DOI: 10.5061/dryad.jh9w0vtmq
title: Data from: Assessing the impacts of satellite tagging on growth rates of immature hawksbill turtles

description: Animal-borne devices including transmitters, data loggers, and
 identification tags are widely used across taxa to address important
 biological and ecological questions. Some of these devices may affect
 fitness, hence studies to assess device impacts are important across taxa
 and developmental stages. We assessed the impact of satellite tagging on
 sea turtles at a foraging site in the Indian Ocean. Hawksbill turtles
 (Eretmochelys imbricata) were captured, and satellite tags (Fastloc-GPS
 Argos) attached to 25 individuals between 2018-2021, with a mean straight
 carapace length (SCLn-t) of 55.3 ± 6.9 cm (range = 47.9-69.5 cm; N = 21).
 We recaptured 12 tagged turtles and removed 11 tags between 2021-2023 and
 estimated growth rates of tagged (N = 10) and untagged (N = 44) animals
 (mean SCL range = 33.3-69.4 cm) using capture-mark-recapture of 54
 individuals at liberty for 730-1095 days. Growth rates decreased
 exponentially as turtle size increased, and we found no significant
 difference between tagged and untagged growth rates and body condition. We
 also found no damage to the carapace from the tag attachment. We suggest
 that tagging does not impact growth rates at this study site because the
 turtles (i) typically maintain small home-ranges in the lagoon and (ii)
 are benthic feeders, not actively pursuing prey. We encourage best
 practice to study the effects of satellite tagging on turtle populations
 around the world, as the outlook may be different for animals that swim
 long distances and/or carry large devices.
description: # Data from: Assessing the impacts of satellite tagging on growth rates of
 immature hawksbill turtles
 [https://doi.org/10.5061/dryad.jh9w0vtmq](https://doi.org/10.5061/dryad.jh9w0vtmq) ## Description of the data and file structure *Study site and capture-mark-recapture* Research took place in the Chagos Archipelago. Between 2018 and 2023, immature hawksbill turtles were captured (*N* = 199 individuals on 331 occasions) as part of a long-term in-water sampling program underway between 1996 and the present. We waded in shallow water at low tide (&lt; 0.5 m) and quietly approached turtles from behind whilst they were feeding and captured them by hand. At first encounter, each turtle was flipper tagged on both front flippers using Inconel (National Band and Tag Company, KY, USA) tags, and biometric measurements were taken. During subsequent recaptures, turtle tags were recorded, missing tags replaced as needed, and measurements repeated.  These included curved carapace length (cm) notch-to-tip (CCLn-t, hereafter CCL; Bolten, 1999) using a flexible measuring tape, straight carapace length (cm) notch-to-tip (SCLn-t, hereafter SCL; Bolten, 1999) using vernier callipers, and mass (kg) using a spring balance. Mean mass divided by mean SCL cubed was used as a metric for body condition (mass/SCL3; Marn et al., 2019). If satellite tagged, the turtle was examined and photographed for evidence of damage at the attachment site on the carapace. Observations were recorded. *Satellite tagging* Satellite tags with Fastloc-GPS (SPLASH10-BF-297B-01, Wildlife Computers, Seattle, Washington, USA) were attached to 25 hawksbill turtles between 2018-2021. Length x width x height dimensions of the tags were 8.6 x 5.5 x 2.6 cm and their mass in air was 130 g (&lt; 1.2 % total body mass of the smallest tagged turtle) and approximately 10 g in seawater (i.e., negatively buoyant). Satellite tags were only attached to individuals with a CCLn-t &gt; 50 cm. As immature turtles in Diego Garcia lagoon generally show high fidelity to their foraging grounds (Hays et al., 2021), recaptures of the same individuals were frequent. Turtles were considered immature based on classification of immature hawksbills at other sites in the south-west Indian Ocean (e.g., Seychelles; &lt; 80 cm CCL; Sanchez et al., 2023). Tags were removed if there were signs of detachment from the carapace, for example, the epoxy was weak along the edges. To compare tagged and untagged individuals we filtered the data to reflect tagged turtle recapture intervals which were between 2-3 years (730 – 1095 days), and so all untagged turtles were only included if recaptures occurred between 730 – 1095 days. We plotted growth rates against SCLn-t rather than CCLn-t, as we more frequently had SCLn-t measurements at both capture and recapture (*N* = 10). ### Files and variables #### File: Data\_Fig1\_2\_SI2\_Assessing\_impacts\_satellite\_tagging\_growth\_rates\_immature\_hawksbill\_turtles.xlsx **Description:** Data used to create figures 1, 2 and SI 2. Immature hawksbill growth rate data (*N* = 54). Includes the initial capture date (dd/mm/yyy), recapture date (dd/mm/yyyy), tag number attached to the right turtle flipper, tag number attached to the left turtle flipper, initial straight carapace length (SCL, cm), recapture straight carapace length (SCL, cm), initial mass (kg), recapture mass (kg), tag or no tag on recapture.  #### File: Data\_FigureSI1\_Assessing\_impacts\_of\_satellite\_tagging\_growth\_rates\_immature\_hawksbill\_turtles.xlsx **Description:** Data used to create figure SI 1. Curved carapace length and straight carapace length relationship. Includes the date of capture (dd/mm/yyyy), tag number attached to the right turtle flipper, tag number attached to the left turtle flipper, curved carapace length (CCL, cm), straight carapace length (SCL, cm). ## Code/software All analyses were conducted in the free software R.