Pseudorca Crassidens Research Articles

Stranding of a Newborn False Killer Whale on Utila Island, Honduras

Stranding of a Newborn False Killer Whale on Utila Island, Honduras

Novel Gammaherpesvirus Infections in Narrow-Ridged Finless Porpoise (Neophocaena asiaeorientalis) and False Killer Whales (Pseudorca crassidens) in the Republic of Korea.

A female narrow-ridged finless porpoise (Neophocaena asiaeorientalis) stranded on a beach on Jeju Island showed epithelial proliferative skin lesions on its body. Two false killer whales (Pseudorca crassidens), caught using nets near Gangneung and Samcheok, respectively, had multiple plaques on their penile epidermis. Histological examination of the epidermis revealed that all the lesions had common features, including accentuated rete pegs, ballooning changes, and eosinophilic intranuclear inclusion (INI) bodies. Based on the histopathological results, herpesvirus infection was suspected, and thus further analysis was conducted using herpesvirus-specific primers. Based on nested polymerase chain reaction (PCR) tests using the herpesvirus-detectable primers, the PCR products demonstrated two fragments: a 222-base-pair (bp) sequence of the DNA polymerase gene, SNUABM_CeHV01, showing 96.4% identity with a bottlenose dolphin herpesvirus from the Jeju narrow-ridged finless porpoise; and a 222 bp sequence of the DNA polymerase gene, SNUABM_CeHV02, showing 95.95% identity with the same bottlenose dolphin herpesvirus from the Gangneung and Samcheok false killer whales. The significance of this study lies in its ability to demonstrate the existence of novel cetacean herpesviruses in South Korean seawater, representing an important step forward in studying potentially harmful pathogens that affect endangered whale and dolphin populations.

Population structure and genetic diversity of false killer whales (Pseudorca crassidens) in New Zealand waters: preliminary results

ABSTRACT False killer whales (Pseudorca crassidens) are globally distributed cetaceans, often found in deep oceanic waters but occasionally near coastlines. Despite their broad distribution, information on their abundance, genetics, and ecology remains limited. In New Zealand waters, these whales occur year-round, with increased sightings during the warmer months due to the East Auckland Current. This study investigates the genetic diversity and population structure of New Zealand false killer whales using 17 samples collected from 2005 to 2018 in four locations, comparing them to global studies. New Zealand samples revealed four unique haplotypes with low genetic diversity (h = 0.42 ± 0.141; π = 0.29%± 0.002). No genetic differentiation was observed between South Pacific and New Zealand populations (FST = 0.05 p = 0.1602 Φ ST = 0.058 p = 0.145). These findings suggest low genetic diversity for New Zealand false killer whales, but within values expected for other cetaceans with matrilineal social structures. The presence of shared haplotypes suggests potential historical or ongoing connections with wider Pacific populations. However, further research is needed due to the short mtDNA-CR fragment analysed and small sample size, which may have resulted in an inability to capture the full extent of the genetic variation. This study contributes to our understanding of this species and its conservation within New Zealand.

Isotopic niches reveal the trophic structure of the cetacean community in the oceanic waters around the Azores

IntroductionThe oceanic waters around the Azores host a high diversity of cetaceans, with 28 species of toothed and baleen whales present year-round or seasonally. This high cetacean biodiversity likely plays an important role in the structure, functioning and productivity of the ecosystem, and may increase trophic redundancy, thus contributing to food web resilience to disturbances.MethodsHere we used stable isotope (δ13C and δ15N) analysis to characterize trophic niches, assess niche overlap, describe the trophic structure and discuss potential redundancy in the cetacean community. Using 407 samples from 12 species, we estimated Standard Ellipse Areas and overlaps between species and used a hierarchical clustering analysis to identify trophic guilds.Results and discussionδ13C and δ15N values ranged from -20.53 to -15.46‰ and from 7.78 to 14.41‰ respectively, suggesting the use of diverse habitats and resources among cetacean species. Clustering analysis revealed that species were grouped into four trophic guilds, segregated mainly by trophic position (TP): a low-TP guild with three zooplanktivore baleen whales, a mid-TP guild with micronektivores, a high-TP guild with micronekton and nekton consumers, and a cluster with only Pseudorca crassidens. There was significant isotopic niche overlap between one pair of species within each guild, indicating some potential for trophic redundancy in the community. Yet, these pairs also showed some form of spatial or temporal partitioning, suggesting that mechanisms promoting species coexistence could play a key role in structuring the cetacean community in the region and in its ecological role.

Ontogenetic changes in shape and growth rate during postnatal development in false killer whales (Pseudorca crassidens) vertebral column

AbstractIntraspecific variation in cetacean vertebral anatomy as a result of ageing, growth, and sexual dimorphism is poorly understood. Using 3D geometric morphometrics, we investigated allometric patterns, sexual dimorphism, and ontogenetic trajectories in the vertebral column of false killer whale (Pseudorca crassidens). Our data set includes thoracic, lumbar, and caudal vertebrae of 30 specimens, including neonates, juveniles, and adults of both sexes. Vertebral shape was significantly correlated with size within each region. Neonatal vertebral shape differed significantly from juveniles and adults, displaying ontogenetic shape change. Allometric and growth patterns of the vertebral regions, particularly of the lumbar region with the thoracic and caudal regions, differed significantly, which may influence the function and mobility patterns of the vertebral regions during different life stages. Using quantitative methods, we could not conclude that the Pseudorca vertebrae are sexually dimorphic. This study describes for the first time intraspecific vertebral patterns in a cetacean species across ontogenetic stages. Pseudorca individuals live in large pods and swim together, sharing the same swimming mode. The neonates have a more flexible column and swim less efficiently following their mothers to nurse.

False killer whales and fisheries in Hawaiian waters: evidence from mouthline and dorsal fin injuries reveal ongoing and repeated interactions

False killer whales and fisheries in Hawaiian waters: evidence from mouthline and dorsal fin injuries reveal ongoing and repeated interactions

First report of false killer whale Pseudorca crassidens in Bizerte, Tunisia

False killer whale (Pseudorca crassidens) is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found worldwide but mainly frequents tropical regions. This manuscript deals with the first sighting and stranding event recorded of the false killer whale in Mediterranean waters of Bizerte, northern Tunisia. The species has never been reported in the area despite years of collecting anecdotal and scientific information of cetaceans. This report extends previous knowledge of the false killer whale in the Mediterranean Sea.

A review of the effect of various type of artificial sounds to odontocetes

Reactions of bottlenose dolphins, Pacific white-sided dolphins, false killer whales, Risso's dolphins, Dall's porpoises to artificial underwater sounds were observed for developing countermeasures to reduce by-catch on gill nets. Related papers published during 1980-1995 in Japan were re-visited. Various sound projectors having dominant frequencies from 2 kHz to 200 kHz with source levels reaching up to 200dB re 1μPa. Reactions of dolphins and porpoises to the sounds were observed in a pool, a net enclosure, or an open sea. Clear escaping reactions from a sound source were observed by sounds with exposed level above 170dB at the subject animal. Reactions to sounds below 160dB were not stable. The dolphins got accustomed to the sound after multiple projections. On the other hand, frequency and amplitude modulated sounds seemed to be effective even if the sound pressure level was about 120dB. Efficacy of acoustic pingers to control wild dolphins and porpoises was limited. The exposure level to change behavior was estimated above 170dB that depends on the source level of a device and distance to the animal. Acclimation for the sounds by dolphins and porpoises were not negligible. Avoiding successive transmission and amplitude/frequency modulations induced behavioral reactions.

Dolphins from a prehistoric midden imply long-term philopatry of delphinids around Tokyo Bay

Abstract Cetaceans of the family Delphinidae are widely distributed throughout the global ocean, and it has been suggested that females exhibit philopatry. However, the duration of time that a maternal group of these highly mobile creatures spends inhabiting a particular region remains unknown. The objective of this study is to examine the genetic diversity of delphinids in the past and to shed light on the above question. In this study, we amplified and sequenced the mitochondrial DNA D-loop region from the skeletal remains of delphinids that were excavated from the Shomyoji Midden, a site situated on the western coast of Tokyo Bay and dating to 5000–3000 years before the present. We acquired prehistoric D-loop sequences of seven bottlenose dolphins, six Pacific white-sided dolphins, and a false killer whale. Notably, one or more haplotypes from the prehistoric individuals were detected in the geographically proximate modern conspecific populations across all three species. Whilst the genetic diversity of prehistoric and modern Pacific white-sided dolphin populations appears to be comparable, the modern bottlenose dolphin population demonstrates significantly lower genetic diversity when compared to its prehistoric counterpart in the vicinity of Tokyo Bay. The maternal groups of these species are speculated to have persisted in the same habitat for at least 4000 years.

First identification of stereotyped whistle contour types by Pseudorca crassidens

First identification of stereotyped whistle contour types by <i>Pseudorca crassidens</i>

Interspecies Retinal Diversity and Optic Nerve Anatomy in Odontocetes.

Throughout evolution, odontocete vision has had to readapt to the aquatic environment, which has had far-reaching effects on ocular anatomy and neurology. The most prominent features include the iris with an operculum, a well-developed choroid, the presence of giant ganglion cells in the retina, and the hemispherical shape of the thick eyecup. In the present study, the optic nerve and the retina were comparatively studied in Odontoceti (Cuvier's beaked whale, common bottlenose dolphin, false killer whale, long-finned pilot whale, Risso's dolphin, striped dolphin), the semi-aquatic common hippopotamus, and the fully terrestrial bovine. Cross-sections of the tissue were treated with histological and immunohistochemical techniques. Substantial differences were seen between the odontocetes and the reference species as well as within the cetaceans. The morphological structure of the optic nerve mainly appeared species specific, while the density of retinal ganglion cells was significantly higher in the terrestrial bovine than in the cetaceans. However, some typical characteristics of the cetacean retina were absent: the giant ganglion cells and the high retinal thickness. Immunohistochemical research showed varying degrees of neurofilament 200 expression in the retinal ganglion cells, while calretinin was only expressed in those of the common bottlenose dolphin and bovine.

False killer whales (Pseudorca crassidens Cetacea: Delphinidae) along the Pacific coast of Central America and Mexico: Long-term movements, association patterns and assessment of fishery interactions

Introduction: Worldwide, false killer whales (Pseudorca crassidens) are infrequently encountered, yet long-term studies have shown strong site fidelity as well as long-term associations among individuals in several locations. Detailed studies of this species have primarily been conducted around tropical oceanic islands or in the subtropical southern hemisphere.&#x0D; Objectives: We assess movements and association patterns among false killer whales along the Pacific coasts of the USA, Mexico, Guatemala, Nicaragua, Costa Rica including Isla del Coco, and Panama, representing one of the longest-running (albeit non-continuous) studies of this species. We also examine photos for evidence of interactions with fisheries, a known source of mortality to false killer whales.&#x0D; Methods: From Central America, we selected 212 individuals (50 encounter groups) out of 244 individuals (56 encounters) for inclusion in analyses based on photo quality and distinctiveness. Photos were collected on dedicated surveys from 1991-1994 and dedicated and opportunistic surveys from 1998-2022. Other than the effort off the oceanic Isla del Coco (1993-1994), surveys were undertaken in continental shelf waters. Additionally, we selected by photo quality and distinctiveness 124 (33 encounter groups) out of 189 individuals from southern California and Mexico for inclusion in these analyses. Association patterns were analyzed in SOCPROG and movements were analyzed in R.&#x0D; Results: Of the 328 total individuals, 158 (48.2 %) were encountered more than once, and 114 (34.8 %) were re-sighted after a year or more. The longest individual sighting history spanned 26.2 years with six re-sightings over that period between southern Costa Rica and Panama. Association and movement analyses revealed that individuals identified off southern Costa Rica and Panama linked into a single social network, with extensive movements between the two countries. Three individuals encountered off northern Costa Rica were re-sighted off northern Nicaragua, and individuals encountered off Nicaragua were encountered off Guatemala and central mainland Mexico. Nine matches were found among false killer whales between central mainland Mexico and Central America. There were no matches between the mainland coastal waters and the 33 individuals encountered around Isla del Coco. Dorsal fin disfigurements consistent with interactions with line fisheries ranged from 0 to 21 % for individuals within social clusters identified by community division.&#x0D; Conclusions: The infrequency of sightings combined with a high re-sighting rate of individuals and groups from the same area, suggests multiple small populations with large home ranges that include coastal waters. Small populations are sensitive to environmental changes, and as the human population grows, so do the demands on fisheries and ecotourism, which could directly impact the different populations. Additional effort in offshore areas is needed to determine the population status of false killer whales in pelagic waters, how often false killer whales using coastal waters move into pelagic waters, and the relationship between whales in the two habitats.

An automated approach for detection and classification of toothed whales in Hawai'i marine protected areas

Passive acoustic monitoring is an effective technique for studying cetacean presence within marine protected areas (MPAs). The Hawaiian archipelago is home to 18 species of resident toothed whales, but little is known regarding the spatio-temporal variability of false killer whales (Pseudorca crassidens—FKW) and short-finned pilot whales (Globicephala macrorhynchus) across Hawai‘i MPAs. Bottom-moored recorders were deployed inside and outside the Hawaiian Islands Humpback Whale National Marine Sanctuary and Papahānaumokuākea Marine National Monument through SanctSound and Pacific Islands Fisheries Science Center. High Frequency Acoustic Recording Packages (HARPs) and SoundTraps (200 kHz/48 kHz SR, respectively) deployed between 2018 and 2022, allowed leveraging of long-term datasets. Data used in this study include 27 deployments across 11 sites, encompassing &amp;gt;187 months of data. Here, we describe an automated approach for species classification which is challenging given the high spectral overlap in whistle features and acoustic masking during humpback whale season. PAMGuard detectors were used to detect whistles, clicks, and burst pulses. Features were extracted using PAMpal and species classified using BANTER models and confirmed from a Hawaiian Islands Ecosystem Assessment Survey annotated dataset. Acoustic monitoring provides vital information about the value of MPAs and a better understanding of endangered insular FKW habitat use.

The observation records from whale and dolphin watching inshore of Hualien, eastern Taiwan.

The eastern waters of Taiwan have been lacking baseline and research data for several years. This study was initiated by Kuroshio Ocean Education Foundation (KOEF) in collaboration with the Turumoan whale-watching company since 1998, collecting long-term ecological data for cetaceans in the inshore of Hualien, eastern Taiwan. This dataset includes 10,675 records of cetacean sightings from June 1998 to December 2021. Collection of cetacean sighting records was paused for one year in 2001 due to budgetary reasons. All of the sighting records were collected by whale-watching boat guides that were trained by KOEF. Following a standardised protocol, guides used a handheld GPS device and cetacean sighting record sheets to document information about the cetacean species identification, location, time, number of individuals, the presence of mother-calf pairs and mixed-species groups and other states of each sighting during a whale-watching tour. The collection of citizen-science data during this period has significantly advanced Taiwan's cetacean baseline data in the study area. Additionally, we make data available to the public in the form of citizen-science, making a substantial contribution to the advancement of ocean scientific research. We have published the dataset on Global Biodiversity Information Facility, allowing users around the world to download the dataset. This is currently the largest dataset of cetacean sighting records in Taiwan (last updated on 2023-09-05). We have also recorded several species on the International Union for Conservation of Nature (IUCN) Red List categorised as "Data Deficient" during our survey inshore of Hualien, eastern Taiwan, including Ginkgo-toothed beaked whales (Mesoplodonginkgodens Nishiwaki & Kamiya, 1958), Omura's whales (Balaenopteraomurai Wada, Oishi & Yamada, 2003) and killer whales (Orcinusorca (Linnaeus, 1758)). There are also sperm whales (Physetermacrocephalus Linnaeus, 1758), categorised as "Vulnerable" in the IUCN Red List and false killer whales (Pseudorcacrassidens (Owen, 1846)), categorised as "Near Threatened". This study is also the first and only long-term study that has documented cetaceans in the study area.

Frekuensi Pemunculan, Tingkah laku, dan Diversitas Cetacea di Perairan sekitar Labuan Bajo, Flores, Nusa Tenggara Timur

&#x0D; &#x0D; &#x0D; &#x0D; At least 30 cetaceans live in Indonesia, especially in the eastern waters of Indonesia, consisting of whales and dolphins. Cetaceans play an important role as a key species in determining the health of marine ecosystems. This study aims to determine the frequency of appearance, behavior, and diversity of cetaceans along Labuan Bajo, Flores, and East Nusa Tenggara. The study was conducted in October-November 2021, with four weeks to collect field data and interviews. The data involved a ship carrying a group of observers consisting of four people, with each task assigned to look for the appearance, species, and behavior of cetaceans. In the interview methods, interviews were conducted with fishermen regarding the presence of cetaceans. The data was then processed using the Microsoft Excel program and later plotted using the ArcView program as the outpour of the cetacean distribution. The results showed 19 occurrences of cetaceans, with six occurrences found in the field survey and 13 based on interviews with fishermen. Appearances were found to be evenly distributed in the study area, with a total of 7 species of cetaceans found, namely Stenella longirostris, Stenella attenuata, Tursiops truncates, Pseudorca crassidens, Grampus griseus, Kogia simus, and Physeter macrocephalus. In species composition and abundance, S. longirostris species had the highest value, and the P. crassidens species had the lowest composition value. A value of 1.06 was found in diversity, indicating that the cetaceans in Labuan Bajo were classified as moderate. Some behaviors include aerials, spy hopping, bow-riding, feeding, and avoidance.&#x0D; &#x0D; &#x0D; &#x0D;

Cetaceans playing with single-use plastics (SUPs): A widespread interaction with likely severe impacts

Play is a common behaviour in wild cetaceans that includes the manipulation of natural, as well as artificial objects such as marine debris. Yet, very little is known about these interactions despite the potential impacts on cetacean health. We combined a detailed review of the scientific literature and social media with 12 years of observations to examine cetacean interactions with plastic litter. A total of 11 odontocete species (Tursiops truncatus, Stenella longirostris, Delphinus delphis, Grampus griseus, Steno bredanensis, Stenella frontalis, Sotalia guianensis, Pseudorca crassidens, Orcinus orca, Globicephala melas and Physeter macrocephalus) were documented in 59 events carrying or throwing plastic litter with their head and/or flippers suggesting a form of play. Interactions occurred in the Atlantic, Pacific, Indian Ocean, Mediterranean, and Red Sea, with single-use plastics composing the main typology registered. While these interactions appeared harmless to the observers, they can pose a significant risk through subsequent entanglement or ingestion.

Ecological aspects of false killer whales (Pseudorca crassidens) from Mexican Pacific and Southern California waters

Ecological aspects of false killer whales (<i>Pseudorca crassidens</i>) from Mexican Pacific and Southern California waters

Identification of two novel papillomaviruses in belugas.

Papillomaviruses (PVs) can cause hyperplasia in the skin and mucous membranes of humans, mammals, and non-mammalian animals, and are a significant risk factor for cervical and genital cancers. Using next-generation sequencing (NGS), we identified two novel strains of papillomavirus, PV-HMU-1 and PV-HMU-2, in swabs taken from belugas (Delphinapterus leucas) at Polar Ocean Parks in Qingdao and Dalian. We amplified the complete genomes of both strains and screened ten belugas and one false killer whale (Pseudorca crassidens) for the late gene (L1) to determine the infection rate. In Qingdao, 50% of the two sampled belugas were infected with PV-HMU-1, while the false killer whale was negative. In Dalian, 71% of the eight sampled belugas were infected with PV-HMU-2. In their L1 genes, PV-HMU-1 and PV-HMU-2 showed 64.99 and 68.12% amino acid identity, respectively, with other members of Papillomaviridae. Phylogenetic analysis of combinatorial amino acid sequences revealed that PV-HMU-1 and PV-HMU-2 clustered with other known dolphin PVs but formed distinct branches. PVs carried by belugas were proposed as novel species under Firstpapillomavirinae. The discovery of these two novel PVs enhances our understanding of the genetic diversity of papillomaviruses and their impact on the beluga population.

Parturition and Nursing Events in a Cephalic Birth of a False Killer Whale (Pseudorca crassidens) in Managed Care

Parturition and Nursing Events in a Cephalic Birth of a False Killer Whale (Pseudorca crassidens) in Managed Care

Unusual occurrence of a mixed pod of false killer whales (Pseudorca crassidens) and common bottlenose dolphins (Tursiops truncatus) in the Beagle Channel (Argentina)

Unusual occurrence of a mixed pod of false killer whales (Pseudorca crassidens) and common bottlenose dolphins (Tursiops truncatus) in the Beagle Channel (Argentina)