The acoustic repertoire of the Southern right whale,a quantitative analysis

Some 1274 southern right whale sounds were randomly selected and each sound was described by 10 acoustic variables. Two hundred and fifty of these sounds were also ‘labelled’ by the activity, size and sexual composition o the group producing them. Principal components analysis was performed on all the sounds' variables (1274×10) and on the variables for a subset of 823 sounds referred to as calls. Results of the principal components analyses indicate that the sounds can be divided into three major classes: blow sounds, slaps, and calls; and that the repertoire of calls is a continuum with certain types more common than others. The distribution of the ‘labelled’ sounds in the principal components analyses patterns revealed general associations between whale activities and the types of sounds produced.     

RESPONSE OF NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS) TO PLAYBACK OF CALLS RECORDED FROM SURFACE ACTIVE GROUPS IN BOTH THE NORTH AND SOUTH ATLANTIC

The surface active group (SAG) is the most obvious social interaction of the North Atlantic right whale ( Eubalaena glacialis ). SAGs are typically composed of an adult female with two or more males engaged in social behavior near the surface. Distinct calls, believed to be produced by the female, are associated with these groups. Calls recorded from three North Atlantic right whale SAGs and three South Atlantic right whale ( Eubalaena australis ) SAGs were played back to North Atlantic right whales to determine if these sounds are sufficient to attract males to the groups. Playbacks of gunshot sounds produced by North Atlantic right whales were used as a control stimulus. Thirty-six trials were carried out from 1999 to 2001 in the Bay of Fundy, Canada. Whales approached 27 of 31 SAG playbacks and 0 of 5 gunshot playbacks. Where sex was determined ( n = 28), all approaches to North Atlantic SAG recordings were by males. Individuals ( n = 22) of all age and sex classes approached South Atlantic SAG playbacks. These trials indicate that SAG calls from both populations are sufficient to attract right whales to SAGs and that males and females respond differently to stimuli from the North Atlantic. The difference in response to North and South Atlantic SAG stimuli was unexpected. Novelty, species differences in calls, and different seasonal or behavioral context for the recorded stimuli may be responsible for the differences in response.     

CHARACTERISTICS OF MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) PULSE TRAINS RECORDED NEAR PUERTO RICO

A nine-day acoustic and visual survey was conducted off the West Indies in March 1994 to study the pulse trains that were detected on SOSUS arrays throughout winter in deep water between the West Indies and Bermuda. During the survey, pulse train sounds were consistently recorded in an area 190–350 km northeast of Puerto Rico. Vocalizing animals were never visually observed, but visual sighting conditions were often poor and observation height was low. Pulse trains occurred in two basic forms. The "speed-up" pulse train was characterized by an accelerating series of pulses with energy in the 200–400 Hz band, with individual pulses lasting 40-60 msec. Speedup pulse trains started with average pulse rates of 1.5 pulses/sec, lasted 43.7 ± 6.0 sec, and ended with average pulse rates of 2.8 pulses/sec. The less common "slow-down" pulse train was characterized by a decelerating series of pulses with energy in the 250-350 Hz band. Slow-down pulse trains started at pulse rates averaging 4.5 pulses/sec, lasted 60.9 ± 5.8 sec, and ended with average pulse rates of 2.9 pulses/sec. We believe the recorded pulse trains are from minke whales based on careful reanalysis of, and comparison to, minke whale pulse-train sounds recorded in the Caribbean by Winn and Perkins (1976).     

REACTION OF FIN WHALES BALAENOPTERA PHYSALUS TO AN EARTHQUAKE

ABSTRACT

Whales living within seismically active regions are subject to intense disturbances from strong sounds produced by earthquakes that can kill or injure individuals. Nishimura & Clark (1993) relate the possible effects of underwater earthquake noise levels in marine mammals, adducing that T-phase source signal level (10- to 30- Hz range) can exceed 200 dB re: 1 μPa at 1 m, for a magnitude 4–5 earthquake, sounds audible to fin whales which produce low frequency sounds of 16–20/25–44 Hz over 0.5–1s, typically of 183 dB re: 1 μPa at 1 m. Here we present the response of a fin whale to a 5.5 Richter scale earthquake that took place on 22 February 2005, in the Gulf of California. The whale covered 13 km in 26 min (mean speed = 30.2 km/h). We deduce that the sound heard by this whale might have triggered the costly energy expenditure of high speed swimming as a seismic-escape response. These observations support the hypothesis of Richardson et al. (1995) that cetaceans may flee from loud sounds before they are injured, when exposed to noise in excess of 140 dB re: 1 μPa 1 m.     

SOUNDS OF A PYGMY RIGHT WHALE (CAPEREA MARGINATA)

Abstract: This is the first report of recordings of sounds from the pygmy right whale, Caperea marginata . The recordings were obtained in the presence of a juvenile in the harbor at Portland, on the southeastern corner of the Australian continent. Only one type of sound was heard-a short thump-like pulse or tone burst with a downsweep in frequency and decaying amplitude, with most energy between 60 and 120 Hz. The pulses occurred predominantly in pairs and once in a trio. The sounds are simpler than those of most baleen whales, but they show some similarity in characteristics. Source levels are in the lower end of the range determined for other species. There was no evidence to indicate the purpose of these sounds.     

INTER-OBSERVER COUNT DISCREPANCIES IN A SHORE-BASED CENSUS OF GRAY WHALES (ESCHRICHTIUS ROBUSTUS)

Estimations of gray whale abundance have generally assumed that shore-based observers record all whales migrating through the viewing area during periods uncompromised by visibility. We tested the repeatability of data collected at the standard gray whale census site at Granite Canyon Marine Laboratory in central California by using pairs of observers maintaining independent sighting records. Proximal shore sites were occupied 6 d (60 h) in January 1986 where one team counted 845 whales in 427 groups while the other team counted 990 whales in 477 groups. A comparison of the records showed that the first team missed 290 whales seen by the second team, and the second team missed 204 whales seen by the first team. The total number of whales in the viewing area was calculated for each team by the Petersen estimate, using mutually sighted whale groups as "recaptures". On average, observers recorded only 79% of the whales. More whales (68%) were missed when entire groups of whales were not seen rather than when groups were undercounted (32%). Visibility did not appear to affect observed rates of missed whales. Whales migrating at intermediate distances from the shore were less often missed than were those > 6 km or < 1 km offshore. This count discrepancy test confirms that an uncorrected calculation of population size for gray whales based on sighting records from solitary observers will be underestimated.     

Detection of baleen whale species using kernel dynamic mode decomposition-based feature extraction with a hidden Markov model

The negative effects of human activities within the ecological space of whales remains an issue of concern to marine ecologists. The accurate detection and subsequent classification of whale species are vital in mitigating these negative effects. Automatic detection techniques have come in handy for the efficient detection of the various whale species without human error. Hidden Markov model (HMM) remains one the most efficient detectors of whale species. However, its performance efficiency is greatly influenced by the feature vectors adapted with it. In this work, we propose the use of the kernel dynamic mode decomposition (kDMD) algorithm as a tool to extract features of baleen whale species, which are then adapted with HMM for their detection. Dynamic mode decomposition (DMD) is an eigendecomposition-based algorithm that is capable of extracting latent underlying features of non-linear signals such as those vocalised by whales. However, the underlying cost of DMD is the singular value decomposition (SVD), which adds significant complexity to the modes derivation steps. Thus, this work is introducing the kernel method into the DMD, in order to find a more efficient way of computing DMD without explicitly using the SVD algorithm. Furthermore, the feature formation steps in the original DMD was modified (mDMD) in this work, to make it more generic for datasets with sparse whale sound samples. The performance of the detectors was tested on datasets containing sounds of southern right whales (SRWs) and humpback whales. The results obtained show a high true positive rate (TPR), high precision (PREC) and low error rate (ERR) for both species. The performance of the three DMD-based feature-extraction methods were compared. The kDMD-HMM generally performed better than the mDMD-HMM and DMD-HMM detectors. The methods proposed here can be tailored for the automatic detection and classification of other vocalising animal species through their sounds.     

ESTIMATES OF SPERM WHALE ABUNDANCE IN THE NORTHEASTERN TEMPERATE PACIFIC FROM A COMBINED ACOUSTIC AND VISUAL SURVEY

We estimate the abundance of sperm whales in a 7.8 million km² study area in the eastern temperate North Pacific using data from a ship-based acoustic and visual line-transect survey in spring 1997. Sperm whales were detected acoustically using a hydrophone array towed at 15 km/h and 100 m depth. The hydrophone array was towed for 14,500 km, and locations were estimated acoustically for 45 distinct sperm whale groups. Whales producing slow clicks (>2-s period) were detected at greater distance (up to 37 km), and the estimation of effective strip widths was stratified based on initial click period. Visual survey effort (using 25° binoculars and naked eyes) covered 8,100 km in Beaufort sea states 0–5 and resulted in only eight sightings. The effective strip width for visual detections was estimated from previous surveys conducted using the same methods and similar vessels in the eastern Pacific. Estimated sperm whale abundance in the study area was not significantly different between acoustic (32,100, CV = 0.36) and visual (26,300, CV = 0.81) detection methods. Acoustic techniques substantially increased the number of sperm whales detected on this line-transect survey by increasing the range of detection and allowing nighttime surveys; however, visual observations were necessary for estimating group size.     

Hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and testes fibroblasts

Although hexavalent chromium is a known genotoxic agent in human and terrestrial mammals and is present in seawater and air, its effects on marine mammals including the endangered North Atlantic right whale are unknown and untested. The present study investigated the cytotoxic and genotoxic effects of hexavalent chromium in primary cultured North Atlantic right whale lung and testes fibroblasts and levels of total chromium in skin biopsies from North Atlantic right whales. Cytotoxicity was measured by clonogenic survival assay. Genotoxicity was measured as production of chromosome aberrations. Tissue chromium levels were determined from skin biopsies of healthy free-ranging whales in the Bay of Fundy using inductively coupled plasma optical emission spectroscopy. Hexavalent chromium-induced concentration-dependent increases in right whale lung and testes fibroblast cytotoxicity with the testes more sensitive to the cytotoxic effects. It also induced concentration-dependent increases in chromosomal aberrations in both cell types with no significant difference in sensitivity. Skin biopsy data indicate that North Atlantic right whales are exposed to chromium and accumulate a range of 4.9-10 microg Cr/g tissue with a mean of 7.1 microg/g. Hexavalent chromium is cytotoxic and genotoxic to North Atlantic right whale cells. The whales have tissue chromium levels that are concerning. These data support a hypothesis that chromium may be a concern for the health of the North Atlantic right whales. Considering these data with chromium chemistry, whale physiology and atmospheric chromium levels further suggest that inhalation may be an important exposure route.     

Wintering Habitat Model for the North Atlantic Right Whale (Eubalaena glacialis) in the Southeastern United States

The coastal waters off the southeastern United States (SEUS) are a primary wintering ground for the endangered North Atlantic right whale (Eubalaena glacialis), used by calving females along with other adult and juvenile whales. Management actions implemented in this area for the recovery of the right whale population rely on accurate habitat characterization and the ability to predict whale distribution over time. We developed a temporally dynamic habitat model to predict wintering right whale distribution in the SEUS using a generalized additive model framework and aerial survey data from 2003/2004 through 2012/2013. We built upon previous habitat models for right whales in the SEUS and include data from new aerial surveys that extend the spatial coverage of the analysis, particularly in the northern portion of this wintering ground. We summarized whale sightings, survey effort corrected for probability of whale detection, and environmental data at a semimonthly resolution. Consistent with previous studies, sea surface temperature (SST), water depth, and survey year were significant predictors of right whale relative abundance. Additionally, distance to shore, distance to the 22°C SST isotherm, and an interaction between time of year and latitude (to account for the latitudinal migration of whales) were also selected in the analysis presented here. Predictions from the model revealed that the location of preferred habitat differs within and between years in correspondence with variation in environmental conditions. Although cow-calf pairs were rarely sighted in the company of other whales, there was minimal evidence that the preferred habitat of cow-calf pairs was different than that of whale groups without calves at the scale of this study. The results of this updated habitat model can be used to inform management decisions for a migratory species in a dynamic oceanic environment.     

IDENTIFICATION OF WHALE SPECIES BY LIQUID CHROMATOGRAPHIC ANALYSIS OF SARCOPLASMIC PROTEINS

Liquid chromatography (LC) was applied to identify whale species by analyzing water-soluble sarcoplasmic proteins in skeletal muscles. Twenty-five samples from four baleen whale species (fin whale, sei whale, Bryde's whale, and minke whale) and eight toothed whale species (sperm whale, Baird's beaked whale, short-finned pilot whale, Dall's porpoise, northern right whale dolphin, Pacific white-sided dolphin, common dolphin, and striped dolphin) were analyzed. Water-soluble sarcoplasmic proteins were extracted from each sample and analyzed using a UV-VIS spectrophotometric detector at 280 nm and a pho-todiode array detector. The chromatographic profiles of each sample showed distinctive qualitative and quantitative characteristics for each whale species, making species identification possible. A photodiode array detector was useful for further accurate identification of whale species by obtaining the absorption spectra of separated protein peaks. These results suggest that the LC method is readily applicable to rapid, simple, and reliable identification of whale species.     

Quantification and genetic profiling of DNA isolated from free-floating feces of the North Atlantic right whale (Eubalaena glacialis)

Fecal analysis from the highly endangered North Atlantic right whale provides valuable information about health and reproductive parameters of individual animals. Genetically profiling the feces facilitates this connection when the sample originator is unknown. Although genetic analysis of feces collected in terrestrial systems has become well established, genetic studies of cetacean DNA are rare. Here, the use of free‐floating feces as a source of right whale DNA and the reliability of the genotypes produced are examined. On average, fecal extracts yielded 25 ng of DNA/mg dry weight, but less than 1% was right whale DNA. Although all samples were amplified using genus‐specific mitochondrial control region primers, the quantity of right whale DNA present was over estimated when compared to amplifications using nuclear primers. No correlation was found between the quantity of right whale DNA recovered and the duration the sample sat in the water. Composite microsatellite profiles from multiple amplifications of 28 fecal samples of known origin were consistent with profiles of the same individuals obtained from skin biopsies, however, the rate of allelic dropout varied depending on the amount of right whale DNA added. A screening and genotyping protocol for reliable genetic profiling based on fecal DNA quantification is presented.     

TWO TYPES OF BLUE WHALE CALLS RECORDED IN THE GULF OF ALASKA

At one time blue whales were found throughout the Gulf of Alaska, however, none have been sighted there in post-whaling era surveys. To determine if blue whales ( Balaenoptera musculus ) might now occur in the Gulf of Alaska, an array of hydrophones was deployed there in October 1999. Data were retrieved in May 2000 and in June 2001. Spectrograms from a random subsample comprising 15% of the ∼63,000 h of data were visually examined for blue whale calls. Call types attributed to both northeastern and northwestern Pacific blue whales were recorded. Both of these call types were recorded seasonally from the initial deployment date in October 1999 through the third week of December 1999 and then from July 2000 through mid-December 2000. Both call types were regularly recorded on the same hydrophone at the same time indicating clear temporal and spatial overlap of the animals producing these calls. Two blue whale call types were recorded in the Gulf of Alaska suggesting that perhaps two stocks use this area. The northeastern call type has now been documented from the equator up to at least 55°N in the eastern North Pacific.     

Estimating Cetacean Carrying Capacity Based on Spacing Behaviour

Conservation of large ocean wildlife requires an understanding of how they use space. In Western Australia, the humpback whale (Megaptera novaeangliae) population is growing at a minimum rate of 10% per year. An important consideration for conservation based management in space-limited environments, such as coastal resting areas, is the potential expansion in area use by humpback whales if the carrying capacity of existing areas is exceeded. Here we determined the theoretical carrying capacity of a known humpback resting area based on the spacing behaviour of pods, where a resting area is defined as a sheltered embayment along the coast. Two separate approaches were taken to estimate this distance. The first used the median nearest neighbour distance between pods in relatively dense areas, giving a spacing distance of 2.16 km (±0.94). The second estimated the spacing distance as the radius at which 50% of the population included no other pods, and was calculated as 1.93 km (range: 1.62–2.50 km). Using these values, the maximum number of pods able to fit into the resting area was 698 and 872 pods, respectively. Given an average observed pod size of 1.7 whales, this equates to a carrying capacity estimate of between 1187 and 1482 whales at any given point in time. This study demonstrates that whale pods do maintain a distance from each other, which may determine the number of animals that can occupy aggregation areas where space is limited. This requirement for space has implications when considering boundaries for protected areas or competition for space with the fishing and resources sectors.     

PATTERNS OF BOWHEAD WHALE DISTRIBUTION AND ABUNDANCE NEAR BARROW, ALASKA, IN FALL 1982-1989

Although the distribution and relative abundance of bowhead whales varied annually within the fall whaling area near Barrow, Alaska, the distance of whales from shore was not significantly different among years 1982-1989 (ANOVA, F = 0.5, P > 0.5). The minimum detectable distance for the ANOVA was 12 km (α= 0.05, β= 0.1). Annual median distance of random bowhead sightings from shore ranged from 23 to 39 km, with an eight-year median of 32 km. Highest annual bowhead sighting rates were positively associated with the proportion of feeding whales, indicating that whale feeding opportunities may affect the availability of whales within hunting range each fall.     

SEASONAL AND DIURNAL TRENDS OF CHORUSING HUMPBACK WHALES WINTERING IN WATERS OFF WESTERN MAUI

A portable data logger controlled by a Tattletale 7 microcontroller was used to record humpback whale choruses during the 1998 humpback whale winter season in Hawaii. The data logger sampled the sounds for four minutes every half hour using a digitizing rate of 2 kHz, and the data were stored on a hard disk. The results between January and April showed a peak in the sound pressure level between mid-February and mid-March. This peak of approximately 120 dB re 1 μPa coincided with the peak in the number of whales sighted by aerial survey on 7 March 1998. The choruses had spectral peaks at 315 Hz and 630 Hz. Some of the sounds at 630 Hz were second harmonics of the 315 Hz peak and others were not. The data also indicated a diurnal pattern in the sound pressure level, with levels at night significantly louder than the daytime levels. The sound levels began to increase during sunset and remained relatively high until sunrise, when they progressively decreased to a minimum. The nighttime peak occurred within an hour before and after midnight, and the daytime minimum occurred between 1100 and 1500. That more humpback whales appear to sing at night may reflect a switch to sexual advertisement as the primary male mating strategy at this time. It may also indicate that daylight and vision play key roles in the formation of competitive groups. It is suggested that the relative number of humpback whales in a given locale may be estimated by monitoring changes in sound pressure levels.     

Morphological specializations of baleen whales associated with hydrodynamic performance and ecological niche

Feeding behavior, prey type, and habitat appear to be associated with the morphological design of body, fluke, and flippers in baleen whales. Morphometric data from whaling records and recent stranding events were compiled, and morphometric parameters describing the body length, and fluke and flipper dimensions for an "average" blue whale Balaenoptera musculus, humpback whale Megaptera novaeangliae, gray whale Eschrichtius robustus, and right whale Eubalaena glacialis were determined. Body mass, body volume, body surface area, and fluke and flipper surface areas were estimated. The resultant morphological configurations lent themselves to the following classifications based on hydrodynamic principles: fast cruiser, slow cruiser, fast maneuverer, and slow maneuverer. Blue whales have highly streamlined bodies with small, high aspect ratio flippers and flukes for fast efficient cruising in the open ocean. On the other hand, the rotund right whale has large, high aspect ratio flukes for efficient slow speed cruising that is optimal for their continuous filter feeding technique. Humpbacks have large, high aspect ratio flippers and a large, low aspect ratio tail for quick acceleration and high-speed maneuvering which would help them catch their elusive prey, while gray whales have large, low aspect ratio flippers and flukes for enhanced low-speed maneuvering in complex coastal water habitats.     

ANALYSIS OF MITOCHONDRIAL DNA DIVERSITY WITHIN AND BETWEEN NORTH AND SOUTH ATLANTIC RIGHT WHALES

DNA sequences of the mitochondrial control region of 180 North Atlantic right whales ( Euhalaena glacialis ) and 16 South Atlantic right whales ( E. australis ) have been determined using a combination of direct DNA sequencing and single stranded conformation polymorphism (SSCP) analysis. Five haplotypes were found in E. glacialis , and 10 in E. australis , but none were shared, supporting the reproductive isolation and separate species status of the North and South Atlantic right whales. One haplotype in E, glacialis was found in only three males born before 1982 and this matriline will likely be lost soon. The nucleotide diversity estimates for the five North Atlantic right whale haplotypes was 0.6% and 2.0% for the 10 haplotypes found in the South Atlantic right whales. The average haplotypic diversity was 0.87 in E. glacialis and 0.96 in E. australis , which is consistent with other studies showing a lower level of genetic variation in the North Atlantic right whale. Phylogenetic analysis identified two major assemblages of haplotypes in E. australis from the samples collected from Peninsula Valdes, suggesting a mixing of two historically divergent populations. Using genetic distance measurements with a divergence rate of 0.5%–1.0%/myr, we estimate E. glacialis diverged from E. australis 3–12.5 mya.     

REACTIONS OF CAPTIVE HARBOR PORPOISES (PHOCOENA PHOCOENA) TO PINGER-LIKE SOUNDS

Pingers on gill nets can reduce bycatch of harbor porpoises. If harbor porpoises habituate to pingers, the effect may be reduced or lost. Two captive harbor porpoises were exposed to three sound types. All sounds were in the frequency band from 100 kHz to 140 kHz, 200 ms long, and presented once per 4 s. The source level was 153 dB re 1 μPa RMS at 1 m. Each session consisted of a 10‐min presound, a 5‐min sound, and a 10‐min postsound period. Behavior was recorded on video and on dataloggers placed on the dorsal fin of one animal. The loggers recorded heart rate, swimming speed, dive duration, and depth. The animals responded most strongly to the initial presentations of a sound. Surface time decreased, the heart rate dropped below the normal bradycardia, and echolocation activity decreased. The reactions of both animals diminished rapidly in the following sessions. Should the waning of responsiveness apply to wild animals, porpoises may adapt to the sounds but still avoid nets, or the bycatch may increase after some time. The success of long‐term use of pingers may then depend on the variety of sounds and rates of exposure.     

Cetacean mitochondrial DNA control region: sequences of all extant baleen whales and two sperm whale species

The sequence of the mitochondrial control region was determined in all 10 extant species commonly assigned to the suborder Mysticeti (baleen or whalebone whales) and to two odontocete (toothed whale) species (the sperm and the pygmy sperm whale). In the mysticetes, both the length and the sequence of the control region were very similar, with differences occurring primarily in the first approximately 160 bp of the 5' end of the L-strand of the region. There were marked differences between the mysticete and sperm whale sequences and also between the two sperm whales. The control region, less its variable portion, was used in a comparison including the 10 mysticete sequences plus the same region of an Antarctic minke whale specimen and the two sperm whales. The difference between the minke whales from the North Atlantic and the Antarctic was greater than that between any acknowledged species belonging to the same genus (Balaenoptera). The difference was similar to that between the families Balaenopteridae (rorquals) and Eschrichtiidae (gray whales). The findings suggest that the Antarctic minke whale should have a full species status, B. bonaerensis. Parsimony analysis separated the bowhead and the right whale (family Balaenidae) from all remaining mysticetes, including the pygmy right whale. The pygmy right whale is usually included in family Balaenidae. The analysis revealed a close relationship between the gray whale (family Eschrichtiidae) sequence and those of the rorquals (family Balaenopteridae). The gray whale was included in a clade together with the sei, Bryde's, fin, blue, and humpback whales. This clade was separated from the two minke whale types, which branched together.