Can anyone answer the question-How do the occasional, but very rare 3.5 to 4 lb wild caught BG come to be? Why can't we have these in our ponds, given special and controlled conditions?
John, I don't think I can answer the question precisely, but I think the answer may lie in understanding the waters from which these BG have been caught. The BOW from which the world record BG were harvested would be a great case study. I say "were" because more than one world record size BG has been caught there (one official the other unofficial). It is not known how many, but certainly this BOW has/had produced a fair number of 2 lb+ BG.
The BOW was a limestone quarry. So here are some ideas ...
1. Being a quarry, ground water may have flowed through the BOW keeping the water cool enough to inhibit BG spawning through much of the summer. When I look at a ground water temperature map, Montgomery AL has a average groundwater temp of 67F. This is below the spawning temp of BG and so if a flow of groundwater inhibited spawning this might have had three important effects. Note that LMB recruitment would not be inhibited by this temp.
a. Delaying the first spawn would decrease BG recruitment and limit the size of 0 year BG further diminishing recruitment.
b. A shorter spawning season would increase the time BG could forage without the interference of spawning.
c. A shorter spawning season might significantly reduce spawning stress and extend lifetimes helping BG attain much greater weights.
d. Just thought of this and added as edit. If ground water flowed through the BOW it would also have a warming effect throughout the Winter which could extend the growing season.
2. With little soil, the BOW is of limited fertility. Limited fertility allows for greater light penetration and clarity.
a. Greater light penetration may have benefited water quality by deepening the depth of photosynthetic activity increasing the volume of oxygenated water. Coupled with the higher oxygen carrying capacity of cooler water, the fish in the pond may not have experienced DO depletion stresses. Low fertility would reduce nighttime respiration reducing nighttime oxygen draw downs. Perhaps less DO stress helps to extend lifetime and help fish maintain a path of growth through out the growing season. For sure, the BG in the world record BOW do not experience concurrent DO and spawning stresses in the way that fish in other BOWs often do.
b. Clarity helps BG find food and LMB control BG recruitment. Both are predators and both benefit from clarity when it comes to growth.
3. This is pretty conjectural but it is worth considering. I think the BOW may have produced a significant biomass of YOY crayfish and large insects. There would be a lot of cover for crayfish in this BOW. If this cover was sufficient there may have been significant production of a small crayfish that reduced feeding effort and provided the necessary easy growth food needed to attain the remarkable BG weights the BOW produced
OK. so these are just a few ideas of what may make this BOW favorable for producing world records and perhaps this might provide some ideas that one might employ to mimic the circumstances needed to produce very large BG.
