A pair and a spare – snubnose darts on Norfolk Island's reef

Out on A Swim

‘Out on a swim’ is a coral reef blog that tells the stories of the characters who live under the waves and what has caught my eye when ‘out on a swim’ in the lagoons of Norfolk Island. It is also a record of the difficulties Norfolk Island’s reef faces, like many others around the world, as a result of the poor water quality that has been allowed to flow onto it.

This page shows the most recent blog posts. For the complete catalogue, visit the ‘Out on a swim index’ page.

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DAY 23 – MARCH FOCUS ON NORFOLK ISLAND’S REEF

Norfolk Island’s reef is small and intimate. We can count the numbers of some species of fish on one hand, which is how I can watch the comings and goings with interest as I swim among them. I love the stories that play out and which I get to witness, and these snubnose darts (Trachinotus blochii) are a case in point.

There are a pair of them that always hang out together. I have images going back to March 2020 of the same individuals, and I can tell they are the same ones because one of them has a slight nick out of the top fork of its caudal fin. They are what I call a ‘sometimes’ visitor. They come. They go. But more often than not they seem to reappear in March and disappear in November.

I have no idea what sex they are, but I do know that in mid 2021 they were joined by a much larger snubnose dart, which I assumed was a male. He was an impressive specimen, much larger, with a streamlined body of mirrored metallic silver. He stayed with the pair for a month or so, although I can’t tell you if he was with them 24/7 or if he came and went as the mood took him.

The juvenile trevally, smaller than my little finger

By October 2021, the pair were once again on their own, happily hanging in their favourite spots, either at the Lone Pine end of Emily Bay, or in the shallows of Slaughter Bay (although occasionally you will see them swimming between these two places). This time they were joined by a tiny passenger, a juvenile (baby) trevally. I’ve put a ring around him in the photo because he is so hard to see otherwise. If you click on the photo, it will enlarge.

I like to take credit for that baby’s introduction to the pair. The baby trevally had attached himself to me, swimming beside and around me for more than half of my hour-long swim. I am sure anyone who was watching from the shore thought I was demented as I spun around trying to capture him on film, so closely was he glued to my side.

I probably represented food or protection of some kind, but even so, it was quite the privilege to connect with this busy, happy little thing as he darted in and out of my field of vision. At the end of my swim, I found the two resident snubnose darts close to the Lone Pine end of Emily Bay. My little companion transferred his affiliations in a quicksilvery flash!

Fast forward to last week, in March 2023, and there were the pair of besties back foraging in Slaughter again. And there with them was a third wheel. A juvenile (teenager) trevally.

A tiny trevally inside the circle, October 2021

A trevally with the two darts, March 2023

The much larger (male?) snubnose dart with the two smaller residents in August 2021

I wonder? What do you reckon?

He is quite a bit bigger than before, but could it be the same one, 18 months later? The three of them circled around me a few times as I took their photo and then swam off.

Maybe I am being fanciful. But I do hope it was the same little trevally, because it certainly makes a delightful story.

There’s a lovely postscript, too. A week ago I spotted a young snubnose dart on its own in Emily Bay. Is it the progeny of the tryst made back in mid-2021 when the larger dart gatecrashed our lagoon, seemingly to court our two ‘sometimes’ residents? Who knows.

Why are there always so many more questions than answers?

September 18, 2026

In a nutshell – where I stand on the proposed Norfolk Island Marine Park

I support the proposed expansion of Norfolk Marine Park and its renaming as Norfolk Island Marine Park. There is much to welcome – strong offshore protection, no mining, and recognition of the importance of sustainable local fishing. But I also have some reservations. Why does Cascade need to be removed from the Marine Park at all? How will more than 430,000 km² actually be monitored and enforced? How do we make sure Norfolk people have a genuine role in management? And, above all, how do we ensure that the enormous new park does not draw attention away from the small, stressed reef immediately beside us?

September 13, 2026

No seagrass, but plenty of turtles

Norfolk Island does not have seagrass, although one of our most conspicuous green algae is often mistaken for it. Feather and grape Caulerpa can both form striking patches across the lagoon. I take a closer look at what Caulerpa actually is, why it is so easily confused with seagrass, and where our green turtles fit into the story.

September 6, 2026

Watching El Niño from Norfolk Island

El Niño is strengthening across the Pacific, but that does not tell us exactly what the coming months will bring to Norfolk Island. After a long wet spell, I am watching our rainfall and water supplies more closely again – and, underwater, keeping an eye on sea temperature, algae, coral recruits and the fish that turn up on the reef.

September 2, 2026

What the world’s reefs are telling Norfolk Island

Two major new coral reef reports carry a clear message for Norfolk Island: reefs can recover when pressures ease, but the time available for recovery is shrinking. Norfolk Islanders were raising concerns about water quality, runoff and the health of Emily and Slaughter Bays nearly forty years ago. Today we have much better science, a changing climate and a far clearer understanding of how closely the catchment and reef are connected. This article looks at what that means for water quality, long-term monitoring, dredging and how we manage Kingston from land to sea.

August 25, 2026

When the map changes

A fish once thought to belong only to Norfolk turns up elsewhere; another appears here hundreds of kilometres beyond its known range. Cardinalfishes and a Sabre squirrelfish show how our maps of species distributions are revised.

August 24, 2026

Endemic, native, undescribed – what do these words actually mean?

A Norfolk chromis that turned out not to be Chromis fumea, a blenny found nowhere else, and a tiny goby that may not yet have a name. A look at what we mean by native, endemic, undescribed and newly described – and why scientific names sometimes change.

August 16, 2026

What’s grazing in the green stuff?

A proliferation of Bryopsis on the reef has brought some beautiful little underwater grazers with it. I follow the trail from sap-sucking sea slugs and egg masses to a bigger question – why is there so much Bryopsis around at the moment?

August 8, 2026

The clam beneath Emily Bay

I’ve seen the beautiful shells of Laciolina chloroleuca in Emily Bay for decades, but I’d never really stopped to wonder where the living animals were. It turns out they may be buried half a metre beneath the sand. A closer look at an easily overlooked clam, its extraordinary shell markings, and the hidden life beneath our lagoon.

August 1, 2026

Reflections of an accidental marine scientist

What I thought would be a steady plod towards retirement, with plenty of time spent nursing grandchildren, was abruptly upended exactly six years ago today. This is the story of how an environmental catastrophe changed the course of my life – and led me to reinvent myself. It is a reflection on how, and why, I became an accidental marine scientist.

July 24, 2026

From ridge to reef: unpicking the Waterway and Wetland Strategy

Norfolk Island’s draft Waterway and Wetland Strategy will guide work for the next ten years. I support its intent, but it needs to be clear, practical and measurable – joining the dots from ridge to reef so we know whether public money is improving water quality and helping the reef.