Use of An Age-Dependent Mark–Recapture Model in Fisheries Research

Abstract

An age-dependent generalization of the Jolly–Seber mark–recapture model for fish populations subject to birth, death, and migration is illustrated using data from a study on northern pike (Esox lucius) in Dorset, England. These data show strong evidence of differential survival with age. We estimate the average annual survival rate to be 50% for the pike aged 2 or more years and 34% for those of age 1 yr. We believe that this age-dependent mark–recapture model could be very useful for a wide range of fisheries research and management problems. Often in fisheries work the assumption that survival is independent of age has not been examined critically. We present guidelines helpful in designing mark–recapture studies. This includes a useful design which increases precision and also allows population size estimation to be robust to unequal catchability (heterogeneity or trap response) within an age-class.