Ciguatera in the Gilbert Islands — Cooper 
417 
port marine life. The whole population suffered 
severe protein deficiency, certainly due in large 
measure to the toxicity of the reef fish, which 
deprived the settlers of their natural source of 
animal protein. This general deficiency un- 
doubtedly contributed to the infant mortality 
referred to above. The population of Sydney 
Island was evacuated to the Solomon Islands in 
1958, the island having been found unsuitable 
for permanent settlement. 
EVOLUTION OF TOXICITY IN THE GILBERTS 
In the Gilbert Islands the evolution of toxicity 
of an island seems to follow a pattern. When 
toxicity first appears in an area only a few fish 
caught on a small patch of reef are found to be 
toxic. Within a few months many more fish 
become toxic, the toxicity is more severe, and 
the area where toxic fish are caught extends over 
some of the neighboring reefs. Within a short 
while (on Marakei about 2 years), nearly all 
species of reef-dwelling food fish and the roving 
carnivores that normally prey on them have be- 
come very poisonous. After some years have 
passed (on Marakei about 10), the toxicity be- 
gins to decrease. Small specimens of certain 
species become safe to eat; this improvement 
appears to start at the periphery of the toxic 
area and gradually works its way toward the cen- 
ter. The small fish of a species become safe to 
eat before the large ones of the same species, 
and the "safe” size becomes progressively larger; 
certain species become safe to eat before others. 
Eventually a stage is reached when all fish are 
being eaten, although sporadic cases of poison- 
ing may still occur; at this stage the Gilbertese 
do not admit to having a toxic area on their 
island. It is not known whether a reef, once 
"poisoned,” ever becomes completely free of all 
toxic fish, but from accounts collected in the 
Gilberts it seems highly unlikely. The reefs ap- 
pear to go into a "quiescent stage” when only 
an occasional large specimen of Lutianus bohar, 
Promicrops lanceolatus (specimens of 200-300 
lb are sometimes landed, but they are very un- 
common), or of Muraenidae may cause poison- 
ing. The toxicity may flare up again, when the 
cycle will be repeated, and it appears that, until 
a valid field test for toxicity has been discovered, 
any fish caught in a known toxic area should be 
regarded with suspicion. 
Unfortunately, due to the rapidity with which 
toxicity increases, it has not been possible to 
determine either the order in which species be- 
come toxic, or the first species to become toxic. 
However, at the height of toxicity most mem- 
bers of the following families or genera of fish 
are toxic: Acanthuridae, Balistidae, Caranx spp., 
Cirrhitidae, Holocentridae, Lethrinidae, Lutina- 
nidae, Mugilidae, Muraenidae, Scaridae, Serrani- 
dae, and Sphyraenidae; certain Mullidae may be 
toxic, and Labridae are also probably toxic, es- 
pecially the larger ones, but information on this 
family is lacking, as the Gilbertese do not like 
their taste and prefer not to eat them. 
As the toxicity declines, amongst the first fish 
that become safe to eat are the Holocentridae, 
Mugilidae, Cirrhitidae, Mullidae; the smaller 
species of grouper, Epinephelus menu, and al- 
lied species and Cepholopholis urodeius; small 
specimens of Lutianus kasmira and L. vaigiensis. 
On the other hand, some species remain ' toxic 
far longer than others, and among the ones that 
may remain toxic for many years are the follow- 
ing: A cant hums xanthopterus, Ctenochaetus 
spp., Lutianus bohar, L. semicinctus, L. mono- 
stigma, Lethrinus variegatus, Lpinephelus fusco- 
guttatus, Cephalopholis argus, C. mineatus, Vari- 
ola louti, Plectropomus truncatus, Promicrops 
lanceolatus, large Caranx spp., Scams spp., large 
Sphyraena spp., large Muraenidae. Monotaxis 
grandoculis and Gnathodentex aureolineatus 
may also remain toxic, but these fish are not at 
all common. More and more species become 
safe to eat, but C. mineatus and P. truncatus are 
particularly slow, and E. fuscoguttatus even 
slower to improve. Finally the reefs enter the 
quiescent stage with only a few species, Luti- 
anus bohar, Promicrops lanceolatus, and large 
Muraenidae, remaining potentially toxic. Large 
Sphyraena sp. have been found to remain very 
toxic in the vicinity of a toxic area, which in 
the Gilbert Islands may be almost anywhere in 
the colony. 
WINDS AND CURRENTS 
Throughout the Gilbert Islands the prevail- 
ing winds are the trade winds, blowing from 
the northeast, east, or southeast, with an occa- 
