Sex-biased dispersal and growth in sablefish (Anoplopoma fimbria) in the northeastern Pacific Ocean

Abstract

To examine the potential linkage between sex-biased growth and dispersal in demersal fish, we studied the movement distance and growth of tag-recaptured sablefish (Anoplopoma fimbria). Tagging was conducted by teams from Japan and the United States. From 1980 to 1984, 58,918 sablefish were captured by Japanese vessels and tagged with anchor tags, and between 1980 and 2007, 3319 sablefish were recaptured in the Bering Sea and northeastern Pacific. Of these 3319 fish, we analyzed data on 659 individuals for which we have reliable data on recapture location, sex and fork length at the time of release and recapture, and elapsed time longer than 10 days. Annual growth increments (mean±S.D.) were 2.5 ± 6.5 cm (males) and 3.5 ± 8.6 cm (females), and the movement distances (assumed to be straight) were 712 ± 800 km (males) and 877 ± 920 km (females). Females grew larger and moved longer distances than males. We calculated the growth increment deviation that accounted for the effects of elapsed time, curvilinear growth, and initial fork length at release using a von Bertalanffy growth model. The growth increment deviation increased significantly with the distance moved over elapsed time. In addition, the relationship between distance moved over elapsed time and the growth deviation differed significantly between sexes; females grew faster than males at a given movement distance. We suggest that female-biased dispersal is a factor generating female-biased growth in sablefish.