Abstract
Marine turtles are of conservation concern throughout their range, with past population declines largely due to exploitation through both legal and illegal take, and incidental capture in fisheries. Whilst much research effort has been focussed on nesting beaches and elaborating migratory corridors, these species spend the vast majority of their life-cycle in foraging grounds, which are, in some species, quite discrete. To understand and manage these populations, empirical data are needed on distribution, space-use, and habitats in order to best inform design of protective measures. Here we describe space-use, occupancy, and wide-ranging movements derived from conventional flipper tagging and satellite tracking of sub-adult green turtles (Chelonia mydas) within the coastal waters of the Turks and Caicos Islands (TCI; 2011-2017). Sixteen individual turtles of between 63 and 81 cm curved carapace length (CCL) were satellite tracked for a mean 226 days (range: 38-496). Analyses of both satellite tracking and conventional flipper tagging data revealed extended periods of occupancy in the shallow coastal waters within a RAMSAR protected area that includes seagrass beds and algae-rich tidal creeks. Satellite tracking also revealed wide-ranging movements, with four of 16 turtles exhibiting directed movements away (displaced >450 km) from TCI waters travelling through nine geo-political zones within the Caribbean-Atlantic basin, as well as on the High Seas. One turtle travelled to the Central American coast before settling on inshore habitat in Colombia’s waters for 162 days before transmission ceased, indicating ontogenetic dispersal to a distant foraging habitat. These data highlight connectivity throughout the region, displaying key linkages between countries that have previously only been linked by genetic evidence. This study also provides evidence of the importance of the Turks and Caicos Islands marine protected area network and importance of effective management of the sea turtle fishery for regional green turtle populations.
Highlights
Satellite telemetry has transformed the study of many marine vertebrate species, there are challenges with early life stages and animals which rarely surface (Hazen et al, 2012; Hussey et al, 2015; Hays et al, 2016)
All satellite tracked turtles were caught within the RAMSAR site between 2011 and 2017 (Figures 1A,B) and deemed to be sub-adult (
One other sub-adult green turtle was satellite tagged during this study in April 2017 (89 cm CCL), but was subsequently illegally caught by fishers within the RAMSAR site eight days after release
Summary
Satellite telemetry has transformed the study of many marine vertebrate species, there are challenges with early life stages and animals which rarely surface (Hazen et al, 2012; Hussey et al, 2015; Hays et al, 2016). With the advancement of bio-logging leading to smaller tags, longer battery duration, and increased location accuracy (Hays et al, 2016), our ability to gather insight into complex life history characteristics and migratory life cycles of many marine vertebrates has improved – essential information to inform conservation efforts (Greene et al, 2009; Hammerschlag et al, 2011; Hazen et al, 2012; Hays et al, 2019). Studies have begun to give important insights into the movements and dispersal of juveniles (Hart and Fujisaki, 2010; Mansfield et al, 2014; Putman and Mansfield, 2015; Chambault et al, 2018)
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