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Summer water temperatures and how it affects lake oxygen levels.

As air temperatures starts to warm up in mid- to late Spring, so do water temperatures. Water is warmed by the sun, so shallower waters will fluctuate more. As the day goes on, shallow water will get hotter as the sun reaches its highest point of the day, then will cool off again as the sun goes down, and the process repeats each day. Deeper water does not fluctuate temperature as much, as sunlight cannot penetrate much below the surface water. This allows water temperatures to remain cooler than shallow waters, even during hot summer months. When water temperatures start to rise in lakes, this causes oxygen concentrations to drastically vary between shallow and deeper waters, as warmer water cannot hold as much dissolved oxygen. Shallow, warmer waters will have lower dissolved oxygen compared to the deeper, cooler lake waters. It is important to note that there is a point in deep water that also has very low dissolved oxygen too, so there is a sweet spot in the deeper waters where dissolved oxygen levels are best for fish to thrive and survive in.

Because of the changes in water temperatures and dissolved oxygen concentrations, fish have daily movement patterns from shallow waters in the morning when water is still cooler, to deeper waters in the afternoon, when the shallow waters have warmed from the sun. Knowing this information can affect how anglers target fish during summer months. Summertime fishing can look a lot different than fishing during other times of the year because of where these fish might be located in the lake. Many anglers get on the water early in the morning and get off the water around lunchtime. Few anglers are out on the water during the afternoon hours – not only is it stinkin’ hot outside and unpleasant to be outdoors, but also because fish typically aren’t as active and biting. During the Summer, anglers can find fish biting out in the deeper, cooler waters where the fish are a little more active. Anglers will typically target deeper water areas that have some sort of drop off or any form of structure. Fishing with crankbaits and spinnerbaits can produce well in deeper waters.

— If you have any comments on any information related in this article, or would like more information, please reach out to Sara Menendez at sara.menendez@myfwc.com