By midsummer, many lakes in the Carolinas stratify according to oxygen content, and that sets up conditions that give fisherman an edge if they understand the process, namely, a thermocline.

Guide Chris Nichols uses this to his advantage on several lakes for summer fishing. 

“Using a graph, the water transition from warm water in the upper layer to the cold, dense, deeper water is visible on the graph. Below that, the dissolved-oxygen level is too low to support fish for extended periods.

“Catfish, and other fish species, spend most of their time at depths where the oxygen level is higher,” he said. “Many anglers reason that hot weather and deep water offer the right combination for summer; actually that’s not always true. 

“Catfish may go deeper for brief periods, and we occasionally catch them deep. By targeting this upper level of highly oxygenated water, I increase my catch tremendously. The fish get close to the thermocline, but not below it for long. The thermocline sets up at different depths in each lake, but you can see it on a good graph. Target the depths at and just above the thermocline and your catfish production will improve dramatically.”