Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Evaluating New Pond and New Fish

I think both of these are great questions. I've asked these questions as well. With regard to the production of gametes and the energies expended mating and protecting young, it is very reasonable that such carry a cost of energy that was prior consumed and is therefore lost. There is likely an inefficiency introduced.

The way I see growth is that there are maximum rates of building frame. One cannot grow a 20" LMB in one year (but a 13" 2lb LMB is possible). There seems also to be a limit to the excess weight that can be put on a frame. The highest RW that I have knowledge of is ~182. I have wondered why. But I suspect that when a fish reaches such a threshold the consumption slows down to be in balance with that maximum. To be sure, different individuals have something unique to them that governs its own limits of growth. If it can eat all it needs to fulfill the energy consumption required to reach that limit, then its greatest potential will be attained. But each fish is different and there is variation where like people each has a different potential growth track and a different actual growth track.

There is daily maintenance cost that is largely a function of the weight/gross energy of the fish. So in as much as this is true, when a female builds eggs, she also increases her daily energy needs for maintenance while she carries them. IOWs she must maintain egg mass too. So after she lays them, her daily energy needs also drop. This does have the effect of increasing the efficiency of following consumption. IOWs, dropping the maintenance cost of maintaining eggs helps her gain the weight back. In fact, at the same temperature, the same consumption required to maintain her with the eggs will grow her after laying them to the same weight she was before (eventually ... with growth slowing as the limit of maintenance is reached).

Every now and then we talk about compensatory feeding where fish are denied food and then subsequently utilize food more efficiently than if not denied food. From the stand point of energetics, this can in part be explained by the loss of body mass resulting from being denied food. It lowers the maintenance need and increases the excess energy consumed that can be converted to gain. So by and large, fish can recover from periods of food shortage better than one may otherwise imagine. The cost of maintaining body mass is not inconsequential and according to the math of energy theory when applied in simulation, it takes similar amounts of energy to attain the same body mass over a fixed period of time. IOWs, consider two fish one weighing 1 lb and another weighting 1.5 lbs. Both gain to 2.5 lbs over the same conditions and length of time. So the first fish gains 1.5 lbs and the second fish gains 1 lbs. When I simulate this under constant daily rate of gain, the consumption varies by less than 3%. IOWs it takes very nearly the same amount of forage to grow either fish to 2.5 lbs.

That was definitely an eye opener for me. It's always a good time to feed LMB. Don't ever think all is lost due a loss of RW unless the cause is disease or something that cannot be overcome with forage. According to energetics, LMB will recover so long as they consume the forage needed to do so.