A Method of Calculating Body Lengths from Otolith Measurements for Pacific Halibut and its Application to Portlock-Albatross Grounds Data between 1935 and 1957

Abstract

A change in growth rate of the halibut from the Portlock-Albatross grounds has occurred since the early 1930's. It is possible to measure this change in growth by studying the otoliths of fish taken by the commercial fishery in subsequent years. The calculation of body lengths from otolith measurements has provided a technique of reconstructing the growth patterns of each year-class. This method has been tested using the otoliths of recovered tagged halibut. The percentage deviations from average body length at each age demonstrate an increase in average length with time over the period 1920–1956. This increase is not exhibited among young fish of ages 1 through 4; it starts approximately with age 5 and continues throughout the older ages, where it is pronounced.