The sea-wolves of Emily Bay — 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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Another underwater drama has been playing out in the shallows of Emily Bay over the last few weeks.

At the end of November, I photographed a mass of newly hatched fry gathered around what looks like an old oil drum. Over time they’ve grown bigger; In the following weeks I saw some of them in open water having left the safety of the drum's coral crevices, and other refuges, to head for the reef.

Attracted by the easy pickings, I then watched as the silver trevally – Pseudocaranx sp 'dentex' – arrived. Like a sleek pack of wolves they swept around, in and out of the drum scooping up whatever they could. The fry shrank back, huddling together, trying to stay out of the maelstrom and away from so many hungry mouths.

The fry’s numbers have been depleted considerably by these regular visits made by the insatiable trevally, but still some survive and are growing bigger by the day. They are mainly juvenile big eyes – the Norfolk cardinalfish, or Ostorhinchus norfolcensis – but there are also some juvenile smoky pullers – Chromis fumea – in their number.

Last week another visitor arrived on the scene. This time a lone blue trevally – Carangoides ferdau. It's agonising to watch, but then you also have to admire these sleek streamlined hunters as they speed around the tight corners, swooping on anything in their path.

Blue trevally - Carangoides ferdau

Silver trevally - Pseudocaranx sp 'dentex'

You probably don’t realise it, but this daily drama unfolds right by your feet as you wade into the peacock-blue shallows of Emily Bay for a swim.

As an aside, in previous years, much of this action happened beneath the raft, where there was a fantastic underwater 'cave' for the babies. The new raft has very little space beneath its rafters because of the way it has been constructed. And of course the weed hasn't yet had a chance to grow back as luxuriantly as it was before. So far this year, very few fish have decided to make it their nursery. It will be interesting to see if that changes as the weed grows. I'll be watching with interest.

February 2020 - beneath the raft

January 2021 - beneath the raft

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.

June 28, 2026

The red seaweed behind low-methane beef

A small red seaweed on Norfolk’s reef has become part of a much bigger story. Asparagopsis taxiformis can look like a delicate red feather duster or, at another stage of its life cycle, like a tiny cottony pom-pom. It is beautiful, easily overlooked, and now being used in the cattle industry to help reduce methane emissions. This post looks at the reef oddity behind the low-methane beef story – and why repeated local observation can be more useful than it first appears.

June 20, 2026

From coral scar to aatuti farm

Aatuti are bold little algae farmers, but how does one of their farms begin? Over the past year, I have been following several coral patches as small white scars became algal footholds, then larger defended patches. I still cannot say what caused the first wounds, but the photo sequences show something fascinating: on a reef where algae is already gaining ground, even tiny changes on the coral surface can become part of a much bigger story.

June 15, 2026

Norfolk’s water quality – when action is reported as outcome

A recent Australian Government media release presents investment, monitoring and catchment works as progress on Norfolk Island’s water quality. Some of that work is useful, and some of it was badly needed. But activity is not the same as proven improvement. This post looks at Kingston sewerage, wetlands, cattle, acid sulfate soils, groundwater and reef health, and asks whether Emily Bay and Slaughter Bay are actually being better protected.

June 14, 2026

How surgeonfishes got their name

Surgeonfish are named for the sharp little scalpels near their tails, but on Norfolk’s reef their more useful work happens at the other end. Pencil surgeonfish, bluespine unicornfish and their relatives help browse algae across the reef – a small daily job that becomes very valuable on an algae-rich lagoon reef like ours.

May 28, 2026

A shrimp storm

While setting my research cams last week, I swam into what looked like an underwater snowstorm. It appeared to be the aftermath of a mass moulting event, with large numbers of tiny, translucent shrimp-like exoskeletons drifting together near the surface.

Kingston dredging: what happens when a reef does not fit the framework

This correspondence with DCCEEW is about more than one dredging proposal. It is about what happens when an ecologically distinctive place is assessed through standard tools that do not always make its most important values easy to see. I am publishing it here because that is something we need to be aware of, both on Norfolk Island and more broadly in Australia.

May 24, 2026

Kingston dredging: the project advances, the questions remain

Kingston dredging is edging closer, and the paper trail is growing. This post brings together earlier correspondence with the Department and the latest media release so readers can see what has been asked, what has been answered, and what still remains unclear about the project, its rationale, and the protections proposed for the reef.