Expedition news: MIMMP tag seals on pristine Prince Edward Island!

In November 2023, 13 scientists landed on sub-Antarctic Prince Edward Island, becoming the first visitors to this pristine island in 12 years. Prince Edward lies approximately 20km from its more well-known neighbour, Marion Island. Although smaller, Prince Edward is more pristine than Marion, largely due to its strict management plan which only enables a small group of visitors for short visits (max of 8 days) every five years.

The rugged coastline of Prince Edward Island. Photo: Rowan Jordaan

Camp near Cave Bay. Photo: Rowan Jordaan

Part of this team, were 2x MIMMP sealers and research associates, Dr Chris Oosthuizen and Dr Rowan Jordaan. Their goal for the expedition was to tag all the recently weaned southern elephant seal pups. This expedition conveniently took place shortly after the conclusion of the annual elephant seal breeding season, the timing was therefore perfect for this activity. The only previous occasion where elephant seal pups were tagged on Prince Edward was in 2004 but because that expedition took part in December, many pups had already departed the island on that occasion and the extent of the breeding population on Prince Edward could not be robustly determined.

Chris (left) and Rowan (right) standing above McNish Bay with Marion Island in the distance. Photo: Chris Oosthuizen

Recently tagged elephant seal pups with their Prince Edward PEBZ tags. Photo: Rowan Jordaan

Not quite knowing what to expect, Chris and Rowan set off with a full set of tags (specially made for Prince Edward Island) and applicators in hand. The rugged coastline was generally not well suited to elephant seals but where there was a favourable beach, elephant seal weaners were in abundance! Chris and Rowan spent the days walking along the coastline until they came across these beaches and then they spent a lot of time finding and tagging all the pups in attendance. Tagging was often interrupted by killer whales who also spent time at the beaches, hoping to catch an unsuspecting weaner in the shallows. The beach with the largest number of weaners, Boggel beach, was situated at the base of a scoria cone and its long, black sandy beach was peppered with elephant seal weaners and a couple of very calm adult males. At the end of several days of tagging, 131 weaners were tagged on this beach alone! What a site this beach would be in peak breeding season!

A group of weaners on Boggel Beach, a volcanic sand beach at the base of a scoria cone. Photo: Rowan Jordaan

The everpresent killer whales patrolling the shallows at busy beaches. Photo: Rowan Jordaan

McNish Bay on the south western corner of Prince Edward was arguably one of the more scenic beaches on the island (and possibly in the archipelago). Surrounded by colossal cliffs, coloured in various shades of reds and browns, this beach faced Marion Island, which could be seen in the distance. It was a warm summers day and after tagging 34 pups on McNish Bay beach, Chris and Rowan had to seek shade in an old sealer shelter where they enjoyed lunch before the long walk back to camp. The weather that day was particularly pleasant and the weather in general always seemed better during the day than at night. This made the days spent walking and tagging more enjoyable compared to the sleepless nights endured in the tents back at camp. We now understand why visitors can only spend a max of 8 days on the island, there aren’t many tents that could survive the wind for much longer!

Chris checks an adult male elephant seal for tags at Cave Bay beach. Photo: Rowan Jordaan

The expedition lasted 7 nights before the team was pulled off the island due to (more) severe weather en route. In total, 412 elephant seal weaners were present on Prince Edward, the majority of which were tagged. This tagging event provides us with valuable information on the size of the elephant seal breeding population on Prince Edward and movement to and from our main study site, Marion Island. All killer whales seen during this expedition have also been seen at Marion. In addition to the weaners, some resting bulls and a few late breeding females, a few non-breeding yearling and sub adults were also noted on the beaches and it was refreshing to see some of these animals carrying tags that they received on Marion Island. We look forward to seeing how many of these seals carrying PEBZ tags are seen on Marion as part of our continuous monitoring taking place there!

Field Assistant Vacancies 2024-25 for MIMMP - CLOSED

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2024 - May 2025. All three positions will henceforth be managed through the South African Polar Research Infrastructure (SAPRI) hosted within the South African Environmental Observation Network (SAEON). Deadline - 07 December 2023.

Full details and applications in the link below:

APPLICATIONS MUST BE SUBMITTED VIA SAEON (click here to redirect for details).

DEADLINE: 07 December 2023

An overview documentary of what you might expect in these positions can be viewed here and further insight about our science gained by listening to a public talk (here) or viewing our publications.

Additional information about the positions and a background to the programme can be found on our programme history, 'working with us' and FAQ pages.

If you want a good idea of what life as a sealer is all about on Marion, consider purchasing a copy of our book - 'Pain forms the Character' 

Want to help us continue this globally unique research? Support the programme.

OBITUARY: Prof Rudi van Aarde (Marion Island ‘sealer’; 1974/75/76)

A Marion Island sealer stalwart, Rudi van Aarde, sadly passed away on Friday 21 July 2023. As Sealer #5 in the MIMMP chronological hierarchy, Rudi spent 18 months on Marion Island from 1974/75 to 1975/76 (M31 & M32 teams) studying southern elephant seals (SES) together with Patrick Condy (Sealer #2) although his primary involvement was to study the population ecology of the introduced, feral domestic cat at the island.

Rudi van Aarde (bottom right) as part of the M31 overwintering team at Marion Island. Photo credit: ALSA

Rudi van Aarde (right) during the cat eradication era at Marion island

Upon completion of his MSc dissertation on the cats, he headed off to the French Kerguelen Islands for a few months in the spring/summer of 1977/78 to service a collaborative study on SES between the MRI and Terres Australes et Antarctiques Francaises (TAAF) with the endorsement of the South African Scientific Committee for Antarctic Research (SASCAR). Here he applied his Marion Island experience of SES research on the large SES population of the Courbet Peninsula, Iles Kerguelen. After he was appointed to the lecturing staff of the Department of Zoology at UP (in 1986), he furthered his involvement in SANAP as a principal investigator for studies on the SES from 1986 to 2000 with Ian Wilkinson (Sealer #27) as his PhD student. He was also involved with research on the introduced house mice population of Marion Island. Centrally involved with the planning and execution of the feral house cat extermination programme which lasted from 1977-1993, he personally supervised the release of the first control measure, the morbillivirus feline panleucopaenia, on Marion Island in March 1977 from aboard the SAS Protea.

Over thirty years of conservation ecology research (primarily ecological restoration and African elephant research) followed. Our sincere condolences go to his family and friends. May he rest in peace.

Marthán N. Bester, 26/07/2023

NEW PAPER! Killer whales at Marion Island are more social when there is more food

Since 2006, the Marion Island Marine Mammal Programme (MIMMP) has continuously monitored the killer whale population at Marion Island. Through photo analysis, we have identified 69 individuals at Marion Island, 21 of which were calves born during this period. Various aspects of killer whale ecology, diet, movement social structure and demography have been studied providing insight into how this population compares to other global populations.

A pod of killer whales patrol the Marion Island coastline in search of prey. Photo: Rowan Jordaan

In a new study led by MIMMP Research Assistant and past PhD student, Rowan Jordaan, recently published in Ecology and Evolution, nearly 90 000 photographs taken over 4 739 sightings during 12 years were analysed and used to assess whether the survival of killer whales at Subantarctic Marion Island was influenced by social structure and prey. Prey included species eaten whilst at Marion Island (i.e. Southern elephant seals, king penguins etc.) as well as prey eaten when these killer whales are not at the island (i.e. Patagonian toothfish). We also tested if these same prey species influenced killer whale social structure and reproduction (number of calves) during this same time.

A young killer whale, 4-year-old M062 plays in the swell at Watertunnel Beach. Photo: Rowan Jordaan

Results show that the more social killer whales are, the higher their chance of survival and the greater Patagonian toothfish fishing effort, the greater the survival of Marion killer whales. Furthermore, Marion Island prey was shown to influence the social structure of these killer whales as they were more social when there were more southern elephant seals present at the island. Lastly, none of the prey species included in analyses showed any relationship to the number of killer whale calves born and no environmental variables had any impact on survival or social structure.

Adult male killer whale (M001) sneaks close to a beach hoping catch an unsuspecting king penguins or elephant seal. Photo: Rowan Jordaan

These results suggest that fishery-linked resource availability may be an important influencer of Marion Island killer whale survival. Results suggest that killer whales are able to adjust their social structure in response to changing prey which leads to an increased chance of survival. Lastly, reproduction is not linked to variation in prey numbers suggesting that there are more factors at play in determining when calves are born into this population of killer whales.

The full paper can be read here: https://onlinelibrary.wiley.com/doi/10.1002/ece3.10144

New paper! Density-related reproductive costs and natal conditions predict elephant seal male life history

Adult male southern elephant seal fresh from a battle with another male at marion island. Photo: Kyle Lloyd

Being a male elephant seal is not easy. Few survive to adulthood and even fewer rise above the rest to become the alpha male of their beach. In a recent paper published in Animal Behaviour, MIMMP associate and former PhD student, Kyle Lloyd and colleagues, show that competition starts from birth when males grow and develop the traits needed in later life to establish and maintain mating rights and service groups (harems) of females. Costs of reproduction at adulthood may also be increased for alpha males that need to mate larger harems of females than alpha males of smaller female harems. Thus, decisions about allocating body resources to life history traits such as survival, breeding success and recruitment to the breeding population may differ for individuals that experience different densities of competing males and/or female group size, from birth through to adulthood.

Adult male southern elephant seal defending his small harem at a marion island beach. Photo: nico de bruyn

Using a long-term data set collected at Marion Island, we found that alpha males that dominated larger female harems experienced lower survival rates in later years, likely because there was a greater cost associated with mating more females and protecting their females from more male competitors. Interestingly, when looking back at population metric at birth, we found that males born in years with fewer pups (at the population level) had a higher breeding success and recruited at a younger age than males born in years with more pups. This suggests that males experienced competition for resources during early life and that this competition was reduced when there were fewer individuals to compete against. These findings are interesting because they show how the density of both males and females can have long-term consequences throughout a male’s life. You can read more about our study in Animal Behaviour.

In the news! New paper on the development of at-sea behaviour in male southern elephant seals at Marion Island

The at-sea behaviour of southern elephant seals is largely influenced by their ontogeny, which refers to the development of a seal from one life stage to the next. As seals age and grow, they experience changes in their morphology and physiology, which influences their diving abilities and movement patterns.

In our latest article published in the Journal of Experimental Marine Biology and Ecology, we aimed to observe the at-sea diving behaviour of male southern elephant seals from Marion Island - an aspect not previously studied.  

An adult male southern elephant seal at marion island, fitted with a satellite-linked time-depth-recording tracking device. photo: nico de bruyn

Between 2005 and 2011, satellite trackers were deployed on 23 different male southern elephant seals of various ages. Trackers recorded seals’ locations, dive durations, dive depths, surface durations and dive frequency. This allowed us to distinguish two behavioural modes; namely when seals were moving within a small area, and potentially foraging, and when seals were transiting between areas. We constructed models with this data which determined the influence of age class and behavioural mode on the diving behaviour of male southern elephant seals.

We found that juvenile seals travelled the furthest distances from Marion Island and were in transit mode for most of their dives. This behaviour was attributed to the younger seals’ less developed ability to locate food, and their smaller body size, leading to lower energy requirements. Juvenile seals also displayed shorter dives and reached shallower depths which was expected given their physiological limitations. Moreover, younger fatter seals are more buoyant and have limited oxygen reserves which limits how deep they can sink.

Fig. 1 from Lasch et al. 2022. (A) State-space modelled locations for 23 male southern elephant seals tracked from Marion Island between 2005 and 2011. (B) The average maximum distance travelled (km) by juvenile (n = 5), sub-adult (n = 8) and adult (n = 10) male elephant seals from Marion Island.

In contrast, sub-adult and adult seals stayed relatively closer to the island and spent most of their dives in searching mode. These older age classes also displayed longer and deeper dives and spent more time at the surface than younger seals. Sub-adult seals experience a secondary growth spurt, growing up to 10 times in size. This drastic growth increases their energy requirements and enhances their physiological capabilities, which enables them to exploit food patches for longer periods of time. Moreover, their longer surface durations are explained by their need to recover their oxygen supplies after long and deep dives.

Observed differences in the at-sea diving behaviour seem to reflect changing physiological abilities as seals mature. For male southern elephant seals, changes in physiological ability necessitate behavioural plasticity, which may be the key to survival and future breeding success.

To find out more, check out the full article HERE

Lasch KG, Tosh CA, Bester MN & de Bruyn PJN. 2022. The ontogeny of at-sea behaviour in male southern elephant seals (Mirounga leonina) at Marion Island. Journal of Experimental Marine Biology and Ecology (in press). https://doi.org/10.1016/j.jembe.2022.151833.

Field Assistant Vacancies for Marion Island 2023-24 - CLOSED

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2023 - May 2024. All three positions are embedded within the research programme: "Marion Island Marine Mammals in Changing Environments: Individual Heterogeneity and Population Processes", maintained through the University of Pretoria.

For instructions please read the advertisements carefully here:

Mammalogist- Seals / Killer whales

Application link  below:

APPLICATIONS MUST BE SUBMITTED VIA OUR ONLINE SYSTEM*(click on text to redirect).

DEADLINE: 7 November 2022

*Emailed submissions will not be accepted.

An overview documentary of what you might expect in these positions can be viewed here and further insight about our science gained by listening to a public talk (here) or viewing our publications.

Additional information about the positions and a background to the  programme can be found on our programme history, 'working with us' and FAQ pages.

If you want a good idea of what life as a sealer is all about on Marion, consider purchasing a copy of our book - 'Pain forms the Character' 

Want to help us continue this globally unique research? Support the programme.

News just in! An amazing geospatial database for the sub-Antarctic Prince Edward Islands is now freely available.

Figure 2 from Rudolph et al 2022: The datasets created from the (A) digital surface model (DSM), using Marion Island’s datasets as an example. (B) A slope raster and contour lines, (C) an aspect raster and (D) hydrological features such as drainage lines and lakes. The hillshade raster has (E) minor artefacts caused by interference in reflectance data by either cloud cover, scoria or snow. (F) Regions on Marion Island where artefacts in the DSM will affect the accuracy of derived geospatial data.

In exciting news, researchers working on data from sub-Antarctic Marion Island and Prince Edward Island have produced and published a detailed topographical and hydrological geospatial database – produced from a 1 m x 1 m digital surface model of the Prince Edward Islands.

The Prince Edward Islands are considered sentinels for terrestrial and marine research in the southern Indian Ocean. Their location, just north of the present-day Antarctic Polar Front, combined with the hyper-maritime climate, creates the perfect opportunity to study the ecosystem responses to climate change.

Prior to this publication fine-scale, high resolution geospatial data for both multi-and transdisciplinary research was missing. This resource will be a crucial component in allowing researchers to better analyse fine-scale biotic–abiotic interactions of the Islands’ landscape and

ecosystems especially within the context of climate change and the impacts of invasive species.

Lead author Liezel Rudolph expressed the value of such a research resource saying, “… it will facilitate collaborations between scientists in the abiotic and biotic fields, and, as it’s freely available, it invites young scientists, school teachers and the general public to use the data for their own education or interests!”

Not only will this resource benefit scientific endeavours it will additionally aid in education and conservation efforts particularly looking forward to the planned mouse eradication programme on Marion Island which will require detailed and precise geospatial data to support the planning of the world’s largest mouse eradication programme from an island (if successful).

FIGURE 4 from Rudolph et al 2022: A preview of the map indicating names and codes of beaches and zones used in marine mammal monitoring research programmes (MIMMP research) at Marion Island.

The database contains vector files, raster data sets, and maps of topographical and hydrological parameters, which are freely available to download from Figshare, which is an open access data repository. Included within this are maps indicating names and codes of beaches and zones used in the MIMMP’s mammal monitoring research programmes on Marion Island with detailed descriptions and coordinates to provide for cross-referencing with our very own database (figure above).

With such a vast data resource now freely available, the authors encourage the South African polar science community to share data on similar platforms to improve the research resources available.

The full suite of data can be downloaded HERE.

Citation

Rudolph EM, Hedding DW, De Bruyn PJN, Nel W. An open access geospatial database for the sub-Antarctic Prince Edward Islands. S AfrJ Sci. 2022;118(9/10), Art. #12302. https://doi.org/10.17159/sajs.2022/12302

Sealer Diaries: A day in the life of a Marion Sealer

Written by Mike Ross (M79)

Before I came to Marion Island, I asked several old Sealers what a typical day on Marion looked like. Most replied that there was no such thing as a “typical day” on Marion, an answer which, although undoubtedly truthful, was not especially helpful. Since I have now spent some time on Marion and have been inducted into the hallowed community of Sealers, I will do my best to provide an answer to the “typical day on Marion” question which is both truthful and informative. If nothing else, I will at least describe a single day in the life of a Sealer on Marion Island. Bear in mind that we Sealers have only just arrived on Marion (well 3 months ago, but it feels much shorter than that), and that we are yet to experience the mayhem of the breeding season, which will be quite different to a day during the quieter winter months. Having said that, this is a typical day…

First some background. Sealers on Marion work with both southern elephant seals (Mirounga leonina) and two species of fur seals, though mainly elephant seals. Our schedule is generally governed by the 10-day elephant seal census, which covers all the beaches on the eastern side of the island. Every seal born on Marion is tagged, with all individuals born in a year given the same colour tag (a different colour to those born in other years), but a unique tag number. The census typically takes five days (and a sixth if you include the walk back to base from one of the further huts), with three nights away from base at various huts scattered around the island and involves recording all the elephant seals one encounters at beaches around the island, both tagged and untagged. While simple in principle, in practice it is more challenging, as one must get close enough to read the numbers on a tag, while avoiding getting chomped by the rather large, and occasionally quite irritable seals. The remaining four days are spent tagging fur seals, recording previously tagged fur seals, processing scat, entering data or helping with killer whale observations. Back to the crux of this blog!

A young elephant seal bull and female hauled out. These seals are censused every 10 days on the eastern side of the island © Mike Ross

For some reason I woke up at 5:30 am, and given I’m a morning lark, I decided to make the most of my alertness and get stuck into this blog post. After an hour of writing, I packed the last few items into my bag. I was scheduled to finish up censusing elephant seals just north of base, but planned to return to base in the afternoon, so my bag wasn’t too full. I packed my notebook and pencil, waterproof slate (for when it invariably starts raining), binoculars, PG camera (more on this later), tags for foreign seals and tag applicators, waterproof pants and rain jacket, PLB (personal locator beacon in case of emergency), personal camera, a flask full of tea and snacks (you can never have too many, but you can certainly have too few – a most unpleasant experience). I quickly ate breakfast, signed out on the register (so people could locate me if I didn’t come back) and left just before 8 am.

I decided to walk to the furthest point and census the beaches on the way back. The weather teased me – it was sunny over the interior, but I was walking in a soft drizzle, a classic Marion soft, subtle soaker. Nevertheless I enjoyed the 1h30 hour walk to Blue Petrel Bay to the north of base, and marveled at the growing Wandering Albatross chicks and Giant Petrels I spotted along the way. Sometimes I take these sights for granted, but am quickly reminded of how lucky I am when I take a moment to reflect that “I’M ON MARION FREAKING ISLAND” (a direct quotation I discovered on the inside of one of the hut doors which seems particularly apt). At Blue Petrel Bay my work for the day began in earnest.

The beaches are relatively quiet at the moment, with most of the seals fattening themselves up in the ocean before the breeding season. As a result, census went quickly. I came across many tagged seals and recorded their tag colour and number. The highlight was seeing my first Red White (Red White 029), an eight year old male who was tagged in 2014. So far we haven’t seen many fully grown adults, but they are sure to be on their way as breeding season approaches. I proceeded to PG the Red White. Essentially you take multiple photographs of the animal from different angles and combine all these images to produce a 3D depiction of the animal, which can then be used to estimate the animal’s weight. Effectively you can weigh a multiple ton elephant seal with one finger. There are nine beaches between Blue Petrel Bay and base, some with multiple divisions, and I checked them all, encountering 84 seals. Unfortunately I didn’t see any killer whales during my census, but I did briefly stop to admire the view from the top of one of the beaches called Ship’s Cove. Just before I reached base, I stopped to check in with Monica (M79 sealer focused on killer whales), who was at Kill Point, on the lookout for killer whales. By 2:30pm I was back at base.

“I’M ON MARION FREAKING ISLAND” moments as you look down on Ship’s Cove ©Mike Ross.

The day wasn’t done yet. After a quick lunch, M79 sealer Banele and I headed out in an attempt to catch a fur seal mom and her pup. We were hoping to deploy a GLS device (a archival tracking device) on the mom and tag her pup. Alas, the pair conspired against us, and the pup went swimming with his friends, leaving us unable to identify him. Banele and I sat behind a rock for 20 minutes hoping the situation would change, but it appeared to be in vain. I checked in with Monica again (she was at Kill Point for 8 hours, so there was plenty of time for that) and then headed back to base. Once at base, I spent the next hour inputting the data I had collected from my day in the field and clearing the slight data backlog. The work day was now officially over. I’d walked 15.6 km outside (though walking on Marion is much harder than the distances alone suggest) and would go on to do over 28000 steps for the day.

Still, the day wasn’t done yet. On Marion we seem to have never-ending skivvy (cleaning) duties, including the base skivvy, the science corridor skivvy, our accommodation skivvy, kitchen skivvy and braai skivvy, which we do on a rotational basis. Today, being a Monday, was base skivvy, so I spent 30 minutes cleaning various sets of staircases, my job for the day. The last thing I desperately needed was a shower. By the end of the day, one exudes this awful stench of seal and penguin excrement, which as a sealer you become somewhat accustomed to, but the rest of the base personnel do not. Having a shower therefore constitutes an essential part of maintaining relationships with everyone else on the island and avoiding being kicked out of base.

By 7 pm, I had finished everything, just in time for dinner, which after a long day out, is always a highlight. After dinner I organised what I would need for the following day and then caught up on messages and emails. The day ended with some quiet time reading, and then I was off to bed, ready to do it all again tomorrow.

My first Red White tag for the season, an 8 year old bull ©Mike Ross.

Census repeats itself at least every 10 days throughout the year, and while every day is different, I hope you have some idea of what a typical day looks like at this time of year, and if nothing else, at least what happened on this particular day. Marion is the most incredible place, and I feel so lucky to be here. While this post dives into what exactly a Sealer gets up to on Marion, upcoming posts will help explain why the island is so special, and why our work here is so important, so stay tuned! 

Two-year funded Postdoc Position: Space weather influences on marine mammal movement

We are seeking a postdoctoral candidate to investigate whether space weather influences marine mammal movements at sea. Specifically, this study will aim to collate telemetry data from a range of Southern Ocean marine mammal species and use these to investigate correlation between the recorded movement patterns with space weather events such as, for example, sun cycles and geomagnetic storms. Species or taxon specific differences will be assessed, and mechanisms through which space weather could influence the movement of marine mammals will be explored.

The position is funded for 24 months through a NRF South African National Antarctic Program Postdoctoral Grant at the University of Pretoria (Pretoria, South Africa) and will work closely with the South African National Space Agency (Hermanus, South Africa). Project start date is negotiable, but aiming to start as soon as possible.

We are looking for a self-starting, independent and highly motivated colleague who is interested in marine mammal movement ecology, space weather, habitat modelling and science communication. PhD required, with background in either ecology/zoology/physics. Skills in statistics, and GIS; competency with GIS and R/Python/Matlab is essential; strong writing skills, ability to adapt/learn quickly are a major plus. Ability to work in Hermanus for at least part of the project is a plus as well.

If you have questions or are interested in the position, please email Dr Mia Wege at mwege@zoology.up.ac.za and attach your CV.

Position will be open until filled.

The project involves collaboration between the Mammal Research Institute (MRI) at the University of Pretoria and the South African National Space Agency (SANSA). The project will be led by Dr Mia Wege, working closely with a team of experts in their respective fields (Dr Els Vermeulen (MRI), Dr Pierre Cilliers (SANSA), Dr Stefan Lotz (SANSA), and Prof Nico de Bruyn (MIMMP - MRI)).

A new field year, a new team.

In April three new team members set sail for the sub-Antarctic where, for the next 14 months, Marion Island will be their home.

New sealers Michael Ross (second from left), Banele Dosi (center) and killer whaler Monica Leitner (third from right) head out on their first walk on the island accompanied by the previous year’s team © Rowan Jordaan.

This rugged island, only 25 km long and 17 km wide (290 km2 in area), is accessible only to researchers, who visit the island for 14-month stints to study the fauna and flora that call the island home. Many of the marine mammal and bird species spend most of their lives at sea foraging in the Southern Ocean, coming to the island only to breed and moult.

After arriving late in the month, the two new sealers, Banele Dosi and Michael Ross, and Killer whaler, Monica Leitner had to wait patiently for the weather to clear enough to allow the helicopters to fly off the S.A. Agulhas II before their adventures could begin on the island. Located in the infamous “roaring forties”, the island weather can shift suddenly from sunshine, to ice pellets, to rain and snow, all accompanied by predominating gale force winds. It is a harsh but magnificent landscape.

The sealers exercise their Marion knees as they head up from the beach at Macci bay © Yinhla Shihlomule.

After several days the team was flown onto the island, where for the next month they would be taught what their positions entail and learn the tricks of the trade from the previous team members during take-over. After this period the old team would head back to the South African mainland leaving the three new members, along with the rest of the M79 team, on the island until next year April.

During their time on the island the team will be responsible for collecting long-term monitoring data from the region’s top predators; southern elephant seals, sub-Antarctic fur seals, Antarctic fur seals and killer whales. This crucial data allows researchers to study the response of these animals to environmental change in the region.

Caitlin van der Merwe’s excitement is palpable as she finally explores her study site © Yinhla Shihlomule.

Joining the team for only the take-over period, MIMMP MSc student, Caitlin van der Merwe, also has the opportunity to familiarize herself with her study species. Caitlin is currently working with elephant seal tracking data to look at the at-sea behaviour of intermittent versus continuously breeding female southern elephant seals and the environmental conditions that impact this. With this project building on her previous desktop-based Honours work on the same species it is especially exciting for Caitlin to finally see her study site!

Field Assistant Vacancies for Marion Island 2022-23 - CLOSED

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2022 - May 2023. All three positions are embedded within the research programme: "Marion Island Marine Mammals in Changing Environments: Individual Heterogeneity and Population Processes", maintained through the University of Pretoria.

For instructions please read the advertisements carefully here:

Mammalogist- Seals / Killer whales

Application link  below:

APPLICATIONS MUST BE SUBMITTED VIA OUR ONLINE SYSTEM*(click on text to redirect).

DEADLINE: 15 October 2021

*Emailed submissions will not be accepted.

An overview documentary of what you might expect in these positions can be viewed here and further insight about our science gained by listening to a public talk (here) or viewing our publications.

Additional information about the positions and a background to the  programme can be found on our programme history, 'working with us' and FAQ pages.

If you want a good idea of what life as a sealer is all about on Marion, consider purchasing a copy of our book - 'Pain forms the Character' 

Want to help us continue this globally unique research? Support the programme.

Congratulations Prof. Marthan Bester! MIMMP founder is awarded for Excellence in Wildlife Research and Management

Prof. Marthan Bester receiving his SAWMA lifetime achievement award.

The Southern African Wildlife Management Association awarded MIMMP’s Prof. Marthán Bester with the Excellence in Wildlife Research and Management Award at their 50th-anniversary conference last week!

Marthán’s lifelong dedication to marine mammal conservation, management and research in the Southern Ocean and Antarctica has inspired not only his fellow academics and policy makers, but also thousands of undergraduates, schoolchildren and members of the public through his publications, lectures and radio/television appearances. 

Prof. Bester completed his PhD on Subantarctic fur seals at the University of Pretoria (UP) in 1978, and since then has frequently undertaken research expeditions to various Southern Ocean islands and Antarctica. Marthán served as an Antarctic Research Officer (Mammals) to the Department of Environmental Affairs between 1982-1996, after which he became a lecturer at the University of Pretoria. In 2002 he was promoted to Full Professor. Marthán retired in 2014, but remains affiliated to the University of Pretoria as Emeritus Professor and as Senior Research Fellow with the Mammal Research Institute.  

Marthán has an extraordinary legacy on Marion Island, where he conceived, initiated, maintained, and managed (uninterrupted since 1983) until his retirement the intensive Marion Island southern elephant seal mark-recapture research endeavour that the MIMMP is famous for today. This programme stands as one of the longest running and most important large mammal datasets in existence globally and is the foremost of its kind for the species. Marthán also played a crucial role in coordinating the almost 20-year long (1972-1991) successful eradication of invasive cats from Marion Island.

To this day, Professor Bester remains a tremendously productive and influential international scientist. Perhaps his greatest legacy, however, lies in the multitude of students guided, collaborations built with local and international scientists and multiple training and networking opportunities forged for the next generations of scientists and environmental managers in South Africa. Because of their expedition research and experience gained, most of the Marion Island “Sealers” and “Cat hunters” have completed postgraduate degrees and many have gone on to hold influential positions in research and conservation both nationally and internationally.

Marthán’s achievements are not only a result of his tremendous foresight and passion for the Southern Ocean, but also of dedication and a remarkable capacity for hard work while maintaining a friendly and welcoming demeanour to all.  

Sincere congratulations on winning this prestigious award Marthán!! The MIMMP is exceptionally proud to be following in your footsteps and continuing the work of such an excellent ambassador for Antarctic research, influential marine mammal scientist and role model.

Can we use molted hair stable isotope and amino acid δ15N values to assess foraging specialization?

Naturally shed tissues, such as hair or feathers, can be sampled using minimally invasive approaches and are increasingly used for stable isotope-based dietary studies. Between November and February each year, southern elephant seals (SES) haul out ashore to undergo a ‘catastrophic’ moult. Their hair and layers of skin are shed while fasting and are replaced by a new pelage before returning to sea. In this latest MIMMP paper led by Dr. Nico Lübcker and colleagues, bulk tissue and amino acid carbon (δ13C) and nitrogen (δ15N) stable isotope values of hair, epidermis, and whiskers of SES were used to evaluate if hair and epidermal isotope values provide dietary information that is ecologically meaningful. Because the shed hair is potentially synthesized while these animals are fasting, it is possible that the stable isotope values measured in the hair do not provide an accurate reflection of the isotope values of their prey.

In the paper “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” published in Marine Ecology Progress Series, it is demonstrated that the new SES hair is rapidly synthesized from recycled endogenous sources while fasting. Both the bulk tissue and amino acid δ15N values are adversely influenced by the physiological changes associated with fasting. This was similarly observed in the portion of their whiskers synthesized while on land which has been previously published (Lübcker et al. 2020; https://doi.org/10.1007/s00442-020-04645-5).

This study is the first to combine bulk tissue and amino acid isotope values to describe how naturally shed tissues that are synthesized while animals are fasting, and affected by physiological factors. Such physiological method validations are required to understand the limitations of these sampling approaches, and emphasizes the need to differentiate between ecological and physiological factors that influence tissue isotope values before drawing inferences about their foraging and movement ecology. 

Figure from Lubcker et al. 2021. Nitrogen (δ15N) isotope values measured in temporally overlapping, paired hair (circles) and chronologically sub-sampled whiskers (lines) of young-of-the-year (YoY; n = 16 individuals) and adult female (AF; n = 4) southern elephant seals. The mean (±SD) epidermis δ15N values of n = 5 different adult females are also shown for comparison. Solid lines: fitted Loess smoothers with associated standard error (gray shading); vertical gray rectangle: portion of the whisker grown concurrently with hair synthesis during the molt fast; purple dashed lines: position along the whiskers that reflects at sea foraging with the plot position (x-axis) set to zero, signifying the end of the molt fast (Lübcker et al. 2020a). The hair and epidermis bulk tissue isotope values were overlaid with the whisker δ15N values to illustrate the position along the length of the whiskers where the δ15N values were most comparable. The hair and epidermis δ15N values resembled the whisker δ15N values during a known catabolic state.

This finding is topical and challenges the notion that naturally shed hair and epidermal isotope values are useful for dietary reconstructions. Molt in SES is energetically demanding. Stored proteins are catabolized for hair synthesis, leading to additional enrichment of the δ15N values incorporated into the newly synthesized hair. Although naturally shed tissues are easy to collect, the timing of tissue synthesis relative to the life history of the organism should be considered when interpreting stable isotope data. Despite these limitations, molted hair can be used to detect extreme foraging events, 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.

Read the full article HERE

Prof. Nico de Bruyn contributing expert reviewer for “What Works in Conservation”

“What Works in Conservation” is a free online practical guide to ecological decision making. An initiative by the ‘Conservation Evidence’ project of the University of Cambridge (UK), this free online book draws upon an opensource database of over 7800 scientific articles, reports and reviews focused on the outcomes of various conservation decisions and the lessons learnt therefrom.

Aimed at everyone from farmers to policy makers, “What Works in Conservation” provides an evidence-based summary of various conservation interventions and whether such interventions have been successful or efficient in achieving the desired outcomes from multiple case studies around the world.

Despite taking a very comprehensive approach, this book provides a rapid overview and key messages to consider for particular interventions, making the most important information digestible and accessible to any conservation decision maker.

The MIMMP is proud to be represented in this initiative with Prof. Nico de Bruyn being part of a panel of expert reviewers to assess the efficacy of various interventions to “Marine and Freshwater Mammal Conservation” (Chapter 14).

CLICK HERE to download your copy of “What Works in Conservation” and read more about this wonderful opensource initiative making reliable and up-to-date conservation information accessible to everyone.

NEW PAPER: Moult as related to age and breeding state of female southern elephant seals

Southern elephant seal on marion Island starting to moult around its face. Photo credit: Leandri de Kock

Between November and February each year, southern elephant seals haul out ashore to undergo a ‘catastrophic’ moult whereby they shed hair and layers of skin while fasting.

In the latest MIMMP paper by Leandri de Kock and colleagues, moult scores from 4612 female southern elephant seals (over 32 years) were used to quantify moult timing (phenology) and haulout duration (the time from arrival ashore to departure) at Marion Island. This is the most comprehensive study of female southern elephant seal moult haulout to date, both in the number of animals investigated and the time-frame of data collection.

In the article published recently in Scientific Reports, no clear phenological shifts were observed in either moult timing or haulout duration over the 32-year study period. Moult timing was strongly influenced by age, with juveniles initiating moult progressively later in the season as they aged until reaching adulthood (4 years and older) when annual start dates become fairly consistent over time. In contrast, moult haulout duration was not constant among adults and instead showed a decreasing trend with age. On average, the study found that female elephant seals hauled out to moult for 31,25 days each year.

Figure from de Kock et al. 2021. A) Mean moult haulout duration (with 95% confidence intervals) of female southern elephant seals at Marion Island according to age and breeding state. B) Observed mean (black circles) and predicted change (linear regression) in moult haulout duration of female elephant seals with variation in sea surface temperature (SST) and a linear regression (with 95% confidence intervals). Individual data points are plotted on both figures (pink – juveniles, green – non-breeding adults and blue – breeding adults).

Interestingly, moult haulout duration and timing were largely unaffected by climatic and oceanographic metrics of the Southern Ocean surrounding Marion Island.

Moult in elephant seals is energetically demanding and differences in moult haulout duration for females of different ages could be explained by individual variations in body mass, although other drivers such as hormones cannot be discounted. Given the ease of monitoring annual changes in moult haulout duration compared to changes in body mass, future studies are encouraged to investigate whether moult haulout duration can act as a proxy of body mass (condition) for female elephant seals.

Such long-term individual-based studies enjoy clear advantages over population-level data, by being able to account for age and linkages between life-history stages. Such information for moult timing and haulout duration is likely to be useful as auxiliary data in life-history theory models.

Well done to Leandri and colleagues for this exciting work!

Read the full article HERE

OBITUARY: Prof Gideon Rossouw (Gough Island 'sealer' 1975/76)

Gideon Rossouw, 2020. Photo: MN Bester

We regret to inform that, sadly, another stalwart ‘sealer’ has recently passed away. Gideon Rossouw (Gough 21; 1975/76), together with Marthán Bester, investigated the population ecology of the large Subantarctic fur seal population at Gough Island, as well as the resident small breeding colony of southern elephant seals. While training as a zoologist at the University of Stellenbosch, he was recruited to spend the summer at Gough Island as one of two seal researchers. He later went on to research elasmobranch fishes at the then University of Port Elizabeth (Nelson Mandela University), also making a name for himself as a very accomplished palaeontologist, especially on Karoo vertebrates (such as mammal-like reptiles). He lectured widely on this topic and the comparative anatomy of vertebrates. He often toured fossil sites and established fossil collections, together with his students, all over the Karoo. In 1980, he briefly returned to Gough Island for the takeover to augment the seal research of 1975/76. Gideon retired from NMU as Head: Department of Zoology in 2015, eventually moving to Dana Bay, where he passed away on 4 June 2021 at the age of 70. Preceded in death by his wife Engela, he is survived by his son, Jan-Hendrik, daughter-in-law and two grandchildren.

Gideon (left) and Marthán on Gough Island during 1975/76

Marthán N. Bester, 24/05/2021

NEW PAPER: Marion Island killer whales are more social when there's more food

The Marion Island Marine Mammal Programme (MIMMP) continuously monitors the killer whale population at Marion Island, and since 2006 (when the current photoidentification catalogue was started) 69 individuals have been observed, of which 21 are calves born during this period.

An adult female (M002) spy-hops after a successful king penguin hunt at Ship’s Cove. PHOTO CREDIT: Rowan JordaaN

A new study led by MIMMP PhD student, Rowan Jordaan, made use of this long-term data in a recently published article in Animal Behaviour. They used nearly 90 000 photographs (from 4739 sightings over 12 years) to assess the social structure of killer whales at sub-Antarctic Marion Island across different periods of the year corresponding to fluctuations in prey availability: southern elephant seals, sub-Antarctic fur seals, king and macaroni penguins are most abundant between September to December (“peak”) and least abundant between January to August (“off-peak”). Analyses showed significant differences between various measures of social structure between these peak and off-peak periods.

Killer whales were more social during the peak period when there was more prey available, by exhibiting higher probabilities of socialising with other individuals, forming stronger associations, showing less division in the population and social groups consisting of more individuals. As a whole, the social network during the peak period was compact with very short distances between all individuals. In contrast, killer whales were less sociable during the off-peak periods as individuals formed smaller groups that were less likely to socialise with others.

FIGURE FROM JORDAAN ET AL. 2021. Network plots for Marion Island killer whales over (a) all peak periods (September - December) and (b) all off-peak periods (January - August) during 2006- 2018. Each node (coloured circle) represents an individual killer whale and each vertex/edge (line between two nodes) represents the association between two killer whales. Numbers in nodes indicate the unique ID code for each individual. Size of nodes and thickness of edges are a direct representation of how social individuals are.Individuals were grouped into social units, represented by different colours

These results are typical of a process called fission-fusion, which occurs in a population when individuals leave social groups to form smaller groups (fission) or come together to form larger groups (fusion). For killer whales at Marion Island, this balance appears to shift during the year in relation to the amount of prey available in an effort to reduce competition and to maximise the net energy intake per individual, ultimately benefitting the population as a whole. Similar responses to changes in prey availability have been observed in various animal societies such as wolves, whales, lions, wild dogs and spotted hyenas.

Well done to Rowan and colleagues on this publication, which provides further support to the idea that prey availability is an important determinant of social structure in social predators.

Read the full article HERE.

SHIP IN THE BAY - the M78 team arrives on Marion Island!

The SA Agulhas II arrives at Marion Island for the 2021 relief voyage. PHOTO CREDIT: Nico de Bruyn

The new overwintering team M78 has arrived on Marion Island!

For these team members, like our killer whale researcher Danielle Conry, this moment has not only been a life-long dream but also one that has been filled with uncertainty over the last year due to the restrictions (and almost entire halting of the 2020/2021 scientific programme on Marion Island) caused by the COVID-19 pandemic.

After two weeks in quarantine in Cape Town and a few negative COVID tests later, Danielle and her team mates now finally get to enjoy the freedoms and adventures of Marion Island. Danielle joins up with her experienced sealer team mates Yinhla Shihlomule and Frikkie van der Vyver (who were part of the greatly reduced scientific voyage in September 2020) and they will now show her the ropes (and hopefully some mires) associated with the MIMMP field work.

A big welcome to our MIMMP team for the 2021/2022 overwintering period!

MIMMP’s killer whale researcher, Danielle Conry (middle), joins her fellow team mates Yinhla Shihlomule (left) and Frikkie van der Vyver (right) on Marion Island. PHOTO CREDIT: Nico de Bruyn

NEW ECOLOGY PAPER : Female seals that breed young have a slower rate of ageing

At Marion Island, some elephant seal pups have a ‘golden spoon’ start to life. We measure this through their weaning mass, with the ‘golden spoon’ pups being the heavier ones.

‘Golden spoon’ females tend to reproduce at a younger age than those that were relatively small at weaning. In a new paper published in Ecology, Chris Oosthuizen and colleagues show that an early age of first reproduction also correlates with a slower rate of ageing, and a higher expected fitness. 

A 17-year old southern elephant seal mother with her 10-day old pup at Ship’s Cove, Marion Island. Female seals that breed young, also enjoy a slower rate of ageing and produce more offspring in their lifetime than those that delay breeding. Photo credit: Chris Oosthuizen

How animals age in the wild is central to understanding their life-history evolution. Senescence (age-related declines in fitness components) stems from a weakening in the strength of natural selection with age. Rapid development may accelerate the onset of senescence (the “developmental theory of aging”) or allocation to early life performance may come at a cost to late-life performance (the “disposable soma theory”).

This study used capture-recapture data of over 7000 female southern elephant seals collected over almost 40 years at Marion Island to test for negative or positive correlations between early-life and late-life traits. It specifically tested whether the onset and rate of actuarial senescence (the increase in mortality hazards with age) correlated with the age of first reproduction.

Because marine mammals spend most of their lives at sea, the analysis was specifically designed to study early-late life-history correlations in wild animal populations where some breeding attempts and all deaths go undetected.

Fig. 1 (a) Survival trajectory of female elephant seals breeding for the first time at age 3. (b) Survival trajectory of females breeding for the first time at ages 4 or later. Solid circles correspond to the annual survival probability of experienced breeders. The regression line indicates the logit-linear relationship between age and survival of experienced breeders. Early breeders had a lower senescence rate than delayed breeders. The age at the onset of senescence (where survival probability starts to decline at old age) is indicated with a dotted line. (Oosthuizen et al. 2021)

Females with an early age of first reproduction survived better than those with delayed reproduction in both the short- and the long-term. Females breeding at a young age had lower rates of senescence when they were old (above 17 years of age), and produced more offspring during their lives than those that delayed breeding.

Congratulations to Chris and colleagues for this excellent publication and for translating the almost 40 years of MIMMP field research into scientific outputs which further our understanding of marine mammals!

Read more and access the paper HERE