A modified hoop net (Fuhrman Diversified, Seabrook, Texas, U.S.A) was used to capture a total of 20 adults, which were anaesthetized with isoflurane gas delivered via a portable gas vaporizer (Stinger, Advanced Anaesthesia Specialists, Gladesville, NSW, Australia) during the process. A quick-setting, two-part epoxy resin (Accumix 268; Huntsman Advanced Materials) was used to attach a dive behaviour logger (Mk10; Wildlife Computers Ltd.) and a FastLoc GPS data logger (Sirtrack Ltd.) to the dorsal midline pelage just posterior to the scapula. Samples from the dive behaviour loggers were taken every 1- or 5-seconds intervals, while the GPS position was sampled at 10 minutes intervals when seals were at the surface. In the trailing edge of each fore flipper, a plastic tag (Super Tags, Dalton, Woolgoolga, Australia) was inserted, and, in the pelage posterior to the dive behaviour and GPS loggers, a very high frequency (VHF) transmitter (Sirtrack Ltd.) was glued to facilitate relocation for recapture.