Use of chemical tracers to assess diet and persistent organic pollutants in Antarctic Type C killer whales

Measuring chemical tracers in tissues of marine predators provides insight into the prey consumed and the predator's contaminant exposure. In this study, samples from Type C killer whales ( Orcinus orca ) biopsied in Antarctica were analyzed for chemical tracers ( i.e. , stable isotopes of carbon and nitrogen, fatty acids, and persistent organic pollutants [POPs]). Profiles of these individual tracers were very different from those of killer whale populations that have been studied in the eastern North and eastern Tropical Pacific. For example, δ¹³C and δ¹⁵N stable isotope values and most POP concentrations were significantly lower in the Antarctic population. In addition, multivariate statistical analyses of both fatty acid and POP profiles found distinctly different patterns for Antarctic Type C whales compared to those from whales in the other populations. Similar assays were conducted on four species of Antarctic marine fish considered potential prey for Type C killer whales. Results were consistent with a diet of fish for Type C whales, but other species ( e.g. , low trophic-level marine mammals or penguins) could not be eliminated as supplemental prey.     

Humpback whale (Megaptera novaeangliae) and killer whale (Orcinus orca) feeding aggregations for foraging on herring (Clupea harengus) in Northern Norway

Aggregations of predators on food patches have been documented for both terrestrial and marine animals. Here, we documented for the first time, and investigated, non-predatory aggregations occurring between humpback whales (Megaptera novaeangliae) and killer whales (Orcinus orca) while feeding on wintering Norwegian spring spawning herring (Clupea harengus) in Andfjord, northern Norway. Observational data were collected during 109 opportunistic surveys through three seasons 2013–2016. Killer whales were observed feeding on 59 occasions, with one to three humpback whales involved in 47 of these feeding events (79.7%), and there was an increased probability of finding feeding humpback whales when feeding killer whales also were observed. With killer whales identified as the initiating species in 94.4% of the feeding aggregations for which the first species was known, and with humpback whales joining and feeding on the fish ball afterwards, we suggest that humpback whales may benefit more from these aggregations than the opposite.     

Asymmetry of pectoral flipper use in the orca <Emphasis Type="Italic">Orcinus orca</Emphasis> (Linnaeus, 1758) from the Avachinskii Bay (Eastern Kamchatka)

Asymmetrical forelimb use is characteristic of many mammalian species. However, little is known about this phenomenon in cetaceans. We examined the asymmetry in pectoral flipper use by the wild orca Orcinus orca (Linnaeus, 1758). During observations from motor boats in the Avachinskii Bay (East Kamchatka) we recorded the use of flippers in slapping the water by individually identified resident (fish-eating) orcas. The studied individuals mostly used their right flipper. The revealed right-sided bias presumably reflects the pivotal role of the left brain hemisphere in the control of forelimb movements, which is consistent with the data that have been obtained for other cetacean species.     

FORAGING STRATEGIES OF SYMPATRIC KILLER WHALE (ORCINUS ORCA) POPULATIONS IN PRINCE WILLIAM SOUND, ALASKA

Killer whales ( Orcinus orca ) feed on a wide variety of fish, cephalopods, and marine mammals throughout their cosmopolitan range; however, the dietary breadth that characterizes the species is not reflected in all populations. Here, we present the findings of a 14-yr study of the diet and feeding habits of killer whales in Prince William Sound, Alaska. Two non-associating forms of killer whale, termed resident and transient (Bigg et al. 1987), were identified. All prey seen taken by transients were marine mammals, including harbor seals ( Phoca vitulina ), Dall's porpoises ( Phocoenoides dalli ), Steller sea lions ( Eumetopias jubatus ), and harbor porpoises ( Phocoena phocoena ). Resident killer whales appeared to prey principally on salmon ( Oncorhynchus spp.), preferring coho salmon ( O. kisutch ) over other, more abundant salmon species. Pacific herring ( Clupea pallasi ) and Pacific halibut ( Hippocampus stenolepis ) were also taken. Resident killer whales frequently were seen to interact in non-predatory ways with Steller sea lions and Dall's porpoises, while transients were not. Differences in the social organization and behavior of the resident and transient killer whales in Prince William Sound are discussed in the light of the dietary differences documented here.     

Spacing of wild schooling herring while encircled by killer whales

Herring (Clupea harengus) schools encircled by killer whales Orcinus orca and swimming under threat, show higher compaction than previous data on undisturbed herring but do not show maximum compaction as it would be predicted on theoretical grounds.     

Network scaling reveals consistent fractal pattern in hierarchical mammalian societies

Recent studies have demonstrated that human societies are hierarchically structured with a consistent scaling ratio across successive layers of the social network; each layer of the network is between three and four times the size of the preceding (smaller) grouping level. Here we show that similar relationships hold for four mammalian taxa living in multi-level social systems. For elephant (Loxodonta africana), gelada (Theropithecus gelada) and hamadryas (Papio hamadryas hamadryas) baboon, successive layers of social organization have a scaling ratio of almost exactly 3, indicating that such branching ratios may be a consistent feature of all hierarchically structured societies. Interestingly, the scaling ratio for orca (Orcinus orca) was 3.8, which might mean that aquatic environments place different constraints on the organization of social hierarchies. However, circumstantial evidence from a range of other species suggests that scaling ratios close to 3 may apply widely, even in species where hierarchical social structures have not traditionally been identified. These results identify the origin of the hierarchical, fractal-like organization of mammalian social systems as a fundamental question.     

Human Peak Experience Triggered by Encounters with Cetaceans

ABSTRACT

Although wild animals are listed in the literature of the humanistic sciences as a known peak trigger, this phenomenon has not until now been formally explored. In investigating peak experience from the perspective of the human—animal connection, the present study focuses on spontaneous encounters with cetaceans (whales and dolphins) that the human participant considered to be a highly significant personal event. Seven narrative stories were obtained from six human percipients who reported peak experience as a result of interactions with cetaceans which, with one exception, were free-ranging. The species represented are the Atlantic bottlenose dolphin (Tursiops truncatus); the orca (Orcinus orca), also known as killer whale or blackfish; and the beluga or white whale (Delphinapterus leucas). The data were analyzed through the process of phenomenological reduction, yielding five invariant themes: reciprocity of process, intention, connectedness, aliveness and harmony. Other essences of the wild-animal-triggered peak experience also are presented, along with suggestions regarding dynamics that may underlie spontaneous encounters which culminate in an emotional catharsis or other healing.     

Salmonella Newport omphaloarteritis in a stranded killer whale (Orcinus orca) neonate

Salmonella enterica serovar Newport (Salmonella Newport) was isolated from multiple tissues in a neonate killer whale (Orcinus orca) that stranded dead in 2005 along the central coast of California, USA. Necrotizing omphaloarteritis and omphalophlebitis was observed on histologic examination suggesting umbilical infection was the route of entry. Genetic analysis of skin samples indicated that the neonate had an offshore haplotype. Salmonellosis has rarely been identified in free-ranging marine mammals and the significance of Salmonella Newport infection to the health of free-ranging killer whales is currently unknown.     

Oschmarinella albamarina (Treshchev, 1968) n. comb., a liver fluke from the killer whale Orcinus orca (L.) off the British coast

Oschmarinella albamarina n. comb. is described from the bile-ducts of a killer whale Orcinus orca stranded on the British coast. The systematic position of the species is discussed in relation to the genera Campula Cobbold, 1858, Orthosplanchnus Odhner, 1905 and Oschmarinella Skrjabin, 1947, and the species is transferred from Orthosplanchnus to Oschmarinella. Campula rochebruni (Poirrier, 1886) is transferred to Oschmarinella, as O. rochebruni n. comb., and Oschmarinella mascomai Raga, 1986 is considered its synonym.     

Low worldwide genetic diversity in the killer whale (Orcinus orca): implications for demographic history

A low level of genetic variation in mammalian populations where the census population size is relatively large has been attributed to various factors, such as a naturally small effective population size, historical bottlenecks and social behaviour. The killer whale (Orcinus orca) is an abundant, highly social species with reduced genetic variation. We find no consistent geographical pattern of global diversity and no mtDNA variation within some regional populations. The regional lack of variation is likely to be due to the strict matrilineal expansion of local populations. The worldwide pattern and paucity of diversity may indicate a historical bottleneck as an additional factor.     

A century of Chinook salmon consumption by marine mammal predators in the Northeast Pacific Ocean

As many marine mammal populations have increased following bans on their harvest, there has been a growing need to understand potential impacts of these population changes on coastal marine ecosystems. Quantifying consumption of prey species, such as fish, is particularly important when those same prey are also targeted by commercial fisheries. Estimating the impact of marine mammal predators on prey fish depends upon knowledge of marine mammal diet composition; scientific advances over the last century have improved understanding of diets but have also led to inconsistent methods that challenge attempts at synthesis and comparison. Meta-analysis techniques offer the opportunity to overcome such challenges, yet have not been widely applied to synthesize marine mammal diets over space and time. As a case study, we focus on synthesizing diet studies of Chinook (king) salmon (Oncorhynchus tshawytscha) by four species of marine mammal predators in the Northeast Pacific Ocean: Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), harbor seals (Phoca vitulina), and killer whales (Orcinus orca). We also highlight several simple meta-analyses for which these types of diet databases may be employed. Our assembled database consists of > 330 records, spanning more than 100 years. Results indicate that the frequency of occurrence of Chinook salmon in killer whale studies is high (63%) relative to pinniped studies (< 10%). They also suggest a strong increasing ability to discriminate Chinook salmon from other salmonids, which we attribute to switches in diet studies from lethal or observational sampling toward molecular methods (DNA, fatty acids). Our database and analysis code are published as supplementary material, which we hope will be useful for other researchers and will inspire more of these syntheses.     

CETACEANS OF THE NORTHERN GULF OF CALIFORNIA: DISTRIBUTION, OCCURRENCE, and RELATIVE ABUNDANCE

A total of 1,715 km of boat-based surveys and 1,521 km of aircraft-based surveys was conducted from 1986–1989 to assess the distribution, relative abundance, and ecological relationships of cetaceans in the northern Gulf of California. Seven cetacean species were seen; in decreasing frequency of groups encountered they were: bottlenose dolphins, Tursiops truncatus ; vaquitas, Phocoena sinus ; common dolphins, Delphinus delphis ; fin whales, Balaenoptera physalus ; Bryde's whales, B. edeni ; gray whales, Eschrichtius robustus , and killer whales, Orcinus orca. Common dolphins were numerically dominant and bottlenose dolphins were seen most often. Bryde's whales and vaquitas had the smallest group sizes. In general, the odontocete cetaceans were separated spatially, whereas the distribution of Bryde's and fin whales overlapped considerably.     

Evidence of Helicobacter sp. in dental plaque of captive dolphins (Tursiops gephyreus)

Gastrointestinal lesions have been extensively reported in wild and captive marine mammals. However, their etiology remains unclear. In humans and other animals, chronic gastritis and peptic ulcers have been associated with Helicobacter sp. Therefore, the aim of our study was to investigate the presence of Helicobacter sp. in the gastric juice, dental plaque, and saliva of marine mammals living in a controlled environment. Five dolphins (Tursiops gephyreus), one killer whale (Orcinus orca), one false killer whale (Pseudorca crassidens), three sea lions (Otaria flavescens), two elephant seals (Mirounga leonina), and two fur seals (Arctocephalus australis) were studied. Saliva, dental plaque, and gastric juice samples were examined for Helicobacter sp. using polymerase chain reaction. None of the gastric juice or saliva samples were positive for Helicobacter sp. However, Helicobacter sp. DNA was detected in dental plaque from two dolphins, suggesting the oral cavity might be a reservoir of this bacterium.     

Nucleotide sequence of the D-loop region of the sperm whale (Physeter macrocephalus) mitochondrial genome

We have amplified, by the polymerase chain reaction, and have sequenced the D-loop region of the mitochondrial DNA from the sperm whale (Physeter macrocephalus). The sperm whale D-loop was aligned with D- loop sequences from four other cetaceans (Commerson's dolphin, orca, fin whale, and minke whale) and an out-group (cow). This alignment showed the sperm whale sequence to be larger than that of other cetaceans. In addition, some sequence blocks were highly conserved among all six species, suggesting roles in the functioning of mitochondrial DNA. Other blocks that were previously reported to be well conserved among cetaceans showed little sequence conservation with the sperm whale D-loop, which argues against the functional importance of these sequence blocks in cetaceans.      

Isolation of St. Louis encephalitis virus from a killer whale

We report the isolation of St. Louis Encephalitis (SLE) virus from a mature male killer whale (Orcinus orca). This represents the first isolation of SLE virus from a marine mammal. The animal presented with reduced appetite, rapidly became lethargic and subsequently died. Virus-induced CPE was observed in a dolphin cell line, SP-1K (ATCC CCL 78), inoculated with brain, kidney, and lung tissues obtained at necropsy. Electron microscopy of infected SP-1K cells revealed the presence of virions having morphology and size resembling members of the Flaviviridae. Final identification as SLE virus was made by neutralization and immunofluorescence staining tests.     

Killer whales are capable of vocal learning

The production learning of vocalizations by manipulation of the sound production organs to alter the physical structure of sound has been demonstrated in only a few mammals. In this natural experiment, we document the vocal behaviour of two juvenile killer whales, Orcinus orca, separated from their natal pods, which are the only cases of dispersal seen during the three decades of observation of their populations. We find mimicry of California sea lion (Zalophus californianus) barks, demonstrating the vocal production learning ability for one of the calves. We also find differences in call usage (compared to the natal pod) that may reflect the absence of a repertoire model from tutors or some unknown effect related to isolation or context.     

The influence of social affiliation on individual vocal signatures of northern resident killer whales (Orcinus orca)

Northern resident killer whales (Orcinus orca) live in highly stable groups and use group-specific vocal signals, but individual variation in calls has not been described previously. A towed beam-forming array was used to ascribe stereotyped pulsed calls with two independently modulated frequency contours to visually identified individual killer whales in Johnstone Strait, British Columbia. Overall, call similarity determined using neural networks differed significantly between different affiliation levels for both frequency components of all the call types analysed. This method distinguished calls from individuals within the same matriline better than different calls produced by a single individual and better than by chance. The calls of individuals from different matrilines were more distinctive than those within the same matriline, confirming previous studies based on group recordings. These results show that frequency contours of stereotyped calls differ among the individuals that are constantly associated with each other and use group-specific vocalizations, though across-group differences were substantially more pronounced.     

Inferred Paternity and Male Reproductive Success in a Killer Whale (Orcinus orca) Population

We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating ("resident") eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same "pod" (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was <30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck.     

The prevalence of Toxoplasma gondii antibodies in wild and captive cetaceans from Japan

The seroprevalence of Toxoplasma gondii was investigated in wild and captive cetaceans from Japan. Antibodies against T. gondii were examined by both latex agglutination test (LAT) and indirect hemagglutination test (IHAT) for 77 serum or plasma samples obtained from 59 individuals of 6 species, including 2 hybrids. Antibody titers greater than 1:64 in LAT and greater than 1:640 in IHAT, indicative of the presence of T. gondii, were found in 11.9% of 59 individuals. In 7 samples that showed a positive reaction by IHAT, T. gondii titers were examined for each immunoglobulin (Ig) fraction separated by sucrose gradient centrifugation. The antibody peaks in each fraction were divided into 3 types, thought to be a reaction of IgM (type 1), IgG (type 2), and IgM with IgG (type 3). Type 1 was found in serum from a bottle-nosed dolphin (Tursiops truncatus) and a killer whale (Orcinus orca) sampled soon after capture off the Japanese coast in 1988; it was concluded that infection in the wild had occurred less than 15 yr before the study was performed. The prevalence of putative IgM and IgG antibodies from a captive-bred T. truncatus suggested that T. gondii infection also occurred in the aquarium.     

VNTRseek—a computational tool to detect tandem repeat variants in high-throughput sequencing data

DNA tandem repeats (TRs) are ubiquitous genomic features which consist of two or more adjacent copies of an underlying pattern sequence. The copies may be identical or approximate. Variable number of tandem repeats or VNTRs are polymorphic TR loci in which the number of pattern copies is variable. In this paper we describe VNTRseek, our software for discovery of minisatellite VNTRs (pattern size ≥ 7 nucleotides) using whole genome sequencing data. VNTRseek maps sequencing reads to a set of reference TRs and then identifies putative VNTRs based on a discrepancy between the copy number of a reference and its mapped reads. VNTRseek was used to analyze the Watson and Khoisan genomes (454 technology) and two 1000 Genomes family trios (Illumina). In the Watson genome, we identified 752 VNTRs with pattern sizes ranging from 7 to 84 nt. In the Khoisan genome, we identified 2572 VNTRs with pattern sizes ranging from 7 to 105 nt. In the trios, we identified between 2660 and 3822 VNTRs per individual and found nearly 100% consistency with Mendelian inheritance. VNTRseek is, to the best of our knowledge, the first software for genome-wide detection of minisatellite VNTRs. It is available at http://orca.bu.edu/vntrseek/.