Validation of otolith daily increments in the tropical eel Anguilla marmorata

Abstract

To determine the periodicity of the deposition of growth increments in the otolith of the glass eels of the tropical eel Anguilla marmorata, an otolith validation experiment was performed. Glass eels were captured at the mouth of the Poigar River, north Sulawesi Island, Indonesia, and then immersed in an alizarin complexone (ALC) solution to mark their otoliths. After being held under natural conditions in the river for 20 d, it was found that the number of rings outside the ALC mark was 20.1 0.7 (mean SD), which coincided with the number of days after the ALC treatment. This validation experiment indicated that the growth increments in the otoliths of A. marmorata glass eels were deposited daily and can be used for daily age determination.