Ac ant hums triostegus sandvicensis — Randall 
Fig. 4. Tide pool at low tide at Diamond Head, 
Oahu, from which the collections of Acanthurus trios- 
tegus sandvicensis of Figure 5 were made. 
the graph of Figure 5. The poison stations on 
August 13 and August 21 were interrupted by 
unexpected large waves, and no fish were col- 
lected. However, on these two dates manini were 
counted in the pool before rotenone was added 
and these numbers are indicated by the dotted 
233 
line on the graph. Probably there were at least 
twice as many small manini in the pool as are 
recorded, for most of the fish take cover rapidly 
when an observer approaches and are hidden 
before they can be counted. The sample of 36 
fish taken on September 12, on the other hand, 
may be higher relative to the overall number of 
tide-pool young at this time than it should be. 
Observation of other pools at Diamond Head 
and along the shore of the Ala Wai Yacht Basin 
prior to, during, and after September 12 failed 
to disclose any striking influx of young. Never- 
theless, the number of incoming young in Sep- 
tember is high and this month should be in- 
cluded with the period May to August as in- 
dicating large tide-pool recruitment on Oahu. 
Although this sampling from a single pool is 
not sufficiently great to be correlated closely with 
the similarly inadequate samples of adult gonads, 
the May to September recruitment seems to cor- 
respond roughly to the greater degree of gonad 
development from February to June. 
In more equatorial waters the A. triostegus 
triostegus appears to spawn throughout the year. 
The 221 adult fish used for the sex ratio deter- 
mination were collected mostly from the Mari- 
Feb. March April May June July Aug. Sept. Oct. 
Fig. 5. Weekly collections of Axanthurus triostegus sandvicensis made in 1953 from a single tide pool at 
Diamond Head, Oahu. Only specimens 30 mm. or less are recorded. Times of new moon are indicated by 
black circles. 
