I read the thread in the archives (and all the links) about a ponds' carrying capacity. But I must have skipped over any hard numbers that were given. With that in mind, here are my questions:

What is the dynamic carrying capacity of a 1 acre pond (expressed in pounds per ac. ft.), that is described below; and how can I determine that I am staying near (say between 80 and 90%) carrying capacity?

The pond has a surface acreage of 1 ac. Average depth is 10'. Pond is aerated, both summer and winter, and the aeration duties are shared by two Vertex Membrane diffusers, one for 50* and above water temps, one for 50* and below water temps. The pond location is USDA Zone 5. The pond is a multi-species (fish) pond.

The fish are fed AquaMax twice daily at a rate that corresponds to the "feed only what they can eat in a 15 minute time span."

Regarding sunlight: Water clarity varies from 24" when a bloom is present to over 60" during winter.

Regarding water quality and nutrient build-up. The pond is a ground water/surface water pond (terminology may vary). Approximately 40% of the water volume is below the water table level, and there is some water exchange due to the porus, sandy soil.

Now how much would that carrying capacity change if there was no supplemental feeding? (again expressed in pounds per ac. ft.)

How much would the carrying capacity change if both supplemental feeding and aeration were not present?

Am I correct in my understanding that carrying capacity means total biomass?

If that is true, then how do I figure what percentage of the total biomass should be fish?

<--- impatiently awaiting a response. 'Sperts?

Wow! Ess those are some deep questions! I have always read that on an average you can carry about 50 lbs of bass in a one acre pond. Which would not be hard to manage that part as you could tag about 20 to 25 bass or so and have some nice bass in your pond and cull the rest if they had no tag, but you can't go around tagging every dang fish in your pond to keep up with it. Your questions are good ones and I am interested in the answers you will get as my pond is 1 acre.

The answer is 3

Thank you - and goodnight.

^ Hmm, you didnt show your work?

I was considering deleting this post until I had a nibble. Making light of this question is simply to convey the following:

1. This is a great question and I want to know how it's addressed

2. It's FAR beyond my intellectual/experience reach.

Carry on!

It's not beyond my experience/educational/intellectual reach. I just don't know the answer.

montgomery now that was funny!!

High fertility ponds without supplemental feed should not have a carrying capacity over 400 pounds per acre. If you feed and aerate I wouldn't go above 500 pounds per acre. Aquaculture ponds with serious surface aeration can go much higher but it can be really tricky and is usually far above what a recreational pond person wants to deal with.

Another problem with too many fish besides the danger of algae bloom crashes etc., is the excessive weeds and filamentous algae you may be feeding. Been there done that.

Cecil provided some numbers.
As I recall carrying capacity has been discussd in previous posts several years ago. Eric or someone with search savvy?

I will provide some definitions.
In terms of fish pond populations carrying capacity is usu defined as the maximum weight of a given speices of fish that a pond will support during a time period or interval - often a year. This is different than standing crop which is the actual weight of species or group of species (community) present in a pond at a given moment. Standing crop is always changing due to additions (recruitment stockings) and losses (predation, mortality and harvest). I had to go to the book to verify this info (Bennett 1970 Management of Lakes and Ponds).

There is usually an increase in standing crop with an increase in the number of species present because of a greater use of the available food resources - different species feeding or utilizing different niches. Although simple species combinations are more managable in producing a fishery where all species are thriving i.e. reproducing and growing optimally.

Carrying capacity of a pond can be increased by fertilization, feeding and or stocking different species. Aeration that increases the volume of water available for producing fish food and fish biomass can also increase carrying capacity.

Bill:

Thanks for the terminology and clarification. Since I have a somewhat diversified pond (LMB, BG, RES, CC, GSH, maybe some FHM and for now RBT) would Cecil's numbers still hold true?

Cody says Cecil's numbers may not be real accurate for multi-species but the trend he indicates is reliable. How does one determine their fish crop weight anyway? Cecil has a fairly good estimate for single species because he reguarly drains his ponds and harvests all fish. But for us, we only can just do a big wild GUESS and or dream. See my post below.

Great info here...

To work on some of the questions.
IMO Cecil's numbers are safe estimates for sport fish ponds which most here desire.

IMO A lot of this carrying capacity stuff is speculation (theory) since it is normally hard to measure.

Specific numbers in our normal ponds are variable at best due to "it all depends".

Since fishes rarely can be seen easily or observed how many are actually present, it is hard to determine total numbers or crop weight unless a draining and census occurs. Standardized sampling can provide just educated guesses/estimates.
1. Now how much would that carrying capacity change if there was no supplemental feeding? (again expressed in pounds per ac. ft.). Hard to say specificaly. "It all depends" and it depends primarily on fertility of the ecosystem. I think in general feeding pellets sensibly can easily boost capacity by 50-100 lbs per acre. Amount of food added and number of locations would also be factors. Fish will generally only travel a certain distance to the feeding area. Maybe 50-100ft? Others my have experience with this. Thus more feeding stations will increase carrying capacity.

For natural unfertilized ponds c.capacity could be as low as 80-100bs/ac or as high as 300-350lbs/ac. Type of species present would also be factors. Different species can utilize different niches and their numbers will add to the total capacity or fish weight. Natural carp/trash fish populations have been measured at 1000 or more pounds per acre.

2. How much would the carrying capacity change if both supplemental feeding and aeration were not present? Since carrying capacity has a fair amount of theory involved in it, exact numbers are hard to provide. How does one readily measure it? Estimates can give ball park ideas. IMO feeding will boost carrying capacity more than aeration. How much more??? Maybe 20%-35%? My guess is aeration alone will usually only boost carrying capacity by a maximum of 10%, usually 5%? or less. In some cases aeration will cause little increase in carrying capacity. Those cases are for ponds that do not stratify and those where there is only a small percentge of the benthic zone that is anoxic (without oxygen in summer).

However with feeding and without aeration the increased c.capacity may not be maintained for long periods due to deteriorated water quality at certain times -summer/winter kills.

Some species of fish could develop higher carrying capacities than other fish species. Generally fish that feed lower on the food chain and/or those species that tolerate crowding and lower water quality would develop the highest carrying capacities. One can grow more carp per acre compared to LMB or BG.

I would guess that regular feeding of a high protein fish food in a low fertility pond (100-200 lbs /ac) could just about double the carrying capacity for a "normal BG-LMB pond. This number might be less (15-30%) of an increase in c.capacity for the pond that was in fertile alkaline soil/watershed and more naturally fertile because the pond already had a higher standing crop to begin with due to an enhanced food chain (productivity). This concept may be debatable.

These of course are just my opinions. Others with experience or access to information may be able to provide more info.

My view is a little different than Bill's conceptually but not factually.

Standing crop is a fixed in time measurement (what is there) while carrying capacity is a theoretical limit for a given habitat (set of facts).

The facts (habitat) include all of the physical ,chemical and biological features of the environment needed to sustain life (Fisheries Techniques 2nd). There are a lot of factors all included in the energetics concept of total energy input into a habitat.

See the archive http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92440#Post92440

I have pasted Bruce's excellent listing of some factors :

1. Water clarity/lack of suspended sediment--Lack of suspended sediment allows for better sunlight penetration into the water column, which in turn increases simple and complex plant growth, which in turn enhances micro and macro-invertebrate populations, yielding more fish.

2. Fertility--Nutrients are necessary for the above mentioned phytoplankton growth to occur. Increased fertility can occur naturally or be helped along artificially when necessary by fertilization.

3. Competition--Predator carrying capacity is directly impacted by competition from other predators, even in the form of so called "prey" species early in life, i.e. bass YOY need abundant zooplankton for several weeks before they can prey on larval fish. Carrying capacity for any one species needs to account for other species in the fish community.

4. Weather/Environment--Does warm water have a greater "carrying capacity" than cool water? I'm not so sure. Fish in a cooler pond require less oxygen, and may therefore be able to push the envelope, so to speak, as far as pounds per acre. I would guess that a warmer pond may get to carrying capacity quicker, but may not ultimately support more weight of fish. I'd be interested in comments in regards to this.

5. Feeding--This may simply be a subgroup of fertility, but experience tells me that at least for short periods of time, I can support more pounds of fish per acre in a fed pond. In the long run, however, I may be more prone to crashes. Perhaps the fed pond has a higher "carrying capacity", but implies more risk.

6. Waste removal/flow through--As nutrients build up in the form of waste products, a pond's carrying capacity decreases if it is unable to rid itself of waste. Ponds with efficient bacterial communities process waste better, thereby probably have higher "carrying capacity". Ponds with high natural flow through, such as those with a large watershed/volume ratio, have better ability to support more fish per acre.

7. Aeration--Maybe a subgroup of #6, enhance a pond's ability to rid itself of waste, thereby increasing carrying capacity. Perhaps more importantly, aeration makes "usable" water more plentiful within a pond by bringing oxygen throughout the water column. Obviously a pond that only has oxygen in the top five feet, but has seven feet of anoxic water has less net carrying capacity per acre.

8. Forage diversity--If a pond has species diversity that is appropriate to the goals of that particular ecosystem, it allows for more efficient movement of biomass up the food chain. In other words, if there is plentiful invertebrate life available that is utilizable by gizzard shad, then the presence of gizzard shad allows biomass to "flow" more efficiently up to a top end predator such as largemouth. This means a higher carrying capacity for the predator, although the carrying capacity could simultaneously decrease for species that would compete directly with the gizzard shad, such as bluegill.

9. pH--Another way that carrying capcity can be increased would be to have pH levels that minimize the presence of unionized ammonia. In water, ammonia occurs in two forms, which together are called the Total Ammonia Nitrogen, or TAN. Chemically, these two forms are represented as NH4+ and NH3. NH4+ is called Ionized Ammonia because it has a positive electrical charge, and NH3 is called Unionized Ammonia since it has no charge. This is important to know, since NH3, unionized ammonia (abbreviated as UIA), is the form which is toxic to fish. Water temperature and pH will affect which form of ammonia is predominant at any given time in an aquatic system. At high pH there is more UIA because of the OH- groups readily available in basic water. The OH- groups attract the H+ ion to form water (H2O). By stripping this ion away from NH4+ it leaves the unionized, or toxic form in the water. Toxic water means fewer fish, and less carrying capacity.

10. Social interaction--The carrying capacity is lower in a pond amongst species that spend large amounts of energy fighting over cover territory, and spawning substrate. A limited expample would be an aquarium that might be able to hold three pounds of green sunfish biomass, but ultimately never reaches that carrying capacity because the GS spend most of their time attacking and killing each other. Ponds ecosystems can behave in a similar manner if a particularly agressive species, like bluegill fight over territory during late spring and summer.


In summary, all of these factors need to be considered to evaluate "carrying capacity". It might also be more useful to think of this in terms of pounds of fish per unit of water volume instead of surface area, since one surface acre could mean anywhere from one to twenty acre feet of water.

As you can see with all these factors which are variable it is next to impossible to say X pond has Y carrying capacity. I have seen natural ponds and small lakes have CC as little as 100 lbs of fish per acre and as high as 3500 lbs (estimated based on standing crop). The problem is that for any given pond the only way to find that point is to push the limits to the crash point.

That leads us to this thread : Trophic Continuum - natural to aquaculture http://www.pondboss.com/forums/ubbthread...ite_id=1#import which has a good discussion of some factors.

A very generally used number is 400 lbs of fish per acre in a fertile pond . That is a conservative number as most people and FS writers are cautious about pushing the limit. An example is in aquaculture operations there are studies where from 13,000 lbs to 22,000 lbs per acre of tilapia were commonly grown in SE Asia.

Eric & Bruce point out how complex this topic is. Eric's references are those I was trying to remember. Eric does good work providing past topic information for us. Thanks from all of us.

I think one of the main points we should get from this discussion is to not manage as much for quantity as quality. Keep the densities below high numbers and strive for managing to produce healthy fish that have a good percentage of quality or memorable size. This means put more focus on proper harvest and balance rather on just high numbers.

Bill first it takes people like you , Bob , Dave and Bruce to write and review the material. Its not hard to remember how to find it. When you put all of us together we can come up with some good info.

Scott, is your head still spinning? HAHA Lot's to take in, but it is all great info. Moral of the story, at least how I see it is, IT ALL DEPENDS!

First of all, a big THANK YOU to everyone for taking the time to set those words to print. I see stocking numbers thrown about as fish per acre, but the size of the fish is usually left out of the equasion.

I agree, quality better than quantity. I'm trying to change the BG genetics in my pond, and I think I have a slightly better chance than a snowball in he** in accomplishing that.

While I like catching large BG, I am not willing to go to the extents necessary to transform the BOW to a trophy BG pond - I like diversity as well.

I think I need to stock Tilapia during the summer to help combat algae growth without having to rely on chemicals. The pond has historically had algae problems before it was renovated, and last year I spot treated about 1/4 of the shoreline out 4' or so due to floating mats. Last year I added 135 or so Blue Tilapia, but they were 4" at time of stocking, and I don't know how many the LMB had for lunch. I only saw a total of 4 Tilapia the rest of the year. I'll be consulting with Rex on the amount to stock in 2010.

I stocked RBT this Fall, and like having that fishery available for the cool weather when the BG/LMB don't bite readily.

While having CC in the pond for a fish fry with the neighbors is nice, not being able to catch them isn't. I think the majority of CC will be slowly weaned out of the pond. The 100 CC that were stocked Spring '09 were fin clipped, so I can sorta keep track of the CC in the pond. There were 4 CC that should be over 15# now, one was caught and tagged last Spring at 28" and 14.5#. The other 3 are the same age and in August '08 they were all the same size.

My goals right now is to get the forage base built up with Bordello's and Condello BG, RES, and GSH. I know that I have some large BG in the pond (I know there are a few 10" in there), most are 7"-9" and are males. Eventually, I would like to get the forage built up to sustain a light stocking of HSB to go along with the LMB.

I think the 100' distance for fish to travel to feed is a pretty good number. I've caught RBT right around that distance from the feeder that were noticeably thinner than the RBT that were hanging around the feeder.

My pond bounces around in size from 1 3/4 ac in the Spring to 1 ac in the late Fall/Winter, and I think the average depth is right around 9' or so. I'll use the 9 ac/ft of water figure in my standing crop calculations.

The biggest problem is figuring out what the standing crop is at any given time. With the fish that die out at certain water temps, those carrying capacity numbers are easy.

Right now, January 2010, my goals are to eventually have HSB, LMB, BG, RES, GSH in the pond, with RBT and Tilapia as transient residents. The numbers of LMB, BG, and RES in the pond now are really unknown, but I think I have a good idea of the fish numbers and size. The pond is very light with regards to LMB over 12" long. I'll bet that there are less than 20 over 12" long. But, all the LMB are over 1.0 WR, probably due to the minimal structure in the pond. I am not overrun with BG because I stocked sexually mature BG, and when stocked, it was very close to a 90%/10% mix of males to females. Plus the lack of cover let the LMB have their way with the YOY BG.

This pond was roughly 1/3 ac until the renovation that was completed in mid August 2008.

So, given those facts/figures, and using the esteemed Mr. Cody's definitions, what carrying capacity should I shoot for, with the answer expressed in % of standing crop figuring on 0% CC in the standing crop in an aerated, 9 ac/ft, supplementally fed BOW in Zone 5? (HSB, LMB, BG, RES, GSH) To make it easier, shoot for 100% standing crop and I'll reduce the numbers by 20% to make room for the tilapia and RBT.

This thread is a full semester, maybe more, of college work. I've now read everything 3 times and it confirms that "It all depends".

Let one thing get out of whack and it is a sure bet that it will affect at least one other factor. When that affected factor is water quality evidenced by decreased oxygen, all other factors will be changing faster than most of us can respond.

Maximum carrying capacity, to me, is that number I reach right before the fish kill. Been there/done that, more than once.
And, it's not the numbers of fish but what I have done by over fertilization either chemically or by the fish themselves. Cody once said that fish swim/live in their own toilet and I've disregarded that a couple of times. The fish always pay for my mistakes.

WOW. Great thread. This sounds like a great Pond Boss article.

Here is one point to consider before I take a WAG later on your blue text question.

In southern ponds a normal new pond will reach carrying capicity (max natural standing crop), meaning no feeding or fertilization but as is, in 2 yrs or less (18 mths is used also). From that point on you are managing the factors noted above in an effort to get the quality/type of fish population (#s and sizes). The amount in poundage remains about the same just the makeup of the population changes. Maybe Bill can provide the amout of time needed to reach carrying capacity up north. I bet it is about the same time but have not seen that info in studies.

Why do I provide this info ? You have fish in the pond now. Even though it is bigger now those fish will fill up the carrying capacity fast.

I'm not a Dr. of Perchology, but I would say three growing seasons for a pond here to fill up with fish.

Eric:

Thanks. I realize that the standing crop will be relatively static (in pounds) if everything else in the pond never changes. We all know that will only happen under labratory conditions, never in my BOW! That's why I was asking for a % ratio of fish species of the standing crop.

I would rather think in pounds of fish species, rather than numbers of fish because pounds of fish will give a more accurate answer.

For instance, I ran across this as a stocking rcommendation for a new 1 ac pond: (no mention of acre ft. of water)


Fathead Minnows 1-3"
20 lbs.
Golden Shiners 2-5"
15 lbs.
Largemouth Bass 3-4"
200
Hybrid Striped Bass 3-4"
50
Bluegill Sunfish 2-4"
400
Hybrid Bluegill 2-4"
200
Channel Catfish 3-5"
100
White Amur (Grass Carp) 10-12"
8
Bullfrog Tadpoles 1-3"
250
Redear Sunfish 2-4"
200

If all those fish were adults, the pond would be overloaded. But, in say 3 years without any interference from the pond owner, what would that pond look like, in terms of standing crop and carrying capacity?

I'll be looking forward to your posts later on today.

Thanks!

DD1:

It's a steep learning curve for sure! I'd like to approach maximum standing crop in the pond, but never go over it. When you really think about it and put numbers on paper, we all have a significant amount of $ tied up in the pond, and a tremendous amount of time. If I were to crash everything and kill a bunch of fish, just think what it would cost in both time and $ to get it back to say 10% below the crash level? One of my friends told me about his boss who has a nice pond at home. He went on vacation and had his father watch the house while he was on vacation. His father thought that it was a waste of electricity to run the aerator in the winter, and pulled the plug. The next spring I was told that an order was placed with Jones for ovr $10K of fish.....

That is very hard to say due to all the variables. Let me explain. If all (or a high %) of those fish reached adult status and reproduced in less than 3 years you may have 0. A gigantic fish kill. You could also have a balanced population.

I can say I would not make that stocking plan. That does not mean its wrong. It just has to much risk for me as its to many fish and not balanced with forage. But that is just my opinion.


My WAG assuming a fertile pond with some supplemental feeding would be 400 lbs of fish. No FH , a few GShainers , some big BG , a few big HBG , a balanced RES population but small #s , to many large grass carp , small LMB and a few HSB plus some (to many) large CC. A common suggestion is to shoot for 4 to 1 poundage of forage to top end predators. Irrespective it would, absent a fish kill , be at carrying capacity. The question would be the quality and make up of the population. I hope this helps some. If I did not answer your question ask it again as I may not understand.

Eric:

I just threw out that stocking plan because I found it on the 'net from a supplier in Ohio. That's not what I have in the pond.

In my pond I have LMB, BG, RES, CC and GSH (along with whatever FHM are left from the Fall) and a buttload of small Bardello BG's in a cage. Currently there are 75 RBT as well.

Right now, January 2010, my goals are to eventually have HSB, LMB, BG, RES, GSH in the pond, with RBT and Tilapia as transient residents. The numbers of LMB, BG, and RES in the pond now are unknown, but I think I have a good SWAG of the fish numbers and size. The pond is very light with regards to LMB over 12" long. 10 were stocked between 2004 and 2006 that were between 14" and 16", and 4 were stocked last Spring that were around 12" long. Those last 4 were pellet trained. But, all the LMB are over 1.0 WR, probably due to the minimal structure in the pond, (juvenile recruitement as well). I am not overrun with BG because I stocked sexually mature BG, and when stocked, it was very close to a 90%/10% mix of males to females. Plus the lack of cover let the LMB have their way with the YOY BG. I think there are a couple hundred BG left, most are between 6" and 9" long. I catch very few less than 4" long. I put right around 200 GSH in the pond this summer, as adults. They were caught with hook and line and transferred from a local BOW. As for the CC, I stocked 100 6"-9" last Spring, there should be 4 that are around 15#, and around 20 that are 2 YO, going on 3. There is a handful of RES, probably < 30; again 6"-9".

The numbers of fish in the pond are pretty close because 1) I had a severe winterkill in 2004 and I restocked by transferring fish from another BOW 2) when the pond was renovated in the summer of 2008, all the fish were sequestered in a small area of the pond and were observed when they were released into the newly renovated pond. Due to the pond renovation in 2008, I highly doubt that I have any fish from that year class.

I plan on taking out the CC, and not adding more. I want to try and change the BG genetics in the pond to Condello/Bardello BG. I'd like to get to a point where I could add some HSB to the mix as well.

This pond bounces around in size, from 1 3/4 surface acres (22-23 acre foot of water) in the Spring to 1 surface acre (9 acre foot of water) in the Winter.

Keeping in mind that I am removing the CC as they are caught and won't be re-stocking them, what do you suggest that I remove/add to the pond? I have virtually no submerged weeds, so GC aren't needed, nor wanted. I think I can keep the FA under control with Blue Tilapia.

On another note, can you point me to where I can find out the number of small sunfish that are in a pound? Say sunfish that are 2"-3" long.

The fact that the pond size fluctuates through the year and with little cover is leading to your BG YOY getting hammered. They get concentrated and the bass have a field day. I see that on a larger scale when they lower the water level of local lakes to reduce submerged aquatic vegetation...

A seine survey may give you a rough idea what the population of 2"-3" sunfish is looking like...

CJ:
What time of the year should the survey be taken? I have an area of the pond that is easily seinable, and I know someone that has a seine.....

June is usually a good time of year... You can get an idea how well the spawn in the spring was as the YOY fish should be big enough to show up in the seine run. Any time during the warmer months will give you data to work with though.

First question - How long does it take for a pond to reach carrying capacity? Research agrees with ewests answer for more southern ponds: abt 2 yrs. The cooler the climate the longer it takes - usually 2.5-3 yrs in zones 6, 5, 4, etc. It has to due with length of growing season. To get even more specific/academic the species composition and the time it takes for them to become mature and reproduce can influence when a pond reaches carrying capacity. A FHM pond would probably reach capacity quicker than a pond with just predators that do not become mature until ages of 2-4 yrs based on growing zone an species.


To answer the blue question: "So, given those facts/figures, and using the esteemed Mr. Cody's definitions, what carrying capacity should I shoot for, with the answer expressed in % of standing crop figuring on 0% CC in the standing crop in an aerated, 9 ac/ft, supplementally fed BOW in Zone 5? (HSB, LMB, BG, RES, GSH) To make it easier, shoot for 100% standing crop and I'll reduce the numbers by 20% to make room for the tilapia and RBT."
I tend to agree with Eric and Cecil - around 400 lbs per acre.

Then my question is, How you gonna measure it? And determine where you're at pound wise?

Even though I often do it, estimating based on visual factors - guessing the total weight and total numbers of fish in my pond is not very accurate and is just a WAG without some methodical and standardized sampling. Those methods consist of electroshocking, nettings, trappings, anglings and possibly mark and recaptures, each with recorded data.
The WAGs or casual observations are always notably too high. And when the pond is actually drained, one invariably says "what happened to all my fish?". Our recent good example of this was Cecil's 2009 brook trout pond draining and census.

Thus, I am saying it is IMO it is basically academic and fruitless to spend time trying to estimate the amount of fish in the pond because IMO It is too difficult for the average Joe to do it without professional help. Professionals with standard methodologies can get pretty good ball park estimates of standing stocks and carrying capacities.

IMO the Best plan is to use some good common sense methods of stocking, provide some reasonable supplimental pellet feedings, and if you feed pellets - aerate. Then don't worry a lot about carrying capacity. Then the next IMPORTANT thing to do is harvest to maintain a good BALANCED fishery to achieve your REALISTIC goals based on pond size, available habitat and location. Knowing and better understanding those are important.

GOALS can be to skew the fishery toward certain size groups or aspects of balance of sport fish i.e. stocker, quality, memorable or trophy sizes or some blend of those sizes.

As I get older, I am learning and realizing that as Bob always suggests, HARVEST is a very important part of pond management especially if one incorporates supplimental feedings or fertilizations. Or when the pond is close to carrying capacity. But close to or at carrying capacity is hard to determine correct? At least as I see it. Then what is a person to do?

Realise harvest helps maintain or insures a more healthy balance where the fish are not crowded and all are adequately growing. Think about it and do it. Not crowded fish and adequately growing are very Important features of healthy balanced fish communities. Not crowded is a key item here. Learn how to determine when they are crowded and if your fish are adequately growing. Look and check for those features / characters.

Where most people get into eventual trouble is season after season, they feed - fertilize; feed - fertilize; feed - fertilize; feed - fertilize and do not harvest. Fish become crowded and then problems start to arise. Intensity of problems gradually increase as fish grow. Crowding intensifies due primarily to reproduciton, recruitment, and growth. Feeding and fertilizings stimulate reproduciton, growth, and recruitment until an environmenal stressor/s (disease, low DO or water quality) steps in and puts the pond a few steps or poundages back ward - fish kills.

As fish poundages and crowdings build up or increase, water quality increasingly declines to where fish often die or the community becomes out of balance based on the original goal. PROPER harvest is very important to maintain "healthy carrying capacities i.e. balance and room for added growth. Knowing what and how many to harvest based on the goals are important. Based on how important Bob considers harvest to be, harvest and its guidelines are probably not discussed enough here for all the species involved in the various communities involved.

I think it is much better for the fishery to be several "degrees" under capacity than at or near capacity. At least better in terms of overall fish health and less chance of a fish kill and the majority of remaining fishes being able to maintain good or optimum growth. One asks "what is a degree"? Who knows? I made up the term. Someone else may be able to help with this or similar ideas.

PS: "The esteemed Mr. Cody" is very much a matter of opinion. Believe me, I've been called much worse. Thanks for the complement.

Great information Bill... I am curious about the nuances of harvesting. Is there a past article on this in Pond Boss or is this something that may need to be covered in a future article? Hint, hint...

We talk about human harvesting which is very controlled for the most part. The occasional hook mortality or something of that nature, although not technically a harvest, does remove a fish from the pond. You can control what species of fish, what size, what condition, etc of the fish you remove.

Other living creatures also harvest fish from our ponds. Herons, ospreys, otters and other fish... Few people want herons, ospreys or otters taking fish from their ponds, particularly otters who can rally clean a pond out. But what I am curious about is the use of fish to do the work for you. I enjoy eating fish, but may not want to eat enough fish to eat all the fish that need to be removed for one's goals for their pond. Can you rely on other fish to do the work for you?

Obviously bass remove a lot of panfish from a pond, without bass in a pond, BG and other panfish will almost surely stunt and be a mess. There has been a substantial debate over using esox species as a control over bass and other species in the pond. Can these esox species replace humans who don't wish to harvest and eat bass or panfish, or are the results so unreliable for the most part that a pond owner will just have to find friends who want fish to eat to reach their goals? Or do you just toss the harvested fish into the outflow of the dam and send them on their way to the local river?

Thanks Bill. I regularly fish the pond, I'd say at least a couple times a week during warmer fishing weather, and I will have a meal of fish once a week (one person). Once a month during the warmer months a neighbor has a fish fry, and his son and a friend usually supply the CC for the meal. The last 2 times a few came from my pond. The pond will be fished heavily for CC this year.

My nephew will also come over and fish once in a while, usually once a month May - Sept., and will take home fish for a family dinner (2 adults, 2 teenage kids). I also have a numbered fish tagging kit from Greg, and have been tagging the largest individuals that have been caught. I will start fin clipping BG this year and keep a record.

I don't know if Pondmeisters have run into this problem, but I have had bad luck using regular paper and pens to keep track of fish - the paper/ink usually gets wet. I ran across waterproof paper and a pen that will write on that paper, even if wet, in a shooting supply place. It's used to keep a shooting log. While not as inexpensive as regular paper and pen, it wasn't exhorbantly priced either. The paper is in a spiral notebook form, and they have several different sizes and colors of paper.

Bill, I know Eric will reply, but I'd like your take on it as well. Could you look at post # 201676 and comment on the 2 questions at the end?

Thanks for the information. I wish that I would have remembered more from my fisheries classes, but that was a while ago.....

What is the dynamic carrying capacity of a 1 acre pond (expressed in pounds per ac. ft.), that is described below; and how can I determine that I am staying near (say between 80 and 90%) carrying capacity?

Key word being dynamic. Going to always be changing. 100% capacity your fish biomass in a very fertile pond would be 500 lbs. You cannot determine you are staying near 80 and 90 percent. At best you can try and stay in your desired range with selective harvesting. I'd go with 400.

Now how much would that carrying capacity change if there was no supplemental feeding? (again expressed in pounds per ac. ft.)

Hmmm. No food changes the entire dynamic of the pond, about 350. Your goals down to 275.

How much would the carrying capacity change if both supplemental feeding and aeration were not present?

Feeding is a large increase of biomass. Aeration is activity, fish slow but I think the change in biomass would be insignificant. Temp would be a bigger factor. I am thinking 30%.

Am I correct in my understanding that carrying capacity means total biomass?

Carrying capacity is a measurement for biomass. As in how much? We have been talking total fish carrying capacity. Could be a species of fish, frogs, even plants. You overload your plant carrying capacity, you may decrease your fish carrying capacity. No, carrying capacity does not mean total biomass.

If that is true, then how do I figure what percentage of the total biomass should be fish?

Total biomass can be measured in the term carrying capacity. So I'd say false. Looks like you ask on the pondboss forum.

I think Bill's post above is one of the all time top posts. So much there. This thread goes to the archives link .

CJ the measure to look at is total mortality which includes natural morts and fishing morts combined. It is highly variable by location , species , human predation efforts and all the biologic factors. It is another "it depends" but can be very high as a % as it would by nature have to be due to fish spawning numbers. I can find some #s but am not sure the significance of them as a measure.

That takes me to Bill's point that measuring carrying capacity is not so important to worry about much. I agree totally. I only keep it in mind as a possible warning factor in ponds that are run or to be run more like a aquaculture operation thus the thread linked early in this thread - Trophic Continuum - natural to aquaculture

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=6;t=000162;p=1 .

Like Bill I don't think it is wise to run the pond at full tilt. That is like running a motor at high rpm for to long - something is going to break.

We are describing one of the deliminas fisheries science has struggled with since it began - what to look at and how to measure the outcome. Let me suggest the methods developed by early fishery science professors like Swingle. He knew the difficulty of measuring full pond aspects of fish populations so he developed indirect methods. Bill notes them by nature. Learning to do a population analysis can be learned thanks to Swingle and others work. You don't measure carrying capacity or standing crop as its to hard. Instead you measure fish condition as an indicator of pond health. In a natural pond condition is in part a measure of food supply and absence of stress. In crowded circumstances food is usually limited and stress higher and it is reflected in fish condition. Bill noted as follows as the common sense way " Learn how to determine when they are crowded and if your fish are adequately growing. Look and check for those features / characters. " . You can get a good estimate of this by looking at the fish , use RW (Wr) measures , do they look good and by measuring the relationship between the #s( are the numbers balance) - creel surveys , seine surveys , trap results and visual inspection.. This is not perfect but is a good measure. See the links from the archives on population analysis -
http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92492#Post92492 .

I hope this helps some.

I think the question you ask about what to add or replace is dependent on goals. If you take out big CC you could replace them with HSB as that would be a measure (HSB) that is controlled (no reproduction).

Great thread and glad that the idea that harvest is a key ingredient in maintaining a healthy(read:active, good fighters, no disease, good in the pan) fish population, was mentioned.
PROPER harvest techniques should be considered. Dont just go out and catch some fish.
As in my case soon, I want to take out about #50 lmb, #30-40 hsb, and unknown amount of BG.
Go after the larger, older, wiser fish 1st. Use larger baits, monitor their Wr, if they are over normal, maybe release some as they have learned how to flourish.
After you have culled them, then switch to a smaller LMB bait and harvest some of the younger, easier to catch juveniles.
HSB should be easier to catch, so, then target them.
Lastly, the BG will always be willing participants.

Human harvest of ponds is no doubt the least discussed tool here. It is absolutely critical in maintaining balance or goal accomplishment.

Most fun, too.

I agree the most fun part is harvesting and eating something you grew either in the garden or in the pond. Somehow it brings me more satisfaction knowing it came out of my pond than if I had bought it at the store.

IMO one of the problems with angling and management that often occurs is angling frequently and for longer periods for fun while frequently utilizing catch and release in smaller ponds (probably <2-3acres). Angling with C/R in general tends to make the actual harvest experience more difficult when needed, unless the harvest method is other than angling. In other words C/R angling creates hook smart fish that are then difficult to catch & remove when needed. This is usually not as big of a problem in larger bodies of water prob >5 acres due to the number of angling man hours per ac of water. Typically as number of angling hrs/yr/ac go down catch rates go up, i.e fish are easier to catch. If one can't catch them, how do you get them out? Dynamite is no longer sold to the public in stores.

Contact Tom G?

I think you can fish more frequently for fish lower on the food chain like BG because there are more of them meaning the angling pressure per fish is more spread out. But with bass, there are far less bass in the typical pond than BG which means there is more angling pressure per fish put on them.

Scott, Since you feed, there should be no need to reduce your stocking numbers to allow for the "addition" of trout and tilapia. As you said, they are transient. The trout will all be removed by predators, you or fish and this temporary bio-mass is intentional and of no concern. The tilapia however, on paper, are a competitor, mainly of bluegill, but in the pond, that theory falls apart. By consuming a wide range of otherwise unused and wasted nutrients in the pond, then converting it into usable forage in the form of YOY for the predators to consume, tilapia will increase the carrying capacity above what your commercial foods increase the capacity.

Just remember, Consider stocking tilapia like any supplemental feeding program that increases capacity. It is not a natural forage or nutrient source. If capacity has grown, and the supplemental program is stopped suddenly, you will have starving fish to deal with. Fish will die and the carrying capacity will eventually revert to "normal".



EDIT:

Adding tilapia with no additional feeding program does not change a BOW's total bio-mass, it re-arranges it, moving normally un-consumed plants up the food chain and into the fish. By not adding tilapia in future seasons, the bio-mass returns to normal relatively quickly.

Guys the concept of carrying capacity or standing crop is measuring fish only not total biomass. If you added the plant life and other animal life the numbers would be many times the fish # and be at any point in time the total energetic input in the pond. Like Rainman above and Bruce in an earlier archive post discuss the total energetic input/output (total biomass) in a pond which stays relatively stable and only changes form. There are some things that change total biomass. More water , more sun and better chemical fertility. See the link below.

By definition anytime you add fish without taking some out you have increased the standing crop.

I highly recommend this thread. Bob said this about it - " This has to rank in the top ten best threads ever on this website. Good stuff, guys."

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=9167&fpart=1

A great big thanks to all. I have my answers, and a direction. All I did was pose a question or two, it was the answers that made this great.

Rex, If I was running close to max. standing crop, then I would be more concerned about adding Tilapia to the pond than the trout. I think there would be more of a potential oxygem problem during the heat of the summer than winter if the aeration system were to go down. I was trying to figure out what 80% of the standing crop potential was, to make sure I had room for the Tilapia in the summer, and the trout in the winter.

Scott, I'm sure there is an ultimate max somewhere. Used in a fishing pond, I doubt adding Tilapia could come close to that maximum point though. Again, in practice, and in the YOUR pond, tilapia will improve the numbers and weight of your standing crop. Not just by the nutrients consumed, but by many other factors as well. Factors such as water quality improvement, toxin reductions, increased DO, etc. These results have been seen time and time again. Unfortunately, Reports and studies still defer to what the diets consumed by tilapia are and state (factually) that tilapia are a competitor and <I believe wrongly, declare it as an invasive species. These reports sometimes state, but usually ignore that the actual use of tilapia contradicts what most of these studies say SHOULD happen. These reports choose to ignore the fact that the species that SHOULD be harmed by adding tilapia are actually improved in nearly every single situation I am aware of.

The actual use of tilapia as a supplemental food source and a pond management tool is in it's infancy, but the results being attained are nothing short of amazing in the vast, vast majority of the ponds where they have been stocked. I and many others are still trying to fine tune stocking rates, but anything over 5 pounds and up is producing positive results, if not the specific goal desired. In the 3 short years I have dealt with tilapia, I have yet to hear a single report where stocking mixed sex tilapia was detrimental to the pond that we are concerned with here on Pond Boss.

The point I was originally trying to make sure you were clear on and trying to make. Was to think of adding tilapia as you should by feeding a commercial feed supplement. If it has been done long enough and stopped suddenly, fish will starve because any given BOW was never able to be that fertile on it's own.

Wow, This is CLASSIC! Thanks Guys!

That's why it ended up in the archives.

After re-reading this thread which is very informative, I noticed that ewest on 29/01/10, 7:34pm noted "A common suggestion is to shoot for 4 to 1 poundage of forage to top end predators." I think this value or ratio of forage pounds to predator pounds is too low and depending on ones goals is outdated.

I think in a balanced fishery the ratio should be more towards a minimum of 5:1 to best of 10:1 (forage pounds to predator pounds). I think very few sport fisheries have forage to predator ratios this high which is why pellet feeding works so well. Feeding artificially helps increase the forage ratio to ultimately boost the predator numbers and or sizes which is the goal of most pond meisters. I suggest the higher forage : predator because ecologically the food chain energy transfer pyramid uses the 10:1 ratio. In nature food biomass decreases around 10 times for each energy - food level step up the food chain.

Growing a one pound bass is a good example. It is generally accepted that it takes 10 pounds of forage to grow a 1 pound predator. Thus if our pond has what appears as an excess of forage more representative of the 5:1 ratio we will see more examples of optimum growth of the predators.

As another example. Greg Grimes (Aquatic Environmental Services) when he wants to grow trophy bass, under stocks the number of predators and increases the number or amount of forage fish, thus creating a food chain forage : predator stocking ratio approaching the 10:1 value. When this is done in southern, south central US ponds, Greg has seen LMB bass grow from fingerling to 3 - 5 lbs in one year. It is amazing what surplus forage can produce. When this occurs the big trick or challenge then for the pond owner or fish manager is to maintain this high forage to predator ratio as the fishery ages. This is where many fail at maintaining this optimum balance, probably through greed to maintain too many big impressive predators per acre. IMO the proper maintenance is done primarily by proper fish harvest and habitat management and NOT by supplemental stocking

Both the 4 to 1 forage poundage ratio and the 10 to 1 stocking ratio for LMB/BG ponds is old info based on Co-op Extension data. The poundage info is based on an ongoing pond not a start up. That is maintain 4 times the poundage in forage as in predators. By definition if you keep those #s static the LMB will be well fed. The problem is keeping any aspect static as the pond is a dynamic biological model. It has been referred to a trying to balance on a knife edge between 2 unstable states being LMB crowded on one hand and BG crowded on the other. Both tend to get out of balance as conditions change.

Newer information on stocking (reported in PB mag - Cutting Edge column) from recent studies shows best results for avoiding LMB crowded status soon after stocking in southern ponds based on a 30 to 1 stocking ratio rather than the old standard 10 to 1.

Feeding and fertilization will greatly effect both of these variables. So will a naturally productive water body. Its all energetics.

ewest, I think part of the equasion also would be the amount of cover in a pond for the forage fish to hide in. Too little and I don't know if the forage fish can keep up with predation, too much and they will make the LMB work too hard.

Like you said, it's like trying to balance on a knife edge. But, I think it's even more precise than that. Think of the knife edge on a moving vehicle, with stiff crosswinds.

You can keep a pond in relative balance, but it takes constant monitoring and knowing what to look for during those monitoring sessions.

Go on vacation for a week or two and have a flock of cormorants visit, or a family of otters and it'll slip off that knife edge in a heartbeat.

My comments were meant to encourage discussion and thought.