What is water turning over related to fishing?

Answer 1

== == "Turning Over" refers to the phenomena when the warm surface water (which is Oxygen Poor) is driven downward (usually by a cold hard rain after a long drought) and the colder oxygen rich waters are forced closer to the surface. Fish instinctually move to lower water depths to find more oxygen, and when the water has turned over, they find oxygen poor waters and can die of asphyxiation. Turnover does in fact refer to a mixing of warm surface waters and cold bottom waters, but actually, it is the surface waters that are oxygen rich, and bottom waters which are oxygen poor. In a lake, for example over the course of a long summer, sunlight will penetrate the surface waters, resulting in natural production of algae (phytoplankton). The phytoplankton are responsible for most of the oxygen in a lake. But as the algae becomes more productive, it shades out the lake, preventing sunlight from penetrating deeply. From the surface of the water down to the point where only the tiniest bit of light remains is called the photic zone. It is ONLY in this zone that photosynthesis can occur, and therefore oxygen production. In the bottom waters, where there is no sunlight, there is no photosynthesis and therefore no oxygen production.

Furthermore, the sunlight is the only natural source of heat. So the photic zone becomes warmer as the summer goes on, while the bottom waters, which are not sunlit, stay cool. Warmer water is less dense than cold water and so the warm water floats on top of the cold water. This is called thermal stratification. So when there is a cold hard rain at the end of a long summer, the cold rain falls into the surface waters, cooling it down. When surface waters get close enough to the temperature of bottom waters, the water column will become mixed, resulting in turnover. So the short answer to your question is, turnover is NOT related to fishing. LOL.