Developing an Underwater Sound Recorder: The Long and Short (Time) of It...

Passive acoustic recording of marine noise has advanced considerably over recent years. For a long time, a lack of widely available technology limited the acquisition of long-term acoustic data sets to a small number of large, cabled installations mostly restricted to military use. For other users, recordings were limited by the available technology to short snapshots of minutes to possibly days of data at a time. As technology has improved, passive acoustic monitoring has shown marine soundscapes are filled with biotic and abiotic sounds that occur on a range of often unpredictable timescales. Thus, snapshot recordings can lead to biased data. In 1999, the Centre for Marine Science and Technology, together with Australia's Defence Science and Technology Organisation, began developing remote underwater sound recorders to increase the duration and quality of recordings. As time passed, the sound recorders were developed significantly, have been deployed over 600 times at a variety of Australian and international locations and have identified a plethora of biological, geophysical and anthropogenic sound sources. This paper presents a brief history of the recorders' development and characteristics, some examples of the information they have provided and future direction for their next generation.