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Winter 2019
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reached where the density of the cooling surface water becomes greater than the density of the deep water, and overturning begins as the dense surface water moves down under the influence of gravity.
This process is aided by wind and other process (currents for example) that agitates the water. This process is referred to as the “fall turnover.” Often times there is an apparent change in water clarity and frequently an associated algae bloom associated with the replenished nutrients in the surface layers.
During this time, temperature and dissolved oxygen profiles are nearly equal throughout the water column.
Formation of a winter thermocline occurs in a similar fashion. Colder denser water will sink, surface waters will lose heat to the atmosphere and thermal input will be limited, causing the surface layer to be colder.
The thermocline during this period will actually be a band of slightly warmer water, sandwiched between layers of colder water. The differences in temperature may only be a few degrees, but when you are cold, that spot that’s just a little warmer will feel pretty good to a bass.
The gradients will not be as steep as observed during summertime and are much less pronounced. Reservoirs are dynamic and can change for example
with significant influxes of winter runoff – in which case there may be an influx of cold or warm water.
PUTTING IT ALL TOGETHER
What does this mean to us anglers? Well, it helps us analyze the conditions and either eliminate water or establish a starting point to begin to locate and pattern bass. In the peak of the summer – as the sun is high overhead, we can turn our attention to deeper water and structure where the bait and bass will be more concentrated.
Often times I’ll look for highways that allow bass to easily move up and down with the bait with sunlight (long points, flats adjacent to ledges, etc.).
Cody Meyer provided an excellent example in an article published in Westernbass this past year. (https://www.westernbass.com/article/finesse- tactics-cody-meyer-seaguar).
Cody looks for deeper bluffs, the ends of creeks, long points and islands. Often the fish will be stacked on the thermocline near these areas, adding that fish will often stay in one area all winter long.
Next time you are out – take a few minutes to look and try to identify a thermocline. Remember – this band of either cooler or warmer water may be narrow and by keeping your bait in this zone – you may considerably increase your number of bites. •