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.

The distribution and seasonal patterns of the North Atlantic right whale, Eubalaena glacialis, inform management decisions that mitigate anthropogenic threats. Based on data from visual surveys, much of the population migrates between winter calving grounds in coastal waters adjacent to the southeast USA and summer feeding and nursery grounds adjacent to the northeast USA. However, little is known about right whale occurrence along the mid-Atlantic US migratory corridor. A better understanding of right whale occurrence in this region is needed prior to offshore wind energy development activities, which may increase mortality risks and chronic impacts on the population. We conducted an 11 mo passive acoustic survey along coastal North Carolina and Georgia near several wind energy areas to document the acoustic occurrence of right whales in the southern region of the mid-Atlantic US coast. Right whales were acoustically detected across all seasons, with peak seasonal presence occurring during autumn in the Georgia site and during winter in the North Carolina site. A secondary peak in presence also occurred during June and July in the Georgia site, when right whales were not expected to be in the area. Given the nearly year-round presence of right whales in the survey areas, these results may warrant an evaluation of current management protocols in order to provide adequate protection to the population in the face of offshore energy development activities.

1. The New York Bight is an extremely busy maritime region, with extensive shipping traffic and commercial fishing activity. It is part of the migratory ranges of a number of cetacean species, and includes threats from ship strikes, noise exposure, and line entanglements. Previous cetacean surveys of the Bight offer limited information on cetacean occurrence and distribution in the region, having been restricted to visual sightings with limited temporal coverage. A passiveacoustic monitoring survey was conducted over a 258-day period to broaden understanding of the seasonal occurrences of blue (Balaenoptera musculus), fin (Balaenoptera physalus), and North Atlantic right (Eubalaena glacialis) whales during late summer, autumn, winter, and early spring. Stationary acoustic recorders were positioned near the entrance to New York Harbour and as a linear transect extending from Long Island to the continental shelf edge.3. Blue, fin, and right whales were detected on 11%, 100%, and 16% of the survey days, respectively. Blue whales were detected offshore during January, February, and March. Fin whales were detected offshore every day, and less often near-shore. Right whales occurred sporadically during every month, but were most often detected at near-shore recorders between late February and mid-May.4. Based on the acoustic data alone, it is unclear exactly how these species are using this habitat, although it is clear that they occur in the area longer than was previously thought. Thus, management practices should incorporate this extended seasonal presence to mitigate any effects on the whales from shipping and fishing activities.

No abstract

No abstract

The North Atlantic right whale (Eubalaena glacialis) is one of the world's most highly endangered baleen whales, with approximately 400–450 individuals remaining. Massachusetts Bay (MB) and Cape Cod Bay (CCB) together comprise one of seven areas in the Gulf of Maine where right whales seasonally congregate. Here, we report on acoustically detected presence of right whales in MB over a nearly 6 year period, July 2007–April 2013, a time of both rapid ocean warming throughout the Gulf of Maine and apparent changes in right whale migratory dynamics. We applied an automated detection algorithm to assess hourly presence of right whale “up‐calls” in recordings from a 19‐channel acoustic array covering approximately 4,000 km2 in MB. Over the survey, up‐calls were detected in 95% of 8 day periods. In each year, as expected, we observed a “peak season” of elevated up‐call detections in late winter and early spring corresponding to the season when right whales congregate to feed in CCB. However, we also saw an increase in right whale occurrence during time periods thought to be part of the “off‐season.” With the exception of 2009–2010, when acoustic presence was unusually low, the mean percent of hours in which up‐calls were detected increased every year, both during the peak season (from 38% in 2008 to 70% in 2012), and during the summer–fall season (from 2% in 2007 to 13% in 2012). Over the entire study, the peak season start date varied between 17 January and 26 February. Changes in right whale phenology in MB likely reflect broadscale changes in habitat use in other areas within the species range. This study demonstrates the value of continuous long‐term survey datasets to detect and quantify shifts in cetacean habitat use as environmental conditions change and the long‐term continued survival of right whales remains uncertain.

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.

Blue whales Balaenoptera musculus in the Indian Ocean (IO) are currently thought to represent 2 or 3 subspecies (B. m. intermedia, B. m. brevicauda, B. m. indica), and believed to be structured into 4 populations, each with a diagnostic song-type. Here we describe a previously unreported song-type that implies the probable existence of a population that has been undetected or conflated with another population. The novel song-type was recorded off Oman in the northern IO/Arabian Sea, off the western Chagos Archipelago in the equatorial central IO, and off Madagascar in the southwestern IO. As this is the only blue whale song that has been identified in the western Arabian Sea, we label it the 'Northwest Indian Ocean' song-type to distinguish it from other regional song-types. Spatiotemporal variation suggested a distribution west of 70°E, with potential affinity for the northern IO/Arabian Sea, and only minor presence in the southwestern IO. Timing of presence off Oman suggested that intensive illegal Soviet whaling that took 1294 blue whales in the 1960s likely targeted this population, as opposed to the more widely distributed 'Sri Lanka' acoustic population as previously assumed. Based upon geographic distribution and potential aseasonal reproduction found in the Soviet catch data, we suggest that if there is a northern IO subspecies (B. m. indica), it is likely this population. Moreover, the potentially restricted range, intensive historic whaling, and the fact that the song-type has been previously undetected, suggests a small population that is in critical need of status assessment and conservation action.