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Inter Research, Endangered Species Research, (10), p. 245-254

DOI: 10.3354/esr00164

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Movements of olive ridley sea turtles Lepidochelys olivacea and associated oceanographic features as determined by improved light-based geolocation

Journal article published in 2009 by Yonat Swimmer, Lianne McNaughton, David Foley, Lucas Moxey, Anders Nielsen ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

We demonstrate the use of pop-off satellite archival tags (PSAT)-derived geolocations to determine the most probable tracks (MPTs) of olive ridley sea turtles Lepidochelys olivacea off Costa Rica. We use a Kalman filter state-space model (KFSST) that uses light-based longitude and latitude and sea surface temperatures (SST). PSATs placed on 14 turtles remained fixed for an average 53 d (range: 29 to 111 d). The average reduction in longitude and latitude standard deviations was ϕlon = 0.62 and ϕlat = 0.28 between the raw and KFSST-derived MPTs, respectively. Geolocations were linked in time to oceanographic features such as SST and chlorophyll a, as reported by satellite-based sensors. Turtles went in all directions from their respective release points, independent of year and capture type (longline-caught vs. hand-caught). Turtles remained within a SST range between 23.3 and 30.5°C (mean = 27.1°C), with over 75% of all recorded temperatures between 25.0 and 28.0°C. Turtle locations were associated with mean chlorophyll a = 0.37 mg m -3 . MPT data suggest that tur- tles spent a disproportionate amount of time in the general region of the Costa Rica Dome, a nutrient- rich quasi-permanent cyclonic eddy. Taken together, these findings support the increased utility of filtered light-based geolocation data in identifying environmental features characteristic of sea tur- tles' preferred habitat, information which can be useful in managing regional fisheries.