NMFS Turtle Tracking

Keywords: Occurrence,Radio transmitters,Animal movements,Turtles,Longline fisheries interactions,Loggerhead,Olive ridley,Habitat, Observation, Occurrence
Temporal coverage: 1997/2013

Original provider:
NOAA Pacific Islands Fisheries Science Center (PIFSC)

Dataset credits:
NOAA Pacific Islands Fisheries Science Center (PIFSC)

Abstract:
Satellite telemetry from 26 loggerhead (<i>Caretta caretta</i>) and 10 olive ridley (<i>Lepidochelys olivacea</i>) sea turtles captured and released from pelagic longline fishing gear provided information on the turtles' position and movement in the central North Pacific.
These data, together with environmental data from satellite remote sensing, are used to describe the oceanic habitat used by these turtles. The results indicate that loggerheads travel westward, move seasonally north and south primarily through the region 28-40 deg N, and occupy sea surface temperatures (SST)
of 15-25 deg C. Their dive depth distribution indicated that they spend 40% of their time at the surface and
90% of their time at depths &lt;40 m. Loggerheads are found in association with fronts, eddies, and geostrophic
currents. Specifically, the Transition Zone Chlorophyll Front (TZCF) and the southern edge of the Kuroshio Extension Current (KEC) appear to be important forage and migratiom habitats for loggerheads. In contrast, olive ridleys were found primarily south of loggerhead habitat in the region 8-31 deg N latitude, occupying warmer water with SSTs of 23-28 deg C. They have a deeper dive pattern than loggerheads, spending only 20% of their time at the surface
and 60% shallower than 40 m. However, the three olive ridleys identified from genetics to be of western Pacific origin spent some time associated with major
ocean currents, specifically the southern edge of the KEC, the North Equatorial Current (NEC), and the Equatorial Counter Current (ECC). These habitats were not used by any olive ridleys of eastern Pacific origin suggesting that olive ridleys from different populations may occupy different oceanic habitats.

Purpose:
To determine movements of loggerheads throughout the Pacific ocean and to define their oceanic habitat.

Supplemental information:
Track data from 2000 till 2013 were added in August 2015. During this process, the following changes were made.
- Some of the field names were changed (e.g. series =&gt; argos_id, lc_code =&gt; lc)
- SCL, CCL, Sex and Weight attributes were added. SCL, Sex and Weight are empty for data before 2000, though.
- Tag ID was modified by adding the last two digits of the year the tag was deployed.

The following errors were found and fixed.
- The time values of 19588_97 and 19589_97 were in a wrong format and invalid. The time values were refilled.
- The time value of 19582_97 on 6/13/1997 was corrected to 01:36:00.
- The time value of 25315_00 on 05/13/00 was corrected to 20:13:00.

Additional reference: <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073274">Abecassis, M., I. Senina, P. Lehodey, P. Gaspar, D. Parker, G. Balazs, and J. Polovina. 2013. A model of loggerhead sea turtle (<i>Caretta caretta</i>) habitat and movement in the oceanic North Pacific. PLoS ONE 8:e73274.</a>