Pond Boss
Posted By: Bruce Condello Pond carrying capacity - 07/27/06 04:27 PM
FOR THE ARCHIVES:

It has often been a topic of conversation what consitutes "carrying capacity" of a pond.

A typical comment might be as follows:

A pond can support 50 lbs of bass per acre.

While this may be a good starting point, it would be interesting to remark on all of the variables. See this link for a good discussion of the topic also.

Topic: Trophic Continuum - natural to aquaculture --

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=19169


NOTE from ewest quote - Natural carrying capacity of all fishes present can range from 40 lb per acre to up to 2000 lbs per acre. IMPORTANT - As carrying capacity increases water quality decreases proportionally. Species of fishes present also play an important role for carrying capacity. Every waterbody is different. In the south natural carrying capacity is reached about 18 months after stocking , up north about 24 months. In poor waters carrying capacity can be enhanced by removing limiting factors (fertilizer , lime , feeding etc.). In many ponds no enhancement is needed. Management is based on goals and is a personal preference. No goal or management method is always right or wrong - it just depends.



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. Water clarity is composed of suspended micro algae, zooplankton, bacteria, and dead organic & inorganic solids aka detritus. Usually non-living detritus is more abundant than the other three categories. Just because your water has low visibility does not mean lots of living Plankton is present.

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 or fish manure from feeding the fish. Just adding nutrients or fertilizer is not the answer if the pond water chemistry is not alkaline enough for the plankton to utilize the nutrients. Adding fertilizer to a clear water pond with weeds or filamentous algae usually just results in those two "weeds" blooming instead of the plankton. Learn about and know how to do it right.

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. Higher carrying capacity always involves more risk. Be cautious and observant with high limit fisheries.

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 due to the 'flushing' factor.

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 below, has seven feet of anoxic oxygen (no DO) deficient 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 and or BG 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 or shiners.

9. pH--Another way that carrying capacity 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 example 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. Pond ecosystems can behave in a similar manner if a particularly aggressive species, like bluegill fight over territory during late spring and summer.

11. Alkalinity (Cody Added) Alkalinity as dissolved carbonates stimulates or allows the phytoplankton to do their thing and thrive and move the nutrients up to zooplankton and the rest of the food chain that is actually a part of the pond's whole FOOD WEB. Alkalinity can be increased by adding lime in the proper amounts. Alkalinity for good phytoplankton growth should be at least 20 mg/L or ppm. Fertilization without proper alkalinity will not stimulate good phytoplankton and resultant good zooplankton growth.

12. Suspended Dirt - High amounts of suspended silt decreases carrying capacity because it interferes with or reduces plankton production.


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.
Posted By: Bruce Condello Re: Pond carrying capacity - 03/08/07 02:08 AM
Link to spirited discussion on definition of carrying capacity, and the influence that structure and habitat have upon carrying capacity. A top ten thread says Bob.

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

http://www.pondboss.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000223;p=1
Posted By: ewest Re: Pond carrying capacity - 08/14/09 09:39 PM
This is an update to include the principals of energetics into the concept of carrying capacity. Bruce introduced the thought with his explanation of energy use (Ray) concept of energy input equaling the dry mass of material. The concept is used in biology and is called energetics.

Energetics is the scientific study of energy flows and storages under transformation. Because energy flows at all scales, from the quantum level, to the biosphere and cosmos, energetics is therefore a very broad discipline, encompassing for example thermodynamics, chemistry, biological energetics, biochemistry and ecological energetics.


Here is the 1st principal which Bruce covered

First principle of energetics

The increase in the internal energy of a system is equal to the amount of energy added to the system by heating, minus the amount lost in the form of work done by the system on its surroundings.

Here are the 2nd - 6th

Second principle of energetics

The total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value.

Third principle of energetics

As a system approaches absolute zero of temperature all processes cease and the entropy of the system approaches a minimum value or zero for the case of a perfect crystalline substance.

Fourth principle of energetics

There seem to be two opinions on the fourth principle of energetics:
The Onsager reciprocal relations are sometimes called the fourth law of thermodynamics. As the fourth law of thermodynamics Onsager reciprocal relations would constitute the fourth principle of energetics.

In the field of ecological energetics H.T. Odum considered maximum power, the fourth principle of energetics. Odum also proposed the Maximum empower principle as a corollary of the maximum power principle, and considered it to describe the propensities of evolutionary self-organization.

Fifth principle of energetics

The energy quality factor increases hierarchically. From studies of ecological food chains, Odum proposed that energy transformations form a hierarchical series measured by Transformity increase (Odum 2000, p. 246). Flows of energy develop hierarchical webs in which inflowing energies interact and are transformed by work processes into energy forms of higher quality that feedback amplifier actions, helping to maximise the power of the system" — (Odum 1994, p. 251)

Sixth principle of energetics

Material cycles have hierarchical patterns measured by the emergy/mass ratio that determines its zone and pulse frequency in the energy hierarchy. (Odum 2000, p. 246). M.T. Brown and V. Buranakarn write, "Generally, energy per mass is a good indicator of recycle-ability, where materials with high emergy per mass are more recyclable" (2003, p. 1).



Posted By: ewest Re: Pond carrying capacity - 04/07/10 01:29 AM
Here is an added thread that ties several of the concepts together in an example. A very good read.


http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=201295#Post201295

This is in the top ten of PB threads and should answer your question.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=201295&page=1









Posted By: Bill Cody Re: Pond carrying capacity - 04/15/13 03:04 PM
Here is another discussion of how many fish or pounds of fish that can be raised in a pond without fertilization nor feeding pellets. As usual it all depends and it depends your soil's natural alkalinity (natural limestone present) and soil fertility.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=330306#Post330306

Carrying capacity topic revisited.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=428738#Post428738

In-depth thoughtful link to a discussion on Pond Carrying capacity from Jun-Jul 2019 focused on growing large bass but the concepts and dilemma apply to all ponds. It includes a link to a spreadsheet for calculating carrying capacity.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=509420#Post509420
Posted By: Bill Cody Re: Pond carrying capacity - 04/28/16 02:08 PM
Here are some more recent comments about fertilizing and supplemental feeding. To use or not to use? Natural fertility and alkalinity of your pond soil and watershed have a big influence on natural carrying capacity of the pond. Some of the pond's fertility will be bound and unavailable in the non-fish biomass including plants and organic sediment within the pond. Water clearer than 4 to 5 ft indicates lower fish biomass and low current fertility. Fertility can vary throughout the year as recycling of organic materials within the pond occurs.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=445649#Post445649
Posted By: ewest Re: Pond carrying capacity - 11/02/16 03:13 PM
A bit on how this is measured - interesting.

The Morphoedaphic Index--Use, Abuse, and
Fundamental Concepts
R. A. RYDER

Transactions of the American Fisheries Society 111 : 154-164 ,1982

Fundamental Concept of MEI

The MEI was developed originally to meet three major objectives(:1 ) to determine empirical relationships of fish yield with abiotic factors; (2) to provide fisheries managers with an easily applied technique for first approximation of annual fish yield; (3) to provide a fundamental conceptual base for the global synthesis
of production processes in aquatic systems. The fundamental concept implicit in all morphoedaphic expressions is that energy and matter
placed in an aquatic system from external sources are channeled, cascaded , dissipated, or retained in the system because of its morphology. These two inputs regulated and constrained by the basin shape produce both a yield of fishes and other biotic outputs such as production of plants and invertebrates. Fish yield in this paper is considered to be harvest, and presumed to be a substantial predictable proportion of total internal production (turnover
rates)in intensive fisheries , energy from the sun, dispersed as heat and light ,affects rates of autotrophic production and other biological processes within aquatic communities. Matter, most relevantly nutrients and oxygen, is either allochthonous or emanates from within the lake basin. The morph or shape of the basin not only
channels energy and matter in predictable patterns, but also tends to dilute or dissipate them and consequently is a sink for both nutrients
and energy (Ryder 1978). Energy and matter inputs are inexorably linked because energy is required for nutrient transportation in both the abiotic and biotic sectors of an ecosystem.
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