doubt that the circulator will help you with the weed problem.

I do not have rooted plants, only chara, which to my knowledge is much less tolerant of flowing water

Please report back here after you have tried it! That's the only way we will learn.

Ponddragon,

You earlier said the predominant size of GSF that you catch is 4 to 6". What percentage of the GSF biomass is in these sizes? How numerous are the smaller sizes relative to those you predominantly catch?

I can tell you, with little doubt in my mind, that the bulk of the GSF biomass will be comprised of those sizes that cannot be consumed by your LMB. They survive because they have outgrown the majority of LMB (if not all of them). After all, if you had LMB thinning the 4"-6" GSF, wouldn't you see examples of LMB large enough to consume them?

Also, have you given any thought as to why your 7" LMB are so thin? If a 7" LMB is not getting enough to eat to have good condition. How could stocking 6" LMB immediately help? Wouldn't they have just as difficult a time finding enough forage to eat? That is what makes sense. Stocking 6" LMB will fail to help your situation unless you do something about your GSF population, IMHO.

I mean no disrespect to esshup. In his mind, your LMB are underrepresented. And here's the grub, he is right about that. What you need is around 75 or so LMB in small sizes preventing a high population of 4"-6" GSF from developing. This number is a very good recommendation for an initial stocking of LMB where large panfish are a goal. But then, in an initial stocking, the number of reproducing panfish is low. They produce a lot of YOY that can feed those 75 LMB and grow them. You have the opposite situation IMHO. I believe both the population and the Biomass of LMB is underrepresented. I also believe that both the population and biomass of adult GSF are overrepresented. A forage locked pond will not support a good biomass of LMB because prey is in short supply. So what has happened? Your LMB are in balance with the biomass that the forage locked pond can support.

So its more complicated than just a predator stocking. 4CP makes great point about being the predator of GSF. It may be difficult to source LMB that are large enough to consume optimally those 4"-6" GSF. Furthermore, the pond will not support very many LMB that large. Maybe 2 or three max and have acceptable balance (which still would not be ideal). So a population of LMB where the biomass is concentrated in large LMB would not work to grow larger panfish. They will reduce GSF in the 4-6" class, and by doing so, increase the number of GSF smaller than 4" (something counter to goals).

I am going to make a recommendation which is outlined below putting together the best advice you have thus far received.

1. Now is horrible time to stock additional predators. You need to prepare the pond for them. What you want at the time of remedial stocking of LMB is a thinned population of adult GSF producing large numbers of consumable YOY. We are probably looking at the June time frame next year for stocking LMB.

2. You need an adult GSF population that is similar to what would be ideal for an initial stocking with panfish goals. You need to remove all but around 300 of the GSF adult population. If you were to do that, you would have an adult population of 400 GSF per acre.

3. RIGHT NOW, is the time you need to be thinning GSF. Delaying would be contrary to the goal of restoring balance. Thinning now, will allow the remaining GSF to make winter in better condition. This will improve forage production next spring helping the remedial stocking of LMB to grow and control the number of GSF recruited.

4. Mark the first 150 GSF you catch in sizes > 4" and throw them back. Use whatever your preferred method of fishing is to do that. You can use a fin clip to mark them. Throw back marked fish when recaught.

5. After marking, from now until ice cover, remove all the unmarked GSF >4" you can until you are catching a 50/50 mix of marked and unmarked GSF. Use 4CPs method to leverage each cast for multiple GSF caught. If you are still catching more unmarked GSF than marked when the pond ices, then resume this removal of GSF next spring only stopping when there is a 50/50 balance in your catch of marked and unmarked GSF.

6. Watch for your first cohort of GSF YOY. When they reach sizes around 1", do your remedial stocking of LMB. I like 40 to 50 8-10" LMB. If you prefer, go with esshup's rec of 75 6" LMB. But if I were to do that, I would probably stock them before observing the GSF YOY.

I think there is pretty good chance you would see very good result by Fall of next year if you follow these recommendations. With numbers up, the LMB should more effectively control the number of GSF recruiting to the 4-6" sizes, this should be conducive to growing larger panfish. If control is sufficient, you next worry will be over recruitment of LMB. I have fished a lot of ponds with LMB/GSF combination, albeit much further south. All of these ponds had over representation of LMB. But your pond has the opposite condition in this moment.

You may ask why, if the most common condition is over representation of LMB, how did your particular pond develop the opposite condition. The best explanation I can proffer is that there may have been an event that drastically reduced the adult LMB population. The GSF population was not as affected. Once the imbalance was in place more GSF survived to be adults. This condition reduced the production of consumable forage production ... forage locking the pond. So a couple of possibilities. Possible overharvest of LMB, possibly poaching. OR a low DO event that affected the LMB more than the GSF.

Thanks for the input jpsdad. To add some clarity I will give the the data from all fish catches this year. I have only caught fish in July and August, not much fishing effort was put in earlier.
1 GSF <4 in
12 GSF 4-5in
10 GSF 5-6 in
4 GSF <6 in
1 LMB 7.25in
3 YP 8,8,8.5 in
Eight fish were caught in one day using minnows, this was the best day of fishing so far. Because of this, marking 150 fish seems pretty unlikely. I am also doubting that there is 1000's of adult sunfish in the pond. I could be wrong as I do not fish the entire pond but I feel like there should be more fish biting if there was more fish in the pond. I am definitely trusting the new tech I bought too much but I want to try it before I resort to herbicides, I have been trying to establish more desirable plants and nuking the pond would be two steps back but I will do it if the circulator does not work.
I would not be surprised if there was some event that reduced the bass population at some point but I am unaware when it would have occurred. Poaching is nearly impossible as the pond is in full view of the house and not in view of the road. A low DO event is possible as I believe there was a short period of time without aeration (~1 week), or it could have been animal predation (otters or blue heron). Despite this I have seen large schools of bass fry earlier in the year and now I am seeing single individual bass around 2 inches swimming in the shallows. If I am seeing this how necessary is restocking with bass? Is there a genetic diversity angle if we are concerned about a low adult population? If I can reduce the weeds I will begin fishing a bit harder to get a better picture of the fish stocks. I might also buy a fyke/seine net, leaning towards the seine for cost but I have more experience with fykes and prefer them.

Ponddragon,

Thank you for sharing more about your pond. To be sure, how many GSF you should mark and how many LMB you should have, will depend on what weight of GSF your pond can support. To be clear, I didn't know what it would be and so the rec as a starting place assumes your pond would support 300 lbs of GSF without a predator fish. With a good balance of predators and prey, such a pond would support about half that weight in GSF > 3". A good predator balance will correspond with standing weights of GSF that are significantly below what pond foods would maintain. So in such a pond, 150 lbs of GSF could be maintained all the time even while producing 150 lbs of prey that are being consumed by the predators. What weight of predators could be supported on 150 lbs/acre of GSF consumption at your location? Around 37 lbs/acre.

But you voice concerns about having that much carry. To give you better rec on numbers that are appropriate for your pond's productivity, we need to have a better understanding of what your standing weight of GSF is. I would recommend marking what you can. You can always remove marked fish if we determine you don't have very many. So to start ... mark 40 or 50. Stop using minnows and go to earthworms and maybe try a multiple hook rig (as 4CP recommended) to improve catch numbers. Use size 10 hooks. After marking releasing 40 or 50 GSF, then let's use the mark and recapture method to estimate the total population. This entails recording catches and whether the fish was marked or not. From this, let's make an estimate of total population. Using that estimate of total population and your population structure metrics lets gain an understanding of your standing weight with your current mix of predators. With this discovery, we can make a better recommendation for GSF and LMB population numbers. Population numbers that are not only a good balance of BG and LMB but also a good balance of populations and pond productivity.

I assumed a population that fits 300 lbs of GSF biomass and your population metrics in the spreadsheet below. Conversely, we could use mark and recapture to estimate the population and combine it with your population metrics to make a better estimate of your standing weight of GSF. What we would want to do then is to goal a smaller standing weight of GSF. We can speak about that later, but for now, if your pond's standing weight is significantly below what I had earlier assumed, we need more discovery.

Thanks for doing that math for me! I will get some crawlers and spend some time in the next week trying to pull some data out of the pond. I will keep you posted with catches.

That's great, I'm looking forward to your reports.

Alright we're back and we actually caught fish this time. Turns out all you need to do is use worms. We caught 72 total fish, 3 of which were recaptures. We'll need one or two more fishing excursions to get better recap data but this was a good start.

Some concise data if you don't want to read the excel file
19 GSF and 3 additional recaptures
averaging 6.1 inches and 73 grams, max 7.25 in and 129 g and min 4.75 in and 19 g

1 LMB 6.5 in and 55 g

33 PKS
averaging 6 inches and 73.7 grams, max 7.5 in and 143 g and min 5 in and 38 g

16 YP
averaging 7.6 inches and 80 grams, max 8.75 in and 115 g and min 6.75 in and 58 g

Excellent! You've completed the "marking" phase of your mark and recapture. We will exclude the 3 recaptures from the count of 72. What you have are 69 marked fish in your population. All of the recaptures were GSF and there is definitely the potential if you were catching and releasing in the next phase to count a fish twice. You DON'T want to do that. The next survey needs to be comprised only of unique fish (none caught twice or more). Ideally your second survey would not be biased to catchability. An example would be an electrosurvey. Another example would be traps (though perhaps not as unbiased as an electro survey) In any event, even an electro survey might be biased to one species or another. Anyways, I recommend you give your fish a rest for a week or so and then try to collect another group of samples. If you can, try to collect around 70 if you can. Don't just throw them back. Either cull them, or hold them in a trap until the second survey is complete so that you are only counting unique catches. Your initial survey is biased to catchability on earthworms. That's probably a good trait to keep, so fish you have caught twice by that survey technique are probably good ones to keep from a fishability/population management perspective. Anyways, right now, I would be reluctant to cull fish I have caught twice.

On your second survey, at least measure and weigh unique catches (the unmarked fish). Decide if you will ultimately release the unmarked fish back to your population. If the decision is yes, mark it the same as you did those yesterday and put it in the holding pen for release later. For those unmarked that you will cull, chill them in ice until you can later clean them for cooking. I would keep the previously marked fish in the holding pen along with the newly marked fish you are keeping. The number caught in this second survey and the number of recaptures in this second survey (as they relate to the initial survey) will be used to estimate populations.


Your initial survey provides a lot of useful context. If it is reasonable that fishing with earthworms is not biased to the species, then we can use the proportions of species in the catch as reflective of the populations. Your initial survey suggests that PKS are your dominant species and comprise in the neighborhood of 50% of your adult prey fish population. The remaining 50% are split between GSF and YP where the GSF have only a modest numerical advantage in the survey. All of the fish in your initial survey are adult fish that are capable of reproduction. Up to now we don't have any information for potential recruits. My sense (right now) is that recruitment is low.

Of your existing prey fish species, the PKS have the best condition averaging 103 RW, where GSF follow with 86 RW, and YP with 78 RW. All of the different species have comparable average weights PKS (73.57 g), GSF (73.57 g), with YP (79.93 g) possessing the highest average weight. For PKS and YP, RW was negatively correlated with length (RW worsens at longer lengths). This is normal when food is limiting for the population. The GSF, however, have a positive correlation with length. If I had to venture a guess as to why, my guess would be that they have some advantage for consuming some of the prey in the pond. For example, perhaps longer GSF with larger gapes have an advantage with fish and crayfish prey items. The PKS having an overall species advantage for condition, perhaps this is a benefit of exploiting snails in their diet.

The good news. You do not have stunted populations of panfish (although they are admittedly growing slower than they could be growing). I base this on Swingle's definition of a harvest sized panfish. A panfish > 1/10 of pound is considered harvestable. In grams this is around 45.45 grams. >92% of your initial survey are comprised of harvest sized panfish (per Swingle). To be stable, there needs to be a good balance of predator and prey. Presently, the risks to this population structure are losses of the adult panfish population cocurring with an inadequate population of predators (both number and size). A reduced adult panfish population will result in reduced cannibalization of YOY and higher recruitment. This higher survival resulting from a lower adult panfish population needs to be balanced by the control of the right number and size of predators. To only reduce the number of adult panfish would probably result in fewer harvestable size panfish and more smaller panfish. I do think you will need to bump the number of LMB. I like 8"-10" LMB for this purpose. Probably fewer if we are able to pin a good number for your less than 8" LMB.

Did you happen to mark your LMB? Going forward, also do that and keep track of how many have been marked. Always release your LMB, at least for now. The single LMB has good RW (120). This fish is probably in its second year of life ... posssibly later. In population dynamics, LMB less than 8" are not counted. At least not in texts authored by Anderson and/or Willis. I think whether we should count them as part of your solution depends on how fast we can expect them to grow into the 8-12 class of fish. When you have good balance, there will need to be representation in this size.

Thanks for the input jpsdad, I would love to have a different sampling method but I don't really have one as effective as worms. The PKS being the best body condition is not surprising as the snail population is quite high in the pond, as seen in the decent parasite load on most fish. Nothing too concerning but I would like to see it lower. All fish were marked, including the LMB so no issues there, but I worry my scale was off as there is no way that bass is over 100% rw; photo attached below.