Thanks ewest. I have read that thread and some of the others on that particular Golden Shiner disease.
However, I have never quite understood the ramifications for our pond management.
The disease appears to spread via vertical transmission (in this case, mother to offspring). However, it also does have an "age of the mother" component to the disease. For example, in your link they say, "Pleistophora infections may be reduced by removing golden shiner females from brood fish ponds after two years of age."
First off, if the disease ONLY spreads by vertical transmission, then I would think someone would develop a "pure supply" of GSH, and the regional fish suppliers that also sell GSH would rotenone their ponds and go back to a non-diseased supply. Either that is very hard, not profitable, or there is some amount of environmental horizontal transmission that also spreads the disease. (Of course, the only things I know about fish suppliers are what I have learned on Pond Boss.)
Secondly, while it is possible for suppliers to remove the females from their brood fish ponds after two years, that is certainly not possible in the main ponds of members. How to optimize Golden Shiner populations in that situation is the reason for my questions.
Let me see if I can re-phrase the questions such that I can correctly understand the answers.
Consider a forage fish species in a pond where the population collectively has 1,000,000 eggs develop to viable fry each year. To have a sustaining population of that forage fish, a significant number of the offspring must reach sexual maturity and they then reproduce.
I can see one type of pond where the journey from fry to mature adult is RESOURCE limited. I can see another type of pond where that same journey is PREDATOR limited.
In the first type of pond, if half of the female population (the older fish) has a disease that results in them not producing fry, then only 500,000 fry would develop each year. However, since the pond is resource limited, then almost the same number of fish would reach sexual maturity. Therefore, having a disease reduce the number of fry would have very little impact on creating a sustaining population of that species in the pond.
In the second type of pond, losing half of the starting number of fry would be catastrophic. If the predators can become sated, then some of that forage fish can survive to maturity. However, if the number of forage fish is reduced, then the predators lack sufficient forage and are never sated. The forage fish are ruthlessly hunted and probably extirpated in the pond.
I believe this somewhat matches what we see in the Golden Shiner posts on Pond Boss. Some owners are able to create self-sustaining populations and some cannot create that population despite significant efforts.
Questions for any of the experts that wish to expand this thread:
1.) Do you think the life cycle of GSH and the subsequent populations in our main ponds are primarily RESOURCE limited or PREDATOR limited?
2.) If resource limited, any suggestions for pond owners to help their GSH fry grow to maturity?
3.) If predator limited, any suggestions on cover/habitat etc. that would help evade predation? Another forage species that might fill the same "predator supply" niche such that it would be possible to create a synergy where both of the forage fish populations could be self-sustaining?
Finally, let's consider a situation where the GSH population is predator limited, and the only solution is to introduce more fry into the pond. Also assume a simple reproductive disease model. Assume GSH live three years. It takes one year to reach sexual maturity. Fish that spawn during Year 2 have viable eggs that mature to healthy fry. During Year 3, none of the females produce eggs.
If Theeck culls his wild-caught GSH and tries to only stock the smallest adults when caught in the spring (assume early Year 2 fish) and the largest fingerlings when caught in the fall (assume late Year 1 fish), would it be possible to create a self-sustaining population by optimizing the offspring production in that manner for the fixed number of GSH in the pond? (If the predators equally consume all of the adult GSH, then the owner is skewing the population younger and therefore producing more fry.)
If not, would his original breeding plan of using tanks and grow out pools work if he mimicked the commercial growers and regularly removed the broodstock and introduced a ton of fingerlings every fall as the predator consumption is starting to slow? That would give him maximum production in his main pond, plus maximum production from his brood pond.
Sorry for the exceedingly long post. Just trying to generate multiple paths of additional discussion!
