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While general enrichment strategies for captive animals attempt to elicit variable and species-typical behaviors, approaches to cognitive enrichment have been disappointingly one-size-fits-all. In this commentary, we address the potential benefit of tailoring cognitive enrichment to the cognitive niche of the species, with a particular focus on a reasonably well-studied marine carnivore, the sea lion. Sea lions likely share some cognitive evolutionary pressures with primates, including complex social behavior. Their foraging ecology, however, like that of many terrestrial carnivores, is based on the rapid and behaviorally flexible pursuit of avoidant prey. Unlike terrestrial carnivores, sea lions carry out this pursuit in a truly fluid three-dimensional field, computing and executing sensorimotor transformations from any solid angle to any other. The cognitive demands of flexible prey pursuit are unlikely to be fully elicited by typical stationary puzzle box style foraging enrichment devices or screen-based interactive games. With this species, we recommend exploring more water-based movement activities generally, and complex pursuit challenges specifically.

Marine heat waves (MHWs), extended periods of unusually high ocean temperatures that significantly impact marine ecosystems, are prevalent in the Southern California Bight (SCB), increased thermal stratification has intensified these events over recent decades, affecting California sea lions by disrupting prey availability, leading to malnutrition and higher mortality rates. Rising atmospheric CO2 levels have exacerbated this issue, contributing to the warming of surface waters. Climate models predict that MHWs will continue to increase in frequency, severity, and duration, posing further risks to marine life. Despite the presence of a significant sea lion colony off the coast of San Diego, little research has been conducted on MHWs in the SCB impact on the local sea lion population. This research examines various aspects of MHWs at San Diego, including defining MHWs, historical occurrences, current trends, and their implications for California sea lions, while exploring potential policy and mitigation strategies to protect Southern California's marine ecosystems. Daily sea Surface Temperature (SST) measurements from La Jolla Scripps Pier (1916-2023) are used to quantify local MHWs relative to a shifting baseline (i.e., one that adjusts for the long-term warming trend), and to a fixed baseline (i.e., the warming trend alone increases MHW occurrences). We investigate critical questions about MHW evolution and duration, considering the continuous warming of the oceans. We consider what the two definitions of MHWs imply for upwelling and nutrient supply to the ocean surface, and the implications for California sea lion prey availability. We identify future research priorities, particularly improved measures of sea lion population counts, and the need for better indicators of MHW impacts beyond SST.

Investigating anthropogenic acoustic disturbance and sound exposure in marine mammals requires evaluation of experimental approaches used to measure the sound levels experienced by the subjects. In previous research, exposure of California sea lions (Zalophus californianus) to eight narrow noise bands was estimated as the mean sound pressure level (SPL) measured by hydrophones placed at multiple locations and depths in a pool. We compare this method of SPL estimation with SPLs measured with a sound recording tag ("D-tag"). Measurements were taken from (1) hydrophones at locations on a grid; (2) a D-tag at the same locations; (3) a D-tag attached in its housing to a harness on a sea lion swimming freely in the pool; (4) a D-tag in its housing in one position in the pool; (5) a D-tag on the sea lion in one position in the pool; and (6) a D-tag turning in one location in the pool without its housing, in its housing, and on the sea lion while she rotated on her body axis. The SPLs recorded by the D-tag on a freeswimming sea lion were ~8 to 10 dB lower than those measured by the grid hydrophones, and the differences varied by frequency. These differences in SPL are caused by a combination of the directionality associated with the D-tag itself, the presence of the housing, acoustic effects of the sea lion's body, and periods that the D-tag was out of the water during respirations. Measuring mean sound levels in test pools using hydrophones deployed on grids is valid; however, attaching tags to wild marine mammals may be more feasible than using hydrophone grids at sea. We summarize considerations when selecting a method to fit the design of future research. [ABSTRACT FROM AUTHOR]

Pharmacokinetics studies have investigated meloxicam, a non‐steroidal anti‐inflammatory drug, dosing strategies in a wide variety of non‐domestic animals; however, there is no prior study examining well‐founded dosing for pinnipeds. To develop dosing protocols, pharmacokinetic information is needed, with an examination of differences between pinniped species. Apparently, healthy California sea lions (Zalophus californianus: CSL; n = 13) and Pacific harbor seals (Phoca vitulina richardii: PHS; n = 17) that had completed rehabilitation were enrolled into a population‐based pharmacokinetic study. Each animal was administered a single oral dose of meloxicam at 0.1 mg/kg, and two blood samples were collected from each animal at varying intervals during a 96‐h study period. Plasma concentrations of meloxicam were determined by high‐pressure liquid chromatography. Data were analyzed with nonlinear mixed effects modeling (Phoenix® NLME™, Certara, St. Louis, MO 63105, USA). The results indicated that in PHS, peak plasma concentration (Cmax) was 0.33 μg/mL with an elimination half‐life (Ke t½) of 31.53 h. In CSL, Cmax was 0.17 μg/mL with Ke t½ of 32.71 h. All animals enrolled completed the study without outward adverse clinical signs. The elimination half‐life was longer than previously recommended dosing intervals for pinnipeds; however, we cannot speculate in the optimum clinical dose from these results. [ABSTRACT FROM AUTHOR]

Orcas (Orcinus orca) are the top marine predators of the ocean, targeting multiple taxa including teleost fishes, elasmobranchs, seabirds, sea turtles, pinnipeds, odontocetes and other large cetaceans. According to their foraging strategies, genetics, acoustics, and morphology, orcas differentiate into ecotypes. Despite their cosmopolitan distribution, orcas are poorly studied in areas such as the Humboldt Current System of the Southeast Pacific coast. Since 2018 in northern Chile, presumed Type A orcas have been observed foraging on South American sea lions (Otaria byronia), benefiting from the presence of fishing vessels facilitating their hunt. These orcas were observed also pursuing large mixed groups of dusky (Lagenorhynchus obscurus) and long-beaked common dolphins (Delphinus capensis); however, predation on dusky dolphins was not documented. Here, we provide 28 additional sightings of orcas in two upwelling hotspots along northern Chile (15 around the Chañaral, Choros, and Damas Islandsin the Humboldt Penguin National Reserve from 2010-2023 and 13 in the Mejillones Peninsula from 2022-2023) and the first records of orcas effective hunting on dusky dolphins in this area. We present three new observations of orca tooth rake marks on fin whales (Balaenoptera physalus) dorsal fins in northern Chile. Furthermore, we observed the same orcas on two occasions foraging on dusky dolphins and sharing dolphin meat among group members. Overall, these observations suggest that orcas in northern Chile forage on marine mammals, especially on dusky dolphins, and the number of such predation events seems to be increasing near the coast. [ABSTRACT FROM AUTHOR]

Branched‐chain fatty acids (BCFAs) are mostly saturated fatty acids with a methyl branch at the penultimate or antepenultimate position to the CH3 end. Very‐long‐chain BCFAs (C ≥ 20) are uniquely found in surface lipids. Human and California sea lion (Zalophus californianus) are the only two species that possess vernix at birth, and vernix particles carry loads of BCFA to the gut, potentially influencing the establishment of the first microbiota. Horse (Equus caballus) contains high levels of BCFA in its surface lipids, and the current study aims to investigate if BCFA are components of a neonatal foal's gut. Electron ionization tandem mass spectrometry was used to distinguish iso‐ and anteiso‐form of BCFA from straight‐chain fatty acids. Abundant very‐long‐chain iso‐BCFA, mainly even‐numbered iso‐20:0, iso‐22:0, iso‐24:0, and iso‐26:0 were found in horse meconium but not in their manure collected a few months later. There are little differences in BCFA types and concentrations between foal manure and adult manure. Moderate to high levels of very‐long‐chain anteiso‐BCFA were also found. Comparisons of horse meconium BCFA to horse skin cholesterol ester BCFA content and to meconium from human and sea lion suggest its skin derived origin. The study expands our knowledge on the gut nutritional environment of a newborn horse, and further study is needed to establish the relationship between gut BCFA and microbiota composition in the first few hours of life. Practical Applications: Branched‐chain fatty acids (BCFA) are bioactive compounds found in vernix caseosa, the lipid‐laden material covering the surface of a newborn baby. BCFA also reaches high concentrations from the third trimester of gestation until birth. However, the exact functionality and mechanisms of BCFA in the surface and gut of a fetus remain unclear. The current study aims to clarify the lipid conditions in the gut of newborn foals and to identify the associations between BCFA in the gut and on the skin at a critical point when the horse's microbiota establishes itself. The findings of the current study lay a path for studying the physiological functions of BCFA in horse models, potentially accelerating research related to BCFA. [ABSTRACT FROM AUTHOR]

While researchers have made notable progress in bio-inspired swimming robot development, a persistent challenge lies in creating propulsive gaits tailored to these robotic systems. The California sea lion achieves its robust swimming abilities through a careful coordination of foreflippers and body segments. In this paper, reinforcement learning (RL) was used to develop a novel sea lion foreflipper gait for a bio-robotic swimmer using a numerically modelled computational representation of the robot. This model integration enabled reinforcement learning to develop desired swimming gaits in the challenging underwater domain. The novel RL gait outperformed the characteristic sea lion foreflipper gait in the simulated underwater domain. When applied to the real-world robot, the RL constructed novel gait performed as well as or better than the characteristic sea lion gait in many factors. This work shows the potential for using complimentary bio-robotic and numerical models with reinforcement learning to enable the development of effective gaits and maneuvers for underwater swimming vehicles. [ABSTRACT FROM AUTHOR]

This article discusses an observation of killer whales harassing humpback whales in offshore Brazilian waters. The observation took place in August 2023 and involved killer whales chasing and surrounding the humpback whales, with instances of physical contact. The behavior suggests that the killer whales may be targeting the humpback whales as prey. While fatal attacks are rare, there have been reports of such attacks in different regions of the world. The article also mentions that killer whales generally target smaller or younger whales during attacks. The observations provide new insights into the interactions between killer whales and humpback whales in the region, but it is unclear if these interactions have increased or are being recorded more frequently due to improved technology. This collection of scientific articles explores various aspects of killer whale interactions with other marine species in different regions, providing valuable insights into their behavior and ecological implications. These findings contribute to our understanding of the complex relationships between marine species and can inform conservation efforts. [Extracted from the article]

The distribution of New Zealand sea lions is typically localised to New Zealand and its remote subantarctic islands. However, non-resident male sea lions were seen on Macquarie Island, 650 km from their nearest natal islands, in all months of all years from 1965 to 1980. The majority of the apparently opportunistic sightings were at the northern end of the island. Sightings increased from May to a September-October peak that was coincident with the cessation of breeding activities in the sea lions' natal range and the period when resident gentoo and royal penguins, and fur and elephant seals aggregated for breeding, all of which are now confirmed prey for New Zealand sea lions on Macquarie Island. The long-term effect of predation pressure from New Zealand sea lions on resident species remains unmeasured. After sleeping, interacting with southern elephant seals was a core sea lion activity. Predation on seabirds and interactions with elephant seals increase the risk of cross-species disease transmission. [ABSTRACT FROM AUTHOR]

Summary: The base station receives the environmental data from a predetermined field that is collected and transferred by the sensors for processing and analysis. However, coverage maximization is the major issue that requires the deployment of varied sensor nodes (SNs), in such a way that optimizes network coverage while enduring practical limitations. This is pointed out to be a significant challenge in constructing WSNs. Since this is considered to be a well‐known NP‐hard issue, metaheuristic methods must be used for solving the realistic problem sizes. Hence, our work considers the problem of finding the best placement to ensure good network coverage in WSN. Accordingly, the solution to the above‐mentioned problem is modeled by covering a new 2‐D distance evaluation based on weighted Minkowski. Further, we deploy the Self Improved Sealion with Opposition Behavior (SI‐SLOB) algorithm for determining the optimal placement of given sensor nodes. In the end, we perform varied evaluations on distance and coverage area to ensure the enhancement of the SI‐SLOB scheme over the other state‐of‐the‐art algorithms. The proposed method achieves minimum distance mean value in target node 25, which is 4.1%, 4.0%, 2.3%, 5.1%, 3.5%, 3.0%, and 4.1% better than the other methods such as SLO, GWO, PSO, BMO, BOA, RHSO, and WOA, respectively. Thus the proposed WSN node coverage models have diverse applications across various domains, contributing to improved efficiency, safety, and resource management. [ABSTRACT FROM AUTHOR]

Across the world's oceans, our knowledge of the habitats on the seabed is limited. Increasingly, video/imagery data from remotely operated underwater vehicles (ROVs) and towed and drop cameras, deployed from vessels, are providing critical new information to map unexplored benthic (seabed) habitats. However, these vessel-based surveys involve considerable time and personnel, are costly, require favorable weather conditions, and are difficult to conduct in remote, offshore, and deep marine habitats, which makes mapping and surveying large areas of the benthos challenging. In this study, we present a novel and efficient method for mapping diverse benthic habitats on the continental shelf, using animal-borne video and movement data from a benthic predator, the Australian sea lion (Neophoca cinerea). Six benthic habitats (between 5-110m depth) were identified from data collected by eight Australian sea lions from two colonies in South Australia. These habitats were macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate reef and invertebrate boulder habitats. Percent cover of benthic habitats differed on the foraging paths of sea lions from both colonies. The distributions of these benthic habitats were combined with oceanographic data to build Random Forest models for predicting benthic habitats on the continental shelf. Random forest models performed well (validated models had a >98% accuracy), predicting large areas of macroalgae reef, bare sand, sponge/sand and invertebrate reef habitats on the continental shelf in southern Australia. Modelling of benthic habitats from animal-borne video data provides an effective approach for mapping extensive areas of the continental shelf. These data provide valuable new information on the seabed and complement traditional methods of mapping and surveying benthic habitats. Better understanding and preserving these habitats is crucial, amid increasing human impacts on benthic environments around the world. [ABSTRACT FROM AUTHOR]

Simple Summary: In this work, we documented the presence of two neurotrophins NGF (Nerve Growth Factor) and BDNF (Brain-Derived Neurotrophic Factor) in the pancreas of two species of marine mammals, Tursiops truncatus (common bottlenose dolphin) and Otaria flavescens (South American sea lion). Pancreas samples were provided by the Mediterranean Marine Mammal Tissue Bank of the Department of Comparative Biomedicine and Food Science of the University of Padua (Italy). These two growth factors are well-known mediators for maintaining the survival of neurons but also exert a metabotrophic effect. The localization in the pancreas of bottlenose dolphins and sea lions of these neurotrophins could help to better understand how these marine animals handle metabolic challenges in their adaptation to ocean life. In this study, we have investigated the immunolocalization of NGF (Nerve Growth Factor) and BDNF (Brain-Derived Neurotrophic Factor) in the pancreas of two species of marine mammals: Tursiops truncatus (common bottlenose dolphin), belonging to the order of the Artiodactyla, and Otaria flavescens (South American sea lion), belonging to the order of the Carnivora. Our results demonstrated a significant presence of NGF and BDNF in the pancreas of both species with a wide distribution pattern observed in the exocrine and endocrine components. We identified some differences that can be attributed to the different feeding habits of the two species, which possess a different morphological organization of the digestive system. Altogether, these preliminary observations open new perspectives on the function of neurotrophins and the adaptive mechanisms of marine mammals in the aquatic environment, suggesting potential parallels between the physiology of marine and terrestrial mammals. [ABSTRACT FROM AUTHOR]

Microgrid systems have emerged as a favourable solution for addressing the challenges associated with traditional centralized power grids, such as limited resilience, vulnerability to outages, and environmental concerns. As a consequence, this paper presents a hybrid renewable energy source (HRES)-based microgrid, incorporating photovoltaic (PV) system and wind to achieve sustainable and reliable power generation. A novel modified Z-source Zeta converter is incorporated in the system to enhance PV voltage together with hybridized grey wolf optimized sea lion algorithm-assisted PI controller for maintaining DC-link voltage. The wind system utilizes a doubly-fed induction generator (DFIG) for efficient power generation. To ensure effective functioning of DFIG, a proportional-integral (PI)-based droop control strategy is adopted, which regulates the power transfer from wind turbine to grid. In this proposed system, a bidirectional converter with a battery is utilized for energy storage and management. The battery can be charged and discharged in accordance with the needs of the system thanks to the bidirectional converter. Excess power generated by HRES systems is stored in the battery for later use during periods of low energy generation or high demand. Additionally, a dump load is included in the system to dissipate surplus power when battery is fully charged. MATLAB software is utilized validate the effectiveness and feasibility of proposed system, demonstrating improved power quality, grid integration, and energy management. [ABSTRACT FROM AUTHOR]

Clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 virus was detected in the South American sea lions found dead in Santa Catarina, Brazil, in October 2023. Whole genome sequencing and comparative phylogenetic analysis were conducted to investigate the origin, genetic diversity, and zoonotic potentials of the H5N1 viruses. The H5N1 viruses belonged to the genotype B3.2 of clade 2.3.4.4b H5N1 virus, which was identified in North America and disseminated to South America. They have acquired new amino acid substitutions related to mammalian host affinity. Our study provides insights into the genetic landscape of HPAI H5N1 viruses in Brazil, highlighting the continuous evolutionary processes contributing to their possible adaptation to mammalian hosts. [ABSTRACT FROM AUTHOR]

Sightings of pinnipeds in Colombian waters of the Pacific Ocean have sporadically been reported since 1970. Despite the Colombian Pacific region (CPR) not being within their typical distribution range, six pinniped species—the Galápagos fur seal (Arctocephalus galapagoensis), the Galápagos sea lion (Zalophus wollebaeki), the South American fur seal (Arctocephalus australis), the South American sea lion (Otaria byronia), the Juan Fernández fur seal (Arctocephalus philippii), and the southern elephant seal (Mirounga leonina)—have been recorded in recent times. This study presents an overall systematic review of pinniped sightings and strandings from 1970 to 2023 along the Pacific coast of Colombia, with a total of 68 sightings of 80 individuals. Pinnipeds were recorded most often in 1998 (13 individuals), followed by 2014 (nine individuals); 1997 (eight individuals); 1983 (seven individuals); and 1993, 1996, 2015, and 2020 (with three individuals each year). Most pinniped observations correspond to vagrants—solitary, young individuals sighted on the southern coast of the Colombian Pacific, specifically in Tumaco. Some records of these species appear to be influenced by upwelling events and changes in climatic-oceanographic phenomena (ENSO episodes) in the region. Further monitoring is necessary to determine whether species presence and abundance in the CPR is a response to (1) vagrant behavior of the species, (2) altered habitat use associated with bioecological changes in the species populations, and/or (3) shifts in distribution ranges related to potential new habitat suitability. [ABSTRACT FROM AUTHOR]

The California sea lion (Zalophus californianus) population in the Gulf of California has shown a significant abundance decline. However, its 13 breeding colonies have distinct individual dynamics modulated by regional environmental conditions. Thus, the relationship between environmental variability and population growth is complex and must be analyzed regionally. Los Islotes is the only colony that has steadily increased since the 1980s. The goal of this study was to determine the interannual changes in abundance and foraging habits (trophic breadth/habitat use) of adult females, and the interannual abundance and body mass of pups of the California sea lion colony from Los Islotes (Southwest Gulf of California) and its relationship with anomalous warming events. For this purpose, monthly population counts were carried out during the breeding seasons (2013–2018) and their interannual variability was analyzed. In addition, 152 pups were captured and weighted, and a small portion of hair was sampled to analyse the stable isotopes of nitrogen (δ15N) and carbon (δ13C) to obtain annual isotopic areas with the program R (SIBER routine). A 50–60% decrease in pups abundance was documented in warm years, such as 2014 and 2015, compared to 2013. Furthermore, pup body mass was negatively affected (by around 3 kg) during anomalous warming events in 2014 and 2018. The largest isotopic areas (3.18‰2 and 2.88‰2) were observed in 2016 and 2018, as a probable result of greater dispersion of adult females during their foraging trips. These results suggest adult females show adaptive responses to environmental variability. It is relevant to continue monitoring and understanding the dynamics of this colony, especially under current environmental change scenarios. [ABSTRACT FROM AUTHOR]

Pinnipeds (seals, sea lions, walruses, and their fossil relatives) are one of the most successful mammalian clades to live in the oceans. Despite a well-resolved molecular phylogeny and a global fossil record, a complete understanding of their macroevolutionary dynamics remains hampered by a lack of formal analyses that combine these 2 rich sources of information. We used a meta-analytic approach to infer the most densely sampled pinniped phylogeny to date (36 recent and 93 fossil taxa) and used phylogenetic paleobiological methods to study their diversification dynamics and biogeographic history. Pinnipeds mostly diversified at constant rates. Walruses, however, experienced rapid turnover in which extinction rates ultimately exceeded speciation rates from 12 to 6 Ma, possibly due to changing sea levels and/or competition with otariids (eared seals). Historical biogeographic analyses, including fossil data, allowed us to confidently identify the North Pacific and the North Atlantic (plus or minus Paratethys) as the ancestral ranges of Otarioidea (eared seals + walrus) and crown phocids (earless seals), respectively. Yet, despite the novel addition of stem pan-pinniped taxa, the region of origin for Pan-Pinnipedia remained ambiguous. These results suggest further avenues of study in pinnipeds and provide a framework for investigating other groups with substantial extinct and extant diversity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Humans have altered marine ecosystems over very long-time scales and historical data is often needed to understand the true magnitude of human impacts. The Southwest Atlantic Ocean has a long history of large-scale removal of marine vertebrates due to whaling, sealing, and fishing in the past three centuries. Historical catch records are crucial in assessing the conservation status of these historically over-exploited populations and setting suitable recovery goals. However, several gaps in the history of exploitation of many populations limit our ability to judge recoveries success. This study examines the history of the Spanish fishing company, the Real Compañía Marítima (Royal Maritime Company), and reconstructs its catches of marine mammals in Patagonia and on the north coast of the Río de la Plata. The analysis of a wide range of historical sources reveals that, between the years 1790 and 1804, the Company extracted less than 100 southern right whales Eubalaena australis, some 200,000 South American fur seals Arctocephalus australis and South American sea lions Otaria flavescens, and a few southern elephant seals Mirounga leonina. Although the Company's whale catch is negligible compared to that of other nations in the same whaling grounds, the amount of fur seals and sea lions removed from the ecosystem deserves attention. This historical survey provides us with the first estimate of the catches made by the Real Compañía Marítima. However, these figures only represent a small part of the extractive activities that took place in the region and further research is encouraged to assess the true dimension of human impacts on Southwest Atlantic ecosystems. The incorporation of retrospective data into ecological studies can be laborious and may have inherent biases, but it also provides valuable information for comprehending modern ecosystems and formulating appropriate conservation plans. [ABSTRACT FROM AUTHOR]

The northern coast of the San Jorge Gulf, Atlantic Patagonia, is recognised as a marine biodiversity hot spot and is designated as a priority conservation area. Among marine mammals, three species of pinnipeds inhabit the region. While South American sea lions (Otaria flavescens) have a higher abundance and a larger number of colonies than South American fur seals (Arctocephalus australis), a few individuals of the Southern elephant seal (Mirounga leonina) reside in the region. Nevertheless, little is known about the abundance and distribution of these pinnipeds before the 18th century, when various extractive activities became widespread, including the unregulated exploitation of furs and oil. This study aims to examine whether the distribution and relative abundance of ancient pinnipeds differ from present-day populations. To achieve this, we conducted inter-specific identification of pinniped bone remains coming from archaeological assemblages dated from 6000 to 600 14C years BP and reviewed historical sources to contrast these retrospective data with modern ecological literature. The results suggest changes over time in the relative abundances of species within the pinniped community. The relative abundance of fur seals was greater than or equal to that of sea lions in most Late-Holocene pinniped assemblages. Additionally, fur seals have been recorded in historical and Late-Holocene periods in places where they are currently very rare. These findings are consistent with the higher relative abundance of fur seals recorded in other archaeological sites along the Patagonian coast, suggesting that modern distribution and abundance have been heavily affected by commercial hunting. This study contributes to a better understanding of the nature and magnitude of the anthropic impact on the marine ecosystem of the northern coast of the San Jorge Gulf. It also provides historical baseline information to strengthen conservation policies and restoration efforts. [ABSTRACT FROM AUTHOR]

Anthropogenic debris is a global threat that impacts threatened species through various lethal and sub‐lethal consequences, as well as overall ecosystem health. This study used a database of over 24,000 beach surveys of marine debris collated by the Australian Marine Debris Initiative from 2012 to 2021, with two key objectives: (1) identify variables that most influence the occurrence of debris hotspots on a continental scale and (2) use these findings to identify likely hotspots of interaction between threatened species and marine debris. The number of particles found in each beach survey was modelled alongside fifteen biological, social, and physical spatial variables including land use, physical oceanography, population, rainfall, distance to waste facilities, ports, and mangroves to identify the significant drivers of debris deposition. The model of best fit for predicting debris particle abundance was calculated using a generalized additive model. Overall, debris was more abundant at sites near catchments with high annual rainfall (mm), intensive land use (km2), and that were nearer to ports (km) and mangroves (km). These results support previous studies which state that mangroves are a significant sink for marine debris, and that large ports and urbanized catchments are significant sources for marine debris. We illustrate the applicability of these models by quantifying significant overlap between debris hotspots and the distributions for four internationally listed threatened species that exhibit debris interactions; green turtle (26,868 km2), dugong (16,164 km2), Australian sea lion (2903 km2) and Flesh‐footed Shearwater (2413 km2). This equates to less than 1% (Flesh‐footed Shearwater, Australian sea lion), over 2% (green sea turtle) and over 5% (dugong) of their habitat being identified as areas of high risk for marine debris interactions. The results of this study hold practical value, informing decision‐making processes, managing debris pollution at continental scales, as well as identifying gaps in species monitoring. [ABSTRACT FROM AUTHOR]

Age determination of wild animals, including pinnipeds, is critical for accurate population assessment and management. For most pinnipeds, current age estimation methodologies utilize tooth or bone sectioning which makes antemortem estimations problematic. We leveraged recent advances in the development of epigenetic age estimators (epigenetic clocks) to develop highly accurate pinniped epigenetic clocks. For clock development, we applied the mammalian methylation array to profile 37,492 cytosine-guanine sites (CpGs) across highly conserved stretches of DNA in blood and skin samples (n = 171) from primarily three pinniped species representing the three phylogenetic families: Otariidae, Phocidae and Odobenidae. We built an elastic net model with Leave-One-Out-Cross Validation (LOOCV) and one with a Leave-One-Species-Out-Cross-Validation (LOSOCV). After identifying the top 30 CpGs, the LOOCV produced a highly correlated (r = 0.95) and accurate (median absolute error = 1.7 years) age estimation clock. The LOSOCV elastic net results indicated that blood and skin clock (r = 0.84) and blood (r = 0.88) pinniped clocks could predict age of animals from pinniped species not used for clock development to within 3.6 and 4.4 years, respectively. These epigenetic clocks provide an improved and relatively non-invasive tool to determine age in skin or blood samples from all pinniped species.

Body size and feeding morphology influence how animals partition themselves within communities. We tested the relationships among sex, body size, skull morphology and foraging in sympatric otariids (eared seals) from the eastern North Pacific Ocean, the most diverse otariid community in the world. We recorded skull measurements and stable carbon (δ13C) and nitrogen (δ15N) isotope values (proxies for foraging) from museum specimens in four sympatric species: California sea lions (Zalophus californianus), Steller sea lions (Eumetopias jubatus), northern fur seals (Callorhinus ursinus) and Guadalupe fur seals (Arctocephalus townsendi). Species and sexes had statistical differences in size, skull morphology and foraging significantly affecting the δ13C values. Sea lions had higher δ13C values than fur seals, and males of all species had higher values than females. The δ15N values were correlated with species and feeding morphology; individuals with stronger bite forces had higher δ15N values. We also found a significant community-wide correlation between skull length (indicator of body length), and foraging, with larger individuals having nearshore habitat preferences, and consuming higher trophic level prey than smaller individuals. Still, there was no consistent association between these traits at the intraspecific level, indicating that other factors might account for foraging variability.

Highly pathogenic influenza A virus (HPIAV) H5N1 within the genetic clade 2.3.4.4b has emerged in wild birds in different regions of the world, leading to the death of >70 million birds. When these strains spread to pinniped species a remarkable mortality has also been observed. A detailed genetic characterization of HPIAV isolated from pinnipeds is essential to understand the potential spread of these viruses to other mammalian species, including humans. To gain insight into these matters a detailed phylogenetic analysis of HPIAV H5N1 2.3.4.4b strains isolated from pinniped species was performed. The results of these studies revealed multiple transmission events from birds to pinnipeds in all world regions. Different evolutionary histories of different genes of HPIAV H5N1 2.3.4.4b strains gave rise to the viruses infecting pinnipeds in different regions of the world. European strains isolated from pinnipeds represent a completely different genetic lineage from strains isolated from South American ones. All strains isolated from pinnipeds bear characteristics of a highly pathogenic form for of avian influenza in poultry. Amino acid substitutions, previously shown to confer an adaptive advantage for infecting mammals, were observed in different genes in all pinniped species studied.

In human medicine, various pathologies, including decompression sickness, thrombocytopenia, and rheumatoid arthritis, have been linked to changes in cellular microparticles (MP) formation, particularly platelet microparticles (PMP). Similar disorders in marine mammals might be attributed to anthropogenic threats or illnesses, potentially impacting blood PMP levels. Thus, detecting platelet phosphatidylserine (PS) exposure and PMP formation could serve as a crucial diagnostic and monitoring approach for these conditions in marine mammals. Our group has developed a methodology to assess real-time PS exposure and PMP formation specifically tailored for marine mammals. This method, pioneered in species such as bottlenose dolphins, beluga whales, walruses, and California sea lions, represents a novel approach with significant implications for both clinical assessment and further research into platelet function in these animals. The adapted methodology for evaluating PS exposure and PMP formation in marine mammals has yielded promising results. By applying this approach, we have observed significant correlations between alterations in PMP levels and specific pathologies or environmental factors. These findings underscore the potential of platelet function assessment as a diagnostic and monitoring tool in marine mammal health. The successful adaptation and application of this methodology in marine mammals highlight its utility for understanding and managing health concerns in these animals. [ABSTRACT FROM AUTHOR]

The study of the immune function in marine mammals is essential to understand their physiology and can help to improve their welfare in the aquariums. Dedicating efforts to studying marine mammal physiology, pathophysiology, and implementing new diagnostic and therapeutic tools promote progress towards preventive medicine in aquariums by facilitating early detection and treatment of diseases. However, biological and clinical research on marine mammals is currently very limited due to difficult access to these species and their biological samples. With this objective, our group has adapted to marine mammals a commercially available assay routinely used to evaluate the phagocytic capacity of monocytes and granulocytes in human whole blood samples. We adapted IngoflowEx kit to bottlenose dolphins (Tursiops truncatus), beluga whales (Delphinapterus leucas), walruses (Odobenus rosmarus), Patagonian sea lions (Otaria flavescens), and harbor (Phoca vitulina). In this paper, we report the modifications carried out on the original protocol for their correct functioning in marine mammals. We obtained physiological values of phagocytic capacity in each species after repeated sampling for 4 years in various individuals of each species. Specific results revealed that the % phagocytic cells that ingested E.coli in bottlenose dolphins were 59.6 ± 1.27, in walruses 62.6 ± 2.17, in sea lions 57.5 ± 4.3, and in beluga whales 61.7 ± 1.4. In the case of the % phagocytic cells producing respiratory burst in bottlenose dolphins were 34.2 ± 3.6, in walruses 36.3 ± 4.3, in sea lions 40.8 ± 10.2, and in beluga whales 26.3 ± 3.7. These preliminary results can be used as a reference to detect alterations in phagocytic capacity either by immunosuppression or by exacerbation of the response in infectious inflammatory processes. Clinical applicability of the assay was verified in two clinical cases in which Ingoflow was useful to detect immune alterations in two diseased individuals, before and after the onset of clinical signs. [ABSTRACT FROM AUTHOR]

Simple Summary: Ultrasonography has been widely used in the field of veterinary medicine as a diagnostic tool for all kinds of animals, especially as a method of early diagnoses of pregnancy. Ultrasonography plays an important role in marine mammal preventative medicine and it is useful to monitor the estrus cycle, abnormal pregnancies, embryonic resorption, or fetal abortion. A large amount of studies is available on normal appearance during the fetal development in most domestic species; however, there is a lack of data to facilitate optimum diagnostic possibilities in marine mammals. This study provides additional information on maternal ultrasonographic monitoring and fetus wellness in California sea lion (Zalophus californianus) species, describing for the first time ultrasonographic findings from the ovulation up to the birth and the embryo and fetal organogenesis. Reproductive success is an important aspect of marine mammals' population health, as it is an indicator of the trajectory for the population into the future. The aim of this study is to provide additional relevant data on fetus–maternal ultrasonographic monitoring in sea lion species, in order to evaluate possible fetal distress or abnormalities. From 2018 to 2023, serial ultrasonographic scans of two healthy California sea lion females (16 ± 4 years old), kept under human care, were performed over the course of two pregnancies for each female. Animals were monitored from the ovulation to the delivery. Ultrasonography was performed weekly, and, during the last month, daily images were recorded using Logiq Versana Active, General Electric, with a 2–5 MHz curvilinear transducer, and Logiq V2, General Electric, with a 2–5 MHz curvilinear transducer. Right and left lateral recumbencies have been used during the examination. To the author's knowledge, this is the first study describing in detail the sea lion organogenesis and their correlation with the stage of pregnancy. [ABSTRACT FROM AUTHOR]

Simple Summary: The Steller sea lion (SSL) is the largest Otariidae family species widely distributed in the cold North Pacific Ocean. SSLs also migrate to Hokkaido, Japan, in the winter. SSLs travel south along the Sea of Japan coast for winter to catch the herring that spawn near the coast. SSLs utilize haulouts as rest sites during herring season, but this can be affected by weather- and human-related pressures. In this study, we investigated the haulout use patterns of SSLs and the effect of human disturbance over a period of three years. The behavior of the SSLs on the haulouts differed from when they were on rookeries. Furthermore, the number of SSLs on the haulout and the duration of time they spent there reduced from the first year (lower human pressure) to the third year (human presence increased). Based on these findings, the SSLs may adjust the timing of when they enter the water to around sunrise, following the ecology of the herring and to avoid human disturbance. Therefore, it is necessary to continue investigating the relationship between the ecology of the SSLs and environmental changes in order to determine the damage that the SSLs cause to fishery interests. Steller sea lions (SSLs) migrate to the Hokkaido coast to spend the winter there, leading to conflicts arising with fishermen over herring. This study analyzed the trends in the SSLs' use of a haulout as a rest site under human pressure. From January to March in 2017, 2018, and 2019, we recorded the SSL behavior at the haulout site off Otaru City, Hokkaido, for 24 h a day using a fixed-point video recorder. We investigated three years of data to analyze the relationships between the SSL behaviors (attendance/landing–entry timings/remaining on land) and herring caught. We also monitored the SSL behaviors during changes in weather conditions and under human pressure. Throughout the three years, the SSLs used the haulout site during harsher weather or under human pressure. In 2017 and 2018, there was a correlation between the herring caught and the maximum number of SSLs on the haulout, but not in 2019. The number of SSLs on the haulout increased from evening to night; most individuals entered the water in the morning. The SSLs probably return to the water around sunrise not only for foraging but also to avoid anthropogenic pressure. The damage caused to the herring fishery by the SSLs was severe, but it is also clear that human pressure changed their behavior in response. [ABSTRACT FROM AUTHOR]

The increased size and enhanced compliance of the aortic bulb—the enlargement of the ascending aorta—are believed to maintain blood flow in pinnipeds during extended periods of diastole induced by diving bradycardia. The aortic bulb has been described ex vivo in several species of pinnipeds, but in vivo measurements are needed to investigate the relationship between structure and function. We obtained ultrasound images using electrocardiogram‐gated transesophageal echocardiography during anesthesia and after atropine administration to assess the relationship between aortic bulb anatomy and cardiac function (heart rate, stroke volume, cardiac output) in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopias jubatus). We observed that the aortic bulb in northern fur seals and Steller sea lions expands during systole and recoils over the entire diastolic period indicating that blood flow is maintained throughout the entire cardiac cycle as expected. The stroke volumes we measured in the fur seals and sea lions fit the values predicted based on body size in mammals and did not change with increased heart rates, suggesting that greater stroke volumes are not needed for aortic bulb function. Overall, our results suggest that peripheral vasoconstriction during diving is sufficient to modulate the volume of blood in the aortic bulb to ensure that flow lasts over the entire diastolic period. These results indicate that the shift of blood into the aortic bulb of pinnipeds is a fundamental mechanism caused by vasoconstriction while diving, highlighting the importance of this unique anatomical adaptation. Research highlights: Aortic bulb expansion and recoil supported continuous blood flow in northern fur seals and Steller sea lions. Stroke volumes in these species matched predictions based on body size, suggesting that having a large aortic bulb does not necessitate having a greater stroke volume to support diving. [ABSTRACT FROM AUTHOR]

Background: Mammalian skeletons are largely formed before birth. Heterochronic changes in skeletal formation can be investigated by comparing the order of ossification for different elements of the skeleton. Due to the challenge of collecting prenatal specimens in viviparous taxa, opportunistically collected museum specimens provide the best material for studying prenatal skeletal development across many mammalian species. Previous studies have investigated ossification sequence in a range of mammalian species, but little is known about the pattern of bone formation in Carnivora. Carnivorans have diverse ecologies, diets, and biomechanical specializations and are well-suited for investigating questions in evolutionary biology. Currently, developmental data on carnivorans is largely limited to domesticated species. To expand available data on carnivoran skeletal development, we used micro-computed tomography (micro-CT) to non-invasively evaluate the degree of ossification in all prenatal carnivoran specimens housed in the Harvard Museum of Comparative Zoology. By coding the presence or absence of bones in each specimen, we constructed ossification sequences for each species. Parsimov-based genetic inference (PGi) was then used to identify heterochronic shifts between carnivoran lineages and reconstruct the ancestral ossification sequence of Carnivora. Results: We used micro-CT to study prenatal ossification sequence in six carnivora species: Eumetopias jubatus (Steller sea lion, n = 6), Herpestes javanicus (small Indian mongoose, n = 1), Panthera leo (lion, n = 1), Urocyon cinereoargenteus (gray fox, n = 1), Ursus arctos arctos (Eurasian brown bear, n = 1), and Viverricula indica (small Indian civet, n = 5). Due to the relatively later stage of collection for the available specimens, few heterochronic shifts were identified. Ossification sequences of feliform species showed complete agreement with the domestic cat. In caniforms, the bear and fox ossification sequences largely matched the dog, but numerous heterochronic shifts were identified in the sea lion. Conclusions: We use museum specimens to generate cranial and postcranial micro-CT data on six species split between the two major carnivoran clades: Caniformia and Feliformia. Our data suggest that the ossification sequence of domestic dogs and cats are likely good models for terrestrial caniforms and feliforms, respectively, but not pinnipeds. [ABSTRACT FROM AUTHOR]

A basin-scale Mediterranean carbonate system model has been setup, building on the POSEIDON operational biogeochemical model. The spatial variability of carbonate system variables from a 13-year simulation (2010-2022) was validated against CARIMED in situ data (DIC, TA, pCO2), showing reasonable agreement in reproducing the observed patterns and preserving the dynamics in different areas, except a slight overestimation (~15 µmol/kg) of TA in the Eastern Levantine. The time-variability of model outputs (DIC, TA, pCO2, pH) was validated, against available time-series from Western (DYFAMED, Villefranche-PointB) and Eastern Mediterranean (HCB) sites, showing good agreement with the data, particularly for pCO², pH and DIC. The model failed to reproduce the observed late summer peak of TA at DYFAMED/PointB sites, which may be partly attributed to the advection of lower alkalinity Atlantic water in the area. The seasonal variability of DIC and pCO2@20°C was found to be mainly controlled by winter mixing and the subsequent increase of primary production and net CO2 biological uptake, which appeared overestimated at HCB. Along with the reference simulation, three sensitivity simulations were performed, de-activating the effect of biology, evaporation and CO2 air-sea fluxes on DIC and TA, in order to gain insight on the processes regulating the simulated carbonate system variability. The effect of biological processes on DIC was found more significant (peak during spring) in the more productive North Western Mediterranean, while evaporation had a stronger impact (peak during late summer) in the Levantine basin. CO2 air-sea flux was higher in the Western Mediterranean, particularly the Gulf of Lions and Alboran Sea, as well as in river influenced areas, such as the N. Adriatic and along the pathway of the Black Sea Water in the Aegean. A weak release of CO2 was found in the Eastern Levantine and Libyan Sea. Its basin average (+2.1 mmol/m² / day) and positive trend (+0.1 mmol/m² /day/year) indicates a gradually increasing net CO2 ocean uptake. The simulated positive trends of DIC (0.77 mmol/kg/year) and TA (0.53 mmol/kg/year) in the North Western Mediterranean were consistent with observational and modelling studies, in constrast with the Levantine basin, where no significant trends were found for TA. [ABSTRACT FROM AUTHOR]

Sex identification is a common objective in molecular ecology. While many vertebrates display sexual dimorphism, determining the sex can be challenging in certain situations, such as species lacking clear sex-related phenotypic characteristics or in studies using non-invasive methods. In these cases, DNA analyses serve as valuable tools not only for sex determination but also for validating sex assignment based on phenotypic traits. In this study, we developed a bioinformatic framework for sex assignment using genomic data obtained through GBS, and having an available closely related genome assembled at the chromosome level. Our method consists of two ad hoc indexes that rely on the different properties of the mammalian heteromorphic sex chromosomes. For this purpose, we mapped RAD-seq loci to a reference genome and then obtained missingness and coverage depth values for the autosomes and X and Y chromosomes of each individual. Our methodology successfully determined the sex of 165 fur seals that had been phenotypically sexed in a previous study and 40 sea lions sampled in a non-invasive way. Additionally, we evaluated the accuracy of each index in sequences with varying average coverage depths, with Index Y proving greater reliability and robustness in assigning sex to individuals with low-depth coverage. We believe that the approach presented here can be extended to any animal taxa with known heteromorphic XY/ZW sex chromosome systems and that it can tolerate various qualities of GBS sequencing data. [ABSTRACT FROM AUTHOR]

Strategies to reduce the negative impacts of fisheries on ecosystems often come into conflict with fishers who have different experiences with, and perceptions of, biodiversity compared to policy makers and fisheries managers. We interviewed 800 fishers along 2400 kilometers of the Humboldt Current System (HCS) coast, assessing fishers' perceptions of the impacts of marine predators on fishing and their proposals to reduce conflicts with small-scale net fisheries. Vessel captains saw seabirds as positive indicators of fish presence along the HCS (mean probability 62.7%). In contrast, sea lions were perceived negatively, affecting catches for all fishers and causing fishing gear damage among gillnet fishers (97.1%). Among different measures suggested by fishers to reduce conflicts with non-target taxa, night fishing and marine protected areas (MPAs) were viewed as least likely to be implemented because these affect fishing performance (6% and 13.1%) through changes to at-sea safety and fishing effort displacement, respectively. In contrast, economic compensation and culling of currently protected sea lions were the most popular but also the most sensitive measures (31% and 33%, respectively). Different dimensions of experiences and perceptions of fishers are key to the bottom-up understanding of interactions in small-scale fisheries. This is especially true when measures to mitigate their impacts do not have any consolidated installation/monitoring, which is a continuing challenge for these types of fisheries globally. This study emphasizes the role of small-scale fishers as a source of diverse ecological experiences and perceptions to complement knowledge on sensitive conservation issues. [ABSTRACT FROM AUTHOR]

The article "Intraguild predation in pinnipeds: Southern sea lions prey upon adult female South American fur seals in the Falkland Islands" explores the phenomenon of intraguild predation among marine mammal carnivores, specifically pinnipeds. The authors argue that understanding intraguild predation in pinnipeds can provide insights into marine food webs. The study focuses on the predation behavior of southern sea lions on adult female South American fur seals in the Falkland Islands. The researchers observed risk-avoidant behavior in the fur seals and constructed a population model to assess the impact of sea lion predation on the fur seal population. The article suggests that changes in prey availability and increasing competition may contribute to the predation. [Extracted from the article]

Transient killer whales have been documented hunting marine mammals across a variety of habitats. However, relatively little has been reported about their predatory behaviours near deep submarine canyons and oceanic environments. We used a long-term database of sightings and encounters with these predators in and around the Monterey Submarine Canyon, California to describe foraging behaviour, diet, seasonal occurrence, and habitat use patterns. Transient killer whales belonging to the outer coast subpopulation were observed within the study area 261 times from 2006–2021. Occurrences, behaviours, and group sizes all varied seasonally, with more encounters occurring in the spring as grey whales migrated northward from their breeding and calving lagoons in Mexico (March-May). Groups of killer whales foraged exclusively in open water, with individuals within the groups following the contours of the submarine canyon as they searched for prey. Focal follows revealed that killer whales spent 51% of their time searching for prey (26% of their time along the shelf-break and upper slope of the canyon, and 25% in open water). The remainder of their time was spent pursuing prey (10%), feeding (23%), travelling (9%), socializing (6%), and resting (1%). Prey species during 87 observed predation events included California sea lions, grey whale calves, northern elephant seals, minke whales, common dolphins, Pacific white-sided dolphins, Dall's porpoise, harbour porpoise, harbour seals, and sea birds. The calculated kill rates (based on 270 hours of observing 50 predation events) were 0.26 California sea lions per killer whale over 24 hours, 0.11 grey whale calves, and 0.15 for all remaining prey species combined. These behavioural observations provide insights into predator-prey interactions among apex predators over submarine canyons and deep pelagic environments. [ABSTRACT FROM AUTHOR]

Changes in the behavior of free-living animals caused by natural and anthropogenic factors can influence their survival and reproduction. Tourist activities with sea lions in the wild have become an important attraction in various parts of the world. Although these animals appear to be habituated to human presence, in some cases, they have attacked humans, showing that they may be under a certain degree of stress. In this study, we analyzed California sea lions' maternal behavior under two contrasting scenarios of abundance and tourist activity in Los Islotes rookery, Mexico. We choose maternal behavior because it directly influences the pups' survival and the females' fecundity. The presence of tourist boats was not found to affect maternal behavior; however, behavior changes observed in the different scenarios were due to the number of females, the strong winds, and the increase in tide level due to the seasonality of the area. Although sea lions are apparently habituated to the presence of boats, it is recommended to continue monitoring the sea lion population and regulating tourism to be able to detect any change in the colony's population size and to rule out tourist activities as a possible cause. [ABSTRACT FROM AUTHOR]

Otariid gammaherpesvirus 1 (OtGHV1) is associated with high rates of urogenital carcinoma in free-ranging California sea lions (Zalophus californianus; CSL), and until recently was reported only in the Northern Hemisphere. The objective of this study was to survey free-ranging South American sea lions (Otaria byronia; SASL) and South American fur seals (Arctocephalus australis: SAFS) in Punta San Juan, Peru for OtGHV1 and to determine prevalence characteristics. Twenty-one percent (14/67) of urogenital swabs collected over three years (2011, 2014, 2015) from live pinnipeds of both species tested positive with a pan-herpesvirus conventional PCR. Sequencing of SAFS amplicons revealed 100% homology to OtGHV1 at the DNA polymerase, glycoprotein B, and viral bcl2-like genes. Sequencing of SASL amplicons revealed a novel related virus, herein called Otariid gammaherpesvirus 8 (OtGHV8). For comparison of sample sites, urogenital, conjunctival, and oropharyngeal swabs collected from 136 live pinnipeds of both species at Punta San Juan between 2011–2018 were then assayed using quantitative PCR for a segment of the OtGHV1/8 DNA polymerase gene using a qPCR assay now determined to cross-react between the two viruses. In total, across both species, 38.6% (51/132) of urogenital swabs, 5.6% (4/71) of conjunctival swabs, and 1.1% (1/90) of oropharyngeal swabs were positive for OtGHV1/8, with SASL only positive on urogenital swabs. Results from SASL were complicated by the finding of OtGHV8, necessitating further study to determine prevalence of OtGHV1 versus OtGHV8 using an alternate assay. Results from SAFS suggest a potential relationship between OtGHV1 in SAFS and CSL. Though necropsy surveillance in SAFS is very limited, geographic patterns of OtGHV1-associated urogenital carcinoma in CSL and the tendency of herpesviruses to cause more detrimental disease in aberrant hosts suggests that it is possible that SAFS may be the definitive host of OtGHV1, which gives further insight into the diversity and phyogeography of this clade of related gammaherpesviruses. [ABSTRACT FROM AUTHOR]

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]

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.