Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations This paper is an absolute must read

The paper can be found HERE.

Escanaba lake is a lake in Wisconsin where DOW controls access and regress from the lake on a permit basis. Anglers check-in and on check-out are required to declare the results of fishing which includes both released and harvested fish. Fish measurements are taken. The DOW samples the lake and incorporates various accepted methods to estimate populations, natural mortality, exploitation mortality, and standing weights. It's a very interesting read.

In the county where the lake resided, a 22 in length limit for NP was enforced starting in 1964. Prior to that, there was no length limit for NP. The study reports the metrics prior to and following the regulation change. Results:

1. There was an increase in the biomass of NP and a corresponding decrease in harvested biomass. These more or less balanced. In other words, the biomass of NP increased by about the amount fisherman were no longer harvesting.

2. Growth, Condition, and average weights of NP declined as a result of the regulation.

3. Natural Mortality increased from 15% annually to 76% annually. Fishing Mortality decreased from 46% to 6% annually.

4. Although there were 47% more NP > 22" after the regulation was enacted, they were of lower RW and average weight. Ultimate weights were also lower. Ultimate weights were lower because growth rates were slower and the average weight attained at age declined.

5. Through much of the study, panfish populations were below detectable levels and crashed as a consequence of the regulation's effect of increased density of NP. It is interesting to also note that these decimated panfish populations still produced enough juvenile offspring to support remarkable weights of predators (NP, WE, SMB, LMB, and Muskies) ... but very few panfish reached adulthood. To give you an idea of how low the populations of panfish were ... the first documented reproduction of NP occurred in 1956 when harvestable adult panfish were very low. The reason for this was not stunting. WE effectively controlled recruitment so that few panfish survived to be adults. From there, additional year classes of NP recruited. The effect of this was to diminish WE populations and this resulted in panfish catch rates increasing during the early 1960's. During this "hey day" period of the early 1960's the panfish populations provided fishing catch rates of .04 to .06 fish/hour (on average it took 20 hours to catch one panfish of harvestable size). So mature panfish were not plentiful even when they were most abundant.

Aside from what there is to learn about the need to harvest predators in their 2nd or 3rd year of life to grow fish of larger ultimate weight ... the paper is a poignant reminder that the potential for predator biomass (limited by the production of consumable prey) is inversely related to the biomass of panfish brood. We shouldn't need a paper like this to be reminded of this principle. We've known about it for a very long time. We've known that the stocking biomass/density of brooders that produces the greatest number of offspring is small. 20 pairs/acre of BG averaging .5 lbs each (~20 lbs/acre of brooders) produces the greatest number of fingerlings. The more the brooders, the fewer the fingerlings. To be sure, consumable prey biomass and production can be the lion's share of the BG biomass potential or it may only be a minor fraction of it. In the case of Escanaba Lake during the 50s and 60s, the prey consumed annually by predator fish was significantly greater than the biomass of the forage brood fish, many times greater. Although, I would not recommend managing panfish brood at such minimal levels ... it is important to understand that it really isn't possible reduce consumable forage production by removing larger than optimum forage fish by fishing. Just as important, removing larger than optimum forage fish increases the production of consumable forage.

As I try to bring my pond (3 acres & 40 y/o)back into balance, I made the assumption that the greatest number of healthy >9" male & female BG would produce the most forage fish. Big BG males defend the spawning bed & establish the best areas to spawn. Big females produce the most eggs per female. The more healthy large BG the more fry produced to grow into the most forage fish.

I have reduced the number of skinny LMB so that the fish/hour is .16. I now see more smaller BG <6" but still not the numbers I would expect in a balanced BG population. Most of the BG caught & observed are >8".

From what I have gleaned from your summary, I should now reduce the numbers of the large BG so that the smaller brooders can do their thing & quickly increase the numbers of smaller forage fish as the .5 lb fish are the most productive? While I can't get to that ideal level of 20 lbs/acre of smaller brooders a reduction of the larger >9" would be helpful?

I was not able to open your link to the paper. I am not very computer savvy.

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I had to look up Escanaba Lake & the other associated research lakes & the research they are doing at each lake. My first question was don't we already know that or can extrapolate from previous papers ? Perhaps the researchers need something to do to justify their existence? Nice to do in such a controlled situation.

JE Craig,

It opens in Edge but I notice now it won't open with Mozilla. Do a GOOGLE search on:

CHANGES IN POPULATION DENSITY, GROWTH, AND HARVEST OF NORTHERN PIKE IN ESCANABA LAKE

One of the links will reference the paper. It is served by the Wisconsin DNR. If clicking from Google doesn't work, try changing browsers.

I think we can upload pdf to pond boss. This paper is public domain (was since first published) and I don't think Wisconsin DNR would object to its dissemination if not for profit. I don't know if it's kosher per the Pond Boss Guidelines. But with approval from the powers that be ... I would upload the pdf to Pond Boss Forum.


Regarding your questions, if you recall the first discussions we had before you began removing LMB that I suggested that the problem could be an excessive population of forage adults. I was alone in that thought. But the evidence lies in the average sizes of LMB and the overwintering of YOY. I was completely alone in the suspicion. No one gave the thought any credence to that. When brood forage fish are already overrepresented, removing LMB doesn't necessarily result in good growth of individual LMB and sustainment of the LMB biomass. Particularly if the largest LMB are removed. What happens is there is less biomass consumed by smaller LMB and the forage species become more overrepresented in biomass than before. I will follow with more about balancing biomass and populations. Meanwhile, read Ponddragon's thread and how he is getting a handle of populations and biomass in his .75 acre. These metrics are essential to effective remedies. Pondragon is trying to remove 50% of his adult forage population. I'll follow up with how this is going to affect his pond going forward if he successfully achieves that fall harvest and FHM supplement goal

When you are able to download and read the paper, they will discuss a theoretical model called Equilibrium Yield. That theory predicted for Escanaba Lake ... that a 22 in Length limit would result in increased yield of NP. So the limit was expected to increase the harvest of NP per acre per year. The average however dropped from an average of 3.2 lbs/acre/year to only 0.9 lbs/acre/year. The DNR was wise to test the limit in only a few counties. These findings along with other very similar studies on length limits was altered fisheries management in the 1970s (think Richard Anderson and concepts around PSD and the control of populations through harvest in the QUALITY/STOCK lengths (2-3 years of age). DNRs have limited means to control populations to the betterment of yield other than length and bag limits. So much of what we have learned from Richardson and others about PSD is difficult to employ with bag and length limits.

Just imagine what you could do with knowledge AND experience!

A few things. I did not mean that you should have only 20 lb/acre of brooders. That would be unbalanced for BG fishing. For acceptable BG fishing and good LMB growth into preferred and larger sizes, the nonconsumable BG biomass should be no less than 50% of the total BG biomass AND the total BG biomass should be in the neighborhood of 50% of water's potential to carry BG. Best balance is in the middle of the extremes.

I don't think the size of your brooders is as important as the total biomass. If they are at least 1/2 lb average weight then they can be better relied on to spawn. They need to be in good condition.

IIRC, you have many types of fish competing for space in your community pond. Not just BG and LMB but many other fish like bowfin, tilapia, gar?, bullhead, carp?. I am trying to remember.

An example of good balance for trophy LMB is a distribution of standing weights as depicted below for 600 lb/acre potential. 62 % of the biomass is BG, ~ 1/2 of that is consumable and about 3 times the LMB biomass is consumable.

So, my burning question is this:

How do you measure that biomass in a pond (with that accuracy level) that has cover for the fish in it?

I appreciate this "burning" question esshup, as clever as you may think it to be, and I understand that you might be a little confused. I am often confused by your statements and advice as well. For example, I wondered how you could measure (with that accuracy level) the length of a 8.5" BG inside a 20" LMB just by looking at the tail extending from its throat? But in particular, I wondered how you knew to advise PondDragon to stock 75 6" LMB in his 3/4 acre? I mean, how did you measure (with any degree of accuracy) that the pond could supply the consumption biomass of forage needed to maintain/grow those 75 6" LMB? Conversely, its fair to wonder how I could know (with any degree of accuracy) that PondDragon's pond could potentially have a standing weight of 300 lbs/acre of his various forage species? The short answer is I couldn't AND you couldn't either. Although (adding 75 6" LMB - esshup) or (marking 150 GSF/panfish and harvesting until the 100 fish lookback was 50% - jpsdad) is not perfect advice, I assure you and everyone else, that my advice had the least potential to do harm and the most potential to do good.

So let's use PondDragon's (journey/example of good management) as lesson on how to get a grip on the biomass of fish in a pond.

There is truly no work around to understanding one's fish population structure and populations. This is essential knowledge and PondDragon employed the method of mark and recapture to gain a better understanding of what is in his pond, how the population is structured, and made scientific estimates of population numbers from which reasonable estimates of biomass could be made. He followed a path of discovery to understand the CURRENT BALANCE his pond was in. We were able to estimate an adult panfish population between 574 and 750 and estimate a forage brood weight of ~115 lbs. In addition, he made considerable progress on censusing his LMB population identifying two modes of sizes ~7.5" and 13" where the smaller LMB numbered 10 and the larger LMB 2. The sum of the weights is 4.2 lbs of LMB. Although it is not probably all the LMB of these larger sizes sampled, there is a good chance it is a very high proportion of them. He spent a good deal of time censusing fish and if we had knowledge of the fishing effort for the LMB, we could make an estimate of population from that as well and see how it compares with the known number and biomass of LMB.

Is this perfect? No, let me rephrase that. Is this better than knowing nothing at all? Like our combined level of knowledge when you "closed on buy 75 6" LMB" or when I said "mark 150 and remove unmarked until the 100 fish lookback is 50/50? You bet it is better to know something of the demographics than nothing at all. A lot of useful information was discovered by PondDragon. First, we discovered, there is no way on Earth his pond would support an influx of 75 6" LMB. There is just not enough of the right sized forage for them because we learned the pond is already supporting 12 fish larger than that and they are not getting enough forage to grow well. Might have been a good transaction for you, but esshup, there is no way it would have worked out well for Ponddragon. We discovered that his forage brood biomass is more than 20 times greater than this his LMB biomass. And this ... is really all we need to know ... to know that the only solution that will work is dramatically reducing the brood forage weight to increase production of YOY for LMB consumption. Before, commencing harvest of his forage brood fish, his balance looked like this:




Knowing the average weight of PKS and YP is a little over .17 lbs and that PKS can grow .15 lbs/year in his climate, he knows that he can reduce the population by 1/2 and that they have the growth potential to recover that weight over the next 12 months. Knowing that YP can grow faster than that, he knows that removing 1/2 of them will not be excessive either. So PondDragon understands that he can remove ~ 58 lbs of forage brood fish without harming the standing weight potential of his pond AND he knows the brood probably won't recover that biomass next year because there will be much more YOY production and consumption by LMB. This is something Ponddragon wants, he wants larger LMB and faster growth rates for his panfish. This action alone will not permanently fix his pond and it will be an ongoing effort. I think he understands that, but what he is doing is going to influence the next 12 months with effects that support his goal. As a result of his discovery, we learned that his pond could support somewhere in the neighborhood of 140-150 lbs of panfish in the absence of LMB. We also learned that his known population of LMB is probably sufficient to control PKS and YP. We learned, however, they are probably too small to effectively control the production of panfish YOY next year. We explored using an FHM supplement to grow his LMB over the cool months to grow the LMB to sizes that they could control larger sizes of panfish YOY next year. The FHM supplement is conditional to no more than the weight of panfish removed AND as an option ... no more than an additional 15 lbs of FHM. So knowing the pond can support at least 140 lbs of forage fish, we know the standing weights of forage fish going into winter will be below the capacity of the water to carry. So IF PondDragon is successful in meeting his harvest goal and forage supplement goal he will have transformed the estimated balance above into this:



As the surviving fish consume FHM over the winter they will grow. Particularly the LMB will grow which have significantly greater growth potential than the panfish. They will consume greater proportions of their body weight than the panfish and log proportionately better growth. If in the end the split of FHM go 50/50 to panfish and LMB and if they combined consume all the FHM by May 1st next year ... the balance on May 1st will look a little more like this:





So if he succeeds in meeting his harvest and supplement goals, he has a pond completely transformed from one with very poor balance to one of remarkably better balance next spring. His metrics next year at this time will be remarkably better than they were this year. Of course, it does depend, it depends entirely on making the adjustments and surviving the winter without winterkill. Going forward ...he will still need to be taking actions to maintain good balance and fortunately he has the tools ... and knowledge ... to continue to mold his fish populations to balance goaled growth with the pond's productivity.


So how important is the accuracy of the biomass estimates? Less important than not having the biomass estimates at all. Having discovery and making best effort estimates is BY FAR much better than "willy nilly" stocking 75 6" LMB. It's not clear to me if you are trying to declare fault with making estimates of biomass (or their accuracy) to suggest such efforts are a waste of time. If that is what you are trying to do, esshup ... it's just a strawman ... with an alterior motive. Do you have a "burning" need to convince people they can't make useful estimates of biomass and populations? How would it benefit you? I mean particularly you? If on the other hand ... you agree that effective/useful estimates of populations and biomass can be made and that they are more useful than knowing nothing at all ... I would appreciate some support on what I've been sharing about population and biomass management strategy.

Catch data alone is not enough IMO to make major stocking decisions.

But surely, you wouldn't suggest that "no data alone" is enough to? Right?

State your opinion, is PondDragon making good decisions with the strategy he is implementing? Leave me completely out of it. Give your opinion on his best course of action given all his discovery.

1. A slow growing panfish population.

2. Slow catch rates for LMB and small slow growing LMB.

3. 115 lbs estimated brood panfish standing weight numbering 574 to 750.

4. 4.2 lbs of LMB known numbering 12 LMB.

5. No YOY in the seine and trap surveys

I don't want to hear ... "he needs an electro-survey". Just don't want to hear it. It ain't going to happen ... mainly because ... it doesn't make sense for his 3/4 acre panfish pond.

Based on the knowledge acquired thus far, what should he do? When what he wants to do ... is balance his populations for growth and balance within the constraints of his pond's productivity? Can you help him do that?

If you don't think the advice I gave PondDragon will improve the balance of his pond. Then explain why. Make your case on how it is likely to do harm and not improve LMB weights and panfish weights. Explain what will happen if he performs the planned actions. If you can't, then explain how doing nothing and making no decisions and taking no actions is going to help his situation. Can you see why I object to your one sentence quip?

I believe angler catch data is a pretty good way to evaluate a fishery. Although anglers especially separate anglers have a pretty wide bias in their methods. HOWEVER, HOWEVER as with all sampling methods, there are pros and cons. Often each method can have its variability and amount of bias due to several or many reasons. There is even variability in individuals collecting samples for many subjects even in my laboratory business. Accuracy and Presision are definately different critters. It is almost always, as best as possible, to use two or three other methods to get a better idea of the results from using each method before making firm or definitive decisions. I think it is often too easy to make simple conclusions based on lack of information. It happens way too frequently in most every profession.

I question the applicable validity of the referenced Wisconsin DNR study to fisheries with other species compositions and densities of predators and different habitat conditions. I have worked with northern pike. Their behavior and productive habits are definately different than largemouth bass found in most private ponds. Thus I question how much there is comparison of the referenced WI DNR study with Joe Pondmeister's very commonly occuring bass - BG pond. One has to be careful to not apply wide scale conclusions from one study to other types of fisheries in other types of habitats. Ponds and fisheries are definitately not always the same despite even if both ponds have just BG-LMB and the main fishes. Or in ponds side by side. This is IMO why each pond fishery and even the conditions of the pond ecosystem seems to never be the same and always changing due to the constant changing conditions due to MANY VARIABLES. Some of the variables are probably still not even well understood or known. For example, DNA and genetic chemistry are still in their infancy. We as pond owners and researchers are always learning something new often monthly or daily.

Bill, this is another strawman. I didn't say that. I noted that very small populations of forage brood can produce very large quantities of consumable forage for predators. I noted that after a minimum density is exceeded that there is an inverse relationship between brood biomass and consumable forage production. I explained why. There is limited weight of forage that can be supported/produced. If the water is supporting a larger weight of brood ... then it is producing a lower weight of consumed/consumable forage. One borrows from Peter to the benefit of Paul. In the end, the sum of the two is limited to the water's productivity ... it just cannot exceed that. So one cannot harm the production of YOY by removing a reasonable amount of brood fish and in principle ... it will increase the production of YOY. Likewise, one cannot increase forage production just by adding adult forage fish in waters where the resources are being utilized to their full extent. Not to say it may work if one expands the carry (like fertilization or feeding) ... it's just that it isn't necessary to increase forage production. If one expands the carry by fertilization or feeding, the production of YOY will increase for that reason alone. A bump in the forage brood isn't required but may be desired if needed for balance in support of growth of the panfish (eg when one doesn't want excessive YOY and over recruitment of the forage species).

All this is independent of what the species are. It just doesn't matter. The principle I have laid out is true for any sustainable combination of predator and prey. This is why people should take heed and learn this principle.

If a Pond can produce no more than it can maintain. Likewise, a pond can maintain what it produces.

If a Pond can produce a potential of P pounds in a year AND if B pounds of brood forage are present after 1 year, then the production of consumable forage is limited by the difference of the potential P and the brood weight.

Therefore, consumable potential can not exceed:

C = P - B

Consumable production is the sum of the standing weight of consumable prey and production of consumed prey for the previous 12 months.

Below is chart of this maximum plotted along two curves. Y=0 is the curve where all YOY production is consumed by predators. A balance below but near Y=0 is a balance that inhibits recruitment of the forage species and favors larger populations of LMB and LMB recruitment. Y=3 is the curve where the weight of consumable prey is three times the standing weight of the LMB. This inhibits LMB recruitment and favors small populations of fast growing LMB.




It is a lookback of maximum LMB consumption potential for the prior 12 months. SOOOOO ... this does not tell one the consumption potential for the next 12 months. So 1 year after stocking, if the proportion of brood weight were 50% of potential, then the forage consumption potential for the prior 12 months could have been no more than 50% of the potential. Furthermore, if it takes 5 lbs of forage to support 1 lb of LMB for a year, we can not expect the weight of LMB to exceed 10% of the potential. If the forage potential were 700 lbs and if the brood occupies 50% of that potential then ... the LMB weight can be no higher than 70 lbs. But the LMB standing weight can only be 70 lbs ... IF ... ALL consumable sized fish were consumed ... AND IF ... there was no mortality of brood in last 12 months ... AND IF ... there was no loss of forage production to predators other than LMB in the last 12 months. So the graph is an absolute maximum above which the pond cannot produce consumption as a proportion of potential and the appropriate expectation for 700 lbs of forage potential is that this mortality production will take a share of that absolute maximum reducing what was consumed looking back 12 months.


Consider a new 1 acre pond stocked April 1st with 1500 BG and stocked May 31st with 100 LMB where the first year survival is 80%. Consider it managed for 700 lbs forage potential and that the surviving brood achieve a biomass of 300 lbs one year after stocking (BG averaging 1/4 lb). This pond had a maximum consumption potential of 400 lbs looking back 12 months. And so if the maximum was a achieved where all the consumable forage produced was also consumed by the 1st year anniversary of stocking ... the remaining 80 LMB could weigh no more than 80 lbs (averaging no more than 1 lbs). This is pretty much what Swingle had in mind with his 40's era recommendation of 1500 BG/acre and 100 LMB/acre for fertilized ponds. There wouldn't be much recruitment of BG (overwintered YOY) and BG would grow to harvestable average weights of 1/4 lb in a year ... while average weights for the LMB would be around a 1 lb.

But can that biomass of LMB be sustained if there is an increase in the standing weight of BG? The answer is ... it depends ... on whether the forage potential increases sufficiently to offset the increase in Brood weight (or forage is supplemented). But on average, young ponds increase in potential by accumulating organics where the increase in potential is around 33 lbs/acre-year. But isn't it a tall order to ask 1200 BG averaging .25 lbs each to only grow .0275 lbs each? They have the capacity to grow, on average by .375 lbs each, at least in Dixie they do. They'll more than double in weight if they get enough to eat. The only reasonable assumption is that they will not cooperate with .0275 lbs of growth each. They each, will take whatever they can, and since they already occupy 300 lbs of the anticipated 733 lbs of potential ... they are going to have take their growth from the remaining 433 lbs of potential. Of course, they are going to have to compete with their offspring in the coming 12 months for food. And there will be a split. All will split it begrudgingly because they would like to eat/grow more but what can they do about it? There is only so much food to go around. The brood will take some and the consumable sizes will take the rest. See where this is headed my friends? One year from now, when we lookback we are going to find that the production of consumed forage will balance with the remaining potential not taken up the standing weight of forage fish which has grown. Since the consumption of forage will have fallen, so too will have the supported biomass of LMB. It depends on the mortality of LMB, the LMB still could have grown in their second season, but the fact remains, the biomass will balance to no more than 1 lb of LMB for every 5 lbs of BG consumed for the past 12 months. So in a case where the brood grow and average of .12 lbs (average weight of .37 lbs) and undergo 15% mortality over the subsequent 12 months ... the look back of consumption will be:

Max Consumption year 2 = 733 - Brood Biomass - Brood Mortality biomass - Consumable forage biomass

If the consumable forage is completely consumed such that the consumable forage biomass is zero at the 2nd of anniversary of stocking:

Max Consumption year 2 = 733 - 377.4 - 45 - 0 = 310 lbs of consumed forage

This consumption would have only supported 62 lbs of LMB. The LMB Biomass is lower because the consumption in support of it is lower.

The problem? A pond is a limited resource for the fish in it ... and the brood can grow into the potential that last year produced consumption. Just a gentle reminder, my friends, that it would be good to look ahead and manage against the trend of brood occupying increasing proportions of potential year after year. You'll see better growth of your brood fish, higher biomass of LMB supported, and you'll get to eat some tasty fish.

Planning a look forward isn't as straight forward as looking into the past with hindsight. But this idea of shaping the next annual lookback to have a supported a goaled biomass of LMB and brood, I think this is something we should all be eager to learn more about.

Simply - a newly stocked pond reaches carrying capacity in 18-24 mths depending on water quality and location. From that point on (assuming no extraordinary event [feeding/fertilization] ) you are managing the relationship of and between the fish populations.

I'll take this to mean that you agree with the principle described in the chart above but wouldn't be concerned until 18 to 24 months after stocking. I appreciate the agreement with regard to the production of consumable forage. I will say ... however ... that I believe that population restructuring should begin no later than the end of the first complete growing season. I will explain the basis for this and then let you chew on it and respond as appropriate. But first the ground work.

So I think, perhaps, you may base the time of reaching carry capacity as the time where it is evident that the growth of BG and LMB thereafter will slow/cease without thinning the populations. So to be sure, not that long ago, I also nursed a similar belief. But there was one question that nagged me ... a loose end so to speak. The LMB were not supported by the living forage ... but rather by forage they consumed ... which were dead ... and dead fish don't show up in the standing weight. That production is hidden from view.

Hidden from view though it is ... one may infer it from the standing weight of LMB. He can just estimate the weight of consumed forage that the LMB biomass would have to consume the prior 12 months to produce/maintain that weight. In Auburn's climate, that is around 5.6 lbs per annum per 1 lb of LMB. So let's say there are 60 lbs of LMB, well then, over the last 12 months there must have been 60*5.6 = 336 lbs of forage produced AND consumed that is not showing up in the standing weight. So if we drain a pond and find 60 lbs/acre LMB and 460 lbs of forage. The pond must have been capable of producing/maintaining the following forage potential in the absence of the LMB.

P = 460 + 60*5.6 = 796 lbs of BG in the absence of predators

Swingle tried various initial stocking rates, but when applying the above analysis ... what I found is that the Potential didn't vary much between ponds under fertilization. Almost always falling in the neighborhood of 800 lbs/acre +- 5%. The standing weights, however, were ALL OVER THE PLACE varying mostly between 300 and 500 lbs/acre (with some exceptions). So what I am trying to say is ... standing weights ... though they are related to fertility ... are not good measures of fertility in and of themselves. For example, a pond with excessive forage and potential limited to 500 lbs/acre could have as high a standing weight as very well managed pond with a potential of 800 lbs/acre. The latter would normally exhibit greater growth rates for BG brood fish and the standing weight of LMB would be MUCH, MUCH greater in the latter pond whose standing weight of BG is a smaller fraction of the pond's potential. Likewise, a 500 lb/acre potential pond could support a higher standing weight of LMB than a pond with 800 lbs/acre potential. For example, if the BG weight is maintained at 200 lbs/acre in a 500 lb/acre pond, it should have a higher standing weight of LMB than an 800 lb/acre pond that is maintained at 600 lbs/acre of BG.

Just consider the chart above. A Pond can fit in that chart ANYWHERE under the Y=0 curve. All that space is "it depends" and in fact, we've witnessed ponds right here in this forum that fit all over this chart. For example, 4CP's, Bocomo's, and the Wisconsin Lake in the reference paper above all occupied points left of center and closer to the Y=0 curve than the Y= 3 curve. 4CP and Bocomo, successfully addressed their problems primarily by reducing the number of LMB. Then there is Ponddragon, J.E. Craig, and ML10 ... Their ponds occupy points right of center. For Ponddragon and J.E. Craig (and probably ML10 also), their ponds are closer to Y=0 than Y=3. We've seen the current balance of member ponds ... all over the map ... but how we address these with remedial stockings/harvest are consistent with a single set of rules. These rules are based on the assumption that LMB are always the stronger species. But this is not always the case. For example, Pondragon, JE Craig, ML10 whose ponds are right of center. So ... there exists a dichotomy and sometimes the forage is overrepresented in sizes that are too large to consume (instead of the other way). The tactics that work when LMB are overrepresented and BG underrepresented ... they not only will not work in these cases ... they will, in fact, do harm exacerbating the imbalance.

The problem with initial stockings is they are all a single year class. The BG are stocked numerous enough that they reach a harvestable size within 1 year without overproducing YOY. IOWs, the forage brood occupy a large proportion of the biomass whilst most of the remainder of the potential is consumed by LMB. What the initial stocking is intended to do is prevent imbalance 1 year later and provide a manageable sustainable harvest of BG and LMB. We understand that the LMB are too numerous to continue on the same growth path without culling. But what we are missing is that BG brood are too numerous too grow at their potential either. Just averaging the potential of male and female BG to grow in Dixie (.375 lbs/annum), look at the standing weights an initial 2000/BG-acre stocking under 15% natural mortality below. Each line represents the biomass of the initial stocking upon completion of the growing season ... where they grow at their potential. The biomass of the initial stocking doesn't decline until the 7th year ... (if they grow at their potential).



So consider these questions:

Would those kind of standing weights of BG (year 2 and forward) exceed the potential of most ponds?

If yes, then wouldn't the growth of the individual brood fish be less than their individual potential? (such that they could never quite reach the potential?)

Given the individual potential for growth would be so restricted, don't we have WAY TOO MANY broodfish even after the first growing season?

Wouldn't it be advantageous to look forward and anticipate in such a way (harvest sufficiently) so that remaining brood grow near their potential and yet do not exceed a targeted proportion of the pond's potential at the next anniversary?

Would it even be better to incorporate a plan for succession of brood fish?

Conjecture is just another version of wrong or right, depending.