M.S. Marine Biology
David W. Kerstetter
Electronic pop-up satellite archival tag (PSAT) technology has been successfully used to monitor the at-large behavior of a suite of pelagic animals, especially regarding habitat utilization. Additionally, algorithms using ambient light-level data have allowed the derivation of geolocation estimates along the duration of the deployment. However, the diel behavior of swordfish moving below the photic zone during daylight hours precludes this methodology because of the lack of ambient light-level data. To produce deployment tracks for swordfish, a mathematical model was created to analyze hydrographic temperature and pressure data recorded by PSATs. This hydrographic-based model applies Principal Component Analysis (PCA) to vertical temperature profiles in order to estimate the movement between the initial location of release and the location of the first tag transmission. PSAT data from swordfish (n=4), blue marlin (n=13), white marlin (n=2), and black marlin (n=1) were used to generate daily coordinate estimates. The marlin data provided sufficient light information to derive geolocation estimates using two light-based state space models, while the hydrographic PCA model was used to derive comparison estimates. Comparisons of the two models show an average root mean square error of 174.3 km with a standard deviation of 119 km. These results demonstrate the ability of this PCA model to extract the movement of tagged fish with consistent reasonable accuracy, within 1-2 degrees of light-based estimations. This study shows the feasibility of using temperature and depth data instead of light levels to allow effective tracking of swordfish and any species that demonstrate crepuscular diving behavior.
Kathryn G. Carmody. 2014. A Principal Component Analysis of Vertical Temperature Profiles for Tracking Movements of Swordfish Xiphias gladius. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, Oceanographic Center. (37)