Age and growth analysis of the mosshead sculpin Clinocottus globiceps Girard 1857 (Pisces: Cottidae) from Helby Island, British Columbia

Abstract

The age and growth of the cottid fish Clinocottus globiceps Girard from tidepools at Helby Island, British Columbia, Canada were investigated with the aid of whole saccular otoliths (sagittae); ages were validated by marginal increment analysis. Four hundred and twenty five specimens were examined from 214 females and 211 males. Marginal increment analysis on specimens with one to three opaque zones suggested an annual ring deposition in sagittae during the late autumn and spring months. The C. globiceps population was composed of individuals from less than 1 year to 5 years of age for fish measuring between 5–120 mm standard length. Growth was faster for younger than for older age groups. Lengths-at-age data were fitted to the Gompertz growth model, and estimates of the model parameters L0, G and g were 26.7 mm 1.58 and 0.30 for pooled cohorts, respectively. The highest levels of growth occurred during late spring and early summer, when water temperatures were at maximum and food was most abundant. The lowest levels of growth occurred during the autumn and winter months.