Mosquito Control District Programs

The St. Lucie County Mosquito Control District is funding a study by the Marine Resources Council of East Florida, Inc. titled Sportfish Utilization of an Indian River Lagoon Seagrass Flat Adjacent to Managed Mosquito Control Impoundments. One aspect of this study involves monitoring the spawning of spotted seatrout in the vicinity of the study area off of impoundments 14A and 14B by using a portable hydrophone to record the sounds made by the male fish to attract the females to mate and spawn. Biweekly (close to new and full moon) surveys, between sunset and midnight, are performed during the prime spawning season of May -September. The procedure entails stopping at a sampling site (an ICW channel marker or other known location), submerging the hydrophone to a depth of approximately 1m, and recording for 3 to 5 minutes while monitoring the sounds with headphones. The recordings are later interpreted using sound analysis software and/or a graphic equalizer to filter the higher frequencies and allow good estimation of calling group size. Large numbers of calling seatrout have been recorded in the survey area, confirming that it is a regionally important spawning location.

The following data was collected by Brian Barnett of Vero Beach, Florida:

Spectrogram of Calling Spotted Seatrout

*Above trout image from the Fish and Wildlife Research Institute