Differences in the Age of Pacific Hake (Merluccius productus) Using Whole Otoliths and Sections of Otoliths

Abstract

Ages determined for older Pacific hake from sections through the nucleus of otoliths were older than the ages determined from the otolith surface for the two populations studied. Growth of all parts of the otolith was not identical throughout the life of the fish. The change in the pattern of otolith growth occurred about the age at which the growth in length of the fish was reduced. Despite the disproportionate growth in length and height of the otolith, the thickness of the otolith, especially in the ventral interior portion, continued to increase with age. Section ages appear to be more reliable for older fish because of this allometric change in otolith growth with increasing fish age. It is suggested that the examination of sections of otoliths should become a routine approach in any attempt to age fish using otoliths. Key words: age determination, otolith, otolith section, otolith growth, aging errors, Pacific hake, Strait of Georgia