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Killer whales occur in the Gulf of Mexico (GoMex) and the North Atlantic, including off the southeastern United States (SEUS). Data from cetacean surveys during 1990 – 2021 and other sources were combined to assess killer whale biology, including spatial and temporal distribution, social structure, genetics, morphology, acoustics, and predatory behavior. GoMex records occurred predominantly in oceanic waters (>200 m) during spring and summer. SEUS records occurred primarily in winter and spring off the North Carolina region along the shelf-edge and deeper waters, and off the east coast of Florida. Photo-identification analysis of GoMex killer whales resulted in 49 individuals sighted up to seven times with sighting histories up to 26 years, and social analysis provided evidence of long-term relationships up to 16 years. The GoMex genetic samples revealed two mtDNA haplotypes, one of which does not match any outside the GoMex. Most GoMex whales had wide non-faint saddle patches and many had cookiecutter shark scars while no scars were noted on SEUS whales. Three groups recorded in the GoMex made few calls, but a group harassing sperm whales produced many. Cetaceans and tuna are known prey in the GoMex and SEUS, respectively. Directed studies of killer whales in the GoMex areas would be difficult to implement as this species is very rare. It is therefore important to pursue ongoing efforts to collect behavioral, acoustic and any biological samples that will contribute to improve our understanding of the biology and ecology of killer whales in tropical and subtropical regions. [ABSTRACT FROM AUTHOR]

This article discusses observations of killer whale attacks on sei and fin whales in the Magellanic Sub-Antarctic Waters of Chile. The attacks occurred between March 2020 and April 2021 and resulted in the death of the whales. The researchers were able to identify one female killer whale involved in three of the attacks, which is relatively rare. The study emphasizes the need for further research on the trophic ecology and dietary plasticity of killer whales in the area. Additionally, a collection of articles and studies on killer whale behavior, diet, and interactions with other marine species is provided. [Extracted from the article]

Humpback whales in Bermuda have been observed engaging in a unique behavior of expanding their oral pouches and rubbing them against the seafloor. This behavior is believed to be a method of skin maintenance in areas where barnacles and whale lice congregate. The whales were observed swimming together, often in pairs, and descending into sand holes to rub their expanded pouches against the bottom. This behavior is different from feeding and may serve as a way for the whales to exfoliate and clean hard-to-reach areas of their bodies. Further research is needed to fully understand this behavior. [Extracted from the article]

The Cold Pool is a subsurface layer with water temperatures below 2 °C that is formed in the eastern Bering Sea. This oceanographic feature of relatively cooler bottom temperature impacts zooplankton and forage fish dynamics, driving different energetic pathways dependent upon Bering Sea climatic regime. Odontocetes echolocate to find prey, so tracking foraging vocalizations acoustically provides information to understand the implications of climate change on Cold Pool variability influencing regional food web processes. Vocal foraging dynamics of ice-associated and seasonally migrant marine mammal species suggest that sperm whales spend more time searching for prey in warm years when the Cold Pool is reduced but are more successful at capturing prey during cold years when the Cold Pool is stronger. Beluga whale foraging vocal activity was relatively consistent across climate regimes but peaked during the warm regime. Killer whale foraging vocal activity peaked in both warm and cold regimes with indicators of different ecotypes exploiting changing prey conditions across climate regimes. Foraging activity of odontocete apex predators may serve as a sentinel indicator of future ecosystem change related to prey availability that is linked to a diminishing Cold Pool as water temperatures rise and seasonal sea ice decreases due to climate change. [ABSTRACT FROM AUTHOR]

Toothed cetaceans represent a diverse and important component in poorly studied pelagic food webs. We used the variation in δ13C and δ15N values in tooth dentin and bone collagen sampled from 185 specimens of 23 species (families Delphinidae, Physeteridae, Kogiidae, Phocoenidae, and Ziphiidae) stranded in the western South Atlantic Ocean (WSAO) to estimate the isotopic niche width and assess the interspecific isotopic niche overlap. Two gradients of increasing δ13C values among species were evidenced: ocean-coast and high-to-low latitudes. Variation in δ13C and δ15N values indicated the existence of at least four trophic and habitat-related guilds: neritic high trophic-level predators (Pseudorca crassidens, Tursiops truncatus gephyreus, T. truncatus truncatus and Phocoena spinnipinis); oceanic intermediate trophic-level predators (Orcinus orca, Steno bredanensis, Kogia breviceps, Lagenodelphis hosei, Physeter macrocephalus, Delphinus delphis and Stenella frontalis), oceanic low trophic-level predators (Grampus griseus, P. crassidens—mass stranded group, Mesoplodon grayi, M. densirostris, Ziphius cavirostris, Globicephala melas, S. coeruleoalba, and K. sima), all from the subtropics, and a temperate/polar grouping of neritic/oceanic low trophic-level predators (Berardius arnuxii, M. layardii, M. hectori and P. dioptrica). Furthermore, our results also suggest the occurrence of putative ecotypes of O. orca and P. crassidens. The isotopic niche width was highly variable among species, with high niche overlap among several oceanic taxa. The results of the present study suggest a wide variation in trophic position, habitat and, therefore, the ecological role of different odontocete species in the WSAO ecosystems. [ABSTRACT FROM AUTHOR]

Collective decision‐making is an essential part of day‐to‐day life for group‐living animals. These decisions can be unshared (e.g. leadership) or shared (e.g. consensus).Aquatic mammals face particular challenges when making collective decisions, including a three‐dimensional habitat that can make group coordination and collective navigation a challenge.We systematically reviewed literature on decision‐making in non‐human mammals by examining the types of collective decisions observed and hypotheses used to structure analyses.Most of the current literature was centred around terrestrial species, particularly within primates and artiodactyls. There are no collective decision‐making studies on aquatic mammal species outside of cetaceans. Both unshared and shared decision‐making have been reported in whales and dolphins, with leadership found in killer whales Orcinus orca and bottlenose dolphins Tursiops sp. and consensus decisions in sperm whales Physeter macrocephalus.Five recommendations for decision‐making research include: 1) clearly delineating the temporal components of decision‐making, 2) standardising research to allow for comparisons, 3) considering both shared and unshared decision‐making, 4) analysing decision‐making across behavioural contexts, and 5) avoiding anthropomorphic terminology.Future studies of collective decision‐making will help us better understand how non‐human mammals overcome environmental and contextual challenges – particularly in the case of aquatic species such as cetaceans, which face challenges related to their aquatic environment and exhibit phenomena such as mass strandings. [ABSTRACT FROM AUTHOR]

Cetaceans' stranding data are a valuable information source about population indicators, biological analyses and causes of death. This study aimed to determine the species present on the north-western coast of Morocco, their spatio-temporal distribution and the potential causes of mortality of these stranded species. Ten cetacean species occurred on Morocco's north-western coast in the period from 2016 to 2021, from Jebha to Larache. These were bottlenose dolphin, short-beaked common dolphin, striped dolphin, common minke whale, Risso's dolphin, long-finned pilot whale, pygmy sperm whale, Cuvier's beaked whales, killer whale and harbour porpoise. The most frequently stranded species were bottlenose dolphins (n = 30), striped dolphins (n = 61) and short-beaked common dolphins (n = 43). Additionally, these species were present in the study area throughout the year. There were no significant seasonal or monthly differences in the stranding events. In this study, 54.5% of all stranding cases showed interactions mainly with fisheries. Injuries and mutilations observed in the stranded cetaceans resulted from human interactions, thus increasing their probability of stranding. [ABSTRACT FROM AUTHOR]

The article in Science Robotics discusses how AI-driven aerial robots are being used to advance whale research, specifically in monitoring sperm whales. Traditional wildlife tracking methods are time-consuming and challenging, but robotic systems, such as aerial vehicles, are making monitoring faster and more reliable. The research focuses on developing a framework called AVATARS to maximize rendezvous opportunities between autonomous aerial robots and sperm whales, addressing challenges in real-time deployment and communication systems. This research is a significant step towards long-duration autonomous marine operations and can benefit both the robotics community and marine biology in improving monitoring and tracking of marine animals and ecosystems. [Extracted from the article]

Cetaceans spend most of their time below the surface of the sea, highlighting the importance of passive acoustic monitoring as a tool to facilitate understanding and mapping their year-round spatial and temporal distributions. To increase our limited knowledge of cetacean acoustic detection patterns for the east and west coasts of Gwaii Haanas, a remote protected area on Haida Gwaii, BC, Canada, acoustic datasets recorded off SG̱ang Gwaay (Sep 2009–May 2011), Gowgaia Slope (Jul 2017–Jul 2019), and Ramsay Island (Aug 2018–Aug 2019) were analyzed. Comparing overlapping periods of visual surveys and acoustic monitoring confirmed presence of 12 cetacean species/species groups within the study region. Seasonal patterns were identified for blue, fin, humpback, grey and sperm whale acoustic signals. Killer whale and delphinid acoustic signals occurred year-round on both coasts of Haida Gwaii and showed strong diel variation. Cuvier's, Baird's, beaked whale and porpoise clicks, were identified in high-frequency recordings on the west coast. Correlations between environmental factors, chlorophyll-a and sea surface temperature, and cetacean acoustic occurrence off Gwaii Haanas were also examined. This study is the first to acoustically monitor Gwaii Haanas waters for an extended continuous period and therefore serves as a baseline from which to monitor future changes. [ABSTRACT FROM AUTHOR]

The article reports that various species of cetaceans annually visit the Pacific coast of Colombia. Topics include considered while others are present throughout the year as humpback whales belongs to breeding stock G (BSG), recognized by the International Whaling Commission are commonly seen in the Gulf of Tribugá on an annual basis.

The article describes an interaction between two cetacean species such as the sperm whale and the short-finned pilot whale. Topics include examines the event occurred on June 6, 2021 during a research survey and considered the crew of Pelagic Life, AC and the Marine Mammal Laboratory at Universidad Veracruzana was surveying the Continental Slope off the Veracruz coast in the southwestern Gulf of Mexico when a mother–calf sperm whale pair was observed.

Biggs killer whale (Orcinus orca) predation on subadult humpback whales (Megaptera novaeangliae) in lower Cook Inlet and Kodiak, Alaska. Associations with multiple male groups increase the energy expenditure of humpback whale (Megaptera novaeangliae) female and calf pairs on the breeding grounds. Escort service: Sex and relatedness of humpback whales accompanying mother-calf pairs off Western Australia Humpback whale "super-groups" - A novel low-latitude feeding behaviour of Southern Hemisphere humpback whales (Megaptera novaeangliae) in the Benguela Upwelling System. [Extracted from the article]

Human-animal interaction occurs when the actions of one affect the other; these interactions can be neutral, beneficial, or detrimental to one another (Nyhus, 2016). Avistamiento de cetáceos como herramienta para el estudio de la población de orca (Orcinus orca) en el Estrecho de Gibraltar [Whale watching as a tool for the study of the killer whale (Orcinus orca) population in the Strait of Gibraltar]. Demographic consequences of fisheries interaction within a killer whale (Orcinus orca) population. [Extracted from the article]

Ford and Reeves (2008) list four additional accounts of blue whales fleeing from killer whales (two from Gulf of California, two from central California): in two cases, the killer whales broke off after an unsuccessful chase, and in the other two the outcome was unknown. Killer whales ( I Orcinus orca i ) are apex marine predators, having been documented preying upon nearly every large animal species that swims in the ocean (Ford, 2019; Jefferson et al., 1991). At 12:08, the vessel arrived at the site where killer whales were attacking a blue whale calf that was estimated to be 10-12 m long. Additionally, from aerial drone imagery, the blue whale appeared to be roughly twice the length of the 5-6 m killer whales swimming alongside it (Figure 6). [Extracted from the article]

Female humpback whale (Megaptera novaeangliae) reproductive class and male-female interactions during the breeding season [Doctoral dissertation]. However, note that the dive behavior of PE2 and SE4 is still correlated through 13:20 even though the animal was not visually sighted again, and that both PE2 and SE4 surfaced at 13:02 at the same time as the female. Humpback whale competitive group behavior on breeding grounds was first described in the early 1980s (Baker & Herman, 1984; Mobley & Herman, 1985; Tyack & Whitehead, 1982), and has been found to be consistent across breeding grounds and ocean basins. Quantifying the behavior of humpback whales (Megaptera novaeangliae) and potential responses to sonar. [Extracted from the article]

As human activities impact virtually every animal habitat on the planet, identifying species at-risk from disturbance is a priority. Cetaceans are an example taxon where responsiveness to anthropogenic noise can be severe but highly species and context specific, with source-receiver characteristics such as hearing sensitivity only partially explaining this variability. Here, we predicted that ecoevolutionary factors that increase species responsiveness to predation risk also increase responsiveness to anthropogenic noise. We found that reductions in intense-foraging time during exposure to 1- to 4-kHz naval sonar and predatory killer whale sounds were highly correlated (r = 0.92) across four cetacean species. Northern bottlenose whales ceased foraging completely during killer whale and sonar exposures, followed by humpback, long-finned pilot, and sperm whales, which reduced intense foraging by 48 to 97%. Individual responses to sonar were partly predicted by species-level responses to killer whale playbacks, implying a similar level of perceived risk. The correlation cannot be solely explained by hearing sensitivity, indicating that species- and context-specific antipredator adaptations also shape cetacean responses to human-made noise. Species that are more responsive to predator presence are predicted to be more disturbance sensitive, implying a looming double whammy for Arctic cetaceans facing increased anthropogenic and predator activity with reduced ice cover. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Humpback whales (Megaptera novaeangliae) being cosmopolitan and highly migratory animals. Topics include found in all ocean basins and annually migrating between low-latitude waters; and growing evidence of humpback whales feeding during typical migration months being reported for non-migrant individuals.

Fishers aim to optimise cost-- benefit ratios of their behaviour when exploiting resources. Avoidance of interactions with marine predators (i.e. their feeding on catches in fishing gear, known as depredation) has recently become an important component of their decisions. How fishers minimise these interactions whilst maximising fishing success is poorly understood. This issue is addressed in a sub- Antarctic, long- line fishery confronted with extensive depredation by sperm whales Physeter macrocephalus and killer whales Orcinus orca by examining a 15- year data set. Whereas a broad range of behaviours was identified from spatio- temporal and operational descriptors, none combined high fishing success with low frequency of interactions. With experience, fishers favoured exploitation of productive patches with high frequencies of interactions over avoidance behaviours. Such decisions, although potentially optimal in the short term, are likely to intensify pressures on fish stocks and impact depredating whales. Therefore, the present study provides additional evidence to inform management decisions pertaining to the coexistence between fisheries and marine predators. [ABSTRACT FROM AUTHOR]

The occurrence of typical inter-click intervals (ICIs) is considered for the analysis of marine mammals signals. A new framework for passive acoustic monitoring is introduced based on ICI information retrieved from ocean acoustic data. The proposed scheme involves extraction of plausible click trains consist of echolocation clicks from various annotated data of marine mammals; here we investigate sperm whale (Physeter macrocephalus), Pacific white-sided dolphin (Lagenorhynchus obliquidens), and killer whale (Orcinus orca). Then a preliminary investigation on the analysis of the proposed ICI-based parameters is carried out. In order to characterize the biological clicks, some distinct information of ICI are derived from the click trains, which are extracted from the phase slope functions of the signals. The experimental results obtained from real-recorded ocean data reveal that the proposed ICI-based scheme can be a useful tool for monitoring various types of marine mammal vocalizations. [ABSTRACT FROM AUTHOR]

The article discusser the case of a Humpback whale (Megaptera novaeangliae) from the West Indies. Topics include North Atlantic Humpback Whale Catalogue (NAHWC) has identified and catalogued individuals from all major areas of humpback aggregation; and whales migrating from the Dominican Republic have been found in the higher latitude feeding grounds of the Gulf of Maine, Newfoundland, and Labrador.

UNESCO World Natural Heritage sites are established to ensure the long‐term conservation of natural areas. Nemuro Strait in northern Japan is adjacent to the Shiretoko World Natural Heritage Site, and attracts various trophic levels of marine species, including marine mammals. Although the coexistence of humans and marine mammals is an important issue in this area, the temporal habitat use of cetaceans in this area is unknown. Here, we document seasonal and diel changes in cetacean vocalizations collected using passive acoustic recording devices during November 2012–March 2014. Killer whale calls occurred in spring and summer, and sperm whale clicks were detected in summer. Pacific white‐sided dolphin calls were recorded in summer and late fall. No cetaceans were recorded during the sea ice period in February and March. The dolphin calls and unknown click trains were significantly more frequent at night. In contrast, marginal diel changes in killer whale calls were detected. Our results suggest that the majority of cetaceans utilize Nemuro Strait at night during the ice‐free period, and we provide new insights into the habitat use and diversity of marine mammals in the Strait. [ABSTRACT FROM AUTHOR]

The article reports that the fecal samples from cetaceans have been collected using scat-detecting dogs. Topics include examines the field operations were undertaken with a several meter rigid-hulled Zodiac with a custom-made bow pulpit, providing an elevated platform for the sampler; and considered the behaviors are typical for pilot whales during midday in Hawaiian waters.

Scientific information is vital to the conservation of cetaceans and the management of whale‐watching activities. The southern coastal waters of Sri Lanka are near a narrow continental shelf and biologically abundant in cetacean species. Although the occurrence of cetaceans has been investigated in certain waters of Sri Lanka, few surveys have been conducted along the southern coast. To fill this gap, we conducted boat‐based surveys from January to May 2017 to investigate the occurrence, diversity, and behavior of cetaceans in the waters off Mirissa, covering a survey area of 788.9 km2. During 55 survey days, we recorded a total of 242 cetacean sightings and identified at least 9 species (3 mysticetes and 6 odontocetes). The blue whale was the most common mysticete species (167 of 174 mysticete encounters), followed by the Omura's whale (4 of 174) and Bryde's whale (3 of 174). The spinner dolphin was the most common odontocete species (28 of 68 odontocete encounters), followed by the sperm whale (18 of 68), common bottlenose dolphin (13 of 68), short‐finned pilot whale (5 of 68), melon‐headed whale (2 of 68), and killer whale. Blue whales and sperm whales exhibited a clear preference for outer shelf and high slope areas, and blue whales were observed feeding along these waters. The present study provides near‐baseline information on cetacean occurrence and diversity in whale‐watching waters off southern Sri Lanka, and highlights the urgent need for proper management strategies for whale‐watching activities. [ABSTRACT FROM AUTHOR]

Recording continued until (1) at least 15 min of continuous recording was completed, (2) the target whale was judged to be too far away to accurately calculate IPI based on the amplitude of the clicks, or (3) other whales appeared to be closer to the hydrophone array or louder than the target whale. Photo-ID of the whales recorded, and the fact that whales at Kaikoura are almost always alone and generally spaced >1 nmi apart (Childerhouse et al., 1995), ensured that acoustic recordings could be confidently assigned to particular whales. Sperm whale clicks have a characteristic multipulse structure, which results from how the clicks are generated and the unique structure of the sperm whale head (Møhl et al., 2000; Norris & Harvey, 1972). [Extracted from the article]

The Gulf of Alaska is an important habitat for a diverse array of marine mammals, many of which were severely depleted by historical whaling. To study current cetacean distributions in this region, passive acoustic monitoring was used to detect species-specific call types between 2011 and 2015 at five locations spanning the continental shelf, slope, and offshore seamounts. Spatial and temporal detection patterns were examined for nine species to compare differences in behavior and habitat use. Mysticetes showed seasonal increases in calling that indicated possible behavioral shifts between feeding and breeding in blue (Balaenoptera musculus), fin (B. physalus), and humpback (Megaptera novaeangliae) whales, and matched known migration timing of gray whales (Eschrichtius robustus). Interannual changes in blue and fin whale calling may relate to the marine heat wave that began in 2013 and lasted through the end of the monitoring period. Odontocete detections revealed unique spatial distributions, with killer whales (Orcinus orca) most common on the continental shelf and sperm whales (Physeter macrocephalus) most common on the continental slope, where detections occurred year-round. Beaked whales showed both spatial and temporal separation: Baird's beaked whale (Berardius bairdii) detections were highest at Quinn Seamount in the spring, Cuvier's (Ziphius cavirostris) at Pratt Seamount in winter, and Stejneger's (Mesoplodon stejnegeri) on the continental slope in the fall. The year-round presence of many species highlights the ecological importance of the Gulf of Alaska and the spatiotemporal information reported here should inform future conservation efforts. [ABSTRACT FROM AUTHOR]

Large diversity and abundance of cetacean species occur along the Brazilian outer continental shelf and slope waters. In the present study, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes in skin biopsies of ten odontocete species (Delphinidae and Physeteridae) to assess the intra- and inter-specific patterns in the use of resources along the region. Our isotopic analysis allowed us to identify two potential subpopulations of Stenella frontalis. High core isotopic niche overlap between S. frontalis from the southern range of the study area and Delphinus delphis, especially in spring, suggested that they share similar resources and rely on spatiotemporal segregation to achieve niche differentiation and to minimize competition. Our isotopic data also pointed to high similarity among Tursiops truncatus, S. frontalis, and Globicephala melas in the use of resources. Steno bredanensis had the highest δ15N and δ13C, which agrees with its occurrence in neritic waters. S. longirostris showed consistently low δ15N values, indicating that they feed at relatively lower trophic levels, and lack of niche overlap with most delphinid species, except S. attenuata. Orcinus orca and G. melas had very similar δ13C and δ15N values, that were consistent with feeding in offshore waters. δ13C and δ15N in Physeter macrocephalus suggested that individuals feed on similar trophic levels, but over a wide spatial range. The analyses of stable isotopes in skin biopsies helped us to refine our knowledge about the intra-specific resource and habitat use, ecological niches, and the trophic interactions amongst co-occurring cetaceans from the oceanic waters of the subtropical western South Atlantic. [ABSTRACT FROM AUTHOR]

As Arctic seas rapidly change with increased ocean temperatures and decreased sea ice extent, traditional Arctic marine mammal distributions may be altered, and typically temperate marine mammal species may shift poleward. Extant and seasonal odontocete species on the continental shelves of the Bering and Chukchi Seas include killer whales (Orcinus orca), sperm whales (Physeter microcephalus), beluga whales (Delphiapterus leucas), harbor porpoises (Phocoena phocoena), and Dall's porpoises (Phocoenoides dalli). Newly documented, typically temperate odontocete species include Risso's dolphins (Grampus griseus) and Pacific white-sided dolphins (Lagenorhynchus obliquidens). Until recently, recording constraints limited sampling rates, preventing the acoustic detection of many of these high frequency-producing (> 22 kHz) species in the Arctic seas. Using one of the first long-term datasets to record frequencies up to 50 kHz in these waters, clicks, buzzes, and whistles have been detected, classified, and paired with environmental data to explore which variables best parameterize habitat preference. Typically temperate species were associated temporally with cold Bering Sea Climate Regimes in tandem with negative Pacific Decadal Oscillations. Typically Arctic species' strongest explanatory variables for distribution were largely species and site specific. Regardless of species, however, the environmental cues (e.g. percent ice cover or zooplankton community structure) marine mammals use for locating viable habitat space are ones that will change as temperatures increase. This 10-year dataset documents the current state and tracks recent dynamics of odontocetes and their habitats along the Pacific Arctic Corridor to contribute to ongoing discussions about future Arctic conditions. [ABSTRACT FROM AUTHOR]

To date in Sri Lankan waters, there has been limited research on Killer Whales. These animals have been recorded almost all around the island, except in the northernmost waters and in Palk Bay. The highest observed concentrations are from the northeastern, south/southwestern and northwestern coastal waters of Sri Lanka. These have come from both opportunistic observations and dedicated scientific surveys. Seasonal trends in sightings in some locations suggest fairly consistent occupancy. Transient Killer Whales have been documented attacking/killing Sperm Whales from many geographic locations around the world. To date, there is only one published account of Killer Whales feeding in Sri Lankan waters. Our paper presents, for the first time, field observations of Killer Whales preying upon superpods of Sperm Whales in the waters off the Kalpitiya Peninsula (eastern half of the Gulf of Mannar), northwestern Sri Lanka. The incidents took place on two separate occasions during the months of March and April, 2017. [ABSTRACT FROM AUTHOR]

In the California Current off the United States West Coast, there are three offshore cetacean species that produce narrow-band high frequency (NBHF) echolocation pulses: Dall's porpoise (Phocoenoides dalli) and two species of Kogia. NBHF pulses exist in a highly specialized acoustic niche thought to be outside the hearing range of killer whales and other potential mammal-eating odontocetes. Very little is known about the dwarf and pygmy sperm whales (K. sima and K. breviceps), including their NBHF pulse characteristics. This paper presents a multivariate clustering method using data from unmanned drifting acoustic recorders and visually verified porpoise recordings to discriminate between probable porpoise and Kogia clicks. Using density clustering, this study finds three distinct clusters whose geographic distributions are consistent with the known habitat range for Kogia and Dall's porpoise. A Random Forest classification model correctly assigned 97% of the clicks to their cluster. Visually verified Dall's porpoise clicks from towed hydrophones were strongly associated with one of the clusters, while a second cluster tended to be outside the geographic range of Dall's porpoise and unlike the Dall's porpoise cluster. These clicks, presumed to be made by Kogia, exhibited greater spectral variance than previous Kogia echolocation studies. It is possible that the structure of Kogia NBHF pulses may not be as stereotypical as previously described. [ABSTRACT FROM AUTHOR]

Marine predators feeding on fisheries catches directly on the fishing gear, a behaviour termed "depredation", has emerged as a major human-wildlife conflict globally, often resulting in substantial socio-economic and ecological impacts. This study investigated the extent of this conflict in commercial Patagonian toothfish (Dissostichus eleginoides) fisheries across subantarctic waters where both killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) feed on toothfish caught on longline hooks. Using long-term datasets from six major fishing areas, from southern Chile to the Indian Ocean sector of the Southern Ocean, statistical models were developed to quantify the catch removals due to whale depredation interactions. The results indicated that these removals were large, totalling more than 6600 t of toothfish between 2009 and 2016 with an annual mean of 837 t [95% CI 480–1195 t], comprised of 317 t [232–403 t] and 518 t [247–790 t] removed by killer whales and sperm whales, respectively. Catch removals greatly varied between areas, with the largest estimates found at Crozet, where on average 279 t [179–379 t] of toothfish per year, equivalent to 30% [21–37%] of the total catches. Together, these findings provide metrics to assess the impacts of depredation interactions on the fishing industry, whale populations, fish stocks and associated ecosystems. With an estimated $15 M USD worth of fish depredated every year, this study highlights the large geographic scale and economic significance of the depredation issue and its potential to compromise the viability of some toothfish fisheries which are the primary socio-economic activity in subantarctic regions. [ABSTRACT FROM AUTHOR]

Toothed whales (odontocetes) feeding on fish caught on hooks in longline fisheries is a growing issue worldwide. The substantial impacts that this behaviour, called depredation, can have on the fishing economy, fish stocks and odontocetes populations, raise a critical need for mitigation solutions to be developed. However, information on when, where and how odontocete depredation occurs underwater is still limited, especially in demersal longline fisheries (fishing gear set on the seafloor). In the present study, we investigated depredation by killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) on demersal longlines in the French Patagonian toothfish fishery (Southern Ocean). Using a combination of animal-borne behavioural and longline-attached data loggers, we demonstrated that both species are able to depredate longlines on the seafloor. This study, therefore, suggests that odontocetes whales–longline interaction events at depth may be unrecorded when assessing depredation rates from surface observations during hauling phases only. This result has implications for the management of fisheries facing similar depredation issues as underestimated depredation rates may result in unaccounted fish mortality in fish-stock assessments. Therefore, while further research should be conducted to assess the extent of deep-sea whale–longline interaction events during soaking, the evidence that depredation can occur at any time during the whole fishing process as brought out by this study should be considered in future developments of mitigation solutions to the issue. [ABSTRACT FROM AUTHOR]

Phthalates are used in plastics, found throughout the marine environment and have the potential to cause adverse health effects. In the present study, we quantified blubber concentrations of 11 phthalates in 16 samples from stranded and/or free-living marine mammals from the Norwegian coast: the killer whale (Orcinus orca), sperm whale (Physeter macrocephalus), long-finned pilot whale (Globicephala melas), white-beaked dolphin (Lagenorhynchus albirostris), harbour porpoise (Phocoena phocoena), and harbour seal (Phoca vitulina). Five compounds were detected across all samples: benzyl butyl phthalate (BBP; in 50 % of samples), bis(2-ethylhexyl) phthalate (DEHP; 33 %), diisononyl phthalate (DiNP; 33 %), diisobutyl phthalate (DiBP; 19 %), and dioctyl phthalate (DOP; 13 %). Overall, the most contaminated individual was the white-beaked dolphin, whilst the lowest concentrations were measured in the killer whale, sperm whale and long-finned pilot whale. We found no phthalates in the neonate killer whale. The present study is important for future monitoring and management of these toxic compounds. [Display omitted] • Blubber concentrations of 11 phthalates were quantified in 16 marine mammals from Norway. • Five compounds were detected across all samples: BBP, DEHP, DiNP, DiBP and DOP. • Highest concentrations were detected in the white-beaked dolphin. • Lowest concentrations were measured in the killer whale, sperm whale and long-finned pilot whale. • No phthalates were detected in a neonate killer whale. [ABSTRACT FROM AUTHOR]

The article offers information on a study of cookiecutter shark bite wounds on cetaceans of the Gulf of Mexico (GOM). Several cetacean species with cookiecutter shark bite wounds were observed in GOM which include beaked whale, sperm whale (Physeter macrocephalus), and killer whale (Orcinus orca). Also provided are stable isotope ratios for sperm whales, cookiecutter sharks, and sperm whale preys.

Larger mass strandings of open ocean odontocetes (toothed whales) of 10+ animals are examined with a compilation of 710 worldwide events. Six species form 96% of events (false killer, long-finned pilot, melon-headed, short-finned pilot, sperm and white whales), with beaked, killer, and pygmy killer whales forming 4%. Site type was determined for 630 events - three-quarters (76%) are in bays, 14% in shallow topographically complex areas (estuarine environments, straits, keys, reef and coastal lagoons), 8% on relatively unindented coasts, with ice entrapment (of killer whales) and miscellaneous categories being 2%. For the 76% of events in bays, sites with headland-bay character make up 42%, spit-bays 20% (even though there are only four of them), indented bays 9% and unspecified bay types 5%. Headland-bays and spit-bays become stranding sites through the properties endowed them by their mechanisms of formation and maintenance, but these mechanisms differ greatly for the two. Breakwaters, groyne series, tides, partial burial, and violent storms also appear as themes. Nearshore slopes are less than 1° for 94 of 105 sites having bathymetry information, with only two reaching or exceeding 3°. Some types of potential stranding sites can be identified by simple quantitative specifications for planform, sediment size, and seabed slope, although strandings will not necessarily occur there. There is an indication that larger strandings are globally correlated with areas of higher oceanic primary productivity near landmasses and oceanic islands, but quantitative studies are needed to clarify any such possible relationship. There is also an indication that larger strandings are associated with plate tectonics, with few events being seen on the steeper swell resistant active western margins of South America and South Island (New Zealand) in particular. In contrast several larger events are recorded for the relatively older passive margins of the south-eastern sides of these two landmasses, putatively because waves and swell have had time to construct stranding sites on them. Similarly, few larger events are seen for steeper shores adjacent to coastal highlands, such as those of South Africa and Brazil. These observations indicate previously unsuspected relations between the phenomenon of odontocete mass strandings and global scale earth and ocean processes, but they are essentially hypotheses in need of more quantitative examination. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Animal behavioural interactions with plastic litter remain poorly understood. • Cetacean species were found to actively interact with single-use plastics worldwide. • Play with plastic litter might cause serious threats. • Measures to reduce marine plastics are available but insufficient. • More policies and awareness are needed to reduce SUPs in the environment. [ABSTRACT FROM AUTHOR]