@article {58004, title = {Seasonal variation in Arctic marine mammal acoustic detection in the northern Bering Sea}, journal = {Marine Mammal Science}, year = {2019}, month = {Dec-12-2020}, abstract = {

Declines in Arctic sea ice cover are influencing the distribution of protected endemic marine mammals, many of which are important for local Indigenous Peoples, and increasing the presence of potentially disruptive industrial activities. Due to increasing conservation concerns, we conducted the first year-round acoustic monitoring of waters off Gambell and Savoonga (St. Lawrence Island, Alaska), and in the Bering Strait to quantify vocalizing presence of bowhead whales, belugas, walruses, bearded seals, and ribbon seals. Bottom-mounted archival acoustic recorders collected data for up to 10\ months per deployment between 2012 and 2016. Spectrograms were analyzed for species-typical vocalizations, and daily detection rates and presence/absence were calculated. Generalized additive models were used to model call presence as a function of time-of-year, sea surface temperature, and sea ice concentration. We identified seasonality in call presence for all species, corroborating previous acoustic and distribution studies, and identified finer-scale spatiotemporal distribution via occurrence of call presence between different monitoring sites. Time-of-year was the strongest significant effect on call presence for all species. These data provide important information on Arctic endemic species\&$\#$39; spatiotemporal distributions in biologically and culturally important areas within a rapidly changing Arctic region.

}, issn = {0824-0469}, doi = {10.1111/mms.12658}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/mms.12658}, author = {Chou, Emily and Antunes, Ricardo and Sardelis, Stephanie and Stafford, Kathleen M. and West, Leigh and Spagnoli, Christopher and Southall, Brandon L. and Robards, Martin and Howard C. Rosenbaum} } @article {53284, title = {Double-difference tracking of migrating Bowhead Whales using autonomous vector sensors in the Beaufort Sea}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1695 - 1696}, abstract = {

Passive acoustic monitoring has become a standard method for detecting bowhead whale (Balaena mysticetus) activity in Arctic waters. Between 2007 and 2014, over 40 autonomous vector sensors, known as DASARs, were deployed in the Beaufort Sea during the bowhead whale migration season. Individual DASARs can estimate azimuth, allowing calls to be localized by triangulation using multiple DASARs. However, these bearings are subject to calibration biases, and individual sensors were not precisely time-synchronized, making relative time-of-arrival information unreliable for standard localization purposes. Double-difference methods have previously been applied in seismology to obtain high-precision relative positions of earthquakes by measuring changes in relative travel-times between multiple events over widely distributed seismic sensors. This same concept has also been used to track fin whales on a seafloor seismic network. Here, the double-difference method is applied to previously localized bowhead whale calls in order to improve their relative positions. The approach uses changes in both relative call travel-times and bearings, detected at multiple DASARs, to determine high-precision relative locations of these calls despite the presence of systemic timing and bearing errors in the measurements. The resulting positions may allow tracking of individual whales, which would provide insight into the function of these calls.

}, issn = {0001-4966}, doi = {10.1121/1.5067536}, url = {http://asa.scitation.org/doi/10.1121/1.5067536}, author = {Tenorio-Hall{\'e}, Ludovic and Thode, Aaron and Alexander S. Conrad and Blackwell, Susanna B. and Kim, Katherine H.} } @article {53280, title = {Acoustic response of a migrating bowhead whale population to open-ocean ambient noise levels}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1696 - 1696}, abstract = {

Automated and manual acoustic localizations of migrating bowhead whale calls in the Beaufort Sea were used to examine their acoustic response to changes in wind-driven, continuous, ambient noise levels. At low noise levels, the population\’s source levels and calling rates increased with increasing noise level, with the source level distribution adjusting to maintain a consistent functional detection range, estimated to be between 20 and 60 km. However, once noise levels exceeded the 75thpercentile of their long-term distribution, source level increases failed to keep pace with further increases in noise level, thereby reducing the population\’s detection range and associated communication space. Call production rates, on the other hand, continued to increase even up to the highest noise levels. Migrating bowhead whales thus attempted to maintain long-range call detectability by adjusting their source level and calling rate. Beyond a certain noise level, whales cannot increase their source levels, but do continue to increase their calling rate. The results provide context for interpreting the effects of industrial noise on bowhead whale acoustic behavior; for example, distant airgun signals stimulate an increase in mean call production rate equivalent to a 26 dB increase in natural ambient noise levels. [Work sponsored by NPRB.]

}, issn = {0001-4966}, doi = {10.1121/1.5067538}, url = {http://asa.scitation.org/doi/10.1121/1.5067538}, author = {Thode, Aaron and Blackwell, Susanna B. and Kim, Katherine H. and Alexander S. Conrad} }