Behavioral Response of Select Reef Fishes to Mid-Frequency Sonar

There is growing concern over the potential effects of high-intensity sonar on natural fish populations and commercial fisheries.  Acoustic telemetry was employed to measure fine- and regional-scale movement of free-ranging reef fish in Port Canaveral, Florida, in response to submarine sonar testing.  Twenty-five sheepshead (Archosargus probatocephalus) and 28 mangrove snapper (Lutjanus griseus) were tagged and monitored for a period of up to four months.  Receivers were deployed within Port Canaveral to complement an existing array of compatible receivers along the east coast of Florida.  Baseline residency, diel patterns of movement, and centers of activity were examined for fish before, during, and after the test event.  No fish mortality was associated with the event.  There was a significant increase in daily residency index for both sheepshead and snapper at the testing wharf after the event.  Additionally, there was a significant decrease in hourly residency index for sheepshead during the test at receivers furthest from the source compared to before the test.  Varying patterns of response were seen in individual fish, with some abandoning the portion of the wharf closest to the sonar source, while other fish either showed no change in space use or shifted activity to locations on the wharf further from the source.