Population biology and harvest of a coral reef surgeonfish (Acanthurus lineatus) in American Samoa

Craig, Peter; Choat, H; Axe, L; Saucerman, S

The herbivorous bluebanded surgeonfish, Acanthurus lineatus, was a major species harvested on coral reefs in American Samoa, accounting for 39% by weight of artisanal catches in 1994. Spanning occurred year-round but peaked during the austral spring and summer (October-February). A dense pulse of recruits settled onto the outer reef flat in March-April. Apparent survival was low during the first year but increased thereafter (80% year). The fish were strongly site-attached on a daily basis, but an estimate 60% of the adults switched territories at least once during a 3-year period, thereby negating attempts to estimate morality through attrition rates of marked individuals. Estimates of fish condition changed through the year, generally paralleling seasonal changes in a suite of environmental factors. The fish grew rapidly, attaining 70-80% of their total growth during their first year, followed by slow growth and long life (up to 18 years), characteristics that confounded standard growth analyses by producing age-specific growth parameters. Growth was best described by a two-phase von Bertalanffy growth curve for ages 0-3 and ages 4-1, with the separation based on the age at which 50% of this population reached maturity. Indicators of fishing pressure over a 9-year period were equivocal but did not point to significant overfishing.

Population biology and harvest of a coral reef surgeonfish (Acanthurus lineatus) in American Samoa

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