260 
PACIFIC SCIENCE, Vol. XV, April 1961 
TABLE 11 
Growth of Acanthurus triostegus sandvicensis Recovered After 1 Month or More 
Following Tagging 
(Period of tag retention includes both winter and fall or spring months, 1954-55) 
DATE 
RELEASED 
DATE OF 
RECOVERY 
STANDARD 
LENGTH 
MEASURED 
DEAD 
GROWTH 
(mm.) 
Tul. 6 
Dec. 14 
105 
X 
3.4 
23 
Mar. 25 
110 
3.5 
30 
Dec. 23 
115.5 
5.5 
Aug. 10 
Feb. 6 
113 
X 
7.8 
10 
Feb. 22 
110 
3.0 
13 
Jan. 28 
98 
X 
3.1 
27 
May 17 
97 
8.0 
Sep. 3 
Feb. 6 
101 
X 
7.2 
3 
Mar. 25 
102 
3.0 
21 
Jan. 24 
98.5 
4.0 
21 
Feb. 18 
123 
X 
7.0 
21 
Feb. 21 
105 
X 
7.4 
21 
Jul. 29 
101 
4.0 
28 
Dec. 23 
121 
X 
1.8 
28 
Jan. 21 
114 
2.0 
28 
Mar. 25 
122 
X 
1.8 
28 
Apr. 23 
124 
1.0 
Nov. 19 
Mar. 1 
105 
X 
3.8 
19 
Apr. 5 
152 
1.5 
23 
Mar. 19 
119 
0.5 
23 
Apr. 27 
105 
3.0 
23 
Jul. 6 
106.5 
7.5 
The next approach to obtaining the age of 
manini was the preparation of the length fre- 
quency curve of Figure 24. As the recruitment 
of the manini is seasonal, it seemed possible 
that year classes might stand out as modes on 
such a graph. At least for this curve, however, 
no definite modes are apparent. Probably the 
long period of recruitment (February to Octo- 
ber), coupled with individual variation in 
growth, precludes the formation of distinct 
modal groups in standard length. 
Age determinations of the manini would 
therefore seem possible only by rearing of fish, 
recovery of tagged fish (tagged at a size small 
enough to predict the age from growth rate with 
reasonable accuracy), or gross estimates from 
growth rate and knowledge of the maximum 
size. 
Although the age attained by the manini is 
unknown, the following information on the age 
of two surgeonfishes supplied by Spencer Tinker, 
director of the Waikiki Aquarium, indicates 
that at least some acanthurids are long-lived. 
Two unicorn fish ( Naso unicornis ) which were 
present in the aquarium when an employee ar- 
rived in 1935, lived until they succumbed as the 
result of an accident in 1955. In 1940 several 
specimens of Acanthurus xanthopterus approxi- 
mately 5-6 in. in length were placed in the 
aquarium. Two of these survived until 1951 in 
a small tank together; they had reached a size 
of about 20 in. At this time one slashed the 
_ 2 
e 0 . : Li * 
o 
o» # • • # • 
_ -2 
_£ . ... , — 
2 100 104 108 112 116 120 124 128 132 136 140 144 
Standard length (mmj 
Fig. 23= Growth of Acanthurus triostegus sandvi- 
censis on Oahu during the period Nov. 19, 1954, to 
Feb. 18, 1955, as based on the recovery of tagged fish 
which were in the water 1 month or more. The hori- 
zontal line was added at the zero point to facilitate 
comparison of the distribution of points with Figure 
22 . 
