Narwhals react to ship noise and airgun pulses embedded in background noise

Anthropogenic activities are increasing in the Arctic, posing a threat to niche-conservative species with high seasonal site fidelity, such as the narwhal Monodon monoceros. In this controlled sound exposure study, six narwhals were live-captured and instrumented with animal-borne tags providing movement and behavioural data, and exposed to concurrent ship noise and airgun pulses. All narwhals reacted to sound exposure with reduced buzzing rates, where the response was dependent on the magnitude of exposure defined as 1/distance to ship. Buzzing rate was halved at 12 km from the ship, and whales ceased foraging at 7–8 km. Effects of exposure could be detected at distances > 40 km from the ship.At only a few kilometres from the ship, the received high-frequency cetacean weighted sound exposure levels were below background noise indicating extreme sensitivity of narwhals towards sound disturbance and demonstrating their ability to detect signals embedded in background noise. The narwhal''s reactions to sustained disturbance may have a plethora of consequences both at individual and population levels. The observed reactions of the whales demonstrate their auditory sensitivity but also emphasize, that anthropogenic activities in pristine narwhal habitats needs to be managed carefully if healthy narwhal populations are to be maintained.     

THE EFFECT OF VESSEL NOISE ON THE VOCAL BEHAVIOR OF BELUGAS IN THE ST. LAWRENCE RIVER ESTUARY,CANADA

During June-July 1991, we monitored the vocal behavior of belugas before, during, and after exposure to noise from a small motorboat and a ferry to determine if there were any consistent patterns in their vocal behavior when exposed to these two familiar, but different sources of potential disturbance. Vocal responses were observed in all trials and were more persistent when whales were exposed to the ferry than to the small boat. These included (1) a progressive reduction in calling rate from 3.4–10.5 calls/whale/min to 0.0 or <1.0 calls/whale/min while vessels were approaching; (2) brief increases in the emission of falling tonal calls and the theree pulsed-tone call types; (3) at distances <1 km, an increase in the repetition of specific calls, and (4) a shift in frequency bands used by vocalizing animals from a mean frequency of 3.6 kHz prior to exposure to noise to frequencies of 5.2-8.8 kHz when vessels were close to the whales.     

An estimate of the fraction of belugas (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>) in the Canadian high Arctic that winter in West Greenland

Five belugas, or white whales (Delphinapterus leucas), were tracked by satellite from Creswell Bay, Somerset Island, in the Canadian high Arctic towards West Greenland in autumn 2001. After 1 October, three of the whales stayed in the North Water polynya and the other two whales moved to West Greenland. One of the whales that moved to Greenland migrated south along the west coast, following a route and timing similar to another beluga tracked in 1996. The belugas that moved towards West Greenland from Canada did so before or near 1 October. The movements of both these whales followed a similar timing and assumed migratory route of belugas hunted in autumn in West Greenland. In Greenland, the hunt begins in September, where the first whales are taken in the northernmost community of Qaanaaq. Hunting takes place farther south in Upernavik in October, and finally in November and December, belugas are taken even farther south in Uummannaq and Disko Bay. The whales that remain in the North Water after 1 October most likely do not contribute to the harvest in West Greenland. Based on the total number of belugas satellite-tracked in Canada between 1995 and 2001 with tags that lasted beyond 1 October, approximately 0.15 (95% CI 0.06-0.35; n=26) of the summering stock of belugas in the Canadian high Arctic move to West Greenland for the winter. Genetic studies have indicated that belugas moving east through Lancaster Sound are significantly differentiated from belugas taken in the autumn hunt in West Greenland. These conflicting results suggest molecular genetics cannot be solely relied on to reveal the stock identity of these belugas.     

Serologic evidence of influenza A infection in marine mammals of arctic Canada.

A serologic survey of influenza A antibodies was undertaken on 1,611 blood samples from five species of marine mammals collected from Arctic Canada from 1984-98. Sampling was done in 24 locations throughout the Canadian Arctic encompassing Sachs Harbor (72 degrees N, 125 degrees W), Northwest Territories in the west to Loks Land (63 degrees N, 64 degrees W), Nunavut in the east, to Eureka (80 degrees N, 86 degrees W), Nunavut in the north to Sanikiluaq (56 degrees N, 79 degrees W), Nunavut in the south. A competitive ELISA using a monoclonal antibody (Mab) against influenza A nucleoprotein (NP) was used. Five of 418 (1.2%) belugas (Delphinapterus leucas) and 23 of 903 (2.5%) ringed seals (Phoca hispida) were serologically positive. None of the 210 walruses (Odobenus rosmarus rosmarus), 76 narwhals (Monodon monoceros) and four bowhead whales (Balaena mysticetus) had detectable antibodies to influenza A. Positive belugas were identified from communities on southeast Baffin Island while positive ringed seals came from communities in the eastern, western and high Arctic. Virus isolation attempts on lung tissue from a seropositive beluga were unsuccessful. We believe that influenza A infection in marine mammals is sporadic, the infection is probably self-limiting, and it may not be able to be maintained in these animals. Although the predominant hemagglutinin (H) type was not determined and therefore the pathogenicity of the strains to humans is unknown, the hunting and consumption of marine mammals by the Inuit, may put them at risk for influenza A infection.     

AIRCRAFT SOUND AND DISTURBANCE TO BOWHEAD AND BELUGA WHALES DURING SPRING MIGRATION IN THE ALASKAN BEAUFORT SEA

Short‐term behavioral responses of bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas) to a Bell 212 helicopter and Twin Otter fixed‐wing aircraft were observed opportunistically during four spring seasons (1989–1991 and 1994). Behaviors classified as reactions consisted of short surfacings, immediate dives or turns, changes in behavior state, vigorous swimming, and breaching. The helicopter elicited fewer detectable responses by bowheads (14% of 63 groups) than by belugas (38% of 40). Most observed reactions by bowheads (63%) and belugas (86%) occurred when the helicopter was at altitudes ≤150 m and lateral distances ≤250 m. Belugas reacted significantly more frequently during overflights at lateral distances ≤250 m than at longer lateral distances (P= 0.004). When the helicopter was on the ice with engines running, 7 of 14 groups of belugas reacted, up to 320 m away, sometimes with small‐scale (≤100 m) diversion; only 1 of 8 groups of bowheads reacted. For the fixed‐wing aircraft, few bowheads (2.2%) or belugas (3.2%) were observed to react to overflights at altitudes 60–460 m. Most observed reactions by bowheads (73%) and belugas (70%) occurred when the fixed‐wing aircraft was at altitudes ≤182 m and lateral distances ≤250 m. However, the proportions reacting, especially to low‐altitude flights (e. g., ≤182 m), were underestimated for both species because observation opportunities were brief. Even so, reactions were more common when the aircraft was low (≤182 m): P= 0.009 for belugas, P= 0.06 for bowheads. There was little if any reaction by bowheads when the aircraft circled at altitude 460 m and radius 1 km. Aircraft sounds measured underwater at depths 3 m and 18 m showed that a Bell 212 helicopter was 7–17.5 dB noisier than a Twin Otter (10–500 Hz band). Bell 212 sound consisted mainly of main rotor tones ahead of the helicopter and tail rotor tones behind it. Twin Otter sound contained fewer prominent tones. Peak sound level as received underwater was inversely related to aircraft altitude, and received levels at 3 m depth averaged 2.5 dB higher than at 18 m depth. The dominant low‐frequency components of aircraft sound are presumed to be readily audible to bowheads. For belugas, these components may be inaudible, or at most only weakly audible. Mid‐frequency sound components, visual cues, or both, are probably important in eliciting beluga reactions to aircraft.     

Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation

Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea (‘Chukchi’) and Eastern Beaufort Sea (‘Beaufort’) beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze‐up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between ‘early’ (1993–2002) and ‘late’ (2004–2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze‐up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze‐up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr^?1) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.     

Identification of sex in Cetaceans by multiplexing with three ZFX and ZFY specific primers

We sequenced 540 nucleotides of the last exon in the ZFY/ZFX gene in two males and two females for eight cetacean species; four odontocetes (toothed whales) and four mysticetes (baleen whales). Based upon the obtained nucleotide sequences, we designed two sets of oligonucleotide primers for specific amplification of the ZFX and the ZFY sequence in odontocetes and mysticetes, respectively. Each primer set consisted of three oligonucleotides; one forward-orientated primer, which anneals to the ZFY as well as the ZFX sequence, and two reverse-orientated primers that anneal to either the ZFX or the ZFY sequence. The resulting two amplification products (specific for the ZFY and ZFX sequences) can be distinguished by gel-electrophoresis through 2% NuSieve™. The accuracy of the technique was tested by determination of gender in 214 individuals of known sex. Finally we applied the technique to determine the sex of 3570 cetacean specimens; 2284 humpback whales, 315 fin whales, 37 blue whales, 7 minke whales, as well as 592 belugas, 335 narwhals and 25 harbour porpoises.     

Large numbers of marine mammals winter in the North Water polynya

The importance of the North Water polynya in Smith Sound as an overwintering area for marine mammals has been questioned. One way to address the issue is to assess the abundance of selected marine mammals that are present during winter in the North Water. Visual aerial surveys involving double observer platforms were conducted over the eastern part of the North Water polynya in April 2014. Four species of marine mammals were included in strip-census estimation of abundance. Perception bias was addressed using a double-platform survey protocol, a Chapman mark–recapture estimator for whales, seals and walruses (Odobenus rosmarus) on ice and a mark–recapture distance sampling estimation technique for walruses in water. Availability bias was addressed by correcting abundance estimates by the percentage of time animals detected in water that were available for detection at the surface. The resulting estimates suggested that 2544 walruses (95 % CI 1513–4279), 6005 bearded seals (Erignathus barbatus, 95 % CI 4070–8858), 2324 belugas (Delphinapterus leucas, 95 % CI 968–5575) and 3059 narwhals (Monodon monoceros, 95 % CI 1760–5316) wintered in the eastern part of the North Water polynya in April 2014. The walrus estimate is larger than previous summer estimates, and it emphasizes the importance of the habitat along the Greenland coast as a walrus wintering ground. The estimate of belugas is likely negatively biased due to the partial coverage of the potential habitat. The estimate of narwhals is large compared to the few previous observations of narwhals in winter in the North Water, and it demonstrates that large numbers of narwhals winter there. The overall conclusion is that the North Water is indeed an important wintering area for at least walruses, belugas, narwhals and bearded seals.     

DESCRIPTION OF AN ANOMALOUS MONODONTID SKULL FROM WEST GREENLAND: A POSSIBLE HYBRID?

Abstract: The complete skull of an anomalous odontocete cetacean from outer Disko Bay, West Greenland, is described and compared with the skulls of adult narwhals, Monodon monoceros , and belugas, Delphinapterus leucas . The anomalous whale's skull is much larger than those of normal narwhals and belugas. In particular, the rostrum and mandibles are relatively long and massive. The dentition is unlike that of any known cetacean, but some features of the teeth are considered analogous to those of both narwhals and belugas. The intermediate characteristics of the skull and dentition are consistent with the hypothesis that the anomalous whale was a narwhal-beluga hybrid.     

Evidence that ship noise increases stress in right whales

Baleen whales (Mysticeti) communicate using low-frequency acoustic signals. These long-wavelength sounds can be detected over hundreds of kilometres, potentially allowing contact over large distances. Low-frequency noise from large ships (20-200 Hz) overlaps acoustic signals used by baleen whales, and increased levels of underwater noise have been documented in areas with high shipping traffic. Reported responses of whales to increased noise include: habitat displacement, behavioural changes and alterations in the intensity, frequency and intervals of calls. However, it has been unclear whether exposure to noise results in physiological responses that may lead to significant consequences for individuals or populations. Here, we show that reduced ship traffic in the Bay of Fundy, Canada, following the events of 11 September 2001, resulted in a 6 dB decrease in underwater noise with a significant reduction below 150 Hz. This noise reduction was associated with decreased baseline levels of stress-related faecal hormone metabolites (glucocorticoids) in North Atlantic right whales (Eubalaena glacialis). This is the first evidence that exposure to low-frequency ship noise may be associated with chronic stress in whales, and has implications for all baleen whales in heavy ship traffic areas, and for recovery of this endangered right whale population.     

Behavior and blood catecholamines of captive belugas during playbacks of noise from an oil drilling platform

Belugas (Delphinapterus leucas) depend on sounds for communication and echolocation. To address the concerns that noise from oil platforms may have adverse effects, we examined behavioral responses of four captive belugas to playbacks of noise from SEDCO 708, a semi-submersible drilling platform. Swim patterns, social groups, and respiration/dive rates were not statistically different before and during playbacks. We assayed levels of blood catecholamines before and after playbacks as a measure of stress. Blood epinephrine and norepinephrine levels measured immediately after playbacks were not elevated. Using the parameters we selected, we could not detect any short-term behavioral or physiological effects of drilling noise playbacks on these captive belugas. However, care should be taken in extrapolating these results to the behavior of wild belugas around oil platforms.     

Zinc,cadmium, mercury and selenium in minke whales,belugas and narwhals from West Greenland

Summary Samples of muscle, liver and kidney from 24 minke whales (Balaenoptera acutorostrata), 43 belugas (Delphinapterus leucas), and 98 narwhals (Monodon monoceros) were analyzed for zinc, cadmium, mercury, and selenium. Highly significant age accumulation of mercury was found. A lower level of significance of age accumulation of cadmium in belugas and narwhals is probably due to the fact that some of the highest cadmium concentrations are in subadults and young adults. The maximum concentrations of cadmium and mercury are very high: 1.68, 73.7, and 125 g cadmium, and 9.88, 42.8, and 4.61 g mercury per g wet weight of narwhal muscle, liver and kidney, respectively. The cadmium concentrations are correlated in the three organs, as are mercury and to a lesser extent selenium concentrations. The concentrations of mercury and selenium in liver are highly correlated.     

Some like it cold: Temperature‐dependent habitat selection by narwhals

The narwhal (Monodon monoceros) is a high‐Arctic species inhabiting areas that are experiencing increases in sea temperatures, which together with reduction in sea ice are expected to modify the niches of several Arctic marine apex predators. The Scoresby Sound fjord complex in East Greenland is the summer residence for an isolated population of narwhals. The movements of 12 whales instrumented with Fastloc‐GPS transmitters were studied during summer in Scoresby Sound and at their offshore winter ground in 2017–2019. An additional four narwhals provided detailed hydrographic profiles on both summer and winter grounds. Data on diving of the whales were obtained from 20 satellite‐linked time‐depth recorders and 16 Acousonde? recorders that also provided information on the temperature and depth of buzzes. In summer, the foraging whales targeted depths between 300 and 850 m where the preferred areas visited by the whales had temperatures ranging between 0.6 and 1.5°C (mean = 1.1°C, SD = 0.22). The highest probability of buzzing activity during summer was at a temperature of 0.7°C and at depths > 300 m. The whales targeted similar depths at their offshore winter ground where the temperature was slightly higher (range: 0.7–1.7°C, mean = 1.3°C, SD = 0.29). Both the probability of buzzing events and the spatial distribution of the whales in both seasons demonstrated a preferential selection of cold water. This was particularly pronounced in winter where cold coastal water was selected and warm Atlantic water farther offshore was avoided. It is unknown if the small temperature niche of whales while feeding is because prey is concentrated at these temperature gradients and is easier to capture at low temperatures, or because there are limitations in the thermoregulation of the whales. In any case, the small niche requirements together with their strong site fidelity emphasize the sensitivity of narwhals to changes in the thermal characteristics of their habitats.     

High Source Levels and Small Active Space of High-Pitched Song in Bowhead Whales (Balaena mysticetus)

The low-frequency, powerful vocalizations of blue and fin whales may potentially be detected by conspecifics across entire ocean basins. In contrast, humpback and bowhead whales produce equally powerful, but more complex broadband vocalizations composed of higher frequencies that suffer from higher attenuation. Here we evaluate the active space of high frequency song notes of bowhead whales (Balaena mysticetus) in Western Greenland using measurements of song source levels and ambient noise. Four independent, GPS-synchronized hydrophones were deployed through holes in the ice to localize vocalizing bowhead whales, estimate source levels and measure ambient noise. The song had a mean apparent source level of 185±2 dB rms re 1 µPa @ 1 m and a high mean centroid frequency of 444±48 Hz. Using measured ambient noise levels in the area and Arctic sound spreading models, the estimated active space of these song notes is between 40 and 130 km, an order of magnitude smaller than the estimated active space of low frequency blue and fin whale songs produced at similar source levels and for similar noise conditions. We propose that bowhead whales spatially compensate for their smaller communication range through mating aggregations that co-evolved with broadband song to form a complex and dynamic acoustically mediated sexual display.     

Sequence variation at the major histocompatibility complex locus DQ beta in beluga whales (Delphinapterus leucas) [published erratum appears in Mol Biol Evol 1995 Nov;12(6):1174]

Genetic variation at the Major Histocompatibility Complex locus DQ beta was analyzed in 233 beluga whales (Delphinapterus leucas) from seven populations: St. Lawrence Estuary, eastern Beaufort Sea, eastern Chukchi Sea, western Hudson Bay, eastern Hudson Bay, southeastern Baffin Island, and High Arctic and in 12 narwhals (Monodon monoceros) sympatric with the High Arctic beluga population. Variation was assessed by amplification of the exon coding for the peptide binding region via the polymerase chain reaction, followed by either cloning and DNA sequencing or single-stranded conformation polymorphism analysis. Five alleles were found across the beluga populations and one in the narwhal. Pairwise comparisons of these alleles showed a 5:1 ratio of nonsynonymous to synonymous substitutions per site leading to eight amino acid differences, five of which were nonconservative substitutions, centered around positions previously shown to be important for peptide binding. Although the amount of allelic variation is low when compared with terrestrial mammals, the nature of the substitutions in the peptide binding sites indicates an important role for the DQ beta locus in the cellular immune response of beluga whales. Comparisons of allele frequencies among populations show the High Arctic population to be different (P < or = .005) from the other beluga populations surveyed. In these other populations an allele, Dele-DQ beta*0101-2, was found in 98% of the animals, while in the High Arctic it was found in only 52% of the animals. Two other alleles were found at high frequencies in the High Arctic population, one being very similar to the single allele found in narwhal.      

Autumn movements, home ranges, and winter density of narwhals (Monodon monoceros) tagged in Tremblay Sound, Baffin Island

Seven narwhals (Monodon monoceros) were instrumented with satellite transmitters in Tremblay Sound, northeast Canada in August 1999. The whales were tracked for 5-218 days with positions received until 17 March 2000. All whales stayed in the fjord system where they were tagged until the end of August. Three whales went northwest visiting adjacent fjords before moving south, together with the three other whales, along the east coast of Baffin Island. The narwhals arrived on the wintering ground in northern Davis Strait in late October. Speed and range of movements declined once the wintering ground was reached. Dive depths increased from summer to autumn, and reached at least 1,500 m. Late summer and winter kernel home ranges were approximately 3,400 km² and 12,000 km², respectively. The relative abundance of whales on the wintering ground was 936 narwhals. Assuming that the home range defines the winter distribution of the stock, an estimated 5,348 narwhals (corrected for perception and availability bias) were present in this area.     

SEASONAL OCCURRENCE OF SPERM WHALE (PHYSETER MACROCEPHALUS) SOUNDS IN THE GULF OF ALASKA, 1999–2001

An acoustic survey for sperm whales was conducted in the Gulf of Alaska. Six autonomous hydrophones continuously recorded sound signals below 500 Hz from October 1999 to May 2001. After recovery, recordings were processed using an automatic process to detect usual clicks of sperm whales. The detection algorithm equalized background noise, summed the data in a frequency band, and then used autocorrelation to detect the whales' highly regular clicks. Detections were checked manually, revealing that 98% of detections did contain clicks. Results indicate that sperm whales are present in the Gulf of Alaska year-round; this result extends what is known from whaling data, which were gathered principally in summer. Sperm whales were more common in summer than winter by a factor of roughly two, and occurred less often at the westernmost site surveyed (52°N, 157°W) than elsewhere in the Gulf. This is the first study of sperm whales based exclusively on remote acoustic sensing. This methodology is feasible because sperm whale clicks extend to frequencies (∼100 Hz) low enough to be recorded by low-sample-rate instruments that operate continuously, and because the detection algorithm has a low false-detection rate. The methodology may be replicated to facilitate comparisons between different time periods and geographic regions.     

Exposure to seismic survey alters blue whale acoustic communication

The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This response presumably represents a compensatory behaviour to the elevated ambient noise from seismic survey operations.     

Comparing marine mammal acoustic habitats in Atlantic and Pacific sectors of the High Arctic: year-long records from Fram Strait and the Chukchi Plateau

During the International Polar Year (IPY), acoustic recorders were deployed on oceanographic moorings in Fram Strait and on the Chukchi Plateau, representing the first coordinated year-round sampling of underwater acoustic habitats at two sites in the High Arctic. Examination of species-specific marine mammal calls recorded from autumn 2008–2009 revealed distinctly different acoustic habitats at each site. Overall, the Fram Strait site was acoustically complex compared with the Chukchi Plateau site. In Fram Strait, calls from bowhead whales (Balaena mysticetus) and a variety of toothed whales (odontocetes) were recorded year-round, as were airgun pulses from seismic surveys. In addition, calls from blue whales (Balaenoptera musculus) and fin whales (B. physalus) were recorded from June to October and August to March, respectively. Conversely, at the Chukchi Plateau site, beluga (Delphinapterus leucas) and bowhead whale calls were recorded primarily from May to August, with airgun signals detected only in September–October. Ribbon seal (Phoca fasciata) calls were detected in October–November, with no marine mammals calls at all recorded from December to February. Of note, ice-adapted bearded seals (Erignathus barbatus) were recorded at both sites, primarily in spring and summer, corresponding with the mating season for that species. Differences in acoustic habitats between the two sites were related to contrasts in sea ice cover, temperature, patterns of ocean circulation and contributions from anthropogenic noise sources. These data provide a provisional baseline for the comparison of underwater acoustic habitats between Pacific and Atlantic sectors of the High Arctic.     

Individual right whales call louder in increased environmental noise

The ability to modify vocalizations to compensate for environmental noise is critical for successful communication in a dynamic acoustic environment. Many marine species rely on sound for vital life functions including communication, navigation and feeding. The impacts of significant increases in ocean noise levels from human activities are a current area of concern for the conservation of marine mammals. Here, we document changes in calling behaviour by individual endangered North Atlantic right whales (Eubalaena glacialis) in increased background noise. Right whales, like several bird and primate species, respond to periods of increased noise by increasing the amplitude of their calls. This behaviour may help maintain the communication range with conspecifics during periods of increased noise. These call modifications have implications for conservation efforts for right whales, affecting both the way whales use sound to communicate and our ability to detect them with passive acoustic monitoring systems.