[MARMAM] New publication on beaked whale strandings and naval sonar in Guam and the Mariana Islands

Anne Simonis anne.simonis at gmail.com
Wed Feb 19 09:11:43 PST 2020

Along with my co-authors, I'm proud to announce the publication of our
recent study entitled: Co-occurrence of beaked whale strandings and naval
sonar in the Mariana Islands,Western Pacific

The open-access article appears in the journal Proceedings B of the Royal
Society and is available at the following link:


Mid-frequency active sonar (MFAS), used for antisubmarine warfare (ASW),
has been associated with multiple beaked whale (BW) mass stranding events.
Multinational naval ASW exercises have used MFAS offshore of the Mariana
Archipelago semi-annually since 2006. We report BW and MFAS acoustic
activity near the islands of Saipan and Tinian from March 2010 to November
2014. Signals from Cuvier’s (Ziphius cavirostris) and Blainville’s beaked
whales (Mesoplodon densirostris), and a third unidentified BW species, were
detected throughout the recording period. Both recorders documented MFAS on
21 August 2011 before two Cuvier’s beaked whales stranded on 22–23 August
2011. We compared the history of known naval operations and BW strandings
from the Mariana Archipelago to consider potential threats to BW
populations. Eight BW stranding events between June 2006 and January 2019
each included one to three animals. Half of these strandings occurred
during or within 6 days after naval activities, and this co-occurrence is
highly significant. We highlight strandings of individual BWs can be
associated with ASW, and emphasize the value of ongoing passive acoustic
monitoring, especially for beaked whales that are difficult to visually
detect at sea. We strongly recommend more visual monitoring efforts, at sea
and along coastlines, for stranded cetaceans before, during and after naval

*Note Added In Proof:* After the manuscript was accepted for publication
additional information was made available to the authors by the US Navy.
Although the January 2019 beaked whale stranding occurred within the
publicly reported dates for Exercise Sea Dragon (14–26 January 2019), the
US Navy confirmed that there was no sonar usage associated with this
training exercise, or elsewhere within the Mariana Islands Training and
Testing area in the 6 days prior to the stranding. If this event is removed
from the statistical analysis, there is a 1% probability (see electronic
supplementary material, table S2) that three of eight beaked whale
strandings occurred within 6 days after MFAS operations by chance. As
discussed within the manuscript, the statistical analysis was limited to
assessing the overlap between beaked whale strandings and known MFAS events
(either via public reporting or through detection on passive acoustic
devices—see figure 3). The Navy is working with NOAA to make the broader
dataset, which is classified, available for further statistical analysis.

*Also of interest*: An additional beaked whale near stranding occurred on
the island of Rota in the Mariana Archipelago on November 21, 2019, which
is not included in this study. In the waters around Guam, a major
multinational naval ASW operation (Vanguard 2) began on Nov 20, 2019.
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