Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Which fish to tag?

I am taking over management of a 10 acre pond overpopulated with bass. It is 15 feet at the deepest point and barren as an empty aquarium. The previous managers have all stocked fish on an anual basis. My plan of attack for improving the LMB fishing is to #1 Stop stocing fish (there's a very healthy BG population), #2 Add habitat in the form of sunken trees, boulders, pea gravel, stumps, etc... and #3 begin to track growth rates, etc.

There are people, like myself, that fish the pond regularly yet each year there is one day when about 40 people converge on the lake, rod in hand - the annual "fishing derby". Mostly it is a dozen or so adults and lots of kids lining the dam for 2 hours. I am going to take advantage of this opportunity to begin recording fish lengths and weights for relative weight logging and analysis.

My plan is to 1) Measure all fish caught, 2) Harvest a good number of small bass and 3) Tag some fish and release (numbered tags) for growth rate analysis

My question is (finally)...
Assuming I want to harvest fish below a certain size yet I also want to tag and release some. What is the best approach to deciding which ones I harvest and which I tag and release?

My best guess would be to harvest all below a certain size - say 10" and not tag them for release. For the next slot, say between 10" and 13" - harvest some and tag some. For those > 13" tag and release all. Am I close? The average size for a bass is between 11 and 12 inches.

Don't only go by length, also go by the weight. You could have 2 different 13" LMB, one weighing one pound, and one weighing 3/4 of a pound. Keep/tag the heavier of the 2, cull the lighter one.

When you say healthy population of BG, what size are they? Average is 11"-12", but that could be one fish 5" and one fish 19"..... (average is 12.5")

What size are the LMB that people are catching now?

Hmmm....that's an interesting thought, but If I tag based on relative weight then I will only have a record of the growth rate of my healthy population and not the population as a whole. Isn't that right? I understand your logic about keeping the seemingly more robust fish - and if I were purely thinning the herd I would agree. But since I am tagging wouldn't I want a balanced representation?

The GB are palm-sized at best with a few larger and some bigger readear. They are on beds from May to October.

I should nothave said "average" size but "typical" would have been a better choice. You can catch 8" and you can catch 14", but very rarely do you get anything over 15" and almost never anything larger than 18".

Go by condition index (RW). Release the ones with the best RW and cull the worst RW. By definition you will be culling from the group that is overcrowded mostly as they will be the ones not getting enough food. If you catch a 13 or 14 and it has bad RW then take it out. This assumes that the derby is not just after the spawn.

"But since I am tagging wouldn't I want a balanced representation?"

No as growth rate will be better for those who have the competition removed not just the tagged fish. You are only going to tag a small % of the fish. Plus as the population balances all will have similar growth rates within their competitive class size. Do RW on all fish caught as it will be the measurment tool to compare to the tagged fish growth rate. Keep in mind that the goal is to have all the caught fishes’ (general population) RW equal the RW of the tagged fish (memorable = best population).

Ditto what ewest said. We were both typing the same thing.

I would keep track of all BG caught too, not just the LMB. It might be hard to weigh the smaller BG, but at least measure and count the smaller BG. You'll probably see a certain year class or size class is missing or has minimal numbers due to the LMB targeting that size BG.

A LMB has to be a certain weight (at one time) to get to a certain length. So, if a fish is underweight, it was at the correct weight previously and is now not finding enough food in the correct sizes to eat. That's why a length only measurement won't tell you much, you also have to weigh the fish. There might be enough food in smaller sized fish, but it has to expend more energy per mouthful of food, so it's not adding weight, or it could be even loosing weight.

Excellent information - thank you both - I'll be sure to track LMB & BG.

Pat

Now that you mention it.....the derby is May 26th. Too soon after the spawn? I'm in central Missouri.

What's your water temp now? LMB spawn around the full moon, which is April 6th and May 6th this year.

I don't know and I won't be able to measure until I get back out to the lake April 20th. I believe late April and early May sounds about right for the lake. How soon after the spawn do you think it would be "too soon" to gather data?

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How soon after the spawn do you think it would be "too soon" to gather data?

Thanks

Which data ? Leave them alone until the fry are on their on. Then gather data but you have to account for spawn effect on RW (up to 30 %) in some species.

Yes, I'm talking about relative weight. I don't want the data to be skewed by the spawn and I definitely don't want to attempt any manual adjustments. That sounds a lot like purposely skewing the data.

The lake should be at about 60 degrees by mid April. I have a guy checking lake temps regularly to know when to apply algae control chems. Using April 15th as an estimate - that would allow for 40 days before we hold the derby on May 25th. I'm trying to determine if that window is long enough to assume "spawn effect" won't play a mojor role in our gathering of rW that day.

I shhould add that the average length LMB is about 11" in this 10 acre pond. I'll likely be logging rW for a range mostly between 10" and 13". Would bass that small even be spawning? I see a few beds in the lake every year - and they're usually occupied by fish 13+" in length.

Thanks for the replies. The folks running the derby want to know what my plans are and I'm not sure what to tell them just yet. If nothing else the event will serve as a great way to harvest a lot of fish. I was hoping it would give me a starting point for measuring LMB health over time - but I want to be sure I get good data. As they say, "Garbage On, Garbage Out".

RW is always effected by the spawn by definition. Up or down it effects weight - no way around that. That is why in the data gathering you need dates and some pics of the fish. RW is best gather over time not all in one event.

In your location May 25 may be in the spawn window. Size and age at first spawn varies. Up north it is often age 2 but in the deep south age 1 is common. First stocked fish (in a pond with no similar fish)often spawn earlier than in previously stocked ponds (with adult fish of the same species).

I do plan to gather data continuously over the course of the next 5 years. I was thinking that if I only gathered data during the same time frame each yea, say.... mid June to mid September, that I would get a faie assessment of how the improvements made to the lake are affecting the fish. I don't want to waste time monitoring fish during a period with too many outside forces influencing the metrics I'm monitoring - such as the spawning period.

But, that being said - the opportunity to gather a lot of informtation at one time is one that shouldn't be missed. I can always filter out data by date ranges when querying my database.

There are always outside (natural) factors at work , winter , spawn , weather, fishing pressure , harvest , feeding , stress etc. The way to avoid a skewed sample is to have a big sample size over all time periods.

Hmmmm...now that makes sense. Thanks for talking me through all this. It's been very helpful.

Pat

Anytime - that is why we are here !