The Pitcairn archipelago is a group of small, isolated islands in the southern Pacific Ocean. The four islands – Pitcairn, Henderson, Ducie and Oeno – are the only Pacific Ocean British Overseas Territory and have a combined land area of approximately 47 km2.

Pitcairn Island, the only inhabited island of the four, has the smallest population of any national jurisdiction in the world. As of 2020, only 47 permanent inhabitants remain on the island, most of which are descendants of the mutineers of the HMS Bounty in 1789.

Over its history of human settlement, the islands have been visited by National Geographic twice – the first time in 1957 when explorer Luis Marden set to uncover the wreckage of the HMS Bounty, and once again in 2012 when Pristine Seas set out to assess the health of the marine environment surrounding the secluded islands.

The location of the Pitcairn Islands. Map by National Geographic

The voyage in 2012 was documented and released worldwide as a documentary titled ‘Sharks of Lost Island’.

Led by Pristine Seas founder and National Geographic explorer, Dr Enric Sala, and terrestrial explorer Michael Fay, a team of marine ecologists and filmmakers undertook a month-long expedition to the Pitcairn Islands. Over the course of the trip, over 450 hours were spent underwater across 384 dives to assess the state of the underwater ecosystems.

The survey found an abundance of highly diverse and heathy coral habitats. Sharks were focused on as an indicator of ecosystem health and were found in all surveyed areas except off the coast of Pitcairn Island itself.

Discovery after discovery

Deep-sea explorations of 40 Mile Reef revealed coral species that have adapted to living in waters almost twice as deep as conventional corals. This is likely due to the exceptional water clarity of the Pitcairn archipelago.

The team used drop-cam technology to reach depths of 600 m and in the process found eight entirely new species of fish, the clearest underwater visibility ever measured in the Pacific and the deepest known living plant – a coralline alga surviving at 382 metres below sea level.

As the marine world was being thoroughly explored, Michael Fay turned his attention to the terrestrial life and made some disturbing discoveries.

Whilst surveying petrels on Ducie island, Michael Fay discovered “dead bird after dead bird”. As it turns out, the introduction of an invasive plant species has led to the death of countless freshly fledged petrels by entangling them in its sticky goo and rendering flight impossible.

It is unknown how the invasive species arrived at the island, whether through human exploration or on the birds themselves, but one thing is for sure: the island is suffering.

A juvenile petrel after a failed flight attempt. Picture by Enric Sala

In addition to the gruesome discovery on Ducie island, an investigation on Henderson Island (which accounts for 86% of the archipelago’s land area) uncovered a pest of another kind: rats. The Polynesian rat has been introduced to almost every island in the Pacific as a result of Polynesian exploration over the last millennium and has led to countless ecological disasters.

As such, Henderson has had an extensive “deratification” effort through the use of rat poisoning. However, whilst exploring the island’s prehistoric forest, Mike Fay spotted a surviving individual, demonstrating the failure of the pest control efforts.

The Journey

All of these discoveries made watching Sharks of Lost Island engaging and exciting. As I was introduced to members of the team, I could clearly tell that each of them had a genuine passion for their research and the chance to explore the Pitcairn Islands was a dream come true for them.

When the drop-cam footage is being analysed for the first time, the whole crew gathers round and emanates excitement as a deep-sea shark casually glides into view. When the documentary was over, I found myself eager to visit the Pitcairn Islands and make some discoveries of my own.

Although being released way back in 2013, I was delighted to find the majority of the documentary still more relevant than ever. Coral reefs are among the most threatened of all ecosystems and protecting them has received more and more attention in recent years. In addition to this, the threat of invasive species as well as the excess of plastic pollution on some of the most isolated land masses in the world, truly puts our practices as a species into perspective.

In spite of this, I felt that some portions of the documentary left a lot to be desired. I was disappointed with the lack of ecological explanations for the spectacles I was shown. The subject of the title was barely given the spotlight, and despite being referred to as “indicators of a healthier reefs” the reasons for which were not given. I found myself asking, “where are the sharks?”

A whitemouth moray eel and a whitetip reef shark. Picture by Enric Sala

For context, sharks (or any other top predator for that matter) provide population control on lower trophic species. By reducing the number of coral grazing fish, the corals themselves are given a chance to grow and a whole ecosystem collapse is avoided. This was not mentioned once.

In addition to the lack of context, I found myself growing concerned with the show’s potential impacts on the Pitcairn ecosystem. Good intentions aside, the show ended with the Pitcairn Island populace speaking of plans to promote tourism. This harbours the potential for even more invasive species and contradicted the segments with Michael Fay warning against the introduction of alien species.

The Pitcairn population did, however, agree to introduce a marine reserve and in 2015, the British government established the Pitcairn Islands Marine Reserves which remains one of the largest marine reserves in the world. The research shown in this documentary has definitely paved the way for this legislation.

The Verdict

Sharks of Lost Island is a thrilling documentary that instils excitement into any aspiring marine biologist. By actively working on their mission and letting us get to know the team, watching this documentary invokes the sense of exploration and makes the Pitcairn Islands a desirable destination.

But does it do this too well?

The establishment of the Pitcairn Island marine reserve in 2015 gives us hope that the beautiful underwater world, of which we were given a glimpse of in 2013, will remain that way. But the threat of invasive species remains a significant one. Perhaps by bringing these remote islands to light, we have opened them up to a myriad of potential dangers.

Sharks of Lost Island is now streaming on Disney+

Written by Lucas King