Fur Seals Research Articles

Late Holocene variation in the Hard prey remains and stable isotope values of penguin and seal tissues from the Danger Islands, Antarctica

Ornithogenic soils in Antarctica provide a biological archive of the occupation history and trophic ecology of penguins and other marine species over geological timescales. Hard prey remains and predator tissues, which are well preserved in ornithogenic soils, can act as paleoecological proxies of past environmental conditions. Here we examine ornithogenic soils from an active colony of Pygoscelis spp. penguins on Platter Island in the Danger Islands Archipelago along the northeastern side of the Antarctic Peninsula. We radiocarbon dated penguin tissues from excavated ornithogenic soils and parameterized an age-depth model of penguin occupation history. Hard prey remains were enumerated and recovered Pygoscelis spp. penguin and Antarctic fur seal (Arctocephalus gazella) tissues were analyzed for stable isotopes carbon (δ13C) and nitrogen (δ15N) analysis. The oldest recovered ornithogenic soils at Platter Island date to 502–653 years BP and coincide with the start of a period of increased warming and glacial discharge in the northeastern Antarctic Peninsula. Penguin tissues δ15N values increased between the oldest and youngest dated ornithogenic soils but seal tissues did not. This may indicate that the trophic level of penguins, but not seals, has increased over time, a hypothesis supported by the concurrent increase in the hard prey remains of fish and squid taxa common to penguin diets recovered from ornithogenic soils. Future studies of ornithogenic soils in the Danger Islands Archipelago are warranted to test this hypothesis and assess the potential confounding effects of varying ecosystem isotopic baselines and penguin species composition over time.

Isolation and genome sequencing of Staphylococcus schleiferi subspecies coagulans from Antarctic and North Sea seals.

Reports on the commensal organism and opportunistic pathogen Staphylococcus schleiferi have largely considered isolates from humans and companion dogs. Two subspecies are recognized: the coagulase-negative S. schleiferi ssp. schleiferi, typically seen in humans, and the coagulase-positive S. schleiferi ssp. coagulans, typically seen in dogs. In this study, we report the isolation, genome sequencing and comparative genomics of three S. schleiferi ssp. coagulans isolates from mouth samples from two species of healthy, free-living Antarctic seals, southern elephant seals (Mirounga leonina) and Antarctic fur seals (Arctocephalus gazella), in the South Orkney Islands, Antarctica, and three isolates from post-mortem samples from grey seals (Halichoerus grypus) in Scotland, UK. This is the first report of S. schleiferi ssp. coagulans isolation from Antarctic fur seal and grey seal. The Antarctic fur seal represents the first isolation of S. schleiferi ssp. coagulans from the family Otariidae, while the grey seal represents the first isolation from a pinniped in the Northern Hemisphere. We compare seal, dog and human isolates from both S. schleiferi subspecies in the first genome-based phylogenetic analysis of the species.

Colonization of the ancient southern oceans by small-sized Phocidae: new evidence from Australia

AbstractMost of the diversity of extant southern true seals (Phocidae: Monachinae) is present in the Southern Ocean, but a poor fossil record means that the origin of this fauna remains unknown. Australia represents a large gap in the record bordering the Southern Ocean that could possibly inform on the origins of the extant Antarctic monachines, with most known fossils remaining undescribed. Here we describe the oldest Australian fossil pinniped assemblage, from the Late Miocene to the Early Pliocene of Beaumaris. Two fossils are referrable to Pinnipedia, five (possibly six) to Phocidae and a humerus is referrable to Monachinae. The humerus is not referrable to any extant tribe, potentially representing an archaic monachine. The description of this assemblage is consistent with the Neogene pinniped fauna of Australia being exclusively monachine before the arrival of otariids (fur seals and sea lions). The Beaumaris humerus, along with other Neogene phocids from the Southern Ocean margins, were smaller than their extant Antarctic relatives, possibly driven by longer food chains with less energy efficiency between trophic levels. This suggests that small archaic phocids potentially used the Southern Ocean as a means of dispersal before the arrival of extant Antarctic monachines.

Current status of pinnipeds phylogeny based on molecular and morphological data

ABSTRACT The disagreement surrounding the relationship within pinnipeds as well as their phylogenetic affinities still remains unresolved. Molecular-based studies neglect significant morphological data and ignore the entire fossil record, which demonstrates why there are such contradicting results from morphology-based studies. There still remains a difference of opinion about the origin of pinnipeds, with research supporting origination from either Ursid (bear-like) or Mustelid (weasel-like) ancestors, even extending down to familial and subfamilial levels. This study examines certain morphological characters in the three pinniped families: Otariidae (sea lions and fur seals), Odobenidae (walruses), and Phocidae (true seals), with extra emphasis on the four phocid subfamilies: Phocinae, Monachinae, Cystophorinae, and Devinophocinae. Morphological characters of the cranium (skull, dentition and mandible) and post cranium (humerus and femur) are the basis for understanding pinnipeds’ movement, body size, and sexual dimorphism, and all are ignored when only molecular analyses are used. Biomolecular based studies involve larger sample sizes and incorporate more phylogenetic characters, but ignore the significant data from the fossil record (which can only be examined through morphology). Therefore, the origin of pinnipeds cannot be resolved by depending only on molecular (genetic) or morphological approaches independently and future studies need to integrate both morphology and molecular data.

An 85K SNP Array Uncovers Inbreeding and Cryptic Relatedness in an Antarctic Fur Seal Breeding Colony.

High density single nucleotide polymorphism (SNP) arrays allow large numbers of individuals to be rapidly and cost-effectively genotyped at large numbers of genetic markers. However, despite being widely used in studies of humans and domesticated plants and animals, SNP arrays are lacking for most wild organisms. We developed a custom 85K Affymetrix Axiom array for an intensively studied pinniped, the Antarctic fur seal (Arctocephalus gazella). SNPs were discovered from a combination of genomic and transcriptomic resources and filtered according to strict criteria. Out of a total of 85,359 SNPs tiled on the array, 75,601 (88.6%) successfully converted and were polymorphic in 270 animals from a breeding colony at Bird Island in South Georgia. Evidence was found for inbreeding, with three genomic inbreeding coefficients being strongly intercorrelated and the proportion of the genome in runs of homozygosity being non-zero in all individuals. Furthermore, analysis of genomic relatedness coefficients identified previously unknown first-degree relatives and multiple second-degree relatives among a sample of ostensibly unrelated individuals. Such “cryptic relatedness” within fur seal breeding colonies may increase the likelihood of consanguineous matings and could therefore have implications for understanding fitness variation and mate choice. Finally, we demonstrate the cross-amplification potential of the array in three related pinniped species. Overall, our SNP array will facilitate future studies of Antarctic fur seals and has the potential to serve as a more general resource for the wider pinniped research community.

Southern Ocean isoscapes derived from a wide-ranging circumpolar marine predator, the Antarctic fur seal

The large-scale spatial patterns and primary drivers of food web dynamics across seascapes can be investigated using isotope ratios in marine consumers. However, interpreting complex signatures from mobile animals can require good knowledge of spatial isotopic variations in the environment. This is particularly true in the Southern Ocean where regional differences in the physical environment affect habitat predictability and predator foraging. We applied a retrospective-isotope approach integrated with tracking locations for a model species, the Antarctic fur seal (Arctocephalus gazella), to generate large-scale spatially-explicit predictions of isotopic gradients (“isoscapes”) across the Southern Ocean. Vibrissae and blood samples were collected during post- and pre-breeding periods from both Antarctic and sub-Antarctic breeding environments. Stable isotope values from vibrissae growth and serially sampled blood enabled the reconstruction of an isotopic time-series that could be directly related to feeding locations at sea. Tracked seals were widely distributed in the southern Atlantic and Indian Oceans, with important foraging activity centred on productive upwelling areas, oceanic frontal zones and shelf environments. Corresponding seal δ13C and δ15N values were positively correlated to the Southern Ocean latitudes at which the tracked individuals foraged. Breeding site, bi-monthly foraging period and foraging location all explained significant variation in isotopic values during migration. Isotopic variation was largely driven by the latitudinal and inshore/offshore gradient in δ13C and δ15N at the base of the food web in neritic and oceanic waters. These delineate the spatio-temporal isotopic variability of important foraging habitats, providing a valuable perspective on the spatial and seasonal distribution of predators and forage availability. Differences in inferred predator distribution within and between breeding locations have implications for relative exposure to anthropogenic threats from fisheries interactions and climate change. This study demonstrates that isotope tracers in archival tissues are useful indicators of resource partitioning by marine consumers to directly inform spatial conservation planning and ecosystem management strategies at the cross-basin scale.

Ecological implications of unprecedented warm water anomalies on interannual prey preferences and foraging areas of Guadalupe fur seals

AbstractThe 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 (δ13C/δ15N). 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 consumed during 2014–2016, but with significantly lower δ13C/δ15N values than in 2013 (ANOVA,p < .05 for both isotope ratios). This pattern may indicate more northerly or offshore foraging areas, with the presence of oceanic prey (neon flying squid). The widest isotopic niche was observed in 2015 (2.2‰2), reflecting a broader foraging area. Our findings are an important step toward better understanding the impacts of climate change on the recovery of GFS.

Incidental catch of marine organisms registered in the Chilean Antarctic krill fishery, years 2012-2016

Krill (Euphausia superba) catch is currently the most relevant fishery industry in Antarctic waters. This resource is a keystone species in the Antarctic food web, sustaining the contribution to the trophic ecology of many invertebrate and vertebrate species. To catch krill, part of the fleet in this fishery uses large mid-water nets that also retain a diversity of other organisms like plankton, meroplankton, and fish species as bycatch. Therefore, it is necessary to understand and evaluate the magnitude of this incidental catch, as well as the potential interactions between krill fishing gear with seabirds and mammals. To estimate the composition and extent of bycatch for this fishery included 784 samples of 25 kg and an equal number of 1 kg sub-samples obtained from Antarctic krill catches in Subarea 48, between years 2012 and 2016. A total of 15 fish species were identified along with the record of five other taxa and other unidentified specimens. The most relevant fish species bycaught by weight were mackerel icefish Champsocephalus gunnari, South Georgia icefish Pseudochaenichthys georgianus, and painted notie Lepidonotothen larseni. Additionally, 20 interactions with seabirds and nine interactions with Antarctic fur seals (Arctocephalus gazella) were registered. In the five years of operations, only three seabirds died, and only two individuals of A. gazelle caught by the net were killed.

Seal-skinners lobeando en territorio chono, aónikenk y chilote, 1830-1845

Towards the end of the XVIII century and the beginning of the XIX century, in the context of a period of expansion on the part of European nations and the nascent North American republic, the commercial hunting of fur seals began to develop, and in this sense, the southern end of America became one of the main areas of their incursions. This work seeks to contribute to know more background regarding the presence of this group of navigators, in relation to the sustained interaction with the austral aborigines, as well as, regarding hunting activities. The study is based on unpublished documents, specifically American sealing ship logs. It is hypothesized that this commercial activity was much more than a transitory wandering dedicated to obtaining and collecting skins for distant markets, on the contrary, fur-seal hunters established a close relationship with the aborigines who populated these territories, in addition to generating a gradual process of familiarization with geography.

No evidence of microplastics in Antarctic fur seal scats from a hotspot of human activity in Western Antarctica

Microplastics are present in almost all seas and oceans, including the Southern Ocean. To the south of the Antarctic Polar Front, microplastics are present mainly west to the Antarctic Peninsula, but information is scarce about their impact on the pelagic food web. Here, we analysed 42 scats of male Antarctic fur seals (Arctocephalus gazella) collected in late summer at Deception Island (South Shetland Islands), which allowed us to assess the presence of microplastics in the pelagic food web of the Bransfield Strait (Western Antarctica). Furthermore, we analysed the hard remains of prey in the scats to characterize the diet of fur seals. Hard remains recovered from the scats revealed that male Antarctic fur seals foraged on krill and myctophid fishes during late summer. Fourier-transform infrared spectroscopy (FT-IR) revealed that none of the seven fragments and three fibres recovered from their scats were microplastics, but rather were silicate minerals and chitin. These results suggest that the levels of microplastic pollution in the pelagic food web of the Bransfield Strait are extremely low.

Sub-Antarctic fur seals depredate northern rockhopper penguins at Nightingale Island, Tristan da Cunha

The most plausible hypothesis for declining population trends of some marine top predators at the northern extent of their breeding ranges in the Southern Ocean is that it results from environmental change. Sub-Antarctic fur seals Arctocephalus tropicalis are opportunistic and pelagic foragers that feed on a variety of fish, cephalopods, and crustaceans throughout their range. Penguins are also targeted, but to what extent remains uncertain, with only two records to date: Amsterdam Island, South Indian Ocean, where they kill and feed on northern rockhopper penguins Eudyptes moseleyi; and Gough Island, the southernmost island in the Tristan da Cunha archipelago, South Atlantic Ocean, where they are suspected to be significant predators of northern rockhopper penguins based on an unprecedented number of penguin carcasses (> 100) found floating at sea in 2011. We report the first documented records of such predations from the northern islands in the Tristan archipelago. Over three austral summers (2015–2017), northern rockhopper penguins with severe injuries were frequently observed at Nightingale Island. The cause of the wounds was unknown, but seal or shark attacks seemed probable. In January 2019, the first confirmed sighting of a sub-Antarctic fur seal, predating a healthy northern rockhopper penguin at sea off Nightingale Island was recorded. It remains uncertain whether the large A. tropicalis population at the Tristan da Cunha islands is significant predators of northern rockhopper penguins, but this could partly explain the significant recent decrease in northern rockhopper penguin population numbers.

Considering Indigenous Peoples and local communities in governance of the global ocean commons

The United Nations are currently negotiating a new international legally-binding instrument to govern the global ocean commons, a vast area beyond national jurisdiction (ABNJ) owned by everyone but not cared for by any single entity. Indigenous Peoples and local communities (IPLCs) have been underrepresented in the debate about governance of ABNJ despite their internationally recognized rights and their role as custodians of many globally-significant migratory species that travel between coasts and high seas. Here we use examples of active transboundary connectivity by migratory species as case studies to highlight the relevance of IPLCs on islands, coasts and beyond to the governance of the global ocean commons, and make a case for their essential and beneficial inclusion in it. Many migratory species are culturally and economically important to IPLCs, who are frequently the first to suffer if these species are overexploited or decline due to inadequate management in ABNJ. Four case studies (Pacific salmon, Marine Turtles, Black-footed and Laysan Albatrosses, Northern fur seal) illustrate knowledge, innovations and practices of IPLCs that have global importance in informing strategies for conservation, sustainable and equitable use of marine species in general. IPLCs can contribute to enriching the diversity of approaches and solutions, and by elaborating on principles directly relevant for governance of ABNJ within the UN process and beyond.

Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size

BackgroundResolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming Antarctic Peninsula region. Previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited information, leopard seal diets remain unresolved by seal sex, individual, body size, region, and season. Over the 2013, 2014, and 2017 field seasons we collected scat, tissue samples (red blood cells and plasma; n = 23) for stable isotope analyses, and previously-reported animal-borne video from 19 adult leopard seals foraging near mesopredator breeding colonies at Cape Shirreff, Livingston Island. We summarized a priori diet information from scat and video analysis and applied a three-isotope (δ13C, δ15N, δ34S), four-source (fish, fur seal, krill, penguin) Bayesian mixing model to examine temporal variability in both prey sources and leopard seal tissues.ResultsThe austral spring diets of males and females focused on Antarctic krill (31.7–38.0%), notothen fish (31.6–36.5%), and penguin (24.4–26.9%) and were consistent across all 3 years. Several lines of evidence suggest the transition to summer foraging was distinct for males and females. Female diets transitioned rapidly to higher δ15N values (+2.1‰), indicating increased consumption of penguin (29.5–46.2%) and energy-dense Antarctic fur seal pup (21.3–37.6%).ConclusionsThe seasonal increase in leopard seal δ15N values, and thus fur seal in their diet, was predictably related to larger body size; it may also be forcing reductions to the largest Antarctic fur seal colony in the Antarctic Peninsula. Our ensemble sampling approach reduces historical biases in monitoring marine apex predator diets. Further, our results are necessary to best inform regional fisheries management planning.

Host Population Expansion and the Genetic Architecture of the Pinniped Hookworm Uncinaria lucasi

The long-term fidelity of pinniped hosts to their natal rookery site suggests the genetic architecture of their Uncinaria spp. hookworms should be strongly structured by host breeding biology. However, historical events affecting host populations may also shape parasite genetic structure. Sequences of the mitochondrial cytochrome c oxidase 1 (COI) gene of 86 Uncinaria lucasi individuals were obtained to assess genetic variation and structure of nematodes from 2 host species (68 hookworms from northern fur seals; 18 hookworms from Steller sea lions) and rookeries from 3 widely separated geographic regions: the western Bering Sea and Sea of Okhotsk, eastern Bering Sea, and the eastern Pacific Ocean. High COI haplotype (h = 0.96-0.98) and nucleotide (π = 0.014) diversity was found. The haplotype network showed a star-shaped pattern with a large number of haplotypes separated by few substitutions. The network did not show separation of U. lucasi by geographic region or host species. Fst values between U. lucasi individuals representing geographic regions showed no differentiation, consistent with the absence of genetic structure. At face value, this lack of genetic structure in U. lucasi suggests high gene flow but could also be explained by recent (post-glacial) population expansions of northern fur seals and their hookworms.

Fur Seal Feces-Associated Circular DNA Virus Identified in Pigs in Anhui, China

Fur seal feces-associated circular DNA virus (FSfaCV) is an unclassified circular replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA virus that has been detected in mammals (fur seals and pigs). The biology and epidemiology of the virus remain largely unknown. To investigate the virus diversity among pigs in Anhui Province, China, we pooled 600 nasal samples in 2017 and detected viruses using viral metagenomic methods. From the assembled contigs, 12 showed notably high nucleotide acid sequence similarities to the genome sequences of FSfaCVs. Based on these sequences, a full-length genome sequence of the virus was then obtained using overlapping PCR and sequencing, and the virus was designated as FSfaCV-CHN (GenBank No. MK462122). This virus shared 91.3% and 90.9% genome-wide nucleotide sequence similarities with the New Zealand fur seal strain FSfaCV-as50 and the Japanese pig strain FSfaCV-JPN1, respectively. It also clustered with the two previously identified FSfaCVs in a unique branch in the phylogenetic tree based on the open reading frame 2 (ORF2), Rep-coding gene, and the genome of the reference CRESS DNA viruses. Further epidemiological investigation using samples collected in 2018 showed that the overall positive rate for the virus was 56.4% (111/197) in Anhui Province. This is the first report of FSfaCVs identified in pigs in China, and further epidemiological studies are warranted to evaluate the influence of the virus on pigs.

Dentigerous cyst in a South African fur seal (Arctocephalus pusillus pusillus)

The dental pathology of pinnipeds has been well studied with periodontal disease the most common dental pathology accounting for 19.4–91.8 per cent of all dental pathologies. An eight‐month‐old stranded South African fur seal (Arctocephalus pusillus pusillus) was rescued from the south coast of South Africa; during his rehabilitation process his handlers noticed the absence of his left maxillary canine tooth (204). Eleven years later, during a health examination, the veterinarian upon closed examination could visualise approximately 5 mm of a tooth crown in the area where tooth 204 should have been. A presumed diagnosis of a dentigerous cyst was made based on the radiological findings. Surgery was performed to surgically extract 204 and enucleate the cyst lining. The histological analysis of the enucleated cyst lining confirmed the first reported case of a dentigerous cyst in a marine mammal.

Temporal and population trends in human exploited pinnipeds from Tierra del Fuego

Archaeological sites on the coast of Tierra del Fuego, Argentina, provide a biogeochemical record that can inform us about those ecological dynamics. An abundance of southern fur seal (Arctocephalus australis) and southern sea lion (Otaria flavescens) remains provide a valuable resource to reconstruct ancient and modern food webs. To quantify ecological relationships, we measured bulk stable isotope ratios from bone collagen in otariids and other associated animals, several of which are potential otariid prey. Variations in bulk stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) are linked to potential dietary differences and habitat specialization between coastal areas or the open ocean in populations ranging in age from 7000 cal. Years BP to modern. We observed increases in the variability of these isotopic compositions over time, which suggests a diversity in the diets and habitats of otariids. Shifts in marine food webs occurred during the transition from subsistence hunting of otariids to industrial hunting and expanded human influence. We conclude that direct human influences, such as hunting and habitat alteration, were the major drivers of ecological change in southern South American marine ecosystems.

Visual timing abilities of a harbour seal (Phoca vitulina) and a South African fur seal (Arctocephalus pusillus pusillus) for sub- and supra-second time intervals

Timing is an essential parameter influencing many behaviours. A previous study demonstrated a high sensitivity of a phocid, the harbour seal (Phoca vitulina), in discriminating time intervals. In the present study, we compared the harbour seal’s timing abilities with the timing abilities of an otariid, the South African fur seal (Arctocephalus pusillus pusillus). This comparison seemed essential as phocids and otariids differ in many respects and might, thus, also differ regarding their timing abilities. We determined time difference thresholds for sub- and suprasecond time intervals marked by a white circle on a black background displayed for a specific time interval on a monitor using a staircase method. Contrary to our expectation, the timing abilities of the fur seal and the harbour seal were comparable. Over a broad range of time intervals, 0.8–7 s in the fur seal and 0.8–30 s in the harbour seal, the difference thresholds followed Weber’s law. In this range, both animals could discriminate time intervals differing only by 12 % and 14 % on average. Timing might, thus be a fundamental cue for pinnipeds in general to be used in various contexts, thereby complementing information provided by classical sensory systems. Future studies will help to clarify if timing is indeed involved in foraging decisions or the estimation of travel speed or distance.

Environmental drivers of oceanic foraging site fidelity in central place foragers

Finding food is crucial to the survival and reproductive success of individuals. Fidelity to previous profitable foraging sites may bring benefits to individuals as they can allocate more time to foraging rather than searching for prey. We studied how environmental conditions influence when lactating long-nosed fur seals (Arctocephalus forsteri) adopt a risky (low fidelity) or conservative (high fidelity) foraging strategy at two intra-annual temporal scales when foraging in a highly variable oceanic environment. Core foraging areas (CFAs; n = 534; 30 × 30 km cells) of consecutive foraging trips were obtained from geolocation tracks of 12 females from summer to winter in 2016 (n = 5) and 2017 (n = 7). We used the spatial variability (standard deviation) of CFAs between or among oceanic foraging trips as a proxy for individual foraging site fidelity (IFSF). Over the entire oceanic foraging period (n = 12), IFSF in the latitudinal axis increased with stronger sea-surface temperature gradient (SSTgrad), but decreased with greater SSTgrad and sea-surface height gradient variability. Over a period of two consecutive oceanic foraging trips (n = 66), IFSF decreased with greater SSTgrad variability in the earlier foraging trip. LNFS show evidence that they use IFSF as a strategy to potentially optimise food acquisition, and that this behaviour is influenced by mesoscale oceanographic parameters.

Inferring diet, feeding behaviour and causes of mortality from prey-induced injuries in a New Zealand fur seal.

New Zealand fur seals Arctocephalus forsteri are the most abundant of the 4 otariid (eared seal) species distributed across Australasia. Analyses of stomach contents, scats and regurgitates suggest a diet dominated by bony fish and squid, with cartilaginous species (e.g. sharks and rays) either absent or underrepresented because of a lack of preservable hard parts. Here we report on a subadult specimen from south-eastern Australia, which was found ashore emaciated and with numerous puncture wounds across its lips, cheeks, throat and the inside of its oral cavity. Fish spines embedded in the carcass revealed that these injuries were inflicted by chimaeras and myliobatiform rays (stingrays and relatives), which matches reports on the diet of A. forsteri from New Zealand, but not South Australia. Shaking and tearing of prey at the surface may help to avoid ingestion of the venomous spines, perhaps contributing to their absence from scats and regurgitates. Nevertheless, the number and severity of the facial stab wounds, some of which led to local necrosis, likely affected the animal's ability to feed, and may account for its death. Despite their detrimental effects, fish spine-related injuries are difficult to spot, and may be a common, albeit cryptic, type of trauma. We therefore recommend that stranded seals be systematically examined for this potentially life-threatening pathology.