Pond Boss Forums Thread Like Summary - Optimizing the Survival and Growth Rates of Fry

I have read lots of discussions on Pond Boss concerning providing a food source for our forage fish and gamefish from the time they are fingerlings through adulthood.

However, I don't recall many threads on optimizing the food sources in the pond when the desirable fish are in the "fry stage". It seems to me that improving the growth rate of the fry would also increase their survival rate as they become faster to escape predation, better at hiding in cover, etc.

Further, when most of the fish are in the same size class (for example the original LMB stockers), they can create a gap in their forage base by all targeting the same food source at the exact same preferred size.

Would that be even more problematic for fry? They all hatch at close to the same time (except for BG and other multi-spawners). A good pond could literally have a million fry at the same time all competing for the same food source.

Many of the fry grow on zooplankton after their yolk sac is depleted. Does anyone manage their pond to maximize food sources for desirable fry?

Of course, in a main pond, the fishery needs very high fry mortality rates or the carrying capacity of the pond would be quickly overwhelmed after the fingerlings started gaining any significant mass.

I am mainly contemplating a brooder/grow-out type of micro pond. (But main pond advice would also be appreciated.) For example, if you were doing some brooder pairs of BG to raise additional forage for a main pond, it seems to me that the fry would quickly consume all of the zooplankton in that micro pond. Perhaps a high mortality rate is preferred, or else you would subsequently have more fingerlings in the grow-out pond than it could support?

Does anybody know how the fish suppliers optimize moving fish from the fry stage to the fingerling stage for fish that do not take supplemental feed?


A second scenario I am imagining, is a main pond with a low recruitment rate for a preferred species. For example, several members have YP in their multi-species ponds that have low recruitment rates. Would the step of optimizing the food source for YP fry pay big dividends?

Any discussion would be appreciated on my rather vague questions. Further, I frequently type up my "assumptions" on a question, because faulty assumptions are even worse than no knowledge on a topic. Please feel free to correct or clarify any of my assumptions.

FishingRod,

Probably the best way to look at this problem is to ask questions surrounding the needs at various stages of development.

To start, fish are hatched with everything they need for the immediate needs of development. Interesting, but many are hatched without a mouth opening yet. They feed on their yolks as this this development takes place. As they consume their yolks, they reach a stage of development where they are able to feed on natural foods and swim a little. This stage is called swim up. At this stage they feed increasingly on natural organisms until they are free swimming (leave the nest site and free ranging). Free swimming fry fully consume their yolks and become fully dependent on consumption of foods to survive. Different fish have different behaviors and reach this stage at different sizes with different mouth sizes. How each could be fed at this stage depends to a large extent on these variables. For example, trout invest in a large egg and large yolk and their swim up are much larger than BG or LMB. At free swimming, a trout can be feed a finely granulated prepared diet. Being much larger than BG at the same stage, they consume at lower proportions of body weight. Even so, they must be feed frequently (not twice a day). When fed manually, at least once an hour, but more commonly this feeding is performed by automatic feeders that feed intermittently ... in the early going ... more frequently than that.

Free swimming BG, another story. They have small eggs and small yolks and they are a much smaller size when they reach free swimming. They feed at much higher proportions of body weight and the frequency of their feeding is much higher. They need abundant food that is dispersed throughout the water so they can encounter food that will fit in their mouth as they swim about. Abundant food organisms that are appropriately sized is critical to the survival and growth of BG fry at this stage of development. As BG grow, their consumption slows, and they can be transitioned to a prepared diet with twice daily feedings. BG production ponds, usually have enough natural foods to supply growth needs for a few weeks. They will always become food limited, but their size at reaching food limitation will depend on the number of them still surviving. As you might imagine, this can be variable. But generally, their growth is monitored and at some point before reaching food limitation, organic fertilization is curtailed and twice daily feeding is initiated. In the beginning of this, the amount is below a maximum daily feeding rate but sufficient to fuel maximum growth. They grow rapidly until the feed rate reaches a safe limit and from that point forward, they are growing slower than could be. They are growing but are growth limited.

Combinations of organic and inorganic fertilization are commonly employed so that abundant appropriately sized natural food organisms are available to BG when they reach free swimming stage. This involves filling and fertilizing a pond so that it will be in the appropriate stage of progression to provide optimum prey sizes at free swimming. Search the SRAC pamphlets for information about this.

Tilapia fall somewhat between BG and Trout in terms of size at free swimming. Like trout, they invest in a larger egg and yolk and so reach a larger size at free swimming. But unlike trout and BG, they have a much broader range of foods they can eat. When they have to be, they are detrivores, herbivores, and even carnivores. Free swimming TP will eat detritus (wasted formulated feed fits this category), plants, as well as zooplankton and phytoplankton. They are not limited to a feeding behavior of swimming about. If they are not finding enough food to grow maximally doing that, they will resort to exploiting the bottom for foods there. This combined with lower reproduction rates means it will take longer for a crop of TP to reach limitations of growth. For the production of fingerlings, organic and/or inorganic fertilization is usually sufficient and most cost effective. For grow out of the fingerlings, formulated feeds are used to maximize production.