Pond Boss Forums GENERAL QUESTIONS Water chemistry 1 acre 4’ deep pond in middle GA with Alkalinity 0

CampCobb,

I am truly unsure of what your carry capacity is/was at the time of the purchase. But the average size and the population are related to carry. Given things you said, my impression is that the carry lies within a range of lower standing weights. I think probably something between 40 and 100 lbs per acre. Reasons for thinking it isn't carrying a great weight of fish is that the water is clear and the pH and alkalinity are low. Some of the best water I have ever fished for trophy BG was a clear pond on sandy soil. Carrying a large standing weight is not required to grow large fish. But having a good balance of population and carry capacity is essential for growth and top end weights. Feeding allows for additional growth ... but not in the absence of the constraint of population. For similar numbers of fish, feeding will increase the average weight of them and in so doing, the weight carried increases. Increases in fertility also increase recruitment and it is easy to imagine an increase in population that could ... if large enough ... negate the effect of feeding on growth as those new recruits grow. Population management is an ongoing effort.

Populations are driven by recruitment and mortality. Mortality occurs naturally whether we adjust populations or not. Some say that 35% per annum is an appropriate expectation of natural mortality. Whatever the case, for a stable adult population and stable adult population structure the recruitment of adults equals the mortality of adults. Generally speaking, populations of YOY and juveniles tends to be highly variable but of relatively low proportions of the total standing weight. So high numbers but low weights. By and large we ignore YOY in terms of population management. They are essentially prey fish that undergo well in excess of 95% mortality being eaten by fish that are larger than they are.

In the spreadsheet below, I work with an assumption of 90 lbs of BG carry in your pond. Natural mortality is assumed to be 35%. In a pond where the average length of LMB is 12" or less, I would consider 4.5" BG essentially "recruited" and mostly immune from predation by LMB. So below working with those assumptions of carry, mortality, and your description (though somewhat vague) of the size of BG when you purchased the property last year. The population of recruits is chosen to balance the mortality with the size range (governed by annual growth) and the assumed carry. So ...... if the size distribution of BG then was similar that in the image below ... we can say that the population is balanced with the assumed carry.



The natural mortality reduces year class abundance each year and it is this mortality that provides for the growth of surviving individuals. So you will notice that are 36.80 lbs of BG dying naturally every year. If you divide this into the 90 lbs of carry, you get 40.88% of standing weight is lost each year. Also, it turns out that the biomass weighted proportionate weight gain averages the same number. So the standing weight falls when a fish dies and this leads to growth of the remaining fish that brings the standing weight back up to the carry. This is happening throughout the year though there may also be seasonal abundance and shortages of the food chain that cause fluctuation. But here we are just looking at population effects.

Now the next spreadsheet is the same pond where recruitment to age 2 is limited by harvest. The carry is the same but what is different is how many fish are comprising the population of age 2 and older BG. This fishing mortality of age 1 BG (132 per acre year) increase the annual growth increment by 665%. There is potential under this scenario to grow BG to around 2 lb. The very interesting part of all this is that total mortality isn't all that much higher in the second scenario. The main difference is when the mortality occurs. It is concentrated in smaller fish of age 1 and so there is less competition among age 2 and older fish for the limited resources.



In your climate (accounting for temperature moderation of your ground water) BG have potential to grow around .536 lbs annually. So even with the reduced population there is potential for growth that is not being tapped. We could either be more restrictive of the population, or, we could add more food to support more growth of the same population. Below, 240 lbs of Optimal BG is fed to support additional growth. This boosts the annual weight gain and top-end weights while keeping the same number of fish. This scenario allows for attainment of 87% of the climate limitation of growth.



So these last two scenarios represent a pond managed for 8 or 9 years controlling the recruitment of age 2 BG. The problem is that you inherited the first scenario. It isn't as simple as just controlling recruitment. The BOW has overrepresentation of age 2 and older fish and so it will require a conversion from the existing population over a period of time. Existing fish can grow, but they will need to be managed. They will not reach the sizes that your new recruits will but if managed correctly they will grow while you recruit a ladder of younger recruits. I can share more if you are interested in pursuing a trophy BG pond.