Centre for Marine Science and Technology BLUE WHALE CALLING IN THE ROTTNEST TRENCH - 2000, WESTERN AUSTRALIA

........................................................................................................................................... 2 Acknowledgments ........................................................................................................................... 2 1) Introduction................................................................................................................................. 4 2) Methods....................................................................................................................................... 6 3) Results ....................................................................................................................................... 10 3.1) 'Blue' whale calls................................................................................................................ 10 3.1.1) Call / Component structure ......................................................................................... 10 3.1.2) Received component levels ......................................................................................... 15 3.1.3) Type II received levels ................................................................................................ 16 3.2) Blue whale call propagation general and bluey logger site ............................................. 17 3.3) Blue whale source levels.................................................................................................... 22 3.4) Transmission of blue whale calls to bluey site................................................................... 26 3.5) Transmission of blue whale calls to drifting site ............................................................... 30 3.6) Other signals recorded........................................................................................................ 32 3.6.1) 20 Hz 'clicking' ............................................................................................................ 32 3.6.2) Air-gun signals ............................................................................................................ 33 3.6.3) Twenty second 125 Hz signal..................................................................................... 33 3.6.4) Four second 'chirps'..................................................................................................... 34 3.6.5) Dolphin signals............................................................................................................ 34 3.7) Blue whale call search techniques...................................................................................... 34 3.8) Blue whale calling through time:....................................................................................... 38 4) Discussion................................................................................................................................. 51 5) References ................................................................................................................................. 54