The age of hoki was determined by counting bands in otolith cross‐sections. The technique was validated using the progression of length modes in length‐frequency distributions (for age classes 0+ to 4+) and the progression of strong and weak year classes in age‐frequency distributions from commercial catches sampled off the west coast of the South Island, New Zealand, from 1988 to 1994. Von Bertalanffy growth parameters for the west coast and Cook Strait spawning populations are significantly different, providing further support for a two‐stock hypothesis. In both areas female hoki have a growth rate significantly faster than males, and also a greater life expectancy.