Hypoxia can occurs when dissolved oxygen levels dip below 3 to 4 ppm in water.
The Striped Bass needs Dissolved Oxygen levels over 5
parts per million (ppm).
Preference is between 8.1 - 10.1 (PPM) with the peak activity around 9 (PPM).
Temperature preference between 50 and 75 degrees.
Oxygen (DO) refers to the level of free, non-compound oxygen present in water or other liquids.
It is an important parameter in assessing
water quality because of its influence on the organisms living within a body of water.
In limnology (the study of lakes), dissolved oxygen is an essential
factor second only to water itself.
Temperature limits the amount of oxygen water can hold.
So in general, summertime Lake Ouachita water hold less oxygen than can
During hot weather the water
becomes stratified, or divided into several layers, with the upper layer being
the warmest and highest in oxygen.
The largest impact on striped bass often
occurs in late summer (August and September) when water temperatures are highest
and DO values are lowest.
Deeper levels are cooler but contain less dissolved oxygen.
This will generally
occurs during the latter part of the summer and varies in magnitude from year to
As summer progresses, the upper layer becomes too warm for stripers, which
prefer water less than 78 degrees, and the fish move to deeper and cooler waters
where the best balance of cool temperatures and high levels of oxygen are found.
As the Dissolved oxygen levels in the lower layers are depleted to
around 3 ppm, the suitable habitat for the striped bass is reduced, they
become stressed will sometimes quit feeding and maybe die.
Stripers caught during this time of the year should not be released.
As the summer sun continues to warm the lake, the surface temperature
increases between the surface (epilimnion) and deeper waters (hypolimnion).
The temperature differences eventually create a physical called
stratification (the formation of layers), water temperatures decrease from
the surface to the bottom
The lake now stratifies into three
layers of water a situation termed summer
The upper layer is a warm
(lighter), well-mixed zone called the epilimnion.
Below this is a
transitional zone where temperatures rapidly change called the metalimnion.
The layer of rapid temperature change separating the two layers is called
The lake's temperature variations are
important in influencing what types and how many fish will live and
reproduce in the lake.
IF the colder, deeper waters of the
hypolimnion have enough oxygen, then that area will provide a refuge for
fish species that prefer, or require, cooler water temperatures.
if dissolved oxygen levels become too low in the cooler hypolimnion zone and
fish are forced into the warmer surface waters, Stipers may not be able to
Water temperature is one of the most significant factors to rely on when trying
to locate and catch Striped Bass.
As water temperature changes throughout the
year, so does fish behavior and metabolism.
Learning to identify how Ouachita
changes and how stripers adapt to these changes can improve your success.
Fishing for Striped Bass during the end of the summer months is often
frustrating because warm water temperatures can make finding and catching fish
difficult. And sometimes when you do find them they won't eat.
In early fall a precursor to the fall turnover is when upper
water temperature drops into the 75° F range.
Pre-turnover water temperatures instinctively cue fish that winter is coming and
feeding activity increases
What is fall turnover?
It’s a process that breaks down the stratification, or layering, of warm surface
waters above cool or cold deeper waters that occurs in lakes during the summer.
During the summer, mixing only occurs in the uppermost layer of water.
turnover occurs as surface waters cool, become more dense than underlying
layers, and sink, thereby pushing the underlying water layers to the surface.
This mixing action occurs until all water is the same temperature from surface
Dead zones and DO levels can vary widely from year to year, and habitat
preferences of stripers depend on more than just DO levels.
The USGS Water
Nathan G. Smith, Texas Parks and Wildlife Department:
bass are vulnerable to high summer water temperatures and low dissolved
oxygen (DO) in southern reservoirs, potentially resulting in poor body
condition and elevated mortality.