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Changing ratios of stable carbon (δ13C) and nitrogen (δ15N) isotopes in consumer tissues reflect foraging patterns over time and can be used to inform studies on historically vulnerable populations. Northern fur seals (NFS; Callorhinus ursinus) at San Miguel Island (SMI), California, have been severely impacted by climate events such as El Niño and remain susceptible to future environmental disturbances, necessitating the need to further understand their foraging ecology. We analyzed sequential δ13C and δ15N values along single NFS whiskers sampled from five pups and five unrelated post-parturient females at SMI and reconstructed temporally aligned stable isotope profiles for each whisker. Pup profiles consistently showed increases in postnatal δ13C and δ15N values that likely stem from pup consumption of maternal milk and changes in maternal foraging locations after parturition. Adult female profiles indicated predominantly heterogeneous foraging strategies and minimal foraging outside the Southern California Bight. These findings provide initial characterizations of longitudinal, stable isotope-derived foraging data for NFS from SMI and offer insight into the inference of otariid foraging ecology with sequential δ13C and δ15N values. [ABSTRACT FROM AUTHOR]

Free‐ranging otariids are routinely captured for data and sample collection. To achieve this, anesthesia may be used to facilitate handling, decrease stress, and improve human and animal safety. Injectable anesthetics are widely used for such endeavors; however, certain disadvantages to this approach warrant further exploration of alternative anesthetic techniques. Inhalant anesthesia, commonly utilized for otariids in a clinical setting, is used more sparingly in the field, with few studies assessing safety and efficacy in free‐ranging otariids. During 2016–2020, 175 Guadalupe fur seals were net‐captured and anesthetized with isoflurane and oxygen on Guadalupe Island, Mexico, for satellite telemetry attachment and biological sampling. To contribute to the body of knowledge surrounding the use of inhalants in the field, physiologic and anesthetic parameters (time to induction, total oxygen use, heart rate, respiratory rate, time to recovery, and anesthetic depth) were assessed for effects of biometric and logistical factors (pursuit and holding time, sex, age class, body weight, year, oxygen flow rate, and total anesthesia time). This anesthetic technique provided rapid induction and recovery times and rare side effects in Guadalupe fur seals, serving as a practical means of field immobilization for minimally invasive procedures in this imperiled species. [ABSTRACT FROM AUTHOR]

The use of acoustic signals to communicate is widespread among marine mammals and vocalizations are involved in all their social interactions. Due to many factors, acoustic features of a species' vocalizations may differ among populations. The present study investigated both micro‐ and macro‐geographical variation in the vocalizations of Cape fur seal females, males, and pups. Acoustic measurements were performed on calls recorded at four South African and two Namibian sites (maximum range ~ 1,000 km). Comparisons among close sites in South Africa revealed no micro‐geographical variation (maximum range ~130 km) in females' and pups' vocalizations. Barks of subadult males had different features among sites, which may be explained mostly by the context of call production. At the macro‐geographical scale (South Africa vs. Namibia), all call types varied significantly among sites. Several extrinsic and intrinsic factors were suggested to drive such differences. For females' and pups' calls, differences might be explained by environmental factors, whereas for males' barks, behavioral differences are the most likely explanation for acoustic differences (breeding vs. resting sites). Such investigations help understand how acoustic communication in marine mammals is shaped by ecological drivers. [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]

Background. The Galapagos sea lion, Zalophus wollebaeki, is an endemic and endangered otariid, which is considered as a sentinel species of ecosystem dynamics in the Galapagos archipelago. Mitochondrial DNA is an important tool in phylogenetic and population genetic inference. In this work we use Illumina sequencing to complement the mitogenomic resources for Zalophus genus-the other two species employed Sanger sequencing-by a complete mitochondrial genome and a molecular clock of this species, which is not present in any case. Materials and Methods. We used DNA obtained from a fresh scat sample of a Galapagos sea lion and shotgun-sequenced it on the Illumina NextSeq platform. The obtained raw reads were processed using the GetOrganelle software to filter the mitochondrial Zalophus DNA reads (~16% survive the filtration), assemble them, and set up a molecular clock. Results. From the obtained 3,511,116 raw reads, we were able to assemble a full mitogenome of a length of 16,676 bp, consisting of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNA), and two ribosomal RNAs (rRNA). A time-calibrated phylogeny confirmed the phylogenetic position of Z. wollebaeki in a clade with Z. californianus, and Z. japonicus, and sister to Z. californianus; as well as establishing the divergence time for Z. wollebaeki 0.65 million years ago. Our study illustrates the possibility of seamlessly sequencing full mitochondrial genomes from fresh scat samples of marine mammals. [ABSTRACT FROM AUTHOR]

The Australian fur seal (Arctocephalus pusillus doriferus, AUFS) population is still recovering from the over-exploitation of the commercial-sealing era (18th and 19th centuries). While the population is considered to be only < 47% of its pre-harvest size, it now represents the greatest resident marine predator biomass in the south-eastern Australian marine ecosystem. The region is experiencing rapid environmental change and, as a keystone predator species, the AUFS is an indicator of ecosystem health. In the present study, the body mass, standard length and body condition index (BCI) were analysed between 1997-2021 in adult female AUFS provisioning pups on Kanowna Island (northern Bass Strait), the third largest colony for the species. While substantial inter-annual fluctuations were observed, there was no temporal trend in standard length during the 23-year study period. In contrast, body mass and, consequently, BCI decreased significantly, suggesting the population is experiencing changing nutritional conditions. While these changes do not appear to be due to competition with commercial fisheries or population expansion, weak but significant negative relationships were observed between BCI and 1-year lagged sea surface temperature and summer zonal winds in the Bonney Upwelling region, and both current- and 2-year lagged Indian Ocean Dipole (IOD). These findings suggest the BCI of AUFS may continue to decline under predicted climate change conditions. While a lack of a concurrent decline in pup production could indicate a degree of nutritional tolerance or flexibility in energy allocation, further monitoring is required to assess decreases in reproductive parameters (e.g., birth mass, pre-weaning growth rates) or vital rates, which would be expected with continued nutritional stress.

Background The Galapagos sea lion, Zalophus wollebaeki, is an endemic and endangered otariid, which is considered as a sentinel species of ecosystem dynamics in the Galapagos archipelago. Mitochondrial DNA is an important tool in phylogenetic and population genetic inference. In this work we use Illumina sequencing to complement the mitogenomic resources for Zalophus genus—the other two species employed Sanger sequencing—by a complete mitochondrial genome and a molecular clock of this species, which is not present in any case. Materials and Methods We used DNA obtained from a fresh scat sample of a Galapagos sea lion and shotgun-sequenced it on the Illumina NextSeq platform. The obtained raw reads were processed using the GetOrganelle software to filter the mitochondrial Zalophus DNA reads (∼16% survive the filtration), assemble them, and set up a molecular clock. Results From the obtained 3,511,116 raw reads, we were able to assemble a full mitogenome of a length of 16,676 bp, consisting of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNA), and two ribosomal RNAs (rRNA). A time-calibrated phylogeny confirmed the phylogenetic position of Z. wollebaeki in a clade with Z. californianus, and Z. japonicus, and sister to Z. californianus; as well as establishing the divergence time for Z. wollebaeki 0.65 million years ago. Our study illustrates the possibility of seamlessly sequencing full mitochondrial genomes from fresh scat samples of marine mammals.

Abstract 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.

Quantifying metabolic rates and the factors that influence them is key to wildlife conservation efforts because anthropogenic activities and habitat alteration can disrupt energy balance, which is critical for reproduction and survival. We investigated the effect of diving behaviour, diet and season on field metabolic rates (FMR) and foraging success of lactating northern fur seals (Callorhinus ursinus) from the Pribilof Islands during a period of population decline. Variation in at-sea FMR was in part explained by season and trip duration, with values that ranged from 5.18 to 9.68 W kg-1 (n = 48). Fur seals experienced a 7.2% increase in at-sea FMR from summer to fall and a 1.9% decrease in at-sea FMR for each additional day spent at sea. There was no effect of foraging effort, dive depth or diet on at-sea FMR. Mass gains increased with trip duration and were greater in the fall compared with summer, but were unrelated to at-sea FMR, diving behaviour and diet. Seasonal increases in at-sea FMR may have been due to costs associated with the annual molt but did not appear to adversely impact the ability of females to gain mass on foraging trips. The overall high metabolic rates in conjunction with the lack of any diet-related effects on at-sea FMR suggests that northern fur seals may have reached a metabolic ceiling early in the population decline. This provides indirect evidence that food limitation may be contributing to the low pup growth rates observed in the Pribilof Islands, as a high metabolic overhead likely results in less available energy for lactation. The limited ability of female fur seals to cope with changes in prey availability through physiological mechanisms is particularly concerning given the recent and unprecedented environmental changes in the Bering Sea that are predicted to have ecosystem-level impacts.

Stable isotope analysis (SIA) of whiskers is increasingly used to investigate the foraging ecology of pinnipeds. An understanding of whisker growth dynamics is lacking for most species yet is necessary for study design and interpretation of isotope data. Here we present measurements of whisker growth obtained using photogrammetry in 5 California sea lions Zalophus californianus and 2 spotted seals Phoca largha. Data were collected from captive individuals for at least 1 yr, resulting in serial measurements of 321 sea lion and 153 spotted seal whiskers. The sea lion whiskers exhibited linear growth, with growth rates that ranged from

The highly dynamic nature of the marine environment can have a substantial influence on the foraging behaviour and spatial distribution of marine predators, particularly in pelagic marine systems. However, knowledge of the susceptibility of benthic marine predators to environmental variability is limited. This study investigated the influence of local-scale environmental conditions and large-scale climate indices on the spatial distribution and habitat use in the benthic foraging Australian fur seal (Arctocephalus pusillus doriferus; AUFS). Female AUFS provisioning pups were instrumented with GPS or ARGOS platform terminal transmitter tags during the austral winters of 2001–2019 at Kanowna Island, south-eastern Australia. Individuals were most susceptible to changes in the Southern Oscillation Index that measures the strength of the El Niño Southern Oscillation, with larger foraging ranges, greater distances travelled and more dispersed movement associated with 1-yr lagged La Niña-like conditions. Additionally, the total distance travelled was negatively correlated with the current year sea surface temperature and 1-yr lagged Indian Ocean Dipole, and positively correlated with 1-yr lagged chlorophyll-a concentration. These results suggest that environmental variation may influence the spatial distribution and availability of prey, even within benthic marine systems.

Detecting when and where animals feed is key to understanding their ecophysiology, but our ability to collect these data in marine mammals remains limited. Here, we test a tag-based accelerometry method to detect prey capture in California sea lions. From synchronized underwater video and acceleration data of two trained sea lions, we isolated a combined acceleration and Jerk pattern that reliably indicated prey capture in training datasets. We observed a stereotyped feeding motion in underwater video that included (1) mouth opening while approaching prey; (2) head deceleration to allow initial suction or prey engulfment, and (3) jaw closure. This motion (1–3) was repeated if a prey item was not initially engulfed. This stereotyped feeding motion informed a signal pattern phrase that accurately detected feeding in a training dataset. This phrase required (1) an initial heave-axis Jerk signal surpassing a threshold based on sampling rate; (2) an estimated dynamic surge-axis deceleration signal surpassing −0.7 g beginning within 0.2 s of the initial Jerk signal; and (3) an estimated dynamic surge-axis acceleration signal surpassing 1.0 g within 0.5 s of the beginning of the prior deceleration signal. We built an automated detector in MATLAB to identify and quantify these patterns. Blind tests of this detector on non-training datasets found high true-positive detection rates (91%–100%) with acceleration sampled at 50–333 Hz and low false-positive detection rates (0%–4.8%) at all sampling rates (16–333 Hz). At 32 Hz and below, true-positive detection rates decreased due to attenuation of signal detail. A detector optimized for an adult female was also accurate at 32–100 Hz when tested on an adult male's data, suggesting the potential future use of a generalized detector in wild subjects. When tested on the same data, a published triaxial Jerk method produced high true-positive detection rates (91–100%) and low-to-moderate false-positive detection rates (15–43%) at ≥ 32 Hz. Using our detector, larger prey elicited longer prey capture duration in both animals at almost all sampling rates 32 Hz or faster. We conclude that this method can accurately detect feeding and estimate relative prey length in California sea lions. [ABSTRACT FROM AUTHOR]

Management of gases during diving is not well understood across marine mammal species. Prior to diving, phocid (true) seals generally exhale, a behaviour thought to assist with the prevention of decompression sickness. Otariid seals (fur seals and sea lions) have a greater reliance on their lung oxygen stores, and inhale prior to diving. One otariid, the Antarctic fur seal (Arctocephalus gazella), then exhales during the final 50-85% of the return to the surface, which may prevent another gas management issue: shallow-water blackout. Here, we compare data collected from animalattached tags (video cameras, hydrophones and conductivity sensors) deployed on a suite of otariid seal species to examine the ubiquity of ascent exhalations for this group. We find evidence for ascent exhalations across four fur seal species, but that such exhalations are absent for three sea lion species. Fur seals and sea lions are no longer genetically separated into distinct subfamilies, but are morphologically distinguished by the thick underfur layer of fur seals. Together with their smaller size and energetic dives, we suggest their air-filled fur might underlie the need to perform these exhalations, although whether to reduce buoyancy and ascent speed, for the avoidance of shallow-water blackout or to prevent other cardiovascular management issues in their diving remains unclear. [ABSTRACT FROM AUTHOR]

Understanding the ecological and evolutionary processes that occur during range shift or (re‐)colonization is of critical importance for species whose ranges are changing due to human‐induced climate change or species such as New Zealand sea lions where their established colonies are significantly declining due to human impacts.The mechanisms underlying colonization are poorly understood. Observations are required to determine the processes that change individual's behaviour associated with colonization, but such observations are rare.Here, the establishment of a new breeding colony of New Zealand sea lions, Phocarctos hookeri, as they recolonized mainland New Zealand, an area from which they had been absent for ~200 years was investigated.There are differences in breeding location behaviour and population connectivity between established and establishing colonies of New Zealand sea lions. The recolonizing population is more dispersed with breeding locations that change annually and have more connections with other populations compared with established colonies and populations.The establishment of a new colony and the greater numbers of resightings between colonies means that for species' management, considerably more public education, habitat management, and protection is needed to ensure the safe return of New Zealand sea lions back on to mainland New Zealand. [ABSTRACT FROM AUTHOR]

Individual specialization in the foraging behaviour of marine predators can affect the ecology, evolution, and ability of a population to respond to environmental variability and human impacts.Here, blood serum and whisker stable isotope values from New Zealand (NZ) sea lion pups (Phocarctos hookeri) are compared with their mother's values to identify whether they can be used as proxies to identify their mother's isotopic niche and foraging strategy.Female NZ sea lions have been identified, both through telemetry and stable isotope research of blood serum and whiskers, to have two distinct foraging ecotypes (mesopelagic or benthic), consistent across their adult life. Females who are mesopelagic foragers have higher overlap and a greater risk of harmful interactions with fisheries.Stable isotope analysis of adult females can be used to determine the proportion of the female population exposed to these detrimental interactions. However, the capture, restraint, and removal of a whisker or blood from an adult female NZ sea lion is an expensive, time‐consuming, and invasive undertaking. Instead, by comparing the blood serum and whisker δ13C and δ15N values of 12 NZ sea lion mother‐and‐pup pairs, for whom the foraging behaviour of the female is known, the question as to whether a pup's blood serum or whisker isotope value can be used as a proxy to identify female foraging ecotype was investigated.The δ13C and δ15N values for the blood serum and whiskers of pups and their mothers were correlated and differed significantly between foraging ecotypes. This research validates that pup blood serum and whisker stable isotope values from 1‐month‐old pups can be used as indicators of female isotopic niche and therefore foraging ecotype.This tool can be used across all NZ sea lion colonies to indicate female NZ sea lion foraging ecotypes. For the Auckland Islands, it could determine the proportion of breeding females exposed to negative interactions with fisheries, leading to a better understanding of the level of these effects and helping to implement appropriate management to mitigate impacts. [ABSTRACT FROM AUTHOR]

Pinniped have evolved a range of reproductive and foraging patterns to deal with the constraint of terrestrial parturition and marine feeding. To understand the link between these constraints it is necessary to understand both reproductive periods on land and foraging at sea. I examined the foraging behavior of a phocid (northern elephant seal, Mirounga angustirostris) and otariid (California sea lion, Zalophus californianus) species to provide insight into the divergent life histories of these families. To understand foraging behavior it is necessary to know when and where animals find prey. Using stomach temperature telemetry, I conducted rigorous feeding experiments with both species to determine whether measures of stomach temperature can be used to identify and quantify prey consumption. Feedings were identified with high accuracy and the equations to estimate mass consumed were not significantly different between species.Until recently, studies on the foraging behavior of marine predators have relied on indirect measures of feeding, such as changes in diving behavior or movement patterns. When combined with measures of at sea behavior, stomach temperature telemetry can provide information about when and where animals uccessfully capture prey. I deployed stomach temperature telemeters along with time-depth recorders and satellite transmitters to examine the foraging behavior of northern elephant seals. This resulted in the first measures of feeding behavior and foraging success in elephant seals, as well as provided a validation of indirect indices of foraging behavior.Finally, I examined the foraging behavior of free-ranging California sea lions and documented how their behavior changed annually in response to environmental variation that occurred over three years. Although stomach temperature telemeters were deployed on sea lions, I was only able to maintain the telemeters in the animals for long enough to measure at sea feeding in one female. Therefore, foraging behavior was examined based on indirect measures of feeding, such as diving behavior and at sea distribution. I found females alter movement patterns in response to even modest environmental variation. Such detailed information on the foraging behavior of these species will make it possible to examine the link between reproductive pattern and at sea foraging behavior.

The energy expenditure of free-living fur seals and sea lions is difficult to measure directly, but may be indirectly derived from flipper stroke rate. We filmed 10 captive otariids swimming with accelerometers either attached to a harness (Daily Diary: sampling frequency 32 Hz, N=4) or taped to the fur (G6a+: 25 Hz, N=6). We used down sampling to derive four recording rates from each accelerometer (Daily Diary: 32, 16, 8, 4 Hz; G6a+: 25, 20, 10, 5 Hz). For each of these sampling frequencies, we derived 20 combinations of two parameters (RMW, the window size used to calculate the running mean; and m, the minimum number of points smaller than a local maxima used to detect a peak) from the dynamic acceleration of x, z and x+z, to estimate stroke rate from the accelerometers. These estimates differed by up to ∼20% in comparison to the actual number of foreflipper strokes counted from videos. RMW and the choice of axis used to make the calculations (x, z or x+z) had little effect on the overall differences, though the variability was reduced when using x+z. The best m varied depending on the axis used and the sampling frequency; a larger m was needed for higher sampling frequencies. This study demonstrates that when parameters are appropriately tuned, accelerometers are a simple yet valid tool for estimating the stroke rates of swimming otariids.

Background Accurate time-energy budgets summarise an animal’s energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of the energetic cost of that activity. Bio-loggers (e.g., accelerometers) may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips. Using low resolution to record behaviour may aid in the transmission of data, negating the need to recover the device. Methods This study used controlled captive experiments and previous energetic research to derive time-energy budgets of juvenile Australian fur seals (Arctocephalus pusillus) equipped with tri-axial accelerometers. First, captive fur seals and sea lions were equipped with accelerometers recording at high (20 Hz) and low (1 Hz) resolutions, and their behaviour recorded. Using this data, machine learning models were trained to recognise four states—foraging, grooming, travelling and resting. Next, the energetic cost of each behaviour, as a function of location (land or water), season and digestive state (pre- or post-prandial) was estimated. Then, diving and movement data were collected from nine wild juvenile fur seals wearing accelerometers recording at high- and low- resolutions. Models developed from captive seals were applied to accelerometry data from wild juvenile Australian fur seals and, finally, their time-energy budgets were reconstructed. Results Behaviour classification models built with low resolution (1 Hz) data correctly classified captive seal behaviours with very high accuracy (up to 90%) and recorded without interruption. Therefore, time-energy budgets of wild fur seals were constructed with these data. The reconstructed time-energy budgets revealed that juvenile fur seals expended the same amount of energy as adults of similar species. No significant differences in daily energy expenditure (DEE) were found across sex or season (winter or summer), but fur seals rested more when their energy expenditure was expected to be higher. Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving). Discussion As low resolution accelerometry (1 Hz) was able to classify behaviour with very high accuracy, future studies may be able to transmit more data at a lower rate, reducing the need for tag recovery. Reconstructed time-energy budgets demonstrated that juvenile fur seals appear to expend the same amount of energy as their adult counterparts. Through pairing estimates of energy expenditure with behaviour this study demonstrates the potential to understand how fur seals expend energy, and where and how behavioural compensations are made to retain constant energy expenditure over a short (dive) and long (season) period.

Background. Accurate time-energy budgets summarise an animal's energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of the energetic cost of that activity. Bio-loggers (e.g., accelerometers) may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips. Using low resolution to record behaviour may aid in the transmission of data, negating the need to recover the device. Methods. This study used controlled captive experiments and previous energetic research to derive time-energy budgets of juvenile Australian fur seals (Arctocephalus pusillus) equipped with tri-axial accelerometers. First, captive fur seals and sea lions were equipped with accelerometers recording at high (20 Hz) and low (1 Hz) resolutions, and their behaviour recorded. Using this data, machine learning models were trained to recognise four states--foraging, grooming, travelling and resting. Next, the energetic cost of each behaviour, as a function of location (land or water), season and digestive state (pre- or post-prandial) was estimated. Then, diving and movement data were collected from nine wild juvenile fur seals wearing accelerometers recording at high- and low- resolutions. Models developed from captive seals were applied to accelerometry data from wild juvenile Australian fur seals and, finally, their time-energy budgets were reconstructed. Results. Behaviour classification models built with low resolution (1 Hz) data correctly classified captive seal behaviours with very high accuracy (up to 90%) and recorded without interruption. Therefore, time-energy budgets of wild fur seals were constructed with these data. The reconstructed time-energy budgets revealed that juvenile fur seals expended the same amount of energy as adults of similar species. No significant differences in daily energy expenditure (DEE) were found across sex or season (winter or summer), but fur seals rested more when their energy expenditure was expected to be higher. Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving). Discussion. As low resolution accelerometry (1 Hz) was able to classify behaviour with very high accuracy, future studies may be able to transmit more data at a lower rate, reducing the need for tag recovery. Reconstructed time-energy budgets demonstrated that juvenile fur seals appear to expend the same amount of energy as their adult counterparts. Through pairing estimates of energy expenditure with behaviour this study demonstrates the potential to understand how fur seals expend energy, and where and how behavioural compensations are made to retain constant energy expenditure over a short (dive) and long (season) period. [ABSTRACT FROM AUTHOR]

Vocal characteristics can vary among and within populations. In species with geographic variation in the structure of vocalizations, individuals may have the ability to discriminate between calls from local and non-local individuals. The ability to distinguish differences in acoustic signals is likely to have a significant influence on the outcome of social interactions between individuals, including potentially mate selection and breeding success. Pinnipeds (seals, fur seals, sea lions and walruses) are highly vocal yet the Australian sea lion (Neophoca cinerea) is the only eared seal known to show geographic vocal variation in male barks. Barks are produced in many social interactions and encode sufficient information for both individual and colony identity to be discriminable. Yet until now, whether males could themselves discriminate these bark differences was unclear. We performed playback experiments in four breeding colonies to investigate whether males can discriminate local from non-local barks. Overall, males responded more strongly to barks from their own colony compared to barks from other colonies regardless of whether those other colonies were close or distant. Competition for females is high in Australian sea lions, but mating periods are asynchronous across colonies. The ability to correctly assess whether a male is from the same colony, thus representing a potential competitor for mates, or merely a visitor from elsewhere, may influence how males interact with others. Given the high cost of fighting, the ability to discern competitors may influence the nature of male–male interactions and ultimately influence how they allocate reproductive effort. [ABSTRACT FROM AUTHOR]

Understanding population size and trend is critical information in species management and conservation. To enable accurate population trend estimates, consistent robust monitoring of a species is essential, particularly for a species such as the New Zealand (NZ) sea lion, Phocarctos hookeri , which has experienced an almost continuous decline in pup production since the late 1990s., This research examines the pup production estimates for all known breeding sites for this species, and using a stage-structured matrix population model, estimates population size and trend between 1995 and 2015., Overall, it is estimated that 2,316 pups were born in 2015, a decrease of 13% since 1995 and a 27% decline since the highest pup production estimate in 1998. This decline has been driven by the significant decline of 48% at the main breeding area, the Auckland Islands since 1998., Using the stage-structured matrix population model a total species population size of 11,767 sea lions (95% CrI: 10,790-12,923) was estimated. This is the lowest population size of any sea lion species. Trend data for the Auckland Islands indicated that pup and population numbers have decreased at 1.9% yr−1 in the last 20 yr, while total species population decline is 0.6% yr−1., Estimates of population trends for this species have been hindered by inconsistent monitoring at most breeding sites. This study strengthens the growing field of research highlighting the need for consistent long-term monitoring for the conservation management of endangered species. [ABSTRACT FROM AUTHOR]

Physiology may limit the ability for marine mammals to adapt to changing environments. Depth and duration of foraging dives are a function of total available oxygen stores, which theoretically increase as animals grow, and metabolic costs. To evaluate how physiology may influence the travelling costs for seals to foraging patches in the wild, we measured metabolic rates of a cross-section of New Zealand fur seals, Australian fur seals and Australian sea lions representing different foraging strategies, development stages, sexes and sizes. We report values for standard metabolic rate, active metabolic rate (obtained from submerged swimming), along with estimates of cost of transport (COT), measured via respirometry. We found a decline in mass-specific metabolic rate with increased duration of submerged swimming. For most seals mass-specific metabolic rate increased with speed and for all seals mass-specific COT decreased with speed. Mass-specific metabolic rate was higher for subadult than adult fur seals and sea lions, corresponding to an overall higher minimum COT. Some sex differences were also apparent, such that female Australian fur seals and Australian sea lions had higher mass-specific metabolic rates than males. There were no species differences in standard or active metabolic rates for adult males or females. The seals in our study appear to operate at their physiological optimum during submerged swimming. However, the higher metabolic rates of young and female fur seals and sea lions may limit their scope for increasing foraging effort during times of resource limitation. [ABSTRACT FROM AUTHOR]

Diving is central to the foraging strategies of many marine mammals and seabirds. Still, the effect of dive depth on foraging cost remains elusive because energy expenditure is difficult to measure at fine temporal scales in wild animals. We used depth and acceleration data from eight lactating California sea lions (Zalophus californianus) to model body density and investigate the effect of dive depth and tissue density on rates of energy expenditure. We calculated body density in 5 s intervals from the rate of gliding descent. We modeled body density across depth in each dive, revealing high tissue densities and diving lung volumes (DLVs). DLV increased with dive depth in four individuals. We used the buoyancy calculated from dive-specific body-density models and drag calculated from swim speed to estimate metabolic power and cost of transport in 5 s intervals during descents and ascents. Deeper dives required greater mean power for round-trip vertical transit, especially in individuals with higher tissue density. These trends likely follow from increased mean swim speed and buoyant hinderance that increasingly outweighs buoyant aid in deeper dives. This suggests that deep diving is either a 'high-cost, high-reward' strategy or an energetically expensive option to access prey when prey in shallow waters are limited, and that poor body condition may increase the energetic costs of deep diving. These results add to our mechanistic understanding of how foraging strategy and body condition affect energy expenditure in wild breath-hold divers., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Weaning in mammals is typically thought of as the transition from reliance on maternal milk to feeding independently. Current theory suggests a complex process involving mothers imparting enough resources to offspring as to ensure survival without compromising both prior and future reproductive efforts, and the demands of offspring whose primary concern is survival. Otariid seals are a suitable group to study this given the morphological and behavioral similarities across species of the primary care giver, adult females. At higher latitudes, the duration of maternal care is short and tightly linked to seasonal productivity of the marine environment, punctuated by a predictable migration of mothers away from breeding sites. In contrast, nonmigratory temperate latitude otariid species have a much wider range of lactation periods, with mothers prolonging maternal support in relation to seasonal unpredictability of food resource. Prolonging care into the subsequent reproductive effort will likely have profound effects on the survival of the younger offspring. The Australian sea lion Neophoca cinerea has broken the phylogenetic constraint of a 12-month breeding cycle, which may reflect an alternate strategy to reduce the fitness costs of prolonged support by providing up to 18 months nutritional support to offspring. We use stable isotope analysis of temporally matched whisker sections combined with telemetry data on nutritionally dependent Australian sea lion pups to determine the weaning process and characterize the transition to nutritional independence. Using changes in isotopic nitrogen (δ15N) over time, pups undergo a gradual transition to independent foraging during a 3- to 6-month period before the onset of the next reproductive effort. Telemetry data supported this conclusion, indicating benthic foraging of weaned pups in areas consistent with adult female foraging. [ABSTRACT FROM AUTHOR]

Marine predator populations are sensitive to temporal variation in prey availability, but prey dynamics are often difficult to quantify. Long-term measures of offspring growth is a useful performance attribute to gauge the potential demographic direction for such predator populations, especially where other metrics (e.g., population size estimates) are lacking. Subantarctic fur seal (Arctocephalus tropicalis) females are central place foragers during a protracted lactation period, and their foraging success determines the growth and vitality of their offspring. Using data spanning over 2 decades, we assessed geographic and temporal variation in growth rates and weaning mass of subantarctic fur seal pups at 2 of the species' principal populations (Gough and Marion islands) and identified environmental conditions that may, through assumed bottom-up mechanisms, affect body mass at weaning. While Marion Island pups grew at an average rate of between 0.040 and 0.067 kg/day early in lactation (comparable to conspecific growth at Amsterdam Island), the mean growth rate at Gough Island (approximately 0.030 kg/day) was lower than the growth rate represented by the bottom 5% of the body mass distribution at Marion Island. Notwithstanding substantial interannual variability, we found support for a negative trend in weaning mass at both populations, suggesting a rise in limiting factors that is hypothesized to relate to concurrent local population size increases. Weaning mass tended to be higher when sea surface temperatures were warmer (with a stronger positive effect at Gough Island) and during positive phases of the Southern Oscillation Index (La Niña events), with a stronger positive effect in males. Given the low weaning mass of Gough Island fur seal pups, continued population growth here seems unlikely. While density-dependent regulation appears to have increased in strength at Marion Island, terminating rapid population growth, current weaning weights remain above the physiological limits of growth in subantarctic fur seals. [ABSTRACT FROM AUTHOR]

The Australian sea lion ( Neophoca cinerea ) experiences high pup mortality of seasonally alternating severity, partly attributed to endemic hookworm ( Uncinaria sanguinis ) infection. To further explore health outcomes of early hookworm elimination, a treatment trial was conducted at Seal Bay Conservation Park, South Australia, over consecutive lower and higher mortality breeding seasons (2019, 19.2%; 2020-1; 28.9%). Pups ( n = 322) were stratified into two age cohorts (median 14 d and 24 d recruitment ages) and randomly assigned to treated (topical ivermectin 500  μg/kg) or control (untreated) groups. A younger prepatent cohort <14 d old (median 10 d) was identified a posteriori . A seasonally independent growth benefit resulted from hookworm elimination across all age cohorts. The greatest relative improvements (bodyweight + 34.2%, standard length + 42.1%; p ≤ 0.001) occurred in the month post-treatment, in the youngest prepatent cohort. A significant benefit of lesser magnitude (bodyweight + 8.6-11.6%, standard length + 9.5-18.4%; p ≤ 0.033) persisted up to 3  months across all age cohorts - greatest in the youngest pups. Treatment resulted in immediate improvement in hematological measures of health - decreased anemia and inflammation severity ( p ≤ 0.012). These results enhance our understanding of host-parasite-environment interactions within the context of hematological ontogenesis, confirm the seasonally independent benefits of hookworm disease intervention, and further inform conservation recommendations for this endangered species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Lindsay, Fulham, Caraguel and Gray.)

Methods of calculating wildlife entanglement rates are not standardised between studies and often ignore the influence of observer effort, confounding comparisons. From 1997–2013 we identified 359 entangled Australian fur seals at Seal Rocks, south-eastern Australia. Most entanglement materials originated from commercial fisheries; most frequently entangling pups and juveniles. Using Generalized Additive Mixed Models, which incorporated observer effort and survey frequency, we identified that entanglements were observed more frequently amongst pups from July to October as they approached weaning. Neither the decline in regional fishing intensity nor changing seal population size influenced the incidence of entanglements. Using the models, we estimated that 302 (95% CI = 182–510) entangled seals were at Seal Rocks each year, equivalent to 1.0% (CI = 0.6–1.7%) of the site population. This study highlights the influence of observer effort and the value of long-term datasets for determining the drivers of marine debris entanglements. [ABSTRACT FROM AUTHOR]

The degree of individual specialization in resource use differs widely among wild populations where individuals range from fully generalized to highly specialized. This interindividual variation has profound implications in many ecological and evolutionary processes. A recent review proposed four main ecological causes of individual specialization: interspecific and intraspecific competition, ecological opportunity and predation., Using the isotopic signature of subsampled whiskers, we investigated to what degree three of these factors (interspecific and intraspecific competition and ecological opportunity) affect the population niche width and the level of individual foraging specialization in two fur seal species, the Antarctic and subantarctic fur seals ( Arctocephalus gazella and Arctocephalus tropicalis), over several years., Population niche width was greater when the two seal species bred in allopatry (low interspecific competition) than in sympatry or when seals bred in high-density stabilized colonies (high intraspecific competition). In agreement with the niche variation hypothesis ( NVH), higher population niche width was associated with higher interindividual niche variation. However, in contrast to the NVH, all Antarctic females increased their niche width during the interbreeding period when they had potential access to a wider diversity of foraging grounds and associated prey (high ecological opportunities), suggesting they all dispersed to a similar productive area., The degree of individual specialization varied among populations and within the annual cycle. Highest levels of interindividual variation were found in a context of lower interspecific or higher intraspecific competition. Contrasted results were found concerning the effect of ecological opportunity. Depending on seal species, females exhibited either a greater or lower degree of individual specialization during the interbreeding period, reflecting species-specific biological constraints during that period., These results suggest a significant impact of ecological interactions on the population niche width and degree of individual specialization. Such variation at the individual level may be an important factor in the species plasticity with significant consequences on how it may respond to environmental variability. [ABSTRACT FROM AUTHOR]

Vocalizing by males plays an important role in the reproductive activities of many species. Geographical variation in the characteristics of male vocalization is well studied in birds, but largely unexplored in mammals. This study quantified the extent of geographical variation in male Australian sea lion, Neophoca cinerea , barking calls and examined what drives vocal differences in this species. We recorded male barking calls from seven breeding colonies separated by ca. 5–2700 km enabling us to investigate acoustic differences on both micro- and macrogeographical scales. Our results revealed significant nonuniform geographical variation across colonies. Neither genetic nor geographical distances between colonies fully explained the observed acoustic variation. We suggest that environmental or morphological factors are likely to further contribute to differences in vocal characteristics. [ABSTRACT FROM AUTHOR]

Heart rate and peripheral blood flow distribution are the primary determinants of the rate and pattern of oxygen store utilisation and ultimately breath-hold duration in marine endotherms. Despite this, little is known about how otariids (sea lions and fur seals) regulate heart rate (fH) while diving. We investigated dive fH in five adult female California sea lions (Zalophus californianus) during foraging trips by instrumenting them with digital electrocardiogram (ECG) loggers and time depth recorders. In all dives, dive fH (number of beats/duration; 50±9 beats min-1) decreased compared with surface rates (113±5 beats min-1), with all dives exhibiting an instantaneous fH below resting (<54 beats min-1) at some point during the dive. Both dive fH and minimum instantaneous fH significantly decreased with increasing dive duration. Typical instantaneous fH profiles of deep dives (>100 m) consisted of: (1) an initial rapid decline in fH resulting in the lowest instantaneous fH of the dive at the end of descent, often below 10 beats min-1 in dives longer than 6 min in duration; (2) a slight increase in fH to ~10-40 beats min-1 during the bottom portion of the dive; and (3) a gradual increase in fH during ascent with a rapid increase prior to surfacing. Thus, fH regulation in deep-diving sea lions is not simply a progressive bradycardia. Extreme bradycardia and the presumed associated reductions in pulmonary and peripheral blood flow during late descent of deep dives should (a) contribute to preservation of the lung oxygen store, (b) increase dependence of muscle on the myoglobin-bound oxygen store, (c) conserve the blood oxygen store and (d) help limit the absorption of nitrogen at depth. This fH profile during deep dives of sea lions may be characteristic of deep-diving marine endotherms that dive on inspiration as similar fH profiles have been recently documented in the emperor penguin, another deep diver that dives on inspiration. [ABSTRACT FROM AUTHOR]

The diving capacity of marine mammals is typically defined by the aerobic dive limit (ADL) which, in lieu of direct measurements, can be calculated (cADL) from total body oxygen stores (TBO) and diving metabolic rate (DMR). To estimate cADL, we measured blood oxygen stores, and combined this with diving oxygen consumption rates (VO) recorded from 4 trained Steller sea lions diving in the open ocean to depths of 10 or 40 m. We also examined the effect of diving exercise on O stores by comparing blood O stores of our diving animals to non-diving individuals at an aquarium. Mass-specific blood volume of the non-diving individuals was higher in the winter than in summer, but there was no overall difference in blood O stores between the diving and non-diving groups. Estimated TBO (35.9 ml O kg) was slightly lower than previously reported for Steller sea lions and other Otariids. Calculated ADL was 3.0 min (based on an average DMR of 2.24 L O min) and was significantly shorter than the average 4.4 min dives our study animals performed when making single long dives-but was similar to the times recorded during diving bouts (a series of 4 dives followed by a recovery period on the surface), as well as the dive times of wild animals. Our study is the first to estimate cADL based on direct measures of VO and blood oxygen stores for an Otariid and indicates they have a much shorter ADL than previously thought. [ABSTRACT FROM AUTHOR]

A time series of aerial censuses of Cape fur seal colonies, spanning four decades (1972-2009) and three countries (South Africa, Namibia, and Angola), was analyzed to assess spatio -temporal changes in population numbers. A weighted quantile regression approach was used to estimate trends in pup counts that were used as proxies for numbers of older animals at breeding colonies. There was a 74% increase in the number of breeding colonies over the study period, from 23 in 1973 to 40 in 2009. There was also a significant northward shift in the distribution of the breeding population. This was largely attributable to events in the northern part of the population's range coinciding with Namibia, where seal numbers declined at most colonies in the south of Namibia while several new breeding colonies developed in the northern part of Namibia and one in southern Angola. Despite range expansion and the development of new colonies, the overall size of the population in 2009 was similar to that of the early 1990s, according to the pup count models. Potential mechanisms for the observed changes, and their management implications, are discussed. [ABSTRACT FROM AUTHOR]

The article discusses the first study to present data on the morphology and sex ratio for dead Australian sea lion Neophoca cinerea pups, conducting gross necropsies on all dead pups at Seal Bay Conservation Park for the examination of the inferred predominant cause of death. The study found no sex bias in the dead pups or in each classification of cause of death. The cause of death could not be inferred from gross necropsy in 49 percent of mortalities. In instances where the cause of death was inferred, it revealed that 31.6 percent were due to trauma inflicted by conspecific aggression in both males and females, followed by emaciation at 10.4 percent, and stillbirth or premature birth at 7.6 percent.

A bstract The Australian sea lion ( Neophoca cinerea) population at Seal Bay Conservation Park, South Australia, is estimated to be declining at a rate of 1.14% per breeding season. To better understand the potential causes of this decline, survival rates were examined to 14 yr of age for eight cohorts marked as pups (aged 0.17 yr) between 1991 and 2002. Apparent yearly survival rates (Φ) varied by cohort for pups from marking to weaning at 1.5 yr (Φ= 0.30-0.67). Postweaning juvenile survival (1.5-3 yr) was 0.89 and survival from 3 to 14 yr was constant (Φ female:male = 0.96:0.89). Φ of pup cohorts was negatively correlated to local sea surface temperature where the sea lions forage (SST) and was especially low for cohort 7 in 2000 (0.30). It is possible that periods of unusually warm oceanographic conditions may be limiting primary production and inhibiting maternal provisioning to pups. Pup survival to weaning is relatively low compared to other otariid species, is likely to limit recruitment, and may be contributing to the decline in pup abundance observed in the colony. [ABSTRACT FROM AUTHOR]

The Australian sea lion, Neophoca cinerea, one of the world’s rarest otariids, is notable for an asynchronous, aseasonal breeding chronology. Determining the ecological features that shape the genetic structure of marine predators such as Australian sea lions is challenging because their demersal foraging habitat is difficult to observe and quantify. Recent developments in stable isotope screening techniques using milk-dependent pups as proxies for maternal isotope signatures identified temporally stable, alternative (inshore and offshore) foraging ecotypes in adult female Australian sea lions. We combined this technique with mitochondrial DNA (mtDNA) analysis of samples of 40–60% of all pups produced at 17 of the largest South Australian colonies to determine whether ecological specialization in foraging ecotype within and between colonies has shaped maternal population structure within the species. Genetic isolation by distance was apparent at very fine geographical scales with three distinct clusters of colonies that share multiple haplotypes being interspersed with isolated breeding sites. There was no congruence between mtDNA haplotype distribution and foraging ecotypes suggesting that observed behavioural specialization was not maintained along matrilines. We propose that foraging specialization within discrete fine-scale foraging areas and habitats at the individual level limits the dispersive capacity of adult female Australian sea lions which in turn drives population structure. Given this species’ vulnerability to anthropogenic impacts and the high degree of female population structure, determining the extent of male-mediated gene flow in this species is critical. Only then can breeding colony connectivity be established and appropriate management units identified for the species. [Copyright &y& Elsevier]

Abstract: Genetic analyses can reliably determine the relationships among putative cases of twins in pinniped species. These studies demonstrate that field observations of nursing twins may often be cases of adoption or foster nursing of unrelated pups. A recent study of Antarctic fur seals (Arctocephalus gazella) on South Georgia Island found that only 3 of 11 putative twin cases were truly twins. Here we report results of genetic testing of eight putative cases of twinning (twin siblings and mother) observed at Cape Shirreff (62°27′30″S, 60°47′17″W), Livingston Island, Antarctica. Parentage and relatedness analyses using 18 microsatellite markers confirmed six out of the eight cases as twins and two cases of adoption/foster nursing of unrelated pups. All twins analyzed were dizygotic and in five out of six cases, the twins were likely full siblings (relatedness coefficient, or r xy μ=0.46, σ2 =0.004). In one case, the twins were likely half-siblings (r xy =0.17), supporting a previous finding of heteropaternity in Antarctic fur seals. This result suggests that mate infidelity during estrus maybe common in Antarctic fur seals, which has implications for our understanding of this species''s mating system. The twinning rate estimated at Cape Shirreff (0.12% or 6 twins per 4,965 births) is consistent with the scarcity of twin births observed in pinnipeds, which is associated with the high cost of nursing multiple pups in these animals. [Copyright &y& Elsevier]

The article discusses a study aimed at establishing the temporal fidelity of previously detected alternate foraging behaviours of adult female Australian sea lions and determining whether individual foraging specialisation led to significantly different phenotypes using proximal metrics of movement, diving and morphology. Whisker samples, depths and location data were gathered from 20 adult female Australian sea lions at 7 breeding colonies across the South Australian range. It suggests that long-term individual specialisation can confound population level generalisations and that the synergistic use of biogeochemical markers and tracking data is a powerful, cost-effect tool to determine the spatial and temporal utilisation of foraging habitat.

Stable carbon (δ 13C) and nitrogen (δ 15N) isotopes are used frequently to describe the trophic ecology of top marine mammal predators. Australian sea lions (Neophoca cinerea) are one of the world’s rarest otariid seals and exhibit the highest levels of natal site philopatry of any seal. We report the development of a screening technique to identify different foraging ecotypes and assess their relative frequencies inAustralian sea lionbreeding colonies using stable isotope ratios in pups. Geospatial and dive data from 15 adult females at three breeding colonies revealed alternate foraging strategies (inshore and offshore foraging) that were reflected in significant changes in δ13 C and δ15 N. Isotope fractionation from mother to pup was validated using paired whisker and blood serum samples with no significant difference between δ13 C and δ15 N enrichment of +1.27‰(whiskers) and +1.92‰(blood serum) from mothers to pups. Isotope ratios from whisker samples representing over 50% of pups born at threecolonies revealed significant intercolony differences in maternal foraging ecotype frequencies. These results are unique in that ecologicalpartitioning over such a small spatial scale has not been described in any other otariid species. [ABSTRACT FROM AUTHOR]

Abstract: The hormonal factors that influence development from birth to weaning in otariid seals is still largely unknown. In the present study, a suite of thyroid hormones and cortisol were measured in Australian fur seal pups in order to determine baseline concentrations as well as to describe their endocrinology over this critical developmental period. A cross-section of newborn pups from a breeding colony located on Kanowna Island, Australia were sampled at six different times over the course of the 10month lactation period. Sample times were designed to correspond to periods of heightened physiological change during pre-weaning development: post-natal, pre-molt, the initiation of molt, mid-molt, period of peak milk intake and weaning. Results indicate that the greatest hormonal changes were associated with the post-natal stage and molt, with molt showing the greatest changes, as has been reported for several species of pinnipeds. Two forms of thyroid hormones analyzed (Total T4, and Free T3), increased with the initiation of the molt, and Free T3 exhibited a second increase that was associated with the period of peak milk intake. The T3:T4 ratio was significantly lower during the initiation of molt than either pre- or mid-molt. The study was able to describe physiological change during the first year of life in Australian fur seals as well as document basal concentrations of thyroid hormones and cortisol in pups of this species. [Copyright &y& Elsevier]

Abstract: Five novel DNA-dependent DNA polymerase (Dpol) herpesviral sequences were generated using nested consensus polymerase chain reaction (PCR) in clinical samples from a harbor seal (Phoca vitulina), bottlenose dolphin (Tursiops truncatus), orca (Orcinus orca), California sea lion (Zalophus californianus), and a Phocid herpesvirus 2 (PhHV-2) isolate from a harbor seal (used as positive control). These novel sequences and other representative herpesvirus sequences were included in Bayesian and Maximum Likelihood analyses to illustrate the phylogeny of herpesviruses amongst the marine mammal host species and in comparison to those of other animals. All 19 novel and known marine mammal herpesviruses included in the analyses aligned with members of the Alphaherpesvirinae or Gammaherpesvirinae subfamilies. The novel harbor seal herpesvirus clustered with members of the Macavirus genus, subfamily Gammaherpesvirinae. The novel bottlenose dolphin herpesvirus clustered together in a monophyletic group with another delphinid alphaherpesvirus but could not be associated with an established genus. The orca herpesvirus also clustered with a delphinid alphaherpesvirus and formed a separate clade. The sea lion herpesvirus clustered with PhHV-2. PhHV-1 clustered with varicelloviruses and PhHV-2 clustered strongly in the Gammaherpesvirinae genus Percavirus. All cetacean gammaherpesviruses formed a monophyletic clade and could not be associated with an established gammaherpesviral genus. [Copyright &y& Elsevier]

Endothermic mammals in cold environments have a range of adaptations enabling them to maintain a constant core body temperature. Of critical importance to many is a thick hair coat that retains air and so acts as a barrier to minimize heat exchange between the skin and ambient environment. Disruption to the pelage can increase costs of maintaining body temperature and compromise survival of the individual. Fur seals rely on a pelage of dense, dry underfur protected by guard hairs for insulation in the aquatic environment. Since 1989 a potentially serious alopecia (hair loss) syndrome has been recognized in Australian fur seals. Between September 2007 and February 2010 we investigated the prevalence and potential impacts of the condition. The syndrome manifests as bilaterally symmetrical alopecia, which occurs predominantly in juveniles and has a strong sex bias (51 of 55 juveniles captured for examination were female). It also occurs in adult females but has never been seen on postpubescent males. Prevalence of alopecia was highest at the large Lady Julia Percy Island colony (approximately 30,000 seals) in northwestern Bass Strait where it has a distinct seasonal pattern of prevalence, peaking in spring and summer with up to 50% of juvenile females affected. Thermal images indicated that alopecic and nonalopecic areas of the dorsal thorax had a mean difference of 6.6°C, and affected animals were in significantly (P < 0.001) poorer body condition than unaffected animals. [ABSTRACT FROM AUTHOR]