Phoenix Islands Reef Report
Health of the Phoenix Islands Reefs

The Phoenix Islands are a group of eight islands just below the equator and just east of the Date Line. They belong to the Republic of Kiribati whose government is centered in Tarawa on the western Gilbert Group. Kiribati also owns the Line Islands to the east of the Phoenix Islands.

We concentrated our study efforts on Kanton Island (also known as Canton), taking photographic transects and a GPS outline of a section of reef. Additionally, we made survey dives for fish and coral at the other islands listed below. At Kanton our area of study was three miles to either side of the Heraclitus' anchorage, on the western side of the island where we were afforded protection from wind and swells.

Dates of Studies:
Sydney (Manra) Island: 22nd Nov 2004
Enderbury (Rawaki) Island: 24th Nov 2004
Kanton (Aba-Riringa) Island: 26th Nov – 10th Dec 2004
McKean Island: 14th Dec 2004
Gardner (Nikumaroro) Island: 16th – 19th Dec 2004
Previous Studies:

The Phoenix Islands were very well studied in June/July 2000 and again in June/July 2002 by teams of scientists on expeditions organized by the New England Aquarium in Boston. Their reports describe:

‘Phoenix Island reefs provide a model of what atoll reefs in this part of the Pacific Ocean are like with minimal human disturbance.’
‘Overall coral reefs appeared in near-pristine condition with no evidence of human influence.’
‘reefs in an overall excellent state of health’
‘threats to corals were quantified during surveys but were negligible compared to the influence of physical disturbance from waves. The most common evidence of coral stress was the presence of partially bleached colonies of Pocillopora spp. However at low levels that can be considered normal for healthy coral communities. No evidence of a recent bleaching event was seen though it is possible that dead colonies from the worldwide bleaching event of 1997-98 could not be recognized due to their age and colonization by algae.’
‘further evidence of the health of coral communities at Kanton was the near absence of signs of threat to corals, with only algal overgrowth recorded for two coral colonies in the four sites surveyed.’

Kanton Island

26th Nov - 11th Dec, 2004

Reef type:

Fringing reef and lagoon floor inside atoll

Average Water Temperature:



Less than 5% of the living reef is currently affected by bleaching


There were no visible signs of disease.


Very variable – from just a few metres to about 15 metres but generally pretty low, even on the fringing reef

Crown of Thorns:

One COT sited on fringing reef

Geography/ History:

There are no permanent inhabitants of the Phoenix Islands but a small community is sent to Kanton from other islands of Kiribati and there are reports that a community of about a hundred people was established on Orona (Hull) Island in 2001. The land of Kanton Island covers 3 ½ square miles. It was discovered by westerners in the early 19th century as one of the richest sperm-whaling grounds in the South Pacific and was named after an American whaling ship that wrecked there in 1854. Guano was extracted from Kanton as well as some of the other Phoenix Islands for a while. During World War II, Kanton was a US air base. After the war until 1958, the airfield was used as a refueling station for transpacific flights - the runway still remains on the north side of the island, close to the village. There is also a seaplane landing strip still clearly marked in the lagoon. From 1960-68 the island was used by NASA as a satellite tracking station. The Air Force used Kanton as a base for missile testing in the Pacific, finally closing it down in 1976. In 2001, a foreign fishing boat was allowed to harvest sharkfin by longlining around Kanton, Orona, Sydney and Phoenix Islands.

Reef Topography:

Kanton is an atoll with just one entrance to the lagoon within. The current in the pass can reach more than 10 knots when the tide is turning. We explored the barrier reef on the west side of the island where the sea was calm enough for us to dive. The northwest and southwest points of the island have large breakers. The lagoon is very shallow (less than 10 metres) around the entrance and just behind the small island that lies inside the entrance. There are sticks in the water marking an old seaplane landing site across the lagoon. We followed these sticks to explore the interior of the lagoon – the depth didn’t vary much on this transect. Around the entrance there is dense coverage of hard corals (now dead) but the interior of the lagoon is sand-bottomed with small bommies. The visibility within the body of the lagoon was less than a metre and the water was very green.


In Kanton, the corals are in an abysmal state, accentuated for us by our expectations of seeing pristine reefs.

The fringing reef has very low live coral coverage (estimate of less than 15%). There is a prevalence of algal overgrowth from macroalgae, encrusting coralline algae and, to a lesser extent, filamentous algae. There are also large areas of rubble, which is to be expected from storm and surge. It is very easy to see what has been growing on the reef in terms of the genera of hard coral.  The structural form of the colonies remains, but the living matter has disintegrated.

Inside the lagoon, it became obvious that these reefs have mostly died in one fell swoop. The reports from the New England Aquarium expeditions describe vast areas of thriving table Acropora colonies. These colonies still stand today, but as dead skeletons, some of them toppled over. There were a few living Millepora and Porites colonies scattered throughout the lagoon, but the majority of what we observed was dead and covered with filamentous and coralline algae. There are still fish swarming the lagoon, but against a lifeless backdrop.

In July 2002, while the New England Aquarium team was here, water temperatures were higher than normal. NOAA reported the Phoenix Islands to be in a ‘hot-spot’ of the Pacific Ocean. Bleaching began, notably in the lagoons of Kanton and Orona, and mostly to the genera Echinopora, Goniastrea and Acropora. The scientists left just two weeks into the hot-spot but it continued for three months. The most likely explanation for the death of these reefs is a mass bleaching event in 2002.


The fish populations at Kanton were extremely diverse and extremely high (as at all of the islands we studied). The marked difference between Kanton and the other islands was the lower number of sharks here, due to the shark finning efforts in 2001. The most prevalent predator was the red snapper of which there were more than at the other islands. One very interesting sight was a fully grown napoleon wrasse that had had its tail bitten off. Its movements were unimpaired – it maintained the bumbling slow pace of all other napoleon wrasses.

We had many experiences with manta rays, the most spectacular being at the mouth of the pass where they gathered on an incoming tide to feed, in schools of up to 20.

Despite the degenerated condition of the corals, the fish populations are still thriving. But the question arising is whether or not the reefs can retain these populations and the balance between them if the corals themselves do not recover.

The waters around all the Phoenix Islands, but especially Kanton, were full of schools of tuna, barracuda and other pelagics. We sighted a great number of turtles, mostly green turtles, and we twice observed mating turtles on the surface.


We encountered pods of bottlenose dolphins at both Kanton and Nikumaroro Island. At the latter, we also met a pod of false killer whales which attacked and killed a marlin.

Sydney Island


22nd Nov, 2004


Sydney is an uninhabited island with dense vegetation on it. We made exploratory dives here to gauge the state of the reefs. There were high numbers of sharks at one site, especially juvenile grey reef sharks but fewer at the northern tip. The corals are in poor condition, predominantly covered in encrusting coralline algae. Acropora and Pocillopora, the predominant corals in the majority of the previous study sites across the South Pacific were largely absent in Sydney.

We observed an increase in the number of seastars and clams compared to dives in Tokelau, Samoa, and the Cook Islands.

Enderbury Island


24th Nov, 2004


Enderbury has previously been exploited for phosphate mining and was a military base but is now uninhabited. The island reeks of guano from a few miles away on the leeward side and is smothered by birds. In fact, we had some close encounters with frigate birds – when ascending from dives and using blow-up sausages to attract attention and while fishing, the frigates would descend and peck at either sausage or freshly caught fish or the hand holding either.

Once again, the fish life was incredible. Black tip, white tip, and grey reef sharks surrounded the divers as they entered the water. The most predominant fish was clearly the red snapper. Here the corals are suffering the same plague of encrusting coralline algae, and there were also large amounts of macroalgae, especially lower on the slope where it was encroaching upon branching colonies to the extent that only the tips of the branches were exposed. Many coral colonies were also severely affected by invertebrates including boring clams and christmas tree polychaetes. Hard coral cover ranged from 15% In the shallow zones above 15 meters to 40% 15-25 meters.

McKean Island


14th Dec, 2004


McKean is a very small sand island. There is a wreck on it – a large fishing boat that has run straight up onto the shallow reef shelf. It looks fairly recent and very dramatic.

The shark population is doing fine here – healthy numbers of grey reef sharks, and whitetips (a few blacktips). But there also seemed to be a much higher density of red snappers. We came across a gathering of pufferfish under a ledge – two New Guinea puffers and eight yellow puffers, all flapping furiously together.

Here there was a slight upturn in the number of live coral colonies.

Gardner Island


16th - 19th Dec, 2004


Gardner is another uninhabited island, with rumours abounding that it is the island where Amelia Earhart met her fate in a crash landing. We had read of having juvenile blacktip reef sharks swarm around wading feet in the lagoon. We did see some baby blacktips, but not to the degree we had expected or hoped. But there were plenty of blacktip reef sharks on the fringing reef, more than at any of the other islands. Also grey reef sharks and whitetip, plus several encounters with manta rays.

Here the fish were so prolific that divers would disappear behind clouds of them – enormous schools of surgeonfish, unicornfish, drummers, snappers, jacks, producing constant streams of movement. The corals were the healthiest and most diverse of all the islands – with genera represented here not seen at any of the other islands eg. Plerogyra.

We encountered bottlenose dolphins, false killer whales which devoured a marlin right beside the zodiac, and plenty turtles. Overall, Nikumaroro was the most vibrant reef of the islands we explored in the Phoenix, but it was by no means unscarred by what has afflicted all the others.

Reef Report
Vitareef Data
Coral& Fish ID
GPS Data