Pop-up Satellite Archival Tag (PSAT) Tagging of Two Lemon Sharks (Negaprion brevirostris) in the Florida Straits within an Acoustic Tagging Network

Little is known about the seasonal aggregations of lemon sharks off the southeastern Florida coast, but studies are underway to investigate the specific environmental cues that instigate the aggregation formation or the behavior of individuals within the aggregation. An acoustic telemetry system has been in place since early 2007 to monitor movement patterns, but this system will only record presence or absence of an individual. To facilitate the acoustic study and the investigation of habitat utilization, two lemon sharks were simultaneously tagged with acoustic transmitters and 10 d, high resolution PSATs. This combination provides additional information on habitat utilization through the pairing of local behavior data with ambient environmental data from the acoustic system. The first PSAT transmitted after only a 7 d deployment, i.e., prior to the expected date. Analyses of the tag status data indicate that the “constant depth” trigger to the automatic release programming was activated. Although these depth data would normally suggest a mortality event, the acoustic system recorded hits between 21 receivers during an additional 480 d following PSAT release, indicating survival. The second PSAT transmitted data on schedule. Both tagged animals exhibited significant changes in behavior 3 d after release, with numerous, short duration vertical movements during both day and night periods within a 50 m range during the first 3 d and only 15 m during the remainder of the respective tracks. The use of electronic monitoring devices in combination should be used when possible to provide complementary data streams from difficult to tag organisms.