Age and growth determination in Citharinus citharus (Geoffrey and St. Hilaire, 1809) in Onah Lake, Delta State, Nigeria

Abstract

An observation of the rings impressed on the polished sagittae otoliths of Citharinus citharus in the present study revealed reliable age data. Two daily rings were counted on the otoliths. These rings resulted from other factors including growth increments. Two types of rings (periodic and daily) were described. Two periodic rings were counted annually while the daily rings were impressed in multiples of two. A growth increment was also observed on scales. The widely spaced rings which resulted from rapid growth increments was observed in the juvenile scales while the reverse was the situation in the adult scales which as a result of slow growth had their rings more closely arranged. No annulus was observed on the scales. However, the pattern and distribution of the rings on both hard structures was used in age/growth estimation.

Keywords: Citharinus citharus, otolith, age, growth, tropics

Tropical Freshwater Biology Vol. 14 2005: 9-18