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

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 focused on nesting beaches and elaborating migratory corridors, these species spend the vast majority of their lifecycle 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 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;. 623 turtles were fitted with flipper tags, with 69 subsequently recaptured, five of which in international waters. Sixteen individual turtles of between 63 and 81 cm curved carapace length were satellite tracked for a mean 226 days (range: 38-496). Data revealed extended periods of occupancy in the shallow coastal waters within a RAMSAR protected area. Satellite tracking and flipper tagging showed wide-ranging movements, with flipper tag recaptures occurring in waters off Nicaragua (n = 4), and Venezuela (n = 1). Also, four of 16 satellite tracked turtles exhibiting directed movements away (displaced >450 km) from TCI waters traveling through nine geo-political zones within the Caribbean-Atlantic basin, as well as on the High Seas. One turtle traveled 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.

Fine‐scale movement and habitat use of juvenile, subadult, and adult green turtles (Chelonia mydas) in a foraging ground at Ningaloo Reef, Australia

“…The average size of the 50% and 95% KUDs in juvenile, subadult, and adult green turtles at Ningaloo were less than 0.66 and 5.0 km 2 , respectively, and are consistent with published research on juveniles (Makowski et al, 2006;Fuentes et al, 2019;Wildermann et al, 2019;Chambault et al, 2020;Griffin et al, 2020), subadults (Chambault et al, 2018;Doherty et al, 2020;Siegwalt et al, 2020), and adults (Whiting & Miller, 1998;Gredzens et al, 2014;Christiansen et al, 2017;Shimada et al, 2020). These studies have estimated 50% abundant macroalgae and seagrass (Vanderklift et al, 2020).…”

High accuracy tracking reveals how small conservation areas can protect marine megafauna

“…So the reasons why some individuals remained close to the tagging site while other travelled afar remains enigmatic. Previous work has shown that immature turtles may sometimes relocate from one shallow, benthic foraging site to another (e.g., Mortimer et al 2010, Shimada et al 2014, Doherty et al 2020, so the occasional relocations we observed, although unexplained, may be a general trait of immature turtles. We have collected tissue samples from turtles foraging on Diego Garcia and future genetic analysis may reveal their natal sites which may explain some of the individual differences in movement.…”

“…2014, Doherty et al. 2020), so the occasional relocations we observed, although unexplained, may be a general trait of immature turtles. We have collected tissue samples from turtles foraging on Diego Garcia and future genetic analysis may reveal their natal sites which may explain some of the individual differences in movement.…”

Satellite Tracking of Post-nesting Green Sea Turtles (Chelonia mydas) From Ras Baridi, Red Sea

“…Studies conducted elsewhere have shown positive benefit for sea turtles in marine protected areas (Scott et al, 2012;Hart et al, 2013;Revuelta et al, 2015;Doherty et al, 2020). For green turtles, this results from the protection of seagrass and algal habitats over large areas along with the management of fishing and other anthropogenic activities to benefit the marine fauna, including marine turtles (PERSGA, 2007;Read et al, 2014).…”