Assessing Temperature and Depth Selection of Trophy Bass: a Case Study at Kingsley Lake

by Drew Dutterer

In December 2015, FWC researchers launched a unique bass telemetry study at Kingsley Lake, in Clay County. Kingsley Lake stands out for two reasons — it is exceptionally deep for a Florida Lake (max depth 82’, ~300 acres ≥ 40’ deep), and it is home to an abundance of exceptionally large Florida Bass (Micropterus floridanus). Each year dozens of trophy bass, equal or greater than 8 lbs, have been reported from Kingsley to TrophyCatch, FWC’s citizen-science, trophy-bass conservation program. The lake has produced 14 of the program’s Hall-of-Fame bass(≥ 13 lbs), more than any other of Florida’s 7,700 waterbodies; and four of the top five heaviest bass documented by the program were from Kingsley.

A FWC researcher makes an incision to implant an acoustic telemetry transmitter into the body cavity of a Kingsley Lake bass.

The working hypothesis that attempts to explain Kingsley Lake’s unique bass population is the thermal stratification of the water column offers a cool-water refuge to bass during summer. Therefore, their metabolism is mediated, which could lead to faster growth, lower natural mortality or both. The researchers’ primary objective is to confront this hypothesis by implanting trophy bass with temperature- and depth-sensor acoustic transmitters and recording their spatial, depth, and temperature selection patterns for two years.

This bathymetric map of Kingsley Lake was generated from sonar recorded by FWC researchers at the start of this project. The contour lines show three-foot depth increments. The maximum depth is 82 feet, and most of the internal sub-basin is ≥40 feet deep.

Researchers implanted transmitters into 10 Kingsley Lake bass ranging in size from 9 to 13 pounds in December 2015 and January 2016. By combining frequent transmitter measurements (every 90 seconds), a lake-wide acoustic receiver array, and post-processed signal triangulation, the researchers will maintain near-continuous three-dimensional tracking of telemetered bass. Conditions throughout the water column available to bass will be recorded continuously through a series of temperature and dissolved oxygen loggers.

In the end, researchers will have extremely detailed data showing how members of Kingsley’s unusual bass population relate to their environment regarding temperature and depth. Ultimately, this study aims to reveal more information about how environmental factors influence bass growth, furthering our understanding of bass biology and bioenergetics.