232 
PACIFIC SCIENCE, Vol. XV, April 1961 
TABLE 5 
Gonad Length as a Percentage of Standard Length by Month, 1952-53 
MONTH 
NO. OF 
FEMALES 
GONAD LENGTH 
x 100 
1 
NO. OF 
MALES 
GONAD LENGTH 
\/ 1 nn 
STANDARD LENGTH 
X ioU 
STANDARD LENGTH 
Range 
Mean 
Range 
Mean 
Oct. 
15 
7.1-18.2 
9.4 
14 
5.6-22.8 
9.4 
Nov. 
2 
7.7-14.4 
11.1 
12 
8.3-22.8 
15.5 
Dec. 
4 
12.3-25.0 
14.3 
11 
10.0-22.1 
15.9 
Jan. 
9 
8.6-25.6 
13.5 
10 
8.4-25.0 
17.9 
Feb. 
15 
14.1-25.6 
18.2 
31 
20.4-34.5 
28.6 
Mar. 
19 
13.5-32.2 
19.3 
25 
12.8-35.7 
28.6 
Apr. 
17 
10.4-26.4 
17.3 
7 
22.8-38.5 
29.4 
May 
6 
9.8-23.3 
16.2 
5 
18.2-31.2 
25.6 
Jun. 
9 
7.0-34.5 
13.5 
5 
15.0-25.1 
20.0 
Jul. 
10 
7.5-17.6 
9.6 
9 
8.1-26.3 
14.9 
Aug. 
9 
5.5-11.9 
7.2 
8 
6.5-23.8 
13.2 
Sept. 
22 
5.0-14.5 
8.4 
19 
7.6-17.3 
9.0 
variation in the time when this occurs in indi- 
vidual fish, hence the ultimate small size is not 
apparent when the values of a number of fish 
are averaged by month. The ovary of a 145 mm. 
female taken on August 7, for example, was only 
8 mm. in length. 
The gonad measurement data are more sig- 
nificant in indicating a definite spawning season 
of the manini when coupled with the results of 
sampling the young throughout the year. Trans- 
forming and small juvenile specimens were ab- 
sent from inshore areas during the fall and early 
winter months of 1952-53. Extensive observa- 
tion and collecting were undertaken during the 
winter and early fall to ascertain the time of the 
first and last arrivals of acronuri from the pelagic 
realm. The first transforming young were sighted 
on February 14; the last of the season straggled 
in on October 6. In 1954 the first young were 
discovered on February 9. During my absence 
from the state, my wife and Philip Helfrich 
made an effort to determine the date of the last 
influx of young in 1954. In October only a single 
small juvenile was collected; it was taken on 
the 9th of the month and measures 27.5 mm. 
in standard length. It is completely transformed; 
therefore it had been in the tide-pool zone for 
about 5-8 days (see sections on transformation 
and growth). The first transforming young of 
the 1955 season were observed on January 27. 
The time between the finding of the first ripe 
female of the season and the first incoming 
young and the time between the last ripe female 
and the last incoming young constitute estimates 
of the duration of larval life. The last ripe female 
of the 1952—53 season detected in the sampling 
program (see Table 6) was found on July 21. 
The first ripe female of the 1953-54 season was 
found on December 1. The last ripe females of 
this season were observed in the July 16 sample. 
The three estimates of the duration of larval 
life from the above data are 71, 78, and 83 days. 
Admittedly such estimates are subject to consid- 
erable error. Their average, 77 days, approxi- 
mates 2 l /z months. 
In order to obtain quantitative data on the 
recruitment of young to inshore areas of Oahu, 
a single large tide pool at Diamond Head ( Fig. 
4) was chosen for repeated collections of ma- 
nini. This pool is nearly isolated at low tide. 
An overhanging ledge on the left (east) side 
of the pool provides excellent cover for the small 
fish. Pools as large as this but lacking such cover 
contain fewer manini. Each week at low tide 
the narrow outlet to the sea was occluded with 
a net, and all the manini in the pool were poi- 
soned with rotenone. A total of 157 manini less 
than 30 mm. in standard length were taken from 
the pool during the season (Fig. 5). Nineteen 
specimens 30 mm. or longer were collected; 
these are presumed to have been in the tide- 
pool zone for more than one week (see section 
on growth) and hence are probably migrants 
from adjacent pools. They are not included in 
