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At least 19 recordsLinked to original sources
PubMed1990

Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales.

Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations.

Animals↗
PubMed2004

Intra- and inter-species differences in persistent organic contaminants in the blubber of blue whales and humpback whales from the Gulf of St. Lawrence, Canada.

Biopsy samples of blubber from adult male and female blue whales, and from female and young-of-the-year humpback whales were collected during the summers of 1992-1999 in the Gulf of St. Lawrence, Canada. In blue whales, concentrations of 25 PCB congeners, DDT and metabolites and several other organochlorine compounds were present at higher concentrations in the blubber of males relative to females; reflecting maternal transfer of these persistent contaminants from females into young. Sex-related differences in concentrations were not observed with less persistent contaminants, such as HCHs. In humpback whale samples, there were no significant differences in the concentrations of PCBs and organochlorine compounds in the blubber of females and calves. These data indicate that calves quickly bioaccumulate contaminants by transplacental and lactational routes to concentrations that are in equilibrium with females. In comparisons between contaminant concentrations and patterns in the blubber of female blue and humpback whales, there were no significant differences in concentrations, but the proportions of some PCB congeners, HCH isomers, and DDT and its metabolites were different in the two baleen whale species. These may reflect differences in the diet of the two species, since fish comprise a large part of the diet of humpback whales and blue whales feed exclusively on euphausiid crustaceans (i.e. krill).

Adipose Tissue↗
PubMed1999

Environmental constraints on sound transmission by humpback whales.

Singing humpback whales in Hawaii produce a variety of sounds at high source levels (ca. 185 dB re: 1 microPa), in coastal waters 15-500 m deep. These sounds are attenuated and distorted as they propagate away from a singer, limiting the utilizable range of the sounds. In the current study, simulations based on normal-mode theory were used to investigate how the effects of shallow-water propagation constrain humpback whales' use of sound. It is shown that humpbacks can greatly affect transmission range by adjusting their positions and sounds in response to environmental factors. Source depth, in particular, is shown to be a major determinant of which frequencies propagate the farthest. A preliminary analysis of range-dependent distortion suggests that spectral cues can potentially provide listening whales with information about how far a sound has traveled.

Animals↗
PubMedDate not supplied

Population characteristics of DNA fingerprints in humpback whales (Megaptera novaeangliae).

Humpback whales exhibit a remarkable social organization that is characterized by seasonal long-distance migration (> 10,000 km/year) between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical or near-tropical waters. All populations are currently considered endangered as a result of intensive commercial exploitation during the last 200 years. Using three hypervariable minisatellite DNA probes (33.15, 3'HVR, and M13) originally developed for studies of human genetic variation, we examined genetic variation within and among three regional subpopulations of humpback whales from the North Pacific and one from the North Atlantic oceans. Analysis of DNA extracted from skin tissues collected by biopsy darting from free-ranging whales revealed considerable variation in each subpopulation. The extent of this variation argues against a recent history of inbreeding among humpback whales as a result of nineteenth- and twentieth-century hunting. A canonical variate analysis suggested a relationship between scaled genetic distance, based on similarities of DNA fingerprints, and geographic distance (i.e., longitude of regional subpopulation). Significant categorical differences were found between the two oceanic populations using a multivariate analysis of variance (MANOVA) with a modification of the Mantel nonparametric permutation test. The relationship between DNA fingerprint similarities and geographic distance suggests that nuclear gene flow between regional subpopulations within the North Pacific is restricted by relatively low rates of migratory interchange between breeding grounds or assortative mating on common wintering grounds.

Animals↗
PubMed1995

Hydrodynamic design of the humpback whale flipper.

The humpback whale (Megaptera novaeangliae) is reported to use its elongate pectoral flippers during swimming maneuvers. The morphology of the flipper from a 9.02-m whale was evaluated with regard to this hydrodynamic function. The flipper had a wing-like, high aspect ratio planform. Rounded tubercles were regularly interspersed along the flipper's leading edge. The flipper was cut into 71 2.5-cm cross-sections and photographed. Except for sections near the distal tip, flipper sections were symmetrical with no camber. Flipper sections had a blunt, rounded leading edge and a highly tapered trailing edge. Placement of the maximum thickness placement for each cross-section varied from 49% of chord at the tip to 19% at mid-span. Section thickness ratio averaged 0.23 with a range of 0.20-0.28. The humpback whale flipper had a cross-sectional design typical of manufactured aerodynamic foils for lift generation. The morphology and placement of leading edge tubercles suggest that they function as enhanced lift devices to control flow over the flipper and maintain lift at high angles of attack. The morphology of the humpback whale flipper suggests that it is adapted for high maneuverability associated with the whale's unique feeding behavior.

Adaptation, Biological↗
PubMed1986

Sounds, source levels, and associated behavior of humpback whales, southeast Alaska.

Humpback whales in Southeast Alaskan waters produced five categories of sounds: moans, grunts, pulse trains, blowhole-associated sounds, and surface impacts. Frequencies (Hz) of moans and grunts were 20-1900. Major energy in low-frequency pulse trains was in a band of 25-80 Hz with pulse duration of 300-400 ms. Blowhole-associated sounds, recorded as transiting whales encountered one another, were of two types: shrieks, 555-2000 Hz, and trumpetlike horn blasts with fundamental at 414 Hz (median). Pulses and spread spectrum noise were associated with gas bubble formation and explosive bursts, respectively, in connection with spiral feeding maneuvers. Surface impacts resulted from fluke or flipper slaps in sequences of 3-21 sounds. Source levels ranged from 162 (low-frequency pulse trains) to 192 dB (surface impacts), re: 1 microPa, 1 m. Songs, commonly heard on winter breeding grounds, were absent from our recordings. Feeding and perhaps certain other whale activities can be monitored based on sound production.

Animals↗
PubMed2002

Social structure in migrating humpback whales (Megaptera novaeangliae).

Although largely solitary, humpback whales exhibit a number of behaviours where individuals co-operate with one another, for example during bubble net feeding. Such cases could be due to reciprocal altruism brought on by exceptional circumstances, for example the presence of abundant shoaling fish. An alternative explanation is that these behaviours have evolved through kin selection. With little restriction to either communication or movement, diffuse groups of relatives could maintain some form of social organization without the need to travel in tight-nit units. To try to distinguish between these hypotheses, we took advantage of the fact that migrating humpback whales often swim together in small groups. If kin selection is important in humpback whale biology, these groups should be enriched for relatives. Consequently, we analysed biopsy samples from 57 groups of humpback whales migrating off Eastern Australia in 1992. A total of 142 whales were screened for eight microsatellite markers. Mitochondrial DNA sequences (371 bp) were also used to verify and assist kinship identification. Our data add support to the notion that mothers travel with their offspring for the first year of the calf's life. However, beyond the presence of mother-calf/yearling pairs, no obvious relatedness pattern was found among whales sampled either in the same pod or on the same day. Levels of relatedness did not vary between migratory phases (towards or away from the breeding ground), nor between the two sexes considered either overall or in the north or south migrations separately. These findings suggest that, if any social organization does exist, it is formed transiently when needed rather than being a constant feature of the population, and hence is more likely based on reciprocal altruism than kin selection.

Animal Migration↗
PubMed1995

Evidence for a sex-segregated migration in the humpback whale (Megaptera novaeangliae).

Existing population models for humpback whales assume that all individuals within a population undertake the annual migration from feeding areas in high latitudes to breeding areas in tropical waters. An excess of males was recorded in the commercial whaling catches near breeding areas in the southern hemisphere, but no account of this was taken in developing population models, because it was believed that this bias was a result of whalers selecting against females with young calves. Here we demonstrate that the sex ratio of migrating humpback whales near a breeding area is highly skewed towards males. A biopsy study carried out in 1992 throughout the northward and southward migrations revealed a sex ratio of 2.4 males: 1 female in the population of humpback whales migrating along the east Australian coast (n = 180). A reanalysis of the catches made during commercial whaling in this and other areas of the southern hemisphere gave a sex ratio of the same order. The most plausible explanation, supported by some evidence, is that some females remain in the feeding areas throughout winter. The results reported here show that existing management models require major revision to take account of these findings.

Animals↗
PubMed2004

Song copying by humpback whales: themes and variations.

Male humpback whales (Megaptera novaeangliae) produce long, structured sequences of sound underwater, commonly called "songs." Humpbacks progressively modify their songs over time in ways that suggest that individuals are copying song elements that they hear being used by other singers. Little is known about the factors that determine how whales learn from their auditory experiences. Song learning in birds is better understood and appears to be constrained by stable core attributes such as species-specific sound repertoires and song syntax. To clarify whether similar constraints exist for song learning by humpbacks, we analyzed changes over 14 years in the sounds used by humpback whales singing in Hawaiian waters. We found that although the properties of individual sounds within songs are quite variable over time, the overall distribution of certain acoustic features within the repertoire appears to be stable. In particular, our findings suggest that species-specific constraints on temporal features of song sounds determine song form, whereas spectral variability allows whales to flexibly adapt song elements.

Acoustics↗
PubMed2006

Information entropy of humpback whale songs.

The structure of humpback whale (Megaptera novaeangliae) songs was examined using information theory techniques. The song is an ordered sequence of individual sound elements separated by gaps of silence. Song samples were converted into sequences of discrete symbols by both human and automated classifiers. This paper analyzes the song structure in these symbol sequences using information entropy estimators and autocorrelation estimators. Both parametric and nonparametric entropy estimators are applied to the symbol sequences representing the songs. The results provide quantitative evidence consistent with the hierarchical structure proposed for these songs by Payne and McVay [Science 173, 587-597 (1971)]. Specifically, this analysis demonstrates that: (1) There is a strong structural constraint, or syntax, in the generation of the songs, and (2) the structural constraints exhibit periodicities with periods of 6-8 and 180-400 units. This implies that no empirical Markov model is capable of representing the songs' structure. The results are robust to the choice of either human or automated song-to-symbol classifiers. In addition, the entropy estimates indicate that the maximum amount of information that could be communicated by the sequence of sounds made is less than 1 bit per second.

Acoustics↗
PubMed1994

Hierarchical structure of mitochondrial DNA gene flow among humpback whales Megaptera novaeangliae, world-wide.

The genetic structure of humpback whale populations and subpopulation divisions is described by restriction fragment length analysis of the mitochondrial (mt) DNA from samples of 230 whales collected by biopsy darting in 11 seasonal habitats representing six subpopulations, or 'stocks', world-wide. The hierarchical structure of mtDNA haplotype diversity among population subdivisions is described using the analysis of molecular variance (AMOVA) procedure, the analysis of gene identity, and the genealogical relationship of haplotypes as constructed by parsimony analysis and distance clustering. These analyses revealed: (i) significant partitioning of world-wide genetic variation among oceanic populations, among subpopulations or 'stocks' within oceanic populations and among seasonal habitats within stocks; (ii) fixed categorical segregation of haplotypes on the south-eastern Alaska and central California feeding grounds of the North Pacific; (iii) support for the division of the North Pacific population into a central stock which feeds in Alaska and winters in Hawaii, and an eastern or 'American' stock which feeds along the coast of California and winters near Mexico; (iv) evidence of genetic heterogeneity within the Gulf of Maine feeding grounds and among the sampled feeding and breeding grounds of the western North Atlantic; and (v) support for the historical division between the Group IV (Western Australia) and Group V (eastern Australia, New Zealand and Tonga) stocks in the Southern Oceans. Overall, our results demonstrate a striking degree of genetic structure both within and between oceanic populations of humpback whales, despite the nearly unlimited migratory potential of this species. We suggest that the humpback whale is a suitable demographic and genetic model for the management of less tractable species of baleen whales and for the general study of gene flow among long-lived, mobile vertebrates in the marine ecosystem.

Animals↗
PubMed2000

Acoustic interaction of humpback whales and whale-watching boats.

The underwater acoustic noise of five representative whale-watching boats used in the waters of west Maui was measured in order to study the effects of boat noise on humpback whales. The first set of measurements were performed on 9 and 10 March, close to the peak of the whale season. The ambient noise was relatively high with the major contribution from many chorusing humpback whales. Measurements of boat sounds were contaminated by this high ambient background noise. A second set of measurements was performed on 28 and 29 April, towards the end of the humpback whale season. In both sets of measurements, two of the boats were inflatables with outboard engines, two were larger coastal boats with twin inboard diesel engines and the fifth was a small water plane area twin hull (SWATH) ship with inter-island cruise capabilities. The inflatable boats with outboard engines produced very complex sounds with many bands of tonal-like components. The boats with inboard engines produced less intense sounds with fewer tonal bands. One-third octave band measurements of ambient noise measured on 9 March indicated a maximum sound pressure level of about 123 dB re 1 microPa at 315 Hz. The maximum sound pressure level of 127 dB at 315 Hz was measured for the SWATH ship. One of the boats with outboard engines produced sounds between 2 and 4 kHz that were about 8-10 dB greater than the level of background humpback whale sounds at the peak of the whale season. We concluded that it is unlikely that the levels of sounds produced by the boats in our study would have any grave effects on the auditory system of humpback whales.

Acoustics↗
PubMed1996

Populations genetic analysis of nuclear and mitochondrial loci in skin biopsies collected from central and northeastern North Atlantic humpback whales (Megaptera novaeangliae): population identity and migratory destinations.

It has been speculated that humpback whales, Megaptera novaeangliae, from the northeastern North Atlantic breed in tropical waters off the coast of West Africa and therefore that they represent a separate breeding population from that which winters in the West Indies. We determined the genotype at six microsatellite loci as well as the sequence of the first 288 nucleotides in the mitochondrial control region of 133 skin biopsies collected from humpback whales in the central North Atlantic (Iceland and Jan Mayen) and the northeastern North Atlantic (Bear Island and the northern coast of Norway). We detected no significant deviations from Hardy-Weinberg proportions nor any differences in genotype frequencies between localities at the nuclear loci. However, the mitochondrial analyses revealed two distinct matrilineal aggregations: the central and the northeastern North Atlantic. Our findings were not compatible with the idea of a separate eastern North Atlantic breeding ground unless one has been established recently. The proposed alternative hypothesis of a common North Atlantic panmictic population (wintering primarily in the West Indies) in which individual whales display maternally directed site-fidelity to specific feeding grounds was supported by re-sightings of two northeastern North Atlantic humpback whales in the West Indies.

Animals↗
PubMed1993

Abundant mitochondrial DNA variation and world-wide population structure in humpback whales.

Hunting during the last 200 years reduced many populations of mysticete whales to near extinction. To evaluate potential genetic bottlenecks in these exploited populations, we examined mitochondrial DNA control region sequences from 90 individual humpback whales (Megaptera novaeangliae) representing six subpopulations in three ocean basins. Comparisons of relative nucleotide and nucleotype diversity reveal an abundance of genetic variation in all but one of the oceanic subpopulations. Phylogenetic reconstruction of nucleotypes and analysis of maternal gene flow show that current genetic variation is not due to postexploitation migration between oceans but is a relic of past population variability. Calibration of the rate of control region evolution across three families of whales suggests that existing humpback whale lineages are of ancient origin. Preservation of preexploitation variation in humpback whales may be attributed to their long life-span and overlapping generations and to an effective, though perhaps not timely, international prohibition against hunting.

Animals↗
PubMed2004

Acoustic monitoring on a humpback whale (Megaptera novaeangliae) feeding ground shows continual singing into late Spring.

Singing by males is a major feature of the mating system of humpback whales, Megaptera novaeangliae (Borowski). Although a few songs have been opportunistically recorded on the whales' high-latitude feeding grounds, singing in these regions was thought to be only sporadic. We report results from the first continuous acoustic monitoring of a humpback whale feeding ground (off Cape Cod, MA, USA) in spring. Using autonomous sea-floor recording systems, we found singing on a daily basis over the entire 25 day monitoring period, from 14 May to 7 June 2000. For much of the period, song was recorded 24 h per day. These results, combined with evidence for aseasonal conceptions in whaling catch data, suggest that the humpback whale breeding season should no longer be considered as confined to lower-latitude regions in winter. Rather, we suggest breeding extends geographically and temporally onto feeding grounds into at least spring and early summer. Singing at these times represents either low-cost opportunistic advertising by (perhaps relatively few) males to court females that failed to conceive during the winter, and/or possibly an intrasexual display.

Animals↗
PubMed2006

The influence of maternal lineages on social affiliations among humpback whales (Megaptera novaeangliae) on their feeding grounds in the southern gulf of Maine.

Humpback whales on their feeding grounds in the Gulf of Maine typically form fluid fission/fusion groups of two to three individuals characterized by noncompetitive and, at times, cooperative behavior. Here we test the hypothesis that, despite the apparent absence of close kinship bonds, the fluid associations between feeding whales are influenced by "maternal lineages" as represented by mtDNA haplotypes. Using skin samples collected with a biopsy dart, variation in the hypervariable segment of the mtDNA control region identified 17 unique haplotypes among 159 individually identified whales from the southern Gulf of Maine. The haplotypes of a further 143 individuals were inferred from known direct maternal (cow-calf) relationships. The frequencies of associations among these 302 individuals were calculated from 21,617 sighting records collected from 1980 to 1995, excluding associations between a cow and her dependent calf. For groups of two where the haplotypes of both individuals were known (n = 3,151), individuals with the same haplotype were together significantly more often (26%) than expected by random association (20%). To account for different group sizes and associations with individuals of unknown haplotype and sex, we used Monte Carlo simulations to test for nonrandom associations in the full data set, as well as known female-only (n = 1,512), male-only (n = 730), and mixed-sex (n = 2,745) groups. Within-haplotype associations were significantly more frequent than expected at random for all groups (P = .002) and female-only groups (P = .011) but not male-only groups, while mixed-sex groups approached significance (P = .062). A Mantel test of individual pairwise association indices and haplotype identity confirmed that within-haplotype associations were more frequent than expected for all sex combinations except male-male associations, with females forming within-haplotype associations 1.7 times more often than expected by random assortment. Partial matrix correlations and permutation analyses indicated that the skew toward within-haplotype associations could not be accounted for by short-term temporal co-occurrence or fine-scale spatial distributions of individuals with shared haplotypes. While the mechanism by which individuals with a common mtDNA haplotype assort remains unknown, our results strongly suggest an influence of maternal lineages on the social organization of humpback whales within a regional feeding ground.

Animals↗
PubMed1997

Molecular analysis of paternity shows promiscuous mating in female humpback whales (Megaptera novaeangliae, Borowski).

It is widely assumed that the mating system of the humpback whale. Magaptera novaeangliae, is similar to that of most mammals in that it represents some form of polygyny or promiscuity, but this cannot be tested without observations of copulation or data on paternity of offspring. Microsatellite DNA markers were used to examine the paternity of calves born to individually identified mature female humpback whales from the Gulf of Maine. Skin biopsies were obtained from three females, and several (range: three to five) of their known offspring. Multiple paternity of offspring, indicated by the presence of at least three different paternal alleles, was evident in all three females at either three or four of the six microsatellite loci surveyed. Such promiscuous mating is expected given current knowledge of the social ecology of this species. It is also consistent with resightings of individually identified female humpbacks with different male associates during two or more breeding seasons.

Animals↗