Wednesday, January 19, 2011

Fish Population 1/19/11

As you may have noticed as you play golf, we have a portion of the fish population expiring currently.  This unfortunately is an annual event that we experience about this time every year.  This is a fairly specific problem localized to the Tilapia species.  When atmospheric conditions become correct each year it causes the lakes to “turn over.”  When that occurs it fluctuates the environment in the water enough that it causes the weaker fish to expire.  The science surrounding this annual occurrence as I understand it is as follows.  Each year when atmospheric conditions are correct it causes the water on the surface to be "much warmer" than the water below causing layering or "stratification."  This causes 2 distinct things: more oxygen in the warmer surface water than the cooler water below (this is a strange event in itself as typically cooler water holds more oxygen) and it insulates the cooler water below.  The reduction in dissolved oxygen below causes a "stress" situation.  Then when conditions are correct and the top warm water is mixed with all water during "turn over" lowers the overall temperature of the lake.  Tilapia are very sensitive to temperature and this drastic temperature change will cause death in weaker "stressed" fish.  In extreme cases if the "turn over" lowers the temperature near 60 degrees even healthier fish can be in jeopardy.

Each year we gather these fish daily and place them in containers.  At the end of this event each year Arizona Fish and Wildlife collects them from all area properties for disposal.

This event has nothing to do with any practices we utilize to maintain the property.  While not a specialist, it has more to do with size of the body of water, water temperature, atmospheric conditions and the specific ecological environment in the particular body of water.

Kindest regards

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