Craig et al.: Population biology and harvest of Acanthurus lineatus 
681 
as long as 44 years (Choat and Axe, 1996). In Sa- 
moa, A. lineatus occurs in high densities on coral reefs 
(0.4 fish/m 2 ; Craig, 1996). It maintains feeding terri- 
tories in shallow waters during the daytime but 
spends nights in deeper-water crevices where it is 
harvested by spear fishermen. 
The fisheries 
American Samoa has several small-scale fisheries for 
nearshore and offshore fishes and invertebrates 
(Craig et al., 1993). In 1994, the first year when all 
components of these fisheries were monitored, A. 
lineatus ranked second only to skipjack tuna 
(. Kate vonus pelamis) among all species harvested, 
accounting for 10% of the total catch of 295 metric 
tons (t) (DMWR 4 ). 
Acanthurus lineatus, a small fish averaging 18 cm 
fork length (FL) and 170 g, was caught in two inter- 
related coral reef fisheries: artisanal and subsistence 
harvests. Multispecies landings in these two fisher- 
ies were 76 and 86 t, respectively, in 1994 (Saucer- 
man 3 ). The artisanal fishery consisted of 56 night- 
time spear divers, among whom 15 fished regularly 
(about 15 days per month) by free diving and scuba 
diving. At 28 t, A. lineatus accounted for 39% by 
weight of artisanal catches (Fig. 1). The subsistence 
fishery was more diverse: fish were captured by gill 
nets, throw nets, rod-and-reels, handlines, and by spear 
fishing; invertebrates were captured by hand picking 
and spearing. Many species were taken; A. lineatus 
4 DMWR (Dep. Marine and Wildlife Resources), PO Box 3730, 
Pago Pago, American Samoa 96799. Unpubl. data. 
Figure 1 
Catch composition (by weight) of fish families in the 1994 
artisanal fishery in American Samoa. Redrawn from 
Saucerman (see Footnote 3 in the text). 
accounted for only 1-3% of subsistence catches. In both 
artisanal and subsistence fisheries, use of destructive 
fishing practices (dynamite, poison) was infrequent. 
Materials and methods 
Tutuila Island in American Samoa (14°S, 171°W) is 
a steep volcanic island ( 142 km 2 ) with 55 km of fring- 
ing coral reef. It has two seasons, a wet summer (Oct- 
May) and a slightly drier and cooler season (Jun- 
Sep) characterized by 2.5°C cooler nearshore water 
temperatures and increased SE trade winds. 
Nearshore water temperature (taken seaward of the 
reef flat at 0.3 m depth) ranged from 27°C to 31°C 
(n= 295 daily measurements). Additional details 
about physical variables are presented below as they 
relate to changes in fish condition. Rainfall and wind 
data were obtained from NOAA. 5 
Data were collected from 1) field studies conducted 
by snorkeling in shallow waters (1-4 m) on the coral 
reefs fronting the villages of Afao, Leone, and Matu’u 
(Fig. 2) and from 2) market samples of the artisanal 
fishery. Reef flats at the study sites were narrow 
(100-250 m), dropped abruptly to a depth of 3-6 m, 
and descended gradually thereafter to 20 m. The 
outer reef flat inhabited by A. lineatus consisted of 
consolidated limestone, encrusting coralline algae, 
5 NOAA (National Oceanic and Atmospheric Administration). 
1994. Local climatological data, annual summary with com- 
parative data, Pago Pago, American Samoa. National Climatic 
Data Center, Asheville, North Carolina, ISSN 0198-4357, 8 p. 
Tutuila Island, showing locations of study sites at the villages of 
Afao, Leone, and Matu’u. The main study reef at Afao (see en- 
largement at right) shows the spawning site of A. lineatus in the 
outer reef channel (x), the nighttime rest region (R) for A. lineatus 
using the study area, and the reef flat edge (dashed line). 
