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Autonomous passive acoustic recorders were deployed to record sounds of bowhead whales (Balaena mysticetus) in the southeast Beaufort Sea for periods of 30-55 days during the late summer, open-water seasons of 2008-2010. Recordings were made in three areas licensed for hydrocarbon exploration, spanning the continental slope and adjacent outer shelf, and in a shallow inner-shelf area where bowheads have been observed congregating to feed in recent decades. Bowhead sounds were counted in samples comprising 10% of each recorded hour. In mid-August and September in all 3 years, the rate of bowhead calling at outer shelf sites exceeded that at adjacent continental slope sites by one to two orders of magnitude. Higher rates of calling occurred on the slope in late July and early August than at later dates. Calling rates varied by an order of magnitude between years in the one area that was monitored in different years. The highest rates of calling occurred on the inner shelf, offshore of the northern Tuktoyaktuk Peninsula. These trends are consistent with patterns of habitat use previously reported from aerial surveys in this and nearby areas of the Beaufort Sea and with the results of satellite tagging studies. [ABSTRACT FROM AUTHOR]

The article presents a study on the acoustic responses of blue whales or Balaenoprera musculus to sounds from seismic surveys, particularly the calling behavior of blue whales during seismic operations in the St. Lawrence Estuary (SLE), Canada where a low-medium power technology or sparker was deployed. Data collected showed the noise from seismic sparker operations induced more call production from the blue whales. Other vocal adjustments observed include shifting call frequency, increased call amplitude and ceasing to call.

This paper considers the problem of detection of contact calls produced by the critically endangered North Atlantic right whale, Eubalaena glacialis. To reduce computational time, the class of acceptable detectors is constrained by the detectors implemented as a bank of two-dimensional linear FIR filters and using the data spectrogram as the input. The closed form representations for the detectors are derived and the detection performance is compared with that of the generalized likelihood ratio test (GLRT) detector. The test results demonstrate that in the presence of impulsive noise, the spectrogram-based detector using the French hat wavelet as the filter kernel outperforms the GLRT detector and decreases computational time by a factor of 6. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of passive acoustic detection of contact calls produced by the highly endangered North Atlantic right whale Eubalaena glacialis. The proposed solution is based on using a generalized likelihood ratio test detector of polynomial-phase signals with unknown amplitude and polynomial coefficients observed in the presence of locally stationary Gaussian noise. The closed form representation for a minimal sufficient statistic is derived and a realizable detection scheme is developed. The receiver operation characteristic curves are calculated using empirical data recordings containing known right whale calls. The curves demonstrate that the proposed detector provides superior detection performance as compared with other known detection techniques for northern right whale contact calls. [ABSTRACT FROM AUTHOR]

Humpback whale song lengths were measured from recordings made off the west coast of the island of Hawai'i in March 1998 in relation to acoustic broadcasts ("pings") from the U.S. Navy SURTASS Low Frequency Active sonar system. Generalized additive models were used to investigate the relationships between song length and time of year, time of day, and broadcast factors. There were significant seasonal and diurnal effects. The seasonal factor was associated with changes in the density of whales sighted near shore. The diurnal factor was associated with changes in surface social activity. Songs that ended within a few minutes of the most recent ping tended to be longer than songs sung during control periods. Many songs that were overlapped by pings, and songs that ended several minutes after the most recent ping, did not differ from songs sung in control periods. The longest songs were sung between 1 and 2 h after the last ping. Humpbacks responded to louder broadcasts with longer songs. The fraction of variation in song length that could be attributed to broadcast factors was low. Much of the variation in humpback song length remains unexplained. [ABSTRACT FROM AUTHOR]

Discusses the vocal activity of fin whales in the Ligurian Sea. Relative simplicity of fin whale sounds compared to most other baleen species; Most common fin whale sound referred to as 20-Hz pulse; Variability in the specific acoustic characteristics of pulses; Example spectogram showing portion of fin whale pulse sequence.

We recorded a series of 34 fin whale vocalizations using four calibrated hydrophones in a towed array. The whale's location was determined using arrival-time differences of each call at the hydrophones. The recordings showed evidence of interference between signals propagating along direct and surface-reflected paths (the "Lloyd Mirror"). We made preliminary estimates of source level (SL) using a spherical spreading model of transmission loss. We then applied a conservative correction for the effect of interference by subtracting the maximum possible signal enhancement from the preliminary SL estimate. These adjusted spherical spreading estimates had a median of 171. dB re 1 µPa at 1 m, with a range of 159-184 dB. These are the first SL estimates that explicitly attempt to correct for possible interference effects. We also propose a method that simultaneously estimates SL and source depth by fitting a Lloyd Mirror transmission loss curve to the measured received level, known receiver depth, and source-to-receiver range. Attempts to apply this method to the present data set yielded inconsistent results, probably because of the small number of hydrophones available. With more hydrophones in the interference field, this new method should produce reliable estimates of SL and depth of vocalizing whales. [ABSTRACT FROM AUTHOR]