Fiji's mystery island: midden or muddle?

B.M. Allsopp

1 day ago

3 min read

Updated: 12 minutes ago

A mangrove forest in Fiji — Mangrove forest in Fiji (*Fiji Times*)

Death on mystery island

I've written seven fictional mysteries set in Fiji, so I'm intrigued by a true Fijian mystery that popped up in the scientific news recently. This mystery is a cold case from over a thousand years ago, involving the mass slaughter of countless thousands of tiny victims - edible shellfish. There's plenty of physical evidence remaining at the crime scene, now hidden in a dense mangrove forest on the west coast of Vanua Levu, Fiji's second largest island. The evidence consists of immense quantities of shells. But whether the creatures died by tragic accident or by murder can only be discovered by scientist detectives and their forensic resources. Professor Patrick Nunn, who spent 25 years at the University of the South Pacific (USP) and his team considered all the evidence, put two and two together, and now have a prime suspect for the deaths on Fiji's mystery island.

Professor Patrick Nunn - lead detective

When I was at USP 20 years ago, Dr Nunn was Professor of Geography, an inspiring teacher and an internationally respected researcher on the effects of sea-level changes on landscape evolution in the Pacific. Dr Nunn is now Professor of Geography at the University of the Sunshine Coast in Queensland. With nearly 400 research articles to his name, he is uniquely qualified to lead this investigation.

Map of the shell island (brown) in the mangroves (green) off Culasawani on Vanua Levu's west coast (*Geoarchaeology*)

Fiji's mystery island - discovery of the bodies

During a coastal survey of Vanua Levu in 2017, a large mound of compacted shell debris was noted in the mangrove forest near Culasawani. Professor Nunn's team from USP returned in 2024 to conduct a systematic dig and found that the mound was actually an island. They examined four test pits and 20 narrow core samples taken from different areas of the shell island, which covers about 3,000 square metres (see map).

Middens and muddles

Midden islands are created by by people through the accumulation of discarded shells, bones, and everyday debris over time.

Muddle islands are natural deposits left by a tsunami or large wave.

The researchers had to decide if this shell island was a midden or a muddle.

Forensic evidence

Researcher explores the surface of the midden island off the coast of Culasawani, Fiji — Researcher Michelle McKeown of University College Cork explores the surface of the midden island off the coast of Culasawani, Fiji. (Patrick Nunn)

Radiocarbon dating of clam shells in the samples showed they are about 1,200 years old. As humans colonised Fiji 3,500 years ago, it's plausible the shells were gathered by people living nearby. But no fragments of stone tools or animal bones have been found, which could point to the island being a muddle.

However, all of the shells belong to edible species, which would be unlikely if the mound had been formed by a natural event such as a tsunami. What's more, pottery shards were found among the shell debris, indicating human presence.

Death on mystery island - the verdict

While it's highly unlikely the island was a village site, a wave of early settlers who arrived in the Fiji Islands around A.D. 760 may have formed the shell-dense island as they processed edible shellfish here before taking them home to eat. The processors may even have packed the flesh in brine-filled pots for trading. This production may have continued for a few hundred years. However, the scientists plan to look for settlement sites on nearby Culasawani that could be linked to the shell island. If the mystery island is confirmed as a midden island, then this is the first to be recorded in the South Pacific east of Papua New Guinea. Quite a find!

Listen to Professor Nunn's interview about 'mystery island' on ABC Radio's Pacific Beat. https://www.abc.net.au/pacific/programs/pacificbeat/midden-island/106595722
Read the full article by Professor Nunn and colleagues:

Nunn, P. D., F. R. Thomas, M. Fong-Lomavatu, et al. 2026. “ Shell-Dense Island Off Culasawani, Vanua Levu Island, Fiji: Midden or Muddle?.” Geoarchaeology 0: e70052. https://doi.org/10.1002/gea.70052.

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