Fur seal research. Antarctic fur seal (Arctocephalus gazella) with a satellite tag for biological research. The tag contains radio and satellite transmitters, and a time-depth recorder (TDR). The TDR provides data on the duration and depth of the seal's hunting dives. The satellite transmitter allows it to be followed as it moves around, and the radio transmitter allows the seal to be located by the researchers. Such research provides information about the behaviour of the seal, and aids understanding of how it interacts with its environment. Photographed at the Bird Island Research Station, South Georgia Islands.