Characterization of underwater soundscape variations pre- and post-ship shock trial underwater detonations

During Full Ship Shock Trials (FSSTs), a ship is subjected to a series of underwater detonations conducted at various distances to assess its ability to withstand shock waves that simulate near misses during combat. In the summer of 2021, the US Navy successfully conducted a FSST of the USS Gerald R. Ford, in the Atlantic Ocean off the coast of Jacksonville, FL. We collected passive acoustic recordings during each of the three underwater detonations, using an array of bottom-moored autonomous underwater recorders—Rockhoppers and SoundTraps—that were deployed at 15 vantage positions around the three sites. While the acoustic recordings of the underwater detonations were aimed at providing the Naval Sea Systems Command valuable data for updating their underwater acoustic propagation models, it also provided opportunistic data to assess possible impacts on prevailing biota. Our analyses of the recordings included an assessment of the recorded soundscape pre- and post-trial and a characterization of relative vocal activity by large faunal groups (baleen whales, delphinids, and fish). The results provide an insight into behavioral changes in response to the underwater detonations at different distances from the detonation sites as well as valuable information for improving impact mitigation considerations during future FSSTs.