Several marine autonomous recording units (MARUs) were deployed in northeastern Gulf of Mexico from 2010–2012 to study the acoustic ecology of Bryde's whales (Balaenoptera edeni) following the Deepwater Horizon oil spill. However, the acoustic repertoire of this sub-population is poorly documented, presently limiting the efficacy of acoustic monitoring applications. Numerous stereotyped, low-frequency signals from a putative biological sound source were found throughout the recordings. Sounds fell into three categories distinguished by spectral and temporal properties. Multiple calls overlapped temporally on individual MARUs, suggesting that multiple sources produced these sounds. The basic features are similar to those from other mysticetes, but they differ from any previously published sounds. Since Bryde's whales are the most common mysticete in the Gulf and have previously been observed within the recording area on multiple occasions, it is likely that Bryde's whales are the most probable source of these sounds. These results potentially identify a suite of previously undocumented calls from Bryde's whales, which could facilitate future passive acoustic monitoring efforts to better understand the population dynamics and status of this sub-population.
We would like to thank D. Doxey, C. Tessaglia-Hymes, and D. Salisbury for assistance with deployment, recovery, and synchronization; C. Diamond, B. Estabrook, K. Hodge, A. Izzi, M. Loman, C. Pelkie, A. Rahaman, E. Rowland, D. Salisbury, and A. Warde for their assistance with data analysis. Special thanks to STGC McKinney and STG1 Schmeck of Fleet Anti-Submarine Warfare Training Center in Point Loma, CA, George “Chuck” Gagnon (Ret. LCDR, USN), and K. Stafford for their perspectives and evaluation of sounds of interest. Funding was provided through a contract from BP Production and Exploration, Inc., with scientific input from the National Oceanic and Atmospheric Administration's Southeast Fisheries Science Center and Office of Response and Restoration; BP had no role in the study design or execution and no influence over the reported results. The statements, findings, and conclusions are those of the authors, and do not necessarily reflect the views of BP, or any State or Federal Natural Resource Trustee.
I. INTRODUCTION II. METHODS A. Acoustic recordings B. Acoustic analysis C. Acoustic locating and tracking III. RESULTS A. Signal descriptions B. Acoustic locations and tracks IV. DISCUSSION