Sea lion research on Enderby Island

Department of Conservation —  31/05/2018

by Dr Aditi Sriram, Researcher

After months of preparation we finally find ourselves in port Bluff, Invercargill. It’s an early morning in December as we step on board Evohe to set sail to Enderby Island. We sail through Foveaux straight and past Stewart Island, when it really starts to sink in that we are making our way over 500 kilometres south to spend three months on a remote island. We are sailing to Enderby Island, part of the Auckland Islands group and one of a few strongholds for the New Zealand sea lion/rapoka. Once found throughout New Zealand, these sea lions are now restricted primarily to the Auckland Islands, which is home to approximately 70% of the entire population.

Welcome to Enderby Island, part of the Auckland Islands .

Welcome to Enderby Island, part of the Auckland Islands

Over the next three months I would make up part of a four-person New Zealand sea lion disease research team, led by Sarah Michael, stationed on Enderby to investigate disease and mortality in New Zealand sea lions. This year was the second field season for this research project, funded by the Department of Conservation, through the New Zealand Sea Lion Threat Management Plan. Infectious disease is recognised as a major threat to New Zealand sea lion populations and continued and targeted research is a means to contribute towards the conservation of this species.

New Zealand sea lions.

New Zealand sea lions

After 30 hours of what was considered ‘smooth sailing’, we arrived at Sandy bay, Enderby. On arrival we had a few hours of light left in the day and a mountain of gear to unload on to the island. Being remote has its perks, but it also meant there was unloading at least 3 months’ worth of supplies, including food, research gear and personal gear. In packing for the trip, I made sure to remind myself, “minimalism is the key!”. The food order was less minimalist. Being on an island with no down-the-road supermarket meant we had to be prepared for all manner of cravings. What’s more, with no refrigerator on the island, food lists had to be well planned to ensure we had enough food and also that it would last for the time required.

It didn’t take us long to adjust to life on Enderby. There is a small research station on the island and every summer the island hosts various research teams making use of these facilities. But none would stay as long as we would so it’s fair to say we made the place feel like home. There were two bunk rooms to house us, an undercover area for food storage, and a separate hut with a kitchen, shower and office room. Just a short walk from the office was a long-drop with a magnificent view of the rata forest. Water on the island was supplied by a few large rainwater tanks. Being dependent on rain, we had to be mindful of water usage. As such we only showered once every three days, so you can imagine how we relished ‘shower days’. Although short, the hot showers were glorious and I have a new appreciation for the rejuvenating capability of a good hot shower.

Research Station.

Research station on Enderby Island

Early in the season, daylight hours were long. We started our days by monitoring the colony and recording new births. Over the first few weeks, the colony grew and spread, starting with a few harems and expanding to occupy almost the entire beach. For the research, it was important to identify when particular females gave birth, so we could age the pups. We typically watched the colony all day, using our binoculars and cameras to record unique letter and number IDs on the mothers’ flipper tags. Watching the colony was fascinating. There was always so much happening! It was a flurry of activity, with dominant males defending their territories and guarding their borders, females giving birth and, amidst all the drama, skuas loitering close by ready to scavenge on anything and everything they could get.

Sea lion colony.

New Zealand sea lion colony

For the first few days after birth, the female sea lions would stay close beside their pups. It was only after about a week that they would head back to sea to feed again. From that point onwards mothers would intermittently forage for food out at sea, while leaving their pups on the beach. It was at this time we were able to sample the pups. Navigating the chaos of the colony, we captured pups to tag, measure their body condition, and collect samples needed for disease research. As the season progressed, the colony slowly dispersed from the beach on to sward and deeper into the island, as the pups became more inquisitive about their surroundings. Witnessing the first months in the life of these pups was enlightening; progressing from what were first helpless newborn pups on the beach to becoming cheeky characters swimming in the island’s small lakes, chasing and play-fighting with each other, and finally taking the big step and heading out to sea.

New Zealand sea lion pups.

New Zealand sea lion pups

We continued to sample pups throughout the season as they spread deeper into the island. Although the days became shorter over the season, our working days became longer as the pups got harder to find. In between sampling, one of our tasks also involved performing post-mortems on pups to identify the cause of death. Pup mortality due to diseases is a major threat to the New Zealand sea lion population, identified on the Risk Assessment that preceded the New Zealand Sea Lion Threat Management Plan. We collected multiple samples during the post-mortems to investigate the role of infectious disease as a cause of mortality in the pups.

At the end of each day, we always had a hearty meal, good stories and a warm kitchen to look forward to. Dinner prep was taken in turns and never failed to deliver creative and delicious meals. Post-dinner we wound down with a game of cards before catching some very welcome sleep in preparation for the next day. We were usually woken in the mornings by the resident pair of yellow-eyed penguins, which had chosen their nesting site adjacent to the hut. Usually setting off around 6 am, they made for an early but reliable alarm clock. After breakfast, a hot coffee and the daily general knowledge quiz, we would set out again for another day outdoors.

Christmas lunch.

Christmas lunch

During our stay, we had many opportunities to explore the island and its wildlife. On a few occasions, we tramped around the island, hugging the coast. The 4-5 hour walk took us past stunning landscapes, with some incredible wildlife encounters along the way – Auckland Island snipe, giant petrels, visiting elephant seals and sooty and royal albatross to name a few. Settling into ‘island life’ was a surprisingly smooth and natural transition; working outdoors every day on the island never ceased to amaze. But our time to say goodbye came sooner than anyone expected. Needless to say, leaving the island was bitter sweet; while we looked forward to heading back to family and friends, it was hard to imagine returning to routine life after such an incredible experience. Our season on Enderby was a truly exceptional experience and a once-in-a-lifetime opportunity. It was a privilege to work in such a wild place and with such a charismatic species. I can only hope to have the chance to do it again someday!

The research team.

The research team

4 responses to Sea lion research on Enderby Island

  1. 

    Well done team and Dee. Didnt realise till now what goes on behind the scenes to save these cute little munchkins and keep them growing.

  2. 
    Susie Brown 01/06/2018 at 1:36 pm

    Thanks for the important work you have been doing, and for the well-written account of it. Congratulations!

  3. 
    Patricia Lemberg 9 31/05/2018 at 10:14 am

    congratulations to the Team and their very interesting comments about our Sea Lion population and their lives on Enderby Island – now I must research my atlas to relate to their part of our country!

  4. 

    Sounds like a pretty amazing way to spend three months. We’ve watched sea lions often at Surat Bay. They’re truly awesome, and very entertaining. You wouldn’t want to try and break up a fight between the big boys!