David N. Wiley

'Megapclicks': acoustic click trains and buzzes produced during night-time foraging of humpback whales (Megaptera novaeangliae)

Humpback whales (Megaptera novaeangliae) exhibit a variety of foraging behaviours, but neither they nor any baleen whale are known to produce broadband clicks in association with feeding, as do many odontocetes. We recorded underwater behaviour of humpback whales in a northwest Atlantic feeding area using suction-cup attached, multi-sensor, acoustic tags (DTAGs). Here we describe the first recordings of click production associated with underwater lunges from baleen whales. Recordings of over 34 000 ‘megapclicks’ from two whales indicated relatively low received levels at the tag (between 143 and 154 dB re 1 μPa pp), most energy below 2 kHz, and interclick intervals often decreasing towards the end of click trains to form a buzz. All clicks were recorded during night-time hours. Sharp body rolls also occurred at the end of click bouts containing buzzes, suggesting feeding events. This acoustic behaviour seems to form part of a night-time feeding tactic for humpbacks and also expands the known acoustic repertoire of baleen whales in general.

Underwater components of humpback whale bubble-net feeding behaviour

Summary Humpback whales (Megaptera novaeangliae) employ a unique and complex foraging behaviour — bubble-netting — that involves expelling air underwater to form a vertical cylinder-ring of bubbles around prey. We used digital suction cup tags (DTAGs) that concurrently measure pitch, roll, heading, depth and sound (96 kHz sampling rate), to provide the first depiction of the underwater behaviours in which humpback whales engage during bubble-net feeding. Body mechanics and swim paths were analysed using custom visualization software that animates the underwater track of the whale and quantifies tag sensor values. Bubble production was identified aurally and through spectrographic analysis of tag audio records. We identified two classes of behaviour (upward-spiral; 6 animals, 118 events and double-loop; 3 animals, 182 events) that whales used to create bubble nets. Specifically, we show the actual swim path of the whales (e.g., number of revolutions, turning rate, depth interval of spiral), when and where in the process bubbles were expelled and the pattern of bubble expulsion used by the animals. Relative to other baleanopterids, bubble-netting humpbacks demonstrate increased manoeuvrability probably aided by a unique hydrodynamicly enhanced body form. We identified an approximately 20 m depth or depth interval limit to the use of bubble nets and suggest that this limit is due to the physics of bubble dispersal to which humpback whales have behaviourally adapted. All animals were feeding with at

Visualizing the underwater behavior of humpback whales

A new collaboration between visualization experts, engineers, and marine biologists has changed. For the first time, we can see and study the foraging behavior of humpback whales. Our studys primary objective was furthering the science of marine mammal ethology. We also had a second objective: field testing GeoZui4D, an innovative test-bench for investigate effective ways of navigating through time-varying geospatial data

Effectiveness of Voluntary Conservation Agreements: Case Study of Endangered Whales and Commercial Whale Watching

The use of voluntary approaches to achieve conservation goals is becoming increasingly popular. Nevertheless, few researchers have quantitatively evaluated their efficacy. In 1998 industry, government agencies, and nongovernmental organizations established a voluntary conservation program for whale watching in the northeast region of the United States, with the intent to avoid collisions with and harassment of endangered whales by commercial and recreational whale-watching vessels. One important aspect of the program was the establishment of 3 speed zones within specific distances of whales. We wanted to determine the level of compliance with this aspect of the program to gauge its efficacy and gain insights into the effectiveness of voluntary measures as a conservation tool. Inconspicuous observers accompanied 46 commercial whale-watching trips from 12 companies in 2003 (n= 35) and 2004 (n= 11). During each trip, vessel position and speed were collected at 5-second intervals with a GPS receiver. Binoculars with internal laser rangefinders and digital compasses were used to record range and bearing to sighted whales. We mapped whale locations with ArcGIS. We created speed-zone buffers around sighted whales and overlaid them with vessel-track and speed data to evaluate compliance. Speeds in excess of those recommended by the program were considered noncompliant. We judged the magnitude of noncompliance by comparing a vessels maximum speed within a zone to its maximum recorded trip speed. The level of noncompliance was high (mean 0.78; company range 0.74-0.88), some companies were more compliant than others (p= 0.02), noncompliance was significantly higher in zones farther from whales (p < 0.001), and operators approached the maximum speed capabilities of their vessel in all zones. The voluntary conservation program did not achieve the goal of substantially limiting vessel speed near whales. Our results support the need for conservation programs to have quantifiable metrics and frequent evaluation to ensure efficacy.

Dangerous dining: Surface foraging of North Atlantic right whales increases risk of vessel collisions

North Atlantic right whales are critically endangered and, despite international protection from whaling, significant numbers die from collisions with ships. Large groups of right whales migrate to the coastal waters of New England during the late winter and early spring to feed in an area with large numbers of vessels. North Atlantic right whales have the largest per capita record of vessel strikes of any large whale population in the world. Right whale feeding behaviour in Cape Cod Bay (CCB) probably contributes to risk of collisions with ships. In this study, feeding right whales tagged with archival suction cup tags spent the majority of their time just below the waters surface where they cannot be seen but are shallow enough to be vulnerable to ship strike. Habitat surveys show that large patches of right whale prey are common in the upper 5 m of the water column in CCB during spring. These results indicate that the typical spring-time foraging ecology of right whales may contribute to their high level of mortality from vessel collisions. The results of this study suggest that remote acoustic detection of prey aggregations may be a useful supplement to the management and conservation of right whales.

Evidence for ship noise impacts on humpback whale foraging behaviour

Noise from shipping activity in North Atlantic coastal waters has been steadily increasing and is an area of growing conservation concern, as it has the potential to disrupt the behaviour of marine organisms. This study examines the impacts of ship noise on bottom foraging humpback whales (Megaptera novaeangliae) in the western North Atlantic. Data were collected from 10 foraging whales using non-invasive archival tags that simultaneously recorded underwater movements and the acoustic environment at the whale. Using mixed models, we assess the effects of ship noise on seven parameters of their feeding behaviours. Independent variables included the presence or absence of ship noise and the received level of ship noise at the whale. We found significant effects on foraging, including slower descent rates and fewer side-roll feeding events per dive with increasing ship noise. During 5 of 18 ship passages, dives without side-rolls were observed. These findings indicate that humpback whales on Stellwagen Bank, an area with chronically elevated levels of shipping traffic, significantly change foraging activity when exposed to high levels of ship noise. This measureable reduction in within-dive foraging effort of individual whales could potentially lead to population-level impacts of shipping noise on baleen whale foraging success.

Underwater Tracking of Humpback Whales (Megaptera Novaeangliae) With High-Frequency Pingers and Acoustic Recording Tags

A long-baseline (LBL) acoustic system has been developed for the tracking of humpback whales (Megaptera novaeangliae) that have been tagged with digital acoustic recording devices (DTAGs), providing quantitative observations of submerged whale behavior during bubble net feeding. The system includes three high-frequency acoustic sources deployed from small boats that follow the whale after the animal has been tagged. Integrated global positioning systems (GPSs) provide positioning and synchronized operation of the sources. Time-encoded acoustic signals from the sources are recorded along with whale vocalizations and ambient noise on the whale tag. Time-of-flight measurements, as measured by the tag acoustic data, are converted to range from the whale to each source with a measured sound-speed profile. A nonlinear least squares solution is then solved for the whales position with a nominal positional fix rate of once per second. The system is demonstrated with data collected from a tagged animal in summer 2007. Dead-reckoned track generation methods commonly used in previous studies are shown to capture the qualitative nature of the whale track, albeit with poor absolute positional accuracy, and to distort the track when the whales movement is predominantly vertical. In contrast, the LBL data can provide quantitative measures of whale behavior. Transit speeds between bubble net feeding events for this case study are found to range from 0.7 to 1.9 m · s-1 (n = 8). The mean diameter of bubble net curtains are measured to range from 9.6 to 10.9 m. Whale speeds during bubble net rotations vary from 1.0 to 1.9 m · s-1 (n = 6).

Noise impacts on social sound production by foraging humpback whales

The Stellwagen Bank National Marine Sanctuary, located in an urbanized coastal area off the coast of Massachusetts in the United States, serves as an important foraging habitat for North Atlantic humpback whales (Megaptera novaeangliae). During the summer, large numbers of vessels are present in the vicinity of foraging humpback whales. Humpback whales produce a wide variety of low frequency( 12 hours between 2008-2012 showed decreased call rates and increased call frequency during close vessel passages. The response of the lone lactating female in the analyses was opposite of other whales, in that call rates increased ...

Vocal behavior of North Atlantic humpback whales during reunion events on Stellwagen Bank.

Humpback whales on their feeding grounds are typically found in small, ephemeral groups which have been hypothesized to form and separate to maximize foraging efficiency, but little is known about the functional mechanisms by which these groups change their composition. In this study, we test the hypothesis that specific vocalization types are associated with events where two or more individual humpback whales join to form a cohesive group on their summer feeding grounds. In the summer of 2008, 11 Dtags (a combined acoustic and movement recording tag) were attached to individual humpback whales on their feeding grounds in the Stellwagen Bank National Marine Sanctuary. Behavioral observations were collected from tagged animals at the surface and the timing of join events were recorded. Calls from the tagged whale and nearby associates were identified and analyzed to test for call rate changes between 10 min periods around joining events and 10 min control periods. Additional analyses included call type usa...

Characterizing the relative contributions of large vessels to total ocean noise fields: a case study using the Gerry E. Studds Stellwagen Bank National Marine Sanctuary

Understanding and mitigating the effects of underwater noise on marine species requires substantial information regarding acoustic contributions from shipping. In 2006, we used the U.S. Coast Guards Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary. AIS data were combined with low‐frequency acoustic data from an array of nine‐ten autonomous recording units deployed throughout 2006. Analysis of received sound levels (10‐1000 Hz, root‐mean squared decibels re 1 μPascal ± standard error) averaged 119.5 ± 0.3 at high traffic locations. High traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71‐141 Hz, root‐mean squared decibels re 1 μPascal ± standard error) for individual vessels ranged from 158 ± 2 (research vessel) to 186 ± 2 (oil tanker). Tankers were estimated to contribute two times more acoustic power to the re...