Hydrurga Research Articles

Calling underwater is a costly signal: size-related differences in the call rates of Antarctic leopard seals.

It is proposed that where sexually selected vocal communication is an honest signal, the call production rate is predicted to change throughout the breeding season. Male leopard seals call underwater for many hours each day over their three- to four-month breeding season, and it is hypothesized that a decrease in calling rate would be associated with the declining body condition of smaller males. The calling rates of leopard seals were measured (N = 49 recordings) and compared between seals of different size classes throughout the breeding season. Male leopard seals produce their calls at more stable rates as they become larger. In this study, larger male leopard seals adopted a strategy of consistent underwater calling throughout the breeding season, whereas there was a breakdown in the calling stereotypy of the smaller males at its height. Toward the end of the breeding season, the smaller seals produced fewer calls in shortened calling bouts, and they took more rest periods. Therefore, underwater calling may represent an honest signal in the leopard seal. For marine mammals that call underwater, the production of repetitive sequences advertises the breath-holding ability of the caller to the listeners, and this ability may be related to male stamina and endurance, thus representing an honest signal that could be widespread in other species.

Monitoring Wildlife and their Habitats in the Southern Ocean and around Indian Research Stations in Antarctica

Antarctica and its surrounding ocean are at the centre stage of rapid and extreme environmental events due to prevailing global climate change, which in turn necessitates long-term monitoring of wildlife and their habitats in this region. Systematic monitoring of seabirds and marine mammals were carried out during five austral summers (2008-09, 2009-10, 2013-14, 2014-15 and 2015-16). Vessel-based surveys for pelagic seabirds in the southern Indian Ocean, aerial surveys for seals and penguins and field surveys for locating nesting sites of Antarctic birds were conducted at Indian area of operation in Antarctica. Forty-nine species of seabirds were observed during the vessel-based surveys. Species richness peaked in the mid-latitudes but species abundances increased along higher latitudes towards Antarctica. Planktivorous species in the lower latitudes were replaced by mixed prey dependent species in the higher latitudes. Aerial surveys recorded a total of four species of seals viz. Weddell seal, Crabeater seal, Leopard seal and Ross seal and two penguin species viz. Emperor penguin and Adelie penguin. Out of 15 islands in Larsemann hills that were surveyed on-foot, the presence of nesting sites of seabirds is reported from 13 islands. The preliminary results from our study provide the baseline data for ecologically important species within Indian area of operation in Antarctica and will help design future research activities.

Vagrant leopard seal at Tristan da Cunha Island, South Atlantic

Leopard seals Hydrurga leptonyx breed in the Antarctic pack ice, but individuals may wander farther north. Only two records exist from Gough Island (40°S, 10°W) situated 360 km to the SW of Tristan da Cunha Island, in the central South Atlantic Ocean. We report the first record from Tristan da Cunha (37°S, 12°W) in September 2016. The juvenile male was lean, in poor condition, and had minor injuries. Its hindquarters were covered in stalked barnacles, which suggest that it had spent a long period at sea.

Weddell seal (Leptonychotes weddellii) killing Gentoo Penguin (Pygoscelis papua) at Neko Harbour, Antarctic Peninsula

Weddell seals (Leptonychotes weddellii) typically prey on fish, cephalopods, and invertebrates. While other seal species also include penguins as part of their regular diet, such as leopard seals, this behavior seems unusual for Weddell seals. Here, we describe an opportunistic observation of a Weddell seal attacking and killing a Gentoo Penguin (Pygoscelis papua) at Neko Harbour, Antarctic Peninsula. This behavior has rarely been observed and published. Yet, we collected several additional anecdotal observations from various regions around Antarctica, indicating that this behavior might be more common than previously assumed, challenging our current understanding of Weddell seal foraging ecology.

Shawn Loves Sharks by Curtis Manley

Reviewed by: Shawn Loves Sharks by Curtis Manley Elizabeth Bush Manley, Curtis Shawn Loves Sharks; illus. by Tracy Subisak. Roaring Brook, 2017 30p ISBN 978-1-62672-134-0 $17.99 R 4-7 yrs To say Shawn loves sharks is an understatement; obsession or mania might be better terms. When he’s not drawing sharks or reading about sharks or watching shark movies, he’s channeling sharks and terrorizing kids on the playground with his CHOMP CHOMP CHOMP-ing. There’s trouble in the waters, though, when his teacher announces a project on predators, and Shawn is assigned the topic of leopard seals; even worse, his frequent playground victim, Stacy, gets the great white shark. She won’t trade, she can’t be bribed with cookies, and she soon revels in the delicious information that sharks prey on leopard seals. Game on. Stacy the shark now chases Shawn around the playground until he makes the nasty observation that she’s a pretty unimpressive shark if she’s not fast enough to catch a leopard seal. Now Stacy’s in tears, and Shawn needs to refocus on human behavior rather than [End Page 371] the sanguinary law of the wild to make things right. Subisak’s illustrations cleverly capture Shawn’s comic yet problematic overidentification with his favorite predator, portraying him in a shark’s body and putting his long-suffering cat into a fish body when Shawn is in shark mode and a penguin body when the kid is channeling the leopard seal. Not every listener will welcome the shift from Shawn’s comeuppance at the hands of newly empowered Stacy to his readiness to make amends, but Shawn’s classmates will certainly appreciate his redemption. Copyright © 2017 The Board of Trustees of the University of Illinois

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound.

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), Antarctic minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

Calibrating the time span of longitudinal biomarkers in vertebrate tissues when fine‐scale growth records are unavailable

AbstractBiological markers (biomarkers) are invaluable and widely adopted in ecology, archaeology, and anthropology. Serially sampling biomarkers along continuously growing inert tissue, such as vibrissae, hair, nail, horn, or baleen, is an ideal method by which to capture the changes in an individual's diet, environment, climate, health, and stress levels. However, there are complications in calibrating the time periods that samples represent. Here, we assess how the choice of model and the input data used affect the prediction of time span. We use the Antarctic leopard seal, Hydrurga leptonyx, as our model, with stable isotope data from the vibrissae of captive and wild animals. We show that for tissues with nonlinear growth, and where fine‐scale data on tissue growth are unavailable, modeling over the life span of the tissue is a simple and easily adopted approach. In this method, growth parameters are derived from surveys of the study population and the shed–replacement cycle to calibrate the time span of the biomarker data. This model performed better than linear and nonlinear models, which use parameters that have been derived from growth measurements documented over short periods relative to the life span of the tissue. These latter approaches performed in a similar fashion to each other as they tended to overestimate the life span of the tissue. Whether growth is linear or nonlinear, not accounting for position‐specific differences in growth (rates or coefficients) and asymptotic length (L∞) resulted in different interpretations of biomarker data across the samples collected from the same individual. In species where metabolically inert tissue grows in a progressive fashion, the ability to account for time‐specific information refines our ability to interpret the biomarker data. We recommend that this approach be adapted for tissue, such as the vibrissae and hair of mammals and the hair of humans, which exhibit the predictable growth.

Examining the temporal structure and information entropy of leopard seal calling bouts

Leopard seals (Hydrurga leptonyx) produce sequences of stereotyped sounds, or bouts, during their breeding season. The seals share common sounds but combine them in individually distinctive sequences. This study examines the underlying structure of the calling bouts by estimating the information entropy of the sound sequences with three entropy estimators. The independent identically distributed (IID) model estimates entropy from the simple frequencies of each sound. The Markov model estimates entropy from the frequency of pairs of sounds. Finally, the nonparametric sliding window match length (SWML) estimator exploits a relationship between the information entropy and the average subsequence match length. A better model for a given sequence achieves a lower entropy estimate. This study analyzed the calling bouts of 35 leopard seals recorded during the 1992-1994 and 1997-1998 Antarctic field seasons. The decrease of entropy estimates between the IID and Markov models for all seals analyzed confirmed the presence of temporal structures in the bouts. For twenty-one of thirty-five seals, the SWML entropy estimate was not significantly less than the Markov estimate, suggesting that a first-order Markov model accurately represents the structure of their bouts. [Work supported by the Australian-American Fulbright Commission and the Australian Research Council.]

Distribution, density and abundance of Antarctic ice seals off Queen Maud Land and the eastern Weddell Sea

The Antarctic Pack Ice Seal (APIS) Program was initiated in 1994 to estimate the abundance of four species of Antarctic phocids: the crabeater seal Lobodon carcinophaga, Weddell seal Leptonychotes weddellii, Ross seal Ommatophoca rossii and leopard seal Hydrurga leptonyx and to identify ecological relationships and habitat use patterns. The Atlantic sector of the Southern Ocean (the eastern sector of the Weddell Sea) was surveyed by research teams from Germany, Norway and South Africa using a range of aerial methods over five austral summers between 1996–1997 and 2000–2001. We used these observations to model densities of seals in the area, taking into account haul-out probabilities, survey-specific sighting probabilities and covariates derived from satellite-based ice concentrations and bathymetry. These models predicted the total abundance over the area bounded by the surveys (30°W and 10°E). In this sector of the coast, we estimated seal abundances of: 514 (95 % CI 337–886) × 103 crabeater seals, 60.0 (43.2–94.4) × 103 Weddell seals and 13.2 (5.50–39.7) × 103 leopard seals. The crabeater seal densities, approximately 14,000 seals per degree longitude, are similar to estimates obtained by surveys in the Pacific and Indian sectors by other APIS researchers. Very few Ross seals were observed (24 total), leading to a conservative estimate of 830 (119–2894) individuals over the study area. These results provide an important baseline against which to compare future changes in seal distribution and abundance.

Determinación de edades en Otariidae y Phocidae (Carnivora) sobre piezas dentarias, técnicas alternativas

La depositación periódica de capas de esmalte, cemento y dentina en los dientes de los mamíferos es de gran utilidad para la determinación de edades absolutas. Los diferentes sucesos que se producen durante la vida del animal como la muda, la madurez sexual, período de lactancia y de alimentación, se reflejan muchas veces en la cantidad y tipo de depósito de dentina en las piezas dentarias. Los objetivos de este trabajo son: determinar, con diferentes técnicas aplicables sobre dientes, las edades absolutas de ejemplares de Phocidae y Otariidae (Mammalia) alojados en diferentes colecciones de la Argentina; comparar los resultados obtenidos con el empleo de las distintas técnicas; y añadir un dato relevante a cada ejemplar estudiado. Se compararon, ajustaron, y aplicaron las técnicas a un total de 335 ejemplares de las siguientes especies: Arctocephalus gazella, Arctocephalus australis, Otaria byronia, Mirounga leonina, Leptonychotes weddellii, Lobodon carcinophagus, e Hydrurga leptonyx. Las tecnicas aplicadas fueron: el conteo de anillos externos de la raíz, el conteo de líneas de dentina y de cemento tanto sin descalcificar como descalcificado. Los resultados mostraron que no todas las técnicas son aplicables a todas las especies, ni para todas las piezas dentarias, dependiendo en parte del tamaño de las piezas y de la forma en que el cemento se deposita. Finalmente recomendamos cuáles técnicas son más efectivas para cada especie estudiada. La técnica de conteo de anillos externos y lineas de dentina con y sin descalcificación es conveniente para los Arctocephalus, mientras que la del conteo de líneas de dentina por descalcificación es recomendable para O. byronia, en los fócidos se recomienda el conteo de líneas de cemento con previa descalcificación en poscaninos.

Births of leopard seals Hydrurga leptonyx in southern Chile

Leopard seals (Hydrurga leptonyx) are widely distributed within the Antarctic pack ice. Recently they have been reported further north, in the fjords of southern Chile, where individuals remain year-round, especially on Tierra del Fuego Island. Little is known of the leopard seals reproductive biology or breeding distribution, and more specifically, whether they use southern Chilean water to breed. Two recent opportunistic sightings of leopard seal adult–pup pairs were observed in Parry Fjord, Almirantazgo Sound, on 2 December 2012 and 6 October 2015. These are the first documented recordings of leopard seal pups in southern South America and the second and third records of leopard seal pups on the continents north of the Polar Front. Although the pups reported here were dead, these observations are important because they add new evidence that leopard seals pup asynchronously, unlike other ice-breeding seals. It provides further information regarding the leopard seals use of South American waters.

Summer diving and haul‐out behavior of leopard seals (Hydrurga leptonyx) near mesopredator breeding colonies at Livingston Island, Antarctic Peninsula

AbstractLeopard seals are conspicuous apex predators in Antarctic coastal ecosystems, yet their foraging ecology is poorly understood. Historically, the ecology of diving vertebrates has been studied using high‐resolution time‐depth records; however, to date such data have not been available for leopard seals. Twenty‐one time‐depth recorders were deployed on seasonally resident adult females in January and February between 2008 and 2014. The average deployment length was 13.65 ± 11.45 d and 40,308 postfilter dives were recorded on 229 foraging trips. Dive durations averaged 2.20 ± 1.23 min. Dives were shallow with 90.1% measuring 30 m or less, and a mean maximum dive depth of 16.60 ± 10.99 m. Four dive types were classified using a k‐means cluster analysis and compared with corresponding animal‐borne video data. Dive activity (number of dives/hour) was concentrated at night, including crepuscular periods. Haul‐out probabilities were highest near midday and were positively correlated with available daylight. Visual observations and comparisons of diving activity between and within years suggest individual‐based differences of foraging effort by time of day. Finally, dive and video data indicate that in addition to at‐surface hunting, benthic searching and facultative scavenging are important foraging strategies for leopard seals near coastal mesopredator breeding colonies.

Vertical fatty acid composition in the blubber of leopard seals and the implications for dietary analysis

The analysis of blubber fatty acids (FAs) is a useful tool to infer diet of mammals that live in remote regions where year-round studies are difficult. The FA may not be distributed uniformly within the blubber, which can have implications for dietary predictive studies. The aim of this study was to determine the FA composition in the blubber core of the Antarctic leopard seal, Hydrurga leptonyx, and evaluate the potential implications of FA stratification for dietary analysis. The blubber cores of 24 seals were sub-sectioned into outer, middle and inner layers and their FA were compared to those of their potential prey species. A vertical variation in FA composition was found across the whole blubber core of the leopard seal. 17 FAs were found at greater than trace amounts (>0.5%) across all samples and the most abundant were: C18:1ω9, C16:1, C22:6ω3, C16:0 and C18:1ω7, which accounted for approximately 70% of the total FA. Almost all FAs had a continuous gradient through the blubber. Principal Component Analysis confirmed separation between inner and outer layers while the middle layer was a transition. The stratification of the leopard seal blubber was similar to the general pattern observed in a variety of marine species: monounsaturated FA (MUFA) dominated the three layers being more abundant in the outer layer, polyunsaturated (PUFA) and saturated FA (SFA) were more abundant in the inner layer. Polyunsaturated FAs are of dietary origin and SFAs are chemically inert so they can be used as a long-term reserve, which suggest that the inner layer is the site of deposition of the FA obtained from diet. The influence of prey on the composition of the leopard seals' blubber was clearer in the inner layer, although neither outer nor inner layers exactly matched the FA of the potential prey. This suggests that there are other components influencing the FA composition of this predator; therefore, in order to carry out dietary analysis it is important to consider the stratification of blubber and to use the inner layer, where the influence of diet is more evident. This has significant implications for sampling methods in the field.

Death age, seasonality, taphonomy and colonization of seal carcasses from Ulu Peninsula, James Ross Island, Antarctic Peninsula

AbstractThe origin and nature of seal carcasses scattered around the Ulu Peninsula, James Ross Island, is examined using robust and novel multidisciplinary analysis. Spatial distribution analysis indicates their predominance at low elevations and on surfaces with negligible slope. The seals died throughout the last century. Dental cement increments indicate that the seals died in late winter, and we interpret this to show an influence of the persistence and break-up of sea ice and the appearance of pools/cracks in the northern Prince Gustav Channel on death. Specifically, after being trapped by a late winter freeze-up the seals search for open water, become disoriented by snow-covered flat valleys and move inland. Carcasses from all age groups of crabeater seal are found on land, but inland movement is less notable for Weddell and leopard seals. Although most carcasses appear to have remained unchanged during the last 10 years due to the cold and dry conditions, a few carcasses that are located in sites of snow accumulation and subsequent melting have undergone enhanced decay. Decaying seal carcasses represent loci of nutrient release in a nutrient deficient environment and are colonized by algae, cyanobacteria, lichens and mosses. This research suggests further useful studies for the future.

Novel foraging strategies observed in a growing leopard seal (Hydrurga leptonyx) population at Livingston Island, Antarctic Peninsula

Leopard seals are apex predators that can alter the community structure of Antarctic coastal ecosystems. Previous behavioral studies were limited to land-based, daytime observations of foraging leopard seals. Consequently, foraging tactics, social behaviors, and indirect ecosystem impacts are poorly understood. Here, we present the first analysis of animal-borne HD video footage for foraging leopard seals. Each CRITTERCAM was deployed with Fastloc GPS and time-depth recorder instruments providing fine-scale habitat context for observed foraging behavior. We analyzed seven deployments obtained in January and February of 2013 and 2014 from adult female leopard seals near mesopredator breeding colonies on Livingston Island, Antarctica. The average deployment length was 4.80 ± 2.45 (range 0.86–9.12) days, which covered a total of 16 foraging trips. Habitat use, along with 39 prey capture attempts, and 11 leopard seal social encounters were scored from 50.3 h of video data. We obtained 3,833 post-filter GPS positions, accurate to within 70 m, and the mean dive depth was 14.84 ± 8.98 m. Leopard seal foraging focused on four prey items: Antarctic fur seals, Antarctic fur seal pups, pygoscelid penguins, and demersal notothen fishes. Ambush tactics used only by a subset of leopard seals drove high capture success rates of fur seal pups. We identified novel prey-specific foraging tactics including stalking and flushing notothen fishes. Leopard seals have been described as generalist apex predators; however, video and movement data suggest that leopard seals employ specialized prey-specific hunting tactics. Although preliminary, our findings indicate that leopard seals can affect coastal ecosystems through pathways beyond direct predation, including intraspecific kleptoparasitism and facultative scavenging/food caching. Our results suggest that position-integrated video data will be vital in quantifying the ecological impact of this abundant and versatile apex predator.

Novel foraging strategies observed in a growing leopard seal (Hydrurga leptonyx) population at Livingston Island, Antarctic Peninsula

Leopard seals are apex predators that can alter the community structure of Antarctic coastal ecosystems. Previous behavioral studies were limited to land-based, daytime observations of foraging leopard seals. Consequently, foraging tactics, social behaviors, and indirect ecosystem impacts are poorly understood. Here, we present the first analysis of animal-borne HD video footage for foraging leopard seals. Each CRITTERCAM was deployed with Fastloc GPS and time-depth recorder instruments providing fine-scale habitat context for observed foraging behavior. We analyzed seven deployments obtained in January and February of 2013 and 2014 from adult female leopard seals near mesopredator breeding colonies on Livingston Island, Antarctica. The average deployment length was 4.80 ± 2.45 (range 0.86–9.12) days, which covered a total of 16 foraging trips. Habitat use, along with 39 prey capture attempts, and 11 leopard seal social encounters were scored from 50.3 h of video data. We obtained 3,833 post-filter GPS positions, accurate to within 70 m, and the mean dive depth was 14.84 ± 8.98 m. Leopard seal foraging focused on four prey items: Antarctic fur seals, Antarctic fur seal pups, pygoscelid penguins, and demersal notothen fishes. Ambush tactics used only by a subset of leopard seals drove high capture success rates of fur seal pups. We identified novel prey-specific foraging tactics including stalking and flushing notothen fishes. Leopard seals have been described as generalist apex predators; however, video and movement data suggest that leopard seals employ specialized prey-specific hunting tactics. Although preliminary, our findings indicate that leopard seals can affect coastal ecosystems through pathways beyond direct predation, including intraspecific kleptoparasitism and facultative scavenging/food caching. Our results suggest that position-integrated video data will be vital in quantifying the ecological impact of this abundant and versatile apex predator.

Spatial patterns in activity of leopard seals Hydrurga leptonyx in relation to sea ice

Spatial patterns in activity of leopard seals Hydrurga leptonyx in relation to sea ice

A small unmanned aerial system for estimating abundance and size of Antarctic predators

Quantifying the distribution and abundance of predators is integral to many ecological studies, but can be difficult in remote settings such as Antarctica. Recent advances in the development of unmanned aerial systems (UAS), particularly vertical takeoff and landing (VTOL) aircraft, have provided a new tool for studying the distribution and abundance of predator populations. We detail our experience and testing in selecting a VTOL platform for use in remote, windy, perennially overcast settings, where acquiring cloud-free high-resolution satellite images is often impractical. We present results from the first use of VTOLs for estimating abundance, colony area, and density of krill-dependent predators in Antarctica, based upon 65 missions flown in 2010/2011 (n = 28) and 2012/2013 (n = 37). We address concerns over UAS sound affecting wildlife by comparing VTOL-generated noise to ambient and penguin-generated sound. We also report on the utility of VTOLs for missions other than abundance and distribution, namely to estimate size of individual leopard seals. Several characteristics of small, battery-powered VTOLs make them particularly useful in wildlife applications: (1) portability, (2) stability in flight, (3) limited launch area requirements, (4) safety, and (5) limited sound when compared to fixed-wing and internal combustion engine aircraft. We conclude that of the numerous UAS available, electric VTOLs are among the most promising for ecological applications.

Preliminary phylogenetics and biogeographic history of the Pliocene seal, Homiphoca capensis from Langebaanweg, South Africa

A phylogenetic analysis of the Langebaanweg seals was undertaken to better understand their relationships. The fossil phocid seals from Langebaanweg nest within the Lobodontini and form a clade that includes Ommatophoca rossii (Ross seal). The Langebaanweg seals' relationships are unresolved in both analyses. Two analyses were performed producing differing results. The prior weights analysis produced a clade that included the Ross seal (Ommatophoca rossii) + the Langebaanweg seals + the remaining Antarctic lobodontines. The implied weights analysis (k=3) produced a clade including the South American seals (Hadrokirus and Piscophoca) + the Ross seal (Ommatophoca rossii) + the Langebaanweg seals, which is part of the polytomy that includes the clade including the leopard seal (Hydrurga leptonyx) and the crabeater seal (Lobodon carcinophaga) and Acrophoca longirostis. In both analyses the monophyletic group LBW-F + LBW-D + LBW-A is retained while the monophyletic group LBW-C + LBW-B from the first analysis is replaced by the polytomy LBW-B + LBW-C + LBW-E in the second. The collapse of the monophyletic group LBW-C + LBW-B is due to its poor support (20), most likely as a result of LBW-C being incomplete caudally. Island hopping is proposed as a means for phocid seal migration to South Africa. The presence of islands along South Africa's west coast and phocid seal adaptation to a life independent of land and the use of ice as haul out sites lend support to this theory. During the Pleistocene, the decrease in local sea levels resulted in the loss of islands which may have resulted in the extinction of these seals over time.

Marine mammals of Easter Island (Rapa Nui) and Salas y Gomez Island (Motu Motiro Hiva), Chile: a review and new records

The Chilean oceanic islands Easter Island (Rapa Nui) and Salas y Gomez Island (Motu Motiro Hiva) have received little attention with regards to basic marine mammal investigations. Here we review and update available information on the status of marine mammals in this area from different sources, including published accounts, local interviews and two recent expeditions. We also provide detailed accounts for each confirmed family or species, including historical data from published archaeological studies and whalers' logbooks from the 18 th to the 20 th centuries. Results indicate that a total of five marine mammal families (Balaenopteridae, Physeteridae, Ziphiidae, Delphinidae and Phocidae) have been confirmed within the study area, representing two mammalian orders (Cetartiodactyla and Carnivora). Within these, twelve species are known to occur: blue whale (Balaenoptera musculus), unidentified minke whale (Balaenoptera bonaerensis or B. acutorostrata), humpback whale (Megaptera novaeangliae), sperm whale (Physeter macrocephalus), Cuvier's beaked whale (Ziphius cavirostris), Blainville's beaked whale (Mesoplodon densirostris), false killer whale (Pseudorca crassidens), unidentified pilot whale (Globicephala sp.), bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus sp.), southern elephant seal (Mirounga leonina) and leopard seal (Hydrurga leptonyx). We discuss the implications of some of most noteworthy records and make a plea for further studies to improve our knowledge of these top predators in one of the most isolated places in the world.