Determining the most efficient method of age determination for estimating the age structure of a fish population

Less precise, but economic methods for estimating the age of individual fish can provide better estimates of age structure than precise, but expensive methods. The benefits of using a precise ageing method can be compromised by its cost, which may restrict the size of the sample aged. If sample size is restricted, the effect of sampling error on an age structure may be greater than the effect of ageing error from a less precise ageing method that does not restrict sample size. We used Monte Carlo simulations to assess the relative size of sampling and ageing errors when estimating the age structure of populations of Pomacentrus moluccensis from the southern Great Barrier Reef, Australia. Sampling error associated with ageing less than 200 individuals was, on average, larger than the effects of most commonly reported ageing errors. Other factors that may complicate this comparison of ageing methods involve the financial cost of different methods and the logistics of sampling more fish.