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.
![[Linked Image]](https://forums.pondboss.com/ubbthreads.php?ubb=download&Number=21423&filename=Consumption%20Potential.jpg)
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.
