...What are your fishery species again? General population dynamics of apex predators?...
I stocked 42 HSB, 500 HBG, & 90 RES. These went in the pond spring of 2018 after a full year of FHM explosions. Dynamics??? Not sure I understand the question, but here goes...The two HSB I caught earlier the this year were ~2 pounds and ~16" long. My catch records show that every time I have caught one, they have gained in size or were similar. I've not caught a runt HSB. The HBG tend to be in the 0.4 to 0.6 pound range. I have some recruitment, but the largest ones are less than 4 inches and most are in the 2 to 3" range with wavering populations of 1/2 inchers. I think the HSB are doing their job along with low recruitment. The craws are probably a predator of the YOY/eggs also. The RES have not been seen since stocking, but snail populations are low now. I have not seen any dead fish except a few, maybe 10, within a few days of stocking...mostly RES and two HSB...leaving 40 in the pond. I put in about 300 craws during the first two years. 90% of them were between 1 and 3" long. The remainder being up to 4".
...Have you experienced general reduction in macrophytes/FA due to dense crayfish populations?
The first two years had minor FA mats (5-10% surface coverage during the wort off the summer) that were mostly removed by me and water clarity trended during those summers around 18-24". The winters provided water clarity that got to 36". This last winter, I ran a shallow diffuser in one corner and the water stayed muddy with 12" clarity that remained throughout the summer until recently when the 150 craws were removed. Best I can tell, no other factors contributed to the turbidity improvement. FA was only in the upper few inches of the water this summer. Growing on grasses that leaned over into the pond, Water Hyacinth roots, and the dock edges. No floating mats were ever witnessed. FA has been absent for a month or better. I can only conclude that the turbidity reduced FA development, the craws kept the shoreline shallows cleaned up, and my freshly renovated pond is low in muck and nutrients.
...My .25 ac pond had all vegetation and algae denuded due to crays - my BG and RES couldn't keep up with YOY and had far too many adults. Even a few SMB couldn't help the situation, had to drain, seine, and start over [4 times!].
I have Pickerel Weed, Arrowhead, Thalia Dealbata, Botswana Wonder, & Mud Plantain, growing in the absolute shallows which do not seem to be succumbing to crawdad feasts. The Arrowhead seems to become craw food once it dies back in the fall, but during the growing season, they leave it alone.
I'm not sure what you mean by..."my BG and RES couldn't keep up with YOY and had far too many adults.". Does this mean you had way too much recruitment?
Anyhow, Starting over 4 times is TRUE dedication...the goal must have been very important to you.
QA are you concerned that low DO has killed some of your HSB?
I do not believe I have lost any fish to low DO or anything for that matter. My assumption is that I still have all my stockers and I see minimal recruitment. Lately, when I feed, the HSB and HBG will eat for as long as I throw feed. The last two weeks I have been feeding for an hour a night and throw in 0.25 to 0.35 pounds of Optimal BG (and some Optimal trial feed which, so far, has been 4mm round pellets). My fish do not frenzy during feeding...they take their time and stay spread out. I have been wondering that lower DO levels may be the cause. Feeding in the morning is practically a "no show". The DO levels during this time tend to be between 4 and 5 throughout the water column (aeration mixes it all in), but at night (aeration off all day), the DO levels are more like 6 to 10 in the upper few feet.
All in all, I am very happy with my pond, but worry about increasing biomass and seemingly low DO levels. I have not culled any fish for the dinner table and would prefer not to until the HBG are in the one pound range.
