VALIDITY OF USING TRANSLUCENT ZONES OF OTOLITHS TO AGE THE PILCHARD SARDINOPS-SAGAX NEOPILCHARDUS FROM ALBANY, WESTERN-AUSTRALIA

Otoliths (sagittae) of the pilchard (Sardinops sagar neopilchardus) fr om the Albany region of Western Australia were examined on a monthly b asis during 1989 to 1991. When read consecutively, with the month of c apture known, a clear annual cycle of an increase in marginal incremen ts to October followed by a decline was recorded. This pattern was, ho wever, severely distorted when samples were re-examined after having b een jumbled and the month of capture concealed. Younger age groups (le ss than or equal to 3) showed evidence of multiple rings being formed annually, but not in all years or individuals, and this was not eviden t in older individuals (greater than or equal to 4). Agreement between readings was low (43-53%), especially between different readers. Resu ltant growth curves showed that males grow to a smaller size (L(infini ty) = 164, K = 0.805, phi = 1.03) than females (L(infinity) = 174, K = 0.584, phi = 0.95). Agreement between counts of annuli and ages estim ated by using otolith weight and length was only 54% for all individua ls, but increased to 76% for individuals assigned the same age by diff erent readers. Given the poorer predictions of future catch rates from the relative number of 2-year-olds in the commercial catch using annu li (implying lower accuracy) and increased complexity in preparation, otolith weights will be the method adopted for future ageing.