Our fishing club has access to a 35 acre private lake. The lake is full of 6"-12" bass - very seldom anything larger. But the lake has good numbers of large crappie. So- how does that happen if they are both working off the same forage base ?
The crappie utilize a lot of foods that the LMB do not process very well. Think small invertebrates. They make good use of them and so benefit more than the LMB and achieve larger ultimate weights. I have seen this also happen in an LMB-BG where the LMB population is at capacity and dominated by LMB in the size range you mention. The BG in these ponds are large with no management but the LMB are not in great condition.
Will a 12" LMB eat a 4" BG ?
Very rarely. This size would have high survival in a pond/lake where LMB were predominately less than 12". (Assuming you stock them properly acclimated when introduced). So should you stock them?
I think that depends. The lake has found a niche and grows great Crappie and panfish-like LMB. There are some who might really enjoy the Crappie and don't mind harvesting the LMB as though they are panfish. I for one wouldn't mind it particularly because the lake seems geared to do that on its own with little or no management. IOWs, the environment seems conducive to producing memorable Crappie and abundant small LMB.
To do anything that attempts to change this dynamic will be felt by all the lake's fish species. So if you are thinking about stocking BG as a food source for LMB ... I want to give you some things to consider.
BG are not great forage for Crappie and they will compete with them for invertebrate prey. So this will adversely impact what is now an excellent Crappie fishery. If you don't mind that, then you might consider stocking BG.
For the LMB that are distributed in the size class you mentioned ... BG will be competitive with them as well. The LMB are having to subsist on a diet where invertebrates play an important role for their maintenance.
So without intensive harvest, the LMB condition will probably decline rather than improve. The lake seems geared to produce abundant LMB and so this would be a headwind you would need to overcome. One way to overcome this is relentless harvest of LMB and this actually may not be feasible ... it would depend on owner/members determination to that effort. If determined, then I would suggest that the approach would be to select 2 LMB/ACRE-YEAR for survival and kill every thing else that can be caught indiscriminately. To select, crop a fin. Were I doing it, I would crop so that I could tell the year the fish was selected. You could use a location on a fin to represent the year it was selected, for example, you could use the frontal portion of the rear dorsal fin to represent 2023. You want to select fish caught on artificial lures and that are female. When one is caught, it should be released to grow ... everything else should be killed when caught to reduce LMB intra-species competition for BG forage. Other variations of this theme could be select 8 LMB/Acre in the first year and the 2 LMB/Acre in the following years. There are many LMB to harvest, at an average weight of ~ 1/4 lb a 35 acre lake with an LMB standing weight of 80 lbs/acre contains 11,200 LMB. If RW is less than 100, then maybe there is a 2 to 4 thousand more.
Worse case if you introduce BG without sufficient harvest of LMB? Because there are already abundant LMB, the introduction of BG will like result in growing large BG whose competitive pressure will overlap with Crappie and affect Crappie growth and ultimate size. The BG will record good growth. The lake will not support the number of LMB presently in the lake and with BG it will support a lower number of them (BG will not increase carrying capacity for LMB but will allow a much smaller number to achieve a larger ultimate size). Without sufficient harvest of LMB, the stage is set for an LMB mortality event which may take 1 to 3 years to develop. Surviving LMB should grow faster and the management of numbers likely more feasible. LMB recruitment will decrease as BG numbers increase. This development could affect the crappie if it allows higher survival and greater numbers reaching the 6" to 8" lengths. Crappie will be affected by lower LMB numbers and BG interspecies competition. I think the worse case for introducing BG will be smaller (possibly more abundant) Crappie. A recurring theme I see played out in small municipal lakes with stable pools and the LMB-BG-Crappie combination is small crappie where they struggle to grow larger than 8 or 9 inches ... BG that grow to around 8" too ... and LMB that can achieve 5 to 6 lbs and sometimes more. If this is path your BOW would take .... it would take some time to make the transition that would take place over a period of years.
Without the BG introduction you could still improve the lake by harvesting a recruitable proportion of its production potential. Although LMB ultimate size will always be limited to less than they could achieve with BG ... both LMB and crappie can be harvested resulting in larger fish that are in better condition. Perhaps a good place to start would be 20 lbs/acre-year LMB and 15 to 20 lbs/acre-year Crappie (it really depends on what standing weights the lake is able to carry ... I would try to harvest around 20 to 25% of the carrying capacity for each species... so if crappie carrying capacity is larger than LMB you could harvest a greater weight of them than LMB). Its not clear what they are so I am suggesting a number I hope falls below what would be too much harvest.
