Pond Boss Forums Thread Like Summary - Shock survey results

I the spirit of sharing and learning, which is the core of the Pond Boss forum family, I thought I'd share the results of the shock survey we had done on April 29, 2022. I used Bjornson Pond Management again, which is one of the Pond Boss advertisers. Kevin Bjornson (the owner) works frequently with Nate Herman who is also a PB forum member and contributor. They also did a shock survey for us in Sept 2017, after which we did some corrective stocking and pond tweaks. They did a great job and are really fun to work with! For any members in Iowa, they come highly recommended.
I had the repeat survey done for two reasons. One, because I wanted to see 'what's going on down there' and get a feel for who's growing and how well, and if any of the things we've been 'doing' to our pond are having the hoped impact. Second, because we had that winter kill last spring (of 2021, which I posted about). I wondered about the impact on fish numbers and classes of the various species we have. So that sets the table.
First, a few pictures will tell most of the tale:

Nice results and pics ! Time to think about harvest of small or skinny LMB. Note the high RW of longer LMB. Harvest some in the length where RW are low or falling as there is to much competition for food in that size.

We had low LMB numbers, but saw all class sizes. We had strong BG numbers, and had heavy numbers in the 5-7" range. We had few BCP, and the ones we did see seemed stunted (big eyes). We got a couple of large GSH (golden shiners). No perch. No RES. No HSB.

We had been planning to start culling under performing LMB in the 10-12" range last summer, but then the winter kill happened. Our numbers are low enough we maybe stock a few more, to boost genetics.
We do feed, TH hanging feeder. I feed from about May thru Oct, once the water temp is over 50°. I feed a mix of Optimal BG and bass pellets (buy bag of each, hand mix), twice a day 1-2 second throws (1 to start then more once they are feeding well).

I had always hoped to catch a LMB of 5 lbs, so we're pretty excited to have shocked up that 4.88 lb bass. The boss caught a 10+" BG recently that was 1 lb even. We both loved that. She holds most of our pond records on fish size.

and here are the relative weights:

In addition HSB are more active (higher metabolism) at cooler temps so they also use up more O2 being active in winter. That plus low O2 during possible winter kill will often get the more active fish first. Also (likely not an issue here) HSB can metabolize carbohydrates from fish food that BG and LMB can't so they can become morbidly obese on fish food carbs. This makes them more apt to have O2 problems.

Water conductivity, temp and depth all effect/limit shock surveys. That is part of the art of shock survey analysis.

Kenny, I agree that the degree of precision is very important. Like you I would prefer mm and grams because these units lend to very good degree of precision for fish that are > 5" in length. mm and grams are easy to read from scales and tapes.

That said. A similar degree of precision can be obtained if one has sufficiently sensitive measuring tools. For example, if a English unit tape is divided into 1/32 of an inch AND if the one taking the measurement doesn't take shortcuts of rounding then the degree of precision is actually just a tiny bit better than mm. Even so, a tape with mm is the hammer and the 1/32" scale is a rock. I would much rather drive a nail with hammer and than a rock because it is the most appropriate tool. So same goes for the tape. Your measurement will not need conversion into decimal notation and it is far easier and faster to take the measurement very accurately with a tape graded in mm.

A weight scale needs to have sufficient sensitivity to measure small increments of change. Some scales display a greater degree of precision than they are actually sensitive to. But if grams are the degree of precision sought, the scale must be sensitive to 1 gram increments. So this is easily checked (though most instruments declare sensitivity) by adding the increment to an existing weighed item and checking to see if the increment registers. If measuring in pounds on a decimal scale the scale must provide measurement in 1 thousandths of lbs and be sensitive to register .001 lb increments.

The problem with rounding and degree of precision is very much exacerbated with fish at the smaller end of the spectrum becoming more muted with large fish.

In looking over the LMB in the table, I think the surveyors may have attained a very acceptable degree of precision. The length measurements seem to be incremented to the nearest .05". So the tape was probably 1/10 graded with possible 1/2 ticks. Whether the tenths were half ticked or not, the data collected suggests that the measurements take were taken with care either to the finest degree of precision graded on the tape or possibly making additional effort to record precision finer than the tape graduation. The nearest .05 (1/20th) inch is a little larger than a millimeter by ~ 0.27 mm. So on the first fish, assuming a very accurate measurement to the nearest .05 inch the variation or uncertainty in relative terms is less than 9 parts in 10,000. Don't know if this alarmed you but the number of exactly 13" did catch my attention. With degree of precision at 0.05 this did seem a little odd but that doesn't of course mean that they were not 13" to the nearest 0.05"

On the weight end, increments of 0.01 lbs is about 4.5 times greater than grams. Assuming the sensitivity to 0.01 lbs the uncertainty of measurement relative to a gram sensitive instrument is about 4.5 parts in 1000 for first and lightest fish. The parts uncertainty for larger fish is less than that. All in all, there was sufficient precision here I think but one surely does not want to pull out a fish de-liar and round to the nearest quarter or half inch. This would yield results that are not very accurate.

Water clarity will also affect the results. The fish that may be shocked and are deeper that can't be seen will be passed by. I've spend a number of hours on that boat!! LOL Great people.

The Gizzards are eating the base of the food pyramid for the rest of the fish in the lake. A low dose of Rotenone might be beneficial. That will kill a lot of the Gizzards but very few of the other fish.

The LMB in the survey are only able to eat the smaller Gizzard shad and not the adults. A Gizzard shad can grow from hatching to being larger than the LMB in the survey can eat in less than a year. Without something in there to help hammer the Gizzard shad, the lake will slowly decline because they are eating a lot of food that would be going to growing the small panfish.

If it was legal to stock Hybrid Striped Bass in there, that is what I'd do - on the order of 20 or so per surface acre. They will not reproduce in there, and after they are 5#-7+# then you can start allowing some to be removed. You could stock the HSB at 4"-6" fish. Bigger than a lot of the bass could eat but they'd still be able to target the small GSD in there.

There is a local lake that is 360 acres. The last net survey that the DNR did showed 60% of the fish in the lake by weight were Gizzard Shad.

If the bass are eating the fish pellets, look at buying some Stubby Steve's pellets to fish with. The bass will hit those. https://stubbysteves.mybigcommerce.com/brown-fish-food-pellet/

An adult GShad from a northern lake. If they can survive with no winter kill this is what you get.



Reduce GShad numbers by electroshock, seine, rotenone or other methods.

Attached Images