Pond Boss Forums STOCKING A NEW POND Types of fish to choose General questions about population dynamics

Have a goodun' Brice....

Well George or Bruce did you catch some fish? This question always follows any report of a trip to the lake.

Thank you guys!

I fished today at a pond that I've assisted in managing.

It was awesome. I caught 5 crappie, 30ish bluegill, 1 LMB, and the biggest channel catfish of my life. It was 30 inches long. Didn't weigh it or get a picture, but I've got a good picture in my mind.

When I fished with George we had excellent success. While many people were struggling on the lake, George took me to some secret hotspots and we caught several really nice stripers. They fight so hard, it's incredible. They're bulldogs with scales.

Musings here. I think of carrying capacity as x numbers of oxygen and pond resource utilizing "thangs" contained in a body of water. That x is just as finite as the air carrying capacity of a baloon. OK, that sounds simple but what is the makeup of the denizens that go from phyto to some whopper catfish? There has to be a trade off type realtionship between x number of stunted fish versus y numbers of desired size fish. There has to be a formula (I don't know it) that considers input or resource utilization and excretions. I further figure that this nebulous # is influenced by the natural or manipulated water quality or fertility that we aspire to and talk about. However, each pond has a differing "score" when it comes to natural fertility.

In my arid area, carrying capacity means the lowest water level I can expect during a drought. Thus, I have a serious carrying capacity constraint that is not universally shared. That is exactly why I caution against fertilization and magic bullets like tilapia. Those of us in arid areas (it could be you tomorrow) just don't have the options that others do. I see manipulation of carrying capacity as betting on rain.

Guys, I have no formula nor a good SIMPLE way of estimating how many fish are in a pond based on how many are observed. I have never seen a good method or technique to do the estimation based on casual visual observations. If there was a half way reliable way to easily estimate numbers then fishery biologists would probably frequently use the technique. I also don't think Dr Dave's Fishery Techniques textbook contains a simple method either. The companion book Inland Fisheries Management discusses several techniques for estimating fish populations.

Several common techniques are used in fisheries and or wildlife management for making population estimates. Precision and accuracy varies depending on several variables.
The techniques are:
1. Counts on sample plots
2. mark-recapture
3. decline in catch per unit effort
Statistics and models are then used to calculate population estimates from the collected data.

Electroshocking is one means of commonly collecting data for the counts on sample plots technique.

Think of the statement "90% of the fish are in 10% of the pond."

Chances are the 10% with all the fish is the part of the pond we observe the most - where we feed, fish, see fish on nests, etc.

I think when you see a high density of fish in this high-usage area, you unconsciously assume the rest of the pond has the same density of fish, even if you are aware of the 90-10 rule above (and the fact that you seldom catch fish there).

Theo, that is a very good point.

That is a great point, Theo. The point is even more valid given the fact that some ponds are completely devoid of fish below the thermocline. People usually think there are fish everywhere. I'd shudder to think how many countless hours fisherman expend on big lakes fishing areas without oxygen. They come home with the old line "They just ain't biting today".

So below the thermocline the oxygen is lower? I know when I dive the thermocline can be anywhere from 22' to 32' the first thermocline then maybe again at 40'-50'. Now I am going to have to go back and read my dive notes to see if I have made note of fish sightings and depth, not that through in notes though so it may not be all that informational.
So if you had a DO tester you could test for the highest oxygen content and find the most active fish?

Could a guy the fishes tourneys benifit from this? I know a couple that have all the gadgets but I dont think I have ever heard them say anything about DO's

Little or no O2 below thermocline in stratified ponds for part of the year. There is no thermocline in ponds for most of the year where temps cause fall inversion (turnover).

I don't think there is a DO problem in the oceans as there are fish at all depths down to thousands of feet. Big lakes are more like oceans wrt DOs. Fish at all depths but once in a while you here of DO problems.

Professional fishermen use O2 meters. How do you think Houston, Parker, and Dance catch a boat load of fish in 30 minutes with a norther bearing down?

Is it permisable to moderate a Moderator?

Oceans as well as large reservoirs frequently have DO problems.

Pre-Katrina Offshore Louisiana had thousands of square miles of “dead water” as a result of excess nutrients being flushed down the Mississippi River, carried in a westerly direction by prevalent offshore currents.

These alarming conditions were likely abated by the numerous Gulf of Mexico hurricanes of 2005.

You don’t need an oxygen meter to know where the DO problems exist on lake Texoma.
All you need is good depth recorder/graph to vividly show the thermocline.

The stripers “hang out” right above the thermocline about 25 - 30 ft depth this time of the year. It is not unusual to have striped bass fish kills due to low water from drought conditions, and prolonged hot weather.

The larger stripers are most vulnerable to DO problems while the smaller fish survive under these conditions.

Sound familiar?

You bet it is ok. Please point them out as it helps me learn.

George when talking about DO problems I should have limited the comment to what we were discussing i.e. from stratification/thermocline. No doubt there are dead areas from nutrient overload but they are small wrt ocean size. I could have stated it as I don't think the oceans have a thermocline with low O2 below that depth. I am making that guess because there are fish to all depths.

Wrt large lakes I have not heard of system wide DO problems but only in a few specific areas. Just because there is a temp. difference does not mean there is a DO problem. I wonder how much of the SB/HSB problems is temp. related as opposed to DO problems. I have marked cold water thermoclines in large lakes and at the same time marked fish below the coldwater interface. I would sure like to hear from others about their info on any large lakes having system wide thermocline with DO problems.

I sure don't have all or even many of the answers on this subject and would like to here from others.

Lake McConaughy in Nebraska (30,000 acres full pool) lost all of it's trout in the 1980's and early 1990's because of a significant thermocline that would form every summer. All of the deeper areas had inadequate oxygen, so the trout were forced to elevate into the thermocline so they could breathe. Unfortunately the striped bass had the same idea and spent several weeks on a trout massacre spree.

Lake McConaughy is one of many large reservoirs that have inadequate oxygen levels in the depths for periods of time each summer due to lack of phytoplankton and wind to keep the area habitable.

Another thing to keep in mind is different species have different oxygen requirements. Is it possible the fish that are down 100's of feet in the ocean don't need as much oxygen? It still puzzled me why they aren't crushed by the increased water pressure.

Availability of disolved oxygen below the thermocline is usually associated with the trophic nature of the lake. Usually the cleaner and clearer the water the deeper the presence of dissolved oxygen. Deep, clean lakes in North America (oligotrophic to slightly mesotrophic) usually have adequate dissolved oxygen at the bottom or benthic zone all year. I know very litle about the marine environment. I have focused my studies on freshwater habitats.

As usual, Bill's right on the money. Lake McConaughy only developed this condition after the fertility greatly increased. Decades of sediment inflow and chronic drought conditions made the lake much more eutrophic. The "green" water prohibited light penetration to the deeper areas and began the process of decreasing oxygen.

Did some checking and there are thermoclines in the ocean with low DO below them.

It seems in this study that man learned the same thing wrt nets and tuna that the HSB found out with the trout in Bruce's example above.

Not the first time a deduction of mine was off base.

Cecil,

We routinely catch red snapper in the Gulf in 100 feet or greater water depths. These fish very often have grossly expanded air sacks from the pressure differential when brought to the surface. If releasing one of those fish, it it common practice to just puncture the air bladder with a needle and release the fish...supposedly the fish are fine after going through that process.

Adding to ML's comments above, I've seen some SMB Guides on the Great Lakes do the same thing w/ smallies if the catch them from more that 20' of water or so.

I never really thought about DO on our western reservoirs and lakes, but it is routine in the summer months to troll for trout and related species at depths ranging from 50 to 300 feet. On Lake Tahoe, large mackinaw are caught anywhere from 150 to 300 feet, of course the lake is much deeper (I think over 1,200 feet) but i've never learned or heard of fish at those depths. On a guide trip, my wife and I caught two 30-inchers at 225 feet last November. The macks come up looking like they swallowed a basketball, the air bladder puncture is used successfully on these fish if released.

Most of our reservoirs in the Sierra are derived from snow melt and are probably considered oligotrophic type bodys of water...really clear, somewhat sterile. On a local lake here (Folsom) I've caught rainbows trolling at over 100 feet, and spotted bass up to 60 feet deep during peak of summer, below the first thermocline, and seen nearby fish on fishfinder as deep as 100 feet (perhaps other bass).