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Tropical ecosystems are challenging for pinnipeds due to fluctuating food availability. According to previous research, the Galapagos sea lion (GSL, Zalophus wollebaeki) adopts trophic flexibility to face such conditions. However, this hypothesis comes from studies using traditional methods (hard‐parts analysis of scat and isotopic analysis from tissue). We studied the diet of five rookeries in the southeastern Galapagos bioregion (which harbors the highest GSL density), via DNA‐metabarcoding of scat samples. The DNA‐metabarcoding approach may identify consumed prey with a higher taxonomic resolution than isotopic analysis, while not depending on hard‐parts remaining through digestion. Our study included five different rookeries to look for evidence of trophic flexibility at the bioregional level. We detected 98 prey OTUs (124 scats), mostly assigned to bony‐fish taxa; we identified novel prey items, including a shark, rays, and several deep‐sea fish. Our data supported the trophic flexibility of GSL throughout the studied bioregion since different individuals from the same rookery consumed prey coming from different habitats and trophic levels. Significant diet differentiations were found among rookeries, particularly between Punta Pitt and Santa Fe. Punta Pitt rookery, with a more pronounced bathymetry and lower productivity, was distinguished by a high trophic level and consumption of a high proportion of deep‐sea prey; meanwhile, Santa Fe, located in more productive, shallow waters over the shelf, consumed a high proportion of epipelagic planktivorous fish. Geographic location and heterogeneous bathymetry of El Malecon, Española, and Floreana rookeries would allow the animals therein to access both, epipelagic prey over the shelf, and deep‐sea prey out of the shelf; this would lead to a higher prey richness and diet variability there. These findings provide evidence of GSL adopting a trophic flexibility to tune their diets to different ecological contexts. This strategy would be crucial for this endangered species to overcome the challenges faced in a habitat with fluctuating foraging conditions. [ABSTRACT FROM AUTHOR]

To determine their frequency-dependent susceptibility to noise-induced temporary hearing threshold shift (TTS), two California sea lions (Zalophus californianus) were exposed for 60 min to a continuous one-sixth-octave noise band (NB) centered at 32 kHz as the fatiguing sound, at sound pressure levels of 132 to 156 dB re 1 µPa (sound exposure levels [SELs] of 168 to 192 dB re 1 µPa2s). Using a psychoacoustic technique, TTSs were quantified at the center frequency of the fatiguing sound and at half an octave and one octave above the center frequency (at 32, 44.8, and 63 kHz). When significant TTS occurred, higher SELs resulted in greater TTSs. TTSs and hearing recovery patterns were similar in both sea lions. The mean onset of TTS1-4 min (defined as 6 dB TTS) in sea lion F01 is estimated to occur after exposure to an SEL of 179 dB re 1 µPa²s (at hearing test frequency 44.8 kHz). After exposure to an SEL of 180 dB re 1 µPa2s, a mean TTS1-4 min of 6.7 dB was measured at hearing test frequency 44.8 kHz. In California sea lions, TTS onset levels are not as closely related (especially at the lower and higher frequencies) to the unmasked hearing thresholds (audiograms) as was previously assumed. [ABSTRACT FROM AUTHOR]

This article presents a case study of dental procedures performed on two California sea lions. The study provides detailed clinical, radiographic, and histological findings of the teeth in these sea lions, highlighting the presence of endodontic disease and pulp exposure. The authors suggest considering alternatives to dental extractions, such as endodontic treatment, and emphasize the importance of dental radiographs in sea lion examinations. They also mention alternative treatments to extraction, such as vital pulpectomy, particularly for immature permanent canine teeth with chronic hyperplastic pulpitis. [Extracted from the article]

California sea lions (Zalophus californianus) are distributed along the Gulf of California and northeastern Pacific coast. Genetic studies have suggested the existence of 3 to 4 subpopulations in Mexico—1 on the Pacific coast of the Baja California peninsula (PC) and 3 in the Gulf of California—but the extent of this divergence is unclear, and it remains unknown if these subpopulations are morphologically distinct. In this context, we analyzed variation in skull size and shape of adult males between 5 and 13 years of age among 2 (north and central) of the 3 subpopulations of Z. californianus from the Gulf of California and the PC in Mexico. However, since the sample sizes for the 2 subpopulations in the Gulf of California were small, we merged all samples into 1 that we called the Gulf of California (GC) subpopulation. Artificial neural networks and geometric morphometrics were used to analyze skull images to quantify the extent to which these geographically separated subpopulations are undergoing morphological divergence. Our results find no significant differences in size in any view between the 2 subpopulations, but significant differences in the morphology of the dorsal, ventral, and lateral views of the skull between the 2 subpopulations. Overall, Z. californianus from the GC subpopulation have wider and lower skulls, extended back and outward with a more voluminous (bulky) nuchal crest, and narrow rostrum in comparison with skulls of Z. californianus from the PC subpopulation. Results concur with a previous genetic-based study, demonstrating that Z. californianus from both subpopulations in Mexico are diverging in their skull morphology and perhaps suggesting that they are experiencing different evolutionary pressures. [ABSTRACT FROM AUTHOR]

The goal of this study was to characterize the cardiorespiratory patterns of male South American sea lions (SASLs, Otaria flavescens) resting on land. We recorded respiratory and heart rate (n = 360 individuals studied) by observing the nostrils, chest movements and the impact of the heart on the thoracic wall. The sea lions breathe apneustically with a pause on inspiration, representing 74% of the respiratory cycle. The mean breathing frequency was 3.2 ± 1.0 breaths min−1, with a breathing cycle presenting periods of bradypneas, tachypneas, and long-term post-inspiratory pauses. The normal heart rate (nHR) was 73.4 ± 14.5 beats min−1 and no significant differences were observed between age classes. All animals showed variability in HR in relation to respiratory phases (Inspiration: 101.2 ± 18.4 beats min−1; post-inspiratory pause: 73.4 ± 14.5 beats min−1; expiration: 64.6 ± 17.7 beats min−1), consistent with respiratory sinus arrhythmia (RSA). The mean HR (measured during all respiratory phases) was 79.9 ± 22.7 beats min−1, and was significantly different between age classes. The total duration of respiratory cycle, and duration of both inspiration and expiration, decreased with an increment in ambient temperature, with no variation in the pause duration. Heart rate during pause and expiration was significantly higher during high temperatures. Similar changes in cardiorespiratory patterns have been reported in other pinnipeds. Our results showed ontogenetic differences in development and typical variations with environmental and behavioral variables. [ABSTRACT FROM AUTHOR]

The authors present multiple machine learning‐based methods for distinguishing maritime targets from sea clutter. The main goal for this classification framework is to aid future millimetre wave radar system design for marine autonomy. Availability of empirical data at this frequency range in the literature is scarce. The classification and anomaly detection techniques reported here use experimental data collected from three different field trials from three different millimetre wave radars. Two W‐band radars operating at 77 and 94 GHz and a G‐band radar operating at 207 GHz were used for the field trial data collection. The dataset encompasses eight classes including sea clutter returns. The other targets are boat, stand up paddleboard/kayak, swimmer, buoy, pallet, stationary solid object (i.e. rock) and sea lion. The Doppler signatures of the targets have been investigated to generate feature values. Five feature values have been extracted from Doppler spectra and four feature values from Doppler spectrograms. The features were trained on a supervised learning model for classification as well as an unsupervised model for anomaly detection. The supervised learning was performed for both multi‐class and 2‐class (sea clutter and target) classification. The classification based on spectrum features provided an 84.3% and 80.1% validation and test accuracy respectively for the multi‐class classification. For the spectrogram feature‐based learning, the validation and test accuracy for multi‐class increased to 93.3% and 88.7% respectively. For the 2‐class classification, the spectrum feature‐based training accuracies are 88.1% and 86.8%, whereas with the spectrogram feature‐based model, the values are 95% and 94.1% for validation and test accuracies respectively. A one class support vector machine was also applied to an unlabelled dataset for anomaly detection training, with 10% outlier data. The cross‐validation accuracy has shown very good agreement with the expected anomaly detection rate. [ABSTRACT FROM AUTHOR]

The identification of important habitat and the behavior(s) associated with it is critical to conservation and place‐based management decisions. Behavior also links life‐history requirements and habitat use, which are key to understanding why animals use certain habitats. Animal population studies often use tracking data to quantify space use and habitat selection, but they typically either ignore movement behavior (e.g., foraging, migrating, nesting) or adopt a two‐stage approach that can induce bias and fail to propagate uncertainty. We develop a habitat‐driven Langevin diffusion for animals that exhibit distinct movement behavior states, thereby providing a novel single‐stage statistical method for inferring behavior‐specific habitat selection and utilization distributions in continuous time. Practitioners can customize, fit, assess, and simulate our integrated model using the provided R package. Simulation experiments demonstrated that the model worked well under a range of sampling scenarios as long as observations were of sufficient temporal resolution. Our simulations also demonstrated the importance of accounting for different behaviors and the misleading inferences that can result when these are ignored. We provide case studies using plains zebra (Equus quagga) and Steller sea lion (Eumetopias jubatus) telemetry data. In the zebra example, our model identified distinct "encamped" and "exploratory" states, where the encamped state was characterized by strong selection for grassland and avoidance of other vegetation types, which may represent selection for foraging resources. In the sea lion example, our model identified distinct movement behavior modes typically associated with this marine central‐place forager and, unlike previous analyses, found foraging‐type movements to be associated with steeper offshore slopes characteristic of the continental shelf, submarine canyons, and seamounts that are believed to enhance prey concentrations. This is the first single‐stage approach for inferring behavior‐specific habitat selection and utilization distributions from tracking data that can be readily implemented with user‐friendly software. As certain behaviors are often more relevant to specific conservation or management objectives, practitioners can use our model to help inform the identification and prioritization of important habitats. Moreover, by linking individual‐level movement behaviors to population‐level spatial processes, the multistate Langevin diffusion can advance inferences at the intersection of population, movement, and landscape ecology. [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]

Seals exist at the intersection of land and water. This is especially true of eared seals (otariids), which are both highly adapted to forelimb swimming and retain the ability to walk on land. The precise nature and evolutionary history of their walking ability remains obscure, however. Here, we use axial analysis to compare the hind limb movements of California and South American sea lions with those of terrestrial plantigrades mammals. We show that, despite notable differences in foot orientation and joint position, all of our study species employ similar movements around the same centers of rotation. Our results suggest that otariid hind limbs and, in particular, the hallux play a substantial role in supporting and propelling the body during walking. [ABSTRACT FROM AUTHOR]

The excellent classification accuracy of remote sensory images has led to a major expansion of their use in agricultural field surveillance in recent years. The accurate classification of crop is very significant for agricultural management and food security. There are diverse varieties of crops are available. Among them, each possesses same spectral curves. Due to increasing number of remote sensing information, a major limitation arises in the domain of crop classification is how to determine significant data from huge volume of information to maintain categorization accuracy and implementation time. Consequently, one of the main obstacles in the agricultural industry is the precise classification of crops. Deep Residual Network (ResNet)-based Social Sea Lion Driver Optimization (SSLnDO)-based Deep Fuzzy Clustering (DFC), where the distance is calculated using RV coefficient, are used to develop an effective method for classifying cotton crops. Finally, classification of the cotton crop is successfully accomplished using Deep ResNet, and the network classifier is trained by inserting produced SSLnDO. The vegetation index is generated for each color band independently. Combining the Social Ski Driver (SSD) optimization and the Sea Lion Optimization (SLnO) method yields the newly developed SSLnDO. A maximum testing accuracy of 0.940, a sensitivity of 0.931, and a specificity of 0.926 have been achieved by the designed model. When comparing the accuracy value produced by the proposed method for image-2 to the existing approaches, namely WLI-Fuzzy + BS-Lion NN, OSVM-OCNN, GAN, Hybrid CNN-RF, Deep learning, and Deep ResNet, they are 15.21%, 11.06%, 15.21%, 9.04%, 4.36%, and 2.3% higher. [ABSTRACT FROM AUTHOR]

Phocine distemper virus (PDV) is a significant cause of mortality for phocid seals; however, the susceptibility of otariids to this virus is poorly understood. The authors used a lymph-node explant culture system from California sea lions (Zalophus californianus, CSL) to investigate: (1) the role of signaling lymphocyte activation molecule (SLAM) and nectin-4 in PDV infection and their cellular expression patterns, (2) if PDV induces transcriptional regulation of cell-entry receptors, and (3) the involvement of apoptosis in PDV infection. PDV replicated in the lymph-node explants with peak replication 3 days post-infection (dpi), but the replication was not sustained 4 to 5 dpi. The PDV+ cells co-localized SLAM and nectin-4. These cells expressed IBA1, indicating a histiocytic lineage. Comparison of receptor expression between infected and mock-infected lymph nodes suggested transcriptional downregulation of both receptors during the initial stage of infection and upregulation during the late stage of infection, but the values lack of statistical significance. Cleaved caspase-3+ cells were slightly increased in the infected lymph nodes compared with the mock-infected lymph node from 1 to 4 dpi, but without statistical significance, and a few apoptotic cells co-expressed PDV. The results suggest that lymph-node explants might be an important model to study PDV pathogenesis. CSLs have the potential to be infected with PDV, as they express both cell-entry receptors in histiocytes. The lack of statistical significance in the PDV replication, transcriptional regulation of viral receptors, and changes in apoptosis suggest that although CSL might be infected by PDV, they might be less susceptible than phocid species. [ABSTRACT FROM AUTHOR]

Abstract Establishing marine species distributions is essential for guiding management and can be estimated by identifying potential favorable habitat at a population level and incorporating individual‐level information (e.g., movement constraints) to inform realized space use. In this research, we applied a combined modeling approach to tracking data of adult female and juvenile South American sea lions (Otaria flavescens; n = 9) from July to November 2011 to make habitat predictions for populations in northern Chile. We incorporated topographic and oceanographic predictors with sea lion locations and environmentally based pseudo‐absences in a generalized linear model for estimating population‐level distribution. For the individual approach, we used a generalized linear mixed‐effects model with a negative exponential kernel variable to quantify distance‐dependent movement from the colony. Spatial predictions from both approaches were combined in a bivariate color map to identify areas of agreement. We then used a GIS‐based risk model to characterize bycatch risk in industrial and artisanal purse‐seine fisheries based on fishing set data from scientific observers and artisanal fleet logs (2010–2015), the bivariate sea lion distribution map, and criteria ratings of interaction characteristics. Our results indicate population‐level associations with productive, shallow, low slope waters, near to river‐mouths, and with high eddy activity. Individual distribution was restricted to shallow slopes and cool waters. Variation between approaches may reflect intrinsic factors restricting use of otherwise favorable habitat; however, sample size was limited, and additional data are needed to establish the full range of individual‐level distributions. Our bycatch risk outputs identified highest risk from industrial fisheries operating nearshore (within 5 NM) and risk was lower, overall, for the artisanal fleet. This research demonstrates the potential for integrating potential and realized distribution models within a spatial risk assessment and fills a gap in knowledge on this species' distribution, providing a basis for targeting bycatch mitigation outreach and interventions.

The resurgence of pinniped populations along the West Coast of the United States, a consequence of the Marine Mammal Protection Act, has resulted in unintended ecological and socio-economic repercussions. The conflict between pinniped and fisheries in California, a persistent management challenge for decades, primarily manifests as depredation (the removal or damage of hooked fish) from Commercial Passenger Fishing Vessels (CPFVs). Depredation not only results in stolen fish but also in lost fishing opportunities due to the presence of pinnipeds deterring target fish species or necessitating vessel relocation. Using logbook data from 1994 to 2021, we explored spatiotemporal trends in pinniped depredation of CPFVs in California. Our model, which evaluates the factors predicting the number of fish depredated, revealed a distinct concentration of pinniped depredation in Southern California, with increasing rates of depredation during summer and spring. Over our time series, depredation is decreasing, as our model found a seven percent decrease in the number of fish depredated each calendar year. Correspondingly, changepoint and trend analysis revealed two key trend reversals in 1999 and 2014, exemplified by a rapid peak and ensuing drop in overall depredation. Overall, our study suggests that depredation is shaped by an interplay of environmental factors, the population dynamics of pinnipeds, and the patterns of fishing activities within the California current ecosystem.

We report a massive mortality of 5,224 sea lions (Otaria flavescens) in Peru that seemed to be associated with highly pathogenic avian influenza A(H5N1) virus infection. The transmission pathway may have been through the close contact of sea lions with infected wild birds. We recommend evaluating potential virus transmission among sea lions.

Nasopulmonary mites (NPMs) of the family Halarachnidae are obligate endoparasites that colonize the respiratory tracts of mammals. NPMs damage surface epithelium resulting in mucosal irritation, respiratory illness, and secondary infection, yet the role of NPMs in facilitating pathogen invasion or dissemination between hosts remains unclear. Using 16S rRNA massively parallel amplicon sequencing of six hypervariable regions (or "16S profiling"), we characterized the bacterial community of NPMs from 4 southern sea otters (Enhydra lutris nereis). This data was paired with detection of a priority pathogen, Streptococcus phocae, from NPMs infesting 16 southern sea otters and 9 California sea lions (Zalophus californianus) using nested conventional polymerase chain reaction (nPCR). The bacteriome of assessed NPMs was dominated by Mycoplasmataceae and Vibrionaceae, but at least 16 organisms with pathogenic potential were detected as well. Importantly, S. phocae was detected in 37% of NPM by nPCR and was also detected by 16S profiling. Detection of multiple organisms with pathogenic potential in or on NPMs suggests they may act as mechanical vectors of bacterial infection for marine mammals.

We report full-genome characterization of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus from an outbreak among sea lions (August 2023) in Argentina and possible spillover to fur seals and terns. Mammalian adaptation mutations in virus isolated from marine mammals and a human in Chile were detected in mammalian and avian hosts. [ABSTRACT FROM AUTHOR]

Domoic acid-producing blooms of the diatom genus Pseudo-nitzschia are pervasive in coastal environments globally. Domoic acid, a neurotoxin, accumulates via trophic transfer into marine food webs and is often associated with mass marine mammal mortality and stranding events. In Southern California, California sea lions (Zalophus californianus) are an indicator species for food web impacts of domoic acid because they are abundant secondary consumers, sensitive to domoic acid intoxication, and are actively monitored by stranding networks. However, domoic acid exposure may occur a distance from where a sea lion ultimately strands. This spatiotemporal variation complicates coupling domoic acid observations in water to strandings. Therefore, we sought to quantify whether monitoring data from four pier sites across the region, covering nearly 700 km of coastline from 2015-2019, could be used to predict adult and subadult sea lion strandings along the 68 km Orange County coastline surveyed by the Pacific Marine Mammal Center. We found that increased sea lion strandings were often observed just prior to an increase in particulate domoic acid at the piers, confirming that clusters of subadult and adult sea lion strandings with clinical signs of domoic acid intoxication serve as indicators of bloom events. In addition, domoic acid concentrations at Stearns Wharf, nearly 200 km from stranding locations, best predicted increased total sea lion strandings, and strandings of sea lions with domoic acid intoxication symptoms. Particulate domoic acid concentrations greater than 0.05 µg/L at Stearns Wharf were linked to stranding probabilities in Orange County ranging from 2.2% to 55% per week, and concentrations of 0.25 µg/L resulted in weekly stranding probabilities ranging from 16% to 81% depending on the stranding scenario modeled. [ABSTRACT FROM AUTHOR]

Simple Summary: Over the last four decades, the Galapagos sea lion (GSL—Zalophus wollebaeki) has faced a significant population decline. An important concern is the increasing population of domestic dogs in some islands of the archipelago. These animals can be a source of various infectious diseases that can be transmitted to the GSL. An important pathogen is the canine distemper virus (CDV), causing the viral infection that generates the most concern for the agencies responsible for the management and conservation of the Galapagos pinnipeds. This virus was detected in the GSL in 2010; however, very little is known about its circulation and epidemiology. Our study tested 110 GSL serum samples that were collected during the summer of 2016 and 2017. Our results showed an increasing circulation of CDV and highlight the importance of monitoring emerging diseases that can be transmitted from the domestic to the wildlife species of the archipelago. Background: The emblematic Galapagos sea lion (GSL—Zalophus wollebaeki) has faced an important population decline over the last four decades. There are multiple environmental and biological factors that might be implied in this decrease. Recently, evidence of various zoonotic infectious diseases that can be potential threats has been reported. Considering that in some islands of the archipelago the risk of transmission of infectious diseases may be promoted by the increasing population of domestic dogs, epidemiological vigilance and search of new pathogens are essential. The canine distemper virus (CDV), one of the viral pathogens that generate the most concern for the agencies responsible for the management and conservation of the Galapagos pinnipeds, was detected in the GSL in 2010. However, there is scarce information about its impact on GSL health and about its epidemiology. Methods: In this study, 110 GSL serum samples were collected during the summer of 2016 and 2017. All samples were exposed to VERO dog SLAM cells expressing the canine SLAM receptor. Results: Our results showed a significative increase (p = 0.04) in the frequency of neutralizing antibodies to CDV in the 2017 (53.1%) samples compared to the 2016 samples (19.6%). Conclusions: Our work confirmed the continuous and increasing circulation of the CDV in the GSL and highlights the importance of monitoring emerging diseases that can be transmitted from domestic to wildlife species. Vigilance of CDV is essential to understand the role of this virus in GSL mortality and to take informed decisions for wildlife conservation. [ABSTRACT FROM AUTHOR]

California sea lions (Zalophus californianus) are susceptible to entanglement in fishing gear and marine debris. Over time, entanglement material can become deeply embedded and disrupt underlying tissue layers, including skin, blubber, muscle, and regional structures. In the neck, chronic circumferential entanglement can result in airway laceration. We present a case study of an adult female California sea lion with an upper airway stoma secondary to chronic monofilament fishing net entanglement. The animal was disentangled in a remote field setting without access to surgical and rehabilitation facilities, and was released without additional treatment. Satellite telemetry data from the 5 months following disentanglement revealed movements comparable to those of other adult female California sea lions. Subsequent visual sightings ('resights') documented a minimum 2‐year survival following disentanglement. [ABSTRACT FROM AUTHOR]

Sea lions as a group, display strong site fidelity, and varying degrees of vulnerability to environmental change, disease and fisheries interactions. One of the rarest pinnipeds, the New Zealand sea lion (NZSL, Phocarctos hookeri) has a very restricted breeding range. At Campbell Island/Motu Ihupuku, one of the two primary breeding sites, at‐sea foraging behaviour is unknown. We hypothesised that NZSL of various sex and age classes would utilise the water column differently due to differing physiological constraints and therefore have different accessibility to prey resources. We tested whether sea lion diving behaviour varied in relation to (i) age and sex class, (ii) time of day and (iii) water depth. We also hypothesised that the proportion of benthic/pelagic diving, and consequently risk of fisheries interaction, would vary in relation to age and sex. Satellite telemetry tags were deployed on 25 NZSL from a range of age/sex classes recording dive depth, duration and location. Adult females and juveniles used inshore, benthic habitats, while sub‐adult males also utilised benthic habitats, they predominantly used pelagic habitat at greater distances from the island. Adult females and juveniles exhibited shorter dives than the same age/sex classes at the Auckland Islands, suggesting a lower dive effort for these age/sex classes at Campbell Island/Motu Ihupuku. Adult females dived more frequently than other age/sex classes, likely operating closer to their physiological limits; however, further data for this age class is needed. Sub‐adult male use of pelagic prey may increase their exposure to mid‐water trawls; however, further research detailing the degree of spatial overlap with fisheries is required. This study highlights the utility of spatially explicit dive data to predict vertical habitat use, niche separation of various age and sex classes of marine predators and attribute potential fisheries interaction risk in relation to predator habitat use. [ABSTRACT FROM AUTHOR]

Nowadays, precise and up-to-date maps of road are of great significance in an extensive series of applications. However, it automatically extracts the road surfaces from high-resolution remote sensed images which will remain as a demanding issue owing to the occlusion of buildings, trees, and intricate backgrounds. In order to address these issues, a robust Gradient Descent Sea Lion Optimization-based U-Net (GDSLO-based U-Net) is developed in this research work for road outward extraction from High Resolution (HR) sensing images. The developed GDSLO algorithm is newly devised by the incorporation of Stochastic Gradient Descent (SGD) and Sea Lion Optimization Algorithm (SLnO) algorithm. Input image is pre-processed and U-Net is employed in road segmentation phase for extracting the road surfaces. Meanwhile, training data of U-Net has to be done by using the GDSLO optimization algorithm. Once road segmentation is done, road edge detection and road centerline detection is performed using Fully Convolutional Network (FCN). However, the developed GDSLO-based U-Net method achieved superior performance by containing the estimation criteria, including precision, recall, and F1-measure through highest rate of 0.887, 0.930, and 0.809, respectively. [ABSTRACT FROM AUTHOR]

In recent years, the Internet of Things (IoT) has transformed human life by improving quality of life and revolutionizing all business sectors. The sensor nodes in IoT are interconnected to ensure data transfer to the sink node over the network. Owing to limited battery power, the energy in the nodes is conserved with the help of the clustering technique in IoT. Cluster head (CH) selection is essential for extending network lifetime and throughput in clustering. In recent years, many existing optimization algorithms have been adapted to select the optimal CH to improve energy usage in network nodes. Hence, improper CH selection approaches require more extended convergence and drain sensor batteries quickly. To solve this problem, this paper proposed a coati optimization algorithm (EACH-COA) to improve network longevity and throughput by evaluating the fitness function over the residual energy (RER) and distance constraints. The proposed EACH-COA simulation was conducted in MATLAB 2019a. The potency of the EACH-COA approach was compared with those of the energy-efficient rabbit optimization algorithm (EECHS-ARO), improved sparrow optimization technique (EECHS-ISSADE), and hybrid sea lion algorithm (PDU-SLno). The proposed EACH-COA improved the network lifetime by 8–15% and throughput by 5–10%. [ABSTRACT FROM AUTHOR]

A historical example, case study 2, is one of two cases illustrating the complexity of interactions between sharks in their natural environment. Evidence is presented that the white shark is a selective feeder, consuming seals and sea lions with high fat content yet rejecting a pelican, human, and sea otters with low fat content. After biting seals, these sharks carry them in their jaws for a prolonged time underwater to kill them through blood-loss, i.e., exsanguination. Multiple sharks compete to feed on the remaining seal carcass when it floats to the surface. The sharks perform the Tail Slap, consisting of lifting the caudal fin and splashing water toward the accompanying shark. A combatant is permitted to feed further on a seal only if the vigor and frequency of its tail slaps are greater than those of its opponent. Thus, this is an agonistic display, functioning to ward off potential competitors. [ABSTRACT FROM AUTHOR]

Mobile ad hoc networks (MANET) are self-launching and self-building multichip wireless networks in which the system's construction deviates significantly owing to the mobility of the nodes. Network nodes serve as both hosts and routers, transferring data from other network nodes. MANETs necessitate an efficient routing protocol with a quality of service (QoS) component. They do not consider mobility as a potential restriction for routing concerns. It is challenging to maintain the necessary QoS in the network due to node mobility, which frequently causes connection failures and high error rates. The aim of the proposed study is to develop an effective MANET framework with dynamic routing and enhanced clustering. In this work, Fuzzy C means clustering is utilized to form the clusters identifying communities or groups of nodes with similar characteristics or behavior, whereas sea lion optimization (SLnO) is utilized to attain the best routing path for data transmission. The proposed model is empirically tested and compared with particle swarm optimization (PSO), ant colony optimization (ACO), grey wolf optimization (GWO), and genetic algorithm (GA) in terms of factors such as throughput, packet loss, energy consumed and end to end delay. The findings demonstrate that SLnO algorithm outperforms other protocols in terms of efficient routing generating a throughput of 680Mb/s and a packet delivery ratio (PDR) of 93.6%. [ABSTRACT FROM AUTHOR]

The goal of this work is to reduce power loss and improve voltage profile by formulating the optimal DG placement problem as a restricted nonlinear optimisation problem. As a novelty, the proposed hybrid algorithm, referred to as Multifactor Update-based Hybrid Model (MUHM) is constructed by merging the concepts of Lion Algorithm (LA) & Sea Lion Algorithm (Sea Lion Optimization Algorithm (SLnO). The Forward-Backward Sweep (FBSM) Model is used to calculate the power loss. Three test cases are examined for the voltage profile & loss minimization in the feeder team with DGs: "case 1(DG supplying real power alone (P), case 2 (DG supplying reactive power alone (Q) and Case 3 (DG supplying both real and reactive power)". Application of the suggested method to various IEEE test systems, including IEEE 33, IEEE 123, and IEEE 69, respectively, is used to assess its efficacy. According, the results show that the presented work at loading percentage = 0 is 12, 15, 135, 4.65, and 8 superior to SFF, BBO, BAT, LA and SLnO, respectively. [ABSTRACT FROM AUTHOR]

An intense public debate has fuelled governmental bans on marine mammals held in zoological institutions. The debate rests on the assumption that survival in zoological institutions has been and remains lower than in the wild, albeit the scientific evidence in support of this notion is equivocal. Here, we used statistical methods previously applied to assess historical improvements in human lifespan and data on 8864 individuals of four marine mammal species (harbour seal, Phoca vitulina; California sea lion, Zalophus californianus; polar bear, Ursus maritimus; common bottlenose dolphin, Tursiops truncatus) held in zoos from 1829 to 2020. We found that life expectancy increased up to 3.40 times, and first-year mortality declined up to 31%, during the last century in zoos. Moreover, the life expectancy of animals in zoos is currently 1.65–3.55 times longer than their wild counterparts. Like humans, these improvements have occurred concurrently with advances in management practices, crucial for population welfare. Science-based decisions will help effective legislative changes and ensure better implementation of animal care. [ABSTRACT FROM AUTHOR]

Introduction: Viral diseases of marine mammals are difficult to study, and this has led to a limited knowledge on emerging known and unknown viruses which are ongoing threats to animal health. Viruses are the leading cause of infectious disease-induced mass mortality events among marine mammals. Methods: In this study, we performed viral metagenomics in stool and serum samples from California sea lions (Zalophus californianus) and bottlenose dolphins (Tursiops truncates) using long-read nanopore sequencing. Two widely used long-read de novo assemblers, Canu and Metaflye, were evaluated to assemble viral metagenomic sequencing reads from marine mammals. Results: Both Metaflye and Canu assembled similar viral contigs of vertebrates, such as Parvoviridae, and Poxviridae. Metaflye assembled viral contigs that aligned with one viral family that was not reproduced by Canu, while Canu assembled viral contigs that aligned with seven viral families that was not reproduced by Metaflye. Only Canu assembled viral contigs from dolphin and sea lion fecal samples that matched both protein and nucleotide RefSeq viral databases using BLASTx and BLASTn for Anelloviridae, Parvoviridae and Circoviridae families. Viral contigs assembled with Canu aligned with torque teno viruses and anelloviruses from vertebrate hosts. Viruses associated with invertebrate hosts including densoviruses, Ambidensovirus, and various Circoviridae isolates were also aligned. Some of the invertebrate and vertebrate viruses reported here are known to potentially cause mortality events and/or disease in different seals, sea stars, fish, and bivalve species. Discussion: Canu performed better by producing the most viral contigs as compared to Metaflye with assemblies aligning to both protein and nucleotide databases. This study suggests that marine mammals can be used as important sentinels to surveil marine viruses that can potentially cause diseases in vertebrate and invertebrate hosts. [ABSTRACT FROM AUTHOR]

We report here changes in bird assemblages over a 14-year interval at the Port of Mar del Plata, Argentina, and the adjacent beach before (PRE) and after (POST) South American Sea Lions Otaria flavescens increased at a local haul-out. Abundance and number of bird species were compared between periods, between sites (beach, sea lion rookery, and port sheds), and between breeding and non-breeding seasons of the birds' annual cycle. A total of 13 116 birds belonging to 15 species were recorded. Total bird abundance was higher during the POST period compared to the PRE period, regardless of the season. Larids occurred in all sampled areas but with higher abundance at Punta Mogotes beach. The Kelp Gull Larus dominicanus, Brown-hooded and Grey-headed gulls Chroicocephalus spp., and the Snowy Sheathbill Chionis albus dominated assemblages during the PRE sea lion increase period, while Kelp Gulls, Brown-hooded Gulls, and the South American Tern Sterna hirundinacea dominated the POST period. Variation in the numbers of birds may be related to changes in feeding opportunity related to increased human activity (e.g., fishery wastes) as well as expansion of the local rookery of South American Sea Lions, another food source. [ABSTRACT FROM AUTHOR]

The influenza A virus (IAV) poses a significant global threat to public health and food security. Particularly concerning is the avian influenza virus (AIV) subtype H5N1, which has spread from Europe to North and Central/South America. This review presents recent developments in IAV evolution in birds, mammals, and humans in Chile. Chile's encounter with IAV began in 2002, with the highly pathogenic avian influenza (HPAI) H7N3 virus, derived from a unique South American low pathogenic avian influenza (LPAI) virus. In 2016–2017, LPAI H7N6 caused outbreaks in turkey, linked to wild birds in Chile and Bolivia. The pandemic influenza A (H1N1) 2009 (H1N1pdm09) virus in 2009 decreased egg production in turkeys. Since 2012, diverse IAV subtypes have emerged in backyard poultry and pigs. Reassortant AIVs, incorporating genes from both North and South American isolates, have been found in wild birds since 2007. Notably, from December 2022, HPAI H5N1 was detected in wild birds, sea lions, and a human, along Chile's north coast. It was introduced through Atlantic migratory flyways from North America. These findings emphasize the need for enhanced biosecurity on poultry farms and ongoing genomic surveillance to understand and manage AIVs in both wild and domestic bird populations in Chile. [ABSTRACT FROM AUTHOR]

To understand susceptibility of wild California sea lions and Northern elephant seals to influenza A virus (IAV), we developed an ex vivo respiratory explant model and used it to compare infection kinetics for multiple IAV subtypes. We first established the approach using explants from colonized rhesus macaques, a model for human IAV. Trachea, bronchi, and lungs from 11 California sea lions, 2 Northern elephant seals, and 10 rhesus macaques were inoculated within 24 h postmortem with 6 strains representing 4 IAV subtypes. Explants from the 3 species showed similar IAV infection kinetics, with peak viral titers 48 to 72 h post-inoculation that increased by 2 to 4 log10 PFU/explant relative to the inoculum. Immunohistochemistry localized IAV infection to apical epithelial cells. These results demonstrate that respiratory tissue explants from wild marine mammals support IAV infection. In the absence of the ability to perform experimental infections of marine mammals, this ex vivo culture of respiratory tissues mirrors the in vivo environment and serves as a tool to study IAV susceptibility, host range, and tissue tropism. IMPORTANCE Although influenza A virus can infect marine mammals, a dearth of marine mammal cell lines and ethical and logistical challenges prohibiting experimental infections of living marine mammals mean that little is known about IAV infection kinetics in these species. We circumvented these limitations by adapting a respiratory tract explant model first to establish the approach with rhesus macaques and then for use with explants from wild marine mammals euthanized for nonrespiratory medical conditions. We observed that multiple strains representing 4 IAV subtypes infected trachea, bronchi, and lungs of macaques and marine mammals with variable peak titers and kinetics. This ex vivo model can define infection dynamics for IAV in marine mammals. Further, use of explants from animals euthanized for other reasons reduces use of animals in research.

The "Special Issue of Technological Advances in the Study of Aquatic Mammals" in Aquatic Mammals journal showcases recent advancements in studying aquatic mammals. The issue covers various innovative methods such as AI, drones, genomics, and acoustic monitoring to understand marine mammal behavior, health, and ecology. Articles in the issue explore topics like using drones for monitoring dolphin welfare, assessing body condition in coastal dolphins, and counting manatees, offering valuable insights for researchers in the field. [Extracted from the article]

Repeated counts of animal abundance can reveal changes in local ecosystem health and inform conservation strategies. Unmanned aircraft systems (UAS), also known as drones, are commonly used to photograph animals in remote locations; however, counting animals in images is a laborious task. Crowd-sourcing can reduce the time required to conduct these censuses considerably, but must first be validated against expert counts to measure sources of error. Our objectives were to assess the accuracy and precision of citizen science counts and make recommendations for future citizen science projects. We uploaded drone imagery from Año Nuevo Island (California, USA) to a curated Zooniverse website that instructed citizen scientists to count seals and sea lions. Across 212 days, over 1,500 volunteers counted animals in 90,000 photographs. We quantified the error associated with several descriptive statistics to extract a single citizen science count per photograph from the 15 repeat counts and then compared the resulting citizen science counts to expert counts. Although proportional error was relatively low (9% for sea lions and 5% for seals during the breeding seasons) and improved with repeat sampling, the 12+ volunteers required to reduce error was prohibitively slow, taking on average 6 weeks to estimate animals from a single drone flight covering 25 acres, despite strong public outreach efforts. The single best algorithm was 'Median without the lowest two values', demonstrating that citizen scientists tended to under-estimate the number of animals present. Citizen scientists accurately counted adult seals, but accuracy was lower when sea lions were present during the summer and could be confused for seals. We underscore the importance of validation efforts and careful project design for researchers hoping to combine citizen science with imagery from drones, occupied aircraft, and/or remote cameras.

In recent years, there has been an increase in infectious diseases in marine mammals, including brucellosis, infections of morbillivirus, herpesvirus, and poxvirus. Several serological diagnostic methods, including enzyme-linked immunosorbent assays, immunofluorescence assays (ELISA), and western blotting, have been used to detect antibodies against pathogens in marine mammals. However, options for commercial secondary antibodies used to detect antibodies in marine mammals are limited; therefore, the use of proteins A, G, or chimeric protein AG may provide a suitable alternative. This study aimed to assess the use of proteins A, G, and chimeric protein AG to detect marine mammal immunoglobulins. Currently, there are no comparative studies on the use of proteins A, G, and chimeric protein AG for the detection of immunoglobulins in marine mammals. In this study, we used ten pinnipeds' species (Baikal seal, California sea lion, harbor seal, northern fur seal, ringed seal, South American fur seal, South American sea lion, spotted seal, Steller sea lion, and walrus) and five cetacean species (beluga whale, bottlenose dolphin, harbor porpoise, killer whale, and Pacific white-sided dolphin) and compare binding ability to proteins A, G, or chimeric protein AG by ELISA. The results revealed that the immunoglobulins from pinniped and cetacean species reacted more strongly to protein A than protein G. In addition, the immunoglobulins of pinnipeds and cetaceans showed a strong binding ability to chimeric protein AG. These results suggest that proteins A, G, and chimeric protein AG would be used to help further develop serological assays. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza (HPAI) A/H5N1 viruses (lineage 2.3.4.4b) are rapidly invading the Americas, threatening wildlife, poultry, and potentially evolving into the next global pandemic. In November 2022 HPAI arrived in Peru, triggering massive pelican and sea lion die-offs. We report genomic characterization of HPAI/H5N1 in five species of marine mammals and seabirds (dolphins, sea lions, sanderlings, pelicans and cormorants). Peruvian viruses belong to lineage 2.3.4.4b, but they are 4:4 reassortants where 4 genomic segments (PA, HA, NA and MP) position within the Eurasian lineage that initially entered North America from Eurasia, while the other 4 genomic segments (PB2, PB1, NP and NS) position within the American lineage (clade C) that circulated in North America. These viruses are rapidly accruing mutations, including mutations of concern, that warrant further examination and highlight an urgent need for active local surveillance to manage outbreaks and limit spillover into other species, including humans. Highly pathogenic avian influenza (HPAI) A/H5N1 has recently emerged in the Americas and has been implicated in mass die-off events of pelicans and sea lions. Here, the authors report sampling and characterisation of HPAI A/H5N1 genomes from five marine mammal and seabird species in Peru. [ABSTRACT FROM AUTHOR]

Age‐, region‐, and year‐specific estimates of reproduction are needed for monitoring wildlife populations during periods of ecosystem change. Population dynamics of Steller sea lions (Eumetopias jubatus) in Southeast Alaska varied regionally (with high population growth and survival in the north vs. the south) and annually (with reduced adult female survival observed following a severe marine heatwave event), but reproductive performance is currently unknown. We used mark‐resighting data from 1006 Steller sea lion females marked as pups at ~3 weeks of age from 1994 to 1995 and from 2001 to 2005 and resighted from 2002 to 2019 (to a maximum age of 25) to examine age‐, region‐, and year‐specific reproduction. In the north versus the south, age of first reproduction was earlier (beginning at age 4 vs. age 5, respectively) but annual birth probabilities of parous females were reduced by 0.05. In an average year pre‐heatwave, the proportion of females with pup at the end of the pupping season peaked at ages 12–13 with ~0.60/0.65 (north/south) with pup, ~0.30/0.25 with juvenile, and ~0.10 (both regions) without a dependent. In both regions, reproductive senescence was gradual after age 12: ~0.40, 0.40, and 0.20 of females were in these reproductive states, respectively, by age 20. Correcting for neonatal mortality, true birth probabilities at peak ages were 0.66/0.72 (north/south). No cost of reproduction on female survival was detected, but pup production remained lower (−0.06) after the heatwave event, which if sustained could result in population decline in the south. Reduced pup production and greater retention of juveniles during periods of poor prey conditions may be an important strategy for Steller sea lions in Southeast Alaska, where fine‐tuning reproduction based on nutritional status may improve the lifetime probability of producing pups under good conditions in a variable and less productive environment. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Killer whales (Orcinus orca), being the top predators in marine ecosystems. Topics include little direct evidence of sea otter consumption by killer whales, with only one consumption among the attacks; and predation was not considered to play a role in the decline.

Unmasked behavioral audiograms of two California sea lions (Zalophus californianus), an adult female (F01) and a subadult male (M02), were recorded using narrow-band frequency-modulated hearing test signals. Signals had a duration of 1 s and center frequencies ranging from 0.031 to 80 kHz. Hearing thresholds were measured by varying test signal amplitude according to the updown staircase method. The resulting underwater audiograms (50% detection thresholds) of the two sea lions were similar and showed the typical mammalian U-shape. Maximum hearing sensitivity (58 and 57 dB re 1 µPa) occurred at 11.3 kHz for F01 and at 8 kHz for M02, respectively. The range of best hearing (defined as < 10 dB from the maximum sensitivity) was from 1 to 16 kHz (four octaves). The detection thresholds for hearing test signal frequencies 0.031, 0.040, and 0.050 kHz were lower than expected, possibly caused by a shift in perceptional modality from auditory to vibrotactile, or due to the difficulty in measuring accurate SPLs of such low frequencies in a pool. Measurements of particle motion deemed detection of these very low frequencies via the vibrissae unlikely. The present study extends the frequency range for which the hearing of California sea lions has been tested. Based on the two audiograms of the present study and audiograms reported by Reichmuth et al. (2013) and Cunningham & Reichmuth (2016), a revised generic audiogram for California sea lions is proposed. [ABSTRACT FROM AUTHOR]