Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre

Abstract

Leatherback sea turtles (Dermochelys coriacea) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense.

Endocrine responses to diverse stressors of capture, entanglement and stranding in leatherback turtles (Dermochelys coriacea)

“…All 17 of the intentionally captured leatherbacks were judged by the attending veterinarian to be in good health. Details of the general health status, physiological status, and post-release monitoring of most of these turtles have been reported previously ( Innis et al , 2010 , 2014 ; Dodge et al , 2014 , 2015 ) and support the categorization of the intentionally captured turtles as ‘healthy’.…”

“…Seventeen leatherback turtles were captured off the coast of Massachusetts in 2007, 2008, 2009 and 2012 as part of an ecology and health assessment study, details of which have been described previously ( Innis et al , 2010 , 2014 ; Dodge et al , 2011 , 2014 , 2015 ). The location, sex, date of sampling, body temperature, ambient water temperature (where available), curved carapace length and venipuncture site are presented for all turtles in Table 1 .…”

“…Entangled and entrapped turtles were freed from the fishing gear, evaluated and released (for details, see Innis et al , 2010 ; Dodge et al , 2014 , 2015 ). Stranded turtles were either hospitalized for attempted rehabilitation ( n = 3) or humanely euthanized if found to be moribund ( n = 3).…”

“…For example, studies using intentional capture (e.g. to attach tags for satellite telemetry) have provided substantial insight into the natural history, ecology and health of the species ( James and Mrosovsky, 2004 ; James et al , 2005 , 2007 ; Doyle et al , 2008 ; Innis et al , 2010 ; Benson et al , 2011 ; Dodge et al , 2011 , 2014 , 2015 ; Harris et al , 2011 ), but potential impacts of capture on stress physiology have rarely been assessed ( Innis et al , 2014 ).…”

Spatial Ecology of Sub-Adult Green Turtles in Coastal Waters of the Turks and Caicos Islands: Implications for Conservation Management

“…Marine turtles are a taxon for which satellite tracking has been transformational in unraveling complicated life histories (Godley et al, 2008). For adult turtles, migration patterns have become well elaborated (Fossette et al, 2014;Hays et al, 2014;Dodge et al, 2015) also highlighting important within and between population differences in movement patterns. In line with many aspects of marine turtle ecological studies (Wildermann et al, 2018) juvenile movements have been relatively understudied (Godley et al, 2008;Jeffers and Godley, 2016).…”