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As an innovative type of damper seal, the scallop damper seal (SDS) has shown greatly improved sealing performance for the high-compactness supercritical CO2 (S-CO2) turbomachinery, but leakage-induced excitation forces have an impact on the rotor stability. In this research, we improve the rotordynamic solution based on the multi-frequency elliptic whirling model for the S-CO2 seals and investigate the leakage-induced excitation behavior of SDS depending on seal geometry and operating condition. By comparing the results of a labyrinth seal and a full-partition pocket damper seal, we prove that SDS has better rotordynamic performance for the S-CO2 compressor. The results show that increasing the pressure drop favors greater direct stiffness and effective damping of the SDS. Inlet preswirl changes the direction of fluid-response force to coincide with the rotor motion, which is detrimental to rotor stability. Changing the cavity depth has no significant effect on the dynamic characteristics of the SDS, but shortening the cavity length reduces the direct stiffness to below zero. Supplementing the number of circumferential cavities increases the direct stiffness and effective damping but results in SDS not being able to be machined directly by milling cutters. The design with 12 circumferential cavities is recommended for the 100-kW-class S-CO2 compressor. [ABSTRACT FROM AUTHOR]

The millimetre wave radar signatures of sea lions collected from three animals in the outdoor seal pool available at the Sea Mammal Research Unit in St Andrews in the Autumn of 2021 is reported. The objective is to study the radar amplitude and Doppler signatures of the animals when their full body or part thereof is above water, which is important for the application of autonomous marine navigation. The data was collected using 24 GHz (K‐band) and 77 GHz (W‐band) Frequency Modulated Continuous Wave radars with linear polarisation. It has been demonstrated that the sea lions were very clearly detected by the radars with Signal to Noise Ratio greater than 30 dB at a range of 40 m. The calculated modal radar cross section (RCS) of the sea lions in HH polarisation at 24 and 77 GHz vary from −48 to −26 dBsm and −48 to −28 dBsm respectively, corresponding to the different body parts and the amount of exposure to the radar beam. In VV polarisation, the modal RCS value range is from −49 to −26 dBsm and −49 to −22 dBsm respectively. The corresponding maximum RCS and the Cumulative Distribution Function results are also reported. [ABSTRACT FROM AUTHOR]

Generally, a species is defined as an independent unit that is reproductively isolated from others. However, deviations from this definition are not uncommon. For example, cross-fertilization in pinnipeds has been reported among at least 10 species. Herein, we describe an unexpected hybridization that occurred between female gray seals (Halichoerus grypus) and male spotted seals (Phoca largha) in the presence of adult male gray seals in a mixed-species seal population under human care. To our knowledge, these are the first cases of gray and spotted seal hybrids ever reported. The three hybridized offspring had the appearance of a gray seal body and a spotted seal head. Microsatellite DNA markers were employed as genetic evidence to further support the hybridization events. Our study suggests a natural preference for interspecies hybridization between female gray seals and male spotted seals in human care. Following that, potential causes of cross-species hybridization, including female preference, male competition, and some other factors, are discussed. [ABSTRACT FROM AUTHOR]

Disturbance due to tourism may impact the critically endangered population of harbor seals (Phoca vitulina) in Iceland. Improved seal watching management is a promising strategy for seal conservation in Iceland. Previous research indicates that value orientation of tourists can predict acceptance of wildlife management and awareness of potential impacts of tourism on seals. The goal of this study was to (a) define biospheric and egoistic value orientation of seal watching visitors, (b) investigate how these values correlate with the opinion of visitors towards different management actions and awareness of potential impact of tourism on seals, and (c) investigate which management actions would be acceptable for visitors. Visitor questionnaires were distributed in NW Iceland (n = 597). Results show that seal watching visitors in general had high biospheric values, low egoistic values, and were open to most management actions suggested in the study. High biospheric values were correlated with acceptance of management actions and awareness of the usefulness of regulations. High egoistic values were correlated with low acceptance of management actions and low awareness of the impacts of seal watching. Results will inform managers on how to optimize management strategies at seal watching sites in Iceland and elsewhere. [ABSTRACT FROM AUTHOR]

Rhythmic patterns in interactive contexts characterize human behaviours such as conversational turn-taking. These timed patterns are also present in other animals, and often described as rhythm. Understanding fine-grained temporal adjustments in interaction requires complementary quantitative methodologies. Here, we showcase how vocal interactive rhythmicity in a non-human animal can be quantified using a multi-method approach. We record vocal interactions in harbour seal pups (Phoca vitulina) under controlled conditions. We analyse these data by combining analytical approaches, namely categorical rhythm analysis, circular statistics and time series analyses. We test whether pups' vocal rhythmicity varies across behavioural contexts depending on the absence or presence of a calling partner. Four research questions illustrate which analytical approaches are complementary versus orthogonal. For our data, circular statistics and categorical rhythms suggest that a calling partner affects a pup's call timing. Granger causality suggests that pups predictively adjust their call timing when interacting with a real partner. Lastly, the ADaptation and Anticipation Model estimates statistical parameters for a potential mechanism of temporal adaptation and anticipation. Our analytical complementary approach constitutes a proof of concept; it shows feasibility in applying typically unrelated techniques to seals to quantify vocal rhythmic interactivity across behavioural contexts. This article is part of a discussion meeting issue 'Face2face: advancing the science of social interaction'. [ABSTRACT FROM AUTHOR]

The North Sea faces intense ship traffic owing to increasing human activities at sea. As harbour seals (Phoca vitulina) are abundant top predators in the North Sea, it is hypothesised that they experience repeated, high-amplitude vessel exposures. Here, we test this hypothesis by quantifying vessel noise exposures from deployments of long-term sound and movement tags (DTAGs) on nine harbour seals from the Wadden Sea. An automated tool was developed to detect intervals of elevated noise in the sound recordings. An assessment by multiple raters was performed to classify the source as either vessels or other sounds. A total of 133 vessel passes were identified with received levels > 97 dB re 1µPa RMS in the 2 kHz decidecade band and with ambient noise > 6 dB below this detection threshold. Tagged seals spent most of their time within Marine Protected Areas (89 ± 13%, mean ± SD) and were exposed to high-amplitude vessel passes 4.3 ± 1.6 times per day. Only 32% of vessel passes were plausibly associated with an AIS-registered vessel. We conclude that seals in industrialized waters are exposed repeatedly to vessel noise, even in areas designated as protected, and that exposures are poorly predicted by AIS data. [ABSTRACT FROM AUTHOR]

The Baltic Proper harbour porpoise population is listed as Critically Endangered by IUCN, and only a few hundred animals remain. One of the most serious threats to this population is bycatch in static net fisheries. To minimize bycatch, ICES has proposed that acoustic deterrent devices, pingers, should be used on static nets within the population's range.However, there have previously been indications that grey seals learn to associate the pinger sounds with the presence of nets with easily accessible prey, and that pinger use therefore can increase the risk of seal depredation in static net fisheries.In recent years, pingers operating at higher frequencies have been made commercially available, the idea being that harbour porpoises will still be able to hear the sound at 50–120 kHz while this will be above or at the limit of seal hearing. This would mean that such high‐frequency pingers would not induce this so‐called dinner‐bell effect.In this study, data were collected from active commercial static net fisheries in the Baltic Proper, using two types of high‐frequency pingers operating at 50–120 and 70 kHz, respectively. Pingers were attached to nets in accordance with manufacturers' guidelines, and fishers were asked to estimate the catch loss owing to seals in nets with and without pingers.Data were received from 646 deployments made between May 2019 and September 2020. Four generalized mixed effect models were developed with relevant variables.The results suggest using high‐frequency pingers does not increase seal depredation on static nets. It is concluded that pingers could be used as an interim measure to minimize bycatch of the Critically Endangered Baltic Proper harbour porpoise population. [ABSTRACT FROM AUTHOR]

The article explores the interpretation of a tablet found at the Pylos archaeological site in Greece. The tablet, known as Vn 130, has been the subject of debate among scholars. One interpretation suggests that it relates to the work of unguent-boilers, while another proposes that it deals with the collection or receipt of bronze vessels. The author presents evidence supporting the latter interpretation, highlighting connections to bronze-working and linguistic clues. However, another scholar raises objections to these conclusions. The article provides a comprehensive analysis of the different interpretations and offers further sources for research on Mycenaean Greek. [Extracted from the article]

With a current global estimation of 600–700 individuals, Monachus monachus is considered among the most threatened seal species globally and is ranked as "Endangered" by the IUCN Red List of Threatened Species. The Mediterranean distribution of the species is fragmented, and the largest known sub-population inhabits its easternmost areas. The present study analyses the occurrence of M. monachus on Samos Island, in the north-eastern Aegean Sea, Greece. From May 2017 to November 2019, data were collected through a combination of monitoring approaches, including visual monitoring from a land position, opportunistic sightings collected by citizen science, and data of stranded individuals. Results indicate the constant occurrence of monk seals in the waters and coastal areas of Samos Island, confirming the importance of this area for conservation purposes. Furthermore, the results show that an integrated methodological approach can contribute to enhancing and increasing data collection, representing an effective method for conservation studies. This approach could be applied in other locations, allowing the scientific community to identify regions of interest, where to expand targeted monitoring and apply conservation measures. [ABSTRACT FROM AUTHOR]

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Simple Summary: Modern zoos and aquariums are defined by several goals, which include improving the welfare of their animals, conservation efforts, public education, research, and visitor enjoyment. Animal-Visitor Interactions (AVIs) are a means to study the outcomes of some of these goals. These outcomes can be measured in terms of visitor effects (the effects of the visitors on the exhibited animals) and visitor experiences (the effects of the animals and the institution itself on the visitors). Additionally, new animal introductions have been examined for their effects on animals, but little has been done to measure the introduction visitor experience. The purpose of this study was to observe the effects of new animal introductions at two exhibits on both animal and visitor activity. Changes in existing animals' behaviors and visitor crowd size and length of stay were measured before and after new animal introductions. The introduction had neutral to positive impacts on both variables, suggesting potential benefits on AVIs based on new animal introductions. Such studies could help establish best practices for new animal introductions and ways to promote positive AVIs within a zoo/aquarium setting. Modern zoos and aquariums are defined by several primary goals, which include improving the welfare of their animals, public education, and inspiring visitors to develop an interest in conservation. Animal-Visitor Interactions (AVIs) (i.e., the impact of captive animals and visitors on each other) are a primary means to study these goals. The introduction of new animals into two seal exhibits—the harbor and northern fur seals—at the Seattle Aquarium presented a valuable opportunity to assess the impacts of introductions on the currently exhibited animals and aquarium visitors. The impacts of animal introductions were measured through direct observations of seal activity (i.e., ethogram behavioral observations) and visitor activity (i.e., crowd size and visitor length of stay) before and after new seal introductions. This study consisted of two experiments: Experiment 1 (Harbor seal exhibit) and Experiment 2 (Northern fur seal exhibit). In Experiment 1, we found that the introduction had few impacts on the existing harbor seals or on visitor activity. In Experiment 2, the introduction of a new fur seal had significant positive impacts on the existing fur seal, as was seen through increased social behaviors and decreased stereotypic behaviors, as well as a significant increase in crowd size post-introduction. Based on these findings, new animal introductions were associated with neutral to positive changes in both seal and visitor activity. Findings from this study suggest that studying new animal introductions can result in better understanding and promoting positive interactions with existing animals (introduction effects) and likewise positive experiences for zoo and aquarium visitors (introduction experiences). [ABSTRACT FROM AUTHOR]

In recent decades, the amount of marine debris has increased in our oceans. As wildlife interactions with debris increase, so does the number of entangled animals, impairing normal behavior and potentially affecting the survival of these individuals. The current study summarizes data on two phocid species, harbor (Phoca vitulina) and gray seals (Halichoerus grypus), affected by marine debris in Dutch waters from 2010 to 2020. The findings indicate that the annual entanglement rate (13.2 entanglements/year) has quadrupled compared with previous studies. Young seals, particularly gray seals, are the most affected individuals, with most animals found or sighted with fishing nets wrapped around their necks. Interestingly, harbor seals showed a higher incidence of ingested debris. Species differences with regard to behavior, foraging strategies, and habitat preferences may explain these findings. The lack of consistency across reports suggests that it is important to standardize data collection from now on. Despite increased public awareness about the adverse environmental effects of marine debris, more initiatives and policies are needed to ensure the protection of the marine environment in the Netherlands. [ABSTRACT FROM AUTHOR]

The fossil remains of a seal of the genus Pachyphoca from the Upper Miocene Sarmatian stratum of the Morskaya-3 site (Neklinovskii district, Rostov region) were described. According to the structure of the humerus and pelvic bones, the seal was identified as Pachyphocaukrainica Koretsky et Rahmat, 2013. This is the first evidence of the presence of representatives of this genus in northeast of Taganrog Bay, demonstrating the similar composition of the Middle Sarmatian fauna of marine mammals in the western and eastern districts of the Northern Black Sea region. [ABSTRACT FROM AUTHOR]

Peri‐ and postoperative anastomotic leakage from blood vessel anastomosis is a common and potentially life‐threatening complication. As an adjunctive therapy providing an additional layer of safety, a new biodegradable, polyurethane‐based adhesive was developed. It consists of two components: an isocyanate‐functionalized prepolymer and an amino‐based curing agent. The adhesive was investigated in a porcine animal model to seal sutured blood vessel anastomoses of arteries, veins, aortas and prosthetic aortic graft replacements. The material‐determined properties of the adhesive like viscosity, processing and polymerization time as well as bonding strength were well suited for this application. The adhesive stopped perioperative suture‐line bleedings and stayed on all anastomoses until sacrifice. Hematological and serological inflammation marker assessments were unobtrusive. The histological evaluation showed a mild to moderate local tissue reaction to the adhesive constituting a physiological, non‐adverse tissue‐biomaterial interaction. The adhesive did not interfere with vascular wound healing. The adhesive demonstrated to be suitable to improve the outcome of cardiovascular surgeries by securing the classical sutured anastomoses in a fast, easy and safe manner. However, further studies are required to quantitatively evaluate efficacy in terms of anastomotic leakage prevention as well as long‐term tissue compatibility and degradation. [ABSTRACT FROM AUTHOR]

The protection which the law gives animals is based on a fundamentally different philosophy to that it gives people. With people, causing significant physical harm is nearly always prohibited, irrespective of any benefit which might accrue to others. By contrast, animals' essential interests are weighed against a wide range of human interests, and usually they lose out. That routinely means that significant harm is inflicted on them, quite legally. Many consider that there is therefore a pressing need for lawyers committed to maximising the protection which animals receive. This article discusses the numerous ways in which lawyers can help animal protection organisations realise their goals, with two case studies. The first relates to the global trade in seal products and the second to the legal status of domesticated animals as chattels and the implications this has for their welfare. [ABSTRACT FROM AUTHOR]

Harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) both occur within the UK, but display regional contrasting population trends. While grey seals are typically increasing in number, harbour seals have shown varying trends in recent decades following repeated pandemics. There is a need for monitoring of regional and local populations to understand overall trends. This study utilized a 20‐year dataset of seal counts from two neighboring harbours in the Solent region of south England. Generalized additive models showed a significant increase in the numbers of harbour (mean 5.3–30.5) and grey (mean 0–12.0) seals utilizing Chichester Harbour. Conversely, in Langstone Harbour there has been a slight decrease in the number of harbour seals (mean 5.3–4.0). Accompanying photographic data from 2016 to 18 supports the increase in seal numbers within Chichester Harbour, with a total of 68 harbour and 8 grey seals identified. These data also show evidence of site fidelity of harbour seals in this area, with almost a quarter of animals resighted within the past three years. Overall, this long‐term study indicates an increasing number of both harbour and grey seals within the Solent. However, more research is required to identify the drivers of this trend. [ABSTRACT FROM AUTHOR]

Suction is widely used by animals for strong controllable underwater adhesion but is less well understood than adhesion of terrestrial climbing animals. Here we investigate the attachment of aquatic insect larvae (Blephariceridae), which cling to rocks in torrential streams using the only known muscle-actuated suction organs in insects. We measured their attachment forces on well-defined rough substrates and found that their adhesion was less reduced by micro-roughness than that of terrestrial climbing insects. In vivo visualisation of the suction organs in contact with microstructured substrates revealed that they can mould around large asperities to form a seal. We have shown that the ventral surface of the suction disc is covered by dense arrays of microtrichia, which are stiff spine-like cuticular structures that only make tip contact. Our results demonstrate the impressive performance and versatility of blepharicerid suction organs and highlight their potential as a study system to explore biological suction mechanisms. [ABSTRACT FROM AUTHOR]

The quantitative use of stable isotopes (SIs) for trophic studies has seen a rapid growth whereas fatty acid (FA) studies remain mostly qualitative. We apply the Bayesian tool MixSIAR to both SI and FA data to estimate the diet of three sympatric predators: the crabeater (Lobodon carcinophaga), Weddell (Leptonychotes weddellii) and leopard seal (Hydrurga leptonyx). We used SI data of their vibrissae and FA data of their outer blubber to produce comparable diet estimates for the same individuals. Both SI and FA models predicted the same main diet components, although the predicted proportions differed. For the crabeater seal, both methods identified krill, Euphausia superba, as the main, and almost exclusive, food item, although the FA model estimated a slightly lower proportion, potentially due to the low lipid content of krill compared to the fish species used in the model. For the Weddell seal the FA model identified the fish Pleuragramma antarcticum as the most important prey, whereas the SI model was not able to distinguish among prey species, identifying a 'fish-squid' group as the main diet component. For the leopard seal, both models identified krill as the main contributor; however, the predicted proportions for the secondary sources differed. Although vibrissae and outer blubber may not represent the same timeframe, the use of MixSIAR with FA data provides diet estimates comparable to those obtained with SI data, thus, both approaches were complimentary. The use of both biotracers offers a feasible option to study diets of wild animals in a quantitative manner. [ABSTRACT FROM AUTHOR]

The polar bear Ursus maritimus is one of the species most endangered by the rapidly declining sea–ice cover in the Arctic, which they use as a platform to hunt fatty, high-energy seals. In recent decades, more polar bears have been forced to remain longer on land, so their access to seals is limited. The importance of terrestrial food to polar bears is disputable, and more data are needed. Terrestrial ungulates could be an attractive substitute prey for them. Svalbard reindeer Rangifer tarandus platyrhynchus are prevalent and their distribution is completely within the range of polar bears. They constitute an attractive potential prey offering a significant energy return. Pre-2000 sources state that polar bears do not attack Svalbard reindeer. This report is the first description and documentation of the complete course of a polar bear hunt for adult reindeer in Hornsund, SW Spitsbergen, and also of the bear's hunting behaviour and the reindeer's response. Further, we report several other recent instances of bear–reindeer interactions in Svalbard, suggesting that polar bears now hunt reindeer more frequently than they used to. This increase in hunting is probably linked to the reduced ice cover, with bears spending more time on land, and a growing reindeer population. This study adds to earlier papers on how polar bears in Svalbard have increasingly shifted to a more terrestrial diet, and indicates that they may have an enhanced role as an apex predator in the terrestrial ecosystem. [ABSTRACT FROM AUTHOR]

Pinnipeds have been identified as one of the best available models for the study of vocal learning. Experimental evidence for their learning skills is demonstrated with advanced copying skills, particularly in formant structure when copying human speech sounds and melodies. By contrast, almost no data are available on how learning skills are used in their own communication systems. We investigated the impact of playing modified seal sounds in a breeding colony of grey seals (Halichoerus grypus) to study how acoustic input influenced vocal development of eight pups. Sequences of two or three seal pup calls were edited so that the average peak frequency between calls in a sequence changed up or down. We found that seals copied the specific stimuli played to them and that copies became more accurate over time. The differential response of different groups showed that vocal production learning was used to achieve conformity, suggesting that geographical variation in seal calls can be caused by horizontal cultural transmission. While learning of pup calls appears to have few benefits, we suggest that it also affects the development of the adult repertoire, which may facilitate social interactions such as mate choice. This article is part of the theme issue 'Vocal learning in animals and humans'. [ABSTRACT FROM AUTHOR]

Despite the important role that vocal communication plays in the social lives of nearly all mammals, few studies have documented the emergence and development of acoustic behavior within individuals throughout their lifetimes. It is even less common to examine learned vs innate aspects of vocal development in long-lived mammals. In this study, we routinely monitored spontaneous vocalizations produced by a male Pacific harbor seal (Phoca vitulina) and a female northern elephant seal (Mirounga angustirostris) raised in human care without conspecific individuals for more than 18 years. We used these unique longitudinal datasets to assess whether the call characteristics of captive individuals resembled those of wild conspecific seals. Additionally, we marked the developmental onset and seasonal timing of vocal activity to determine whether initial vocal expression coincided with reproductive maturity and to evaluate whether temporal patterns in vocal activity were similar across years. We found that resemblance of vocal behavior to that of wild individuals varied between subjects. Both seals showed appropriate maturational timing of vocal behavior associated with reproductive status. The male harbor seal showed a species-typical template for vocal production, whereas the female northern elephant seal produced calls with structure that differed considerably from those of wild individuals. These two case studies provide information relevant to ongoing studies on the ontogeny of sound production and the role that learning plays in vocal behavior. [ABSTRACT FROM AUTHOR]

Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasingly considered potential competitors, especially since recent local declines in harbour seal numbers while grey seal numbers remained stable or increased at their European core distributions. A better understanding of the interactions between these species is critical for conservation efforts. This study aimed to identify the trophic niche overlap between harbour and grey seals at the southern limit of their European range, in the Baie de Somme (BDS, Eastern English Channel, France), where numbers of resident harbour seals and visiting grey seals are increasing exponentially. Dietary overlap was identified from scat contents using hierarchical clustering. Isotopic niche overlap was quantified using δ13C and δ15N isotopic values from whiskers of 18 individuals, by estimating isotopic standard ellipses with a novel hierarchical model developed in a Bayesian framework to consider both intraindividual variability and interindividual variability. Foraging areas of these individuals were identified from telemetry data. The three independent approaches provided converging results, revealing a high trophic niche overlap due to consumption of benthic flatfish. Two diet clusters were dominated by either small or large benthic flatfish; these comprised 85.5% [CI95%: 80.3%–90.2%] of harbour seal scats and 46.8% [35.1%–58.4%] of grey seal scats. The narrower isotopic niche of harbour seals was nested within that of grey seals (58.2% [22.7%–100%] overlap). Grey seals with isotopic values similar to harbour seals foraged in coastal waters close to the BDS alike harbour seals did, suggesting the niche overlap may be due to individual grey seal strategies. Our findings therefore provide the basis for potential competition between both species (foraging on benthic flatfish close to the BDS). We suggest that a continued increase in seal numbers and/or a decrease in flatfish supply in this area could cause/amplify competitive interactions and have deleterious effects on harbour seal colonies. [ABSTRACT FROM AUTHOR]

Harbor seals (Phoca vitulina richardii) in the inland waters of Washington were reduced by predator control programs in the twentieth century, but stocks have rebounded since being protected in the 1970s. Three management stocks are recognized, but there is little information on their current abundance. We conducted 38,431 km of aerial line-transect surveys throughout the range of these stocks in 2013–2016, sighting a total of 4,678 groups of harbor seals. Line-transect analysis with Beaufort sea state as a covariate provided estimates of the number of seals in the water. We then incorporated tagging data from 15 instrumented seals to develop correction factors, both for seals missed in the water while diving, and those that were on shore. Tagging data were modeled with generalized linear mixed models to provide estimates of the proportions diving and hauled out. After applying these correction factors, we estimated that the Hood Canal stock contained 1,368 seals (CV = 16.8%), the Southern Puget Sound stock contained 1,976 seals (CV = 20.5%), and the Washington Northern Inland Waters stock contained 7,513 seals (CV = 11.5%). This study presents a non-traditional approach to estimating the size of Washington inland waters harbor seal stocks, which may also be applicable to other species for which survey and tagging data are available. [ABSTRACT FROM AUTHOR]

Central place foragers are expected to offset travel costs between a central place and foraging areas by targeting productive feeding zones. Harbour seals (Phoca vitulina) make multi-day foraging trips away from coastal haul-out sites presumably to target rich food resources, but periodic track points from telemetry tags may be insufficient to infer reliably where, and how often, foraging takes place. To study foraging behaviour during offshore trips, and assess what factors limit trip duration, we equipped harbour seals in the German Wadden Sea with high-resolution multi-sensor bio-logging tags, recording 12 offshore trips from 8 seals. Using acceleration transients as a proxy for prey capture attempts, we found that foraging rates during travel to and from offshore sites were comparable to offshore rates. Offshore foraging trips may, therefore, reflect avoidance of intra-specific competition rather than presence of offshore foraging hotspots. Time spent resting increased by approx. 37 min/day during trips suggesting that a resting deficit rather than patch depletion may influence trip length. Foraging rates were only weakly correlated with surface movement patterns highlighting the value of integrating multi-sensor data from on-animal bio-logging tags (GPS, depth, accelerometers and magnetometers) to infer behaviour and habitat use. [ABSTRACT FROM AUTHOR]

The largest multispecies haulout of true seals at Sakhalin Island (Sea of Okhotsk) is located in the mouth of Piltun Bay. It is comprised of ringed (Pusa hispida), spotted (Phoca largha), and bearded (Erignathus barbatus) seals and can include as many as 2,500 animals at one time. Spotted seals numerically dominate the haulout, but ringed seals can also make a notable contribution into the structure and general dynamics of the entire pinniped aggregation during some periods of the year. The haulout is used by ringed seals throughout the ice-free period from June through October. The pattern of haulout occupancy by seal species was studied from 2014 to 2017. Seasonal variations in the number of ringed seals followed a general pattern: annually, the seasonal maximum in number of seals were recorded from the last 10 days of August to the first 10 days of October. This is the period when numerous species of small- and medium-sized fish become abundant in the mouth of Piltun Bay and in the adjacent waters of the Sea of Okhotsk. These fish species constitute the major portion of ringed seal diet throughout its range. The number of ringed seals in the study area has remained stable over the past two decades. [ABSTRACT FROM AUTHOR]

Cetacean morbilliviruses (CeMVs) are significant causes of mortality in many cetacean species in epizootics and smaller outbreaks. Despite the prominence of skin lesions in seals and terrestrial animals, including humans, affected by other morbilliviruses, they have not been reported in CeMV-infected cetaceans. Here we report CeMV-associated skin lesions in a fin whale (Balaenoptera physalus) with subacute, systemic CeMV infection that live-stranded in Scotland, UK. Grossly, the skin was sloughing in large sheets, presumed due to autolysis, but histological examination showed syncytia, below the dermoepidermal junction, that were strongly immunopositive for morbillivirus antigen, as were syncytia in other organs. By polymerase chain reaction (PCR), the relative load of CeMV-specific RNA was largest in the liver and urinary bladder, even in formalin-fixed, paraffin-wax embedded samples. Levels were low in skin and only detectable in frozen samples. Genetic comparison of the CeMV revealed close alignment with isolates from fin whales from the North Atlantic Ocean and Mediterranean Sea, but that it was distinct from the porpoise CeMV clade. These findings show skin samples can be used to diagnose CeMV infection in cetaceans, highlighting the potential of ante-mortem sampling for monitoring disease in current populations and assessment of changes in host and pathogen genetics. [ABSTRACT FROM AUTHOR]

Two of the Antarctic pack ice seals, Ross, Ommatophoca rossii, and leopard, Hydrurga leptonyx, seals, are extremely difficult to study via traditional visual survey techniques, yet are ideal for an acoustic survey as they are highly vociferous and produce an array of underwater sounds during the austral summer. To determine their acoustic occurrence in the Antarctic pack ice, we use their calls, detected within 680 acoustic recordings made between 1999 and 2009 as part of two multinational programmes. Siren calls of Ross seals were detected mainly in January, and 9.88 calls per minute from low siren calls was the highest call rate for this species. High numbers of Ross seal calls were detected close to the ice edge in areas between 0° and 20° E and 60° and 130° E, suggesting these are important summer habitats. Leopard seal calls were detected mainly in December and January, and December had the highest percentage of calls. Call rate of 11.93 calls per minute from low double trills was the highest call rate for leopard seals. Leopard seal calls were detected throughout the Southern Ocean with more calls detected throughout the pack ice. There was little spatio-temporal overlap in call occurrence of Ross and leopard seals, but both species were more vocally active during the day. Longitude and latitude were the most important predictors of Ross seal occurrence, and month of the year highly predicted leopard seal occurrence. This is the first study to examine the circumpolar acoustic occurrence of Ross and leopard seals in the Southern Ocean pack ice. [ABSTRACT FROM AUTHOR]

Despite the large number of harbor seals (Phoca vitulina richardii) rehabilitated worldwide, few studies have been conducted on postrelease movement and behavior of rehabilitated harbor seal pups. We compared interannual differences in movements and survival of 24 rehabilitated seal pups released in the Salish Sea in 2010 (n = 10), 2012 (n = 5), 2013 (n = 5), and 2014 (n = 4). We also compared the postrelease movement of these seals to the movement of 10 wild seal pups tracked in the same ecosystem in 2010. Transmission duration, total cumulative distance, and average daily distance varied annually. Maximum linear distance traveled from the release site was similar for the rehabilitated seal groups. Compared to wild seals (n = 10), and consistent with prior studies, rehabilitated pups (n = 24) traveled significantly farther daily and cumulatively than wild weaned pups. Unlike in a prior study in this ecosystem, we found no significant difference between transmission duration in wild and rehabilitated pups. [ABSTRACT FROM AUTHOR]

During the past decade, attacks by grey seals on fishing nets in the Baltic Sea have caused considerable loss of fish catch and damage to fishing gears. One of the approaches to reduce the number of seal attacks on fishing nets is to use acoustic deterrent devices (ADDs). Unfortunately, most of the commercially available ADDs are not well suited to the deployment in the sea and require considerable additional investments. The objective of the present research is to develop a compact and cost-efficient ADD for deployment in the sea environment. This paper is devoted to the design of acoustic signals for a prototype ADD. Signals from other experimental and commercially available ADDs are studied and compared. Moreover, limitations imposed by the underwater environment, transducers, battery power, and fish hearing are analysed and considered during the development of signal patterns. The results of tests conducted in an artificial reservoir and in the sea are presented. [ABSTRACT FROM AUTHOR]

Risks arising for humans during swim encounters with seals are poorly understood. This study was initiated to examine behaviors of unhabituated grey seals addressed towards humans during experimental, noncommercial seal-swim activities off Heligoland. In total, 26 in-water encounters were conducted. Behavioral classes and the number of seals simultaneously approaching swimmers were time sampled. A set of risky and nonrisky interactive behaviors was continuously sampled. Seals spent approximately the same amount of time interacting with swimmers (53%) as they did ignoring them (47%). Seals displayed higher rates of nonrisky behaviors than risky ones, but risky behaviors occurred during 73% of all seal-swims. Seals remained ≤20 m near swimmers for 51% and ≤1 m for 13% of the time. A mean number of 0.65 and 0.18 seals approached swimmers per minute within a range of ≤20 m and ≤1 m, respectively. Behavioral classes, interactive behaviors, and the number of seals approaching ≤20 m did not vary significantly throughout seal-swims but the number of seals approaching ≤1 m moderately decreased. Due to high rates of risky behaviors, it is recommended to promote public awareness on site and to regulate seal-swims before commercial operations emerge. [ABSTRACT FROM AUTHOR]

There is high spatial overlap between grey seals and shipping traffic, and the functional hearing range of grey seals indicates sensitivity to underwater noise emitted by ships. However, there is still very little data regarding the exposure of grey seals to shipping noise, constraining effective policy decisions. Particularly, there are few predictions that consider the at-sea movement of seals. Consequently, this study aimed to predict the exposure of adult grey seals and pups to shipping noise along a three-dimensional movement track, and assess the influence of shipping characteristics on sound exposure levels. Using ship location data, a ship source model, and the acoustic propagation model, RAMSurf, this study estimated weighted 24-h sound exposure levels (10–1000 Hz) (SELw). Median predicted 24-h SELw was 128 and 142 dB re 1 μPa2s for the pups and adults, respectively. The predicted exposure of seals to shipping noise did not exceed best evidence thresholds for temporary threshold shift. Exposure was mediated by the number of ships, ship source level, the distance between seals and ships, and the at-sea behaviour of the seals. The results can inform regulatory planning related to anthropogenic pressures on seal populations. [ABSTRACT FROM AUTHOR]

Lice from family Echinophthiriidae are of the few insects that have successfully colonized marine environment living as ectoparasites of pinnipeds, i.e., sea lions, seals, and the walrus. They have developed unique adaptations to cope with the amphibious lifestyle of their hosts. Because eggs do not survive underwater, lice could only reproduce when their host remains on pack ice enough time. Consequently, lice generations per year are limited by host haul-out behavior. The objective of this work is to study the effect of host sex and age class, and the annual variation on the prevalence and mean abundance of Antarctophthirus lobodontis in crabeater seals from the Antarctic Peninsula. During three consecutive field-seasons, we collected lice from 41 crabeater seals (23 females, 16 males, 2 indeterminate, being 24 adults, and 17 juveniles). We investigated this effect on the prevalence and mean abundance by a generalized linear model formulation in a Bayesian framework. According to the lowest Deviance Index Criterion model, sex host does not affect prevalence nor mean abundance. We found that juveniles present greater abundance and prevalence than adults, possibly due to foraging habits. They spent more time on the ice than adults in groups of dozens of animals. This behavior would favor both egg development and lice transmission. We do not find adult females with lice, which suggests that transmission of A. lobodontis should be horizontal. The high mean abundance of lice in 2014 could be associated with an unusual increase in Lobodon carcinophaga population, probably related to the pack-ice availability and zooplankton abundance. [ABSTRACT FROM AUTHOR]

An 88.5 cm long, 12.9 kg, 3-week-old stranded male Atlantic harbour seal (Phoca vitulina concolor) presented with cerebellar ataxia, delayed postural reactions, hyperaesthesia and nystagmus. The skull was enlarged and domed. Ultrasound through a persistent fontanelle in the frontal bone revealed hydrocephalus. Magnetic resonance imaging showed diffuse enlargement of the ventricular system, an absent cerebellar vermis, hypertrophy of the choroid plexus of the fourth ventricle and enlargement of the caudal fossa. Throughout rehabilitation, the seal failed to achieve milestones critical for successful release or placement in a managed care facility, including the ability to feed independently and haul out. Three months into rehabilitation it began to regurgitate and staff had difficulty administering food to the seal. The seal was euthanized due to a poor prognosis. Post-mortem examination confirmed a) aplasia of the dorsal cerebellar vermis and hypoplasia of the most dorsal portions of the right and left cerebellar hemispheres, b) severe, diffuse, congenital communicating hydrocephalus, and c) aplasia of the interthalamic adhesion and corpus callosum. This case represents the first report of Dandy–Walker-like malformation (DWLM) in a marine mammal and illustrates the importance of advanced imaging and thorough post-mortem examination in free-ranging pinnipeds that strand with evidence of neurological disease. [ABSTRACT FROM AUTHOR]