Flexible foraging: Post-nesting flatback turtles on the Australian continental shelf

Environmental predictors of foraging and transit behaviour in flatback turtles Natator depressus

“…As with other studies on this species (Whittock et al 2016), the movement behaviour and home range size of individual turtles was highly variable, with 3 turtles remaining around the breeding grounds post nesting, utilising small home range areas (12 to 15 km 2 ). In contrast, the other turtles made extensive movements to distant foraging grounds, with home ranges up to 30 times larger.…”

“…While this information is based on qualitative data, our results indicate deeper foraging depths compared to the Great Barrier Reef, with average water depths of 53 ± 26 m (74 ± 12 m for the 5 turtles with tracks over 60 d) and turtles located an average of 82 ± 60 km from shore (136 ± 35 km for the 5 turtles with tracks over 60 d). Slightly shallower mean water depths were reported for foraging flatback turtles tracked from nesting grounds farther south (Pilbara region of Western Australia) of 36.5 ± 22.5 m; however, there was a large range (up to 130 m), as was the case for foraging distance to shore (66 ± 62 km, range = 3 to 314 km) (Whittock et al 2016). Our model also found a strong association of turtle presence with clear water.…”

“…Of these variables, the strongest predictor of the presence of turtles in foraging mode was benthic geomorphology, notably terraces, deep holes and valleys. These habitats on the Sahul Shelf appear to enhance foraging habitat not just for flatback turtles from the Lacepede Islands rookery, but also for populations tagged at other rookeries (Barrow Island, Port Hedland, Mundabullangana) in Australia (Whittock et al 2016), and for other species such as olive ridley Lepidochelys olivacea (McMahon et al 2007, Whiting et al 2007) and loggerhead turtles Caretta caretta (Waayers et al 2015). Indeed, 20% (n = 90) of flatback turtles satellite tagged in Western Australia travelled to the Sahul Shelf, suggesting this area is an important foraging area for marine turtles throughout the year (Waayers et al 2015).…”

Multiple satellite tracking datasets inform green turtle conservation at a regional scale

“…Time spent was calculated using a 3 × 3 km square grid for inter-nesting and a 20 × 20 km square grid for migration and foraging. These grid cell sizes were selected based on the scale of the movements; very small (100 s of m to km) for inter-nesting and very large (100-1,000 s of km) for post-nesting and to be in line with grid cell sizes used for other turtle species distributions quantified in this region (Whittock et al, 2014(Whittock et al, , 2016.…”

Estimating long-term trends in abundance and survival for nesting flatback turtles in Kakadu National Park, Australia

“…The flatback turtle Natator depressus is the only turtle species endemic to Australia, with foraging grounds generally distributed throughout the Australian continental shelf, into Indonesian and Papua New Guinean waters (Limpus 2007, Whittock et al 2016. It has an extensive nesting distribution from the Pilbara region of Western Australia, along the (Pittard 2010), and there is evidence of restricted gene flow among some of the Arafura Sea stock, which may be more independent than genetic studies can currently determine (FitzSimmons & Limpus 2014).…”