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.     

Mitochondrial DNA diversity and population structure among southern right whales (Eubalaena australis)

The population structure and mitochondrial (mt) DNA diversity of southern right whales (Eubalaena australis) are described from 146 individuals sampled on 4 winter calving grounds (Argentina, South Africa, Western Australia, and the New Zealand sub-Antarctic) and 2 summer feeding grounds (South Georgia and south of Western Australia). Based on a consensus region of 275 base pairs of the mtDNA control region, 37 variable sites defined 37 unique haplotypes, of which only one was shared between regional samples of the Indo-Pacific and South Atlantic Oceans. Phylogenetic reconstruction of the southern right whale haplotypes revealed 2 distinct clades that differed significantly in frequencies between oceans. An analysis of molecular variance confirmed significant overall differentiation among the 4 calving grounds at both the haplotype and the nucleotype levels (F(ST) = 0.159; Phi(ST) = 0.238; P < 0.001). Haplotype diversity was significantly lower in the Indo-Pacific (h = 0.701 +/- 0.037) compared with the South Atlantic (h = 0.948 +/- 0.013), despite a longer history of exploitation and larger catches in the South Atlantic. In fact, the haplotype diversity in the Indo-Pacific basin was similar to that of the North Atlantic right whale that currently numbers about 300 animals. Multidimensional scaling of genetic differentiation suggests that gene flow occurred primarily between adjacent calving grounds within an ocean basin, with mixing of lineages from different calving grounds occurring on feeding grounds.     

Evaluating the effects of historic bottleneck events: an assessment of microsatellite variability in the endangered,North Atlantic right whale

Commercial exploitation reduced the North Atlantic right whale (Eubalaena glacialis) population from c. 12,000 in the 11th century to around 300 by the 21st century. We examine the effect of this population decline on levels of genetic variation at 16 microsatellite loci and contrast levels of variability to that in a closely related species (E. australis). Of the 13 loci developed from the E. glacialis genome, 100% were polymorphic in E. australis. In contrast, nine loci were polymorphic in E. glacialis and four were fixed. Both allelic diversity (A) and heterozygosity (H) were significantly lower in E. glacialis than E. australis (A = 3.2 +/- 2.6 vs. A= 6.9 +/- 3.3, P < 0.001; H= 0.31 +/- 0.25 vs. H= 0.72 +/- 0.23, P < 0.001, respectively). Bottleneck anlayses indicate that the population is in mutation-drift equilibrium and that a genetic bottleneck did not occur during the most recent decline (18th-20th centuries). Nevertheless, low frequency alleles are relatively uncommon in E. glacialis, suggesting that genetic variability has been reduced in this population. Possible origins of low genetic variability are discussed, including the slow but continual erosion of alleles during the 800-year period of decline.     

SEXUAL COMPOSITION and ANALYSIS OF REPRODUCTIVE FEMALES IN THE NORTH ATLANTIC RIGHT WHALE, EUBALAENA GLACIALIS, POPULATION

To test hypotheses involving reproduction and demographics, the sex of individuals must be established, but many species of Cetacea are not obviously dimorphic. In the North Atlantic right whale, Eubalaena glacialis , population, the sex of 61 males and 55 females had been determined previously by observation of the urogenital region, and the sex of 43 more females had been inferred from repeated sightings with a calf. To confirm the sex of some of these animals and to identify the sex of mote animals, genomic DNA was isolated from skin samples of 95 individual right whales (54 from among those described above and 41 additional recognizable individuals). The DNA was surveyed using the human Y-chromosome probe pDP1007. With Eco RI-digested DNA, a clear, sex-discriminating banding pattern was apparent. This method verified the sex of all 54 animals whose sex was previously known or inferred and identified the sex of an additional 41 recognizable individuals. A total of 89 male and 111 female right whales was identified in the population. The most unbiased estimate of sex ratio available is the 36 male and 34 female calves identified by genital morphology and DNA techniques. The sex ratio of this sample does not differ significantly from unity (P = 0.811). Only 38% (58/152) of the females in the North Atlantic population are known to have been reproductively successful compared with 54% in the population of right whales in the western South Atlantic. The population growth rate reported for the North Atlantic population is only 33% of that reported for right whales in the South Atlantic. Thirteen adult North Atlantic females have been identified that have not been known to calve during the past 11 yr. These data suggest that the absence of measurable recovery may be due to a combination of fewer actively reproducing females and lower reproductive rates of some females.     

Population histories of right whales (Cetacea: Eubalaena) inferred from mitochondrial sequence diversities and divergences of their whale lice (Amphipoda: Cyamus)

Right whales carry large populations of three 'whale lice' (Cyamus ovalis, Cyamus gracilis, Cyamus erraticus) that have no other hosts. We used sequence variation in the mitochondrial COI gene to ask (i) whether cyamid population structures might reveal associations among right whale individuals and subpopulations, (ii) whether the divergences of the three nominally conspecific cyamid species on North Atlantic, North Pacific, and southern right whales (Eubalaena glacialis, Eubalaena japonica, Eubalaena australis) might indicate their times of separation, and (iii) whether the shapes of cyamid gene trees might contain information about changes in the population sizes of right whales. We found high levels of nucleotide diversity but almost no population structure within oceans, indicating large effective population sizes and high rates of transfer between whales and subpopulations. North Atlantic and Southern Ocean populations of all three species are reciprocally monophyletic, and North Pacific C. erraticus is well separated from North Atlantic and southern C. erraticus. Mitochondrial clock calibrations suggest that these divergences occurred around 6 million years ago (Ma), and that the Eubalaena mitochondrial clock is very slow. North Pacific C. ovalis forms a clade inside the southern C. ovalis gene tree, implying that at least one right whale has crossed the equator in the Pacific Ocean within the last 1-2 million years (Myr). Low-frequency polymorphisms are more common than expected under neutrality for populations of constant size, but there is no obvious signal of rapid, interspecifically congruent expansion of the kind that would be expected if North Atlantic or southern right whales had experienced a prolonged population bottleneck within the last 0.5 Myr.     

DNA profile of a sixteenth century western North Atlantic right whale (Eubalaena glacialis)

Low levels of genetic variability identified within the North Atlantic right whale (Eubalaena glacialis), when compared to the Southern right whale (E. australis) and other large whales, have been suggested to result from population reductions due to whaling. Previous genetic analysis of 218 whale bones from sixteenth century Basque whaling sites in the western North Atlantic revealed only a single right whale bone. We determined the genotypes of 27 microsatellite loci using DNA isolated from this bone. All alleles from the historic specimen occur in the extant western North Atlantic population and both the probability of identity of the specimen and the number of heterozygous loci are similar to that in the extant population. Assessments of how genetically different the historical population might have been suggest genetic characteristics have not changed substantially over four centuries of whaling.     

Determination of steroid hormones in whale blow: It is possible

The feasibility of using analysis of hormone content of whale blow samples to assess reproductive function is addressed. A suitable collection method and analytical technique using liquid chromatography-mass spectrometry (LC-MS) has been developed. Blow samples were collected opportunistically from free-ranging humpback whales ( Megaptera novaeangliae ) ( n = 35) and North Atlantic right whales ( Eubalaena glacialis ) ( n = 18) using a 13-m carbon fiber pole with a collection device. Samples were analyzed for the presence of testosterone and progesterone using a 55% isocratic gradient with LC-MS. Testosterone was detected in four humpback whale samples and eight northern right whale samples. Progesterone was detected in seven humpback whale samples and eight northern right whale samples. This is the first documented use of lung mucosa to determine the presence of reproductive hormones in any free-swimming cetacean and may provide a novel non-invasive technique to quantify the hormonal condition of free-swimming animals that spend brief periods of time at the water's surface.     

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.     

G-banded karyotype and ideogram for the North Atlantic right whale (Eubalaena glacialis)

Published cytogenetic data for extant cetacean species remain incomplete. In a review of the literature, we found karyotypic information for 6 of the 13 tentatively recognized species of the suborder Mysticeti (baleen whales). Among those yet to be described is the critically endangered North Atlantic right whale (Eubalaena glacialis). Herein, we describe and propose a first-generation G-banded karyotype and ideogram for this species (2n = 42), obtained from peripheral blood chromosome preparations from a stranded male calf. This information may prove useful for future genetic mapping projects and for interspecific and intraspecific genomic comparisons by techniques such as zoo-FISH.     

Population structure and possible migratory links of common minke whales, Balaenoptera acutorostrata, in the Southern Hemisphere

Mitochondrial DNA control region sequences were analyzed to investigate population structure and possible migratory links of common minke whales (Balaenoptera acutorostrata) in two ocean basins: western South Atlantic (WSA) and western South Pacific (WSP). The results of several different phylogenetic estimations consistently grouped all haplotypes but one (n = 1) from these two ocean basins into two separate clades. South and North Atlantic haplotypes were more closely related to each other than either was to haplotypes from the WSP. The interpopulation genetic distance between WSA and WSP whales was similar to that reported between North Pacific and North Atlantic common minke whales (0.0234). The migration rate between the two ocean basins was estimated at near-zero using MDIV. The genetic evidence presented here was consistent with the hypothesis of migratory links among Brazil, Chilean Patagonia and the Antarctic Peninsula, and between low-latitude and Antarctic waters of the WSP. The results suggest multiple populations of common minke whales in the Southern Hemisphere, which may have conservation as well as taxonomic implications. Our single locus results should be corroborated by additional analyses in a larger number of samples and at more genetic markers.     

RIGHT WHALES (EUBALAENA GLACIALIS) ON JEFFREYS LEDGE: A HABITAT OF UNRECOGNIZED IMPORTANCE?

North Atlantic right whales ( Eubalaena glacialis ) are known to spend the majority of the year between the Great South Channel southeast of Cape Cod, and the Nova Scotian shelf. We examined sightings of right whales on and around Jeffreys Ledge, a 54-km-long glacial deposit off the coast of northern Massachusetts, New Hampshire, and Maine. Sightings on Jeffreys Ledge were extracted from three data sets: (1) a systematic survey of the entire northeastern continental shelf between 1979 and 1982, (2) whale-watch and research-cruise sighting data from 1984 to 1997, and (3) a collaborative database of sightings collected by organizations conducting right whale research and all other available sources. Each database supported two seasonal sighting peaks. During summer (especially July and August) sightings were primarily of mother-calf pairs. Several cow-calf pairs were seen over several days to weeks. Several females were resighted in more than one year, but only when calves were present. During October, November, and December, sightings included all age classes, surface-feeding behavior was frequently observed, and some animals were resighted over several weeks. Given the relatively reduced sighting effort during fall, this number of sightings is surprising. During the 20 yr of observations, 52 of 374 photo-identified North Atlantic right whales (13.9%) were seen at least once on Jeffreys Ledge. We suggest that Jeffreys Ledge may be a more important right whale habitat than previously believed, and that it may play an important role in annual movements and distribution of this population.     

Characterization of tetranucleotide microsatellite loci and development and validation of multiplex reactions for the study of right whale species (genus Eubalaena)

A North Atlantic right whale (Eubalaena glacialis) genomic library was developed and screened with a (GATA)₈ probe to identify tetranucleotide microsatellite loci. Sixteen characterized loci were polymorphic in North Atlantic and/or South Atlantic (Eubalaena australis) right whales, 12 being polymorphic in E. glacialis, and 15 in E. australis. Fourteen of these were combined with 21 other previously identified loci for a suite of 35 loci which can be used to increase resolution of genetic analyses of these species. Multiplex reactions were developed for genotyping samples at these loci, providing a method that is rapid, reliable and cost‐effective.     

Confirmation of right whales near a nineteenth-century whaling ground east of southern Greenland

North Atlantic right whales (Eubalaena glacialis) were found in an important nineteenth century whaling area east of southern Greenland, from which they were once thought to have been extirpated. In 2007-2008, a 1-year passive acoustic survey was conducted at five sites in and near the 'Cape Farewell Ground', the former whaling ground. Over 2000 right whale calls were recorded at these sites, primarily during July-November. Most calls were northwest of the historic ground, suggesting a broader range in this region than previously known. Geographical and temporal separation of calls confirms use of this area by multiple animals.     

LOCALIZATION OF NORTH ATLANTIC RIGHT WHALE SOUNDS IN THE BAY OF FUNDY USING A SONOBUOY ARRAY

A free-drifting 14-sonobuoy array was used to localize North Atlantic right whales ( Eubalaena glacialis ) in the Grand Manan Basin area of the Bay of Fundy. This area is a primary summer/autumn right whale habitat and overlaps an international shipping lane. The three-hour deployment on a single day provided two-dimensional localization of 94 right whale sounds based on arrival time differences determined from spectrogram cross-correlation analysis. The sounds were of two distinct types: tonal and gunshot. Maximum detection distances were about 30 km for both types of sound. The mean RMS location error was 1.8 km for tonal-type sounds and 2.5 km for gunshot-type sounds. The average RMS error was 20% of the average distance from the receiving hydrophones, the primary source of error being uncertainty in the sonobuoy positions.     

VESSEL COLLISIONS WITH WHALES: THE PROBABILITY OF LETHAL INJURY BASED ON VESSEL SPEED

Historical records demonstrate that the most numerous, per capita, ocean-going-vessel strikes recorded among large-whale species accrue to the North Atlantic right whale ( Eubalaena glacialis ). As vessel speed restrictions are being considered to reduce the likelihood and severity of vessel collisions with right whales, we present an analysis of the published historical records of vessels striking large whales. We examine the influence of vessel speed in contributing to either a lethal injury (defined as killed or severely injured) or a nonlethal injury (defined as minor or no apparent injury) to a large whale when struck. A logistic regression model fitted to the observations, and consistent with a bootstrap model, demonstrates that the greatest rate of change in the probability of a lethal injury ( P _lethal) to a large whale occurs between vessel speeds of 8.6 and 15 knots where P _lethal increases from 0.21 to 0.79. The probability of a lethal injury drops below 0.5 at 11.8 knots. Above 15 knots, P _lethal asymptotically approaches 1. The uncertainties in the logistic regression estimates are relatively large at relatively low speeds ( e.g. , at 8 knots the probability is 0.17 with a 95% CI of 0.03–0.6). The results we provide can be used to assess the utility of vessel speed limits that are being considered to reduce the lethality of vessels striking the critically endangered North Atlantic right whale and other large whales that are frequent victims of vessel strikes.     

Prevalence of Cryptosporidium spp. and Giardia spp. in five marine mammal species

Cryptosporidium spp. and Giardia spp. are protozoan parasites that are often associated with severe diarrheal disease in a variety of mammals. Although these parasites have been extensively studied in terrestrial ecosystems, little is known about either parasite in the marine environment. Therefore, the objective of this study was to determine the prevalence of both Cryptosporidium spp. and Giardia spp. in 5 marine mammal species. Fecal samples were collected from 39 bowhead whales (Balaena mysticetus), 49 North Atlantic right whales (Eubalaena glacialis), 31 ringed seals (Phoca hispida), 22 bearded seals (Erignathus barbatus), and 18 beluga whales (Delphinapterus leucas) between 1998 and 2003. Using an immunofluorescent assay, parasites were detected in the feces of bowhead whales, right whales, and ringed seals, while neither parasite was detected in samples from bearded seals or beluga whales. Overall, prevalences were highest in ringed seals (Cryptosporidium spp., 22.6%; Giardia spp., 64.5%) and right whales (Cryptosporidium spp., 24.5%; Giardia spp., 71.4%) and lowest in bowhead whales (Cryptosporidium spp., 5.1%; Giardia spp., 33.3%). To our knowledge, this is the first report of Cryptosporidium spp. and Giardia spp. in either whale species and of Cryptosporidium spp. in the ringed seal.     

Using pre- and postexploitation samples to assess the impact of commercial whaling on the genetic characteristics of eastern North Pacific gray and humpback whales and to compare methods used to infer historic demography

Many species of whales went through recent bottlenecks due to commercial whaling. These declines were rapid and recent relative to the life spans and generation times of these species, raising questions regarding to what degree commercial whaling influenced the genetic characteristics of these populations. We analyzed mitochondrial and nuclear DNA from pre- and postwhaling samples from two populations that have arguably shown the greatest degree of recovery: eastern North Pacific gray and humpback whales. We also compare the performance of different methods to test for historic bottlenecks and infer past demography based on genetic data. We found substantially higher levels of genetic diversity in gray than in humpback whales (for both time periods), likely due to recent connectivity between Atlantic and Pacific gray whale populations. Other than mitochondrial diversity in humpback whales, levels of diversity were not lower in contemporary samples relative to prewhaling samples, indicating that commercial whaling had a minimal impact on metrics of genetic diversity themselves. However, it did have large impacts on the patterns of diversity, as evidenced by all coalescent-based methods showing clear evidence of a bottleneck for both populations, whereas all but one method not based on the coalescent failed to detect a bottleneck.