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Extremes in organismal size have broad interest in ecology and evolution because organismal size dictates many traits of an organisms biology. There is particular fascination with identifying upper size extremes in the largest vertebrates, given the challenges and difficulties of measuring extant and extinct candidates for the largest animal of all time, such as whales, terrestrial non-avian dinosaurs, and extinct marine reptiles. The discovery of Perucetus colossus, a giant basilosaurid whale from the Eocene of Peru, challenged many assumptions about organismal extremes based on reconstructions of its body weight that exceeded reported values for blue whales (Balaenoptera musculus). Here we present an examination of a series of factors and methodological approaches to assess reconstructing body weight in Perucetus, including: data sources from large extant cetaceans; fitting published body mass estimates to body outlines; testing the assumption of isometry between skeletal and body masses, even with extrapolation; examining the role of pachyostosis in body mass reconstructions; addressing method-dependent error rates; and comparing Perucetus with known physiological and ecological limits for living whales, and Eocene oceanic productivity. We conclude that Perucetus did not exceed the body mass of todays blue whales. Depending on assumptions and methods, we estimate that Perucetus weighed 60-70 tons assuming a length 17 m. We calculated larger estimates potentially as much as 98-114 tons at 20 m in length, which is far less than the direct records of blue whale weights, or the 270 ton estimates that we calculated for body weights of the largest blue whales measured by length.

The large, metabolically expensive brains of manta and devil rays (Mobula spp.) may act as a thermogenic organ representing a unique mechanistic basis for cranial endothermy among fishes that improves central nervous system function in cold waters. Whereas early hominids in hot terrestrial environments may have experienced a thermal constraint to evolving larger brain size, cetaceans and mobulids in cold marine waters may have experienced a thermal driver for enlargement of a thermogenic brain. The potential for brain enlargement to yield the dual outcomes of cranial endothermy and enhanced cognition in mobulids suggests one may be an evolutionary by‐product of selection for the mechanisms underlying the other, and highlights the need to account for non‐cognitive functions when translating brain size into cognitive capacity. Computational scientific imaging offers promising avenues for addressing the pressing mechanistic and phylogenetic questions needed to assess the theory that cranial endothermy in mobulids is the result of temperature‐driven selection for a brain with augmented thermogenic potential. [ABSTRACT FROM AUTHOR]

Plastic is a ubiquitous environmental contaminant, resulting in widespread exposure across terrestrial and marine spaces. In the environment, plastics can degrade into microparticles where exposure has been documented in a variety of fauna at all trophic levels. Human epidemiological studies have found relationships between inhaled microplastics and oxidative stress and inflammation. Previous studies of bottlenose dolphins (Tursiops truncatus) have reported prevalent exposure to plasticizing chemicals (e.g., phthalates) as well as particle loads in gastrointestinal tracts, but exposure from inhalation has not yet been studied. The objective of this study was to determine if inhalation is a viable route of microplastic exposure for free-ranging dolphins. Exhalation samples were opportunistically collected from dolphins residing in Sarasota Bay, Florida (n = 5) and Barataria Bay, Louisiana (n = 6) during catch-and-release health assessments to screen for microplastic particles. All dolphin samples contained at least one suspected microplastic particle, and polymer composition was determined for 100% of a subset (n = 17) of samples. Additional studies are warranted to better understand the extent of inhaled microplastics, as well as to explore impacts, given potential risks to lung function and health. [ABSTRACT FROM AUTHOR]

Rationale: Stable isotope analysis of bone provides insight into animal foraging and allows for ecological reconstructions over time, however pre‐treatment is required to isolate collagen. Pre‐treatments typically consist of demineralization to remove inorganic components and/or lipid extraction to remove fats, but these protocols can differentially affect stable carbon (δ13C) and nitrogen (δ15N) isotope values depending on the chemicals, tissues, and/or species involved. Species‐specific methodologies create a standard for comparability across studies and enhance understanding of collagen isolation from modern cetacean bone. Methods: Elemental analyzers coupled to isotope ratio mass spectrometers were used to measure the δ13C and δ15N values of powdered killer whale (Orcinus orca) bone that was intact (control) or subjected to one of three experimental conditions: demineralized, lipid‐extracted, and both demineralized and lipid‐extracted. Additionally, C:N ratios were evaluated as a proxy for collagen purity. Lastly, correlations were examined between control C:N ratios vs. historical age and control C:N ratios vs. sample characteristics. Results: No significant differences in the δ15N values were observed for any of the experimental protocols. However, the δ13C values were significantly increased by all three experimental protocols: demineralization, lipid extraction, and both treatments combined. The most influential protocol was both demineralization and lipid extraction. Measures of the C:N ratios were also significantly lowered by demineralization and both treatments combined, indicating the material was closer to pure collagen after the treatments. Collagen purity as indicated via C:N ratio was not correlated with historical age nor sample characteristics. Conclusions: If only the δ15N values from killer whale bone are of interest for analysis, no pre‐treatment seems necessary. If the δ13C values are of interest, samples should be both demineralized and lipid‐extracted. As historical age and specimen characteristics are not correlated with sample contamination, all samples can be treated equally. [ABSTRACT FROM AUTHOR]

This document is a compilation of references related to the outbreak of avian influenza, specifically the H5N1 strain, in different regions worldwide. It includes scientific articles, reports, and studies discussing the spread of the virus among wild birds, marine mammals, and other animals. The references also cover the impact of the virus on various species and ecosystems, as well as efforts to control and prevent its spread. Researchers and library patrons interested in studying the avian influenza outbreak and its effects on wildlife will find valuable information in these references. Additionally, the document includes references to topics such as marine mammal ecotoxicology, the conservation of Galápagos birds, the prevention and control of highly pathogenic avian influenza, and Ecuador's preparedness and response to the COVID-19 pandemic. [Extracted from the article]

Simple Summary: Photobacterium damselae subsp. damselae (Pdd) is a marine bacterium that can infect a variety of marine animals and humans. Although this bacterium has been isolated from several stranded dolphins and whales, its pathogenic role in cetaceans is still unclear and very limited information exists on its occurrence in these animals. In this study, we report data relating to the presence of Pdd in marine mammals stranded within the Liguria Pelagos Sanctuary from 2017 to 2022. Our findings show a 41.5% (22/53) Pdd prevalence in stranded cetaceans, where 22.7% (5/22) of these were positive in at least one of the Pdd virulence factors which, in previous studies, have been related to Pdd pathogenicity. Our results also revealed that in all cases where cetaceans tested positive for Pdd, other well-known pathogens for these species were also present. This finding supports the hypothesis that Pdd is an opportunistic agent that might contribute to the worsening of health conditions in subjects already compromised by other pathogens, contributing to their death. However, further studies are necessary to investigate and deepen this hypothesis. Photobacterium damselae subsp. damselae (Pdd) is an increasingly common bacterium in post-mortem diagnostics of beached marine mammals, but little is known about its precise etiological responsibility. To estimate the prevalence of Pdd in stranded cetaceans from 2017 to 2022 on the Ligurian coast (Pelagos Sanctuary), we tested tissues from 53 stranded individuals belonging to four cetacean species. DNA extracts from cetacean tissue were screened using a polymerase chain reaction (PCR) assay targeting the Pdd ureC gene. Positive samples were screened by PCR for dly, hlyApl and hlyAch hemolysin genes, which were confirmed by sequencing. Twenty-two out of 53 (41.5%) cetaceans analyzed by PCR were confirmed for Pdd DNA in at least one tissue among those analyzed. Five of these cetaceans were positive for at least one of the hemolysin genes tested. In all Pdd-positive cetaceans, other pathogens that were considered responsible for the causa mortis of the animals were also found. The results provide new information on the spread of Pdd in cetaceans and support the thesis that Pdd might be an opportunistic agent that could contribute to worsening health conditions in subjects already compromised by other pathogens. However, further studies are needed to investigate and deepen this hypothesis. [ABSTRACT FROM AUTHOR]

The Kekenodontidae are late-surviving archaeocetes from the Late Oligocene of Southwest Pacific that includes a single-named species, Kekenodon onamata. Tohoraonepu nihokaiwaiu is a new genus and species of small body-sized kekenodontid from the upper Oligocene (Chattian) Kokoamu Greensand of Otago, South Island, New Zealand. Phylogenetic analyses recover T. nihokaiwaiu within a monophyletic Kekenodontidae, forming a clade with an unnamed provisional kekenodontid, OU 22023. Kekenodontids are recovered crownward to basilosaurids and stemward to a paraphyletic group of toothed 'mysticetes' that are excluded from Neoceti. The analyses confirm the identification of kekenodontids as the latest-diverging archaeocetes that persisted into the Late Oligocene. The holotype OU 22394 is a juvenile individual preserving several isolated heterodont teeth with characteristics of deciduous teeth, including unmineralized pulp cavities and cheek teeth with lower-lying triangular crowns that are different from all known kekenodontids. Diphyodonty is known from Eocene archaeocetes but is unknown from geologically younger toothed cetaceans, with monophyodonty being hypothesised for all Neoceti. Inferences of diphyodonty in T. nihokaiwaiu would be the first instance in Cetacea from rocks geologically younger than the Eocene and would indicate diphyodonty persisted in some Late Oligocene archaeocetes. [ABSTRACT FROM AUTHOR]

The earliest Miocene (Aquitanian, 23–20 Ma) remains a critically under-sampled 'dark age' in cetacean evolution. This is especially true of baleen whales (mysticetes), Aquitanian specimens of which remain almost entirely unknown. Across the globe, the nature of the cetacean fossil record radically shifts at the Oligocene-Miocene boundary, with mysticetes and some archaic odontocete lineages suddenly disappearing despite the availability of cetacean-bearing rock units. New Zealand is the only place worldwide where this change is not readily apparent, with baleen whales apparently persisting into the earliest Miocene. Whether this is a genuine pattern has so far remained obscured by a lack of biostratigraphic resolution associated with the Oligo-Miocene boundary. Here, we report 23 new strontium (87Sr/86Sr) dates from Lentipecten shells associated with 16 mysticete and seven odontocete specimens, respectively. Of these, eight fall within the Early Miocene and seven – including five mysticetes – specifically within the Aquitanian. Our findings confirm the unique nature and global importance of the cetacean fossil record from New Zealand, and provide a foundation for investigations into the causes and effects of the Early Miocene cetacean 'dark age'. [ABSTRACT FROM AUTHOR]

Eomysticetidae are a clade of early diverging functionally toothless, longirostrine and likely baleen-bearing stem mysticete whales. Eomysticetid fossils are rare but known worldwide from Oligocene strata. The richest assemblage of eomysticetids has been uncovered in New Zealand from the Kokoamu Greensand and Otekaike Limestone (North Otago and South Canterbury regions, South Island). This includes some of the largest known eomysticetids, Tokarahia kauaeroa and Tokarahia lophocephalus, some older and more archaic forms such as Matapanui waihao, the fragmentary Tohoraata raekohao and Tohoraata waitakiensis, and the well-known Waharoa ruwhenua represented by several well-preserved skulls and mandibles of adults and juveniles. Studies of these New Zealand fossils strongly indicates monophyly of Eomysticetidae and suggest possible skim feeding behaviour, possession of non-functional teeth and baleen, extreme rostral lengthening during growth and peramorphic evolution, rostral kinesis, use of Zealandia as a calving ground, and probable extinction at or near the Oligo-Miocene boundary. [ABSTRACT FROM AUTHOR]

The Irrawaddy dolphin (Orcaella brevirostris) is an endangered cetacean that ranges throughout much of Southeast Asia and lives in coastal, estuarine, and riverine habitats including three river systems: Ayeyarwady, Mekong, and Mahakam. Many populations face risks from human interference, but overall rangewide diversity and connectivity is not well‐understood. Here we sequenced 77 complete mitogenomes from across the range of the Irrawaddy dolphin including all obligate riverine populations; eighteen of these were sequenced from historical museum specimens. Phylogenetic analysis showed haplotypes from each riverine population formed separate clades nested within the wider species implying each river system was separately invaded only once. All Irrawaddy dolphin mitogenomes were dated to a last common ancestor ~764 kya. Most lineages appeared after inundation cycles of the Sunda Shelf were initiated ~400 kya. Despite the lack of monophyly among many haplotypes from the same population, no population shared any haplotypes. Rangewide nucleotide diversity was average compared to other odontocetes, but riverine populations were especially low. Differentiation was significant among all populations analyzed with the most divergence occurring between isolated riverine populations. These analyses add more evidence for the necessity of conservation efforts directed towards riverine and other isolated populations of the Irrawaddy dolphin. [ABSTRACT FROM AUTHOR]

Understanding the activity budget of mother‐young pairs can inform how energy is allocated and its relation to the development of young. Using suction cup tag data collected off Sainte Marie, Madagascar, during the calving season, we compared the time budgets of mothers and their calves in capital‐breeding humpback whales, investigated the changes with age, and assessed mother‐calf behavioral synchrony based on their swimming speed. We found that mothers and calves allocated much of their time to low‐level activities (i.e., static/quasi‐static or swimming at low speed). Young calves engaged more in slow swimming than older calves and mothers. Mothers with younger calves tended to stay static or quasi‐static less than mothers with older ones. Calves displayed some degree of independence in activities but were also observed synchronizing their activities with their mothers. Depending on the nature of the activity, the initiation of it was driven by either the calf or the mother. Our study provides additional knowledge for understanding the behavioral dynamics and interactions within humpback whale mother‐calf pairs. It provides data that can support the implementation of conservation measures. [ABSTRACT FROM AUTHOR]

Kekenodontids are the only known archaeocetes (stem cetaceans) from the late Oligocene. They possess a unique combination of morphological features seen in both more primitive Eocene basilosaurid archaeocetes and more derived Neoceti (mysticetes and odontocetes). However, much remains unknown about the clade, including its acoustic biology. Based on its phylogenetic position crownward to basilosaurids as the latest‐diverging archaeocete, we hypothesize that kekenodontids would be specialized for hearing low‐frequency sounds. Here, we provide the first report on the cochlear anatomy of a kekenodontid using the holotype of Kekenodon onamata from New Zealand. We compare the cochlear morphology of K. onamata to a sample of extinct and extant cetaceans and quantify shape differences using three‐dimensional geometric morphometrics. The analyses show that K. onamata was indeed adapted to hear low frequencies and suggests low‐frequency hearing may be a characteristic of raptorial macrophagous fossil cetaceans in contrast to infrasonic bulk filter‐feeding mysticetes and ultrasonic echolocating odontocetes. [ABSTRACT FROM AUTHOR]

Hitherto unreported whale fall fauna has been found from the Lower Miocene of Khari Nadi Formation of Kutch, India.This vertebrate-invertebrate assemblage comprises jumbled up bone fragments of different parts of the whale along with molluscs and echinoids. Some representatives in this assemblage are characteristic whale fall fauna and some are characteristic shallow marine fauna. The molluscs belong to the families Buccinidae, Provannidae, Naticidae, Turritellidae, Borsoniidae, Volutidae, Haminoeidae, Cypraeidae, Strombidae, Rostelleriidae, Cassidae, Osteridae, Veneridae, Astartidae and the echinoids to family Spatangidae and Schizasteridae. The present study reveals that the deposition of this entire assemblage was in a shallow marine environment and also sheds some light on the molluscan association related to a whale fall from the western Indian sea waters in the Lower Miocene. [ABSTRACT FROM AUTHOR]

Introduction: Whales, dolphins, and porpoises are susceptible to infections by protozoan and metazoan parasites. Methods: In this study, tissue samples, as well as flatworms and roundworms, were collected from a common bottlenose dolphin (Tursiops truncatus), three short-beaked common dolphins (Delphinus delphis), two striped dolphins (Stenella coeruleoalba), a harbor porpoise (Phocoena phocoena), a long-finned pilot whale (Globicephala melas), and a fin whale (Balaenoptera physalus). These samples were molecularly analyzed. Results: In one D. delphis, Toxoplasma gondii was detected in multiple organs, including the cerebellum. The cysts of the tapeworms Clistobothrium delphini and Clistobothrium grimaldii were identified in G. melas. Flukes collected from D. delphis belong to Brachycladium atlanticum, while those removed from S. coeruleoalba probably represent a new species. Four species of lungworms were also identified: Halocercus delphini in S. coeruleoalba, Halocercus sp. in T. truncatus, Stenurus globicephalae in G. melas, and a potentially new Pharurus sp. in P. phocoena. Conclusion: These findings show, to the best of our knowledge, for the first time, the presence of T. gondii DNA in D. delphis. The cerebellum of the animal was Toxoplasma-infected, which might be relevant to inadvertent stranding. In this study, new genetic markers were sequenced for several helminth parasites of marine mammals, possibly including undescribed species. [ABSTRACT FROM AUTHOR]

This study investigated the presence of ectoparasites in stranded cetaceans along the coast of Sergipe, Brazil. The parasitological material, dates and informations about the hosts was obtained from a biological collection. Were analysed four Megaptera novaeangliae, one of Sotalia guianensis, and one of Peponocephala electra. A total of 264 ectoparasites were collected from these carcasses – 263 amphipods of the species Cyamus boopis and Syncyamus ilheusensis, and a single cymothoid isopod, identified as Livoneca redmanii. C. boopis showed a average intensity of 77.0 parasites per host, and a prevalence of 100% in the analysed humpback whale carcasses, representing the first record of this louse species on humpback whales in the region. S. ilheusensis appears to have a rare occurrence and specificity to the host P. electra, being its third report in the scientific literature. Additionally, the discovery of the isopod L. redmanii on Sotalia guianensis is unprecedented, being the first report of an isopod parasitizing this cetacean and expanding our knowledge about the host flexibility of this ectoparasite. The attachment of the isopod to the dolphin's skin was likely favored by the absence of mucus, as found in fish. These findings provide new insights into the ecology of these ectoparasites. [ABSTRACT FROM AUTHOR]

Goose-beaked whales (Ziphius cavirostris) are deep-diving cetaceans known for their elusive nature and specialized foraging behavior. In 2019 and 2020, six telemetry tags were deployed on these whales in Southern California, resulting in 395 h of acoustic and diving data. Foraging dives were manually identified by the presence of echolocation pulses and buzzes, and generalized additive models assessed factors influencing foraging behavior. The median bathymetric depth at foraging sites was 1,419 m (IQR = 359), and the maximum dive depth was highly correlated with bathymetry depth. Individuals started echolocating on descent at a median depth of 410 m (IQR = 74); pulses were not observed shallower than 292 m. Echolocation ceased during the bottom phase for 81.6% of dives, at a median depth of 1,265 m (IQR = 472); pulses were not observed shallower than 587 m on ascent. The median depth of buzzes was 1,215 m (IQR = 479) with 63% occurring during the bottom phase. Deeper dives correlated with longer durations of diving and echolocation, greater echolocation end depths, and wider bottom phase echolocation depth inter-quartile range. The median difference between dive depth and bottom phase median echolocation depth was 98.3 m (IQR = 48.5), suggesting whales in this region forage in a narrow band close to the seafloor. In the San Nicolas Basin, individuals exhibited longer echolocation durations, produced more pulses, and started and ended echolocating at greater depths compared to adjacent regions. These records validate and expand upon previous studies, providing insights into factors influencing foraging behavior in an area with high anthropogenic disturbance. [ABSTRACT FROM AUTHOR]

Simple Summary: The present report describes the first molecular detection of a gammacoronavirus in a free-ranging striped dolphin coinfected with cetacean morbillivirus and found stranded on the Croatian coastline in 2022. The virus was detected in a heart sample and appeared different from previously identified cetacean gammacoronaviruses. This finding underscores the necessity of including this pathogen into routine diagnostics for stranded dolphins to gather important epidemiological data on coronavirus prevalence and its potential role in causing disease. This case report presents the first molecular identification of a gammacoronavirus in a free-ranging striped dolphin (Stenella coeruleoalba) that was found stranded along the Croatian coastline in 2022. The dolphin exhibited a concurrent infection with cetacean morbillivirus. The gammacoronavirus strain was amplified and sequenced from heart tissue imprinted on an FTA®card, revealing a notable genetic distance (approximately 8%) from previously characterized cetacean gammacoronaviruses. This finding highlights the importance of including gammacoronaviruses in routine diagnostics for stranded dolphins to gather epidemiological data on their prevalence and potential role in causing disease in cetaceans. This study sets the premises for a further understanding of the diversity and distribution of gammacoronaviruses in marine mammals and highlights the necessity for ongoing surveillance of emerging infectious diseases in wild populations. [ABSTRACT FROM AUTHOR]

Cetaceans play a crucial role in marine ecosystems; however, research on their gastrointestinal microbiota remains limited due to sampling constraints. In this study, we collected hindgut samples from 12 stranded cetaceans and performed 16S rRNA gene amplicon sequencing to investigate microbial composition and functional potentials. Analysis of ZOTUs profiles revealed that the phyla Firmicutes, Proteobacteria, and Bacteroidetes dominated all hindgut samples. However, unique microbial profiles were observed among different cetacean species, with significant separation of gut microbiota communities according to biological evolutionary lineages. Different genera that contain pathogens were observed distinguishing delphinids from physeteroids/ziphiids. Delphinid samples exhibited higher abundances of Vibrio, Escherichia, and Paeniclostridium, whereas physeteroid and ziphiid samples showed higher abundances of Pseudomonas, Enterococcus, and Intestinimonas. Functional analysis indicated convergence in the gut microbiota among all cetaceans, with shared bacterial infection pathways across hindgut samples. In addition, a comparison of the gastrointestinal microbial composition between a stranded short-finned pilot whale (Globicephala macrorhynchus) and a stranded roughtoothed dolphin (Steno bredanensis) using 16S rRNA gene sequencing revealed distinct microbial community structures and functional capacities. To the best of our knowledge, this study represents the first report on the gastrointestinal microbiota of the pantropical spotted dolphin (Stenella attenuata), Blainville’s beaked whale (Mesoplodon densirostris), and rough-toothed dolphin, with various comparisons conducted among different cetacean species. Our findings enhance the understanding of microbial composition and diversity in cetacean gastrointestinal microbiota, providing new insights into co-evolution and complex interactions between cetacean microbes and hosts. [ABSTRACT FROM AUTHOR]

Pacific fin whales (Balaenoptera physalus velifera), once the most abundant cetacean species in British Columbia (BC), were also one of the most heavily targeted by commercial whaling. Much of what we know about their phenology and ecology is from catch records, but their current status has not yet been summarized in Canadian waters. Here, we collated evidence from dedicated surveys, opportunistic sightings, and passive acoustic records that had not been reported before and reviewed them in the context of past data. This was to add new findings to what is known, and to establish if the population was showing signs of recovery. This is particularly relevant considering discussions of downlisting their population status in Canada from endangered to threatened. We then asked if this rebounding was consistent with what is known about pre-whaling presence and movement patterns, or if changes in whale distribution reflected altered oceanic regimes, prey availability, or increased anthropogenic pressures. The evidence suggested that fin whale populations in the northeast Pacific Ocean are repopulating areas along the BC coast recognized as part of their historic range. However, they are recovering in a different ocean than they were removed from, which makes them increasingly vulnerable to new anthropogenic threats. The sightings data suggested that, at least for the west coast of Vancouver Island, this repopulation has occurred over a relatively short period, with fin whales still absent from regular surveys as recent as the early 2000's. The recent acoustic recordings suggested their presence is not transitory, but that fin whales may be using locales along the BC coast for feeding and breeding activities. [ABSTRACT FROM AUTHOR]

In 2016, a design for detecting harbor porpoises (Phocoena phocoena) in the Belgian part of the North Sea (BPNS) was developed in the framework of the LifeWatch project using Passive Acoustic Monitoring (PAM) loggers. In 2018, the network of deployments fully matured, and eight locations across the BPNS are presently housed with a C-POD (Chelonia Ltd., UK), a PAM logger moored on the seafloor using a multi-use platform. The PAM logger continuously listens for harbor porpoise click trains, but only stores the click parameters. This paper presents the generated data series of harbor porpoise click trains at a minute-resolution and the details on the individual click trains. The field recordings, methodology and processing are described, along with its data curation, integration and quality control. The data are annually published online in a standardized format, accompanied with the metadata description, and labelled with a digital object identifier for traceability. Data are published under a CC-BY license, allowing the use of data under the condition of providing reference to the original source. [ABSTRACT FROM AUTHOR]

Background: Habitat transitions have considerable consequences in organism homeostasis, as they require the adjustment of several concurrent physiological compartments to maintain stability and adapt to a changing environment. Within the range of molecules with a crucial role in the regulation of different physiological processes, neuropeptides are key agents. Here, we examined the coding status of several neuropeptides and their receptors with pleiotropic activity in Cetacea. Results: Analysis of 202 mammalian genomes, including 41 species of Cetacea, exposed an intricate mutational landscape compatible with gene sequence modification and loss. Specifically for Cetacea, in the 12 genes analysed we have determined patterns of loss ranging from species-specific disruptive mutations (e.g. neuropeptide FF-amide peptide precursor; NPFF) to complete erosion of the gene across the cetacean stem lineage (e.g. somatostatin receptor 4; SSTR4). Conclusions: Impairment of some of these neuromodulators may have contributed to the unique energetic metabolism, circadian rhythmicity and diving response displayed by this group of iconic mammals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cetacean strandings are valuable sources of data about their life history, health status, population trends, and impact of threats. We examined the strandings along the Bulgarian coast of the Black Sea for a period of 13 years from 2010 to 2022. A total of 1528 cetacean strandings of all three species inhabiting the basin were recorded: 1031 harbour porpoises Phocoena phocoena, 199 bottlenose dolphins Tursiops truncatus, 97 common dolphins Delphinus delphis, 19 delphinids and 182 unidentified. The highest numbers were observed in 2016 and 2022. Monthly peaks for harbour porpoise and bottlenose dolphin were in July and August and for common dolphin in May. An unusually high mortality of porpoise neonates was recorded in 2015 and 2016. The overall sex ratio showed a slightly higher share of males at 120:100. This bias was the most pronounced for males of common dolphins. Spatial distribution varied interspecifically but was predominantly along the southern coast. Bycatch signs were detected in 80 animals including during the turbot fishing ban period, suggesting the existence of illegal fishing operations. All of this highlights the need for better reinforcement and control to ensure both the conservation of endangered cetaceans and the sustainability of fisheries. Improvement in data collection is needed to improve the quality of information. [ABSTRACT FROM AUTHOR]

The Natural History Museum of the University of Pisa hosts the most important osteological collection of extant cetaceans in Italy as well as one of the most relevant all over Europe. Furthermore, it also preserves a significant palaeontological collection that includes several holotypes and otherwise unique specimens of Archaeoceti (archaic cetaceans), Mysticeti (baleen whales) and Odontoceti (toothed whales). Here, we provide a historical overview of these collections and the corresponding displays, with special attention paid to the origin, development and design of the 'Archaeocete Hall' and 'Cetacean Gallery'. These comprise what may be the largest exhibition worldwide among those dedicated exclusively to cetaceans—one that includes 28 complete skeletons and one skull belonging to 27 extant species as well as fossils of nine extinct species. Our review also reveals that the museum exhibitions feature the oldest known specimen of Mesoplodon bowdoini and the type specimen of Ziphius savi, the latter being a validly described species that is currently regarded as a junior synonym of Ziphius cavirostris. Also significant is the display of several holotype specimens of fossil species such as the protocetid archaeocete Aegyptocetus tarfa, the balaenid baleen whales Balaena montalionis and Balaenula astensis, and the monodontid Casatia thermophila. The Archaeocete Hall and Cetacean Gallery are highly appreciated by visitors as well as perused by the museum's educational team. The online archiving of 3D models of many of the MSNUP specimens on the open-access digital repository Sketchfab and their subsequent dissemination through the Wikimedia platforms has led to the creation of a major osteological resource—one that is broadly accessible to internet users worldwide. [ABSTRACT FROM AUTHOR]

Coronodon includes species of basal toothed mysticetes that were initially interpreted as engaging in raptorial feeding and dental filtration. Here, the feeding of this extinct genus is revisited based on recently described specimens and species. Associations between tooth position and types of dental wear were tested, and evidence for feeding behaviors was tabulated using scores from 14 craniodental characters, each mapped onto five alternate phylogenetic hypotheses. Individual character states were interpreted as being supportive, neutral, or contradictory evidence to raptorial feeding, suction feeding, baleen filtration, or dental filtration. Wear in Coronodon was found to be significantly more concentrated on mesial teeth, mesial cusps, higher cusps, and upper teeth. Upper teeth also had mesial cusps more worn than distal cusps, inconsistent with predictions of the dental filtration hypothesis. Wear in notches was correlated with wear on neighboring cusps, and side wear was concentrated on occlusal sides, suggesting both were caused by raptorial feeding. These observations raise the possibility that raptorial feeding was the primary, and maybe even the only, mode of feeding for Coronodon. The feeding scores of reconstructed ancestors leading to crown mysticetes typically display a stepwise decrease in raptorial feeding, a stepwise increase in baleen filtration, and, occasionally, an intermediate but weakly supported stage of dental filtration. For most toothed mysticetes, there is little evidence for or against suction feeding. The method we have developed for studying the origin of baleen can be expanded and allows for multiple hypotheses to be tested without undue emphasis on any particular taxon or set of characters. [ABSTRACT FROM AUTHOR]

Studying the abundance, distribution, and habitat use of dolphins can provide essential information for preserving marine biodiversity, managing coastal ecosystems, and enhancing our understanding of aquatic life. Herein, we investigated the abundance, distribution, and habitat use of two dolphin populations--Guiana dolphins (Sotalia guianensis) and common bottlenose dolphins (Tursiops truncatus)--in the Gulf of Urabá, Colombian Caribbean. Between 2017 and 2020, 34 non-systematic surveys were conducted across the studied region, amounting to an effort of 176.69 hours and covering 3,658.33 km, with a dolphin encounter probability rate of 8.65%. The Guiana dolphin population was estimated at 63 (95% CI = 53 to 76) individuals, whereas the common bottlenose dolphin population was estimated at 50 (95% CI = 43 to 58) individuals. The dolphins were mainly found in the central region of the Gulf, particularly around the Atrato River mouth and the east side of the estuary. Both species showed a preference for coastal areas with maximum depths of 20 m, and the Guiana dolphins showed a permanent presence in the Gulf of Urabá region. These findings indicate that the Gulf of Urabá acts as a crucial habitat and feeding ground for both Guiana and common bottlenose dolphins. Therefore, systematic monitoring programmes aiming to protect dolphin populations and their ecosystems from threats posed by coastal development, which currently endanger both species in the area, should be implemented. [ABSTRACT FROM AUTHOR]

Simple Summary: Red Data Books, by encompassing comprehensive lists of species and their statuses, are crucial indicators of the health of the world's biodiversity and powerful tools to guide conservation actions. Moreover, the adopted IUCN system for extinction risk assessment, structured around specific categories and criteria, provides an objective framework that enhances our understanding of the conservation trends of individual species over time. This study outlines the procedures used for collecting, processing, and categorizing data concerning the most recent additions to the list of mammals on mainland Portugal, as documented in the recently revised Red Book. This selection is based on three requirements: (i) species newly recorded, (ii) species newly designated taxonomically, and (iii) newly occasional species. A total of 10 species meet the requirements (i) and (ii), organized into four taxonomic groups: Eulipotyphla (1), Chiroptera (4), Rodentia (2), and Cetacea (3). All these species have been assessed for the first time, with most falling into a threatened category. Additionally, six more Cetacea species were listed as vagrant at a regional level (requirement iii) and were not considered for category assignment in the Red Data Book. This study outlines the procedures used for collecting, processing, and categorizing data on 16 new mammal species for mainland Portugal, belonging to four taxonomic groups: Eulipotyphla (1), Chiroptera (4), Rodentia (2), and Cetacea (9). Data collection and processing encompassed field and lab work and bibliographic compilation. Data categorization involves, whenever possible, the assessment of the approximate number of mature individuals in populations, the extent of occurrence, and the area of occupancy. The approach employed led to the classification of eight out of the 16 species into an IUCN category: two non-volant small mammals and one bat species were designated as Vulnerable, requiring ongoing monitoring; one rodent and three cetaceans were assigned to Data Deficient due to insufficient available information; and a single bat species was classified as Least Concern due to the high abundance of local populations. For small mammals and bats, alterations to natural systems and climate change emerged as the most relevant threatening factors, while for cetaceans, human activities such as fishing, commercial shipping, and tourism were identified as the primary survival risks. It is recommended to maintain action programs that assist in defining strategic orientations for the implementation of conservation measures on a case-by-case basis. [ABSTRACT FROM AUTHOR]

The monitoring of stranded marine mammals represents a strategic method to assess their health, conservation status, and ecological role in the marine ecosystem. Networks worldwide track stranding events for the passive monitoring of mortality patterns, emerging and reemerging pathogens, climate change, and environmental degradation from a One Health perspective. This study summarizes pathogen prevalence data from the Italian Stranding Network (ISN) derived from post-mortem investigations on cetaceans found dead stranded along the Italian coastline between 2015 and 2020. The decomposition of the carcasses and logistics limited the post-mortem examination to 585 individuals, out of 1236 single-stranding reports. The most relevant pathogens identified were Cetacean Morbillivirus, Herpesvirus, Brucella spp., and Toxoplasma gondii, whose roles as environmental stressors are well known, despite their real impact still needing to be investigated in depth. Statistical analysis showed that age and sex seem to be positively related to the presence of pathogens. This study represents the first step in harmonizing post-mortem investigations, which is crucial for evidence-based conservation efforts. Implementing diagnostic and forensic frameworks could offer an indirect insight into the systematic monitoring of diseases to improve the identification of regional and temporal hotspots in which to target specific mitigation, management, and conservation strategies. [ABSTRACT FROM AUTHOR]

Assessing trends in population abundance and demographics is crucial for managing long‐lived and slow‐reproducing species. Obtaining demographic data, and age‐structure information, is challenging, notably for cetaceans. To address this, we combined Unoccupied Aerial System (UAS; drone) photogrammetry data with long‐term (>20 years) photo identification data to assess the age‐structure of the critically endangered sub‐population of common bottlenose dolphins (Tursiops truncatus) of the Gulf of Ambracia, Greece. We compared our findings with two extensively studied non‐endangered bottlenose dolphin populations (T. aduncus in Shark Bay, Australia, and T. truncatus in Sarasota Bay, USA). Using a log‐linear model, we estimated the total body lengths (TL) of 160 known‐aged dolphins between 2021 and 2023 from blowhole‐to‐dorsal‐fin distance (BHDF) measurements collected during surfacing. Subsequently, we tested four growth models to establish an age‐length growth curve. We assessed the sub‐population's age‐structure using three methods: (1) UAS‐derived TL estimates, (2) age‐length growth curve and (3) long‐term monitoring data (i.e. actual age‐structure). UAS‐measured TL (247.6 ± 32.2 cm) and UAS‐estimated TL (246.0 ± 34.7 cm) of the Greek sub‐population showed no differences. The Richards Growth model suggested an asymptotic length of 258.5 cm. In Greece, resulting age‐structure estimates across the three methods revealed no significant differences (P > 0.1). The Gulf of Ambracia and Shark Bay populations shared similar age‐structures, while Sarasota had higher proportions of 2–10 year‐olds and lower proportions of 10+ year‐olds. All populations had a comparable proportion of 0–2 year‐olds (~14%), indicating a similar reproductive rate. Our findings suggest stability in the Greek sub‐population; however, additional monitoring of reproductive parameters is essential before concluding its status. We demonstrated the effectiveness of UAS‐photogrammetry in rapidly quantifying population age‐structure, including scenarios with limited or no demographic data. This technique shows promise for enhancing precision, timeliness, cost‐effectiveness and efficiency in population monitoring and informing timely conservation management decisions. [ABSTRACT FROM AUTHOR]

Coastal bottlenose dolphin populations are highly vulnerable due to their small population sizes and proximity to human activities. Long‐term studies in the UK have monitored populations protected within Special Areas of Conservation (SACs) since the 1990s, but a small community of bottlenose dolphins inhabiting the coastal waters of southern England has received much less attention. The English Channel is one of the most heavily impacted marine ecosystems worldwide and increasing anthropogenic pressures pose a severe threat to the long‐term viability of this population. Conservation measures to protect these animals have been hindered by a lack of knowledge of population size, distribution and ranging behaviour. This study aimed to fill these knowledge gaps. A citizen science sighting network yielded 7458 sighting reports of bottlenose dolphins between 2000 and 2020. Resightings of identified individuals were used to estimate abundance, distribution, and ranging behaviour. Social structure analysis revealed a discrete interconnected group of animals in shallow coastal waters, which did not appear to mix with conspecifics identified further offshore. A Bayesian multi‐site mark–recapture analysis estimated that this population comprises around 48 animals (CV = 0.18, 95% HPDI = 38–66). These dolphins ranged between North Cornwall and Sussex, with an average individual range of 530 km (68–760 km). Areas of high‐modelled habitat suitability were found to overlap with high levels of anthropogenic pressure, with pollution and boat traffic identified as the most pervasive threats. Although adult survival rates indicated that the population was relatively stable from 2008 to 2019 (0.945 (0.017 ± SE)), the small population size implies a significant risk to their long‐term viability and resilience to environmental change. By highlighting the most deleterious anthropogenic activities and regions of conservation significance, our results will be useful for developing management policies for threat mitigation and population conservation, to protect this vulnerable group of dolphins. [ABSTRACT FROM AUTHOR]

Recently, an acoustic individual identification (AIID) approach based on recognition of dolphins by individually distinctive calls such as "signature whistles" has been applied to bottlenose dolphins Tursiops truncatus. Some other Odontoceti species can also have individually specific calls: e.g., in beluga whales Delphinapterus leucas, these are so-called "contact calls". In this pilot study, we have tested the possibility of using the presumed contact calls of belugas to obtain the data on occurrence, number, and individual composition of their local aggregations in the natural environment. We have concluded that the diversity of contact calls can serve as an acceptable indicator of the number of individuals in the research area; in addition, these calls are potentially applicable for individual acoustic identification in belugas. [ABSTRACT FROM AUTHOR]

The north-western coast of Africa is one of the most productive marine systems in the world, where a high diversity of cetacean species has been recorded. However, management of human activities that impact cetacean populations in the area is inadequate, in part due to poor knowledge on cetacean occurrence and the lack of systematic surveys. We reviewed existing knowledge on cetacean distribution between Morocco and Liberia and analyzed the spatial and temporal distribution of records, as well as species occurrence, further discussing the reported distribution ranges. The systematic literature review included 39 sources reporting on 36 species in the area, with a total of 2241 sightings and 2178 non-sighting records. Delphinus delphis (common dolphin) and Tursiops truncatus (bottlenose dolphin) are the two species with the highest number of sources reporting on them. This review reveals a spatially and temporally heterogeneous coverage of the area in the literature and published data on cetacean occurrence. In summary, although most of the compiled sources are recently published (2011-2020), the majority of records are from prior to 2000. In several range states, especially south of Senegal, little information is available. Therefore, the available information is unlikely to represent the current status of cetacean communities in the region. It is essential to fill knowledge gaps by increasing the collection of cetacean distribution data in the area, in order to support effective conservation measures and ensure sustainable utilization of the living marine resources in this rapidly developing region. [ABSTRACT FROM AUTHOR]

Industrial effluents contain the hazardous metal hexavalent chromium [Cr(VI)], which is potentially lethal to all organisms in the environment. In this work, we developed a transition metal chalcogenide (TMC)-based reduced graphene oxide (rGO) nanocomposite (CeTe/rGO) via the hydrothermal method for the photoreduction of chromium(VI) metal into less hazardous Cr(III). Various analytical tools including x-ray diffraction (XRD), UV–visible spectroscopy (UV–Vis), Brunauer-–Emmett–Teller (BET) and scanning electron microscopy (SEM) analysis were employed for determining characteristics of the CeTe/rGO photocatalyst. The photocatalytic efficiency of transition metal chalcogenide-based rGO nanocomposite was measured under UV–Vis light with a UV–Vis spectrophotometer. The photocatalytic efficiency of CeTe (76.54%) and rGO (81.94%) is smaller than that of the CeTe/rGO (96.50%) due to the larger surface area of the rGO. Scavengers analysis revealed that superoxide anion, hydroxyl radical and holes play a great role in the photocatalysis process. Our results suggest that the CeTe/rGO nanocomposites can potentially be used to reduce the toxic material present in the environment. [ABSTRACT FROM AUTHOR]

The Natural History Museum of the University of Pisa hosts the most important osteological collection of extant cetaceans in Italy as well as one of the most relevant all over Europe. Furthermore, it also preserves a significant palaeontological collection that includes several holotypes and otherwise unique specimens of Archaeoceti (archaic cetaceans), Mysticeti (baleen whales) and Odontoceti (toothed whales). Here, we provide a historical overview of these collections and the corresponding displays, with special attention paid to the origin, development and design of the ‘Archaeocete Hall’ and ‘Cetacean Gallery’. These comprise what may be the largest exhibition worldwide among those dedicated exclusively to cetaceans—one that includes 28 complete skeletons and one skull belonging to 27 extant species as well as fossils of nine extinct species. Our review also reveals that the museum exhibitions feature the oldest known specimen of Mesoplodon bowdoini and the type specimen of Ziphius savi, the latter being a validly described species that is currently regarded as a junior synonym of Ziphius cavirostris. Also significant is the display of several holotype specimens of fossil species such as the protocetid archaeocete Aegyptocetus tarfa, the balaenid baleen whales Balaena montalionis and Balaenula astensis, and the monodontid Casatia thermophila. The Archaeocete Hall and Cetacean Gallery are highly appreciated by visitors as well as perused by the museum’s educational team. The online archiving of 3D models of many of the MSNUP specimens on the open-access digital repository Sketchfab and their subsequent dissemination through the Wikimedia platforms has led to the creation of a major osteological resource—one that is broadly accessible to internet users worldwide.

The southern right whale dolphin, Lissodelphis peronii (Lacépède, 1804), is a species of cetacean that is distributed in cold and deep waters throughout the Southern Hemisphere, with records in coastal waters of the western Atlantic Ocean being extremely rare. On January 7, 2019, a specimen still alive, was recorded entangled in a fishing gillnet on the beach at Cardoso Beach (28°44′S, 48°58′W), in the state of Santa Catarina, on the southern coast of Brazil. The recording was made by a lifeguard using a GoPro camera and was made available through citizen science. The animal was untangled and released while still alive and was not found stranded again after the date of the event. Based on existing literature, this is the second record of the species in Brazilian waters. Analyzing meteorological and oceanographic features from the days preceding the record, it was not possible to make any association between the entanglement and the variables analyzed, and no explanatory driver could therefore be established for this unusual event. [ABSTRACT FROM AUTHOR]

Abstract Background To reduce heat loss underwater, marine mammals cover their bodies with insulation. Cetaceans in particular rely solely on blubber for insulation which has low conductivity. Blubber establishes a great thermal gradient between the warmer body core and cooler body surface, reducing heat transfer to the environment. A temperature gradient within the blubber determines the conductive heat transfer from the body trunk, where conduction and convection are the primary heat transfer mechanisms in cetaceans. Therefore, measuring the temperature at the innermost part of the blubber, i.e., the temperature at the muscle–blubber interface (Tmbi), can enhance our understanding of thermoregulatory mechanisms in cetaceans. In thermoregulation, activity-induced heat produced by increased muscle metabolism is another factor that plays an important role, however, the effects of activity on Tmbi have not been investigated in cetaceans. To assess this relationship in free-swimming cetaceans, we measured Tmbi and activity levels in a captive Risso’s dolphin (Grampus griseus) using an implantable biologging device. Results Tmbi and activity data were analyzed for 11 days. The average Tmbi was 35.1 ± 0.6 ºC and the temperature gradient between Tmbi and the water temperature was 13.0 ± 0.7 ºC. Tmbi was higher during the daytime and lower in the early morning. The variation in Tmbi was best explained by both the activity levels and time of day. Tmbi did not simply increase with activity levels; it appeared to remain relatively constant at most activity levels. However, Tmbi appeared to decrease when the animal was inactive and increase when it was intensely active. Conclusion Our results provide important insights into how a dolphin regulates its body temperature underwater. Thermal insulation by blubber and heat production by activity were suggested to play important roles in thermoregulation. Whole-body heat dissipation might be used to regulate temperature increases when heat production is excessive due to intense activity. During inactive periods, decreasing temperature gradient may help reduce heat loss from the body.

Accurate prediction of bus arrival time is essential to achieve efficient bus dispatch and improve bus trip sharing rate. This article proposes using the improved whale optimization algorithm-long short-term memory (IWOA-LSTM) model to predict bus arrival times and improving the whale algorithm by optimizing the hyperparameters of the LSTM model, so that the advantages and disadvantages of the whale algorithm and the LSTM model can complement each other, thus enhancing the robustness of the model. Initially, the bus arrival process and its associated influencing factors are analyzed, with certain factors being quantified to serve as input features for the prediction model. After processing the GPS data of the No. 220 bus in Nanchang, Jiangxi, China, the proposed prediction model is analyzed and validated using an example and compared with other prediction models. The results show that the IWOA-LSTM prediction model has the best-fitting effect between the predicted values and actual values in all time periods. Its MAPE, RMSE, and MAE have been reduced by at least 9.47%, 12.77%, and 8.93%, respectively, and the overall R[sup.2] has been improved by at least 10.65%. These results indicate that the model has the best predictive performance., Author(s): Bing Zhang (corresponding author) [1]; Lingfeng Tang [2]; Dandan Zhou [3]; Kexin Liu [4]; Yunqiang Xue [4] 1. Introduction The continuous increase in the number of motorized vehicles has [...]

The capture and killing of free-living small cetaceans in the Faroe Islands is described. After being driven on-shore by motor vessels, the animals are killed without pre-stunning using officially-prescribed methods that involve severing the spinal cord and the associated blood vessels using a long-handled lance. The claim that this induces near instantaneous unconsciousness and death lacks supporting evidence: it is believed that the animals are simply paralyzed, not immediately rendered unconscious. The cervical and spinal arterial circulation of cetaceans differs from that of terrestrial mammals and it is likely the spinal lance does not completely destroy the supply of oxygenated blood to the brain. In conclusion, the entire process from driving the animals onto the shore, to restraint and to killing stranded cetaceans is very likely to be detrimental to their welfare. Detailed studies would be necessary to determine the veracity of the claimed efficacy of the process. A bespoke humane killer may improve welfare at the time of killing but its development is considered challenging. [ABSTRACT FROM AUTHOR]

Cetaceans represent a natural experiment within the tree of life in which a lineage changed from terrestrial to aquatic habitats. This shift involved phenotypic modifications, representing an opportunity to explore the genetic bases of phenotypic diversity. Among the different molecular systems that maintain cellular homeostasis, ion channels are crucial for the proper physiological functioning of all living species. This study aims to explore the evolution of ion channels during the evolutionary history of cetaceans. To do so, we created a bioinformatic pipeline to annotate the repertoire of ion channels in the genome of the species included in our sampling. Our main results show that cetaceans have, on average, fewer protein-coding genes and a higher percentage of annotated ion channels than non-cetacean mammals. Signals of positive selection were detected in ion channels related to the heart, locomotion, visual and neurological phenotypes. Interestingly, we predict that the NaV1.5 ion channel of most toothed whales (odontocetes) is sensitive to tetrodotoxin, similar to NaV1.7, given the presence of tyrosine instead of cysteine, in a specific position of the ion channel. Finally, the gene turnover rate of the cetacean crown group is more than three times faster than that of non-cetacean mammals. [ABSTRACT FROM AUTHOR]

Under global warming, impacts on animals' spatial distribution in response to ocean warming have been anticipated for marine endotherms like cetaceans. Therefore, determining the distribution patterns of small cetaceans is key to understanding how their distributional patterns are susceptible to changing oceanic environments. To investigate the effect of environmental variations on distributional patterns of small cetaceans on a fine scale, we attached eight satellite tags to Dall's porpoises bycaught in Eastern Hokkaido. After release, the tagged porpoises moved into the western North Pacific and its marginal sea, the Sea of Okhotsk. Our tagging results showed that the habitat ranges of Dall's porpoises were restricted by water temperature. To avoid warm water, tagged porpoises changed their directions when they faced surface thermocline of 17°C. Dall's porpoise tracked for the longest periods (116 days) showed southwestward movement after entering the Sea of Japan through the Soya Strait, while the other seven tagged porpoises stayed in the Sea of Okhotsk and off the Pacific coast around Hokkaido and Chishima islands for the entire tracking periods. Vertical movements were also recorded by these tags. Long-term tracking of Dall's porpoises' movement provides important insights into seasonal migration patterns, particularly for fall southward migration, which has not been well investigated compared with spring northward migration. Information on seasonal migration, distribution and percentage of time spent at the surface will improve our approach to monitoring Dall's porpoise populations and discover important knowledge for improving the conservation and management of the population. [ABSTRACT FROM AUTHOR]

Strandings and opportunistic sightings represent an invaluable source of information on cetacean’s biodiversity in the Mexican Caribbean. Here, we document the stranding and rescue of two pantropical spotted dolphins Stenella attenuata (mother and male calf) near Tulum (Quintana Roo, Mexico), which died without a clear diagnosis of cause of death. This case confirms the occurrence of S. attenuata, increasing the number of local aquatic mammals to 20. As most of the other small cetaceans in this region, the conservation status of the species remains undefined, and more research is needed to better understand ecological and biological aspects of its population. [ABSTRACT FROM AUTHOR]

Sperm whales exhibit sexual dimorphism and sex-specific latitudinal segregation. Females and their young form social groups and are usually found in temperate and tropical latitudes, while males forage at higher latitudes. Historical whaling data and rare sightings of social groups in high latitude regions of the North Pacific, such as the Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BSAI), suggest a more complex distribution than previously understood. Sperm whales are the most sighted and recorded cetacean in marine mammal surveys in these regions but capturing their demographic composition and habitat use has proven challenging. This study detects sperm whale presence using passive acoustic data from seven sites in the GOA and BSAI from 2010 to 2019. Differences in click characteristics between males and females (i.e., inter-click and inter-pulse interval) was used as a proxy for animal size/sex to derive time series of animal detections. Generalized additive models with generalized estimation equations demonstrate how spatiotemporal patterns differ between the sexes. Social groups were present at all recording sites with the largest relative proportion at two seamount sites in the GOA and an island site in the BSAI. We found that the seasonal patterns of presence varied for the sexes and between the sites. Male presence was highest in the summer and lowest in the winter, conversely, social group peak presence was in the winter for the BSAI and in the spring for the GOA region, with the lowest presence in the summer months. This study demonstrates that social groups are not restricted to lower latitudes and capture their present-day habitat use in the North Pacific. It highlights that sperm whale distribution is more complex than accounted for in management protocol and underscores the need for improved understanding of sperm whale demographic composition to better understand the impacts of increasing anthropogenic threats, particularly climate change. [ABSTRACT FROM AUTHOR]

Remoras are a highly specialised group of fishes known to associate with a range of marine megafauna, including elasmobranchs, cetaceans and marine reptiles. Remoras appear to benefit from these interspecific interactions through consumption of host dermal parasites or reduced cost of transport. Shark‐remora associations are widely documented, yet our understanding of the costs and benefits involved in these interactions is poor. Studies frequently make claims about mutualistic, commensalistic or parasitic relationships without providing the necessary quantitative information necessary to make these claims. Here I explain why this approach is problematic, and proceed to examine shark‐remora interactions in a rigorous eco‐evolutionary framework. These interactions cannot be properly classified without considering net evolutionary fitness and context dependence. In reality, shark‐remora interactions are best defined by a multidimensional spectrum of fitness consequences, with net fitness outcomes shifting between mutualism and parasitism (and vice versa) through space and time. [ABSTRACT FROM AUTHOR]

Species distribution models (SDMs) can be used to predict distributions in novel times or space (termed transferability) and fill knowledge gaps for areas that are data poor. In conservation, this can be used to determine the extent of spatial protection required. To understand how well a model transfers spatially, it needs to be independently tested, using data from novel habitats. Here, we test the transferability of SDMs for Hector's dolphin (Cephalorhynchus hectori), a culturally important (taonga) and endangered, coastal delphinid, endemic to Aotearoa New Zealand. We collected summer distribution data from three populations from 2021 to 2023. Using Generalised Additive Models, we built presence/absence SDMs for each population and validated the predictive ability of the top models (with TSS and AUC). Then, we tested the transferability of each top model by predicting the distribution of the remaining two populations. SDMs for two populations showed useful performance within their respective areas (Banks Peninsula and Otago), but when used to predict the two areas outside the models' source data, performance declined markedly. SDMs from the third area (Timaru) performed poorly, both for prediction within the source area and when transferred spatially. When data for model building were combined from two areas, results were mixed. Model interpolation was better when presence/absence data from Otago, an area of low density, were combined with data from areas of higher density, but was otherwise poor. The overall poor transferability of SDMs suggests that habitat preferences of Hector's dolphins vary between areas. For these dolphins, population‐specific distribution data should be used for conservation planning. More generally, we demonstrate that a one model fits all approach is not always suitable. When SDMs are used to predict distribution in data‐poor areas an assessment of performance in the new habitat is required, and results should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Research on predator–prey interactions between sharks and cetaceans remain limited. Here, we report on a video of a shortfin mako shark circling a finless porpoise with a damaged caudal fin in the Seto Inland Sea, Japan. The finless porpoise was neither emaciated nor inactive, but unable to swim effectively due to the complete lack of a caudal fin. Some circumstantial evidence, including a bite mark on the porpoise's head, strongly suggests that the mako shark attacked it. Furthermore, the possible time difference between the two injuries the porpoise sustained may reflect the shark's hunting tactics. While mako sharks primarily feed on small fish and cephalopods, this observation suggests they also may prey on live cetaceans more often than previously thought. [ABSTRACT FROM AUTHOR]

This follow-up study to the first assessment of Philippine marine mammal strandings (1998 to 2009) assesses the spatiotemporal variation of strandings and the top five most frequently stranded species from a 2005-2022 dataset. It identifies stranding hotspot areas, estimates species stranding rates/status, and examines species composition and other stranding information. The 18-year database contained 1,368 stranding events with an annual average of 76 events. The total annual stranding frequency increased over the initial study period but fluctuated in the last seven years. Of the 30 species of marine mammals known in the Philippines, 27 species (26 cetaceans and one sirenian) were recorded in stranding records, and the top five most frequently stranded were (1) spinner dolphins (Stenella longirostris), (2) dugongs (Dugong dugon), (3) Risso’s dolphins (Grampus griseus), (4) Fraser’s dolphins (Lagenodelphis hosei), and (5) melonheaded whales (Peponocephala electra). Strandings consisted mostly of single animals (95%), and 55% of animals stranded alive. For each of the top five species, the frequency of stranding events increased annually. There was a peak in stranding frequency during the pre-southwest inter-monsoon season (March-April-May) for spinner and Risso’s dolphins as well as melon-headed whales, with no seasonal trend for the Fraser’s dolphins and dugongs. We identified stranding hotspots within 15 × 15 km grids along the coastline of the major island groups: Luzon, Visayas, and Mindanao. Thirty-five percent (497 of 1,422 grids) of the Philippine coastline had stranding records, with the majority in Luzon (n = 238), followed by Mindanao (n = 130) and Visayas (n = 128). Thirty-five stranding hotspots were identified: 24 in Luzon, 10 in Mindanao, and one in Visayas. Species stranding status categories were generated from log transformed stranding rates per species into standardized classification by quartiles. The stranding status of the top five most frequently stranded species was “very frequent” for spinner dolphins, and “frequent” for Fraser’s and Risso’s dolphins, dugongs, and melon-headed whales. The spatiotemporal variation of stranded marine mammals reflects the dynamic nature of the Philippine archipelago driven by monsoons and inter-monsoons and is exacerbated by fishing pressure and illegal activities. This study showed the importance of robust long-term marine mammal stranding databases for monitoring strandings and generating relevant information essential for their conservation. [ABSTRACT FROM AUTHOR]

There are a few mammalian lineages secondarily adapted to life in water throughout their evolutionary history. Of them, only sirenians and cetaceans evolved as fully aquatic organisms. This transition was accompanied by changes in swimming mode, from foot paddling to tail-powered propulsion, with the forelimbs acting as efficient hydrofoils and the gradual loss of external hindlimbs. Here, we describe an isolated limb from the Middle Eocene of Ukraine, 43–42 Mya, identified as a hindlimb of a fully aquatic cetacean and being the earliest cetacean reported from Europe. It is represented by flattened, jointly articulated bones, identified as the tibia and fibula with a partly reduced knee joint and loose connection to the pes, and by flattened phalanges. This anatomy reveals a hitherto only presumed cetacean morphotype, showing that some of the early fully aquatic cetaceans were four-legged animals with functional hindlimbs that could be involved in advanced styles of swimming. They used either body undulation or lift-based propulsion powered by the tail or feet and could also use a transitional swimming style combining these modes. [ABSTRACT FROM AUTHOR]

Prospecting fieldwork in a new fossiliferous locality of the marine Early Miocene Gaiman Formation (Patagonia, Argentina) results in the discovery of abundant fossil cetaceans (n = 29). We analyse stratigraphic, sedimentologic, palaeontologic, and taphonomic data with the aim of understanding the factors that control the preservation and distribution of these specimens. The cetacean sample is dominated by small odontocetes exhibiting five different preservation categories. Based on sedimentological features, three distinct facies were recognised in the stratigraphic section. Stratigraphically condensed deposits of facies C, related to a ravinement surface and subsequent transgressive deposits, enclose 52% of the specimens, grading from isolated postcranial elements to articulated and associated postcranial and cranial elements. In contrast, facies A and B exhibit predominantly isolated postcranial elements. Facies C shows higher degrees of corrosion, encrustation and fragmentation than those specimens from facies A and B, reflecting differences in preservation quality among the facies. The higher abundance and evidence of long exposure times recorded for facies C seems to be resulted mostly from physico-chemical factors after stratigraphic condensation. Finally, intrinsic biological features and ecological preferences of the specimens could explain the dominance of small-sized odontocetes in a restricted inner shelf to lower shoreface environmental setting. [ABSTRACT FROM AUTHOR]

The article discusses the legal and ethical considerations regarding the capture and care of cetaceans like whales, dolphins and porpoises. Other topics include the laws protecting marine mammals on captivity like the Marine Mammal Protection Act of 1972 (MMPA), the challenges over the release of captive cetaceans, and the complexities of creating seaside sanctuaries as a form of zoological housing and care.