Growth and maturation of three commercially important coral reef species from American Samoa
2020
Pardee, Cassandra | Taylor, Brett M. | Felise, Sean | Ochavillo, Domingo | Cuetos-Bueno, Javier
This study presents age-based life history information on three small-bodied species targeted in the American Samoan fishery: Chlorurus japanensis palecheek parrotfish/fuga-alosama, Lethrinus rubrioperculatus spotcheek emperor/fiola pa`o`omumu, and Naso lituratus orangespine unicornfish/ili`ilia. Age and reproductive information were derived from sagittal otoliths and gonads. Maximum observed ages were 7 years for C. japanensis, 10 years for L. rubrioperculatus, and 25 years for N. lituratus. Due to a limited numbers of immature samples, a proxy for size at 50% maturity (L₅₀) was derived from the relationship between asymptotic fork length (L∞) and L₅₀ based on data published for species from similar geographic regions and respective families. L₅₀ was estimated at 20.9 cm for C. japanensis, 20.4 cm for L. rubrioperculatus, and 17.5 cm for N. lituratus. Derived estimates were within 1 % of the L₅₀ calculated for C. japanensis and N. lituratus from the limited number of immature samples collected in this study, indicating that for regions where sampling ability is limited, derived relationships between L∞ and L₅₀ can be used to calculate an appropriate proxy. Naso lituratus demonstrated a biphasic mortality schedule with a higher than expected total mortality rate in the first 7 years of life. The age-based demographic information presented here can be used for future stock assessments and ecosystem models, which should facilitate improved management.
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