New insights on sea turtle behavior during the ‘lost years’
Data files
Jan 06, 2025 version files 6.05 MB
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drifter_location_data_forSSM.xlsx
5.38 MB
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lost_years_SSM.R
3.25 KB
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README.md
3.10 KB
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turtle_location_data_forSSM.xlsx
660.78 KB
Abstract
Several marine turtle species spend their first years of life in oceanic habitats. This early life stage is referred to as the “lost years” due to the difficulty of accessing individuals for study offshore. We satellite tracked 114 wild-caught juvenile turtles (straight carapace lengths 12.3-29.9 cm) from the Gulf of Mexico between 2011-2022 to investigate “lost years” movements with respect to traditional definitions assigned to the life stage. Satellite-tracked turtles included 79 green turtles (Chelonia mydas), 26 Kemp’s ridleys (Lepidochelys kempii), 5 loggerheads (Caretta caretta), and 4 hawksbills (Eretmochelys imbricata). Many tracked turtles transited between oceanic (>200 m depth) and neritic waters (<200 m depth), challenging the assumption that this life stage is exclusively found in oceanic habitats. Turtle movements differed from oceanographic surface drifters, providing further evidence that sea turtles of this life stage do not exclusively drift with currents. We recommend redefining the “oceanic stage“ as a “dispersal stage“ to better reflect their behavior and habitat plasticity. Our findings establish the West Florida Shelf as a high-use area, particularly among green turtles and Kemp’s ridleys. The northeastern Gulf of Mexico is an important region for these species of conservation concern.
README: New insights on sea turtle behaviour during the 'lost years'
https://doi.org/10.5061/dryad.stqjq2cc2
Description of the data and file structure
Files and variables
File: lost_years_SSM.R
Description: R script to format telemetry data files and then use the bsam package to estimate positions at a 12-hour timestep and estimate behavioral states.
File: turtle_location_data_forSSM.xlsx
Description: Excel file with individual sea turtle locations, Argos tag IDs, time/date of location received, and Argos location codes. There are 112 individuals in the dataset, as two tracked turtles were not included in the state space model analysis: one green turtle with an 8-hour tracking duration too short for the 12-hour model timestep, and one green turtle with a 7-day transmission gap that failed to converge.
Variables
- Species: Lk= Kemp's ridley, Cc = loggerhead, Cm = green turtle, Ei = hawksbill
- Tag_id: Argos tag IDs for each tag deployed (individual identifier)
- utc: Date and time in Coordinated Universal Time for each position/location received from satellite tag
- lc: Argos location class (see below)
- Lat1: Latitude, decimal degrees
- Dir1: North (N) or South (S) latitude
- Lon1: Longitude, decimal degrees
- Dir2: West (W) or East (E) longitude
Argos location classes (lc) are defined as:
lc 3: estimated error < 250m
lc 2: estimated error 250m-500m
lc 1: estimated error 500m-1500m
lc 0: estimated error > 1500m
lc A: No accuracy estimation
lc B: No accuracy estimation
lc Z: Invalid location
File: drifter_location_data_forSSM_(1).xlsx
Description: Excel file with oceanographic drifter IDs, GPS positions, and the associated dates/times
Variables
- ESN: individual drifter ID; Electronic Serial Number from each GPS tracking device
- Message Time GMT: date and time (recorded as Greenwich Mean Time) for each location received
- Latitude and Longitude (in decimal degrees).
Code/software
The free software to run the code: R, which is available for download at https://www.r-project.org/
Access information
Other publicly accessible locations of the data:
- n/a; an early subset of the data was included in the following citation:
Putman, N.F. and K.L. Mansfield. 2015. Direct evidence of swimming reveals a new paradigm of dispersal in the sea turtle ‘lost years’. *Current Biology, *25, 1-7. DOI: http://dx.doi.org/10.1016/j.cub.2015.03.014. Open archive.
Data were derived from the following sources:
- n/a
Methods
Location data for juvenile sea turtles in the Gulf of Mexico were collected via satellite telemetry. We deployed oceanographic surface drifters with each turtle release against which to compare turtle movements. State space models were run in R. Full methods available in published manuscript. DOI: https://doi.org/10.1098/rspb.2024.2367