Harbor Seals

SUMMARY This study investigated physiological and behavioural aspects of diving development in pups of the harbour seal Phoca vitulina. Behavioural data (4280 h, 6027 dives) from time/depth recorders (N=13) deployed on pups aged 0–19 days are presented concomitantly with physiological measurements (N=8, sampled both early and late in the nursing period) of blood oxygen stores and body composition. Pups grew from 12.6±1.8 kg (mean age 2 days, total body fat 16±4 %) to 22.2±2.5 kg (mean age 16 days, total body fat 35±5 %; means ± s.d.) over the duration of the experiment. Pups less than 5 days of age had an elevated haematocrit and reduced plasma volume compared with older pups. Although plasma volume and blood volume increased, mass-specific blood oxygen stores (total haemoglobin) fell during the study period. Simultaneously, the following behavioural indicators of diving ability increased: the proportion of time spent in the water, dive depth, dive duration, bottom time and maximum ...

Sea lion and seal populations in Alaskan waters underwent various degrees of decline during the latter half of the twentieth century and the cause(s) for the declines remain uncertain. The stable carbon ( 13 C/ 12 C) and nitrogen ( 15 N/ 14 N) isotope ratios in bone collagen from wild Steller sea lions (Eumetopias jubatus), northern fur seals (Callorhinus ursinus) and harbor seals (Phoca vitulina) from the Bering Sea and Gulf of Alaska were measured for the period 1951-1997 to test the hypothesis that a change in trophic level may have occurred during this interval and contributed to the population declines. A significant change in δ 15 N in pinniped tissues over time would imply a marked change in trophic level. No significant change in bone collagen δ 15 N was found for any of the three species during the past 47 years in either the Bering Sea or the Gulf of Alaska. However, the 15 N in the Steller sea lion collagen was significantly higher than both northern fur seals and harbor seals. A significant decline in δ 13 C (almost 2 ‰ over the 47 years) was evident in Steller sea lions, while a declining trend, though not significant, was evident in harbor seals and northern fur seals. Changes in foraging location, in combination with a trophic shift, may offer one possible explanation. Nevertheless, a decrease in δ 13 C over time with no accompanying change in δ 15 N suggests an environmental change affecting the base of the foodweb rather than a trophic level change due to prey switching. A decline in the seasonal primary production in the region, possibly resulting from decreased phytoplankton growth rates, would exhibit itself as a decline in δ 13 C. Declining production could be an indication of a reduced carrying capacity in the North Pacific Ocean. Sufficient quantities of optimal prey species may have fallen below threshold sustaining densities for these pinnipeds, particularly for yearlings and subadults who have not yet developed adequate foraging skills.

Obtaining population estimates of species that are not easily observed directly can be problematic. However, central place foragers can often be observed some of the time, e.g. when seals are hauled out. In these instances, population estimates can be derived from counts, combined with information on the proportion of time that animals can be observed. We present a modelling framework to estimate seasonal absolute abundance using counts and information from satellite telemetry data. The method was tested on a harbour seal population in an area of southeast Scotland. Counts were made monthly, between November 2001 and June 2003, when seals were hauled out on land and were corrected for the proportion of time the seals were at sea using satellite telemetry. Harbour seals (n = 25) were tagged with satellite relay data loggers between November 2001 and March 2003. To estimate the proportion of time spent hauled out, time at sea on foraging trips was modelled separately from haul-out behaviour close to haul-out sites because of the different factors affecting these processes. A generalised linear mixed model framework was developed to capture the longitudinal nature of the data and the repeated measures across individuals. Despite seasonal variability in the number of seals counted at haul-out sites, the model generated estimates of abundance, with an overall mean of 846 (95% CI: 767 to 979). The methodology shows the value of using count and telemetry data collected concurrently for estimating absolute abundance, information that is essential to assess interactions between predators, fish stocks and fisheries.

Massive sequencing has improved the predator diet analysis, making it possible to identify taxa with low or no detectability via traditional scatological methods. In Mexico, the Pacific harbor seal (Phoca vitulina richardii) diet has been understudied, with the importance of invertebrates or cartilaginous fish as prey currently unknown. This study aims to characterize the harbor seal diet through metabarcoding and to compare results with those obtained via the analysis of the hard remains taken from the same samples. Samples were collected at four breeding colonies during the molting season. Libraries were constructed following an Illumina dual-indexed strategy using specific eukaryote (18S rRNA), chordate and cephalopod (16S mtDNA) primers to amplify the prey's DNA, and blocking primers to avoid predator DNA amplification. Libraries were sequenced on the MiSeq ® platform (Illumina), generating 848,411 reads. The quality control and taxonomic assignment for the sequences were performed in silico using bioinformatic tools. The present study, identified 49 prey (mostly bony fish), including 14 species of invertebrates, hagfish, and elasmobranchs, thus widening knowledge of the Pacific harbor seal's diet. While 19 prey species were identified using both the hard remains and metabarcoding analysis, methods (with only four identified to genus level), lower prey richness was found in the hard remains. The main prey items around all islands were longfin sanddab (Citharichthys xanthostigma) and California lizardfish (Synodus lucioceps). Metabarcoding analysis is a new approach for studying the diet of key species in a highly productive and changing ecosystem, such as the California Current System.

Blood samples were collected from 156 free‐ranging southern elephant seals (Mirounga leonina) from Peninsula Valdes to study the variation in blood parameters related to ontogeny and the annual cycle. Samples ranged from newborn pups to adults. Interactions between age and sex showed different trends in ontogenetic changes of blood parameters (MANOVA, Wilkis' Lamb‐da12,243= 0.75, P < 0.01). The hematocrit (HCT) and hemoglobin concentration (HB) reached adult levels early in life. Weanlings had 14 % higher HCT than pups, and similar levels to juveniles and adults (HCT range = 46%‐62 %). HB of males were below those of females from weaning (18.4 vs. 20.3 g/dl) to adulthood (19.8 vs. 22.3 g/dl). Red blood cell counts (RBC) did not change significantly from pups to juveniles (2.8–3.2 106/μl), but varied for adults at different times of the annual cycle. Breeding females had higher RBC than molting females (3.1 vs. 2.4 106/μl). Changes in blood parameters are related to the develo...

Massive sequencing has improved the predator diet analysis, making it possible to identify taxa with low or no detectability via traditional scatological methods. In Mexico, the Pacific harbor seal (Phoca vitulina richardii) diet has been understudied, with the importance of invertebrates or cartilaginous fish as prey currently unknown. This study aims to characterize the harbor seal diet through metabarcoding and to compare results with those obtained via the analysis of the hard remains taken from the same samples. Samples were collected at four breeding colonies during the molting season. Libraries were constructed following an Illumina dual-indexed strategy using specific eukaryote (18S rRNA), chordate and cephalopod (16S mtDNA) primers to amplify the prey's DNA, and blocking primers to avoid predator DNA amplification. Libraries were sequenced on the MiSeq ® platform (Illumina), generating 848,411 reads. The quality control and taxonomic assignment for the sequences were performed in silico using bioinformatic tools. The present study, identified 49 prey (mostly bony fish), including 14 species of invertebrates, hagfish, and elasmobranchs, thus widening knowledge of the Pacific harbor seal's diet. While 19 prey species were identified using both the hard remains and metabarcoding analysis, methods (with only four identified to genus level), lower prey richness was found in the hard remains. The main prey items around all islands were longfin sanddab (Citharichthys xanthostigma) and California lizardfish (Synodus lucioceps). Metabarcoding analysis is a new approach for studying the diet of key species in a highly productive and changing ecosystem, such as the California Current System.

Blood samples were collected from 156 free‐ranging southern elephant seals (Mirounga leonina) from Peninsula Valdes to study the variation in blood parameters related to ontogeny and the annual cycle. Samples ranged from newborn pups to adults. Interactions between age and sex showed different trends in ontogenetic changes of blood parameters (MANOVA, Wilkis' Lamb‐da12,243= 0.75, P < 0.01). The hematocrit (HCT) and hemoglobin concentration (HB) reached adult levels early in life. Weanlings had 14 % higher HCT than pups, and similar levels to juveniles and adults (HCT range = 46%‐62 %). HB of males were below those of females from weaning (18.4 vs. 20.3 g/dl) to adulthood (19.8 vs. 22.3 g/dl). Red blood cell counts (RBC) did not change significantly from pups to juveniles (2.8–3.2 106/μl), but varied for adults at different times of the annual cycle. Breeding females had higher RBC than molting females (3.1 vs. 2.4 106/μl). Changes in blood parameters are related to the develo...

Understanding habitat use patterns of marine apex predators is of paramount importance for the effective design of conservation plans. Due to their amphibious life cycle, pinnipeds are one of the most vulnerable groups to habitat loss and degradation. Reducing knowledge gaps that still exist regarding temporal changes in tropical pinniped habitat use is therefore of particular importance for conservation efforts. We analyzed terrestrial habitat use phenology of a tropical otariid, the Galapagos sea lion Zalophus wollebaeki. Regular land-based censuses were carried out in Wreck Bay of San Cristóbal Island, Galapagos, between 2008 and 2012 to explore seasonal changes in sea lion abundance, distribution, and preferences among different habitat types. A daily cycle of haul-out patterns was observed. Animals aggregated on sandy beaches during the coldest periods of the day and were more abundant on rocky and artificial structures when air temperature was warmer. The use of artificial floating platforms as resting places by Z. wollebaeki was described for the first time and linked to environmental variability, suggesting that this may be a successful management tool for pinnipeds inhabiting low latitudes. Further, this species demonstrated seasonal distribution changes, aggregating in high densities during warm seasons and maintaining more even distributions during cold seasons. Sea surface temperature, air temperature, and the onset of the breeding season were the variables that most significantly influenced haul-out patterns of Z. wollebaeki, indicating that this species can adapt to changing environmental conditions by displaying a high degree of plasticity regarding its distribution and terrestrial microhabitat preferences.

I would especially like to thank my advisor, Dr. Markus Horning, for his continuing support, encouragement, and in reaching out with the opportunity to pursue my career goals. I genuinely thank my committee members, Dr. Douglas Reese and Kelly Benoit-Bird for their input, direction and coffee-fueled discussions along the way. Additionally, I would like to thank the Hatfield Marine Science Center and Marine Mammal Institute for their amazing communities and opportunities. Lastly, but most importantly, I would like thank my parents, family and friends. I could not have achieved my goals if it weren't for the unfaltering support and love of my family members and friends who believed in my decision to take a chance and move all the way to Oregon. This project was funded primarily through the HMSC Mamie Markham Memorial Research Fund, the Oregon Community Foundation, and through teaching assistantship opportunities within the Department of Fisheries and Wildlife. Thank you to both the faculty members I have the fortune to instruct with and also to my students; I truly hope that you were able to learn as much from me as I was from you.

An animal's physiology limits the environmental conditions where it can persist; quantifying the physiology of the walrus is timely since they are being impacted by alterations in sea ice. We examined postnatal changes in hematology, an important attribute that supports diving, by analyzing a longitudinal data set from aquaria walruses (five males and nine females) sampled from 0.04 to 12.0 years of age (n = 795 samples). Red blood cell count (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean cell hemoglobin (MCH), and mean corpuscular hemoglobin content (MCHC) did not change markedly after birth and appears to have not been influenced by sex. Estimated values at

We applied a 2-step clustering algorithm and Bayesian stable isotope mixing model to examine intraspecific differences in the contribution of prey sources to the diet and foraging habitat of harbor seals Phoca vitulina in the Salish Sea, USA. We analyzed stable isotopes of carbon and nitrogen collected from 32 seals and 248 prey samples representing 18 of 25 of the most common seal prey items identified in seal scat. Stable isotope analyses identified significant harbor seal sex-and size-based differences in diet and foraging habitat use. In comparison to males, female harbor seals had a higher contribution of prey items that were more 13 C-enriched. This result may indicate that females derived more of their δ 13 C value from nearshore versus offshore food webs, an explanation supported by movement data on this population. However, large seals of both sexes displayed a greater offshore signal in their diet, indicating that seal mass effects on foraging habitat use were somewhat independent of sex. Our work contributes to understanding trophic linkages between these generalist consumers and their prey. The foraging differences that we detected between male and female harbor seals present complex challenges for fisheries management and for the design of marine reserves. Many marine reserves in the Pacific Northwest are located in close proximity to seal haul-out sites. By lowering the energetic costs of foraging of females, these reserves may ultimately have the unintended effect of increasing individual fitness, population growth rate, and influencing future predator-induced mortality on endangered species.

There is empirical support for the efficacy of enrichment in decreasing stereotypical behaviors and increasing naturalistic behaviors in laboratory, agricultural, and zoological settings. However, little research has been done on the possible value of enrichment in facilitating appropriate behavioral development of rescued wildlife in rehabilitative captivity. Eastern Pacific harbor seal pups (Phoca vitulina richardii) often strand on the west coast of California due to maternal separation or malnutrition and need to develop skills essential for reintroduction success while in rehabilitation. In the current study, we designated four enclosures at The Marine Mammal Center in Sausalito, CA, as enrichment or control. Behavioral data were collected on 32 pups in these enclosures throughout the 2016 stranding season (April-July). In three enrichment sessions per day, pups were exposed to stimuli that elicited behaviors related to foraging and exploration (e.g., diving, tactile investigation, locomotor coordination). Stereotypical behaviors (e.g., flipper-chewing, suckling) were recorded daily when no enrichment was present. Extent of interaction with enrichment, number of stereotypical behaviors, and number of days to independently forage (free-feed) were used to determine the efficacy of enrichment for stereotypy reduction and development of foraging skills. We found a positive relationship between number of stereotypical behaviors and days to free-feed such that the more stereotypical behaviors were expressed, the more days it took the pups to free-feed (p = 0.06). When exposed to enrichment, pups displayed a trend toward fewer stereotypical behaviors than pups in a standard (unenriched) environment (p = 0.09). There were no differences in number of days it took to free-feed between enrichment and control pups but there was a negative relationship between the extent of engagement with enrichment and number of days to free-feed that approached significance (p = 0.07). This pattern of strong statistical trends suggests that enrichment can be used to reduce stereotypical behaviors and encourage naturalistic behaviors in wildlife rehabilitation settings, promoting the likelihood that rehabilitated animals will succeed when reintroduced to the wild.

Highlights • Knowledge on trophic transfer of microplastics is still scarce • By caught seals may provide information on microplastic uptake via prey • All seals had microplastics but no macroplastics were found • microplastic retention in the intestines may be related to parasite aggregations • By caught seals are a good source of data to monitor the incidence of microplastic pollution within coastal food webs *Highlights Microplastics in grey seal (Halichoerus grypus) intestines: are they associated with parasite aggregations?

Highlights • Knowledge on trophic transfer of microplastics is still scarce • By caught seals may provide information on microplastic uptake via prey • All seals had microplastics but no macroplastics were found • microplastic retention in the intestines may be related to parasite aggregations • By caught seals are a good source of data to monitor the incidence of microplastic pollution within coastal food webs *Highlights Microplastics in grey seal (Halichoerus grypus) intestines: are they associated with parasite aggregations?

In the United States, Canada, and Europe harbor seal (Phoca vitulina) pups are commonly rehabilitated after stranding and then released. Size at release is likely important to post-release survival; however, data have not been compiled to track the body condition of rehabilitated harbor seals at release across the U.S. To better understand spatiotemporal variations in harbor seal morphometrics during rehabilitation and at release, this study retrospectively analyzed body conditions, weights, lengths, and growth rates of rehabilitated harbor seal pups in the U.S. Body condition index (BCI) was calculated, and weight and BCI were modeled regionally and temporally. There was significant variation in weight, length, BCI, and growth rate for rehabilitated and released seals between the East and West Coasts of the U.S. and among different years. Growth rates during rehabilitation were slower than reported for wild pups from birth to weaning. Length at release was not a strong predictor of...

Metapopulation theory assumes a balance between local decays/extinctions and local growth/new colonisations. Here we investigate whether recent population declines across part of the UK harbour seal range represent normal metapopulation dynamics or are indicative of perturbations potentially threatening the metapopulation viability, using 20 years of population trends, location tracking data (n= 380), and UK-wide, multi-generational population genetic data (n= 269). First, we use microsatellite data to show that two genetic groups previously identified are distinct metapopulations: northern and southern. Then, we characterize the northern metapopulation dynamics in two different periods, before and after the start of regional declines (pre-/peri-perturbation). We identify source–sink dynamics across the northern metapopulation, with two putative source populations apparently supporting three likely sink populations, and a recent metapopulation-wide disruption of migration coincident...

Understanding habitat use patterns of marine apex predators is of paramount importance for the effective design of conservation plans. Due to their amphibious life cycle, pinnipeds are one of the most vulnerable groups to habitat loss and degradation. Reducing knowledge gaps that still exist regarding temporal changes in tropical pinniped habitat use is therefore of particular importance for conservation efforts. We analyzed terrestrial habitat use phenology of a tropical otariid, the Galapagos sea lion Zalophus wollebaeki. Regular land-based censuses were carried out in Wreck Bay of San Cristóbal Island, Galapagos, between 2008 and 2012 to explore seasonal changes in sea lion abundance, distribution, and preferences among different habitat types. A daily cycle of haul-out patterns was observed. Animals aggregated on sandy beaches during the coldest periods of the day and were more abundant on rocky and artificial structures when air temperature was warmer. The use of artificial floating platforms as resting places by Z. wollebaeki was described for the first time and linked to environmental variability, suggesting that this may be a successful management tool for pinnipeds inhabiting low latitudes. Further, this species demonstrated seasonal distribution changes, aggregating in high densities during warm seasons and maintaining more even distributions during cold seasons. Sea surface temperature, air temperature, and the onset of the breeding season were the variables that most significantly influenced haul-out patterns of Z. wollebaeki, indicating that this species can adapt to changing environmental conditions by displaying a high degree of plasticity regarding its distribution and terrestrial microhabitat preferences.

• Microplastic pollution is evident in surface waters of Kingston Harbour, Jamaica. • Microplastics concentration ranged from 0 to 5.73 particles/m 3 (0-2,697,674.13 particles/km 2). • Fragments were the most abundant morphology sampled from Kingston Harbour. • The average microplastic:zooplankton ratio was 0.18%.

We applied a 2-step clustering algorithm and Bayesian stable isotope mixing model to examine intraspecific differences in the contribution of prey sources to the diet and foraging habitat of harbor seals Phoca vitulina in the Salish Sea, USA. We analyzed stable isotopes of carbon and nitrogen collected from 32 seals and 248 prey samples representing 18 of 25 of the most common seal prey items identified in seal scat. Stable isotope analyses identified significant harbor seal sex-and size-based differences in diet and foraging habitat use. In comparison to males, female harbor seals had a higher contribution of prey items that were more 13 C-enriched. This result may indicate that females derived more of their δ 13 C value from nearshore versus offshore food webs, an explanation supported by movement data on this population. However, large seals of both sexes displayed a greater offshore signal in their diet, indicating that seal mass effects on foraging habitat use were somewhat independent of sex. Our work contributes to understanding trophic linkages between these generalist consumers and their prey. The foraging differences that we detected between male and female harbor seals present complex challenges for fisheries management and for the design of marine reserves. Many marine reserves in the Pacific Northwest are located in close proximity to seal haul-out sites. By lowering the energetic costs of foraging of females, these reserves may ultimately have the unintended effect of increasing individual fitness, population growth rate, and influencing future predator-induced mortality on endangered species.

required under the EU Marine Strategy Framework Directive to prevent any harm on marine ecosystems and their biota. Sampling to evaluate effects of marine litter, including microdebris, in top predators is difficult. Usually, microdebris is examined in the gastro-intestinal tract of stranded dead animals. However, the population of the endangered Mediterranean monk seal is too small for obtaining sufficient samples. The present study implemented for the first time a non-invasive technique for collecting monk seal samples to assess the microdebris ingestion in a systematic manner. A total of 12 samples of monk seal faeces were collected from marine caves in Zakynthos Island, Greece (INTERREG MED project “Plastic Busters MPAs”). A total of 166 particles were identified; 77% of the particles were smaller than 3 mm but a piece of net larger than 5 cm was also found. The majority of particles were filaments (84%), and only one sphere was found. Faeces contained on average 14 particles pe...

The Guadalupe fur seal (GFS) currently is recovering from near extinction and prey availability is an important factor. Scat and stable isotope analyses (SIA) were used to assess GFS foraging on Guadalupe Island during 2013-2016. This period was characterized by normal (2013) ocean temperatures followed by warm conditions (2014-2016). Scat samples (~40/year) were collected for prey identification. Additionally, lanugo samples from 1-month-old pups (50/year) were processed for SIA (δ 13 C/δ 15 N). Interannual prey preferences were identified (ANOSIM, p < .05), including significant differences between 2013 and the anomalous years. The most important prey species among these years was the jumbo squid; followed by the neon flying squid (2014-2016). The GFS diet was more specialized in 2013-2015 and more generalized in 2016. Prey from higher trophic levels (determined by scat analysis) were

Pinniped vibrissae provide information on changes in diet at seasonal and annual scales; however, species-specific growth patterns must first be determined in order to interpret these data. In this study, a simple linear model was used to estimate the growth rate of vibrissae from adult female California sea lions (Zalophus californianus) from San Esteban Island in the Gulf of California, Mexico. The δ15N and δ13C values do not display a marked oscillatory pattern that would permit direct determination of the time period contained in each vibrissa; thus, time (age) was calculated in two ways: 1) based on the correlation between the observed number of peaks (Fourier series) in the δ15N profile and the length of each vibrissa, and 2) through direct comparison with the observed number of peaks in the δ15N profile. Cross-correlation confirmed that the two peaks in the δ15N profile reflected the two peaks in the chlorophyll-a concentration recorded annually around the island. The mean gr...

1. There is considerable debate over the impact of seal predation on salmonid populations in both the Atlantic and Pacific oceans. Conventional hard-part analysis of scats has suggested that salmonids represent a minor component of the diet of grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) in the UK. However, it is unclear whether this is an accurate reflection of the diet or due to methodological problems. To investigate this issue, we applied quantitative PCR (qPCR) to examine the presence of salmonids in the diet of seals in the Moray Firth, UK, during the summers of 2003 and 2005. 2. Two qPCR assays were designed to detect Atlantic salmon Salmo salar and sea trout Salmo trutta DNA in field samples and experimentally spiked scats. The proportion of scats sampled in the field that were positive for salmonid DNA was low (≈ 10%). However, the DNA technique consistently resulted in more positive scats than when hard-part analysis was used. 3. An experimental study using spiked scat material revealed a highly significant negative relationship between Ct values obtained from the Atlantic salmon qPCR assay and the proportion of Atlantic salmon material added to scats. The Ct value denotes the cycle number at which the increasing fluorescence signal of target DNA crosses a threshold value. Ct values from field-collected seal scats suggested they contained a very low concentration of salmonid remains (1-5%) based on an approximate calibration curve constructed from the experimental data. 4. Synthesis and applications. The qPCR assay approach was shown to be highly efficient and consistent in detection of salmonids from seal scats, and to be more sensitive than conventional hard-parts analysis. Nevertheless, our results confirm previous studies indicating that salmonids are not common prey for seals in these Scottish estuaries. These studies support current management practice, which focuses on control of the small number of seals that move into key salmonid rivers, rather than targeting the larger groups of animals that haul-out in nearby estuaries.

Obtaining population estimates of species that are not easily observed directly can be problematic. However, central place foragers can often be observed some of the time, e.g. when seals are hauled out. In these instances, population estimates can be derived from counts, combined with information on the proportion of time that animals can be observed. We present a modelling framework to estimate seasonal absolute abundance using counts and information from satellite telemetry data. The method was tested on a harbour seal population in an area of southeast Scotland. Counts were made monthly, between November 2001 and June 2003, when seals were hauled out on land and were corrected for the proportion of time the seals were at sea using satellite telemetry. Harbour seals (n = 25) were tagged with satellite relay data loggers between November 2001 and March 2003. To estimate the proportion of time spent hauled out, time at sea on foraging trips was modelled separately from haul-out behaviour close to haul-out sites because of the different factors affecting these processes. A generalised linear mixed model framework was developed to capture the longitudinal nature of the data and the repeated measures across individuals. Despite seasonal variability in the number of seals counted at haul-out sites, the model generated estimates of abundance, with an overall mean of 846 (95% CI: 767 to 979). The methodology shows the value of using count and telemetry data collected concurrently for estimating absolute abundance, information that is essential to assess interactions between predators, fish stocks and fisheries.

Blood indices were measured in 27 species of lizard from Chile and Argentina occurring at diflerent altitudes ranging from sea-level up to 4600 m. 2. Contrary to amphibians, none of the hematological values of these lizards, such as hematocrit, hemoglobin concentration, red cell count, mean cell volume, mean cell hemoglobin and mean ccl1 hemoglobin concentration, were found to be correlated with their altitudinal distribution. 3. Intrageneric comparison of blood values in Liolaemus lizards (seven highland species living above 30Mlm and 12 lowland species) showed a similar degree of inde~nd~# from their altitudinal site of capture or from their upper limit of distribution. 4. As reported for other vertebrate taxa, an inverse correlation between size and number of red blood ceils was also found in the studied reptiles.

Carcasses of adult and subadult male Guadalupe fur seals (GFSs) are beached on Isla Magdalena, representing about 73% of all GFSs beachings since 2003. Analysis of carbon and nitrogen stable isotopes in dentin collagen from male GFSs was used in an attempt to distinguish animals from two possible locations of origin: the oceanic Guadalupe Island (GI) and the coastal San Benito Islands (SBI). Samples of conterminous and contemporary California sea lions (CSLs) were included as representative of coastal predators. Two distinct groups of GFSs were evident based on δ 13 C values: coastal GFSs with higher δ 13 C values than CSLs, and oceanic GFSs with lower δ 13 C values than CSLs. Significant temporal trends were observed in the δ 15 N values; values for oceanic GFSs and CSLs increased annually (0.082‰ and 0.089‰, respectively), while those for coastal GFS decreased annually by 0.183‰. The isotopic segregation of oceanic and coastal GFS males, presumably from GI and SBI respectively, has been present at least since the mid-1990s. This segregation may be due to dissimilar ingestion of prey from oceanic vs. coastal origin prior to their seasonal co-occurrence in the Gulf of Ulloa.

Highlights • Knowledge on trophic transfer of microplastics is still scarce • By caught seals may provide information on microplastic uptake via prey • All seals had microplastics but no macroplastics were found • microplastic retention in the intestines may be related to parasite aggregations • By caught seals are a good source of data to monitor the incidence of microplastic pollution within coastal food webs *Highlights Microplastics in grey seal (Halichoerus grypus) intestines: are they associated with parasite aggregations?

The diet of harbor seals (Phoca vitulina richardii) in San Francisco Bay (SFB), California, was determined from July 2007 to July 2008 using prey hard parts recovered from 442 scats collected at five haul-out sites. Twenty-two species of fish and one species of crustacean were identified, but harbor seals primarily ate a nonnative invasive species, yellowfin goby (Acanthogobius flavimanus), which increased in dietary importance since the diet was last studied in 1991/1992. Additionally, another nonnative invasive fish species, chameleon goby (Tridentiger trigonocephalus), was found for the first time in the diet of harbor seals in SFB. Harbor seal diet was statistically different between years (1991/1992 and 2007/2008), between the pupping and nonpupping seasons, and between North SFB and South SFB haul-out locations. The diet of harbor seals was significantly correlated with fish species caught in trawl surveys conducted by the California Department of Fish and Wildlife (CDFW) during the same time periods as this study (2007/2008). Harbor seals currently are influencing the health of the SFB ecosystem in a positive manner by consuming large quantities of nonnative invasive fish species.

Community marine reserves are geographical areas closed to fishing activities, implemented and enforced by the same fishermen that fish around them. Their main objective is to recover commercial stocks of fish and invertebrates. While marine reserves have proven successful in many parts of the world, their success near important marine predator colonies, such as the California sea lion (Zalophus californianus) and the Pacific harbor seal (Phoca vitulina richardii), is yet to be analyzed. In response to the concerns expressed by local fishermen about the impact of the presence of pinnipeds on their communities' marine reserves, we conducted underwater surveys around four islands in the Pacific west of the Baja California Peninsula: two without reserves (Todos Santos and San Roque); one with a recently established reserve (San Jeronimo); and, a fourth with reserves established eight years ago (Natividad). All these islands are subject to similar rates of exploitation by fishing cooperatives with exclusive rights. We estimated fish biomass and biodiversity in the seas around the islands, applying filters for potential California sea lion and harbor seal prey using known species from the literature. Generalized linear mixed models revealed that the age of the reserve has a significant positive effect on fish biomass, while the site (inside or outside of the reserve) did not, with a similar result found for the biomass of the prey of the California sea lion. Fish biodiversity was also higher around Natividad Island, while invertebrate biodiversity was higher around San Roque. These findings indicate that marine reserves increase overall fish diversity and biomass, despite the presence of top predators, even increasing the numbers of their potential prey. Community marine reserves may help to improve the resilience of marine mammals to climate-driven phenomena and maintain a healthy marine ecosystem for the benefit of both pinnipeds and fishermen.

The feeding ecology of juvenile and subadult Guadalupe fur seals (Arctocephalus townsendi) at San Benito Archipelago, Baja California, Mexico, was investigated to determine if dietary differences exist between these two age classes. During the summer of 2007, 108 scats of fur seals were collected from areas used mainly by juveniles (n = 54 scats) or subadults (n = 54 scats). Cephalopod beaks and/or otoliths were found in all samples collected. Only 702 squid beaks of 1,144 were identified to species level (61.3%). Only four of eight otoliths found were identified to species level (50%). Six squid species and two fish species were identified. Both juveniles and subadults showed similar dietary composition; however, differences between prey selection were found. The California market squid (Loligo opalescens) was the most common squid species for both age classes in the summer of 2007.

The Guadalupe fur seal (GFS, Arctocephalus townsendi) was distributed on the islands of Baja California, Mexico, and southern California, United States. The species was intensively hunted during the 19th century, and in the late 1920s it was thought that it was extinct, but in 1954, a few animals were located on Isla Guadalupe, Baja California. Since the current status of the GFS population is unknown, we used counts of pups collected between 1984 and 2013 from Isla Guadalupe, which is still the only place where the species reproduces, and used Bayesian inference to assess both the population trend and abundance. The GFS population increased from 1984 to 2013 at an average annual growth rate of 5.9% (range 4.1-7.7%), and for 2013 the abundance was estimated between 34,000 and 44,000 individuals. The current abundance of the GFS represents about one-fifth of the estimated historical population size, and although the population has continued to increase, the species has not expanded its breeding range, which potentially affects its recovery. El lobo fino de Guadalupe (GFS, Arctocephalus townsendi) se distribuía en las islas de Baja California, México y del sur de California, United States. El GFS fue cazado intensamente durante el siglo XIX, y hacia finales de la década de 1920 se pensó que estaba extinguido; sin embargo en 1954 algunos animales se localizaron en la Isla Guadalupe, Baja California. Debido a que el estado actual de la población del GFS se desconoce, recopilamos conteos de crías realizados entre 1984 y 2013 en Isla Guadalupe, que es el único lugar donde la especie se reproduce y usamos inferencia Bayesiana para evaluar la tendencia de la población y su abundancia. La población del GFS se incrementó de 1984 a 2013 a una tasa media anual de 5.9% (con un rango de 4.1-7.7%) y para el 2013 el tamaño poblacional se estimó entre 34,000 y 44,000 individuos. La abundancia actual del GFS representa alrededor de la quinta parte del tamaño poblacional histórico estimado y aunque la población continúa incrementándose, la especie no ha expandido su área geografica de reproducción, lo que potencialmente puede afectar su recuperación.

Although the California sea lion (Zalophus californianus) is the only pinniped resident in the Gulf of California, there are occasional records of 3 additional species; here we report 4 recent records of the Guadalupe fur seal (Artocephalus townsendi), 6 of the northern elephant seal (Mirounga angustirostris) and 2 of the harbor seal (Phoca vitulina). Harbor seals have been observed mostly during the winter-spring months of El Nino years, before water temperature warms in the summer. It is possible that juveniles and subadult and adult males of A. townsendi and M. angustirostris are using the Gulf as an alternative feeding area during the season of intensive feeding as individuals disperse more and more widely as their populations grow.

This study documents microplastics (MPs) in the top three commercially sold fishes viz. Auxis rochei , Rastrelliger kanagurta and Chanos chanos in major public markets of Cebu Island, Philippines. MPs were found in the gastrointestinal tracts (FGIT) and quantified and characterized according to size, type, and color. In general, nine (97.3%) of 81 FGIT samples contained 635 total pieces of MPs with size ranging 0.01 to 0.50 and 1.00 to 2.00 mm. Transparent microfibers (91%) were the most predominant MPs, with blue (48%) as the most common MP color observed, followed by red (39%), black (8%) and white (5%). Chanos chanos proved to be the most susceptible fish to MP ingestion with a mean average of 11.6 pieces per individual fish, followed by A. rochei with 6.6 pieces, and R. kanagurta with 5.3 pieces. The results indicated that MPs were ubiquitous and high in commercially sold fishes in major public wet markets of Cebu Island, Philippines. The ingestion of fishes is of primary concer...

Background There are approximately 10,000–12,000 Pacific harbor seals (Phoca vitulina richardii) inhabiting the Oregon coast, and unlike other species of pinnipeds in this region, are reliably present year-round. Despite this, and drastic rebounds in population since the enactment of the Marine Mammal Protection Act, limited data is available for the present period regarding their space use at sea, and within estuarine, riverine, or bay areas within the state. Objective To examine site-based differences in space use for 24 adult Pacific harbor seals captured and outfitted with satellite transmitters at two predominant haulout sites on the Oregon Coast, USA. Design We captured 24 adult harbor seals from two haulout sites on the Central Oregon coast between September 2014–16 and fitted them with external Wildlife Computers SPOT5 satellite transmitters to track movement. Using state-space modeled locations derived from satellite telemetry data, we evaluated spatial behavior of these an...

1Laboratorio de Ecofisiología, Centro de Investigación en Alimentación y Desarrollo, AC Unidad Guaymas, Carretera a Varadero Nacional km 6.6, Col. Las Playitas, Guaymas, Sonora, 85480, México. 2Instituto Nacional de Ecología-SEMARNAT, Programa de Mamíferos ...

Weddell seals (Leptunycbotes weddellii) give birth and nurse their pups on areas of fast ice along the coast of Antarctica. Starting from two weeks after parturition, females spend increasingly more time in the water (Thomas and DeMaster 19836). Kooyman (1968) characterized the diving behavior of adult Weddell seals, and considered dives deeper than 200 m and of between 8 and 15 min duration to be associated with hunting. Testa et al. (1989) suggested that Weddell seal mothers might feed opportunistically during lactation because they repeatedly dove to depths over 100 m and that such deep dives increased in frequency as weaning approached. Sato et al. (2002) attached digital still cameras to free-ranging Weddell seal mothers and presented photographic evidence of their foraging behavior at depths of around 300 m. Weddell seal mothers spent 7%-74% of their time on shallow dives (<50 m) and at the sea surface, although the function of the shallow dives was unknown (Sato et al. 2002). Female phocid seals spend time in the water for various reasons, including foraging, avoidance of predators and harsh environmental conditions, and participation in social activities (Lydersen and Kovacs 1999). Some observations have provided insight into the social interactions between Weddell seal mothers 3 84

1Laboratorio de Ecofisiología, Centro de Investigación en Alimentación y Desarrollo, AC Unidad Guaymas, Carretera a Varadero Nacional km 6.6, Col. Las Playitas, Guaymas, Sonora, 85480, México. 2Instituto Nacional de Ecología-SEMARNAT, Programa de Mamíferos ...