Kermadec Islands - images of
fishes By Dr J Floor Anthoni, 2002
The fishes of the Kermadec islands comprise
a mix of species from the tropics (north), the temperates (south), the
subtropics (west: Norfolk, Australia; east: Rapa and Easter Island), and
endemic species (Kermadecs). About 2% of species are found only here, which
makes these islands a precious hotspot of biodiversity. Due to their severe
isolation, several species on the Kermadecs have evolved into unique forms,
found only here.
Due to their isolation, several species on the Kermadecs have evolved
into unique forms, found only here. Living in a very small spot, surrounded
by a very large infertile ocean, poses special requirements, such as:
growing old: the eggs and larvae of nearly all marine organisms
spend some time (days to weeks) as plankton in the open water before settling
down (recruitment). Because of ocean currents, the small size of the islands
and the large ocean around, recruitment is uncertain and sporadic. Organisms
therefore must sustain many years of unsuccessful spawning.
living frugally: the concentration of nutrients in the water is
low, supporting only low densities of plankton and plant growth. In order
to survive through all seasons, marine organisms must be able to live thriftily.
The Kermadecs are not a place to find fast growing fish such as dense schools
of sardines, jack mackerels and other silver fish, and their predators.
Neither can one expect organisms needing good densities of phytoplankton,
such as mussels and scallops. The fish found here are mostly specialist
feeders, filling a small niche in this environment. But it is surprising
how many different species can be found in a single dive, and even more
awesome how many of these are found only here and nowhere else in the world.
To record them all, would require many dives. In this selection only the
most common are shown.
The following overview illustrates which fishes one can recognise when
diving the Kermadecs:
f031228: A young Abbott's moray eel (Gymnothorax eurostus)
peeps out from behind the shelter created by a shagpile coral. This coral
cloaks the rocky bottom while leaving a living space for others. Young
fish and eels enter through an opening like this, and keep it open, much
like antarctic seals keep their breathing holes open.
On right: f031227: Grey moray eel (Gymnothorax nubilus)
f031227: Grey moray eel (Gymnothorax nubilus) among shagpile
f031203: A Cook's scorpionfish (Scorpaena cookii)
is surprised by the photographer's light, looking much different than its
surroundings. But by day, in the presence of blue light, it looks very
much like the seaweeds around it.
This is what the Cook's scorpionfish looks like by day. For
this photo, the red and orange components of the light have been reduced,
simulating daylight at 10m depth.
f030916: Toadstool grouper (Trachypoma macracanthus)
and a mature Cook's scorpionfish (Scorpaena cookii) sitting side
by side. The toadstool grouper actively seeks prey whereas the scorpionfish
waits for prey to come near its mouth.
f031122: Toadstool grouper (Trachypoma macracanthus)
in its sleeping den. The fish is about to change colour, like pulling its
f030934: A young yellow banded perch (Acanthistius
cinctus) hovers in perfect balance inside its cave. One usually finds
several perches living together in the same cave. They form permanent bonds.
f031818: Goldribbon grouper (Aulacocephalus temmincki).
These groupers have a bright yellow line running on each side of their
backs. The rest of the body changes colour at will. Here it is just changing
from bright blue to black.
f031016: Northern kahawai (Arripis xylabion) in schooling
formation. This kahawai is endemic to the Kermadecs and must have adapted
to the paucity of pelagic food.
In this detail of previous image, it can be seen that the
black patterns on the back of the northern kahawai differs from that of
the coastal kahawai (Arripis trutta).(not shown)
f031023: These yellow and grey drummers are the same species
bigibbus), but different colour forms. Colour morphs are common in
plants, but much less common in animals. Feeding on mat forming algae,
they try to avoid being bitten by the numerous mimic blennies.
f031032: Caramel drummers (Girella fimbriata) and
grey drummers in stormy water with incessant and strong water movement.
Notice the large barnacle formations with matting red algae on the rocks.
This fish feeds on small algae, is very shy and endemic.
f031008: Grey knifefish (Bathystethus cultratus) swimming
near the surface. These fish are usually found in the most turbulent of
waters where suspended bubbles limit visibility. They feed on planktonic
organisms. In the background a school of northern kahawai.
An enlargement of a section of previous picture shows its
odd knife shape, which is perfect for catching organisms living under and
on the surface of the sea. This fish is related to the blue maomao (Scorpis
violaceus) found in New Zealand and here.
f031221: The splendid hawkfish (Cirrhitus splendens)
is conspicuous by night but well camouflaged by day. it lives in the shallows
and is well equipped to hold on firmly to whatever unevenness the rocks
may offer. It eats small crustaceans. Notice the brushes at the tips of
its dorsal spines, characteristic of hawkfish.
f031129: The painted moki (Cheilodactylus ephippium)
is rare in NZ but common at the Kermadecs and Norfolk Island. It is a very
beautiful fish with spectacular markings and colours, particularly on its
face and tail.
f031126: At dusk, before the dark of night, fishes of all
kind come together to the few caves to find shelter for the night. On left
a yellow banded perch. In the centre a notch-head marblefish (Aplodactylus
etheridgii) and in the rear a few blackspot goatfish (Parupeneus
spilurus) , with painted moki hovering above. Out of view above, five
lionfish clinging to the wall. Notice how the marblefish is much more
brown coloured than the NZ variety.
f030931: Kermadec scalyfin (Parma kermadecensis) or
grey angelfish, resembles the black angelfish in shape but not colour.
These fish are named scalyfins because their dorsal fin spines have scale
patterns in between, which sets them apart from other groups of fishes.
f032002: Lord Howe coralfish (Amphichaetodon howensis)
are usually found in pairs. The pair bond lasts for life. These fish are
well equipped to pick morsels of food like shrimps from the gaps in between
f031207: This Lord Howe coralfish has just bedded down for
the night and is in the process of changing it colours.
f031519: Striped boarfish (Evistias acutirostris)
f031510: striped boarfish are often found in small groups
in the shelter of caves like this. The roofs of such caves are often richly
covered in sessile animal life like gorgonians, zoanthids, featherstars
and so on. Notice the masked moki (Cheilodactylus sp.) in the bottom
f031526: A large fruit bowl coral offers a vast hiding place
underneath, happily accepted by these small damselfishes. They also sleep
here, which explains why they cannot be found during night dives. The green
ones with spots are young two-spot demoiselles (Chromis dispilus),
whereas the yellow ones are Easter Island demoiselles
They have beautiful colours and white masks (not clearly visible).
Detail of the bottom right corner.
f031311: In this photo one can see that two-spot demoiselles
are very common in some places at the Kermadecs. They prefer promontories
with nearby flowing water to catch their planktonic food.
f031313: Blue maomao (Scorpis violaceus) are also
common around promontories. Here a dense school of blue maomao and demoiselles
accompanies a diver, out of sheer curiosity. Among the blue maomao, often
blue knifefish are found, conspicuous by their golden backs (not shown).
f032008: A male orange wrasse (Pseudolabrus luculentus)
has changed his colour to bed down for the night. First he sees to it that
all his females have burrowed themselves in the coarse sand. Then he follows
f028614: This picture shows the male orange wrasse in daytime
colours, when it has its business suit on. Compare it with his pyjamas
f031235: Female morse-code leatherjacket (Thamnaconus
analis) found sleeping near a fruit bowl coral. Rather ill at ease,
it has erected its dorsal spine which prevents predators from swallowing
it. It derives its name from the dash-dot patterns on its sides, which
it can turn off at will, but the blue belly button remains.
f031803: Kingfish (Seriola lalandi). The kingfish
around the Kermadecs are few and far between, and they are slender, showing
signs of starvation.
Two Galapagos sharks (Carcharhinus galapagensis) patrolling
the sandy bottom near Fishing Rock. These sharks are quite inquisitive,
and come very near for a close look, which is rather frightening. They
have been known to attack people, but here they are rather small and docile.
They are typically 1.5m long, and very slender.
Frontal view of the Galapagos shark. The dark spot on its
dorsal fin is not typical, but identifies this individual. Galapagos sharks
are found over a large area in the southern Pacific Ocean. They resemble
small bronze whaler sharks.
Both Photos: Lance Kennedy.
In the grey volcanic sand in between submerged boulders off Fishing
Rock, lives a little fish which may remain undetected by the spying eyes
of the scientist. It is a little sand-diver, but no longer than 4cm,
much smaller than its relative in NZ. What makes this animal undetectable
is not only its sandy colour, but more so its phenomenal speed. For instance
it makes the journey from being burrowed in the sand, to a point above
it, 4-6 times its length, and back in less than 1/25th of a second! This
is too fast for the untrained eye, and it shows as two blurred images on
a camera running 'slow motion' at 50 frames per second.
They live here in their hundreds, and with some skill they can be herded
into a single confined spot of sand, no larger than two hands, temporarily
hiding four dozen of them. Fifty little fish, all staring at me, while
I was unable to see any of them. Regrettably, I have not been able to take
photographs due to rough conditions.