Revealing migratory behaviour of South African leatherback turtles

Nathan J. Robinson, The Leatherback Trust

Previous studies have shown that the world’s largest reptile – the leatherback turtle Dermochelys coriacea – conducts flexible foraging migrations that can cover thousands of kilometres between nesting
sites and distant foraging areas. The vast distances that may be travelled by migrating leatherback turtles have greatly complicated conservation efforts for this species worldwide. However, we demonstrate,
using a combination of satellite telemetry and stable isotope analysis, that approximately half of the nesting leatherbacks from an important rookery in South Africa do not migrate to distant foraging
areas, but rather, forage in the coastal waters of the nearby Mozambique Channel. Moreover, this coastal cohort appears to remain resident year-round in shallow waters (<50 m depth) in a relatively fixed
area. Stable isotope analyses further indicate that the Mozambique Channel also hosts large numbers of loggerhead turtles Caretta caretta. The rare presence of a resident coastal aggregation of leatherback
turtles not only presents a unique opportunity for conservation, but alongside the presence of loggerhead turtles and other endangered marine megafauna in the Mozambique Channel, highlights the
importance of this area as a marine biodiversity hotspot.

The data were collected from nesting leatherback turtles (Dermochelys coriacea) that tracked via satellite transmitters from the iSimangaliso Wetland Park, South Africa.

All the individuals were adult female leatherback turtles that were tagged while on their nesting beaches.

As these data have already been processed in a State-Space Model there is only one location per day and time is not available.

Overview

This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
All attributes are included in the downloadable file (CSV or ESRI File Geodatabase) for "Complete Set of Dataset".

Attributes in dataset

Attribute (table column)	Description
oid	Unique ID number (generated by OBIS-SEAMAP)
tag_id	Tag/Turtle ID
obs_datetime	Date of the location
lon	Longitude in decimal degrees
lat	Latitude in decimal degrees
age	Age
sex	Sex
sp_obs	Species name
sp_tsn	Taxonomic Serial Number added by OBIS-SEAMAP
obs_count	Number of animal. Always 1
geom	Geometry field added by OBIS-SEAMAP