Americana Outdoors E-Magazine - August 2022

Queen’s University and the Natural Science and Engineering Research Council of Canada. Most recently, a research project funded by ten state fisheries agencies conducted at Mississippi State University evaluated the effects of water temperature, livewell temperature and dissolved oxygen, and fish landing time on largemouth bass survival. This study took a practical approach of duplicating actual conditions that largemouth bass face during a tournament from catch, to livewell holding, to weigh-in, to release back into the water. Survival was measured after 8 hours of livewell retention and for five days after weigh in. Under controlled conditions, adult bass were then subjected to angling times of 1 minute and 3 minutes, 8 hours in a livewell at dissolved oxygen concentrations of 2, 5.5 and 8.5 parts per million (ppm), and livewell temperature of no change in temperature, cooling the water 7 degrees F, or warming the water 7 degrees F. All trials were conducted at temperatures ranging from 63 to 91 degrees F to fully represent the temperature conditions when most bass tournaments occur. MSU Study Summary Fight times, handling, low dissolved oxygen, and warm water impact survivability. Catch and release tournaments have minimal effect on survival if fish are landed quickly, handled properly, and kept in livewells with quality water at 84 degrees or less. WATER TEMPERATURE It is always best to maintain water temperatures in the livewell and at the weigh-in site as close as possible to (or slightly below) the temperature where the fish came from. Fish are “cold blooded” animals, so their body temperatures are not regulated internally but rather by the water temperature around them. Depending on the time of year and ambient temperature in the lake, the optimum temperature for largemouth bass is below 84 degrees.

The MSU study confirmed that at 91 degrees, livewell water temperature is a serious problem for bass. You want to keep the temperature in your livewell close to the water temperature the fish came out of. It is important to remember that the temperature gauge on your boat is reading the water temperature near the surface, and your bass may have been living at a depth with a lower temperature than you show on your boat. Once the livewell temperature reaches 84 degrees, keep it from getting any warmer by cooling it down with ice. Sudden temperature change of more than 7 degrees can be harmful to largemouth bass. To allow for longer, slower cooling of the water in your livewell, use block ice if available, or freeze water in a plastic bottle or another container and place in the livewell. Keep frozen plastic water bottles in your ice chest, so you can place them in your livewell to cool water as needed. At the weigh-in, fill your weigh-in bag with cooled water from your livewell rather than dipping in warm lake water.

PRO TIP #1 Water temperature is the most important factor in bass survival. Maintain temperatures of no more than 84 degrees in your live well and weigh bag. Keep frozen water bottles in your ice chest to use for cooling the water as needed.