Dynamics. by Mark Thomson
how environmental conditions can effect a lake is fundamentally
important to all freshwater anglers. For many, thermoclines are
one of the best places to find bass in stable weather and water
conditions. But if conditions change, we don't have the luxury
to easily locate good water provided by the thermoclines. I believe
that seasonal weather patterns and water levels play a significant
role in how anglers can locate fish in dams, the angling methods
they use are dictated by the depth that the fish are located.
It helps to be able to combine a little science, and different
fishing skills to be successful.
The following is my interpretation on how thermoclines in particular
change though seasons and under changing water levels. I interpret
this from literature and on-the-water experiences over the last
dynamics through the seasons
In spring thermoclines are small in size and are distributed
throughout the stratified depths of a lake. Bass tend to concentrate
in large schools at this time of year and take advantage of the
deep water refuge and food conditions available in these small
Summer: During summer an improvement of weather conditions
enhances and expands the size and occurence of thermoclines in
a lake. Aquatic life and bass will utilize the expanding presence
of thermoclines and tend to distribute over greater areas of the
Winter: Winter will see the reduction of thermoclines to
only a handfull of suitable areas of the dam. In fact, thermoclines
will only remain in areas of deep water and in the more sheltered
or protected parts of a lake that do not turn over.
Lake Turn-over: This is an event where lakes epilimnion
tilts and mixes the hypolimnion below, destratification occurs
disturbing and mixing water conditions. This event is a common
occurrence in temperate lakes that experience long periods of
very cold weather. It may affect all or part of a lakes area thus
reducing or eliminating the occurrence of thermoclines.
Rain and Flooding: A major rain or flood event will also
cause major mixing and destratifaction of water in a lake. Unstable
water conditions now prevail throughout the lake reducing or eliminating
thermoclines. With the lake now full of water and destratified,
water conditions are relatively homogenous offering similar oxygen,
temperature and P.H. conditions throughout.