Dissolved Oxygen

[nofearengineer]

I've been doing a bit of reading lately on water chemistry and its effect on fish. A couple of lackluster trips to lakes, where I couldn't find the fish reliably sparked my brain into action. How much effect is the level of dissolved oxygen having?

I read that largemouth bass prefer approximately 9 ppm (parts per million) of dissolved oxygen. They can survive anywhere from 3 ppm to 13 ppm, but 5-9 is optimal. (In the winter, when their metabolism is really low due to the cold, they can tolerate as low as 1 ppm, but that's a special case.) The bass, being cold-blooded, has a metabolism that depends on the water temperature. So if the water is hot, the bass will be hungry. However, if there isn't enough oxygen in the water to metabolize (digest, layman's term) food, the bass won't eat, regardless of how high its metabolism gets. They'll either waste away from starvation or have a stomach full of rotting food, unless they can find some water with more oxygen in it.

Well, since Mark (Woody) and I are going to hit Lake Monroe this weekend, I checked Indiana's DNR website for water quality information for the lake. Turns out, they post the water temperature, height, and the dissolved oxygen at various depths of the lake. For instance, this week's numbers show the dissolved oxygen dropping to 3.1 ppm at 20 ft. So I guess I will put away my super-deep-diving crankbaits, and go for a shallower approach. Hopefully, this will save me a lot of wasted time.

However, I imagine they take their oxygen readings out in the middle of the lake. I would think in cuts where small creeks flow in, the mixing of the water might push some more oxygenated water deeper. So if the topwater or shallow-water bite isn't happening in hot weather, like we're accustomed to, I think deeper ledges near secondary points might still be good fishing spots for a deepcrank, jig, C-rig, or slow-rolled spinnerbait.

I've been trying the last couple of days to find a reasonably priced oxygen sensor online with a 30' cable or so, so I could take my own readings and record them, but no luck as of yet. If anyone here knows of any such thing, please let me know.

I'd appreciate any thoughts or comments on my thoeries/ramblings.