This one sat around for a while waiting for me to write about it, but it’s pretty timeless, so here goes!  One of the leaders in fish bioacoustics, Rodney Rountree, wrote a great overview piece in the Nov/Dec issue of Marine Technology Review on the groundbreaking work being done in fish biology using Passive Acoustic recording systems.  The article does a wonderful job of introducing the various approaches being taken to recording freshwater and oceanic fish.  The most exciting aspect of this work is that until quite recently, very few biologists even CONSIDERED fish as vocal or acoustic creatures (the emphasis was on chemical/smell and mechanical/tactile sensitivity).  As Rountree notes, “currently most biological sounds recorded in marine and aquatic habitats are unknown due to the lack of study and a lack of comprehensive sound catalogues.”  It’s agua incognita!  

To enter this fascinating new acoustic world, Rountree has compiled three distinct yet complementary overviews:

• The article in MTR is on Page 40 of this pdf version of the issue. 
• You can download his 42-page “e-book” nominally written for children, but in fact a wonderful layperson overview of the history and current discoveries in fish acoustics; it’s full of links to websites. 
• And, his academic website FishEcology.org has a page that is full of fish sounds, including a slew of unidentified sounds.