Analysis of precision in statolith derived age estimates of the tropical squid Photololigo (Cephalopoda : Loliginidae)

Precision in statolith derived age estimates among readers experienced in s tatolith age analysis was determined for both juvenile and adult individual s of the tropical loliginid squid Photololigo off Queensland, Australia. Ju venile age estimates were compared between two readers, while adult age est imates were compared among three readers. There was no reader effect in the age estimates of juveniles, but there was a trend of increasing age estima tes with consecutive replicate counts for each reader. In the case of adult squid there was a statistically significant difference in age readings amo ng readers, with the average greatest difference of 9.7 increments. However , this difference represented 5.6% of the lifespan of the oldest individual and 6.9% of the youngest aged adult. These differences were well within th e 10% requirement of replicate counts in previous studies. Furthermore the growth curves generated on age estimates from each reader did not differ si gnificantly. (C) 1999 International Council for the Exploration of the Sea.