VALIDATION OF AGE-DETERMINATION FROM OTOLITHS OF THE KING-GEORGE WHITING SILLAGINODES-PUNCTATA (PERCIFORMES)

The otoliths of the King George whiting Sillaginodes punctata were ass essed for their usefulness in adult-ageing, Whole, transverse-sectione d and broken/burnt sagittae displayed alternating opaque and transluce nt zones. Some small whole otoliths contained accessory areas of pigme nt, whilst large otoliths were too thick to transmit light, resulting in ambiguous counts in each case. Both marginal-increment analysis and treatment of fish with tetracycline demonstrated that the first three opaque zones formed annually, the first during the spring/summer of t he second year of life, and the second and third in each subsequent sp ring. Otolith thickness increased linearly with the completion of each new opaque/translucent zone. An ageing protocol based on whole otolit hs, supplemented with the breaking/burning of ambiguous otoliths is re commended. An algorithm for calculating age in months from otolith cou nts based on a fi?red birth-date of the mid-point of the spawning seas on is presented.