Back to the original question... ASSUMING they are gizzard shad how do I move forward? I spent the summer removing bass (goal of 20lbs/acre). If I have gizzard shad would that have unintended consequences? Would it give shad the opportunity to over populate and end up dominating the biomass of the pond? Or am I still on the right track going forward with a yearly goal of removing bass?
In a Northern pond, Gizzard shad WILL overpopulate no matter what you do, that is if shad management methods aren't implemented. The shad will grow too large for the bass to eat in less than two years. In a 19 ac BOW, nothing is cheap. The state here in Indiana, in larger public bodies of water will do a low dose of rotenone to kill most of the gizzard shad but not any of the other fish. If it was my pond, I'd start a feeding program for the BG to bump their population and fecundity, then I'd do a low dose rotenone treatment and follow up after that treatment in a month with a whole lake electroshock survey, even the open waters to monitor the shad population. While some shad are OK, getting too many will skew the fish biomass. Then 2 years down the road I'd do another electroshock survey to check the GSD population and LMB population. If GSD population is rebounding from when the first survey was done, I'd schedule a low dose rotenone treatment for that year and the next two consecutive years. THEN schedule another electroshock survey to monitor the fish population after those 3 treatments. I would schedule the treatments for late June to allow the treatments to target any YOY GSD that were hatched the prior 60 days vs. letting them grow larger and most likely spawn the following year.
For an example a local 365 acre lake had Gizzards introduced years ago. (the whole lake was rotenoned by the state in the late 1960's due to a carp/gar overpopulation). When the DNR did a gill net survey some years ago they found that over 60% of the fish biomass in the lake was Gizzard Shad. Maybe due to the gill net size, but the majority of the shad caught were too big to be utilized by the LMB for food.
Some other impoundments in the state that have a Gizzard Shad problem were stocked with Stripers, NOT HSB.
Oops, I forgot the LMB question. I'd continue to remove the LMB, but go according to RW. Remove the same poundage per surface acre (20#) but only LMB that were below 90%. If post spawn, I'd drop that RW figure to 80%-85% depending on how the LMB looked. i.e. a post spawn female will have shoulders but have a low RW. Once you catch enough LMB you will be able to tell if it's a cull or a return to the BOW.
