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The blue whale is an endangered and globally distributed species of baleen whale with multiple described subspecies, including the morphologically and genetically distinct pygmy blue whale. North Atlantic and North Pacific populations, however, are currently regarded as a single subspecies despite being separated by continental land masses and acoustic call differences. To determine the degree of isolation among the Northern Hemisphere populations, 14 North Pacific and 6 Western Australian blue whale nuclear and mitochondrial genomes were sequenced and analysed together with 11 publicly available North Atlantic blue whale genomes. Population genomic analyses revealed distinctly differentiated clusters and limited genetic exchange among all three populations, indicating a high degree of isolation between the Northern Hemisphere populations. Nevertheless, the genomic and mitogenomic distances between all blue whale populations, including the Western Australian pygmy blue whale, are low when compared to other inter‐subspecies distances in cetaceans. Given that the Western Australian pygmy blue whale is an already recognised subspecies and further supported by previously reported acoustic differences, a proposal is made to treat the two Northern Hemisphere populations as separate subspecies, namely Balaenoptera musculus musculus (North Atlantic blue whale) and Balaenoptera musculus sulfureus (North Pacific blue whale). Furthermore, a first molecular viability assessment of all three populations not only found a generally high genomic diversity among blue whales but also a lack of alleles at low frequency, non‐neutral evolution and increased effects of inbreeding. This suggests a substantial anthropogenic impact on the genotypes of blue whales and calls for careful monitoring in future conservation plans. [ABSTRACT FROM AUTHOR]

The article "Predation of a Sperm Whale by Killer Whales in Guanaja, Honduras" published in Aquatic Mammals discusses a rare event witnessed by recreational anglers involving three killer whales attacking a sperm whale in the Caribbean Sea. The study highlights the complex predator-prey dynamics between killer whales and sperm whales in the Caribbean, an area that remains relatively understudied. The event, documented through photos and videos, provides valuable insights into the feeding ecology and behaviors of killer whales in tropical waters, shedding light on their potential role as generalist hunters in the region. [Extracted from the article]

The article in Marine Mammal Science discusses the sequences of a possible distress call of a juvenile gray whale found in a shallow lagoon within the Gulf of California. Gray whales use sound to communicate, with various sounds associated with different activities. The study reports a new tonal call type, S10, possibly produced by a juvenile gray whale, which was detected in sequences along with known S1 calls. The authors speculate that the distress calls or mixed sequences could serve as contact or distress calls, especially in the context of whales visiting shallow areas where they could potentially strand. [Extracted from the article]

The article in Marine Mammal Science discusses the southbound migration of satellite-tagged pygmy blue whales from the Savu Sea in Indonesia to subantarctic waters. The study tracked two pygmy blue whales, showing their movements from Indonesia to Australian waters and the subantarctic region. The research highlights the extended habitat range of Australian pygmy blue whales and suggests the need for more satellite tagging to confirm migratory routes. The study also acknowledges the support of various individuals and organizations in conducting the research. [Extracted from the article]

Blue (Balaenoptera musculus) and fin (B. physalus) whales are prominent species in the California Current Ecosystem (CCE) using the area for migration and foraging. Blue whales migrate between tropical wintering grounds and higher latitude foraging grounds in the CCE, whereas fin whales may remain there year-round. We used Argos tracks of 182 blue (mean duration: 78 days) and 98 fin (mean duration: 35 days) whales tagged from 1994-2018 along the U.S. West Coast to examine residence time and occupancy in U.S. Navy training and testing areas. Bayesian hierarchical switching state-space model locations calculated from Argos tracks were used to provide residence time and proportion of tracking duration within each Navy area. We also calculated relative occupancy isopleths from the state space models, for both directed and non-directed movement, to assess spatial use of Navy areas. We then used generalized linear mixed models and beta regression to examine relationships between Navy area use and covariates, including six climate indices. Point Mugu Sea Range (PMSR) was the most heavily used Navy area by both species in terms of whale numbers, followed by the Southern California Range Complex (SOCAL). Residence time was longest in PMSR for blue whales and in the Northwest Training and Testing Study Area (NWTT) for fin whales. Blue whale use in PMSR was greater in summer versus autumn and for whales tagged in Southern versus Central California. Proportion of tracking duration decreased in all areas with increasing values of the Oceanic Niño Index (ONI), and in PMSR, with increasing values of the North Pacific Gyre Oscillation. Fin whale residence time was longer in PMSR during summer than winter or spring and decreased with increasing values of Habitat Compression Index and ONI. Proportion of tracking duration for fin whales was greatest in summer in PMSR and in winter in SOCAL and NWTT. Overlap of directed and non-directed movement was greatest in PMSR for both species. This assessment of blue and fin whale residence time and occupancy in Navy areas improves our understanding of potential threats these animals face, not only from military activities in Navy areas, but throughout the CCE. [ABSTRACT FROM AUTHOR]

\nHIGHLIGHTSOver recent decades, the feeding strategies of the blue whale (Balaenoptera musculus) in the northern Chilean Patagonia have been studied mainly through visual observation and anatomical dissection, with limited direct behavioral analyses and measurements of prey distribution due to the difficulty of sampling. Here, we investigated the foraging ecology of this species during six annual research cruises (2014–2019) in the northern Chilean Patagonia, an important feeding and nursery area. We deployed 28 sound and movement recording tags (DTAGs), attached by suction cups, to measure fine-scale behaviors of this species. In addition, from 2016 to 2019, prey density and distribution were simultaneously recorded with tag data utilizing a scientific echosounder. A total of 949 foraging dives and 3,183 feeding events were detected from movement sensors throughout more than 190 hr of data, during both day and nighttime. Blue whales exhibited both shallow and deep foraging events utilizing different strategies in response to changing conditions of prey depth and density, with foraging dives recorded continuously for the whole duration of the deployments. Whales showed a higher feeding rate at night as they foraged on shallow and dispersed krill, but they exhibited a higher rate of foraging events per dive during the day, as they foraged on deep and dense krill patches. The whales used less energetically costly maneuvers when foraging near the surface, with lower values of pitch and speed. Both strategies are consistent with optimal foraging theory, as the whales minimizing energetic costs associated with feeding while simultaneously maximizing energy intake. These results provide valuable insights into the behavioral and foraging ecology of blue whales to promote specific conservation plans in the northern Chilean Patagonia.Blue whales in the northern Chilean Patagonia showed adaptive foraging behavior by aligning their feeding depth with the location of peak krill density when feeding in deep patches. By focusing on the densest aggregation of prey, blue whales optimized energy intake during each feeding lunge. These results underscore the importance of accounting for prey density, along with factors such as prey depth and diving behavior patterns, when evaluating optimal foraging models for whale feeding strategies. [ABSTRACT FROM AUTHOR]

Climate change-induced habitat alterations in the Arctic Ocean are expected to affect spatial and temporal occurrence patterns of seasonally migrating baleen whale species, leading to poleward range shifts and prolonged stays in Arctic waters. The aim of this study was to investigate occurrence patterns of blue (Balaenoptera musculus musculus) and fin (B. physalus) whales in Fram Strait, a summering habitat and historic whaling ground for both species. Passive acoustic monitoring data were collected between 2012 and 2021 at eight different mooring positions in eastern and central Fram Strait. These data were initially analyzed for the acoustic presence of blue and fin whales. Afterwards, the environmental impact on acoustic occurrences and the potential temporal expansion of acoustic presence periods were investigated. Blue whale acoustic presence showed a clear seasonality, with most calls being detected from July to October. Additionally, sporadic blue whale calls were detected in winter in three years on one or a few consecutive days. Fin whale acoustic presence varied between years, with peak presence from mid-summer through autumn, moderate presence in winter, and sporadic presence in spring. Random forest models suggested that zooplankton mass content, sea surface temperature and day of the year influenced blue whale acoustic presence, while fin whale acoustic presence was impacted by day of the year. For both species, no temporal trend in the onset and offset of acoustic presence periods was found. Our findings highlight eastern Fram Strait as key marine mammal habitat, probably serving as a feeding ground. Occasional (blue whales) and regular (fin whales) acoustic presence during the winter months further supports the hypothesis of complex migration behaviors in both species. [ABSTRACT FROM AUTHOR]

Climate change poses severe risks to the survival of many whale populations, whose habitats and migration patterns are affected by environmental changes. To detect these whales effectively, especially in deep-sea environments, we need to use AI-based techniques to handle the acoustic diversity and variability of different species. However, current methods for whale detection are based on pre- and post-processing steps that reduce their efficiency and generalizability. To address this issue, we present DeepWhaleNet, a novel deep-learning model that automates whale detection in Underwater Passive Acoustic Monitoring datasets. DeepWhaleNet simplifies the detection process by extracting relevant features from raw log-power spectrograms and helps protect these threatened species by supporting conservation efforts. Our model uses a larger short-time Fourier transform as input and a custom ResNet-18 architecture for classification, which enables it to separate whale sounds from noise and capture their temporal and spectral characteristics. We evaluate the performance of DeepWhaleNet and show that it surpasses state-of-the-art methods, achieving an 8.3% improvement in the F-1 score and 21% higher average precision of binary relevance than the baseline method. Moreover, our model demonstrates its versatility and suitability for species-specific retrieval problems through an ablation study on multi-label retrieval problems and a 99.1% recall for Blue Whales. [ABSTRACT FROM AUTHOR]

Data collection facilitated by remotely piloted aircraft (RPA) has proven to be revolutionary in many disciplines including for research in extreme environments. Here we assess current use and utility of small multirotor remotely piloted aircraft (RPAs) for the challenging role of facilitating ship-based cetacean research in Antarctica. While such aircraft are now used routinely in sheltered environments in and off Antarctica, a comprehensive literature review found that RPA-mediated cetacean research conducted from ships at sea and outside of the Antarctic Peninsula region was relatively uncommon. In order to determine the potential utility of ship-based multirotor RPA operations for cetacean research, we repeatedly deployed small RPAs during a multidisciplinary research voyage in maritime East Antarctica to collect scientific data contributing to an understanding of krill and krill predator interactions. RPA flight metrics (duration, height, length, speed, distance from ship, battery drainage, satellites acquired) were compared to ship underway environmental sampling data. At a mean duration of 12 minutes, these 139 RPA flights were relatively short yet adequate to achieve the science intended, namely a range of cetacean related data streams including photogrammetry, photo identification, behavioural observations and whale blow sampling in addition to water sampling and collection of general scenic imagery. RPA flight operations were constrained by wind speed but not by air temperature with flights undertaken throughout the full range of air temperatures experienced (down to -9.5°C) but not throughout the full range of wind speeds experienced. For a 12-minute flight duration, battery drainage was around 60% indicating that the RPAs were rarely pushed to their operational limit. There was little evidence that the cold impacted RPA lithium battery performance with estimated maximum flight time within approximately 10% of expected flight time for the RPA platforms most used. Whist small multirotor RPAs are rarely applied to cetacean related research in maritime East Antarctica, we demonstrate their value and potential to deliver data critical to address knowledge gaps that challenge the effective management of both krill and their predators. [ABSTRACT FROM AUTHOR]

The sequencing of a kidney sample (KW2013002) from a stranded Megaptera novaeangliae (Humpback whale) calf is the first chromosome-level reference genome for this species1. The calf, a 457 cm and 2,500 lbs male, was found stranded in Hawai'i Kai, HI, in 2013 and was marked as abandoned/orphaned. In 2023, 1 g of kidney was sequenced with PacBio long-read DNA sequencing, chromatin conformation capture (Hi-C), RNA sequencing, and mitochondrial sequencing to comprehensively characterize the genome and transcriptome of M. novaeangliae. Data validation includes a synteny analysis, mitochondrial annotation, and a comparison of BUSCO scores (scaffold v. reference genome and Balaenoptera musculus (Blue whale) v. M. novaeangliae). BUSCO analysis was performed on an M. novaeangliae scaffold-level assembly to determine genomic completeness of the reference genome, with a scaffold BUSCO score of 91.2% versus a score of 95.4%. Synteny analysis was performed using the B. musculus genome as comparison to determine chromosome-level coverage and structure. Further, a time-based phylogenetic tree was constructed using the sequenced data and publicly available genomes. [ABSTRACT FROM AUTHOR]

Blue whales (Balaenoptera musculus) are the largest living animal and, like other baleen whales, became endangered due to whaling. Here, we used population genomics to infer the number, distribution and other characteristics of subspecies and populations. We used the largest DNA dataset in blue whales, both in terms of genomic markers (16,661 SNPs and mtDNA) and geographic coverage (n = 276 for SNPs; n = 531 for mtDNA). We found greatest divergence among the eastern Pacific, Indo‐western Pacific and Antarctic blue whales. There were indications that natural selection in different environments promoted divergence among these groupings. Within these regions, there was divergence between the eastern North and eastern South Pacific, and among the eastern Indian Ocean, the western South Pacific and the northern Indian Ocean. There was no divergence within the Antarctic. These findings are consistent with the current classification of Antarctic and Indo‐western Pacific blue whales in the Southern Hemisphere as different subspecies but call into question the subspecies taxonomy of eastern Pacific blue whales. The study shows that opposite breeding seasons on either side of the equator do not necessarily inhibit connectivity across the equator, and reinforces that population structure needs to be well understood to conserve the diversity within species. [ABSTRACT FROM AUTHOR]

Renowned marine mammal scientist Roger Payne, who passed away in 2023 at the age of 88, is best known for his work on humpback whale songs, which helped change public perception of whales. His research on live whales at sea and his recordings of humpback songs played a significant role in the environmental conservation movement of the early 1970s. Payne's contributions extended beyond whales, as he conducted groundbreaking research on other species and was known for his ability to merge science, art, and music. The text also highlights the experiences and mentorship of Roger and Katy Payne, emphasizing their generosity, wisdom, and dedication to conservation. The authors express gratitude for the opportunities and knowledge gained through their association with the Paynes. [Extracted from the article]

Understanding the drivers of population abundance and distribution is fundamental to ecology and key to informing conservation actions, particularly in endangered species like blue whales (Balaenoptera musculus). Historically, some Eastern North Pacific blue whales have aggregated in the Gulf of California (GoC) each winter. Using photo‐identification data collected around Loreto Bay from 1984 to 2020, we analyzed 453 sightings histories using mark‐recapture models. Estimated apparent survival (including permanent emigration) decreased from 0.991, 95% CI [0.977, 0.997] in 1985 to 0.889, 95% CI [0.807, 0.939] in 2019. The estimated number of whales using the study area declined from 96 whales, 95% CI [50, 254] in 2012 to 13 whales, 95% CIs [12, 23 and 12, 28] in 2018 and 2019. Abundance of the whole Eastern North Pacific population is slowly increasing, so our results likely reflect declining usage of the GoC. Linear models found a relationship between the number of whales in the GoC and the difference in sea surface temperature between the study area and the Costa Rica Dome wintering area, suggesting that environmental variation could explain variation in blue whale numbers in the GoC. These results highlight the importance of tracking population dynamics as changing environmental conditions affect the range and distribution of populations. [ABSTRACT FROM AUTHOR]

We explore the utility of estimating the density of calls of baleen whales for better understanding acoustic trends over time. We consider as a case study stereotyped 'song' calls of Antarctic blue whales (Balaenoptera musculus intermedia) on their Antarctic feeding grounds over the course of a year-long, continuous recording from 2014. The recording was made in the Southern Ocean from a deep-water autonomous hydrophone moored near the seafloor in the Eastern Indian sector of the Antarctic. We estimated call density seasonally via a Monte-Carlo simulation based on the passive sonar equation, and compared our estimates to seasonal estimates of detection rate, which are commonly reported in acoustic studies of Antarctic blue whales. The resulting seasonal call densities at our Antarctic sitewere strongly influenced by seasonally varying noise levels, which in turn yielded seasonal differences in detection range. Incorporating the seasonal estimates of detection area into our analysis revealed a pattern of call densities in accord with historic (nonacoustic) knowledge of Antarctic blue whale seasonal distribution and migrations, a pattern that differed from seasonal detection rates. Furthermore, our methods for estimating call densities produced results that were more statistically robust for comparison across sites and time and more meaningful for interpretation of biological trends compared to detection rates alone. These advantages came at the cost of a more complex analysis that accounts for the large variability in detection range of different sounds that occur in Antarctic waters, and also accounts for the performance and biases introduced by automated algorithms to detect sounds. Despite the additional analytical complexities, broader usage of call densities, instead of detection rates, has the potential to yield a standardized, statistically robust, biologically informative, global investigation of acoustic trends in baleen whale sounds recorded on single hydrophones, especially in the remote and difficult to access Antarctic. [ABSTRACT FROM AUTHOR]

Simple Summary: The Galapagos Marine Reserve supports cetaceans such as blue whales by providing essential foraging areas and resting areas. From 2021 to 2023, a study utilized satellite tags on 16 blue whales to monitor their movements and gain insights into their interactions with the marine environment. This involved the identification of their feeding grounds, indicated by chlorophyll levels, surface water temperature (SST), and ocean productivity. The study revealed that blue whales prefer areas with presumed increased prey abundance, cooler water temperatures, and specific underwater features such as ridges that likely enhance favored food sources. Most of the tagged whales remained in the Galapagos, particularly near Isabela Island, where there is an elevated risk of collisions with boats due to increased marine traffic. Some whales ventured into Ecuador's waters, and one even traveled to Peru. In 2023, an intense El Niño event led to changes in water temperatures and food availability, significantly impacting whale habitats. This research contributes to efforts to protect whales from ship collisions and understand and adapt to changes in their migration patterns due to climate variations. The Galapagos Marine Reserve is vital for cetaceans, serving as both a stopover and residency site. However, blue whales, occasionally sighted here, exhibit poorly understood migratory behavior within the Galapagos and the broader Eastern Tropical Pacific. This study, the first to satellite tag blue whales in the Galapagos (16 tagged between 2021 and 2023), explored their behavior in relation to environmental variables like chlorophyll-a concentration, sea surface temperature (SST), and productivity. Key findings show a strong correlation between foraging behavior, high chlorophyll-a levels, productivity, and lower SSTs, indicating a preference for food-rich areas. Additionally, there is a notable association with geomorphic features like ridges, which potentially enhance food abundance. Most tagged whales stayed near the Galapagos archipelago, with higher concentrations observed around Isabela Island, which is increasingly frequented by tourist vessels, posing heightened ship strike risks. Some whales ventured into Ecuador's exclusive economic zone, while one migrated southward to Peru. The strong 2023 El Niño–Southern Oscillation event led to SST and primary production changes, likely impacting whale resource availability. Our study provides crucial insights into blue whale habitat utilization, informing adaptive management strategies to mitigate ship strike risks and address altered migration routes due to climate-driven environmental shifts. [ABSTRACT FROM AUTHOR]

"Red Leviathan: The Secret History of Soviet Whaling" by Ryan Tucker Jones explores the complex history of Soviet whaling, highlighting the intertwined fates of the Soviet Union and whale populations. Jones uncovers the unique characteristics of Soviet whaling, including its acceleration in the second half of the twentieth century and its motivations rooted in historical grievances and revenge. The book also delves into the contradictions of Soviet whaling, where an appreciation for whales as sentient beings coexisted with the commitment to killing them. Ultimately, Jones raises thought-provoking questions about the concept of genocide in the context of human exploitation of nonhuman nature, sparking further debate and discussion in scholarly circles. [Extracted from the article]

Effective protection of highly mobile and data-poor species constitutes a great challenge amid growing ocean exploitation and use. Blue whales and bowhead whales in the North-East Atlantic face several threats, such as climate change, ship strikes, pollution, and entanglement in fishing gear. Consequently, the OSPAR ("Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic") Commission recognised their need for protection and included them on the OSPAR List of Threatened and/or Declining Species. Two actions to protect these endangered species that OSPAR Contracting Parties have agreed on are (i) identifying areas that play an essential role in the species' life cycle—subsequently called key habitats, and (ii) ensuring that those key habitats are covered by OSPAR marine protected areas (MPAs). In addition, OSPAR has committed to expanding its network of MPAs and other effective area-based conservation measures by 2030 to cover at least 30% of the OSPAR maritime area (termed the 30 × 30 target) from today's approx. 11%. In this paper, we present the results of modelling key habitats for the bowhead and blue whales in the North-East Atlantic, including Arctic waters. Due to the sparse data situation for these species, we apply presence-only modelling methods. As this method can, in principle, produce somewhat biased results, we recommend that systematic, regular surveys on these species in Arctic waters be significantly intensified for future analyses to overcome the data paucity and allow using presence–absence/count data modelling approaches. Key habitats of blue whales were identified between Iceland and Svalbard, extending to the Azores. For bowhead whales, key habitats were identified in the Fram Strait. However, our findings show that only 11.8% of blue whale key habitats and 4.1% of bowhead whale key habitats are currently covered by OSPAR MPAs. To protect 30% of key habitats for these species in the most efficient way, our analyses suggest that suitable areas to designate new OSPAR MPAs are located around the Azores for blue whales and in the Fram Strait for bowhead whales. With these additional MPAs, OSPAR would substantially improve the protection of the two endangered species and, at the same time, progress towards its 30 × 30 target. [ABSTRACT FROM AUTHOR]

The study of animal sounds in biology and ecology relies heavily upon time–frequency (TF) visualisation, most commonly using the short‐time Fourier transform (STFT) spectrogram. This method, however, has inherent bias towards either temporal or spectral details that can lead to misinterpretation of complex animal sounds. An ideal TF visualisation should accurately convey the structure of the sound in terms of both frequency and time, however, the STFT often cannot meet this requirement. We evaluate the accuracy of four TF visualisation methods (superlet transform [SLT], continuous wavelet transform [CWT] and two STFTs) using a synthetic test signal. We then apply these methods to visualise sounds of the Chagos blue whale, Asian elephant, southern cassowary, eastern whipbird, mulloway fish and the American crocodile. We show that the SLT visualises the test signal with 18.48%–28.08% less error than the other methods. A comparison between our visualisations of animal sounds and their literature descriptions indicates that the STFT's bias may have caused misinterpretations in describing pygmy blue whale songs and elephant rumbles. We suggest that use of the SLT to visualise low‐frequency animal sounds may prevent such misinterpretations. Finally, we employ the SLT to develop 'BASSA', an open‐source, GUI software application that offers a no‐code, user‐friendly tool for analysing short‐duration recordings of low‐frequency animal sounds for the Windows platform. The SLT visualises low‐frequency animal sounds with improved accuracy, in a user‐friendly format, minimising the risk of misinterpretation while requiring less technical expertise than the STFT. Using this method could propel advances in acoustics‐driven studies of animal communication, vocal production methods, phonation and species identification. [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]

Social information is predicted to enhance the quality of animals' migratory decisions in dynamic ecosystems, but the relative benefits of social information in the long-range movements of marine megafauna are unknown. In particular, whether and how migrants use nonlocal information gained through social communication at the large spatial scale of oceanic ecosystems remains unclear. Here we test hypotheses about the cues underlying timing of blue whales' breeding migration in the Northeast Pacific via individual-based models parameterized by empirical behavioral data. Comparing emergent patterns from individual-based models to individual and population-level empirical metrics of migration timing, we find that individual whales likely rely on both personal and social sources of information about forage availability in deciding when to depart from their vast and dynamic foraging habitat and initiate breeding migration. Empirical patterns of migratory phenology can only be reproduced by models in which individuals use long-distance social information about conspecifics' behavioral state, which is known to be encoded in the patterning of their widely propagating songs. Further, social communication improves pre-migration seasonal foraging performance by over 60% relative to asocial movement mechanisms. Our results suggest that long-range communication enhances the perceptual ranges of migrating whales beyond that of any individual, resulting in increased foraging performance and more collective migration timing. These findings indicate the value of nonlocal social information in an oceanic migrant and suggest the importance of long-distance acoustic communication in the collective migration of wide-ranging marine megafauna. [ABSTRACT FROM AUTHOR]

Background: Accurate predictions of animal occurrence in time and space are crucial for informing and implementing science-based management strategies for threatened species. Methods: We compiled known, available satellite tracking data for pygmy blue whales in the Eastern Indian Ocean (n = 38), applied movement models to define low (foraging and reproduction) and high (migratory) move persistence underlying location estimates and matched these with environmental data. We then used machine learning models to identify the relationship between whale occurrence and environment, and predict foraging and migration habitat suitability in Australia and Southeast Asia. Results: Our model predictions were validated by producing spatially varying accuracy metrics. We identified the shelf off the Bonney Coast, Great Australian Bight, and southern Western Australia as well as the slope off the Western Australian coast as suitable habitat for migration, with predicted foraging/reproduction suitable habitat in Southeast Asia region occurring on slope and in deep ocean waters. Suitable foraging habitat occurred primarily on slope and shelf break throughout most of Australia, with use of the continental shelf also occurring, predominanly in South West and Southern Australia. Depth of the water column (bathymetry) was consistently a top predictor of suitable habitat for most regions, however, dynamic environmental variables (sea surface temperature, surface height anomaly) influenced the probability of whale occurrence. Conclusions: Our results indicate suitable habitat is related to dynamic, localised oceanic processes that may occur at fine temporal scales or seasonally. An increase in the sample size of tagged whales is required to move towards developing more dynamic distribution models at seasonal and monthly temporal scales. Our validation metrics also indicated areas where further data collection is needed to improve model accuracy. This is of particular importance for pygmy blue whale management, since threats (e.g., shipping, underwater noise and artificial structures) from the offshore energy and shipping industries will persist or may increase with the onset of an offshore renewable energy sector in Australia. [ABSTRACT FROM AUTHOR]

Conservation planning traditionally relies upon static reserves; however, there is increasing emphasis on dynamic management (DM) strategies that are flexible in space and time. Due to its novelty, DM lacks best practices to guide design and implementation. We assessed the effect of planning unit size in a DM tool designed to reduce entanglement of protected whales in vertical ropes of surface buoys attached to crab traps in the lucrative U.S. Dungeness crab (Metacarcinus magister) fishery. We conducted a retrospective analysis from 2009 to 2019 with modeled distributions of blue (Balaenoptera musculus) and humpback (Megaptera novaeangliae) whales and observed fisheries effort and revenue to evaluate the effect of 7 planning unit sizes on DM tool performance. We measured performance as avoided whale entanglement risk and protected fisheries revenue. Small planning units avoided up to $47 million of revenue loss and reduced entanglement risk by up to 25% compared to the large planning units currently in use by avoiding the incidental closure of areas with low biodiversity value and high fisheries revenue. However, large planning units were less affected by an unprecedented marine heat wave in 2014–2016 and by delays in information on the distributions of whales and the fishery. Our findings suggest that the choice of planning unit size will require decision‐makers to navigate multiple socioecological considerations—rather than a one‐size‐fits‐all approach—to separate wildlife from threats under a changing climate. [ABSTRACT FROM AUTHOR]

TGF-β supergene family has a wide range of physiological functions including cell adhesion, motility, proliferation, apoptosis, and differentiation. We systematically analyzed and characterized the TGF-β gene superfamily from the whole blue whale (Balaenoptera musculus) genome, using comparative genomic and evolutionary analysis. We identified 30 TGF-β genes and were split into two subgroups, BMP-like and TGF-like. All TGF-β proteins demonstrating a basic nature, with the exception of BMP1, BMP2, BMP10, GDF2, MSTN, and NODAL modulator, had acidic characteristics. All the blue whale (B. musculus) TGF-β proteins, excluding BMP1, are thermostable based on aliphatic index. The instability index showed all proteins except the NODAL modulator was unstable. TGF-β proteins showed a hydrophilic character, with the exception of GDF1 and INHBC. Moreover, all the detected TGF-β genes showed evolutionary conserved nature. A segmental duplication was indicated by TGF-β gene family, and the Ka/Ks ratio showed that the duplicated gene pairs were subjected to selection pressure, indicating both purifying and positive selection pressure. Two possible recombination breakpoints were also predicted. This study provides insights into the genetic characterization and evolutionary aspects of the TGF-β superfamily in blue whales (B. musculus). [ABSTRACT FROM AUTHOR]

In the past decade, two large marine heatwaves (MHWs) formed in the northeast Pacific near Ocean Station Papa (OSP), one of the oldest oceanic time series stations. Physical, biogeochemical, and biological parameters observed at OSP from 2013 to 2020 are used to assess ocean response and potential impacts on marine life from the 2019 northeast Pacific MHW. The 2019 MHW reached peak surface and subsurface temperature anomalies in the summertime and had both coastal, impacting fisheries, and offshore consequences that could potentially affect multiple trophic levels in the Gulf of Alaska. In the Gulf of Alaska, the 2019 MHW was preceded by calm and stratified upper ocean conditions, which preconditioned the enhanced surface warming in late spring and early summer. The MHW coincided with lower dissolved inorganic carbon and higher pH of surface waters relative to the 2013–2020 period. A spike in the summertime chlorophyll followed by a decrease in surface macronutrients suggests increased productivity in the well‐lit stratified upper ocean during summer 2019. More blue whale calls were recorded at OSP in 2019 compared to the prior year. This study shows how the utility of long‐term, continuous oceanographic data sets and analysis with an interdisciplinary lens is necessary to understand the potential impact of MHWs on marine ecosystems. Plain Language Summary: Marine heatwaves (MHWs) are warmer than normal surface ocean temperature events. In 2019, a MHW occurred in the northeastern Pacific, and we utilized Ocean Station Papa (OSP), a multidisciplinary observing system in the Gulf of Alaska, to present the physical, biogeochemical, and biological impacts. Prior to reaching the MHW's warmest surface temperatures, the upper ocean exhibited a calm and stratified state, which facilitated the occurrence of exceptionally high sea surface temperatures. During the MHW, warm water was present well below the surface and extended throughout the water column. Prior to the MHW's warmest surface temperatures, we also observed indications of increased primary productivity through observed spikes in chlorophyll levels and reductions in nutrient concentrations. Due to data limitations, the connection between this heightened primary productivity and higher trophic levels remains unclear. Our study demonstrates the necessity of adopting holistic perspectives when seeking to understand the complexities of MHWs. Key Points: The 2019 northeastern Pacific marine heatwave had various offshore physical, biogeochemical, and biological impactsTemperature anomalies associated with the 2019 marine heatwave were observed well below the mixed layer, indicating a subsurface structure throughout the water columnLong‐term multidisciplinary observing systems are necessary to provide a holistic view of extreme events [ABSTRACT FROM AUTHOR]

Seven passive acoustic surveys for marine mammal sounds were conducted by deploying sonobuoys along ship tracks during Antarctic voyages spanning years 2006-2021. These surveys included nearly 330° of longitude throughout Antarctic (south of 60°S) and sub-Antarctic (between 50-60°S) latitudes. Here, we summarise the presence of calls from critically endangered Antarctic blue whales (Balaenoptera musculus intermedia) detected on all seven of these surveys. We describe and compare the spatial distribution of detections of three different types of Antarctic blue whale calls: unit-A, Z-calls, and D-calls. Three sets of voyages partially overlapped spatially but in different years, providing three regions (Indian Sector, Dumont d'Urville Sea, Ross Sea) to investigate differences over time for these three different call types. The proportion of sonobuoys with calls present was significantly higher in the more recent years for seven of the 15 combinations of years, regions, and call type. The proportion of sonobuoys with calls present was significantly lower only for one of the 15 combinations (unit A in the Ross Sea between 2015 vs 2017), and not significantly different for the remaining seven pairwise comparisons. We discuss possible explanations for these observations including: differences in probability of detection, whale behaviour, whale distribution, and abundance. These explanations are not mutually exclusive and cannot yet be resolved without application of complex analytical methods and collection of additional data. Lastly, we discuss future work that could help clarify the contributions of each of these potential drivers of acoustic detection. We propose continued acoustic data collection, application of new analytical methods, and collection of other synergistic data from Antarctic blue whales on their feeding grounds as a basis for future work on this species. This could provide a cost effective and holistic means of monitoring their status after the effects of 20th century industrial whaling, as well as their responses to natural and anthropogenic changes to their main prey, Antarctic krill, and a changing climate. [ABSTRACT FROM AUTHOR]

Southern hemisphere blue (Balaenoptera musculus intermedia) and fin (Balaenoptera physalus) whales are the largest predators in the Southern Ocean, with similarities in morphology and distribution. Yet, understanding of their life history and foraging is limited due to current low abundances and limited ecological data. To address these gaps, historic Antarctic blue (n = 5) and fin (n = 5) whale baleen plates, collected in 1947–1948 and recently rediscovered in the Smithsonian National Museum of Natural History, were analyzed for bulk (δ13C and δ15N) stable isotopes. Regular oscillations in isotopic ratios, interpreted as annual cycles, revealed that baleen plates contain approximately 6 years (14.35 ± 1.20 cm year−1) of life history data in blue whales and 4 years (16.52 ± 1.86 cm year−1) in fin whales. Isotopic results suggest that: (1) while in the Southern Ocean, blue and fin whales likely fed at the same trophic level but demonstrated niche differentiation; (2) fin whales appear to have had more regular annual migrations; and (3) fin whales may have migrated to ecologically distinct sub‐Antarctic waters annually while some blue whales may have resided year‐round in the Southern Ocean. These results reveal differences in ecological niche and life history strategies between Antarctic blue and fin whales during a time period when their populations were more abundant than today, and before major human‐driven climatic changes occurred in the Southern Ocean. [ABSTRACT FROM AUTHOR]

The south-east Indian Ocean population of pygmy blue whales (Balaenoptera musculus brevicauda) forages in habitats between temperate foraging grounds off southern Australia and breeding grounds in Indonesian waters. With the opportunity to forage during migration, limited seasonal variation in body condition would be expected. However, increasing numbers of individuals in poor body condition with prominent spinal columns and other features of emaciation have been sighted during their southern migration. This study aimed to measure the morphology and body condition (relative body volume to body length) of pygmy blue whales during their northbound and southbound migration. Unmanned aerial vehicles were used to obtain images of 42 pygmy blue whales (one calf, five juveniles and 36 adults, including one lactating female) in 2021 and 2022. The body lengths ranged from 15.32 to 24.32 m, and the mean relative head length, length to blowhole, width of eyes, fluke width and length of peduncle were 21.8, 18.1, 12.8, 22.9 and 21.3% respectively. There was a significant decrease in body condition of 15.3% between north and southern migrating adult whales. Given the importance of body condition for reproductive success, understanding if this loss is due to natural seasonal variation, or habitat or prey disturbance from environmental environmental or anthropogenic sources, has implications for the future management of the species. Body condition is important for successful migration, reproductive success and survival. Knowledge surrounding nutritional health of south-east Indian Ocean (SEIO) pygmy blue whales is currently lacking. We aimed to quantify and compare the body condition of SEIO pygmy blue whales at two points during northbound and southbound migration between south-west Australia and Indonesian waters. Results indicate the poorer condition of southbound migrating individuals and highlight the need to learn more about the nutritional health of this endangered species. Photograph by Grace Russell. [ABSTRACT FROM AUTHOR]

Long-term fixed passive acoustic monitoring of cetacean populations is a logistical and technological challenge, often limited by the battery capacity of the autonomous recorders. Depending on the research scope and target species, temporal subsampling of the data may become necessary to extend the deployment period. This study explores the effects of different duty cycles on metrics that describe patterns of seasonal presence, call type richness, and daily call rate of three blue whale acoustics populations in the Southern Indian Ocean. Detections of blue whale calls from continuous acoustic data were subsampled with three different duty cycles of 50%, 33%, and 25% within listening periods ranging from 1 min to 6 h. Results show that reducing the percentage of recording time reduces the accuracy of the observed seasonal patterns as well as the estimation of daily call rate and call type richness. For a specific duty cycle, short listening periods (5–30 min) are preferred to longer listening periods (1–6 h). The effects of subsampling are greater the lower the species' vocal activity or the shorter their periods of presence. These results emphasize the importance of selecting a subsampling scheme adapted to the target species. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive assessment of persistent organic pollutants (POPs) in the blubber of a stranded blue whale found on the coast of Taiwan. The analysis included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), Hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). The whale exhibited evident signs of emaciation, including low body weight, reduced blubber fat content, and thin blubber thickness. The dominant fatty acid type detected in the blubber was short-chain monounsaturated fatty acids (SC-MUFA), known to aid in thermoregulation. Stable isotope ratios indicated that the blue whale occupied a lower trophic position compared to a fin whale, suggesting its proximity to krill habitats in the Southern Ocean for feeding. The average concentrations of DDTs (1089.2 ± 4.7 ng/g lw; ΣDDT) and PCBs (1057.1 ± 49.8 ng/g lw) in the blubber were almost one order of magnitude higher than PAHs (41.7 ± 10.0 ng/g lw), HCB (70.6 ± 2. ng/g lw), and PBDEs (7.2 ± 1.2 ng/g lw). Pollutant concentrations in this individual blue whale were comparable to levels found in Norway, higher than those found in Chile, and notably lower than those found in Canada and Mexico. Calculating the biomagnification factor (BMF) for the POPs from krill (Euphausia superba) to the blue whale revealed significant bioaccumulation of pollutants in this particular whale. Additional research is imperative to achieve a thorough comprehension of bioaccumulation of POPs and their potential toxicological impacts on whale health. [ABSTRACT FROM AUTHOR]

Knowledge of genetic diversity and structure is essential for developing conservation strategies for endangered species. Blue whales were hunted to near extinction in the mid-twentieth century. Not-withstanding almost 380,000 animals killed globally, much remains unknown about their population structure and migration patterns. Herein, we use whole genome sequencing to elucidate the poorly understood population genetics of North Atlantic (NA) blue whales. We generated a de novo genome assembly for a NA blue whale to analyze 19 other whole genomic sequences and 31 complete mitochondrial genomes. Present-day and historical samples (earliest from 1876) from the Atlantic and Antarctic Oceans were included to understand the impact of whaling on the genetic diversity of this species. We found low but statistically significant population structuring and high genetic diversity. Demographic modeling using fastsimcoal2 rejected an absence of gene flow between eastern and western NA blue whales and suggested an asymmetric west to east gene flow. Introgression estimated using D-statistics between blue and fin whales (Balaenoptera physalus), was observed in all present-day samples. This gene flow was found to be unidirectional from fin whales to blue whales and accounts for ~ 3.5% of the NA blue whale's genome. Our sequencing and population structure analyses provide a genomic baseline to inform ongoing conservation strategies for this iconic species. [ABSTRACT FROM AUTHOR]

During the late nineteenth and early twentieth century, public displays of both humans and animals helped to reinforce a sense of natural order and progress in the rapidly developing United States. By placing the perceived primitive and natural world on display, a contrast could be made to the quickly modernizing nation. This article addresses two public exhibitions of whales held in the American Midwest – the 1880 Pioneer Inland Whaling Association's traveling whale show helmed by Newton and the Smithsonian Institution's full cast of a blue whale displayed at the 1904 Louisiana Purchase Exposition. Both exhibitions provided the opportunity for audiences living far from the ocean to encounter whales' bodies, a feat that merged showmanship, spectacle, and science. As deceased whales were transformed for display, they took on new meanings in their afterlives. Occurring at a moment of growth in entertainment, industry, and science, the Pioneer Inland Whaling Association's whale show emphasized tourist spectacle and novelty, while the Smithsonian Institution's exhibition reinforced prevailing ideas about natural history and American exceptionalism. Though faced with limitations, these exhibitions touted the scale and spectacle of their subject, indicating how whales emerged as a distinct category of display. [ABSTRACT FROM AUTHOR]

The blue whale, Balaenoptera musculus , is the largest animal known to have ever existed, making it an important case study in longevity and resistance to cancer. To further this and other blue whale-related research, we report a reference-quality, long-read-based genome assembly of this fascinating species. We assembled the genome from PacBio long reads and utilized Illumina/10×, optical maps, and Hi-C data for scaffolding, polishing, and manual curation. We also provided long read RNA-seq data to facilitate the annotation of the assembly by NCBI and Ensembl. Additionally, we annotated both haplotypes using TOGA and measured the genome size by flow cytometry. We then compared the blue whale genome with other cetaceans and artiodactyls, including vaquita (Phocoena sinus), the world's smallest cetacean, to investigate blue whale's unique biological traits. We found a dramatic amplification of several genes in the blue whale genome resulting from a recent burst in segmental duplications, though the possible connection between this amplification and giant body size requires further study. We also discovered sites in the insulin-like growth factor-1 gene correlated with body size in cetaceans. Finally, using our assembly to examine the heterozygosity and historical demography of Pacific and Atlantic blue whale populations, we found that the genomes of both populations are highly heterozygous and that their genetic isolation dates to the last interglacial period. Taken together, these results indicate how a high-quality, annotated blue whale genome will serve as an important resource for biology, evolution, and conservation research. [ABSTRACT FROM AUTHOR]

The reappearance of the blue whale in southern Chile in 2003has meant a number challenges for national conservation policies. It is alsocreated an opportunity to re-think the history of the southern seas and thatof the Aysen coastline in particular. The social landscape of this coastlineis characterized by poverty and passage between two well known regionChiloe and Austral Patagonia. This is an extreme environment in whichinhabitants have developed a number of adaptive strategies linked to forestand marine systems. These strategies are well documented in the historical,archaeological and ethnographic records which we will gather in order toreconstruct the environmental history of the region. Archaeo-historical recordsevidenced canoes were vital for the first inhabitants of this area. Theirrelationship with nature was based on the extensive used of resources whichin turn facilitated their integration to the local landscape characterized bythe abundance of archipelagos. This relationship was modified after a numberof historical processes unchained after the inclusion of this area to thenational economy plans. These processes promoted continuous waves ofsettlement into the region, mainly to the coastline of Aysen, modifying thetraditional adaptive strategies and promoting an intensive and abusive usedof this intrinsically labile and non-renewable landscape. The opportunity tocompile the environmental history of this area and contribute to its protectionalong with the blue whale is the challenge we present here.