Ecosystem Scale Acoustic Sensing Reveals Humpback Whale Behavior Synchronous with Herring Spawning Processes and Re-Evaluation Finds No Effect of Sonar on Citation

We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, vocalizing whales could be instantaneously detected and localized over most of the Gulf of Maine ecosystem in a roughly 400-km diameter area by introducing array gain, of 18 dB, orders of magnitude higher than previously available in acoustic whale sensing. With humpback-whale vocalizations consistently recorded at roughly 2000/day, we show that vocalizing humpbacks (i) were overwhelmingly distributed along the northern flank of Georges Bank, coinciding with the peak spawning time and location of Atlantic herring, and (ii) their overall vocalization behavior was strongly diurnal, synchronous with the formation of large nocturnal herring shoals, with a call rate roughly ten-times higher at night than during the day. Humpback-whale vocalizations were comprised of (1) highly diurnal non-song calls, suited to hunting and feeding behavior, and (2) songs, which had constant occurrence rate over a diurnal cycle, invariant to diurnal herring shoaling. Before and during OAWRS survey transmissions: (a) no vocalizing whales were found at Stellwagen Bank, which had negligible herring populations, and (b) a constant humpback-whale song occurrence rate indicates the transmissions had no effect on humpback song. These measurements contradict the conclusions of Risch et al. Our analysis indicates that (a) the song occurrence variation reported in Risch et al. is consistent with natural causes other than sonar, (b) the reducing change in song reported in Risch et al. occurred days before the sonar survey began, and (c) the Risch et al. method lacks the statistical significance to draw the conclusions of Risch et al. because it has a 98–100% false-positive rate and lacks any true-positive confirmation. Citation: Gong Z, Jain AD, Tran D, Yi DH, Wu F, et al. (2014) Ecosystem Scale Acoustic Sensing Reveals Humpback Whale Behavior Synchronous with Herring Spawning Processes and Re-Evaluation Finds No Effect of Sonar on Humpback Song Occurrence in the Gulf of Maine in Fall 2006. PLoS ONE 9(10): e104733. doi:10. 1371/journal.pone.0104733 Editor: Z. Daniel Deng, Pacific Northwest National Laboratory, United States of America Received December 19, 2012; Accepted June 23, 2014; Published October 7, 2014 Copyright: 2014 Gong et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was supported by the National Oceanographic Partnership Program, the Census of Marine Life, the Office of Naval Research, the Alfred P. Sloan Foundation, the National Science Foundation, the Presidential Early Career Award for Scientists and Engineers, Northeastern University, and Massachusetts Institute of Technology. The authors thank David Reed for providing technical assistance. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Two of the co-authors of this manuscript are inventors of the patent US20060280030 (‘Continuous, continental shelf-scale monitoring of fish populations and behavior’) which is owned by MIT and was discovered under US Government Research Sponsorship, giving the US Government certain rights with regard to this patent. This patent involves ocean acoustic waveguide remote sensing of fish populations. The authors also confirm that this does not alter their adherence to the PLOS ONE policies on sharing data and materials. * Email: [email protected] ¤ Current address: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America