Molecular identification of whales remains from the Keller Peninsula, Admiralty Bay, King George Island, Antarctica.

At the beginning of the 20th century, intense whaling activity took place in the South Shetland Islands, which is represented today in the form of ruins and numerous whale bones scattered along several Antarctic beaches. Despite being exposed to a harsh environment throughout the last decades, the present manuscript tried to answer if these bone remains still have viable DNA to allow species' identification using molecular methods. Several individuals were collected from the shores of Keller Peninsula, Admiralty Bay, Antarctica, and submitted to DNA extraction, amplification and Sanger sequencing. The challenging identification of these bone fragments proved to be still feasible. Mitochondrial DNA was successfully extracted, amplified and sequenced. A database with 43 sequences including previously published and newly determined sequences were built and enabled the precise identification to species level for some of the collected samples, therefore shedding light on the whales species that inhabited the region and how their overexploitation seems to have affected modern day presence of these species within the study area.

Diverse baleen whale acoustic occurrence around two sub-Antarctic islands: A tale of residents and visitors.

Knowledge on the occurrence and behaviour of baleen whales around sub-Antarctic regions is limited, and usually based on short, seasonal sighting research from shore or research vessels and whaling records, neither of which provide accurate and comprehensive year-round perspectives of these animals' ecology. We investigated the seasonal acoustic occurrence and diel vocalizing pattern of baleen whales around the sub-Antarctic Prince Edward Islands (PEIs) using passive acoustic monitoring data from mid-2021 to mid-2023, detecting six distinct baleen whale songs from Antarctic blue whales, Madagascan pygmy blue whales, fin whales, Antarctic minke whales, humpback whales, and sei whales. Antarctic blue and fin whales were detected year-round whereas the other species' songs were detected seasonally, including a new Antarctic minke whale bio-duck song sub-type described here for the first time. Antarctic minke and sei whales were more vocally active at night-time whereas the other species had no clear diel vocalizing patterns. Random forest models identified month and/or sea surface temperature as the most important predictors of all baleen whale acoustic occurrence. These novel results highlight the PEIs as a useful habitat for baleen whales given the number of species that inhabit or transit through this region.

Whale recovery and the emerging human-wildlife conflict over Antarctic krill.

The Southern Ocean ecosystem has undergone extensive changes in the past two centuries driven by industrial sealing and whaling, climate change and commercial fishing. However, following the end of commercial whaling, some populations of whales in this region are recovering. Baleen whales are reliant on Antarctic krill, which is also the largest Southern Ocean fishery. Since 1993, krill catch has increased fourfold, buoyed by nutritional supplement and aquaculture industries. In this Perspective, we approximate baleen whale consumption of Antarctic krill before and after whaling to examine if the ecosystem can support both humans and whales as krill predators. Our back-of-the-envelope calculations suggest that current krill biomass cannot support both an expanding krill fishery and the recovery of whale populations to pre-whaling sizes, highlighting an emerging human-wildlife conflict. We then provide recommendations for enhancing sustainability in this region by reducing encounters with whales and bolstering the krill population.

Effectiveness of marine protected areas in safeguarding important migratory megafauna habitat.

Marine protected areas (MPAs) are a commonly used management tool to safeguard marine life from anthropogenic impacts, yet their efficacy often remains untested. Evaluating how highly dynamic marine species use static MPAs is challenging but becoming more feasible with the advancement of telemetry data. Here, we focus on southern right whales (Eubalaena australis, SRWs) in the waters off Aotearoa/New Zealand, which declined from 30,000 whales to fewer than 40 mature females due to whaling. Now numbering in the low thousands, the key socializing and nursery areas for this population in the remote subantarctic islands are under the protection of different types of MPAs. However, the effectiveness of these MPAs in encompassing important whale habitat and protecting the whales from vessel traffic has not been investigated. To address this, we analyzed telemetry data from 29 SRWs tagged at the Auckland Islands between 2009 and 2022. We identified two previously unknown and currently unprotected areas that were used by the whales for important behaviors such as foraging, socializing, or resting. Additionally, by combining whale locations and vessel tracking data (2020-2022) during peak breeding period (June to October), we found high spatiotemporal overlap between whales and vessels within several MPAs, suggesting the whales could still be vulnerable to multiple anthropogenic stressors even when within areas designated for protection. Our results identify areas to be prioritized for future monitoring and investigation to support the ongoing recovery of this SRW population, as well as highlight the overarching importance of assessing MPA effectiveness post-implementation, especially in a changing climate.

Into the Blue: Exploring genetic mechanisms behind the evolution of baleen whales.

Marine ecosystems are ideal for studying evolutionary adaptations involved in lineage diversification due to few physical barriers and reduced opportunities for strict allopatry compared to terrestrial ecosystems. Cetaceans (whales, dolphins, and porpoises) are a diverse group of mammals that successfully adapted to various habitats within the aquatic environment around 50 million years ago. While the overall adaptive transition from terrestrial to fully aquatic species is relatively well understood, the radiation of modern whales is still unclear. Here high-quality genomes derived from previously published data were used to identify genomic regions that potentially underpinned the diversification of baleen whales (Balaenopteridae). A robust molecular phylogeny was reconstructed based on 10,159 single copy and complete genes for eight mysticetes, seven odontocetes and two cetacean outgroups. Analysis of positive selection across 3,150 genes revealed that balaenopterids have undergone numerous idiosyncratic and convergent genomic variations that may explain their diversification. Genes associated with aging, survival and homeostasis were enriched in all species. Additionally, positive selection on genes involved in the immune system were disclosed for the two largest species, blue and fin whales. Such genes can potentially be ascribed to their morphological evolution, allowing them to attain greater length and increased cell number. Further evidence is presented about gene regions that might have contributed to the extensive anatomical changes shown by cetaceans, including adaptation to distinct environments and diets. This study contributes to our understanding of the genomic basis of diversification in baleen whales and the molecular changes linked to their adaptive radiation, thereby enhancing our understanding of cetacean evolution.

Persistent plastic: Insights from seawater weathering and simulated whale gut.

Single-use plastics make up 60-95 % of marine plastic pollution, including common commodity films used for packaging and bags. Plastic film breaks down as a function of environmental variables like wave action, wind, temperature, and UV radiation. Here, we focus on how films degrade in cold waters across depths, time, and simulated mammal digestion. Five types of single-use film plastics (HDPE thin & thick, LDPE, PP, PE) were weathered for eight months in temperate waters at surface and depth in the Salish Sea, WA, USA, and subsequently exposed to a laboratory-simulated gray whale stomach. None of the types of plastics examined here fully degraded during the course of this 8 months study. Weathering time and depth significantly impacted many of the physical attributes of plastics, while exposure to a simulated whale gut did not. If unable to degrade plastics through digestion, whales risk long-term exposure to physical and chemical attributes of plastics.

Relationship between skin and body condition in three species of baleen whales.

The assessment of free-ranging cetacean health through the study of skin conditions using photographs has gained prominence in recent years. However, little attention has been given to the relationships between cetacean skin conditions, species, and body condition. To explore this relationship among baleen whale species along the northwestern coast of Spain, we employed a non-invasive method involving photograph analysis. In this study, we examined skin conditions (including injuries, epizoites and ectoparasites, pigmentation disorders, skin lesions, and anatomical malformations) and body condition (overall physical contours and form, as an indicator of nutritional status and health) in 3 species of whales (blue, fin, and minke whales). This methodology facilitated the identification of 29 subcategories of distinct skin conditions and an assessment of body condition over a 5 yr period (2017 to 2021). In our study, we present evidence linking hypopigmentation, protruding pieces of tissue, and tattoo-like lesions to 'Poor' body condition in the 3 baleen whale species. Fin whales exhibited a higher susceptibility to mottling (prevalence = 17.7%), while blue whales were more prone to starbursts (prevalence = 90.5%). Additionally, we found a significant relationship between skin condition diversity and individual body condition. Our findings contribute valuable information to the broader understanding of the health status of baleen whales. Further investigations are necessary to delve into the etiology of the documented skin conditions and their potential implications for individual survival. This study serves as a foundation for ongoing research aimed at advancing our comprehension of these findings.

Anisakid parasite diversity in a pygmy sperm whale, Kogia breviceps (Cetacea: Kogiidae) stranded at the edge of its distribution range in the Northeast Atlantic Ocean.

Anisakid nematodes are a globally distributed group of marine mammal parasites. Kogiid whales, including the pygmy sperm whale Kogia breviceps, host an assemblage of specific anisakid species. Currently, three species are known to be specific to kogiid hosts, i.e., Skrjabinisakis paggiae, S. brevispiculata, and the less studied Pseudoterranova ceticola. The aim of this study was to investigate the species diversity of anisakid nematodes sampled from a pygmy sperm whale stranded in 2013 at the edge of its distribution range in the Northeast Atlantic, specifically in the North of Scotland. Nematodes were assigned to genus level based on morphology and identified by sequence analysis of the mtDNA cox2 gene and the rDNA ITS region. The present finding represents the first observation of syntopic occurrence of adult stages of S. brevispiculata, S. paggiae, and P. ceticola in a pygmy sperm whale in the Northeast Atlantic, and represent the northernmost record of these species in this area. Skrjabinisakis brevispiculata was the most abundant species, accounting for 55% of the identified nematodes, predominantly in the adult stage. Anisakis simplex (s.s.) was also abundant, with most specimens in the preadult stage, followed by S. paggiae and P. ceticola. The pygmy sperm whale is rarely documented in Scottish waters, and its occurrence in the area could suggest expansion of its geographic range. The presence of S. brevispiculata, S. paggiae, and P. ceticola in this whale species in this region may indicate a shift in the whole host community involved in the life cycle of these parasites in northern waters. However, it is also plausible that these parasites were acquired while the whale was feeding in more southern regions, before migrating northbound.

Title: Diversité des parasites Anisakidae chez un cachalot pygmée, Kogia breviceps (Cetacea : Kogiidae) échoué à la limite de son aire de répartition dans l'Atlantique Nord-Est. Abstract: Les nématodes Anisakidae sont un groupe de parasites de mammifères marins réparti dans le monde entier. Les cétacés Kogiidae, y compris le cachalot pygmée Kogia breviceps, hébergent un assemblage d'espèces d'Anisakidae spécifiques. Actuellement, trois espèces sont connues pour être spécifiques aux hôtes Kogiidae, à savoir Skrjabinisakis paggiae, S. brevispiculata et Pseudoterranova ceticola, la moins étudiée. Le but de cette étude était d'étudier la diversité des espèces de nématodes Anisakidae échantillonnés sur un cachalot pygmée échoué en 2013 à la limite de son aire de répartition dans l'Atlantique Nord-Est, plus précisément au nord de l'Écosse. Les nématodes ont été attribués au niveau du genre en fonction de la morphologie et identifiés par analyse de séquence du gène cox2 de l'ADNmt et de la région ITS de l'ADNr. La présente découverte représente la première observation de l'apparition syntopique de stades adultes de S. brevispiculata, S. paggiae et P. ceticola chez un cachalot pygmée dans l'océan Atlantique Nord-Est, et représente le signalement le plus septentrional de ces espèces dans cette zone. Skrjabinisakis brevispiculata était l'espèce la plus abondante, représentant 55% des nématodes identifiés, principalement au stade adulte. Anisakis simplex (s.s.) était également abondant, la plupart des spécimens étant au stade préadulte, suivi par S. paggiae et P. ceticola. Le cachalot pygmée est rarement documenté dans les eaux écossaises et sa présence dans la région pourrait suggérer une expansion de son aire de répartition géographique. La présence de S. brevispiculata, S. paggiae et P. ceticola chez cette espèce de cachalot dans cette région peut indiquer un changement dans l'ensemble de la communauté hôte impliquée dans le cycle de vie de ces parasites dans les eaux nordiques. Cependant, il est également plausible que ces parasites aient été acquis alors que le cachalot se nourrissait dans des régions plus au sud, avant de migrer vers le nord.

Finds of Skulls of Juvenile Kurdalagonus maicopicus (Cetacea, Cetotheriidae) in the Upper Miocene of the Republic of Adygea.

Fragments of two skulls of young cetotheriid baleen whales were described from the Fortep'yanka 2 locality (Russia, Republic of Adygea, Maikop district, Fortep'yanka River valley, Upper Miocene, Upper Sarmatian, Blinovskaya Formation). The finds were attributed to Kurdalagonus maicopicus (Spasskii, 1951) based on the morphology of the posterior (mastoid) process of the petrosal bone, the structure of the posterior edge of the temporal fossa, and the S-like shape of the supraoccipital ridges. The skull proportions and the degree of suture closure made it possible to determine the individual age of the whales within a year. New finds significantly complement the data on the structure of the sutures of the lateral wall of the skull and age-related variability of cranial morphology in representatives of the genus Kurdalagonus.

Improved Latin hypercube sampling initialization-based whale optimization algorithm for COVID-19 X-ray multi-threshold image segmentation.

Image segmentation techniques play a vital role in aiding COVID-19 diagnosis. Multi-threshold image segmentation methods are favored for their computational simplicity and operational efficiency. Existing threshold selection techniques in multi-threshold image segmentation, such as Kapur based on exhaustive enumeration, often hamper efficiency and accuracy. The whale optimization algorithm (WOA) has shown promise in addressing this challenge, but issues persist, including poor stability, low efficiency, and accuracy in COVID-19 threshold image segmentation. To tackle these issues, we introduce a Latin hypercube sampling initialization-based multi-strategy enhanced WOA (CAGWOA). It incorporates a COS sampling initialization strategy (COSI), an adaptive global search approach (GS), and an all-dimensional neighborhood mechanism (ADN). COSI leverages probability density functions created from Latin hypercube sampling, ensuring even solution space coverage to improve the stability of the segmentation model. GS widens the exploration scope to combat stagnation during iterations and improve segmentation efficiency. ADN refines convergence accuracy around optimal individuals to improve segmentation accuracy. CAGWOA's performance is validated through experiments on various benchmark function test sets. Furthermore, we apply CAGWOA alongside similar methods in a multi-threshold image segmentation model for comparative experiments on lung X-ray images of infected patients. The results demonstrate CAGWOA's superiority, including better image detail preservation, clear segmentation boundaries, and adaptability across different threshold levels.

Machine learning with taxonomic family delimitation aids in the classification of ephemeral beaked whale events in passive acoustic monitoring.

Passive acoustic monitoring is an essential tool for studying beaked whale populations. This approach can monitor elusive and pelagic species, but the volume of data it generates has overwhelmed researchers' ability to quantify species occurrence for effective conservation and management efforts. Automation of data processing is crucial, and machine learning algorithms can rapidly identify species using their sounds. Beaked whale acoustic events, often infrequent and ephemeral, can be missed when co-occurring with signals of more abundant, and acoustically active species that dominate acoustic recordings. Prior efforts on large-scale classification of beaked whale signals with deep neural networks (DNNs) have approached the class as one of many classes, including other odontocete species and anthropogenic signals. That approach tends to miss ephemeral events in favor of more common and dominant classes. Here, we describe a DNN method for improved classification of beaked whale species using an extensive dataset from the western North Atlantic. We demonstrate that by training a DNN to focus on the taxonomic family of beaked whales, ephemeral events were correctly and efficiently identified to species, even with few echolocation clicks. By retrieving ephemeral events, this method can support improved estimation of beaked whale occurrence in regions of high odontocete acoustic activity.

Foraging dives of southern right whales (Eubalaena australis) in relation to larger zooplankton size prey availability in Golfo Nuevo, Península Valdés, Argentina.

Southern right whales (SRWs, Eubalaena australis) have been observed feeding both at and below the surface (< 10 m) in Golfo Nuevo (42°42' S, 64°30' W), Península Valdés, Argentina, an area traditionally recognized as calving ground. In addition, we documented diving feeding behavior in SRWs during their stay in this gulf, which has not been previously described. We assessed this behavior using suction-cup-attached video-imaging tags (CRITTERCAMs) on individual whales. A total of eight CRITTERCAM deployments were successful, and feeding events were documented in all SRWs successfully equipped with CRITTERCAMs. The highest speeds occurred during the ascent phase, and the average diving time was 6 min 45 s ± 3 min 41 s for SRWs. Concurrently, zooplankton samples were collected from the subsurface and bottom of the water in areas where tagged whales dived to assess differences in composition, abundance, and biomass. Copepods dominated the upper layer, while euphausiids were more abundant in the deeper sample. Furthermore, zooplankton total biomass was five times higher at depth (2515.93 mg/m3) compared to the subsurface (500.35 mg/m3). Differences in zooplankton characteristics between depths, combined with CRITTERCAM videos, indicated that SRWs exploit high concentrations of organisms near the seafloor during daytime feeding dives. This study provides baseline insights into how SRWs utilize Península Valdés during their stay in the area.

Long-distance communication can enable collective migration in a dynamic seascape.

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.

Comparison of carbon, nitrogen, and oxygen stable isotope ratios and mercury concentrations in muscle tissues of five beaked whale species and sperm whales stranded in Hokkaido, Japan.

We studied δ13C, δ15N and δ18O values, and total mercury (THg) concentrations in muscle samples from deep-sea predators - five beaked whale species and sperm whales - stranded along the coast of Hokkaido, in the north of Japan in 2010 and 2019. The δ13C, δ15N and δ18O values, THg concentrations, and body length (BL) of Stejneger's beaked whales were similar to those of Hubbs' beaked whales, which belong to the same genus. In contrast, δ13C values, THg concentrations, and BL of Sato's beaked whales were markedly different from those of Baird's beaked whales, which belong to the same genus. Stejneger's and Hubbs' beaked whales living around Hokkaido may compete in their ecological niches, whereas Sato's and Baird's beaked whales may segregate their ecological niches. Although Cuvier's beaked whales and sperm whales belong to different genera and their BLs were significantly different, their δ13C and δ15N values were similar, probably because they can dive and stay in deeper waters than other beaked whale species. The δ13C values in combined samples from all whales increased with increasing BL, probably owing to the larger whale species' dietary preference for squid. The δ13C values in combined samples from all whales were positively correlated with THg concentrations, whereas the δ15N values in the combined samples were negatively correlated. The δ18O values in combined samples from most whales tended to be positively correlated with THg concentrations. These correlations may be explained by a higher THg load from deep-sea feeding than from pelagic feeding and by a feeding shift towards lower trophic levels.

Distribution models of baleen whale species in the Irish Exclusive Economic Zone to inform management and conservation.

Irish waters are under increasing pressure from anthropogenic sources including the development of offshore renewable energy, vessel traffic and fishing activity. Spatial planning requires robust datasets on species distribution and the identification of important habitats to inform the planning process. Despite limited survey effort, long-term citizen science data on whale presence are available and provide an opportunity to fill information gaps. Using presence-only data as well as a variety of environmental variables, we constructed seasonal ensemble species distribution models based on five different algorithms for minke whales, fin whales, humpback whales, sei whales, and blue whales. The models predicted that the coastal waters off the south and west of Ireland are particularly suitable for minke, fin and humpback whales. Offshore waters in the Porcupine Seabight area were identified as a relevant habitat for fin whales, sei whales and blue whales. We combined model outputs with data on maritime traffic, fishing activity and offshore wind farms to measure the exposure of all the species to these pressures, identifying areas of concern. This study serves as a baseline for the species presence in Irish waters over the last two decades to help develop appropriate marine spatial plans in the future.

Universal wing- and fin-beat frequency scaling.

We derive an equation that applies for the wing-beat frequency of flying animals and to the fin-stroke frequency of diving animals like penguins and whales. The equation states that the wing/fin-beat frequency is proportional to the square root of the animal's mass divided by the wing area. Data for birds, insects, bats, and even a robotic bird-supplemented by data for whales and penguins that must swim to stay submerged-show that the constant of proportionality is to a good approximation the same across all species; thus the equation is universal. The wing/fin-beat frequency equation is derived by dimensional analysis, which is a standard method of reasoning in physics. We finally demonstrate that a mathematically even simpler expression without the animal mass does not apply.