Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations This paper is an absolute must read

I'll take this to mean that you agree with the principle described in the chart above but wouldn't be concerned until 18 to 24 months after stocking. I appreciate the agreement with regard to the production of consumable forage. I will say ... however ... that I believe that population restructuring should begin no later than the end of the first complete growing season. I will explain the basis for this and then let you chew on it and respond as appropriate. But first the ground work.

So I think, perhaps, you may base the time of reaching carry capacity as the time where it is evident that the growth of BG and LMB thereafter will slow/cease without thinning the populations. So to be sure, not that long ago, I also nursed a similar belief. But there was one question that nagged me ... a loose end so to speak. The LMB were not supported by the living forage ... but rather by forage they consumed ... which were dead ... and dead fish don't show up in the standing weight. That production is hidden from view.

Hidden from view though it is ... one may infer it from the standing weight of LMB. He can just estimate the weight of consumed forage that the LMB biomass would have to consume the prior 12 months to produce/maintain that weight. In Auburn's climate, that is around 5.6 lbs per annum per 1 lb of LMB. So let's say there are 60 lbs of LMB, well then, over the last 12 months there must have been 60*5.6 = 336 lbs of forage produced AND consumed that is not showing up in the standing weight. So if we drain a pond and find 60 lbs/acre LMB and 460 lbs of forage. The pond must have been capable of producing/maintaining the following forage potential in the absence of the LMB.

P = 460 + 60*5.6 = 796 lbs of BG in the absence of predators

Swingle tried various initial stocking rates, but when applying the above analysis ... what I found is that the Potential didn't vary much between ponds under fertilization. Almost always falling in the neighborhood of 800 lbs/acre +- 5%. The standing weights, however, were ALL OVER THE PLACE varying mostly between 300 and 500 lbs/acre (with some exceptions). So what I am trying to say is ... standing weights ... though they are related to fertility ... are not good measures of fertility in and of themselves. For example, a pond with excessive forage and potential limited to 500 lbs/acre could have as high a standing weight as very well managed pond with a potential of 800 lbs/acre. The latter would normally exhibit greater growth rates for BG brood fish and the standing weight of LMB would be MUCH, MUCH greater in the latter pond whose standing weight of BG is a smaller fraction of the pond's potential. Likewise, a 500 lb/acre potential pond could support a higher standing weight of LMB than a pond with 800 lbs/acre potential. For example, if the BG weight is maintained at 200 lbs/acre in a 500 lb/acre pond, it should have a higher standing weight of LMB than an 800 lb/acre pond that is maintained at 600 lbs/acre of BG.

Just consider the chart above. A Pond can fit in that chart ANYWHERE under the Y=0 curve. All that space is "it depends" and in fact, we've witnessed ponds right here in this forum that fit all over this chart. For example, 4CP's, Bocomo's, and the Wisconsin Lake in the reference paper above all occupied points left of center and closer to the Y=0 curve than the Y= 3 curve. 4CP and Bocomo, successfully addressed their problems primarily by reducing the number of LMB. Then there is Ponddragon, J.E. Craig, and ML10 ... Their ponds occupy points right of center. For Ponddragon and J.E. Craig (and probably ML10 also), their ponds are closer to Y=0 than Y=3. We've seen the current balance of member ponds ... all over the map ... but how we address these with remedial stockings/harvest are consistent with a single set of rules. These rules are based on the assumption that LMB are always the stronger species. But this is not always the case. For example, Pondragon, JE Craig, ML10 whose ponds are right of center. So ... there exists a dichotomy and sometimes the forage is overrepresented in sizes that are too large to consume (instead of the other way). The tactics that work when LMB are overrepresented and BG underrepresented ... they not only will not work in these cases ... they will, in fact, do harm exacerbating the imbalance.

The problem with initial stockings is they are all a single year class. The BG are stocked numerous enough that they reach a harvestable size within 1 year without overproducing YOY. IOWs, the forage brood occupy a large proportion of the biomass whilst most of the remainder of the potential is consumed by LMB. What the initial stocking is intended to do is prevent imbalance 1 year later and provide a manageable sustainable harvest of BG and LMB. We understand that the LMB are too numerous to continue on the same growth path without culling. But what we are missing is that BG brood are too numerous too grow at their potential either. Just averaging the potential of male and female BG to grow in Dixie (.375 lbs/annum), look at the standing weights an initial 2000/BG-acre stocking under 15% natural mortality below. Each line represents the biomass of the initial stocking upon completion of the growing season ... where they grow at their potential. The biomass of the initial stocking doesn't decline until the 7th year ... (if they grow at their potential).



So consider these questions:

Would those kind of standing weights of BG (year 2 and forward) exceed the potential of most ponds?

If yes, then wouldn't the growth of the individual brood fish be less than their individual potential? (such that they could never quite reach the potential?)

Given the individual potential for growth would be so restricted, don't we have WAY TOO MANY broodfish even after the first growing season?

Wouldn't it be advantageous to look forward and anticipate in such a way (harvest sufficiently) so that remaining brood grow near their potential and yet do not exceed a targeted proportion of the pond's potential at the next anniversary?

Would it even be better to incorporate a plan for succession of brood fish?