Validation of annual growth increments in the otoliths of the lethrinidLethrinus mahsena and the lutjanid Aprion virescens from sites in thetropical Indian Ocean, with notes on the nature of growth increments inPristipomoides filamentosus

摘要

The lutjanids Pristipomoides filamentosus and Aprion virescens and the lethrinid Lethrinus mahsena are commercially important demersal bank and deep slope reef fish from the central Indian Ocean. To obtain von Bertalanffy growth parameter estimates for management purposes, length-based methods are commonly applied by the fisheries institutions of the region. Because the relatively long-lived, slow-growing nature of these species results in a lack of distinct modal progression in length-frequency data, such estimates are unreliable. In an attempt to obtain more reliable growth estimates, the feasibility of age-based methods (where age is determined from annual increments in otoliths) was investigated. Successful validation of annual or daily increments has been reported in two of these species (P. filamentosus and A. virescens), but not for the target areas of our study: the banks of the Seychelles and Mauritius.