Australian waters are home to a number of vocal species of fish. Cataloguing the acoustic characteristics and temporal patterns of choruses and their locations can provide significant information for long-term monitoring of vocal fishes and their ecosystems. In coastal waters off Port Hedland, Western Australia, two seafloor positioned sea-noise loggers, located 21.5 km apart in 8 and 18 m of water, recorded for an 18-month period. Numerous sound sources were detected, including mooring and vessel noise, humpback whale song and a large variety of fish signal types. Seven fish choruses were identified, occurring predominantly between late spring and early autumn (wet season) and displaying energy from 50 Hz to >4 kHz. Many of these choruses exhibited acoustic characteristics similar to choruses previously reported elsewhere, for some of which the source species or families have been identified. Distinct diurnal patterns in the choruses were observed, associated with sunrise or sunset and in some cases, both. While choruses were predominantly recorded on different days, there were at total of 80 days when more than one chorus was present at the same site. Some pairs of choruses present on the same day exhibited various combinations of temporal and frequency partitioning, while others displayed predominant overlap in both spaces.
peterpanisavampire on April 8th, 2017 at 12:33 UTC »
Ever since sonar was invented, the Navies of the world have been listening to some of the weirdest sounds on earth, but it is often years or decades before those sounds are identified, since sonarmen are not biologists. In the US Navy tech manuals, there is a sound described, a low frequency groan called "jezemonster", that has been known of from the very beginning of sonar. Even now, there is debate on what animal is making that noise, though most agree that it's some type of whale. Unfortunately, most navies don't publish recordings of these sounds due to the sensitive nature of the submarines' missions. The recording provided by OP is similar to sounds I have heard in many parts of the world, and is part of something we called the diurnal effect; at dawn and dusk each day, the background noise would intensify dramatically, making it much more difficult to detect other ships. I find it very interesting that only now is official evidence being published for this.
necius on April 8th, 2017 at 11:01 UTC »
I recently finished reading the book What A Fish Knows by Jonathan Balcombe ([here's his AMA](https://www.reddit.com/r/IAmA/comments/5n5jxs/im_jonathan_balcombe_ethologist_and_author_of/)). The complexity of fish cognition and social lives is already astounding, and we've barely studied any of it.
Codexlibero on April 8th, 2017 at 00:43 UTC »
[Recording](https://www.youtube.com/watch?v=6HhwFa1cDbc)