Southern Elephant Seal Research Articles

First record of a southern elephant seal (Mirounga leonina) in Sri Lankan waters

An unusual sighting of a juvenile southern elephant seal (Mirounga leonina), outside its typical range, was recorded off the southern coast of Sri Lanka between 20th November and 20th December 2019. The individual, a male as confirmed by the presence of a prepuce, underwent a catastrophic moult during this 1 month period, following which no further observations were recorded and so it was assumed it returned to sea. This represents the first confirmed sighting of a southern elephant seal, and indeed a phocid, in Sri Lankan waters.

Inter- and intrasex habitat partitioning in the highly dimorphic southern elephant seal.

Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf (~2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size (~2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade‐off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade‐off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea‐ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure.

Southern elephant seal Mirounga leonina molting at Mauritius Island

Southern elephant seal Mirounga leonina molting at Mauritius Island

Design of Deployment Strategies to Monitor the Movement of Animals with Passive Electronic Devices.

Current animal monitoring systems have improved our knowledge of quantitative animal ecology. There are many electronic tracking technologies such as VHF/UHF telemetry, light-level geolocation, ARGOS satellite telemetry and GPS tracking. To reach the desired level of information retrieval requires the planning of adequate equipment effort and coverage, which depends on the properties of the system. We propose an equipment arrangement model consisting of a given number of receiver stations in a two-dimensional space in which the animals move according to a central place movement model. The objective is to characterize how the transmission of tracking data depends on the movement of the animals and the design of the equipment deployment: quantity and location of the receiver stations and their associated reception radius. We also implement the model using real trajectories of southern elephant seals and Australian sea lions publicly available online and tracked during the years 2010–2012. We characterize the data transmission based on different equipment configurations and we obtained analogous results to the theoretical model.

Conditions influencing the appearance of thermal windows and the distribution of surface temperature in hauled-out southern elephant seals.

Pinnipeds (true seals, sea lions and walruses) inhabit two thermally different environments, air and water, so need to make continuous adjustments to maintain a balanced body temperature. The thermal isolation properties of thick blubber keep warmth within the body's core, ideal for mammals while in the water; however, when on land, this thick blubber makes it difficult to lose heat. Some pinnipeds use thermal windows, discrete patches where temperature changes on their body surface, as a mechanism to dissipate excessive heat. We identify the factors that correlate with the appearance of thermal windows and changes in body surface temperature on southern elephant seals, Mirounga leonina, while they are hauled out ashore. Infrared thermography was used to measure surface temperature of the seals. Temperature was lower on the torso than the flippers and head, suggesting that not all body sites have the same role in thermal balance. Air temperature was the main driver of variation in the surface temperature of the seals' flippers and head; seals cool their superficial tissues when the air temperature is below ~ 2°C. This minimizes heat loss by reducing the thermal gradient between their skin and the ambient air. Wind speed was the main predictor of whether thermal windows appear on a seals' body surface. When wind speed was minimal, thermal windows occurred more often, which may be associated with either hair and skin drying, or producing thermal conditions for hair and skin regrowth. The type of aggregation (huddled or alone) influenced the surface temperature of the fore flippers; however, we did not find statistical influence of the seal's sex, state of moult, or the substrate on which they were hauled out (kelp or sand). Understanding how animals maintain their thermal balance is important if we are to predict how they will respond to future climate change.

Mawson’s views on use of natural resources in the Antarctic and sub-Antarctic

Abstract Sir Douglas Mawson is a well-known Antarctic explorer and scientist. Early in his career, he recognised opportunities for commerce in Antarctic and sub-Antarctic regions. While at Cape Denison, Antarctica, in 1913 on the Australasian Antarctic Expedition (AAE), the Adelie Blizzard magazine was produced. Mawson contributed articles about Antarctic natural resources and their possible use. Later, he advocated Australia be involved in pelagic whaling. He collected seal skins and oil for their commercial value to be assessed by the Hudson’s Bay Company. During the AAE, Mawson visited Macquarie Island where an oiling gang was killing southern elephant seals and royal penguins. Mawson was concerned that they were over-exploited and lobbied successfully to stop the killing. His plans for Macquarie Island included a wildlife sanctuary, with a party to supervise access, send meteorological observations to Australia and New Zealand, and be self-funded by harvesting elephant seals and penguins. Macquarie Island was declared a sanctuary in 1933. Although Mawson has been recognised as an early proponent of conservation, his views on conservation of living natural resources were inconsistent. They should be placed in their historical context: in the early twentieth century, utilisation of living natural resources was viewed more favourably than currently.

Validating the use of bulk tissue stable isotope and amino acid δ15N values measured in molted hair and epidermis of elephant seals to assess temporal foraging niche specialization

The degree of dietary generalization versus specialization exhibited by populations can impact their ability to respond to changing environmental conditions. Naturally shed hair and epidermis are easily collected and may provide a suitable substrate for stable isotope analysis to assess trophic niche specialization. Whether fasting influences the isotopic composition of molted tissues has not been assessed. Here, we gauged the validity of using carbon (δ13C) and nitrogen (δ15N) isotope analysis of molted hair and the outermost epidermis as proxies to study the foraging ecology of southern elephant seals Mirounga leonina at Marion Island in the southern Indian Ocean. Similarity in both bulk tissue (δ13C and δ15N) and amino acid (δ15N) isotope values of molted tissues and whiskers known to reflect fasting confirmed that physiological changes associated with fasting influenced hair and epidermis isotope values. We recommend caution when using the isotopic composition of molted hair and epidermis to make ecological inferences regarding diet and/or movement. Despite these limitations, molted hair can be used to detect extreme foraging behaviors, which we show using an extensive data set of hair sampled from marked individuals (n = 331) that hauled out on Marion Island during the 2012-2013 annual pelage molt. Other factors, such as ontogenetic shifts in diet and potential environmental (baseline) isotopic variation, also influence hair δ13C and δ15N values, which complicates the use of isotopic data from molted tissues to assess the temporal consistency of an individuals’ isotopic niche.

Serological screening for Brucella spp. and Leptospira spp. antibodies in southern elephant seals Mirounga leonina from Elephant Island, Antarctica, in 2003 and 2004.

Brucella spp. and Leptospira spp. antibodies were surveyed in 35 southern elephant seals (SESs) Mirounga leonina at Elephant Island (South Shetland Islands), western Antarctic peninsula, in the Austral summer of 2003 and 2004. The rose Bengal test and a commercial competitive ELISA (c-ELISA) were used to detect Brucella spp. exposure, and the microscopic agglutination test (MAT) with 22 live serovars was used to determine anti-Leptospira spp. antibodies. We found evidence of Brucella spp. exposure in 3 of 35 (8.6%) SESs tested via the c-ELISA displaying high percentage inhibition (PI), similar to other studies in pinnipeds in which Brucella spp. antibodies have been determined. Two of the 3 positives were pups (PI = 70.4 and 86.6%), while the third was an adult female (PI = 48.8%). The 3 c-ELISA positive SESs were additionally tested via the serum agglutination test but were found to be negative. All individuals were negative for antibodies against 22 Leptospira spp. serovars by MAT. These results contribute to the knowledge and monitoring of zoonotic pathogens with epizootic potential in Southern Ocean pinnipeds. Given the potential impact that pathogens may have on the abundance of wild (sometimes threatened and endangered) populations, constant monitoring and surveillance are required to prevent pathogen spread, particularly under forecast climate change scenarios.

Pathogen surveillance in Southern Ocean pinnipeds

Knowledge of the health status and potential effect of disease outbreaks among Southern Ocean fauna may be decisive for its conservation. We assessed the exposure and infection of Antarctic fur seals (Arctocephalus gazella, AFS) and Southern elephant seals (Mirounga leonine, SES) to parapoxvirus, Phocid alphaherpesvirus-1 (PhHV-1), smooth Brucella spp. and Toxoplasma gondii. AFS (n = 65) serum and swab samples, and SES (n = 13) serum samples from the sub--Antarctic island of Bouvetøya (54°25’S, 03°22’E) were collected during two austral summers (2014/15, 2017/18). Three polymerase chain reaction (PCR) tests amplifying the DNA polymerase, B2L and GIF parapoxvirus genomic regions were performed, investigating DNA from mucosal swab samples. The glycoprotein B gene was targeted to detect PhHV-1 viral DNA. Sera were assayed for T. gondii and smooth Brucella spp. antibodies with indirect enzyme-linked immunosorbent assays. Parapoxvirus PCR amplicons of the expected size were generated in two of the 29 AFS pups (nasal swabs, 2014/15), targeting the B2L (n = 2) and DNA polymerase (n = 1) genes, whereas the GIF PCR did not amplify target sequences. The PCR amplicons were sequenced and blasted in GenBank, revealing highest similarity with a seal parapoxvirus, confirming the presence of the virus in AFS for the first time. No PhHV-1 amplicons were generated, and antibodies against T. gondii or smooth Brucella spp. were not detected. Our data indicate that these seals are host for parapoxvirus but are neither exposed to smooth Brucella spp. nor T. gondii. Evidence of PhHV-1 shedding was not detected.

Remotely Piloted Aircraft System (RPAS)-Based Wildlife Detection: A Review and Case Studies in Maritime Antarctica.

Simple SummaryRemotely piloted aircraft systems (RPAS) have been successfully applied in wildlife monitoring with imaging sensors to improve or to supplement conventional field observations. To effectively utilize this technique, we reviewed previous studies related to wildlife detection with RPAS. First, this study provides an overview of the applications of RPAS for wild animal studies from the perspective of individual detection and population surveys as well as behavioral studies. In terms of the RPAS payload, applying thermal-imaging sensors was determined to be advantageous in detecting homeothermic animals due to the thermal contrast with background habitat using case studies detecting southern elephant seal (Mirounga leonina) using RGB and thermal imaging sensors in King George Island, maritime Antarctica.In wildlife biology, it is important to conduct efficient observations and quantitative monitoring of wild animals. Conventional wildlife monitoring mainly relies on direct field observations by the naked eyes or through binoculars, on-site image acquisition at fixed spots, and sampling or capturing under severe areal constraints. Recently, remotely piloted aircraft systems (RPAS), also called drones or unmanned aerial vehicles (UAV), were successfully applied to detect wildlife with imaging sensors, such as RGB and thermal-imaging sensors, with superior detection capabilities to those of human observation. Here, we review studies with RPAS which has been increasingly used in wildlife detection and explain how an RPAS-based high-resolution RGB image can be applied to wild animal studies from the perspective of individual detection and population surveys as well as behavioral studies. The applicability of thermal-imaging sensors was also assessed with further information extractable from image analyses. In addition, RPAS-based case studies of acquisition of high-resolution RGB images for the purpose of detecting southern elephant seals (Mirounga leonina) and shape property extraction using thermal-imaging sensor in King George Island, maritime Antarctica is presented as applications in an extreme environment. The case studies suggest that currently available cost-effective small-sized RPAS, which are capable of flexible operation and mounting miniaturized imaging sensors, and are easily maneuverable even from an inflatable boat, can be an effective and supportive technique for both the visual interpretation and quantitative analysis of wild animals in low-accessible extreme or maritime environments.

Ontogenetic niche partitioning in southern elephant seals from Argentine Patagonia

AbstractElephant seals, Mirounga spp., are highly dimorphic, having different energetic requirements according to age and sex, and foraging in various ecological and oceanographic contexts. Resource partitioning has been shown for the sub‐Antarctic populations of southern elephant seals, M. leonina, where colonies are surrounded by narrow shelves that deepen abruptly. In contrast, seals from Península Valdés (Argentina), in the northernmost extent of the breeding range, face an extended, shallow, temperate, and productive continental shelf. We integrated tracking data from 98 animals (juveniles and adults, males and females) gathered over more than two decades, and found that although all available habitats were used, individuals segregated by age and sex. Juvenile males favored shelf habitats, whereas subadult and adult males also used the shelf break. Juvenile females preferred the shelf and the more distant Argentine Basin used by postbreeding and postmolt adult females. Males showed the highest proportion of area‐restricted search locations, suggesting more spatially concentrated feeding activity, and likely reflecting a preference for foraging habitat and prey. Our results are consistent with those from other populations, implying that elephant seals show remarkable similarities in habitat use by age and sex classes, despite broad differences in the offshore habitats between sub‐Antarctic and temperate ecosystems.

Distinct gut microbiotas between southern elephant seals and Weddell seals of Antarctica.

The gut microbiome provides ecological information about host animals, but we still have limited knowledge of the gut microbiome, particularly for animals inhabiting remote locations, such as Antarctica. Here, we compared fecal microbiota between southern elephant seals (Mirounga leonina) and Weddell seals (Leptonychotes weddelli), that are top predatory marine mammals in the Antarctic ecosystem, using 16S rRNA amplicon sequencing and assessed the relationships of the gut microbial communities to functional profiles using gut metabolite analysis. The bacterial community did not differ significantly by host species or sex at the phylum level, but the distinction at the family level was obvious. The family Ruminococcaceae (Firmicutes) was more abundant in southern elephant seals than in Weddell seals, and the families Acidaminococcaceae (Firmicutes) and Pasteurellaceae (Gammaproteobacteria) were uniquely present in Weddell seals. The fecal bacterial community structure was distinctively clustered by host species, with only 6.7% of amplicon sequence variants (ASVs) shared between host species. This result implies that host phylogeny rather than other factors, such as diet or age, could be the major driver of fecal microbiotic diversification. Interestingly, there was no apparent sex effect on bacterial community structure in Weddell seals, but the effect of sex was pronounced in adult southern elephant seals mainly due to the prevalence of Edwardsiella sp., suggesting that extreme sexual dimorphism may modulate the gut microbiota of southern elephant seals. Unlike the clear distinction in the taxonomic composition of fecal bacterial communities, there were no discernible differences in the profiles of potential microbial functions and gut metabolites between host species or sexes, indicating that functional redundancy dominates the gut microbiota of seals surveyed in this study.

The northernmost haulout site of South American sea lions and fur seals in the western South Atlantic

We present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months.

Correction: Fudala, K. and Bialik, R.J. Breeding Colony Dynamics of Southern Elephant Seals at Patelnia Point, King George Island, Antarctica. Remote Sensing 2020, 12, 2964

The authors wish to make the following correction to this paper [...]

Characterization of an alphavirus isolated from a stranded harbor porpoise (Phocoena phocoena) from Alaska

The family Togaviridae comprises several significant human and veterinary mosquito-borne pathogens. Two togaviruses (genus Alphavirus) have been previously identified in association with marine mammals, the southern elephant seal virus (SESV) and Eastern equine encephalitis virus (EEEV) from a fatal captive harbor seal infection. Herein we report the ultrastructural and phylogenomic characterization of a novel marine togavirus, the first isolated from a cetacean, an Alaskan harbor porpoise (Phocoena phocoena) displaying ulcerative dermatitis. A skin sample was processed for virus isolation on Vero.DogSLAMtag cells and cytopathic effects (CPE) were observed on primary isolation approximately 20 days post-infection. Transmission electron microscopy of the infected Vero.DogSLAMtag cells revealed typical alphavirus particles budding from both plasma and vacuolar membranes of infected cells. A next-generation sequencing approach was used to determine the near complete genome of the Alaskan harbor porpoise alphavirus (AHPV). Phylogenetic analysis supported the AHPV as the sister species to the SESV, forming a marine mammal alphavirus clade separate from the recognized alphavirus antigenic complexes. Genetic comparison of the protein coding sequence of the AHPV to other alphaviruses demonstrated amino acid identities ranging from 42.1-67.1%, with the highest identity to the SESV. Based on its genetic divergence, we propose the AHPV represents a novel alphavirus species, pending formal proposal to and ratification by the International Committee on Taxonomy of Viruses. The ecological and genetic characteristics of the AHPV and the SESV also suggest they represent a novel antigenic complex within the genus Alphavirus, which we propose to be named the Marine Mammal Virus Complex. The role of the AHPV in the associated harbor porpoise cutaneous pathology, if any, remains unclear. Further research is needed to determine AHPV’s route(s) of transmission and potential vectors, host range, prevalence, and pathogenicity in cetaceans including harbour porpoises.

Algoritmos Avanzados de Adquisición y Procesamiento de Nubes de Puntos 3D para el Descubrimiento de Información en Mamíferos Marinos

El Procesamiento de imágenes es una de las ramas de la informática de mayor crecimiento en los últimos tiempos. Esto no solo se debe a la amplitud de sus aplicaciones, sino también a que el avance de la tecnología que se viene experimentando en estos años, junto con el surgimiento de herramientas para un rápidoaprovechamiento de las mismas, ha hecho posible que algoritmos cuyos costos de procesamiento eran muy altos hasta hace unos años atrás, puedan ahora ser ejecutados en períodos de tiempo relativamente cortos.Por otro lado, el abaratamiento de costos en elementos relacionados a la captura de información visual ha incentivado enormemente la realización de estudios afines a su aplicación fuera del ámbito industrial. En este contexto, los sensores de profundidad han abierto un nuevo campo de estudio permitiendo generar y trabajar con modelos tridimensionales de elementos del mundo real tal y como son en lugar de los modelos prediseñados.En el caso particular de la biología, se ha abierto una posibilidad de mejorar la manera en que los científicos obtienen información relevante a sus investigaciones, siendo este el caso del estudio de mamíferos marinos, más concretamente el Elefante Marino del Sur (Mirounga leonina).En particular este trabajo se enfoca en la búsqueda de algoritmos apropiados para la limpieza y análisis automatizado de modelos tridimensionales (nubes de puntos) de elefantes marinos. Dicho estudio brindaría a los científicos un método no invasivo para obtener medidas mucho mas rápidas y precisas que las proporcionadas por los métodos utilizados hasta el momento, a la vez que reduciría de manera considerable los riesgos (tanto para los científicos como para los animales) que estos conllevan.

Inferring Variation in Southern Elephant Seal At-Sea Mortality by Modelling Tag Failure

Identifying factors influencing survivorship is key to understanding population persistence. Although satellite telemetry is a powerful tool for studying remote animal ecology and behaviour it is rarely used for demographic studies because distinguishing the death of the animal (individual mortality) from failure of the tag (mechanical tag failure) has proven difficult. Southern elephant seals present an opportunity to separate tag failure from animal mortality thanks to the availability of large tracking datasets, broad knowledge of demographic rates, and because for these large animals, satellite tags are known not to influence mortality rates. A key rationale for investigating satellite telemetry to estimate mortality as compared to using traditional Capture-Mark-Recapture methods is the potential for obtaining spatially and temporally specific information, particularly while the animals are at sea and largely unobservable. We used satellite tag data from 182 seals from Isles Kerguelen, deployed between 2004 and 2018. Of these, 76 (42%) tags transmitted for the full post-moult foraging trip (max. 265 days for females and max. 305 days for sub-adult males) with the remaining 107 tags (58%) ceasing transmission at sea. We found that contrary to expectations, behavioural choices seem not to influence tag failure rates by mechanical means, rather the signals we detected seemed to align with previously described variation in mortality between groups. There was evidence, albeit limited, for an increase in tag failure for adult females in years with negative Southern Annular Mode (lower Southern Ocean productivity). We speculate that this increase in failure may suggest higher mortality in these years. Also, males using the Kerguelen Plateau had higher tag failure rates than those in the sea-ice zone, perhaps indicative of higher mortality. We suspect that these differences in tag failure rates between groups reflect variation in predator exposure and foraging success. This suggests satellite telemetry could be used to infer mortality events for southern elephant seals while they are at sea.

Diving Behavior of Mirounga leonina: A Functional Data Analysis Approach

The diving behavior of southern elephant seals, Mirounga leonina, is investigated through the analysis of time-depth dive profiles. The originality of this work is to consider dive profiles as continuous curves. For this purpose, a Functional Data Analysis (FDA) approach is proposed for the shape analysis of a collection of dive profiles. Complexity of dive shapes is characterized by a mixture of three main shape variations accounting for about $80\%$ of the entire variability: U or V shape, vertical depth variability during the bottom time, and skewed left or right. Model-based clustering allows the identification of eight dive shape clusters in a quick and automated way. Connection between shape patterns and classical descriptors, as well as the number of prey capture events, is achieved, showing that the clusters are coherent to specific foraging behaviors previously identified in the literature labeled as drift, exploratory and active dives. Finally, FDA is compared to classical methods relying on the computation of discrete dive descriptors. Results show that taking the shape of the dive as a whole is more resilient to corrupted or incomplete sampled data. FDA is, therefore, an efficient tool adapted for processing and comparing dive data with different sampling frequencies and for improving the quality and the accuracy of transmitted data.

Breeding Colony Dynamics of Southern Elephant Seals at Patelnia Point, King George Island, Antarctica

During the 2019 breeding season (October-December), a battery-powered DIJ Inspire 2 drone was used to investigate a breeding southern elephant seal colony located at Patelnia Point (ASPA 128, King George Island, South Shetland Islands, maritime Antarctica). Twelve unmanned aerial vehicle (UAV) missions conducted 50–70 m above ground level (AGL) were completed to monitor the breeding ground with a maximum of 0.348 km2. The missions were planned in Pix4D Capture software. A drone, with the support of ground cameras and observations, was used to derive population counts, map harems, and track the phenology of the southern elephant seals. Based on data obtained from the UAV missions, orthophotomaps were created in PIX4D Mapper and then analyzed in QGIS. Calculated values of body size parameters such as body length and orthogonal body surface area were used to determine the age and sex of individuals. Analysis of the ranges of the harems on particular days, supported by an analysis of land conditions that generate physical barriers to the movement of animals, allowed zones in which the transformations of groups of harems took place to be determined. The hypothesized hermeticity of the designated zones was supported by statistical tests. The use of drones allows for comprehensive population analyses of the breeding colonies of elephant seals such as censuses of pups and adult individuals, determination of the sex ratio, and spatial analysis of the distribution of breeding formations. In addition, it allows for a more accurate result than ground counting.

Extreme dispersal or human-transport? The enigmatic case of an extralimital freshwater occurrence of a Southern elephant seal from Indiana.

Elephant seals (Mirounga spp.) are the largest living pinnipeds, and the spatial scales of their ecology, with dives over 1 km in depth and foraging trips over 10,000 km long, are unrivalled by their near relatives. Here we report the discovery of an incomplete Holocene age Southern elephant seal (M. leonina) rostrum from Indiana, USA. The surviving material are two casts of the original specimen, which was collected in a construction excavation close to the Wabash River near Lafayette, Indiana. The original specimen was mostly destroyed for radiometric dating analyses in the 1970s, which resulted in an age of 1,260 ± 90 years before the present. The existence of sediments in the original specimen suggests some type of post depositional fluvial transportation. The prevalent evidence suggests that this male Southern elephant seal crossed the equator and the Gulf of Mexico, and then entered the Mississippi River system, stranding far upriver in Indiana or adjacent areas, similar to other reported examples of lost marine mammals in freshwater systems. Based on potential cut marks, we cannot exclude human-mediated transportation or scavenging by Indigenous peoples as a contributing factor of this occurrence. The material reported here represents by far the northernmost occurrence of a Southern elephant seal in the Northern Hemisphere ever recorded. The unusual occurrence of a top marine predator >1,000 km from the closest marine effluent as a potential extreme case of dispersal emphasizes how marine invasions of freshwater systems have happened frequently through historical (and likely geological) time.