DOI: 10.5061/dryad.stqjq2cc2
title: New insights on sea turtle behavior during the ‘lost years’

description: 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 (&gt;200 m depth) and neritic waters
 (&lt;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.
description: 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
description: # New insights on sea turtle behaviour during the 'lost years'
 [https://doi.org/10.5061/dryad.stqjq2cc2](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 &lt; 250m lc 2: estimated error 250m-500m lc 1: estimated error 500m-1500m lc 0: estimated error &gt; 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/](https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.r-project.org%2F&data=05%7C02%7CKate.Mansfield%40ucf.edu%7Cd269290187744c8fb49a08dce23e5aa7%7Cbb932f15ef3842ba91fcf3c59d5dd1f1%7C0%7C0%7C638634004664537945%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=HVgemle1OM8yfqM8psmlmiqy9%2Ff8X%2Bxr5sDTs0EPOuo%3D&reserved=0 "Original URL: https://www.r-project.org/. Click or tap if you trust this link.") ## 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](http://dx.doi.org/10.1016/j.cub.2015.03.014). Open archive. Data were derived from the following sources: * n/a