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Marine mammals such as whales are an integral part of the oceanic ecosystems, however, they are also heavily affected by anthropogenic impact. In order to assess the long-term human impacts on modern whales, it is necessary to establish reliable baselines of their past and present populations. In this study we analyzed both modern and subfossil teeth from sperm whales (Physeter macrocephalus) and harbor porpoises (Phocoena phocoena). Growth layers of the teeth were investigated by the use of SEM-BSE, to gain insight into the growth dynamics and age of our specimens. Since the tooth enamel is an important indicator of diet, migration and habitat, we used Sr/Ca ratios to reconstruct the ecological niches of our taxa. Raman spectroscopy was implemented to investigate teeth surface structure and crystallographic structure, and EDX allowed us to study the chemical composition of the teeth. In conclusion, this study provides valuable insight into the ecology of modern and subfossil whales and an assessment of chemical and structural proxies that can be utilized.

Rapid changes of marine ecosystems resulting from human activities and climate change, and the subsequent reported rise of infectious diseases in marine mammals, highlight the urgency for timely detection of unusual health events negatively affecting populations. Studies reporting pathological findings in the commonly stranded harbor porpoise (Phocoena phocoena) on North Atlantic coastlines are essential to describe new and emerging causes of mortality. However, such studies often cannot be used as long-term health surveillance tools due to analytical limitations. We tested 31 variables gained from stranding-, necropsy-, dietary- and marine debris data from 405 harbor porpoises using applied supervised and unsupervised machine learning techniques to explore and analyze this large dataset. We classified and cross-correlated the variables and characterized the importance of the different variables for accurately predicting cause-of-death categories, to allow trend assessment for good conservation decision. The variable ‘age class’ seemed most influential in determining cause-of-death categories, and it became apparent that juveniles died more often due to acute causes, including bycatch, grey-seal-predation and other trauma, while adults of infectious diseases. Neonates were found in summer, and mostly without prey in their stomach and more often stranded alive. The variables assigned as part of the external examination of carcasses, such as imprints from nets and lesions induced by predators, as well as nutritional condition were most important for predicting cause-of-death categories, with a model prediction accuracy of 75%. Future porpoise monitoring, and in particular the assessment of temporal trends, should predominantly focus on influential variables as determined in this study. Pathogen- and contaminant assessment data was not available for all cases, but would be an important step to further complete the dataset. This could be vital for drawing population-inf

During evolution, animals have returned from land to water, adapting with morphological modifications to life in an aquatic environment. We compared the osteochondral units of the humeral head of marine and terrestrial mammals across species spanning a wide range of body weights, focusing on microstructural organization and biomechanical performance. Aquatic mammals feature cartilage with essentially random collagen fiber configuration, lacking the depth-dependent, arcade-like organization characteristic of terrestrial mammalian species. They have a less stiff articular cartilage at equilibrium with a significantly lower peak modulus, and at the osteochondral interface do not have a calcified cartilage layer, displaying only a thin, highly porous subchondral bone plate. This totally different constitution of the osteochondral unit in aquatic mammals reflects that accommodation of loading is the primordial function of the osteochondral unit. Recognizing the crucial importance of the microarchitecture-function relationship is pivotal for understanding articular biology and, hence, for the development of durable functional regenerative approaches for treatment of joint damage, which are thus far lacking.

In this article, the last two sentences in the Results section under "Contemporary geneflow" were incorrectly given as: Interestingly, although the estimated migration rate remained similar when excluding eastern Scottish samples (m = 3265), the direction of geneflow reversed to a unidirectional influx from western Scotland and Ireland to the North Sea. All other migration rates did not exceed 0.06 migrants per generation and were therefore considered low. But should have been: Interestingly, although the estimated migration rate remained similar when excluding eastern Scottish samples (m = 0.3265), the direction of geneflow reversed to a unidirectional influx from western Scotland and Ireland to the North Sea. All other migration rates did not exceed 0.06 migrants per generation and were therefore considered low. The given value for the estimated migration rate between the two mentioned groups was wrong. In the text it says m = 3265 when it should be m = 0.3265 instead. The original article has been corrected.

In August 2021, a large-scale mortality event affected harbor porpoises (Phocoena phocoena) in the Netherlands. Pathology and ancillary testing of 22 animals indicated that the most likely cause of death was Erysipelothrix rhusiopathiae infection. This zoonotic agent poses a health hazard for cetaceans and possibly for persons handling cetacean carcasses.

During evolution, animals have returned from land to water, adapting with morpho-logical modifications to life in an aquatic environment. We compared the osteochondral units of the humeral head of marine and terrestrial mammals across species spanning a wide range of body weights, focusing on microstructural organization and biomechanical performance. Aquatic mammals feature cartilage with essentially random collagen fiber configuration, lacking the depth-dependent, arcade-like organization characteristic of terrestrial mammalian species. They have a less stiff articular cartilage at equilibrium with a significantly lower peak modulus, and at the osteochondral interface do not have a calcified cartilage layer, displaying only a thin, highly porous subchondral bone plate. This totally different constitution of the osteochondral unit in aquatic mammals reflects that accommodation of loading is the primordial function of the osteochondral unit. Recognizing the crucial importance of the microarchitecture-function relationship is pivotal for understanding articular biology and, hence, for the development of durable functional regenerative approaches for treatment of joint damage, which are thus far lacking.

Post-mortem research on porpoises (Phocoena phocoena) from Dutch waters, 2022. Biological data, health status and causes of death. This annual report presents the results of post-mortem examinations of beached harbour porpoises in 2022. One of the main objectives of the research is to quantify human-induced causes of death. In 2022, 57 dead harbour porpoises were examined: 31 males and 26 females, comprising 18 adults, 27 juveniles and 12 neonates. In addition two male foetuses were examined. Most of the examined harbour porpoises died as a result of infectious diseases (40.4%) and grey seal attacks (24.6%). Bycatch was the most likely cause of death for six porpoises (10.5%) and seven other porpoises died following trauma of unclear origin (12.3%)., In dit jaarrapport worden de resultaten gepresenteerd van pathologisch onderzoek aan gestrande bruinvissen in 2022. Eén van de hoofddoelen van het onderzoek is het kwantificeren van sterfte van bruinvissen door menselijk toedoen. In 2022 zijn 57 dode bruinvissen onderzocht: 31 mannelijke en 26 vrouwelijke, waarvan 18 volwassen, 27 juveniel en 12 neonaat. Er werden daarnaast twee mannelijke foetussen aangetroffen, onderzocht en bemonsterd. De meeste van de onderzochte bruinvissen stierven door infectieziekten (40,4%) en grijzezeehondaanvallen (24,6%). Bijvangst was de meest waarschijnlijke doodsoorzaak van zes bruinvissen (10,5%). Zeven andere bruinvissen stierven als gevolg van trauma door onduidelijke oorsprong (12,3%).

A key driver in determining the distribution and demography of cetaceans is the dispersion of their prey, in terms of availability, abundance and quality. A Working Group on Resource Depletion has been established within ASCOBANS to review current knowledge and develop recommendations for research and action. It includes members with expertise in veterinary and fishery science, cetacean biology, ecology and conservation. The group has eight terms of reference - reviewing and collating recent information on resource depletion and its impacts, prey distribution and abundance, health and condition indicators, small cetacean diet, spatio-temporal trends in small cetacean species, emerging technologies, integrating information from multiple data sources, and making recommendations for possible mitigation measures to aid conservation. As a first step, the group has summarised information on the diets of all small cetacean species regularly occurring in the ASCOBANS Agreement Area, and explored the parameters required to assess cetacean health and condition at both an individual and population level. The need to better understand prey choice in terms of prey availability and caloric content is highlighted along with the development of indicators of food shortage through necropsies of dead animals and photographic assessments of body condition in live animals. Future research, monitoring and conservation needs include refining the definition of prey depletion, developing prey depletion reference points, and articulating associated conservation objectives. We also need a better understanding of the relationships between cetacean physiology, energetics, body condition, health and diet, and of the population and ecosystem level consequences of prey depletion (e.g. based on the use of ecosystem models). Improved monitoring of prey and cetacean distribution and abundance at relevant spatiotemporal scales would facilitate estimation and mapping of resource depletion risk

In August 2021, a large-scale mortality event affected harbor porpoises (Phocoena phocoena) in the Netherlands. Pathology and ancillary testing of 22 animals indicated that the most likely cause of death was Erysipelothrix rhusiopathiae infection. This zoonotic agent poses a health hazard for cetaceans and possibly for persons handling cetacean carcasses.

In August 2021, a large-scale mortality event affected harbor porpoises (Phocoena phocoena) in the Netherlands. Pathology and ancillary testing of 22 animals indicated that the most likely cause of death was Erysipelothrix rhusiopathiae infection. This zoonotic agent poses a health hazard for cetaceans and possibly for persons handling cetacean carcasses.

Rapid changes of marine ecosystems resulting from human activities and climate change, and the subsequent reported rise of infectious diseases in marine mammals, highlight the urgency for timely detection of unusual health events negatively affecting populations. Studies reporting pathological findings in the commonly stranded harbor porpoise (Phocoena phocoena) on North Atlantic coastlines are essential to describe new and emerging causes of mortality. However, such studies often cannot be used as long-term health surveillance tools due to analytical limitations. We tested 31 variables gained from stranding-, necropsy-, dietary- and marine debris data from 405 harbor porpoises using applied supervised and unsupervised machine learning techniques to explore and analyze this large dataset. We classified and cross-correlated the variables and characterized the importance of the different variables for accurately predicting cause-of-death categories, to allow trend assessment for good conservation decision. The variable ‘age class’ seemed most influential in determining cause-of-death categories, and it became apparent that juveniles died more often due to acute causes, including bycatch, grey-seal-predation and other trauma, while adults of infectious diseases. Neonates were found in summer, and mostly without prey in their stomach and more often stranded alive. The variables assigned as part of the external examination of carcasses, such as imprints from nets and lesions induced by predators, as well as nutritional condition were most important for predicting cause-of-death categories, with a model prediction accuracy of 75%. Future porpoise monitoring, and in particular the assessment of temporal trends, should predominantly focus on influential variables as determined in this study. Pathogen- and contaminant assessment data was not available for all cases, but would be an important step to further complete the dataset. This could be vital for drawing population-inf

Humans impact natural systems at an unprecedented rate. The North Sea is one of the regions in the world with the highest levels of anthropogenic activity. Here, the harbor porpoise (Phocoena phocoena) is an abundant species and is often regarded as an ecosystem sentinel. A post-mortem surveillance program was established in the Netherlands aimed at increasing knowledge of the effects of human activities on harbor porpoises. In this study, we describe the pathological findings related to anthropogenic and natural causes of death categories in 612 harbor porpoises that stranded between 2008 and 2019, and assess their relations to age, sex, season, and location. The largest anthropogenic category was bycatch (17%), with mainly juveniles affected and peak periods in March and September–October. Other, infrequently diagnosed anthropogenic causes of death were trauma (4%), largely most likely due to ship collisions, and marine debris ingestion and entanglement (0.3%). The risk of dying from anthropogenic causes was highest for juveniles. Lesions compatible with noise-induced hearing loss were investigated in carcasses which were fresh enough to do so (n = 50), with lesions apparent in two porpoises. Non-direct human-induced threats included infectious diseases, which were by far the largest cause of death category (32%), and affected mainly adults. Also, gray seal (Halichoerus grypus) attacks were a frequently assigned cause of death category (24%). There were more acute predation cases in the earlier study years, while porpoises with lesions that suggested escape from gray seal attacks were diagnosed more recently, which could suggest that porpoises adapted to this threat. Our study contributes to understanding porpoise health in response to persisting, new, emerging, and cumulative threats. Building up such knowledge is crucial for conservation management of this protected species.

The apex or apical region of the cochlear spiral within the inner ear encodes for low-frequency sounds. The disposition of sensory hair cells on the organ of Corti is largely variable in the apical region of mammals, and it does not necessarily follow the typical three-row pattern of outer hair cells (OHCs). As most underwater noise sources contain low-frequency components, we expect to find most lesions in the apical region of the cochlea of toothed whales, in cases of permanent noise-induced hearing loss. To further understand how man-made noise might affect cetacean hearing, there is a need to describe normal morphological features of the apex and document interspecific anatomic variations in cetaceans. However, distinguishing between apical normal variability and hair cell death is challenging. We describe anatomical features of the organ of Corti of the apex in 23 ears from five species of toothed whales (harbor porpoise Phocoena phocoena, spinner dolphin Stenella longirostris, pantropical spotted dolphin Stenella attenuata, pygmy sperm whale Kogia breviceps, and beluga whale Delphinapterus leucas) by scanning electron microscopy and immunofluorescence. Our results showed an initial region where the lowest frequencies are encoded with two or three rows of OHCs, followed by the typical configuration of three OHC rows and three rows of supporting Deiters' cells. Whenever two rows of OHCs were detected, there were usually only two corresponding rows of supporting Deiters' cells, suggesting that the number of rows of Deiters' cells is a good indicator to distinguish between normal and pathological features.