Kerguelen saga: part deux — Trekking, fieldwork and cave abodes (episode 4)

Since 2016, the Ocean Tracking Network and the Institut National de la Recherche Agronomique (INRA) have been collaborating on a study to understand of the successful colonization of brown trout introduced to the Kerguelen Islands (southern Indian Ocean) in the 1960s. The project presents a unique opportunity to study large-scale colonization by a non-native species in the context of climate change and glacial retreat. The first OTN-supported Kerguelen trip in 2016 sent former OTN masters student, Colin Buhariwalla, to the remote Kerguelen Islands to conduct preliminary tests and establish tracking arrays. Over the next three months, OTN PhD student, Xavier Bordeleau, will be conducting brown trout tracking studies in partnership with the French Polar Institute (IPEV), and the Norwegian University of Science and Technology (NTNU). He documents his research and the rhythm of life on the remote Kerguelen Islands through photographs and journal updates.


Bonjour à tous,

The past month in Kerguelen has been quite busy and I am now catching up before going to the northern part of the island for three weeks of receiver deployments and tagging in the field – the primary reason I came all the way out here. After many years of discussions and planning, we are finally a day away from beginning this incredibly exciting research project!

La Curieuse (Photo: Clément Rio)

We are set to embark on La Curieuse, a small, 25 metre trawler, tomorrow, January 23, for a week-long trip along the northern coast of Kerguelen. We plan to deploy 53 acoustic receivers at sea, in estuaries, and in rivers and build an acoustic array to cover the entrance of other suitable freshwater systems ~25 kilometres east and west of the colonization front, with the aim of characterizing the exploration behaviour of pre-spawning adult brown trout, such as distance travelled at sea, frequency and duration of freshwater visits, and potential phenotypic differences between homing and exploring individuals. Then, we will be dropped off on the southern shore of Baie Irlandaise, where we will stay for about 10-12 days to tag 50 anadromous brown trout with conductivity/temperature acoustic transmitters in the estuary of Lac Bontemps outlet – the current colonization front of the brown trout invasion.

As we learned last year, in a place like this, everything can change in the blink of an eye. But spirits are high and the factors in our control have been well planned out – even our fishing game is on point!  

Xavier Bordeleau

Over the past month, our time was divided between all the preparation needed for this project, like programming receivers and revising deployment sites.

preparing moorings and planning the detailed logistics of the project (Photo: Xavier Bordeleau)

We also embarked on field trips to collect data on other components of the broader SALMEVOL (Salmonid Introductions to the Kerguelen Archipelago) research program conducted by the ECOBIOP research unit at the French National Institute of Agricultural Research.

This year, in addition to the telemetry project, we’ll collect data on the progression of the brown trout colonization, carbohydrate digestion mechanisms in Kerguelen brown trout, as well as aspects of gene translocation and adaptation, and brook trout and brown trout inter-specific competition.

While we’re here for the science, it’s impossible not to be consumed by the landscape and experiencing life in this remote place, along with the memorable moments it brings.  

The team carrying their equipment across rugged terrain (Photo: Xavier Bordeleau)

Some of my most memorable moments include being dropped off by the La Curieuse with my colleagues at 3:30 am, after a very rough night at sea, on a beach in the middle of nowhere, with ~90 kilograms of equipment to carry three kilometres to a cave where we were set to spend four days. Of course, with no electricity, no heat, water dripping inside, wind coming in, and dead rabbits surrounding us.

The team uses a cave as their temporary basecamp (Photo: Clément Rio)

I thought to myself “a fire would be nice,” before having the realization that there was not a single tree on the island! Quite an adventure in the magnificent Vallée de la Clarée. Celebrating New Year in a cave on the Desolation Island is quite atypical and one to remember.


After the first couple windy and rainy days, the weather turned and the sun came out and greeted us with its warmth. We welcomed it with gratitude.

(Photo: Clément Rio)

After ringing in the new year, we spent an extra two days travelling on La Curieuse to do electrofishing surveys to control the presence of brown trout in previously fish-less rivers at the south-west end of the colonization front. Being dropped off at the periphery of Plaine de Dante king penguin colony, we hiked along the crowded river to fish in the vicinity of a magnificent waterfall.

(Photo: Xavier Bordeleau)

Moments like this are the essence of why I have always wanted to become a wildlife/fish biologist.

To me, these experiences are the perfect mix of intellectual challenges, adventures in fieldwork and combining state of the art technology with local knowledge to meet our research objectives.

Ultimately, it’s about working towards protecting the natural world and making discoveries. As for the salmonids, we did confirm the presence of both juvenile and adult brown trout in other freshwater systems, so colonization is still ongoing.

King penguin colony (Photo: Xavier Bordeleau)

In early January, we hiked to Val Studer to complete electrofishing surveys and sampling of brown trout and brook trout. One thing I have confirmed here is that we, (commonly known as fish people), always have so much gear to carry – even outside the field of telemetry!

Electrofishing motor and cables, nitrogen dewar, dip nets, keep nets, surgery tools, buckets, waders and boots and more. Add personal gear like sleeping bags, clothing and food, and items begin to add up very quickly. Over the two days, each of us had ~20 kilogram back packs to carry over 40 kilometres through rivers, rocky terrain, wetlands and bogs. What is very difficult here is finding the proper footwear. Waders, rubber boots, hiking boots with gators? To most people, none of these can provide both comfort and dry feet. Not for long distances, highly variable terrain and with heavy loads to carry, anyway. Trial and error is necessary in discovering what the most tolerable solution for each person embarking on the trek is. And after a long and sweaty day marinating in waders, nothing feels better than a dip in a 4-degree lake – at least for me!

On a different note, our temporary abode, Studer cabin is very charismatic. Comprised of an assemblage of metal, container-like rooms forming a tiny village, certain moments of being there evoke feelings of being on a polar expedition. But while such cabins are adapted for cold and dry environments, it is less so for humid climates. Condensation forms on the walls and roof, which then drips inside. On the positive side, it’s still far more comfortable than a cave!

Studer cabin (Photo: Xavier Bordeleau)

Knowing that between research projects and the journey back to Reunion, we will be spending 19 nights on La Curieuse, it becomes difficult not to feel apprehensive about the travel. However, I’ve only been sea sick once, so I should make it out okay after all. I guess that’s the price of admission for having the chance to see this remote part of the world! Unlike the comfortable Marion Dufresne, La Curieuse is a small fishing trawler that has quite a reputation here with most people getting sea sick due to rough seas and the intense rolling motion of the ship. Despite its reputation, La Curieuse is a charming vessel, offering the true experience of life at sea.

(Photo: Xavier Bordeleau)

As I’ve written this, we’ve now transferred our ~3,000 kilograms of equipment on La Curieuse and we are finally ready to set sail. Nothing can be taken for granted here so every step forward feels like a small victory.

The first receiver deployments are set for January 24th. As Philippe would say: “Fingers crossed, but not arms!” Time to get to work!

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