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FWRI biologists log summer time temperatures to better understand Florida’s yellow perch populations.

  • Biologists monitored water temperatures for 12 months in Dead Lakes and Stone Mill Creek, Florida
  • During the summertime months (June–September) the Stone Mill Creek area showed noticeably cooler temperatures with an average monthly temperature ranging from 77.4⁰–79.0⁰ F, compared to 82.0⁰–85.3⁰ F in the main Dead Lakes section
  • We believe Stone Mill creek provides a cool water refuge to help alleviate stressful thermal conditions for Yellow Perch populations.

In Florida, Yellow Perch are only known to exist in limited populations throughout the Apalachicola River watershed, with reproducing populations in Lake Seminole and the Dead Lakes, the southernmost known population in the United States. Prior studies have shown the importance water temperature has on Yellow Perch populations and with higher temperatures in the south east, the summer months can be stressful for the fish.

In 2015 and 2016, biologists found high concentrations of Yellow Perch in the Stone Mill Creek section of the Dead Lakes. Stone Mill Creek is a spring-fed creek that flows into West Arm Creek and ending in the main Dead Lakes section. In 2015, biologists monitored water temperatures for 12 months in the Dead Lakes, to identify temperatures Yellow Perch experience throughout the year and temperature impacts of Stone Mill Creek.

Biologists set temperature data loggers–one at the mouth of Stone Mill Creek and one in the main Dead Lakes section. Using a weight and rope, the temperature loggers were placed at or near the bottom of the lake and tethered to a cypress tree for easy retrieval. The loggers were set to record water temperature four times a day (12:00 am, 06:00 am, 12:00 pm, 06:00 pm).

During the summertime months (June–September) the Stone Mill Creek area showed noticeably cooler temperatures with an average monthly temperature ranging from 77.4⁰–79.0⁰ F, compared to 82.0⁰–85.3⁰ F in the main Dead Lakes section.

Furthermore, in the main Dead Lakes section, 25% of summertime days (June–September) recorded temperature at or above 86.0⁰ F with a maximum recorded temperature of 90.9⁰ F (September 2015); whereas, Stone Mill Creek had a maximum recorded temperature of 83.8⁰ C (July 2015).

Studies have shown that lethal temperature for Yellow Perch range from 89⁰–93⁰ F (Hart 1952, McCormick 1976). The main Dead Lakes section showed high average summertime temperatures with some daily temperatures reaching lethal levels (> 89⁰ F), whereas, the Stone Mill creek section never reached lethal levels. We believe Stone Mill creek provides a cool water refuge to help alleviate stressful thermal conditions for Yellow Perch populations.

Aerial outline of Dead Lakes located in the panhandle of Florida. Sampling was conducted in the West Arm of Dead Lakes and Stone Mill Creek (shaded in grey). The red markers in Stone Mill Creek and main Dead Lakes represents the locations where temperature data loggers were placed.