Satellite tag attachment methods for tracking neonate sea turtles

Abstract

Significant gaps exist in our understanding of early sea turtle life stages. Dispersal and habitat use of young oceanic sea turtles are largely inferred. Historically, available tracking technology and tag attachment methods were limited by small body sizes and rapid growth of neonate sea turtles. We tested methods in the laboratory for attaching small solar-powered satellite tags to neonate loggerhead sea turtles Caretta caretta, including harnesses, hard epoxy and neoprene-silicone mounts. Non-harness attachments were tested on turtles with clean carapaces and carapaces treated with an acrylic base-coat. Turtle growth and condition were measured among treatment and control groups. We tested surrogate solar cells, coated with clear silicone antifoulant for biofouling and performance, and field tested the performance of 7 solar-powered satellite tags on neonate loggerheads released off southeastern Florida (USA). Attachments with acrylic base-coats remained affixed 4-to 8-fold longer than on untreated carapaces. Harness attachments resulted in long-term tag retention (> 60 d). However, harness and hard epoxy attachments did not adjust for turtle growth; we do not recommend these methods for rapidly growing neonate turtles. The method with longest retention was a neoprene-silicone attachment on an acrylic base-coat. Growth and condition were comparable among treated and control turtles using this flexible neoprene-silicone-acrylic attachment. Field-tested tags transmitted for 38 to 172 d. There were significant differences in charge rates of tags treated with an antifoulant and untreated tags; however, all tags charged optimally and transmitted high-quality locations. Our data suggest that small solar-powered tags are viable tools for monitoring the in-water behavior of oceanic sea turtles.

Comparing Acoustic Tag Attachments Designed for Mobile Tracking of Hatchling Sea Turtles

“…Any object placed on an organism adapted to live in its environment may affect its natural behaviours and increase its energetic costs. Consequently, an objective of this methodology was to provide appropriate consideration to the development of tag attachments for leatherback turtles that minimize these negative effects and extend beyond controlled tank environments (Mansfield et al, 2012;Jones et al, 2013). Given that the oily, rubbery skin of leatherbacks could reduce adherence, we wanted to test two attachment techniques in case there were conditions in the field that made a particular method less effective.…”

“…The inability to access at-risk sea turtles resulted in a low sample size. Mansfield et al (2012) utilized an ANOVA framework with smaller sample sizes on sea turtles, and our sample size is within the generally accepted size for this statistical test. While a larger sample size could theoretically increase statistical robustness, this was not feasible given available turtles at the time, and data corrections were applied to meet all model assumptions.…”

“…Hatchling sea turtles tagged with miniature acoustic tags generally meet this requirement (Thums et al, 2013(Thums et al, , 2016Scott et al, 2014), but the influence of tag attachments on animal behaviour should still be carefully considered prior to field studies on threatened and endangered species (Vandenabeele et al, 2012). An examination of movement metrics, such as speed and diving depth, should be undertaken prior to deploying transmitters on wild turtles to ensure that the tracking process is unlikely to decrease fitness or survival, whilst providing biologically representative information (Casper, 2009;Mansfield et al, 2012;Jones et al, 2013). A direct attachment method on the plastron has been developed for flatback (Natator depressus), green (Chelonia mydas), and loggerhead (Caretta caretta) hatchlings (Thums et al, 2013(Thums et al, , 2016Scott et al, 2014).…”

Tagging through the stages: technical and ecological challenges in observing life histories through biologging

“…Improvements in biologging technology have resulted in substantial tag miniaturization and enhanced data compression (Fedak et al 2002). Although it is now possible to attach small tags to young animals (Mansfield et al 2012), the small size of these tags limits the number of sensors and length of battery life. Thus, it is essential that careful thought goes into what research questions need to be answered and what types of, and how much, data need to be collected to answer these questions (Breed et al 2011).…”

“…Young life stages tend to grow rapidly, often requiring attachment methods that are flexible enough to accommodate growth. Assessment in the field or laboratory of suitable attachment methods is necessary to ensure that any tagging effort has minimal impact on the animals and that the benefits of tagging are not outweighed by the costs (Wilson & McMahon 2006, Mansfield et al 2012.…”