Abstract

Scales, dorsal fin-rays and dorsal spines were explored as potential non-lethal ageing alternatives for juvenile goliath grouper; a protected species in U.S. waters. Annulus marks were validated for periodicity of annulus formation using marked-recaptured fish, oxytetracycline injections, and edge analysis. A 40% recapture rate provided a useful time series of in situ age and growth data. A subset of fish was sacrificed to compare scale, spine and ray ages to otolith ages. Spines showed the best relationship to corresponding otolith ages, even though annuli formed at different times of the year in spines versus otoliths. A biological age method corrected for this difference and agreement was improved. Scale and ray ages were unreliable. Dorsal spines are recommended as the primary method for ageing goliath grouper between the ages of 0 and 6 years. This study illustrates the use of a non-lethal method to determine age of a protected species.

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