GMR continues to undertake a long-term acoustic monitoring program that GMR researchers based at Curtin University commenced.

Most people would have heard about the “songs” of various whale species. Humpbacks are well known for their songs, which evolve over time. Many species have similar capability to make sounds to communicate, attract mates, warn of danger and for echolocation (a sort of biosonar that for example dolphins use to navigate their environment)).

Whale song is made up of a mixture of sounds. For some species the sounds have been described as sounding like moans, snores, chirps and cries. They are all below 4 kHz in frequency. Blue and fin whale songs are so low in frequency that parts of them are inaudible to humans. Humpback whales produce the most complex song of the lot. It consists of repeated phrases arranged in themes in a hierarchical structure, and can last from approximately 35 minutes. Individual whales have been found to sing for up to 22 hours, repeating the song over and over again.

Passive Acoustic Monitoring (PAM) research is undertaken by placing an underwater microphone (called a hydrophone) in the water and recording the sounds in a data logger. These data loggers can remain in place for very long periods, and they detect sounds of whales and other species, as well as boats and ships. Monitoring whales in this way provides information about sounds whales make when the whale is underwater, above water (e.g. breaching) and at night. Other methods of monitoring rely on visual sightings.

The sounds recorded from whales have been extensively analysed in the past and many species can be identified from these sounds alone. Here are some examples of non-song sounds from blue whales from a paper by

Recalde-Salas, A., Erbe, C., Salgado Kent, C.P., and Parsons, M. (2020) Non-song vocalizations of humpback whales in Western Australia. Frontiers in Marine Science. DOI: 10.3389/fmars.2020.00141.

example of humpback acoustic

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