Science at the far end of the world

Starting a project in one of the most isolated regions of the world takes an uncommon kind of grit. I ask Naiti to describe what learning to work here has been like. Her response is measured: ‘Unique, expensive, unknown, uncertain.’ The weather, a growing list of field-work expenses and her reliance on local fishermen for access to their boats are persistent challenges. She first visited Motu Motiro Hiva in 2015 to tag sharks and fishes like Seriola lalandi, as well as to take genetic tissue samples.

The Save Our Seas Foundation has been helping to sponsor her work with BRUVs and in September and December 2016 she deployed her first cameras around Rapa Nui. The BRUVs film different species that swim into the camera’s field of view, giving scientists a record of the composition of the community and the relative abundance of each species. The cameras are deployed from a boat and fish are attracted by the scent from a bait canister attached to the system. Naiti’s BRUVs are pelagic, which means that instead of being deployed on the sea floor, the cameras hover at about 10 metres from the surface. This is a non-extractive way of recording the highly mobile, often diver-shy predators that rule the open ocean.

Adversity makes Naiti organised. ‘Equipment and tools are expensive and really basic. These limitations mean I have to try to buy everything I might need in advance. Sometimes they’re things I’ve never used before.’ So what keeps her committed to this capricious place? ‘Magic,’ she replies.

Talking to Naiti, a region that I’ve only encountered in well-thumbed Lonely Planet guides leaps to startling technicolour life. My imagined Rapa Nui, dominated by the moai statues looming large in a windswept volcanic landscape, now extends well below the blue expanse that dwarfs the island. ‘My favourite memory of it is actually from being on the water, looking down. Two years ago I worked on a Chilean Navy vessel that was travelling from the continent [South America] to Easter Island. Once we arrived at Salas y Gómez, I saw the cleanest water ever. There was no wind, so the water shimmered bright. We got into a smaller boat and threw the fishing line into the water to start our tagging work. In that moment, we realised we were totally surrounded by sharks and bony fishes. It was the perfect moment: the silence, the colour and the ocean.’

On a computer screen, a map of this region glows red, yellow and blue. This is how a satellite sees swathes of tiny marine plants called phytoplankton from space. Their populations blink back from the screen in colour codes that scientists use to model their abundance. High concentrations gleam in warm colours; low abundances in blue hues. Plankton, the building blocks that underpin the marine food chain, glow nutrient-rich red near the Chilean coast and yellow near the equator. By contrast, the expanse of water around Rapa Nui glimmers blue. Its waters are clear, but much of the Pacific Ocean here is nutrient poor. In the South Pacific Subtropical Gyre, the great swirling ocean circulation that dominates this region, phytoplankton are found deeper, at about 150 metres.

‘When you live on an island, you’re directly connected to the sea,’ says Uri Erisa Tuki, a local craftswoman, in the documentary Voices from the Sea. The problem is that the impacts from local fishing are now amplified by threats from the outside world. New colonists from a modern world gone consumer-crazy wash ashore as plastic pollution, while illegal, industrial-scale fishing vessels have quickly sniffed out the most vulnerable underbelly of Rapa Nui: its isolation.

The depletion of fish populations elsewhere means that vessels, equipped with new technology, creep progressively further afield in search of fish stocks to exploit. That these fish are in another country’s territorial waters is an obstacle only on paper. The Chilean Navy is responsible for enforcement, but the vast distances mean that much of this illegal fishing happens opportunistically. ‘The Subtropical Gyre also pulls the garbage towards the island,’ says Naiti. ‘The islanders try to manage the trash as best they can, but it comes from the sea. In one of my BRUVs videos, I saw a shark entangled in plastic.’

Naiti explains that for the scientists of ESMOI, a baseline survey is a step towards understanding the patterns of marine life in the region so that they can better protect it. ‘The Chilean government protected the waters around Motu Motiro Hiva because it’s really special. Its isolation means that there may be undiscovered species there. Yet the government protected the area without knowing too much about what’s going on in it. We’re trying to gather information so that we can expand the borders, or create better ones, for marine protection, while trying to figure out how to protect Rapa Nui too.’

That predators abounded around Rapa Nui is evidenced by petroglyphs depicting marlin, tuna and sharks. They hint at the past abundance of these hunters, as well as their importance to ancient Rapa Nuians. Colleagues initially advised Naiti that her quest for sharks would yield no results. She remained true to her convictions: previous surveys were diver-based and many sharks steer clear of divers. ‘When I started working, a lot of colleagues said there are no sharks there. I said, yes there are. The fishermen are saying that they see sharks every time they go out. They have to be somewhere!’

Fishermen spoke of the ubiquitous Galápagos shark, the tiger sharks that arrived in summer and of mako and blue sharks. They pointed out on her study map where they saw sharks and she designed her survey to target these areas. Naiti describes the heart-stopping moment when her first shark swam into view on video: ‘A lot of people told me I was wasting my time. When I saw the first shark, I got super excited. My dream was coming true! For the first time, we have a scientific record of these sharks around this island.’