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Norfolk Island's Reef

Discover a fragile paradise – Norfolk Island's beaches, lagoons and coral reef
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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.

This blog is rated in the Top 20 Coral Reef Blogs in the world.

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Spotted porcupinefish, Diodon hystrix

A case of mistaken identity?

July 6, 2021

There have been biting cold winds blowing directly from the east for most of the last week, moving around to the north in the last couple of days, and quite a bit of rain. This has made it rather brisk getting out of the water, but when in, the conditions have been sublime, particularly in the shelter of Emily Bay. Fantastic glass-like viz has made exploring the sandy shallows a lot of fun.

On the Lone Pine side of the bay, since at least 17 June (when I first spotted it), a solo convict surgeonfish, Acanthurus triostegus, has been hanging with the group of blackspot sergeant, Abudefduf sordidus that inhabit the area. I do sometimes wonder what attracts a fish on its own like this to join up with a school of fishes that look slightly similar in shape, colour and markings. Safety? Mistaken identity? Who knows?

View fullsize Convict surgeonfish - Acanthurus triostegus
Convict surgeonfish - Acanthurus triostegus
View fullsize With blackspot sergeants - Abudefduf sordidus
With blackspot sergeants - Abudefduf sordidus
View fullsize Spotted porcupinefish - Diodon hystrix
Spotted porcupinefish - Diodon hystrix
View fullsize Spotted porcupinefish - Diodon hystrix
Spotted porcupinefish - Diodon hystrix

A small spotted porcupinefish, Diodon hystrix has been hovering out in the open in the same spot on the Salt House side of the bay since at least 28 June. These fish are generally nocturnal and solitary, and, although I have heard that they will be inquisitive and follow divers around like puppy dogs, here on Norfolk Island I find they are generally shy and tend to retreat when you get too near. When you do see them, they are often under rock ledges or in caves. Again, I’m not sure what is going on that this one should be so exposed and not mind remaining there while I photographed it. These fish are broadcast spawners, ‘meaning both sexes mate with many different partners during spawning events’.

I have one old scarred porcupinefish that I visit regularly in his cave. More often than not he comes to the front of his cave and peers out at me. I give him a thumbs up and head on my way.

Emily Bay has a wonderful raft, used by generations of adults, teens and children. It is synonymous with summer and fun. Each year it gets hauled from the water, cleaned, repaired and popped back, usually over the wintertime. Last year, the raft was in a very poor state of repair and, consequently, the Norfolk Island Regional Council’s maintenance workers rebuilt it from scratch.

Emily Bay’s iconic raft

This new version is a different design to the one we had before; now it sports flotation tanks beneath it. I understand these may have been put there to prevent children swimming under the raft and surfacing in the air pocket created by the rafters, but I am not entirely certain. Whatever, I am sure it seemed like a good idea.

Over the years, the raft has provided shelter beneath its timbers for a thriving fish nursery. Beneath the raft was an amazing sight, teeming with fry. I have photos of it before the rebuild and since. I wanted to give it a full year before I made any comment on the new design, but I can say now, for whatever reason, the fish simply have not used the raft that much since it was rebuilt. A couple of times I’ve seen small schools (as in tens of bubbas rather than hundreds), but within a day or two these have disappeared, hunted by the trevally and other fish. I witnessed trevally sweeping in a pack under the raft as they hunted for food. (Below is a video of how they operate, although this was not filmed at the raft.) The small fry were gone in no time. With the previous design they were able to quickly retreat up between the rafters, out of the way of the fast-moving trevally. Now, sadly, there is nowhere for them to go.

I should also add here, I am not criticising the new design or the thought behind the improvements. I am sure it was done with the best of intentions, but the consequence is that we have had very few babies growing up under the new raft. Something to consider.

View fullsize 22 April 2020
22 April 2020
View fullsize 22 April 2020
22 April 2020
View fullsize 3 May 2020
3 May 2020
View fullsize 16 April 2021
16 April 2021
View fullsize 5 May 2021
5 May 2021
View fullsize 16 May 2021
16 May 2021

Trevally, Pseudocaranx sp 'dentex', on the hunt for newly hatched fry, Emily Bay, Norfolk Island

← Winter in Norfolk Island's lagoonsMid-winter fabulousness →
Featured
No seagrass, but plenty of turtles
September 13, 2026
No seagrass, but plenty of turtles
September 13, 2026

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.

Read more →
September 13, 2026
Watching El Niño from Norfolk Island
September 6, 2026
Watching El Niño from Norfolk Island
September 6, 2026

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.

Read more →
September 6, 2026
What the world’s reefs are telling Norfolk Island
September 2, 2026
What the world’s reefs are telling Norfolk Island
September 2, 2026

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.

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September 2, 2026
When the map changes
August 25, 2026
When the map changes
August 25, 2026

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.

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August 25, 2026
Endemic, native, undescribed – what do these words actually mean?
August 24, 2026
Endemic, native, undescribed – what do these words actually mean?
August 24, 2026

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.

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August 24, 2026
What’s grazing in the green stuff?
August 16, 2026
What’s grazing in the green stuff?
August 16, 2026

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?

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August 16, 2026
The clam beneath Emily Bay
August 8, 2026
The clam beneath Emily Bay
August 8, 2026

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.

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August 8, 2026
Reflections of an accidental marine scientist
August 1, 2026
Reflections of an accidental marine scientist
August 1, 2026

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.

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August 1, 2026
From ridge to reef: unpicking the Waterway and Wetland Strategy
July 24, 2026
From ridge to reef: unpicking the Waterway and Wetland Strategy
July 24, 2026

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.

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July 24, 2026
Reef reality in pictures
July 13, 2026
Reef reality in pictures
July 13, 2026

Let the pictures do the talking. This is the reality on Norfolk Island’s reef today, laid out in a two-minute video.

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July 13, 2026

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