Age estimation and maturity of the ridge-scaled macrourid (Macrourus whitsoni) from the Ross Sea

Juveniles of the macrourid rattail Macrourus whitsoni were collected by the NIWA research vessel Tangaroa during the BioRoss survey of the Western Ross Sea and Balleny Islands, with the purpose of analyzing the otoliths to generate more accurate age estimates for this species. Intensive analysis of otoliths from small specimens greatly increased confidence in the interpretation of the zone structure displayed in the early growth rings. The findings supported the interpretation protocols used in previous work on this species. Von Bertalanffy growth curves were generated and compared to previous results finding no significant differences between the years. Von Bertalanffy parameters for the pooled dataset with unsexed juveniles are L? 76.12, K 0.065 and t0 -0.159 for males and L? 92.03, K 0.055 and t0 0.159 for females. Revised estimates of the mean total length–at– maturity (38.8cm, 46.4cm) and mean age–at–maturity (10.6 years, 13.6 years) are presented for males and females respectively, using a reduced probit model.